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BACKGROUND OF THE INVENTION This invention relates generally to the field of working metal by lathe turning. More particularly, the invention encompasses a method for cutting extremely small grooves in hard tool steel. The requirement to cut small grooves in a turning blank of hard tool steel may arise in a variety of applications. One such application is in the manufacture of heat exchanger tubing. Either one or both of the surfaces of such tubing is frequently configured with, for example, a pattern of ribs or fins in order to provide an enhancement in heat transfer performance over tubing having smooth surfaces. One such type of an enhancement is a pattern of longitudinal ribs on the internal surface of the tubing. This type of enhancement readily adapts itself to use in a manufacturing process in which flat metal strip is roll formed into a cylindrical shape with the resultant longitudinal seam being welded to form the tubing. A surface enhancement embossing step can be added to the roll forming and welding process so that the pattern of longitudinal ribs can be formed on the flat strip before it is roll formed and welded into a finished tube. Modern equipment and techniques enable the manufacture of quantities of tubing at extremely high speeds by this process. To form the ribs, the metal strip is pressed between two rollers. At least one of the rollers has a pattern of grooves that is the mirror image of the rib pattern to be embossed into the strip. Under the pressure exerted by the two rollers, strip metal, usually copper, flows into the grooves to form the ribs of the enhancement pattern. The width of the metal strip needed to form tubing of the size commonly used in refrigerant-to-air heat exchangers in air conditioning and refrigeration systems is about 3 cm. On a strip this width will be embossed a surface enhancement comprising somewhere in the range of 70 to 80 ribs, each rib having a height on the order of 0.25 mm. The ribs are thus relatively very small. It follows that the size of the grooves in the embossing roller is correspondingly very small. To withstand wear, the embossing rollers must be made of a very hard material such as a tool steel. When in operation, there are not only compression forces acting on the grooved embossing wheel but also shear forces acting on the metal between adjacent grooves on the roller. For this reason, the metal of the roller must also be very tough and the configuration of the grooves must be such as to reduce the incidence of localized concentrations of stress in the metal between the grooves of the roller. There should be a high degree of uniformity in the planforms of the individual grooves in the grooved embossing roller. Forming grooves of the desired size and shape in a metal hard enough and tough enough to be suitable for an embossing roller presents unique challenges. One method of forming grooves is by grinding them in to the roller with a suitable abrasive wheel. This is a time consuming and therefore expensive task. One reason for the time required is that the abrasive wheel must be relatively frequently dressed up. Otherwise, the uniformity of the grooves is degraded because of abrasive wheel wear. In addition, one is not able to achieve certain specific groove configurations because of limitations in the grinding art. What is needed is a method of forming very small grooves in a very hard and very tough tool steel blank. The method should be capable of forming grooves of a variety of cross sections and not be excessively time consuming. SUMMARY OF THE INVENTION The present invention is a method of forming very narrow, on the order of the width of a human hair, grooves in a hard tool steel blank by lathe turning. Before the development of this method, it was generally believed among those skilled in the art that it was not possible to turn grooves of that size in hard steels without breaking the very small cutting tool necessary. The method combines advances in machine turning and cutting tool technologies as well as metallurgy with simple but extremely painstaking accuracy to enable the lathe cutting of grooves in the blank. The method allows formation of grooves comparatively rapidly and therefore leads to an overall reduction in the cost of a finished embossing wheel. As will be disclosed in the below detailed description, the method includes the use of a turning blank comprised of a very hard steel alloy. The lathe used is of the precision or ultraprecision type. In this type of machine it is possible, to accuracies on the order of a few microns (μm) or less, to very precisely position and rotate the turning blank as well as to very precisely control the position of the cutting tool with respect to the turning blank. The cutting tool has a very hard and tough cubic boron nitride (CBN) tip that is prepared to precisely the desired configuration of the groove to be turned into the blank. The turning blank is positioned in the lathe and dressed to minimize or eliminate, to accuracies only possible using a precision or ultraprecision lathe, runout. The cutting tool, also to accuracies only possible on a precision or ultraprecision lathe, is positioned, with respect to the surface of the blank to be grooved, so that side loads on the tool will be at a minimum during cutting operations. The rotational speed of the lathe is precisely controlled so that the linear speed of the work past the cutting tool is within a predetermined optimum range of values. And the feed rate of the cutting tool into the work is precisely controlled so that it is within a predetermined optimum range of values. BRIEF DESCRIPTION OF THE DRAWINGS The accompanying drawings form a part of the specification. Throughout the drawings, like reference numbers identify like elements. FIG. 1 is an isometric view of an embossing roller having a grooved region produced by the method of the present invention. FIG. 2 is an isometric view of a rolling station where longitudinal ribs are roll embossed into a metal strip. FIG. 3 is a diagram of a typical groove from to be cut in to an embossing wheel by the method of the present invention. FIG. 4 is a diagram of a groove form cut in to an embossing wheel by a prior art method. FIG. 5 is a top plan view of a cutting tool used in the method of the present invention. FIG. 6 is a side elevation view of a cutting tool used in the method of the present invention. FIG. 7 is a detailed plan view of the tip of the cutting tool depicted in FIG. 5. FIG. 8 is a side elevation view of a portion of a lathe. FIG. 9 is a top view of a portion of a lathe. FIG. 10 is a flow diagram of the method of the present invention. DESCRIPTION OF THE PREFERRED EMBODIMENT FIGS. 1, 2 and 3 illustrate one application for the method of the present invention. FIG. i depicts embossing roller 10. Centrally located on circumferential surface 11 of roller 10 is working zone 12. FIG. 2 shows embossing roller 10 installed and operating at a roll embossing station in a heat exchanger tube manufacturing line. Working zone 12 comprises a number of parallel circumferential grooves 13 as depicted in cross section in FIG. 3. Copper strip 30 from a strip supply (not shown) passes between embossing wheel 10 and backing roller 20. Rollers 10 and 20 have a tangential distance between them that is less than the thickness of strip 30, so that metal in the strip is forced into grooves 13 in working zone 12 as the strip passes between the rollers. This produces a pattern of longitudinal ribs in enhancement region 31 on strip 30. Further steps in the tube manufacturing process (not shown) include roll forming the strip into a tubular configuration and welding the seam formed between the two joined edges of the strip. In one example of a strip roll embossed in the manner described above, there are over 70 ribs in the approximately three centimeter wide enhancement region. Each groove 13 is therefore very narrow and the grooves are very closely spaced. Walls 14 between adjacent grooves are therefore also very narrow. Strip rolling operations impose very high lateral stresses in the metal of walls 14. The possibility of stress cracking in the groove walls is reduced if radius R of the base of the groove is as large as other desired dimensions of the groove will permit. The prior art method of forming very small grooves in a metal turning blank, i.e. by abrasive grinding, is not capable of forming grooves having completely rounded groove bottoms. FIG. 4 depicts the cross section of grooves 12' formed by grinding and shows that the bottom of the groove is flattened with smaller radii R' of curvature on each side of the groove bottom. Because of these smaller radii, the areas at the edges of the base of the groove serve as stress raisers and increase in the possibility of failure by cracking in walls 14'. The prior art grinding method is also not capable of producing a sharply defined shoulder but rather only a chamfered or rounded shoulder 15' at the top of the groove. Furthermore, the grinding wheel used in grinding the grooves is subject to loss of its shape due to wear. As the wheel wears, the shape of the grooves it cuts changes unless the operator dresses up the wheel frequently. The practice of the method of the invention requires the use of the precision or ultraprecision lathes that are now available. A precision lathe is capable of accuracies in setting up the work and positioning a cutting tool to accuracies of on the order of five to ten microns and a spindle runout accuracy on the order of less than one micron. An ultraprecision lathe has the capability of similar accuracies on the order of less than one half micron and less than a tenth of a micron. An ordinary metal tool making lathe, by comparison, has a runout accuracy of five to eight microns respectively. Runouts in this latter range can cause changes in cutting forces sufficient to cause failure of the cutting tool. Only with the higher precision lathes can spindle runout be sufficiently minimized and the cutting tool be positioned with respect to the work with sufficient accuracy to allow the practice of the invention. There are a number of lathes available that have sufficient precision to turn grooves according to the teaching of the present invention. Precision and ultraprecision lathes have the same basic features as conventional lathes and differ from such conventional lathes primarily in the accuracy with which they are able to control the various lathe functions. FIGS. 8 and 9, in partial semi-schematic side elevation and top views, show a grove being cut in circumferential surface 11 of roller 10 by cutting tool 40. Roller 10 is mounted on chuck 72 of lathe 70. Chuck 72 is rotated by a drive (not shown) in headstock 71. Cutting tool 40 is mounted in tool holder 75, which is in turn mounted on crossfeed 74. Crossfeed 74 is mounted on carriage 73. The position and movement of cutting tool 40 with respect to roller 10 are determined by the positions and movements of carriage 73 and crossfeed 74. These positions and movements, in a precision or ultraprecision lathe, are controlled by a computer (not shown). The work must be precisely positioned on the lathe spindle, then the circumferential surface (12 in FIG. 1) dressed by turning to ensure that the axis of the work is precisely coincident with the axis of rotation of the spindle and that all points on the circumferential surface are equidistant from those axes. The cutting tool used in the practice of the invention should have a very hard cutting tip. A good choice for the application is a tool having a cubic boron nitride (CBN) tip. FIGS. 5 and 6 respectively show a top and side elevation view of a suitable tool. FIG. 7 shows a detailed view of a portion, denoted by VII in FIG. 5, of the tip of the tool. Tool 40 is prepared from an ISO (International Organization for Standardization) tool VNMA 16048 having a 35° angle (angle β in FIG. 7). Base 45 of tool 40 is comprised of a cemented carbide material. Cutting region 41 is comprised of a layer of CBN material 42 affixed to base 45 by a layer of cemented carbide material 43 and a layer of silver brazing material 44. Tip 46 is prepared by a suitable process such as grinding to produce a configuration appropriate to the groove to be turned (Cf. groove 13 in FIG. 3). The dimensions of tip 46 can be very small. One cutting tool successfully used to cut grooves on an embossing wheel has a tip radius (R in FIG. 7) of about 40 microns, an included angle (α) of 15° and a cutting depth (D) of about 300 microns. It is important that, in manufacturing the cutting tool, the tool be precisely symmetrical about axis A. Any asymmetry present can cause side forces during turning that can lead to fracture of the cutting tip. The properties of the CBN cutting tip must be selected for optimum performance based on the composition of the steel into which the grooves will be turned. A suitable steel for use as an embossing wheel is AISI (American Iron and Steel Institute) D2 tool steel. D2 is a high carbon, high chromium steel having a Rockwell C hardness in the range of 50 to 60. The extremely hard carbide particles in D2 steel are, relatively, very large (on the order of 25 to 500 microns). Some carbide particles thus are larger than the diameter of the tip of the cutting tool. During turning, the force on the tool is very high when it is passing through a carbide particle. The force on the tool is much lower when the tool is passing through the non-carbide matrix of the steel. The variation in cutting forces on the tool subjects it to the possibility of fatigue failure. On steels of this type, the CBN cutting material must have high fracture toughness, at the expense of hardness and wear resistance. On the other hand, turning when a steel having a relatively fine grained carbide content presents a different problem. An example of this type of steel is CPM® (Crucible Particle Metallurgy) 9V, which has carbide particles of less than 25 microns and a Rockwell C hardness in the range of 53 to 58. When such a steel is turned, the total force required to cut the steel is greater than for a steel such as D2 but the variation in force on the tool as it is cutting is much less. Resistance to fatigue failure is therefore not so significant a consideration but the tool used for cutting in this case should be harder and more wear resistance. A suitable CBN material for cutting grooves in steels such as D2 is General Electric® B6500. A suitable CBN material for use with CPM® 9V is DeBeers DBC50. Critical to the ability to cut grooves of such small dimensions into hard tool steels is the alignment of the cutting tool with respect to the work. The axis (A in FIG. 7) of the tool must be positioned precisely perpendicularly to circumferential surface 12 as the tool is advanced into the work. If the tool axis is not perpendicular to the work during turning, side forces will be present that can easily cause the tool tip to fracture. Finally, the cutting speed and cutting tool feed rate must be held within limits for success in practicing the method of the invention. Cutting speed, the linear speed of any point on cylindrical surface 12, must be between 80 and 200 meters per minute and preferably about 160 meters per minute. If the speed is less than this range, the wear rate on the cutting tool is excessively high. If the speed exceeds this range, the cutting operation overheats the steel of the work piece, damaging the structure of the steel and altering its strength and other properties. The cutting tool feed rate must be within the range ten to 20 microns per revolution and preferably about 20 microns per revolution. Feed rates less than this range approach the lower limit of the capability of the cutting tool control apparatus and precise control of feed rate is difficult or impossible, leading to sticking or slipping of the tool positioner and an irregular feed of the tool into the work, leading to the possibility of fracture of the tool. Feed rates greater than this range impose loads on the tool that may lead to fracture. FIG. 10 is a flow diagram showing he steps necessary to practice the method of the present invention. In steps 101 and 102, the workpiece is prepared by mounting it on the lathe chuck and predressing it by turning to remove runout. In steps 201 and 202, a cutting tool having physical properties appropriate to the composition of the workpiece is selected and the tip of the tool is prepared by forming it to the shape necessary to cut the desired groove. In step 301, the cutting tool is aligned so that the longitudinal axis of the tool is precisely perpendicular to the surface into which the groove will be cut. In step 302, the lathe rotational speed is set to the proper speed. Finally, in step 303, the cutting tool is advanced into the workpiece at the proper feed rate to cut the groove. If more than one groove is to be cut into the workpiece, the cutting tool would be moved to the new location and steps 301 through 303 repeated for each groove cut. The method of the invention offers significant time, and therefore cost, advantages over prior art methods of forming small grooves in a work piece. For example, to lathe turn the grooves in an embossing roller as described in this disclosure, requires about 15 minutes. To accomplish the same task by a grinding method can require up to eight to 10 hours. Further, the grinding process may not be capable of forming grooves of the desired configuration.

4y

TECHNICAL FIELD [0001] The present invention relates to structure of a damper that can notify a user of occurrence of a prescribed event by a tactile signal in an operation unit that receives a user's manual operation at an operating part. BACKGROUND ART [0002] Patent Literature 1 describes an accelerator pedal unit that uses hysteresis characteristics of a damper having a pair of cams so that excessive pressing of the accelerator pedal is impeded by applying a suitable load against pressing of the accelerator pedal and a strain on a foot of a driver is reduced when the accelerator pedal is held at an almost-constant position. [0003] In this accelerator pedal unit, rotation of an accelerator pedal arm is transmitted to a rotating shaft of the damper through a transmission mechanism including a link member and the like so that rotations of the accelerator pedal arm in both directions are damped. In detail, one end of the link member is fixed to the rotating shaft of the damper so that rotation of the link member causes rotation of the rotating shaft of the damper. On the other hand, an engaging member is fixed to the accelerator pedal arm at its opposite end across a rotating shaft of the accelerator pedal arm from the accelerator pedal. This engaging member is slidably held by the link member. Accordingly, when the accelerator pedal arm rotates, the rotating shaft of the damper is rotated through the link member in the direction depending on the rotation direction of the accelerator pedal. Owing to the hysteresis characteristics of the damper, an appropriate load is given at the time of pressing the accelerator pedal while the load is reduced at the time of return of the accelerator pedal (Paragraphs 0071-0084 and FIGS. 13-19, for example). CITATION LIST Patent Literature [0000] Patent Literature 1: Japanese Unexamined Patent Application Laid-Open No. 2002-12052 SUMMARY OF INVENTION Technical Problem [0005] Excessive pressing of an accelerator pedal increases the energy expenditure rate of an automobile, and is undesirable from the viewpoint of traveling energy cost reduction or the like. Thus, in order to pursue so-called eco-driving, it is necessary for a driver to adjust the degree of pressing of an accelerator pedal while constantly grasping the traveling conditions of his automobile according to visual information obtained from, for example, an eco-meter in the instrument panel when the automobile is moving. [0006] However, the convenience of a driver is improved if the driver can grasp more intuitively a signal of prompting energy saving driving without confirming display on an instrument panel. This does not apply only to an automobile, and it is convenient if a user who manually operates an operating part can intuitively grasp a signal that notifies the user of occurrence of a prescribed event. [0007] The present invention has been made considering the above situation. An object of the invention is to provide an operation unit that receives user's manual operation at an operating part and can give an intuitively perceivable signal conveying notice of occurrence of a prescribed event, and a damper suitable for use in the operation unit. Solution to Problem [0008] To solve the above problems, according to the present invention, a pivot pin, which rotates in conjunction with an operating part for receiving a user's manual operation, is connected with a damper for damping rotation of the pivot pin, and force of the damper to damp rotation of the pivot pin increases rapidly at a time when the pivot pin is rotated to a prescribed rotation angle. [0009] For example, the present invention provides a damper for damping rotation of a rotating shaft, comprising: [0010] a pair of cam members each having an inclined cam face inclined with respect to a rotation direction of the rotating shaft, upon a torque of the rotating shaft being transmitted to the cam members, the cam members rotating relative to each other about an axis of the rotating shaft and moving relative to each other in an axial direction of the rotating shaft; [0011] a housing part housing the pair of cam members and having an inner side surface on which the pair of the cam members moving and rotating relative to each other slide; and [0012] a friction resistance changing means changing a friction resistance impeding relative rotation of the pair of cam members stepwise by changing, in a stepwise manner, force of pressing the pair of cam members against an end portion of the housing part with increase of a relative rotation angle of the pair of cam members while pressing the pair of the cam members in the axial direction of the rotating shaft against the housing part at the end portion located in the axial direction of the rotating shaft so as to allow the pair of cam members to press against each other at the inclined cam faces. [0013] Here, the friction resistance changing means may comprise: [0014] an elastic body being placed within the housing part so as to be compressed in the axial direction of the rotating shaft by increase of an amount of a relative movement of the pair of cam members in the axial direction, biasing the pair of cam members in the axial direction of the rotating shaft; and [0015] at least two inclined areas being formed in the inclined cam face of at least one of the pair of cam members, being inclined at different angles from each other with respect to the direction of the relative rotation of the pair of cam members, and being arranged in the direction of the relative rotation of the pair of cam members. [0016] Or the friction resistance changing means may comprise an elastic means placed within the housing part so as to be compressed in the axial direction of the rotating shaft by increase of a relative moving amount of the pair of cam members in the axial direction, the elastic means biasing the pair of cam members in the axial direction of the rotating shaft by restoring force; and [0017] an elastic coefficient of the elastic means may increase stepwise with increase of a compression amount of the elastic means. [0018] Further, the present invention provides an operation unit for receiving a manual operation at an operating part from a user, wherein; [0019] the operation unit comprises; [0020] an arm having the operating part; [0021] a pivot pin, the arm being fixed to the pivot pin so that the operating part is located at a position away from an axis; [0022] a bracket holding the pivot pin rotatably about the axis of the pivot pin by force to be given to the operating part by the manual operation; and [0023] a damper damping rotation of the pivot pin; and [0024] the damper comprises; [0025] a pair of cam members each having an inclined cam face inclined with respect to a rotation direction of the pivot pin, upon a torque of the pivot pin being transmitted to the cam members, the cam members rotating relative to each other about the axis of the pivot pin and moving relative to each other in an axial direction of the pivot pin with the inclined cam faces in sliding contact with each other; [0026] a housing part being fixed to the bracket and housing the pair of cam members, housing part having an inner side surface, the pair of the cam members sliding on the inner side surface while moving and rotating relative to each other; [0027] a friction resistance changing means changing a friction resistance impeding relative rotation of the pair of cam members stepwise by changing, in a stepwise manner, force of pressing the pair of cam members against an end portion of the housing part with increase of an angle of relative rotation of the pair of cam members while pressing the pair of the cam members in the axial direction of the pivot pin against the housing part at the end portion located in the axial direction of the pivot pin so as to allow the pair of cam members to press against each other at the inclined cam faces. [0028] Here, the friction resistance changing means may comprise: [0029] an elastic body being placed within the housing part so as to be compressed in the axial direction of the pivot pin by increase of a relative moving amount of the pair of cam members in the axial direction, biasing the pair of cam members in the axial direction of the pivot pin; and [0030] at least two inclined areas being formed in the inclined cam faces of at least one of the pair of cam members, being inclined at different angles from each other with respect to a direction of the relative rotation of the pair of cam members, and being arranged in the direction of the relative rotation of the pair of cam members. [0031] Further, the friction resistance changing means may comprise an elastic means being placed within the housing part so as to be compressed in the axial direction of the pivot pin by increase of a relative moving amount of the pair of cam members in the axial direction and biasing the pair of cam members in the axial direction of the pivot pin by restoring force so as to allow the inclined cam faces of the pair of cam members to press against each other; and [0032] an elastic coefficient of the elastic means may increase stepwise with increase of a compression amount of the elastic means. Advantageous Effects of Invention [0033] According to the present invention, a damper connected to a pivot pin rotating in conjunction with an operating part for receiving user's manual operation increases force of damping rotation of the pivot pin at a time when the pivot pin rotates to a prescribed rotation angle. Accordingly, the user can detect a change in feeling of operation of the operating part by tactile sensation. Thus, for example, in an application case where the operation unit is an accelerator pedal unit having an accelerator pedal as an operating part, it is possible to increase a load on a foot with which a driver presses the accelerator pedal at a time when the accelerator pedal is pressed to a position where the energy expenditure rate of an automobile increases to a prescribed level. By this, while driving the automobile, the driver can detect a change in operational feeling of the accelerator pedal as a signal for energy-saving driving of the automobile. Thus, while driving the automobile, the driver can intuitively perceive the signal for energy-saving driving of the automobile through pressing operation of the accelerator pedal. BRIEF DESCRIPTION OF DRAWINGS [0034] FIG. 1 is a view illustrating schematic configuration of a holding portion of an accelerator pedal arm 2 in an accelerator pedal unit 1 according to a first embodiment of the present invention; [0035] FIGS. 2(A) and 2(B) are an external view and a right side view of a pedal pivot pin 4 , and FIG. 2(C) a view illustrating conceptually a state of the pedal pivot pin 4 fitted in a pedal bracket 5 ; [0036] FIG. 3 is an exploded view of a damper 6 according to the first embodiment of the present invention; [0037] FIGS. 4(A) and 4(B) are left and right side views of the damper 6 in an initial state (with an accelerator pedal 21 being non-pressed), and FIG. 4(C) an A-A cross-section of FIG. 4(A) ; [0038] FIGS. 5(A) and 5(B) are left and right side views of a case 64 , and FIG. 5(C) a B-B cross-section of FIG. 5(A) ; [0039] FIGS. 6(A) and 6(B) are a front view and a back view of a cover 65 , and FIG. 6(C) a C-C cross-section of FIG. 6(A) ; [0040] FIGS. 7(A) , 7 (B) and 7 (C) are a front view and left and right side views of a rotating cam 61 , FIG. 7(D) a D-D cross-section of FIG. 7(C) , and FIG. 7(E) a view illustrating schematically a profile shape of a cam face 612 on a pitch circle 615 centering at an axis O; [0041] FIGS. 8(A) , 8 (B) and 8 (C) are a front view, a back view and a side view of a slide cam 62 , FIG. 8(D) an E-E cross-section of FIG. 8(A) , and FIG. 8(E) a view illustrating schematically a profile shape of a cam face 622 on a pitch circle 625 centering at the axis O; [0042] FIGS. 9(A) , 9 (B) and 9 (C) are views for explaining two-stage damping motion of the damper 6 associated with pressing the accelerator pedal 21 ; [0043] FIG. 10 is an exploded view of a damper 16 according to a second embodiment of the present invention; [0044] FIGS. 11(A) and 11(B) are left and right side views of the damper 16 in an initial state (with an accelerator pedal 21 being non-pressed), and FIG. 11(C) an A-A cross-section of FIG. 11(A) ; [0045] FIG. 12(A) is a view for explaining structure of a combination spring 163 , FIG. 12(B) a view illustrating a state of the combination spring 163 before increase of the spring constant, and FIG. 12(C) a view illustrating a state of the combination spring 163 having the increased spring constant; [0046] FIGS. 13(A) and 13(B) are left and right side views of a case 164 , and FIG. 13(C) a B-B cross-section of FIG. 13(A) ; [0047] FIGS. 14(A) , 14 (B) and 14 (C) are a front view and left and right side views of a rotating cam 161 , FIG. 14(D) a D-D cross-section of FIG. 14(C) , and FIG. 14(E) a view illustrating schematically a profile shape of a cam face 1612 on a pitch circle 615 centering at an axis O; [0048] FIGS. 15(A) , 15 (B) and 15 (C) are a front view, a back view and a side view of a slide cam 162 , FIG. 15(D) an E-E cross-section of FIG. 15(A) , and FIG. 15(E) a view illustrating schematically a profile shape of a cam face 622 on a pitch circle 625 centering at the axis O; [0049] FIG. 16 is a view for explaining two-stage damper motion of the damper 16 associated with pressing the accelerator pedal 21 ; [0050] FIG. 17 is a view for explaining two-stage damper motion of the damper 16 associated with pressing the accelerator pedal 21 ; and [0051] FIG. 18 is a view for explaining two-stage damper motion of the damper 16 associated with pressing the accelerator pedal 21 . DESCRIPTION OF EMBODIMENTS [0052] In the following, embodiments of the present invention will be described referring to the drawings. First Embodiment [0053] First, structure of an accelerator pedal unit 1 according to the present embodiment and structure of a damper 6 used in the accelerator pedal unit 1 will be described. [0054] FIG. 1 is a view illustrating schematic configuration of a holding portion of an accelerator pedal arm 2 in the accelerator pedal unit 1 according to the present embodiment. [0055] As illustrated, the accelerator pedal unit 1 of the present embodiment comprises: an accelerator pedal arm 2 , at one end portion of which an accelerator pedal 21 as an operating part for receiving driver's operation is fixed; a pedal pivot pin 4 , to which the accelerator pedal arm 2 is fixed so that the accelerator pedal 21 is located at a prescribed distance L3 from an axis O; a pedal bracket 5 , which holds the pedal pivot pin 4 rotatably in both directions α and β about the axis O so that the accelerator pedal arm 2 swings by operation (i.e. pressing and releasing) of the accelerator pedal 21 , and is fixed to a body (not shown) of an automobile; a retaining ring 7 for preventing dropping-off of the pedal pivot pin 4 from the pedal bracket 5 ; a spring 3 , whose both end portions are connected to the accelerator pedal arm 2 and the pedal bracket 5 so that the spring 3 is compressed with the press down of the accelerator pedal 21 , and which makes the accelerator pedal arm 2 (which has been rotated about the axis O of the pedal pivot pin 4 by pressing the accelerator pedal 21 ) return to an initial position by the elastic force of the spring 3 when the accelerator pedal 21 is released; and a detection part (not shown), which includes a potentiometer and the like for detecting an angle of rotation θ about the axis O of the pedal pivot pin 4 and outputting the detected angle to the outside. [0056] Further, the accelerator pedal unit 1 further comprises: a damper 6 in which resisting force for damping rotation of the pedal pivot pin 4 increases stepwise according to the angle θ of the rotation of the pedal pivot pin 4 , in order that a suitable load is applied on a foot with which driver presses down the accelerator pedal 21 , but the load on the driver's foot becomes rapidly heavier by at least tactually-detectable magnitude at the time when the accelerator pedal 21 is pressed to a position where the energy expenditure rate of the automobile deteriorates to a prescribed level (or at the time when the pedal pivot pin 4 rotates to a prescribed angle θ1 in the prescribed direction α about the axis O of the pedal pivot pin 4 ); and bolts 8 and nuts 9 for fixing the damper 6 to the pedal bracket 5 . [0057] In the following, these component parts 2 - 9 will be described. However, detailed description will be omitted with respect to parts similar to those in an ordinary accelerator pedal unit, such as the accelerator pedal arm 2 , the spring 3 , the retaining ring 7 , the detection part, and the like. In the following, the direction α in which the pedal pivot pin 4 rotates about its axis O at the time of pressing the accelerator pedal 21 is called the normal rotation direction α, and the direction β in which the pedal pivot pin 4 rotates about its axis O at the time of releasing the accelerator pedal 21 is called the reverse rotation direction β. [0058] FIGS. 2(A) and 2(B) are an external view and a right side view of the pedal pivot pin 4 , and FIG. 2(C) a view illustrating conceptually a state of the pedal pivot pin 4 fitted in the pedal bracket 5 . [0059] As illustrated, the pedal pivot pin 4 is a stepped pin with integrally and concentrically formed three cylindrical shaft sections 41 - 43 having respective outer diameters different from one another. In detail, the pedal pivot pin 4 comprises a support section 41 , a damper connecting section 42 having a larger diameter than that of the support section 41 , and a pedal arm fixing section 43 having a larger diameter than that of the damper connecting section 42 , successively from the side of the other end face 412 . [0060] On the outer periphery 431 of the pedal arm fixing section 43 , is fixed the accelerator pedal arm 2 arranged in the direction crossing the axis O of the pedal pivot pin 4 . Accordingly, interlocking with swinging of the accelerator pedal arm 2 , the pedal pivot pin 4 rotates in both directions α and β about the axis O of the pedal pivot pin 4 . [0061] The damper connecting section 42 is formed integrally with an end face 432 of the pedal arm fixing section 43 , and the outer circumference 421 of the damper connecting section 42 is, along the direction of the axis O, cut off to have two flat surfaces at width-across-flat t1 which is nearly equal to as the outer diameter R2 of the support section 41 , extending from a step surface (an end face of the damper connecting section 42 ) 422 produced by an outer diameter difference between that section 42 and the support section 41 to a position that does not reach a step surface (the end face of the pedal arm fixing section 43 ) 432 produced by an outer diameter difference between that section 42 and the pedal arm fixing section 43 . That is to say, on the side of the pedal arm fixing section 43 of the outer circumference 421 of the damper connecting section 42 , is formed a support area 425 having cylindrical surface to be supported by one side plate 52 of the below-described two side plates 52 and 53 of the pedal bracket 5 ; and on the side of the support section 41 from this support area 425 , are formed the two flat surfaces 423 opposed to each other with width-across-flat t1 nearly same as the outer diameter R2 of the support section 41 . [0062] The support section 41 is formed integrally with the end face 422 of the damper connecting section 42 . In the outer circumference 411 of the support section 41 , is formed a groove 413 in the circumferential direction for fitting the retaining ring 7 at a least distance L2 (See FIG. 1 ) between the two side plates 52 and 53 of the pedal bracket 5 from the step surface (the end face of the pedal arm fixing section 43 ) 432 formed by the outer diameter difference between the pedal arm fixing section 43 and the damper connecting section 42 . [0063] The pedal pivot pin 4 having the above-described shape is inserted, first the side of the support section 41 , through a pin insertion hole 521 of the one side plate 52 of the pedal bracket 5 , through the damper 6 fixed to the other side plate 53 of the pedal bracket 5 , and through a pin insertion hole 531 of the other side plate 53 of the pedal bracket 5 , and rotatably supported by the two side plates 52 and 53 of the pedal bracket 5 at two positions, i.e. at the support area 425 of the damper connecting section 42 and at the support section 41 . In this state, the two flat surfaces 423 of the damper connecting section 42 are contained in the damper 6 fixed to the other side plate 53 of the pedal bracket 5 . Inside the damper 6 , the two flat surfaces 423 of the damper connecting section 42 face respective flat surfaces 618 of the inner wall of the below-described rotating cam 61 . Accordingly, when the pedal pivot pin 4 rotates about its axis O associated with swinging of the accelerator pedal arm 2 , the flat surfaces 423 of the damper connecting section 42 immediately make the rotating cam 61 rotate due to contact with the respective opposed flat surfaces 618 of the inner wall of the rotating cam 61 . Thus, as soon as the accelerator pedal 21 is pressed down, the damper 6 starts damping of rotation of the pedal pivot pin 4 , to apply a suitable load on the foot of the driver who presses the accelerator pedal 21 . [0064] As illustrated in FIG. 1 , the pedal bracket 5 integrally comprises: a bottom plate 51 , which is fixed to an automobile body; and the two side plates 52 and 53 , which support the pedal pivot pin 4 rotatably in both directions α and β. Although not shown, the pedal bracket 5 further comprises a stopper, which comes in contact with the other end portion (the end portion opposite to the accelerator pedal 21 with respect to the pedal pivot pin 4 ) of the rotating accelerator pedal arm 2 in the normal rotation direction α of the pedal pivot pin 4 at a prescribed position. Contact between this stopper and the other end portion of the accelerator pedal arm 2 prevents the pedal pivot pin 4 from rotating more than a prescribed angle θ 2 (See FIG. 9 ) in the normal rotation direction α. [0065] In the bottom plate 51 , are formed through-holes 511 at a plurality of positions corresponding to threaded holes in the automobile body. By screwing bolts inserted through these through-holes into the threaded holes in the automobile body, the pedal bracket 5 is fixed to the automobile body at a prescribed mounting position. [0066] A pin support hole 521 , whose diameter is smaller than that of the pedal arm fixing section 43 of the pedal pivot pin 4 and larger than that of the damper connecting section 42 , is formed in the one side plate 52 of the two side plates 52 and 53 . The other side plate 53 is placed across the one side plate 52 from the accelerator pedal arm 2 so as to face the one side plate 52 at a distance L2 greater than the case length (the distance L1 between both end faces 6410 A and 6410 B of a case body 641 ) of the damper 6 . Further, in the other side plate 53 , are formed the pin support hole 531 and bolt insertion holes (not shown) positioned on both sides of the pin support hole 531 . Here, the pin support hole 531 is concentric with the pin support hole 521 of the one side plate 52 and has a larger diameter than that of the support section 41 of the pedal pivot pin 4 . [0067] The damper 6 is placed between the two side plates 52 and 53 , and fixed to the other side plate 53 by tightening of nuts 9 and the bolts 8 inserted through bolt insertion holes 6421 in flange portions 642 of the case 64 and the bolt insertion holes in the other side plate 53 . In this state, the pedal pivot pin 4 is inserted, first the side of the support section 41 , through the pin support hole 521 of the one side plate 52 until the groove 413 of the support section 41 comes out of the pin support hole 531 of the other side plate 53 . As a result, as described above, the pedal pivot pin 4 is rotatably supported in the pin support holes 521 and 531 of the two side plates 52 and 53 at the two positions, i.e. at the support area 425 of the damper connecting section 42 and at the support section 41 , in a state that the two flat surfaces 423 of the damper connecting section 42 are contained in the damper 6 fixed to the other side plate 53 . Then, the retaining ring 7 having an outer diameter larger than the pin support hole 531 of the other side plate 53 is fitted in the groove 413 of the support section 41 , to prevent dropping-off of the pedal pivot pin 4 out of the pedal bracket 5 . [0068] FIG. 3 is an exploded view of the acceleration pedal unit 1 according to the present embodiment. Further, FIGS. 4(A) and 4(B) are left and right side views of the damper 6 in an initial state (a state in which the accelerator pedal 21 is not pressed), and FIG. 4(C) an A-A cross-section of FIG. 4(A) . [0069] As illustrated in the figures, the damper 6 comprises: a pair of cams (the rotating cam 61 and a slide cam 62 ), whose rotation relative to each other about the axis O causes their inclined cam faces 611 and 621 to slide on and in contact with each other; a coil spring 63 , which biases the slide cam 62 in the direction of pressing the each inclined cam face 621 of the slide cam 62 against the corresponding inclined cam face 611 of the rotating cam 61 ; the case 64 , which houses these component parts 61 - 63 and is fixed to the other side plate 53 of the pedal bracket 5 ; and a disk-shaped cover 65 , which seals the case 64 . [0070] Inside the case 64 sealed by the cover 65 , the rotating cam 61 and the slide cam 62 are fitted in each other so that their inclined cam faces 611 and 621 engage with each other in accordance with the rotation relative between the rotating cam 61 and the slide cam 62 about the common axis O. The coil spring 63 is placed between a bottom face 62711 of a spring guide hole 6271 formed in the slide cam 62 and a bottom face 6415 of the case 64 so that the cam face 622 of the slide cam 62 are pressed against the cam face 612 of the rotating cam 61 . In the initial state of the damper 6 , the coil spring 63 has been preloaded, and owing to biasing by this coil spring 63 , each inclined cam faces 621 of the slide cam 62 is located at a prescribed position (initial position) relative to the corresponding inclined cam face 611 of the rotating cam 61 . Although details will be described later, each inclined cam face 611 of the rotating cam 61 includes two successive areas having different inclination angles with respect to a pitch circle 615 centering at the axis O (i.e. a first inclined area 611 A and a second inclined area 611 B having a larger inclination angle than that of the first inclined area 611 A, mentioned in order from the side of the initial position of the inclined cam face 621 of the slide cam 62 ) (See FIG. 7(E) ). [0071] In the above-described structure, when the rotating cam 61 is rotated in the normal rotation direction α relative to the slide cam 62 while constraining rotational movement of the slide cam 62 relative to the case 64 , then the slide cam 62 moves in the direction of getting away from the rotating cam 61 along a cam guide portion 613 of the rotating cam 61 while the inclined cam faces 621 slide on the corresponding inclined cam faces 611 of the rotating cam 61 . [0072] Here, until the rotating cam 61 rotates to the prescribed angle θ1 in the normal rotation direction α relative to the slide cam 62 , each inclined cam face 621 of the slide cam 62 slides on the first inclined area 611 A while only an edge portion 621 A of the inclined cam face 621 is in contact with the first inclined area 611 A in the inclined cam face 611 of the rotating cam 61 . During this, the distance between the bottom face of the slide cam 62 and the bottom face 6415 of the case 64 becomes gradually smaller, and therefore the coil spring 63 is further compressed. As a result, the coil spring 63 presses more strongly the inclined cam faces 621 of the slide cam 62 against the first inclined areas 611 A in the inclined cam faces 611 of the rotating cam 61 , and presses more strongly the bottom face 617 of the rotating cam 61 against the cover 65 (the below-mentioned seating face 657 ; See FIG. 6 ). Accordingly, with increase of the angle of rotation of the rotating cam 61 in the normal rotation direction α relative to the slide cam 62 , friction resistance, for example, between the inclined cam faces 621 of the slide cam 62 and the inclined cam faces 611 of the rotating cam 61 and between the bottom face 617 of the rotating cam 61 and the seating face 657 of the cover 65 increases gradually, and the torque of the rotating cam 61 in the rotation direction about the axis O increases gradually. [0073] When the rotating cam 61 is further rotated in the normal rotation direction α relative to the slide cam 62 , the whole area of each inclined cam face 621 of the slide cam 62 comes in contact with the second inclined area 611 B (which is steeper than the first inclined area 611 A with respect to the rotation direction of the pedal pivot pin 4 and the rotating cam 61 ) at the time when the rotating cam 61 rotates to the prescribed angle θ1 in the normal rotation direction α, and the inclined cam face 621 slides on the second inclined area 611 A. As a result, at the time when the rotating cam 61 rotates to the prescribed angle θ1 in the normal rotation direction α, the slide cam 62 exerts greater force in the direction of resisting rotation of the rotating cam 61 in comparison with the case where the inclined cam face 621 slides on the first inclined area 611 A of the gentle slope, and therefore the torque of the rotating cam 61 in the rotation direction about the axis O increases rapidly. The coil spring 63 is further compressed, and the inclined cam faces 621 of the slide cam 62 are pressed more strongly against the second inclined areas 611 B in the inclined cam faces 611 of the rotating cam 61 , and the bottom face 617 of the rotating cam 61 is pressed more strongly against the seating face 657 of the cover 65 . Accordingly, with increase of the angle of rotation of the rotating cam 61 in the direction α relative to the slide cam 62 , the friction resistance, for example, between the inclined cam faces 621 of the slide cam 62 and the inclined cam faces 611 of the rotating cam 61 and between the bottom face 617 of the rotating cam 61 and the seating face 657 of the cover 65 increases gradually, and the torque of the rotating cam 61 in the rotation direction about the axis O increases gradually. [0074] During this, when the rotation of the rotating cam 61 is once stopped at any point in time, the inclined cam faces 621 of the slide cam 62 come to rest on the inclined cam faces 611 of the rotating cam 61 . At that time, friction resistance is produced in the direction of resisting the tendency of the coil spring 63 toward elongation, and the torque of the rotating cam 61 in the rotation direction about the axis O decreases rapidly. [0075] Further, when the rotating cam 61 is rotated in the reverse rotation direction B, the slide cam 62 moves in the direction of getting close to the rotating cam 61 along the cam guide portion 613 of the rotating cam 61 while the inclined cam faces 621 slide on the inclined cam faces 611 of the rotating cam 61 . As a result, the distance between the bottom face of the slide cam 62 and the bottom face 6415 of the case 64 becomes gradually greater. And thus the coil spring 63 gradually returns (elongates) to the initial preload state, and the friction resistance, for example, between the inclined cam faces 621 of the slide cam 62 and the inclined cam faces 611 of the rotating cam 61 decreases gradually. Accordingly, with decrease of the rotation angle of the rotating cam 61 in the normal rotation direction α, the torque of the rotating cam 61 in the rotation direction about the axis O decreases gradually. [0076] The above-described damper 6 has hysteresis characteristics suitable to use as a hysteresis generation mechanism (hys-unit) that applies a suitable load at the time of pressing the accelerator pedal 21 and reduces load while the accelerator pedal 21 is held at a certain position. When the damper 6 is assembled in the accelerator pedal unit 1 , the damper 6 can not only realize natural accelerator pedal operation feeling while generating natural acceleration force, but also generate a rapid change in operational feeling of pressing the accelerator pedal 21 , which can be detected as a signal for energy-saving driving of an automobile, at the time when the accelerator pedal 21 is pressed excessively. Each of the component parts 61 - 65 of the damper 6 realizing such functions will be described. [0077] FIGS. 5(A) and 5(B) are left and right side views of the case 64 , and FIG. 5(C) a B-B cross-section. [0078] As illustrated, the case 64 integrally comprises: a case body 641 of a bottomed cylindrical shape; and the two flange portions 642 projecting in radial directions from the outer periphery 6412 of the case body 641 . [0079] The cover 65 is fitted in an opening 6414 of the case body 641 . In the inner periphery of the opening 6414 , is formed a threaded portion 6416 into which a threaded portion 652 of the outer periphery 651 of the cover 65 is screwed. By tightening of this threaded portion 6416 and the threaded portion 652 in the outer periphery 651 of the cover 65 , the cover 65 is fitted in the opening 6414 of the case body 641 while preloading the coil spring 63 housed in the case body 641 . In an edge portion of the case body 641 , a plurality of recessed portions 6411 for welding, which are used for fixing the cover 65 fitted in the opening 6414 , are formed at almost regular angular intervals about the axis O of the case body 641 . [0080] In the central area of the bottom face 6415 of the case body 641 , are formed a through-hole 6413 through which the axis O of the case body 641 passes, and a ring-shaped spring guide portion 6417 surrounding the outer circumference of the through-hole 6413 . The spring guide portion 6417 is set into the coil spring 63 inserted in the case body 641 , and fixes the position of one end 631 of the coil spring 63 . [0081] Further, in the inner periphery 6418 of the case body 641 , are formed three grooves 6419 along the direction of the axis O of the case body 641 at almost regular angular intervals about the axis O of the case body 641 . One end of each groove 6419 passes through the end face 6410 A of the case body 641 on the opening side. When the slide cam 62 is inserted through the opening 6414 of the case body 641 , projecting portions 623 on the outer periphery 624 of the slide cam 62 are slidably inserted into these grooves 6419 . By this, rotational movement of the slide cam 62 relative to the case 64 is constrained. In other words, rotational movement of the slide cam 62 relative to the pedal bracket 5 is constrained. [0082] Although, in the present embodiment, the three grooves 6419 are formed in the inner periphery 6418 of the case body 641 at almost regular angular interval about the axis O, the number and layout of the grooves 6419 are determined in accordance with the number and layout of the projecting portions 623 of the slide cam 62 that is used. [0083] On the other hand, the two flange portions 642 are formed integrally with the outer periphery 6412 of the case body 641 so as to project outward from both sides of the opening-side end face 6410 A of the case body 641 . In these flange portions 642 , are formed the bolt insertion holes 6421 for inserting the bolts 8 at positions that correspond to the respective bolt insertion holes in the other side plate 53 of the pedal bracket 5 when a through-hole 653 formed in the central area of the cover 65 fitted in the opening 6414 of the case body 641 is aligned with the pin insertion hole 531 of the other side plate 53 of the pedal bracket 5 . [0084] FIGS. 6(A) and 6(B) are a front view and a back view of the cover 65 , and FIG. 6(C) a C-C cross-section of FIG. 6(A) . [0085] As illustrated, in the outer periphery 651 of the cover 65 , is formed the threaded portion 652 that is screwed into the threaded portion 6416 formed in the opening 6414 of the case body 641 . In one surface (the surface to be faced toward the outside of the case body 641 ) 654 of the cover 65 , is formed a hexagon socket 656 for inserting a tool for rotating the cover 65 relative to the case body 641 . On the other surface (the rear surface to be faced toward the inside of the case body 641 ) 655 of the cover 65 , is formed a seating face 657 on which the bottom face 617 of the rotating cam 61 moves frictionally in the course of rotation. By rotating the tool inserted in the hexagon socket 656 in the surface 654 of the cover 65 , the threaded portion 652 formed in the outer periphery 651 of the cover 65 is screwed in the threaded portion 6416 formed in the opening 6414 of the case body 641 , and thereby the bottom face 617 of the rotating cam 61 is pressed by the seating face 657 of the cover 65 . As a result, the rotating cam 61 and the slide cam 62 are pressed into initial positions within the case body 641 , and the coil spring 63 is preloaded between the bottom face 6415 of the case body 641 and the bottom face 62711 (See FIG. 8(D) ) of the spring guide hole 6271 . [0086] Further, in the central area of the cover 65 , is formed the through-hole 653 having the inner diameter R2 larger than the outer diameter R1 of the damper connecting section 42 of the pedal pivot pin 4 . In an assembled state of the damper 6 , the axis O of the case body 641 passes through the through-hole 653 , the inside of the rotating cam 61 , and the through-hole 6413 of the bottom face 6415 of the case body 641 (See FIG. 4(C) ). The pedal pivot pin 4 is inserted, first the side of the support section 41 , into the through-hole 653 , and passes through the inside of the rotating cam 61 , so as to protrude from the through-hole 6413 of the bottom face 6415 of the case body 641 . [0087] FIGS. 7(A) , 7 (B) and 7 (C) are a front view and left and right side views of the rotating cam 61 , FIG. 7(D) a D-D cross-section of FIG. 7(C) , and FIG. 7(E) a view illustrating schematically a profile shape of the cam face 612 on the pitch circle 615 centering at the axis O. [0088] As illustrated, the rotating cam 61 has a stepped cylindrical shape including the cam guide portion 613 as a small-diameter portion and a cam portion 610 as a large-diameter portion that are integrally formed. The cam guide portion 613 is an inner-diameter guide for the slide cam 62 and inserted into the inside of the slide cam 62 . On the other hand, the cam portion 610 has the cam face 612 on which the inclined cam faces 621 of the slide cam 62 slide. [0089] Into the inside of the rotating cam 61 , the pedal pivot pin 4 is inserted from one end face 616 toward the other end face (bottom face 617 ) after passing through the through-hole 653 of the cover 65 . In an inner wall 614 of the rotating cam 61 , are formed two flat surfaces 618 facing each other at a width-across-flat T1 corresponding to the width-across-flat t1 of the damper connecting section 42 of the pedal pivot pin 4 . When the damper connecting section 42 of the pedal pivot pin 4 is inserted into the inside of the rotating cam 61 , these flat surfaces 618 come in contact with the corresponding flat surfaces 423 of the damper connecting section 42 of the pedal pivot pin 4 , so that the torque of the pedal pivot pin 4 is transmitted to the rotating cam 61 . As a result, associated with rotation of the pedal pivot pin 4 in both directions α and β caused by operation of the accelerator pedal 21 , the rotating cam 61 also rotates in both directions α and β about the axis O while generating friction resistance, for example, between the inclined cam faces 611 formed in the cam face 612 and the inclined cam faces 621 of the slide cam 62 . [0090] On the pitch circle 615 centering at the axis O, the cam face 612 (the face on the side of the cam guide portion 613 ) of the cam portion 610 periodically repeats concave forms and convex forms in the direction of the axis O. In detail, in the cam face 612 of the cam portion 610 , three inclined cam faces 611 inclined to the circumferential direction of the pitch circle 615 (the rotation direction of the pedal pivot pin 4 and the like) are formed at almost regular angular intervals about the axis O. Further, between each pair of adjacent inclined cam faces 611 , is formed a step face 619 for determining the initial position of an inclined cam face 621 of the slide cam 62 . [0091] In each inclined cam face 611 , the two inclined areas 611 A and 611 B, whose inclination angles with respect to the circumferential direction of the pitch circle 615 (i.e. inclination angles with respect to the rotation direction of the pedal pivot pin 4 and the like) are different from each other, are formed successively in the direction of the rotation of the pedal pivot pin 4 and the like. In detail, each inclined cam face 611 includes the first inclined area 611 A inclined at a prescribed angle A1 with respect to the circumferential direction of the pitch circle 615 and the second inclined area 611 B inclined at an angle A2 larger than the inclination angle A1 of the first inclined area 611 A with respect to the circumferential direction of the pitch circle 615 , being arranged in this order from the side of the corresponding step face 619 in the normal rotation direction α of the rotating cam 61 . Accordingly, when the rotating cam 61 rotates in the normal rotation direction α interlocking with the pedal pivot pin 4 , each inclined face 621 of the slide cam 62 starts rotational movement relative to the cam face 612 of the rotating cam 61 . First, the inclined cam face 621 goes sliding on the first inclined area 611 A of the gentle slope from the initial position determined by the corresponding step face 619 toward the second inclined area 611 B. Thereafter, at the time when the rotating cam 61 rotates to the prescribed angle θ1 in the normal rotation direction α, the inclined cam face 621 comes on the second inclined area 611 B that is steeper than the first inclined area 611 A, and slides on this second inclined area 611 B. [0092] FIGS. 8(A) , 8 (B) and 8 (C) are a front view, a back view and a side view of the slide cam 62 , FIG. 8(D) an E-E cross-section of FIG. 8(A) , and FIG. 8(E) a view illustrating schematically a profile shape of the cam face 622 on the pitch circle 625 centering at the axis O. [0093] The slide cam 62 comprises: a cylindrical cam portion 620 , into which the cam guide portion 613 of the rotating cam 61 is slidably inserted; and projecting portions 623 formed on the outer periphery 624 of the cam portion 620 along the axis O of the cam portion 620 . [0094] In the inner periphery of the cam portion 620 , is formed a stepped hole 627 having a spring guide hole 6271 as a large-diameter portion on the side of a bottom face 626 of the cam guide portion 620 . This spring guide hole 6271 is used for receiving the one end 631 of the coil spring 63 . [0095] The cam face (the end face opposite to the bottom face 626 ) 622 of the cam portion 620 periodically repeats concave forms and convex forms in the direction of the axis O on the pitch circle 625 centering at the axis O. In detail, in the cam face 622 of the cam portion 620 , three inclined cam faces 621 inclined at nearly the same angle A2 as that of the second inclined areas 611 B of the rotating cam 61 to the circumferential direction of the pitch circle 625 (the rotation direction of the pedal pivot pin 4 and the like) are formed at almost regular angular intervals about the axis O. Further, for each inclined cam face 621 , are formed a flat face 628 , which follows the inclined cam face 621 , and an inclined face 629 that comes in contact with a step face 619 in the cam face 612 of the rotating cam 61 . [0096] When the cam guide portion 613 of the rotating cam 61 is inserted into the inside of the cam portion 620 in a state that the cam face 622 of the cam portion 620 is faced toward the cam face 612 of the rotating cam 61 , the cam guide portion 613 of the rotating cam 61 protrudes from the side of the bottom face 626 of the cam portion 620 . The cam guide portion 613 protruding from the side of the bottom face 626 of the cam portion 620 is inserted into the coil spring 63 , and the spring guide hole 6271 of the cam portion 620 is made to enclose the one end 631 of the coil spring 63 . The coil spring 63 , the slide cam 62 and the rotating cam 61 , which are assembled in the above way, are housed, first the side of the other end 632 of the coil spring 63 , into the case body 641 through the opening 6414 of the case body 641 , after the projecting portions 623 of the slide cam 62 are aligned with the grooves 6419 of the case body 641 . [0097] The free length L0 of the coil spring 63 is greater than the distance between the bottom face 6415 of the case body 641 and the bottom face 62711 of the spring guide hole 6271 of the slide cam 62 in the initial state of the damper 6 . Accordingly, when the cover 65 is screwed in the opening 6414 of the case body 641 , the coil spring 63 is preloaded between the bottom face 6415 of the case body 641 and the bottom face 62711 of the spring guide hole 6271 of the slide cam 62 . As a result, the slide cam 62 is biased toward the direction of pressing the inclined cam faces 621 of the slide cam 62 against the inclined cam faces 611 of the rotating cam 61 . This causes rotation of the rotating cam 61 , and thereby the inclined faces 629 in the cam face 622 of the slide cam 62 come in contact with the respective step faces 619 in the cam face 612 of the rotating cam 61 . This position becomes the initial position of the inclined cam faces 621 of the slide cam 62 relative to the inclined cam faces 611 of the rotating cam 61 . [0098] Within the case body 641 , the one end 631 of the coil spring 63 is in contact with the bottom face 62711 of the spring guide hole 6271 of the slide cam 62 , and the other end 632 is in contact with the bottom face 6415 of the case body 641 (See FIG. 4(C) ). Thus, it is favorable that both ends 631 and 632 of the coil spring 63 are polishing-processed closed ends so that both ends 631 and 632 of the coil spring 63 are stable in this state. [0099] Owing to the above-described construction, the accelerator pedal unit 1 of the present embodiment makes it possible that a suitable load is applied on a driver's foot during pressing of the accelerator pedal 21 down and the load applied on the driver's foot becomes rapidly larger by enough magnitude to be detected by tactile sensation at the time when the accelerator pedal 21 is pressed to the position where the energy expenditure rate of the automobile deteriorates to the prescribed level (i.e. when the pedal pivot pin 4 rotates to the prescribed angle θ1 in the normal rotation direction α). This will be described in the following. [0100] FIGS. 9(A) , 9 (B) and 9 (C) are views for explaining two-stage damping motion of the damper 6 associated with pressing the accelerator pedal 21 . [0101] As illustrated in FIG. 9(A) , in the state where the accelerator pedal 21 is not pressed, each inclined cam face 621 of the slide cam 62 of the damper 6 is located in the initial position determined by the corresponding step face 619 of the cam face 612 of the rotating cam 61 . [0102] As illustrated in FIG. 9(B) , when the accelerator pedal 21 is pressed, the pedal pivot pin 4 rotates in the normal rotation direction α interlocking with swinging of the accelerator pedal arm 2 . At that time, within the damper 6 , the flat surfaces 423 of the damper connecting section 42 of the pedal pivot pin 4 come in contact with the respective opposed flat surfaces 618 in the inner wall of the rotating cam 61 , so that the rotating cam 61 is rotated in the normal rotation direction α. As a result, the slide cam 62 moves in the direction A of getting away from the rotating cam 61 while only the edge portion 621 A of each inclined cam face 621 is in sliding contact with the first inclined area 611 A of the gentle slope in the corresponding inclined cam face 611 of the rotating cam 61 until the rotating cam 61 rotates to the prescribed angle θ1 in the normal rotation direction α. During this, the coil spring 63 is gradually compressed from the initial preloaded state, so that the coil spring 63 presses more and more strongly the edge portion 621 A of each inclined cam face 621 of the slide cam 62 against the first inclined area 611 A of the corresponding inclined cam face 611 of the rotating cam 61 . Accordingly, the friction resistance, for example, between the edge portion 621 A of the inclined cam face 621 of the slide cam 62 and the first inclined area 611 A in the inclined cam face 611 of the rotating cam 61 gradually increases, and the torque of the rotating cam 61 in the rotation direction about the axis O increases gradually with increase of the angle of rotation of the rotating cam 61 in the normal rotation direction α relative to the slide cam 62 . As a result, rotation of the pedal pivot pin 4 in the normal rotation direction α is damped, and the suitable load is applied on the driver's foot that presses the accelerator pedal 21 . [0103] As illustrated in FIG. 9(C) , when the accelerator pedal 21 is pressed to the position where the energy expenditure rate of the automobile deteriorates to the prescribed level (i.e. when the pedal pivot pin 4 rotates to the prescribed angle θ1 in the normal rotation direction α), then in each inclined cam face 611 of the rotating cam 61 , the whole area of the corresponding inclined cam face 621 of the slide cam 62 comes in contact with the second inclined area 611 B that is steeper than the first inclined area 611 A with respect to the circumferential direction of the pitch circle 615 (the rotation direction of the pedal pivot pin 4 and the like). Accordingly, the slide cam 62 exerts greater force in the direction of resisting rotation of the rotating cam 61 in comparison with the case where the inclined cam faces 621 slide on the first inclined areas 611 A of the gentle slope, and the torque of the rotating cam 61 in the rotation direction about the axis O increases rapidly. As a result, at the time when the accelerator pedal 21 is pressed to the position where the energy expenditure rate of the automobile deteriorates to the prescribed level, the load applied on the driver's foot that presses the accelerator pedal 21 increases rapidly by at least magnitude such that a variation of load can be detected by tactile sensation. [0104] When the driver continues pressing down the accelerator pedal 21 furthermore (i.e. when the pedal pivot pin 4 rotates over the prescribed angle θ1 in the normal rotation direction α), then in each inclined cam face 611 of the rotating cam 61 , the corresponding inclined cam face 621 of the slide cam 62 goes on the second inclined area 611 B that is steeper than the first inclined area 611 A with respect to the circumferential direction of the pitch circle 615 (the rotation direction of the pedal pivot pin 4 and the like), and is in sliding contact with the second inclined area 611 B. During this, the coil spring 63 is further compressed, and presses further strongly the inclined cam faces 621 of the slide cam 62 against the second inclined areas 611 B of the inclined cam faces 611 of the rotating cam 61 . Accordingly, with increase of the angle of rotation of the rotating cam 61 in the normal rotation direction α, the friction resistance, for example, between the inclined cam face 621 of the slide cam 62 and the inclined cam face 611 of the rotating cam 61 increases gradually, and the torque of the rotating cam 61 in the rotation direction about the axis O increases gradually. As a result, also after the rapid increase of the load applied on the driver's foot that presses the accelerator pedal 21 , the load applied on the driver's foot that presses the accelerator pedal 21 further increases gradually as long as the driver continues pressing down the accelerator pedal 21 . Accordingly, the driver can intuitively grasp the continuous worsening of the energy expenditure rate of the automobile through operation of pressing the accelerator pedal 21 without constantly caring about a change of visual information obtained from the meters on the instrument panel. [0105] As describe hereinabove, according to the accelerator pedal unit 1 of the present embodiment, the pedal pivot pin 4 , which is rotated by operation (i.e. pressing and releasing) of the accelerator pedal 21 , is connected to the damper 6 that damps rotation of the pedal pivot pin 4 , and at the time when the pedal pivot pin 4 rotates to the angle θ1, at which the energy expenditure rate of the automobile deteriorates to the prescribed level, in the normal rotation direction α, the force of the damper 6 for damping the rotation of the pedal pivot pin 4 increases rapidly. Accordingly, it is possible that a suitable load is applied on the driver's foot pressing down the accelerator pedal 21 and the load applied on the driver's foot becomes rapidly heavier by at least magnitude that can be detected by tactile sensation when the accelerator pedal 21 is pressed to the position where the energy expenditure rate of the automobile deteriorates to the prescribed level. Thus, the driver can detect a rapid change in operational feeling of pressing the accelerator pedal 21 as a signal for energy-saving driving of the automobile. [0106] Further, when the driver continues pressing down the accelerator pedal 21 thereafter (i.e. when the pedal pivot pin 4 rotates over the prescribed angle θ1 in the normal rotation direction α), the coil spring 63 is further compressed, and the inclined cam faces 621 of the slide cam 62 are further strongly pressed against the second inclined areas 611 B of the inclined cam faces 611 of the rotating cam 61 . Accordingly, with increase of the angle of rotation of the rotating cam 61 in the normal rotation direction α, the friction resistance, for example, between the inclined cam faces 621 of the slide cam 62 and the inclined cam faces 611 of the rotating cam 61 increases furthermore, and the torque of the rotating cam 61 in the rotation direction about the axis O increases furthermore. Accordingly, the load applied on the driver's foot that presses down the accelerator pedal 21 further increases gradually even after the rapid increase of the load. Therefore, the driver can intuitively catch the continuous worsening of the energy expenditure rate of the automobile through operation of pressing the accelerator pedal 21 . [0107] In the present embodiment, each inclined cam face 611 of the rotating cam 61 includes the two inclined areas 611 A and 611 B whose inclination angles with respect to the rotation direction of the pedal pivot pin 4 and the like are different from each other. However, it is possible to form three or more inclined areas, whose inclination angles with respect to the rotation direction of the pedal pivot pin 4 and the like are different from one another, in each inclined cam face 611 of the rotating cam 61 , so that the driver can detect change in the traveling state of the automobile in more-finely-divided stages. [0108] Although, in the present embodiment, each inclined cam face 611 of the rotating cam 61 includes the two inclined areas 611 A and 611 B whose inclination angles with respect to the rotation direction of the pedal pivot pin 4 and the like are different from each other, each inclined cam face 621 of the slide cam 62 may include a plurality of inclined areas whose inclination angles with respect to the rotation direction of the pedal pivot pin 4 and the like are different from one another. Or, for both inclined cam faces 621 of the slide cam 62 and inclined cam faces 611 of the rotating cam 61 , each inclined cam face may include two inclined areas (a first inclined area inclined at a prescribed angle A1 and a second inclined area inclined at an angle A2 larger than the inclination angle A1 of the first inclined area). Then, each inclined face 611 of the rotating cam 61 and the corresponding inclined face 621 of the slide cam 62 may be in sliding contact with each other at their first inclined areas of the gentle slope until the pedal pivot pin 4 rotates to the prescribed angle θ1, and then at their second inclined areas of the steeper slope when the pedal pivot pin 4 rotates over the prescribed angle θ1. [0109] Further, the present embodiment uses the coil spring 63 for biasing the slide cam 62 . However, another elastic body such as rubber, a spring other than the coil spring, or the like may be used. Second Embodiment [0110] In the above-described embodiment (First Embodiment), each inclined cam face of at least one of the rotating cam 61 and the slide cam 62 in the damper 6 includes a plurality of inclined areas whose inclination angles with respect to the rotation direction of the pedal pivot pin 4 and the like are different from one another. However, a damper used in an accelerator pedal unit can have other structure in which friction resistance impeding relative rotation of a rotating cam and a slide cam changes stepwise as the angle of the relative rotation of the rotating cam and the slide cam increases. For example, in the damper 6 , it is possible to use an elastic member having non-linear characteristics, whose elastic coefficient increases stepwise as the rotation angle of the pivot pin 4 increases, so that the resistance force for damping the rotation of the pivot pin 4 increases rapidly at the time when the pivot pin 4 rotates to a prescribed rotation angle. In the following, this case (Second Embodiment) will be described. [0111] First, structure of an accelerator pedal unit 11 according to the present embodiment and structure of a damper 16 used in the accelerator pedal unit 11 will be described. However, in the present embodiment, component parts similar to those in the first embodiment will be given the same reference signs as those in the first embodiment, and their detailed description will be omitted. Similarly to the accelerator pedal unit 1 of the first embodiment, the accelerator pedal unit 11 of the present embodiment comprises: an accelerator pedal arm 2 ; a pedal pivot pin 4 ; a pedal bracket 5 ; retaining ring 7 ; a spring 3 ; and a detection part including a potentiometer and the like (See FIG. 1 ). [0112] Further, this accelerator pedal unit 11 also further comprises: a damper 16 in which resisting force for damping rotation of the pedal pivot pin 4 increases stepwise according to angle θ of rotation of the pedal pivot pin 4 in a normal rotation direction α; and bolts 8 and nuts 9 for fixing the damper 16 to the pedal bracket 5 , in order that, while a suitable load is applied on a driver's foot that presses an accelerator pedal 21 , the load applied on the driver's foot becomes rapidly heavier by at least magnitude that can be detected by tactile sensation at the time when the accelerator pedal 21 is pressed to a position where the energy expenditure rate of the automobile deteriorates to a prescribed level (or when the pedal pivot pin 4 rotates to a prescribed angle θ1 in the prescribed direction α about the axis O of the pedal pivot pin 4 ). However, construction of the damper 16 is different from the damper 6 of the first embodiment. [0113] Similarly to the damper 6 of the first embodiment, the damper 16 is placed between two side plates 52 and 53 , and fixed to the other side plate 53 by tightening nuts 9 on bolts 8 inserted through bolt insertion holes 6421 in flange portions 642 of a case 164 and bolt insertion holes in the other side plate 53 . In this state, the pedal pivot pin 4 is inserted, first the side of a support section 41 of the pedal pivot pin 4 , through a pin support hole 521 of the one side plate 52 until a groove 413 of the support section 41 comes out of a pin support hole 531 of the other side plate 53 . As a result, the pedal pivot pin 4 is rotatably supported in the pin support holes 521 and 531 of the two side plates 52 and 53 at the two positions, i.e. at a support area 425 of a damper connecting section 42 and at the support section 41 , in a state that two flat surfaces 423 of the damper connecting section 42 are contained in the damper 16 fixed to the other side plate 53 . Then, a retaining ring 7 having an outer diameter larger than the pin support hole 531 of the other side plate 53 is fitted in the groove 413 of the support section 41 , to prevent dropping of the pedal pivot pin 4 out of the pedal bracket 5 . [0114] FIG. 10 is an exploded view of the damper 16 according to the present embodiment. Further, FIGS. 11(A) and 11(B) are left and right side views of the damper 16 in an initial state (a state in which the accelerator pedal 21 is not pressed), and FIG. 11(C) an A-A cross-section of FIG. 11(A) . [0115] As illustrated, the damper 16 comprises: a pair of cams (a rotating cam 161 and a slide cam 162 ), whose rotation relative to each other about the axis O causes their inclined cam faces 611 and 621 to slide on and in contact with each other; a combination spring 163 , which biases the slide cam 162 in the direction of pressing the each inclined cam face 1621 of the slide cam 162 against the corresponding inclined cam face 1611 of the rotating cam 161 ; the case 164 , which houses these component parts 161 - 163 and is fixed to the other side plate 53 of the pedal bracket 5 ; and a disk-shaped cover 65 , which seals the case 164 . [0116] Inside the case 164 sealed by the cover 65 , the rotating cam 161 and the slide cam 162 are fitted in each other so that their inclined cam faces 1611 and 621 engage with each other in accordance with the rotation relative between the rotating cam 161 and the slide cam 162 about the common axis O. Although details will be described later, the combination spring 163 is constructed by combining in a nested state two type of coil springs (a first coil spring 163 A and a second coil spring 163 B) having different diameters and different natural lengths from each other, so as to have non-linear spring characteristics in that the spring constant increases at the time when the compression amount reaches a prescribed value. This combination spring 163 is placed between a bottom face 62711 of a spring guide hole 6271 formed in the slide cam 162 and a groove bottom 16417 C of a groove 16417 formed in the bottom portion 16415 of the case 164 , so that a cam face 1622 of the slide cam 162 is pressed against a cam face 1612 of the rotating cam 161 by the restoring force of the combination spring 163 . In the initial state of the damper 16 , each inclined cam face 1621 of the slide cam 162 is located at a prescribed position (initial position) relative to the corresponding inclined cam face 1611 of the rotating cam 161 , owing to biasing by the combination spring 163 preloaded (the first coil spring 163 A preloaded). [0117] In the above-described structure, when the rotating cam 161 is rotated in the normal rotation direction α relative to the slide cam 162 while constraining rotational movement of the slide cam 162 relative to the case 164 , then the slide cam 162 moves in the direction of getting away from the rotating cam 161 (in the direction toward the bottom portion 16415 of the case 164 ) along a cam guide portion 613 of the rotating cam 161 while each inclined cam face 1621 slides on and in contact with the corresponding inclined cam face 1611 of the rotating cam 61 . At this time, the distance between the bottom face 62711 of the spring guide hole 6271 of the slide cam 62 and the groove bottom 16417 C of the groove 16417 in the bottom portion 16415 of the case 164 becomes gradually smaller, and therefore the combination spring 163 is further compressed. As a result, the combination spring 163 presses more strongly the inclined cam faces 1621 of the slide cam 162 against the inclined cam faces 1611 of the rotating cam 161 , and presses more strongly a bottom face 617 of the rotating cam 161 against a seating face 657 (See FIG. 6 ) of the cover 65 . Accordingly, with increase of the angle of rotation θ of the rotating cam 61 in the normal rotation direction a relative to the slide cam 162 , friction resistance, for example, between the inclined cam faces 1621 of the slide cam 162 and the inclined cam faces 1611 of the rotating cam 161 and between the bottom face 167 of the rotating cam 161 and the seating face 657 of the cover 65 increases gradually, and the torque of the rotating cam 161 in the rotation direction about the axis O increases gradually. [0118] When the rotating cam 161 is further rotated in the normal rotation direction α relative to the slide cam 162 , the slide cam 162 further moves toward the bottom portion 16415 of the case 164 along the cam guide portion 613 of the rotating cam 161 while rotating relative to the rotating cam 161 . As a result, the distance between the bottom face 62711 of the spring guide hole 6271 of the slide cam 162 and the groove bottom 16417 C of the bottom portion 16415 of the case 164 becomes gradually smaller furthermore, and the combination spring 163 is further compressed. At the time when the rotating cam 161 rotates to the prescribed angle θ1 in the normal rotation direction α, the compression amount of the combination spring 163 reaches the prescribed value where the spring constant increases. Thus, at the time when the rotation cam 161 rotates to the prescribed angle θ1 in the normal direction α, the restoring force of the combination spring 163 increases rapidly by the magnitude corresponding to the increment of the spring constant. Accordingly, the friction resistance, for example, between the inclined cam faces 1621 of the slide cam 162 and the inclined cam faces 1611 of the rotating cam 161 and between the bottom face 617 of the rotating cam 161 and the bottom face 657 of the cover 65 increases rapidly. Thereby, the torque of the rotating cam 61 in the rotation direction about the axis O increases rapidly at the time when the rotating cam 161 rotates to the prescribed angle θ1 in the normal rotation direction α, and thereafter the torque increases gradually with increase of the rotation angle θ of the rotating cam 161 in the normal rotation direction α relative to the slide cam 162 . [0119] During this, when rotation of the rotating cam 161 is once stopped at any point in time, the inclined cam faces 1621 of the slide cam 162 come to rest on the inclined cam faces 1611 of the rotating cam 161 . At that time, friction resistance is produced in the direction of resisting the tendency of the combination spring 163 toward elongation, and the torque of the rotating cam 161 in the rotating direction about the axis O decreases rapidly. [0120] Further, when the rotating cam 161 is rotated in the reverse rotation direction β, the slide cam 162 moves in the direction of getting close to the rotating cam 161 along the cam guide portion 613 of the rotating cam 161 while the inclined cam faces 1621 slide on the inclined cam faces 1611 of the rotating cam 161 . As a result, the distance between the bottom face 62711 of the spring guide hole 6271 of the slide cam 162 and the groove bottom 16417 C in the bottom portion 16415 of the case 164 becomes gradually greater. And thus the combination spring 163 returns (elongates) to the initial state, and the friction resistance, for example, between the inclined cam faces 1621 of the slide cam 162 and the inclined cam faces 1611 of the rotating cam 161 decreases gradually. Accordingly, with decrease of the rotation angle θ of the rotating cam 161 in the normal rotation direction α, the torque of the rotating cam 161 in the rotation direction about the axis O decreases gradually. [0121] The above-described damper 16 has hysteresis characteristics suitable to use as a hysteresis generation mechanism (hys-unit) that applies a suitable load at the time of pressing the accelerator pedal 21 and reduces load while the accelerator pedal 21 is held at a certain position. When the damper 16 is assembled in the accelerator pedal unit 11 , the damper 16 can not only realize natural accelerator pedal operation feeling while generating natural acceleration force, but also generate a rapid change in operational feeling of pressing the accelerator pedal 21 , which can be detected as a signal for energy-saving driving of an automobile, at the time when the accelerator pedal 21 is pressed excessively. Each of the component parts 161 - 164 , 165 of the damper 16 realizing such functions will be described. [0122] FIG. 12(A) is a view for explaining the structure of the combination spring 163 . Further, FIG. 12(B) is a view illustrating a state of the combination spring 163 before increase of the spring constant, and FIG. 12(C) is a view illustrating a state of the combination spring 163 with the spring constant increased. [0123] The combination spring 163 is constructed by combining in a nested state the two type of coil springs (the first coil spring 163 A and the second coil spring 163 B) having different diameters and different natural lengths from each other, so as to have the non-linear spring characteristics in that the spring constant increases at the time when the compression amount reaches the prescribed value. In detail, as illustrated in FIG. 12(A) , the first spring 163 A and the second spring 163 B are prepared in advance such that the first spring 163 A has the natural length LA0 greater than the distance L4 (See FIG. 11(C) ) between the bottom face 62711 of the spring guide hole 6271 of the slide cam 162 and the groove bottom 16417 C of the groove 16417 formed in the bottom portion 16415 of the case body 1641 in the initial state of the damper 16 and the second spring 163 B has the natural length LB0 smaller than the distance L4 between the bottom face 62711 of the spring guide hole 6271 of the slide cam 162 and the groove bottom 16417 C of the groove 16417 formed in the bottom portion 16415 of the case body 1641 in the initial state of the damper 16 and has the inner diameter r2 larger than the outer diameter r1 of the first coil spring 163 A. Then, as illustrated in FIG. 12(B) , the combination spring 163 is constructed by inserting the first coil spring 163 A into the inside of the second coil spring 163 B so that the outer periphery of the first coil spring 163 A is surrounded by the second coil spring 163 B. [0124] When the combination spring 163 is compressed in the direction of axis O, only the first coil spring 163 A protruding from at least one end 1632 B of the second coil spring 163 B is compressed ( FIG. 12(B) ) up to the compression amount corresponding to the difference of the natural lengths (LA0-LB0) between the first and second coil springs 163 A and 163 B, and thus the combination spring 163 functions as a compression spring having the same spring constant as that of the first coil spring 163 A. When the compression amount becomes larger than that, both the first coil spring 163 A and the second coil spring 163 B are compressed (FIG. 12 (C)), and thus the combination spring 163 functions as a compression spring having a spring constant corresponding to the sum of the spring constants of the first and second coil springs 163 A and 163 B. [0125] The combination spring 163 having the non-linear spring characteristics described above is placed as follows in the inside of the below-described case body 1641 in the initial state of the damper 16 . The first coil spring 163 A is place in a preloaded state between the bottom face 62711 of the spring guide hole 6271 formed in the slide cam 162 and the groove bottom 16417 C of the groove 16417 formed in the bottom portion 16415 of the case body 1641 so that the cam face 1622 of the slide cam 162 is pressed against the cam face 1612 of the rotating cam 161 . In the initial state of the damper 16 , each inclined cam face 1621 of the slide cam 162 is pressed against the cam face 1612 of the rotating cam 161 being biased by the preloaded first coil spring 163 A, so as to be located in initial position determined by each step face 619 (See FIG. 14(E) ) in the cam face 1612 of the rotating cam 161 . On the other hand, the second coil spring 163 B is placed in an unloaded state between the bottom face 62711 of the spring guide hole 6271 of the slide cam 162 and the groove bottom 16417 C of the groove 14617 formed in the bottom portion 16415 of the case 164 . In other words, the combination spring 163 functions as a spring having the same spring constant as that of the first coil spring 163 A in the initial state of the damper 16 . When the combination spring 163 is compressed by more than the difference of the natural lengths (LA0-LB0) between the first and second coil springs 163 A and 163 B, the combination spring 163 functions as a spring having the spring constant larger than that in the initial state of the damper 16 . [0126] In the present embodiment, the first coil spring 163 A having the greater natural length than that of the second coil spring 163 B is placed in the inside of the second coil spring 163 B in the nested state. On the contrary, it is possible that the second coil spring 163 B is placed in the inside of the first coil spring 163 A having the greater natural length than that of the second coil spring 163 B in a nested state. [0127] Further, in the inside of the below-described case body 1641 , one end 1631 A of the first coil spring 163 A is in contact with the bottom face 62711 of the spring guide hole 6271 of the slide cam 162 , and the other end 1632 A is in contact with the groove bottom 16417 C of the groove 16417 formed in the bottom portion 16415 of the case body 1641 (See FIG. 11(C) ). Thus, it is favorable that both ends 1631 A and 1632 A of the first coil spring 163 A are polishing-processed closed ends so that both ends 1631 A and 1632 A of the first coil spring 163 A are stable in the contact state. This is same for both ends 1631 B and 1632 B of the second coil spring 163 B. [0128] FIGS. 13(A) and 13(B) are left and right side views of the case 164 , and FIG. 13(C) a B-B cross-section of FIG. 13(A) . [0129] As illustrated, the case 164 integrally comprises: the case body 1641 of a bottomed cylindrical shape; and the two flange portions 642 projecting in radial directions from the outer periphery 6412 of the case body 1641 . [0130] The cover 65 is fitted in an opening 6414 of the case body 1641 . In the inner periphery of the opening 6414 , is formed a threaded portion 6416 into which a threaded portion 652 of the outer periphery 651 of the cover 65 is screwed. By tightening of this threaded portion 6416 and the threaded portion 652 in the outer periphery 651 of the cover, the cover 65 is fitted in the opening 6414 of the case body 641 while preloading the first coil spring 163 A housed in the case body 1641 . In an edge portion of the case body 1641 , a plurality of recessed portions 6411 for welding, which are used for fixing the cover 65 fitted in the opening 6414 , are formed at almost regular angular intervals about the axis O of the case body 1641 . [0131] In the central area of the bottom portion 16415 of the case body 1641 , are formed a through-hole 6413 , through which the axis O of the case body 1641 passes, and a ring-shaped groove 16417 surrounding the outer circumference of the through-hole 6413 . The one end 1631 A of the first coil spring 163 A is set on the inner wall surface 16417 A of the groove 16417 on the inner diameter side, so that the inner wall surface 16417 A functions as an inner-diameter spring guide for fixing the position of this end 1631 A. On the other hand, the one end 1631 B of the second coil spring 163 B is set on the inner wall surface 16417 B of the groove 14617 on the outer diameter side, so that the inner wall surface 16417 B functions as an outer-diameter spring guide for fixing the position of this end 1631 B. [0132] Further, in the inner periphery 6418 of the case body 1641 , are formed three grooves 6419 along the direction of the axis O of the case body 1641 at almost regular angular intervals about the axis O of the case body 1641 . One end of each groove 6419 passes through the opening-side end face 6410 A of the case body 1641 . When the slide cam 162 is inserted through the opening 6414 of the case body 1641 , projecting portions 623 on the outer periphery 624 of the slide cam 162 are slidably inserted into these grooves 6419 . By this, rotational movement of the slide cam 162 relative to the case 164 is constrained. In other words, rotational movement of the slide cam 162 relative to the pedal bracket 5 is constrained. [0133] Although, in the present embodiment, the three grooves 6419 are formed in the inner periphery 6418 of the case body 1641 at almost regular angular intervals about the axis O, the number and layout of the grooves 6419 are determined in accordance with the number and layout of the projecting portions 623 of the slide cam 162 that is used. [0134] On the other hand, the two flange portions 642 are formed integrally with the outer periphery 6412 of the case body 1641 so as to project outward from both sides of the end face 6410 A on the opening side of the case body 1641 . In these flange portions 642 , are formed the bolt insertion holes 6421 for inserting the bolts 8 at positions that correspond to the respective bolt insertion holes in the other side plate 53 of the pedal bracket 5 when a through-hole 653 formed in the central area of the cover 65 fitted in the opening 6414 of the case body 1641 is aligned with the pin insertion hole 531 of the other side plate 53 of the pedal bracket 5 . [0135] The cover 65 has similar construction to the cover 6 of the first embodiment (See FIG. 6 ). That is to say, in the outer periphery 651 of the cover 65 , is formed the threaded portion 652 that is screwed into the threaded portion 6416 formed in the opening 6414 of the case body 1641 . In one surface (the surface to be faced toward the outside of the case body 1641 ) 654 of the cover 65 , is formed a hexagon socket 656 for inserting a tool for rotating the cover 65 relative to the case body 1641 . On the other surface (the rear surface to be faced toward the inside of the case body 1641 ) 655 of the cover 65 , is formed a seating face 657 with which the bottom face 617 of the rotating cam 161 is in sliding contact in the course of rotation. By rotating the tool inserted in the hexagon socket 656 in the surface 654 of the cover 65 , the threaded portion 652 formed in the outer periphery 651 of the cover 65 is tightened into the threaded portion 6416 formed in the opening 6414 of the case body 1641 , and thereby the bottom face 617 of the rotating cam 161 is pressed by the seating face 657 of the cover 65 . As a result, the rotating cam 161 and the slide cam 162 are pressed into initial positions within the case body 1641 . At that time, only the first coil spring 163 , whose natural length is greater than the distance between the bottom face 62711 of the spring guide hole 6271 of the slide cam 162 and the groove bottom 16417 C of the groove 16417 formed in the bottom portion 16415 of the case body 1641 , is preloaded between the groove bottom 16417 C of the bottom portion 16415 of the case body 1641 and the bottom face 62711 (See FIG. 15(D) ) of the spring guide hole 6271 of the slide cam 162 . [0136] Further, in the central area of the cover 65 , is formed the through-hole 653 having the inner diameter R2 larger than the outer diameter R1 of the damper connecting section 42 of the pedal pivot pin 4 . In an assembled state of the damper 16 , the axis O of the case body 1641 passes through the through-hole 653 , the inside of the rotating cam 161 , and the through-hole 6413 in the bottom portion 16415 of the case body 1641 (See FIG. 11(C) ). The pedal pivot pin 4 is inserted, first the side of the support section 41 , into the through-hole 653 , and passes through the inside of the rotating cam 161 , so as to protrude from the through-hole 6413 of the bottom portion 16415 of the case body 1641 . [0137] FIGS. 14(A) , 14 (B) and 14 (C) are a front view and left and right side views of the rotating cam 161 , FIG. 14(D) a D-D cross-section of FIG. 14(C) , and FIG. 14(E) a view illustrating schematically a profile shape of the cam face 1612 on the pitch circle 615 centering at the axis O. [0138] As illustrated, the rotating cam 161 has a stepped cylindrical shape including the cam guide portion 613 as a smaller-diameter portion and a cam portion 1610 as a large-diameter portion that are formed integrally. The cam guide portion 613 is an inner-diameter guide for the slide cam 162 and inserted into the inside of the slide cam 162 . On the other hand, the cam portion 1610 has the cam face 1612 on which the inclined cam faces 1621 of the slide cam 162 slide. [0139] Into the inside of the rotating cam 161 , the pedal pivot pin 4 is inserted from one end face 616 toward the other end face (bottom face), after passing through the through-hole 653 of the cover 65 . In an inner wall 614 of the rotating cam 161 , are formed two flat surfaces 618 facing each other at a width-across-flat T1 corresponding to the width-across-flat t1 of the damper connecting section 42 of the pedal pivot pin 4 . When the damper connecting section 42 of the pedal pivot pin 4 is inserted into the inside of the rotating cam 161 , these flat surfaces 618 come in contact with the corresponding flat surfaces 423 of the damper connecting section 42 of the pivot pin 4 , so that the torque of the pedal pivot pin 4 is transmitted to the rotating cam 161 . As a result, associated with rotation of the pedal pivot pin 4 in both directions α and β caused by operation of the accelerator pedal 21 , the rotating cam 161 also rotates in both directions α and β about the axis O while generating friction resistance, for example, between the inclined cam faces 1611 formed in the cam face 1612 and the inclined cam faces 1621 of the slide cam 162 . [0140] On the pitch circle 615 centering at the axis O, the cam face 1612 (the face on the side of the cam guide portion 613 ) of the cam portion 1610 periodically repeats concave forms and convex forms in the direction of the axis O. In detail, in the cam face 1612 of the cam portion 1610 , three inclined cam faces 1611 inclined at a prescribed angle W to the circumferential direction of the pitch circle 615 (the rotation direction of the pedal pivot pin 4 and the like) are formed at almost regular angular intervals about the axis O. Further, between each pair of adjacent inclined cam faces 1611 , is formed a step face 619 for determining the initial position of an inclined cam face 1621 of the slide cam 162 . When the rotating cam 161 rotates in the normal rotation direction α relative to the slide cam 162 , each inclined face 1621 of the slide cam 162 goes sliding on the corresponding inclined cam 1611 in the direction of getting away from the initial position determined by the corresponding step face 619 . When the rotating cam 161 rotates in the reverse rotation direction β relative to the slide cam 162 , each inclined cam face 1621 of the slide cam 162 goes sliding on the corresponding inclined cam face 1611 toward the initial position determined by the corresponding step face 619 . [0141] FIGS. 15(A) , 15 (B) and 15 (C) are a front view, a back view and a side view of the slide cam 162 , FIG. 15(D) an E-E cross-section of FIG. 15(A) , and FIG. 15(E) a view illustrating schematically a profile shape of the cam face 1622 on the pitch circle 625 centering at the axis O. [0142] The slide cam 162 comprises: a cylindrical cam portion 1620 , into which the cam guide portion 613 of the rotating cam 161 is slidably inserted; and projecting portions 623 formed on the outer periphery 624 of the cam portion 1620 along the axis O of the cam portion 1620 . [0143] In the inner periphery of the cam portion 1620 , is formed a stepped hole 627 having a spring guide hole 6271 as a large-diameter portion on the side of a bottom face 626 of the cam portion 1620 . This spring guide hole 6271 encloses the one end 1631 A of the first coil spring 163 A, and the bottom face 62711 of the spring guide hole 6271 receives the one end 1631 A of the first coil spring 163 A from the initial state of the damper 16 . Further, the spring guide hole 6271 encloses the one end 1631 B of the second coil spring 163 B, and in the course of operation of the damper 16 , guides the one end 1631 B of the second coil spring 163 B toward the bottom face 62711 . [0144] On the pitch circle 625 centering at the axis O, the cam face (the face opposite to the bottom face 626 ) 622 of the cam portion 1620 periodically repeats concave forms and convex forms in the direction of the axis O. In detail, in the cam face 1622 of the cam portion 1620 , three inclined cam faces 1621 inclined at nearly the same angle W as that of the inclined cam faces 1611 of the rotating cam 161 to the circumferential direction of the pitch circle 625 (the rotation direction of the pedal pivot pin 4 and the like) are formed at almost regular angular intervals about the axis O. Further, for each inclined cam face 1621 , are formed a flat face 628 which follows the inclined cam face 1621 , and an inclined face 629 that comes in contact with a step face 619 in the cam face 1612 of the rotating cam 161 . [0145] When the cam guide portion 613 of the rotating cam 161 is inserted into the inside of the cam portion 1620 in a state that the cam face 1622 of the cam portion 1620 is faced toward the cam face 1612 of the rotating cam 161 , the cam guide portion 613 of the rotating cam 161 protrudes from the side of the bottom face 626 of the cam portion 1620 . The cam guide portion 613 protruding from the side of the bottom face 626 of the cam portion 1620 is inserted into the inside of the combination spring 163 (the inside of the first coil spring 163 A placed within the second coil spring 163 B), and the spring guide hole 6271 of the cam portion 1620 is made to enclose the one end 1631 A of the first coil spring 163 A and the one end 1631 B of the second coil spring 163 B. [0146] The combination spring 163 , the slide cam 162 and the rotating cam 161 , which are assembled in the above way, are housed, first the side of the other end 1632 A of the first coil spring 163 A, into the case body 1641 through the opening 6414 of the case body 1641 , after the projecting portions 623 of the slide cam 162 are aligned with the grooves 6419 in the inner periphery 6418 of the case body 1641 . [0147] The free length LA0 of the first coil spring 163 A is greater than the distance L4 between the groove bottom 16417 C of the groove 16417 formed in the bottom portion 16415 of the case body 1641 and the bottom face 62711 of the spring guide hole 6271 of the slide cam 162 in the initial state of the damper 16 . Accordingly, when the cover 65 is screwed in the opening 6414 of the case body 1641 , only the first coil spring 163 A is preloaded between the groove bottom 16417 C of the bottom portion 16415 of the case body 1641 and the bottom face 62711 of the spring guide hole 6271 of the slide cam 162 . On the other hand, the free length LB0 of the second coil spring 163 B is smaller than the distance L4 between the groove bottom 16417 C of the groove 16417 formed in the bottom portion 16415 of the case body 1641 and the bottom face 62711 of the spring guide hole 6271 of the slide cam 162 in the initial state of the damper 16 . Thus, the second coil spring 163 B is not compressed only by screwing the cover 65 in the opening 6414 of the case body 1641 . Thus, in the initial state of the damper 16 , only the first coil spring 163 A biases the slide cam 162 toward the direction of pressing the inclined cam faces 1621 of the slide cam 162 against the inclined cam faces 1611 of the rotating cam 161 . This causes rotation of the rotating cam 161 , and thereby the inclined cam faces 1621 in the cam face 1622 of the slide cam 162 come in contact with the respective step faces 619 in the cam face 1612 of the rotating cam 161 . This position becomes the initial position of the inclined cam faces 1621 of the slide cam 162 relative to the inclined cam faces 1611 of the rotating cam 161 . Thereafter, when, due to rotation of the rotating cam 161 , the slide cam 162 moves toward the bottom portion 16415 of the case 164 and reaches the prescribed position, the first coil spring 163 A and the second coil spring 163 B are both compressed between the groove bottom 16417 C of the bottom portion 16415 of the case body 1641 and the bottom face 62711 of the spring guide hole 6271 of the slide guide 162 . [0148] Owing to the above-described construction, the accelerator pedal unit 11 of the present embodiment makes it possible that a suitable load is applied on a driver's foot during pressing down of the accelerator pedal 21 and the load applied on the driver's foot becomes rapidly larger by magnitude that can be detected by tactile sensation at the time when the accelerator pedal 21 is pressed to the prescribed position where the energy expenditure rate of the automobile deteriorates to the prescribed level (i.e. when the pedal pivot pin 4 rotates to the prescribed angle θ1 in the normal rotation direction α), as described in the following. [0149] FIGS. 16-18 are views for explaining two-stage damping motion of the damper 16 associated with pressing the accelerator pedal 21 . [0150] As illustrated in FIG. 16 , in the initial state of the damper 16 (the state where the accelerator pedal 21 is not pressed), each inclined cam face 1621 of the slide cam 162 of the damper 16 is located in the initial position determined by the corresponding step face 619 of the cam face 1612 of the rotating cam 161 . [0151] When the accelerator pedal 21 is pressed down, the pedal pivot pin 4 rotates in the normal direction α interlocking with swinging of the accelerator pedal arm 2 . At that time, within the damper 16 , the flat surfaces 423 of the damper connecting section 42 of the pedal pivot pin 4 come in contact with the respective opposed flat surfaces 618 in the inner wall of the rotating cam 161 , so that the rotating cam 161 is rotated in the normal rotation direction α. Until the rotating cam 61 rotates to the prescribed angle θ1 in the normal rotation direction α, the slide cam 162 moves in the direction A of getting away from the rotating cam 161 (the direction toward the bottom portion 16415 of the case 164 ) while each inclined cam face 1621 is in sliding contact with the corresponding inclined cam face 1611 of the rotating cam 161 . During this, only the first coil spring 163 A is gradually compressed from the initial preloaded state, so that each inclined cam face 1621 of the slide cam 162 is pressed more and more strongly against the corresponding inclined cam face 1611 of the rotating cam 161 . In other words, the combination spring 163 functions as a compression spring having the same spring contact as that of the first coil spring 163 A. Accordingly, the friction resistance, for example, between the inclined cam faces 1621 of the slide cam 162 and the inclined cam faces 1611 of the rotating cam 161 gradually increases, and the torque of the rotating cam 161 in the rotation direction about the axis O increases gradually with increase of the rotation angle θ of the rotating cam 161 in the normal rotation direction α relative to the slide cam 162 . As a result, rotation of the pedal pivot pin 4 in the normal rotation direction α is damped, and the suitable load is applied on the driver's foot that presses the accelerator pedal 21 . [0152] As illustrated in FIG. 17 , when the accelerator pedal 21 is pressed to the position where the energy expenditure rate of the automobile deteriorates to the prescribed level (i.e. when the pedal pivot pin 4 rotates to the prescribed angle θ1 in the normal rotation direction α), the slide cam 162 moves toward the bottom portion 16415 of the case 164 up to the position where the one end 1631 B of the second coil spring 163 B comes in contact with the bottom face 62711 of the spring guide hole 6271 of the slide cam 162 , with each inclined cam face 1621 in sliding contact with the corresponding inclined cam face 1611 of the rotating cam 161 . As a result, at the time when the rotating cam 161 rotates to the prescribed angle θ1 in the normal rotation direction α, also the second coil spring 163 B together with the first coil spring 163 A starts to bias the slide cam 162 so as to press each inclined cam face 1621 of the slide cam 162 against the corresponding inclined cam face 1611 of the rotating cam 161 . In other words, the combination spring 163 functions as a compression spring that has a spring constant corresponding to the sum of the spring constants of the first and second coil springs 163 A and 163 B. Accordingly, each cam face 1621 of the slide cam 162 is pressed against the corresponding cam face 1611 of the rotating cam 161 and the bottom face 617 of the rotating cam 161 against the seating face 657 of the cover 65 by force that is greater by additional biasing force of the second coil spring 163 B than the force at the time when only the first coil spring 163 A biases the slide cam 162 , and thus the torque of the rotating cam 161 in the rotation direction about the axis O increases rapidly. Thus, at the time when the accelerator pedal 21 is pressed to the position where the energy expenditure rate of the automobile deteriorates to the prescribed level, the load applied on the driver's foot that presses the accelerator pedal 21 becomes rapidly larger by at least magnitude such that a variation of load can be detected by tactile sensation. [0153] As illustrated in FIG. 18 , when the driver continues pressing down the accelerator pedal 21 furthermore (i.e. when the pedal pivot pin 4 rotates over the prescribed angle θ1 in the normal rotation direction α), then the slide cam 162 moves toward the bottom portion 16415 of the case 164 with each inclined cam face 1621 in sliding contact with the corresponding inclined cam face 1611 of the rotating cam 161 , so that the first coil spring 163 A and the second coil spring 163 B are compressed furthermore. Accordingly, the inclined cam faces 1621 of the slide cam 162 are pressed further strongly against the inclined cam faces 1611 of the rotating cam 161 , and the bottom face 617 of the rotating cam 161 is pressed further strongly against the seating face 657 of the cover 65 . Accordingly also after increase of the spring constant, the friction resistance, for example, between the inclined cam faces 1621 of the slide cam 162 and the inclined cam faces 1611 of the rotating cam 161 further increases gradually with increase of the rotation angle θ of the rotating cam 161 in the normal rotation direction α, and the torque of the rotating cam 161 in the rotation direction about the axis O increases gradually. As a result, also after the rapid increase of the load applied on the driver's foot that presses down the accelerator pedal 21 , the load applied on the driver's foot that presses the accelerator pedal 21 further increases gradually as long as the driver continues pressing down the accelerator pedal 21 . Accordingly, the driver can intuitively grasp the continuous worsening of the energy expenditure rate of the automobile through operation of pressing the accelerator pedal 21 without constantly caring about a change of visual information obtained from the meters on the instrument panel. [0154] As described hereinabove, according to the accelerator pedal unit 11 of the present embodiment, the pedal pivot pin 4 , which is rotated by operation (i.e. pressing and releasing) of the accelerator pedal 21 , is connected to the damper 16 whose resisting force for damping rotation of the pedal pivot pin 4 increases stepwise according to the rotation angle θ of the pedal pivot pin 4 in the normal rotation direction α. At the time when the pedal pivot pin 4 rotates in the normal rotation direction α to the prescribed rotation angle θ1 at which the energy expenditure rate of the automobile deteriorates to the prescribed level, the damper 16 rapidly increases the force of damping rotation of the pedal pivot pin 4 . Thus, it is possible that, while a suitable load is applied on the driver's foot pressing the accelerator pedal 21 , when the accelerator pedal 21 is pressed to the position where the energy expenditure rate of the automobile worsens to the prescribed level, the load applied on the driver's foot becomes rapidly heavier by at least magnitude that can be detected by tactile sensation. Thus, the driver can detect a rapid change in operational feeling of pressing the accelerator pedal 21 as a signal for energy-saving driving of the automobile while driving. [0155] Further, when the driver continues pressing down the accelerator pedal 21 (i.e. when the pedal pivot pin 4 rotates over the prescribed angle θ1 in the normal rotation direction α), the friction resistance, for example, between the inclined cam faces 1621 of the slide cam 162 and the inclined cam faces 1611 of the rotating cam 161 increases furthermore with increase of the rotation angle θ of the rotating cam 161 in the normal rotation direction α, and the torque of the rotating cam 161 in the rotation direction about the axis O increases furthermore. Accordingly, the load applied on the driver's foot that presses down the accelerator pedal 21 further increases gradually even after the rapid increase of the load. Therefore, the driver can intuitively grasp the continuous worsening of the energy expenditure rate of the automobile through operation of pressing the accelerator pedal 21 . [0156] In the present embodiment, the non-linear spring whose elastic constant increases at the time when the spring is compressed to the prescribed compression amount is constructed as the combination spring in which two coil springs 163 A and 163 B having different natural lengths from each other are arranged in the nested state, and this non-linear spring biases the slide cam 162 . At the time when the rotating cam 161 rotates to the prescribed angle θ1 in the normal rotation direction α, the torque of the pedal pivot pin 4 in the rotation direction about the axis O is increased by at least magnitude such that the driver can detect as a change in operational feeling of the accelerator pedal 21 . However, this is not indispensable. [0157] For example, the combination spring 163 can be constructed by arranging three or more coil springs having different natural lengths from each other in a nested state. In that case, the driver can detect change in the traveling state of the automobile in more-finely-divided stages. [0158] Further, instead of the combination spring 163 comprising the two spring coils 163 A and 163 B having the different natural lengths from each other, it is possible to use a non-linear spring such as an irregular pitch coil spring or a tapered coil spring, whose spring constant changes stepwise in the course of compression. When such a non-linear spring is used, the spring constant of the non-linear spring increases in a prescribed range of rotation angle including the time when the rotating cam 161 rotates to the prescribed angle θ1 in the normal rotation direction α. Therefore, the torque of the pedal pivot pin 4 in the rotation direction about the axis O can be increased by increment such that the driver can detect a change in operational feeling of the accelerator pedal 21 at the time when the rotating cam 161 rotates to the prescribed rotation angle θ1 in the normal rotation direction α. [0159] In the present embodiment, the coil springs 163 A and 163 B are used for biasing the slide cam 162 . However, another elastic body such as rubber, a spring other than the coil spring, or the like may be used. [0160] In the above-described first and second embodiments, the outer periphery 421 of the damper connecting section 42 of the pedal pivot pin 4 is formed to have the two flat surfaces and the opposed two flat surfaces 618 are formed in the inner wall 614 of the rotating cam 61 , 161 of the damper 6 , 16 , so that the rotating cam 61 , 161 of the damper 6 , 16 rotates interlocking with rotation of the pedal pivot pin 4 . However, this is not indispensable. It is sufficient that the outer periphery 421 of the damper connecting section 42 of the pedal pivot pin 4 and the inner wall 614 of the rotating cam 61 , 161 of the damper 6 , 16 include respective surfaces that interfere with each other, and rotation of the pedal pivot pin 4 is transmitted to the rotating cam 61 , 161 of the damper 6 , 16 by means of contact between these surfaces. For example, it is possible that the outer periphery 421 of the damper connecting section 42 of the pedal pivot pin 4 and the inner wall 614 of the rotating cam 61 , 161 of the damper 6 , 16 are each formed to have one flat surface or three or more flat surfaces so that the respective surfaces of the damper connecting section 42 and the inner wall 614 of the rotating cam 61 , 161 come in contact with each other when the pedal pivot pin 4 rotates. Or, both a cross-section shape of the damper connecting section 42 of the pedal pivot pin 4 and a contour shape of the inner wall 614 of the rotating cam 61 , 161 of the damper 6 , 16 can be polygonal shapes. Or, one or more recessed portions may be formed in the outer periphery 421 of the pedal pivot pin 4 and one or more projecting portions to fit in these recessed portions may be formed in the inner wall 614 of the rotating cam 61 , 161 of the damper 6 , 16 . [0161] Further, the retaining ring 7 is used for preventing dropping-off of the pedal pivot pin 4 in the above-described first and second embodiments. However, another part for preventing dropping-off of the pedal pivot pin 4 can be used instead of the retaining ring 7 . For example, in the case of using a bush nut or the like, which can be fixed without a groove, it is not necessary to form the groove 413 in the support section 41 of the pedal pivot pin 4 . [0162] The above-described first and second embodiments take the examples of the accelerator pedal units 1 and 11 for an automobile. However, the present invention can be applied to operation units of various apparatuses such as musical instruments, game machines, various devices, and the like without limiting to an accelerator pedal unit 1 , 11 , as far as it is useful to give, as a signal of occurrence of a predetermined event, a change in operational feeling of an operating part such as a pedal and a steering wheel to an operator at the time when the operator moves the operating part to a prescribed position by manual operation with hand, foot, or the like. In the damper 6 of the first embodiment, the number of the inclined cam faces, the inclination angles of the plurality of inclined areas included in the inclined cam faces, and sequential order of the inclined areas can be determined suitably depending on the intended use of the operation unit. Similarly, in the damper 16 of the second embodiment, the number of coil springs combined in the nested state as components of the combination spring 163 can be determined suitably depending on the intended use of the operation unit. [0163] Further, in the damper 6 of the first embodiment, it is possible to use the combination spring 163 of the damper 16 of the second embodiment instead of the coil spring 63 . By this, the stepwise change in the resisting force for damping rotation of the pedal pivot pin 4 according to the rotation angle θ of the pedal pivot pin 4 in the normal rotation direction α can be realized by a plurality of inclined areas of different inclination angles provided in the inclined cam faces 611 of the rotating cam 61 and a plurality of coil springs of different coil lengths as elements of the combination spring 163 , and thus the resisting force can be changed stepwise in more-finely-divided stages. Accordingly, the driver can detect a change in the traveling state of the automobile in more-finely-divided stages. INDUSTRIAL APPLICABILITY [0164] The present invention can be widely applied to cases where it is beneficial for a user operating manually an operating part to grasp intuitively occurrence of a prescribed event. REFERENCE SIGNS LIST [0000] 1 , 11 : accelerator pedal unit; 2 : accelerator pedal arm; 3 : spring; 4 : pedal pivot pin; 5 : pedal bracket; 6 , 16 : damper; 7 : retaining ring; 8 : bolt; 9 : nut; 21 : accelerator pedal; 41 : support section; 42 : damper connecting section; 43 : pedal arm fixing section; 51 : bottom plate; 52 , 53 : side plate; 61 , 161 : rotating cam; 62 , 162 : slide cam; 63 : coil spring; 64 , 164 : case; 65 : cover; 411 : outer periphery of dropping-off preventing section; 412 : end face of pedal pivot pin; 413 : groove; 421 : outer periphery of damper connecting section; 423 : flat surface; 425 : support area; 431 : outer periphery of pedal arm fixing section; 422 , 432 : step surface of pedal pivot pin; 521 , 531 : pin support hole; 610 , 1610 : cam portion; 611 , 1611 : inclined cam face; 611 A: first inclined area; 611 B: second inclined area; 612 , 1612 : cam face; 613 : cam guide portion; 614 : inner wall of rotating cam; 615 : pitch circle; 616 , 617 : end face of rotating cam; 618 : flat surface of rotating cam's inner wall; 619 : step face; 620 , 1620 : cam portion; 621 , 1621 : inclined cam face; 622 , 1622 : cam face; 623 : projecting portion; 624 : outer periphery of cam portion; 625 : pitch circle; 626 : bottom face of cam portion; 627 : stepped hole; 628 : flat surface; 629 : inclined face; 631 , 632 : end of coil spring; 641 , 1641 : case body; 642 : flange portion; 651 : outer periphery of cover; 652 : threaded portion; 653 : through-hole; 654 : surface of cover; 655 : rear surface of cover; 656 : hexagon socket; 657 : seating face for rotating cam; 6410 A, 6410 B: end face of case body; 6411 : recessed portion for welding; 6412 : outer periphery of case body; 6413 : through-hole; 6414 : opening of case body; 6415 : bottom face of case body; 6416 : threaded portion; 6417 : spring guide portion; 6418 : inner periphery of case body; 6419 : groove; 6421 : bolt insertion hole; 6271 : spring guide hole; 163 : combination spring: 163 A: first coil spring; 163 B: second coil spring; 16415 : bottom of case body; 16417 : groove; 16417 A, 16417 B: inner wall of groove; and 16417 C: groove bottom.

4y

This is a continuation of application Ser. No. 782,811, filed Mar. 30, 1977, now U.S. Pat. No. 4,089,142. BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates to solar heated building structures such as dwellings and the like, and more particularly, to such building structures wherein a concrete slab forms a portion of the building structure foundation and functions as a heat sink. 2. Description of the Prior Art Building structures such as dwellings have been constructed on concrete slabs forming a major element of the building foundation. It has been determined that the concrete slab may act as a thermal storage device or heat or cold sink due to its affinity to store heat or cold for relatively long periods of time. Such concrete slabs have been formed to carry internal piping or conduits for the circulation of a liquid which is employed in the pick up of thermal energy by radiation upon a collector or heat exchanger mounted to the roof and facing the sun, whereby, during daylight hours thermal energy may be picked up by the collector and transferred to the slab, while during the night, the circulation of liquid within the piping embedded within the concrete may be employed in lowering the temperature of the rooms within the solar heated dwelling by transmitting thermal energy to the collector on the roof for dissipation to the now cooler external air. Such a solar heated dwelling is the subject matter of U.S. Pat. No. 4,000,851 issuing Jan. 4, 1977, to Volkmar Heilemann. In addition to storing heat within the concrete slab, a layer of rocks may be interposed beneath the concrete slab and in direct contact with the slab such that the rocks themselves act as a thermal storage mass and form part of the thermal heat sink. Such solar heated dwellings are costly due to the expense of piping and circulation of the liquid between the heat exchangers constituting solar collectors on the roof and the concrete slab and mass of rocks acting as a heat sink for the concrete slab building structure. Further, such concrete slabs tend to transmit heat directly to the ground above the frost line resulting in a great loss of heat during winter operation and a reduction in efficiency of the system. Further, the bottom of the heat sink assembly, as constituted by the upper concrete slab and the lower mass of rocks, is normally completely thermally insulated from the ground, and while this prevents loss of heat from the heat sink to the ground, it fails to make use of a natural source of low temperature thermal energy. SUMMARY OF THE INVENTION The present invention constitutes an improvement in a concrete slab building structure which includes a concrete slab forming the building structure foundation which supports the building enclosure mounted thereon and is interposed between the building enclosure and the ground. The improvement resides in means for thermally insulating the periphery of the slab from the ground, downwardly from the surface of the ground to at least the extent of the ground frost line and the placement of a series of edge abutting parallel rows of end-to-end abutting hollow cinder or concrete blocks, in axial alignment underlying the concrete slab and axially aligned in heat transfer therewith and with the ground below the frost line. The hollow blocks form a series of parallel transverse air circulation paths and means are provided for communicating these air flow paths within said blocks to the interior of said building enclosure such that thermal radiation entering the building structure interior and impinging upon the building interior causes heat to be circulated by air flow through said parallel air flow paths within the cinder blocks and within the interior of said building above said slab with said concrete slab and cinder blocks acting as a heat sink. Preferably, a layer of gravel extends between the concrete block layer and the ground to a level below the frost line to further act as a heat sink in conjunction with concrete blocks and said slab. A vapor barrier may underlie the concrete blocks and overlie the gravel. The building structure may further include vertical foundation walls mounted on a footing and extended within the ground to a distance below the frost line and surrounding the concrete slab, the array of concrete blocks, and the layer of gravel. Urethane thermal insulation sheet material extends vertically along the sides of the foundation walls facing the gravel and comprise said insulation means for insulating the periphery of the concrete slab from the ground. The building structure may comprise vertical walls extending upwardly from the foundation and being spaced therefrom and from the concrete slab by wooden sills which constitute, at least in part the thermal insulation means for the periphery of the concrete slab. To facilitate solar heating of the concrete slab, the vertical walls of the building structure on the sides facing the sun may be provided with glass windows to permit direct impingement of the sun on the upper surface of the concrete slab and building structure interior to thermally heat air flowing within the building structure by convection, and thermal insulation shutters may be provided for selectively blocking off thermal radiation to and from the building through said windows. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a sectional elevation of a concrete slab building structure employing the solar heating system of the present invention. FIG. 2 is a vertical section of a portion of the building structure taken along about lines 2--2 of FIG. 1. FIG. 3 is a horizontal sectional view of the building structure of FIGS. 1 and 2, partially broken away, to illustrate the duct work employed in the solar heating system of the present invention. FIG. 4 is a block diagram schematic view of a hot air assisted solar heating system for use in the building structure of FIGS. 1-3. DESCRIPTION OF THE PREFERRED EMBODIMENT Referring to the drawings, there is shown a building structure such as a family dwelling, indicated generally at 10, and being of two stories, the building structure being erected upon footings 12 which in turn support vertical foundation walls 14 about all four sides of the building. These footings and foundation walls are mounted within an excavation E or rectangular hole within ground G determined by the horizontal dimensions of the building structure, the excavation penetrating to a certain vertical depth within the ground. Of importance to the present invention, is the fact that the excavation E extends to a level somewhat below the normal frost line L of the ground. That is, particularly in the northern sections of the country during the winter, the ground freezes progressively and to a distance vertically downward from the ground surface as determined by the length and severity of the freezing temperatures to which the ground is subjected. Nevertheless, below the frost line L, the ground maintains itself at a temperature of 40° to 50° F. and therefore acts as a winter heat sink or summer cool sink which is very pertinent to the present invention. The building is shown in somewhat simplified form, particularly to stress the inventive concept which constitutes a solar heated system of simple construction and one which completely eliminates the necessity for liquid heat collectors and the piping necessary to feed or circulate liquid through a heat exchanger or collector mounted to the roof as is exemplified by the referred to patent. Specifically, and important to the present invention, a concrete slab 16, which in the building structure 10 as shown is rectangular in form, extends between the foundation walls 14. The peripheral edge 17 of the concrete slab 16 is extended by wooden sills 34 upon which the vertical walls 18 of the building structure 10 are mounted, the wood sills constituting thermal insulation members and preventing good thermal conduction between the concrete slab 16, vertical walls 18, and the foundation walls 14 which are in direct contact with the ground G at the walls of excavation E. Embedded within the concrete slab 16, which may be, for instance, 7 inches in thickness, is 6×6×10/10 wire mesh for reinforcing purposes. The concrete slab 16 therefore thermally floats relative to foundation walls. Further, the building structure 10 which rests upon the foundation as partially defined by foundation walls 14, footings 12 and the concrete slab 16, is composed, in addition to vertical walls 18, of a roof 24 and horizontal floors at 20 and 22 defining a first floor 28, a second floor 30, and an attic 31 for the structure. Since the building structure is to be heated at least partially by solar energy, east, west and south walls including the right side vertical wall 18, FIG. 1, are provided with glass windows as at 26 for both first and second floors which permit direct radiation of the structure interior including the concrete slab 16 through the windows 26, whereby the heat is picked up by air circulated due to thermo-siphon effect as shown in FIG. 1 or alternatively by forced circulation through the utilization of one or more blowers which may be associated with a horizontal center duct 32 beneath slab 16. Important to the present invention is the utilization of a series of parallel rows of end-to-end abutting and axially aligned and side-to-side abutting cinder or concrete blocks indicated generally at 38 forming a cinder block array 56. The blocks 38 are hollow and formed with paired parallel passages or holes at at 38a. A single hole may extend through the blocks 38. The sides 38b of the blocks of adjacent rows abut each other while the ends 38c of respective blocks 38 within a given row abut each other and are in axial alignment, as may be seen by reference to FIGS. 1 and 2. Thus, the holes 38a of the blocks form elongated transverse air flow paths which extend from longitudinal or lengthwise passages 52 and 54 at opposite lateral ends of the cinder block array. The cinder block array indicated generally at 56 forms in conjunction with the concrete slab 16 the basic heat sink for the solar heating system of the present invention. Preferably, the blocks 38 are positioned on top of a mass of gravel 40 which fills most of the excavation space between the foundation walls 14, the gravel being applied over a one inch styrofoam sheet material layer 44 which abuts the ground G below the frost line L such to permit thermal conduction between the gravel and the ground G over a full horizontal surface area corresponding to that of the concrete slab 16. The gravel acts in addition to slab 16 and cinder block array 56 to store some of the heat and permits heat by conduction to pass to and from the cinder block array 56 and the concrete slab 16 to the ground G. Interposed between the bottom of the cinder block array 56 and the gravel 40 is a vapor barrier 42 which may take the form of four mill polyethylene sheet material. In order to prevent heat transfer to that portion of the ground above the frost line L, about the periphery of the gravel 40, the cinder block array 56, and at least a portion of the concrete slab 16, there is provided a thermal insulation barrier in the form of paired thermal insulation sheets, constituted by an outer sheet 49 in direct contact with the side of the foundation walls 14 facing the gravel, and constituting preferably 2 inch urethane sheet material, while the interior layer or sheet 50 may comprise a continuation of the one inch styrofoam sheet material layer 44 lying between the gravel 40 and the ground G. If desired, one or more of the longitudinal passages 52 and 54 may carry a sheet metal duct or member such as 58 which extends the complete length of the building and which is provided at intermediate locations with lateral duct openings as at 60. In this case, both the bottom and the outside vertical walls of the sheet metal longitudinal duct member 58 is suitably covered with fiberglass thermal insulation to minimize radiation heat losses therefrom. The cinder or concrete blocks 38 may comprise 12 inch standard weight concrete blocks having, as noted previously, two parallel holes 38a defining the horizontal transverse air paths for the multiple row cinder block array. Further, it is preferred that the blocks 38 be loosely placed but in end-to-end and axially aligned abutment and in side-to-side contact with other blocks of adjacent rows so as to define multiple rows which extend from the front to the rear of the building, FIG. 1. The cinder blocks 38 form parallel heat transfer air flow paths between the laterally spaced longitudinally extending ducts 52 and 54. Even when the temperature outside of the building is 0° F., the ground G immediately beneath the sheet materials 44 and underlying the gravel 40 is from 40° to 50° F. This ground, therefore, acts as a heat source relative to the building structure interior, and regardless of any applied thermal energy input to the building interior above the concrete slab 16, there would be sufficient heat transfer by conduction to the cinder block array 56 from the ground G below the frost line L for pick up by the air circulating by thermal siphon effect through the first and second stories 30 and 28. This is sufficient to maintain the interior of the building at approximately 40° F. or above freezing, and if the building were used as a vacation home or the like and unheated during the winter, this would be sufficient under most conditions to prevent freezing of the water pipes within the structure 10 regardless of lack of applied heat by a furnace, electric heater or other thermal energy input. However, due to the solar energy passage by way of the rays R through the windows 26, the slab tends to heat up as well as the interior walls of the building and floor, causing heat to be transmitted to the air circulating as indicated by the arrows A within these rooms and passing into and out of longitudinal passages 52 and 54 via the vertical slots 36 and 37, respectively, adjacent the periphery of the concrete slab and being transferred laterally through the horizontal air flow paths as defined by the aligned openings 38a within the various cinder blocks 38. Further, some of the heat is transmitted by conduction through the walls 18, for instance, and picked up by convection of the air moving across those surfaces. The rooms 28 and 30 form natural mixing chambers; for instance, if there were a stove within the first floor, this would radiate heat to the interior of the first floor 28 where that heat would be picked up by the air circulating, arrows A, within that floor, and mixing with the air from the upper floor 30 and moving into the longitudinal passage 52 for transfer laterally through the cinder blocks. Preferably, the concrete slab is poured with the cinder blocks in place such that the concrete flows into intimate contact between and about the concrete blocks to in fact bury the blocks in situ, and in hardening to form a composite, basic two layer heat sink, that is, the upper layer constituting the concrete slab and the lower layer constituting the cinder block array. As shown in FIG. 1, the wall containing the glass windows 26 is provided on the interior with thermal insulation shutters 64 which are shown as raised but which may be lowered as indicated by the double headed arrows 70 to overlie the glass 26 completely and to impede heat flow into and out of the building by both conduction and radiation. At night, therefore, the thermal insulation shutters 64 would be pulled and moved across the glass window to prevent heat loss from the building interior (except by natural conduction) through the walls and insulation shielded glass layer. Thus, the air circulating through the house and drawn through the passages defined by the openings 38a within the individual cinder blocks act in the summer to cool the house during the day and heat it in the winter. Heat transfer is particularly enhanced by the fact that the interior of the holes 38a of the cinder blocks are very rough and provide good heat transfer with the air which is prevented from laminar flow due to the roughness of the interior surfaces of these blocks. It is estimated that a dwelling constructed in the manner of the present invention and functioning during the months of January and February of 1977 in employing the solar heating system of the present invention, provides approximately 40% of the heat load of the building, thereby effectively reducing the heat costs of the building by approximately a 40% factor during these months. Where the buildings are employed as family dwellings and the temperature is maintained from 65° F. to 70° F. within the building interior, there is some loss of heat through the gravel and insulation layer 44 to the ground, but this loss is relatively low since the Δt is low. Obviously, the heat loss of the building above the slab is controlled by the thermal insulation for the external walls, the roof structure and/or the ceiling between the upper story and the attic. However, the novel solar heating system of the present invention is characterized by the utilization of south facing windows as at 26 which are about 80% efficient in contrast to the best liquid roof collector which is between 40% and 60% efficient. Thus, the present invention needs only about one-half the glass area to collect the same amount of solar energy as compared to a roof mounted collection system. Further, the heat is radiated directly to the concrete slab which acts as a heat sink and the excess heat is readily stored within the first floor concrete slab. The stored heat subsequently assists in heating the home at night and on cold days by radiation from the slab, the cinder block array 56 and the gravel 40. The presence of the vertical air passages 33, 36,37 in the various floors permit the heat derived from a wood buring stove in the family room to be either distributed to other parts of the dwelling or to be placed in storage via the passages 38a within the cinder blocks. At any point where direct sunlight enters through windows, the sun radiates and heats the building interior, i.e., the concrete, the surrounding walls or upper floors even through layers of linoleum, rugs, etc. There is natural transfer of heat therefore by conduction and convection. Thermal siphon effect of mechanical blowers for positive circulation of the air, is such that the temperature of the air captured within the internal volume of the dwelling tends to become the termperature of the slab. The house acts as a mixing chamber so that any central or localized heat causes the temperature at the slab to pick up some of the heat. By reference to FIG. 1, it may be seen that the transverse rows of concrete or cinder blocks 38 are interrupted at approximately the center of the building to form a third longitudinally extending air passage 35 which parallels passages 52 and 54. Within this passage 35 is mounted the sheet metal cold air return duct 32, being provided with a series of lateral openings as at 32a which permit selectively air flow to be achieved by way of a mechanical blower associated with the cold air return duct 32 as at B within L portion 32b, thereby pulling air, FIG. 1, from the left and the right to the center longitudinal passage 35 in contrast to the circulation of the air as shown in FIG. 1, wherein the air enters passage 52, passes by the duct holes from left to right and exits back to the building interior through vertical openings 36. In the absence of blower operation, thermal siphonic air circulation occurs as in FIG. 1, this being achieved by the warm south wall and cold north wall setting up convection currents. When the air circulation is required, for instance, at night when the house temperature is less than 72° F., forced air circulation occurs by energizing blower B and causing air to flow down along both walls and to the center of the cinder block array from left and right and for discharge into the building interior rooms through the cold air duct return openings within respective rooms (not shown). A typical operation involving the passive, thermal siphonic air circulation solar heating system of the present invention in conjunction with a furnace. In that regard, reference to FIG. 4 shows diagrammatically the operation of such system in which the building structure enclosure identified as the house is connected via duct work D to the solar slab duct work indicated by schematic lines to the solar slab 16, there being a thermostat 3, operable at 68° F. within the duct work, as at 76, a thermostat 4 operable at 80° F. within the duct work, as at 78, the furnace blower B, a furnace F and a damper which selectively vents the air circulating with the duct work D to the outside, via vent extension 82, although normally it circulates the air flow through the house. Within the schematic diagram of FIG. 4, thermostat 1 may be located on the second floor 30 of the building structure having a day setting of 68° F. such that the contacts close below 68° F., thermostat 2 for instance could be located on the first floor and set for 75° F., such that the contacts close below 75° F. Thermostat 3 is located in the fan duct upstream of the blower B, set for 68° F., that is, its contacts close below 68° F., while thermostat 4 is also located in the fan duct and set at 80° F. with its contacts closing below 80° F. In a typical installation, therefore, with the employment of such thermostats, a typical winter operation would be one in which thermo-siphon effect may be employed for circulation of air, particularly with adequate thermal input by radiation through the windows 26 of the building. Forced air circulation would occur with the furnace blower motor operating when the temperature within the downstairs or first floor room 28 drops below 75° or the air temperature within the second floor drops below 68°. Further, if the air temperature in the furnace blower drops below 68°, the furnace gun and the blower are operating so that the furnace adds heat to the powered forced air being circulated through the system. If the air temperature into the furnace blower is greater than 68° F., the furnace gun does not go on, and the warm air is circulated from the solar slab 16 which is sufficient to maintain proper temperature within the rooms of the building structure 10. In contrast, during summer and under the cooling mode, the operator manually closes a switch for instance on a time clock to allow the blower B to operate from 12 o'clock midnight to 4:00 A. M. continuously. During this time, the motorized damper 80 exhausts warm air to the outside through the vent duct 82. Upon building structure overheat, the thermostat 2 will effect circulation of cool air from the solar slab should the house overheat during the day, with the vent damper 80 closed in the sense that air is continuously circulated through the house and duct work and is not vented to the outside by way of the vent duct 82 which is closed off to the main duct work D. Thermostat 4 is an override shut off control for summer cooling. In summer time when the air temperature coming out of the solar slab exceeds the setting on thermostat 4, i.e., 80° F., this calls for an override for system shut down. In other words, the capacity of the solar slab to absorb heat has been exceeded, so that 80° F. would tend to make the house uncomfortable. The blower now shuts off. That is the point at which a mechanical air conditioner (not shown) would have to operate, or if there is no mechanical air conditioner, the house windows would have to be opened and the house vented, because the primary heat sink has absorbed all the heat it is capable of doing within its capacity. In its most simple sense, it is evident that the solar heating system of the present invention as applied to a slab constructed house permits the house to be continuously in thermal balance, that is, if the solar slab 16 is at a temperature too high with respect to the building interior, heat will be given off and circulated through that building. Further, the solar slab will lose some heat continuously due to the temperature differential which exists between the slab and the ground G and across the concrete block array 56. Should the air be warmer than the solar slab, obviously heat is given up during air circulation. Further, the existence of the thermal insulation shutters permits the heat loss or heat input through the windows to be readily varied to meet changing conditions. Purposely, the storage capacity of the heat sink, that is, the mass of concrete and gravel and cinder blocks must be balanced to the heat gain and heat loss of the building, the heat gain being principally on the south side through the windows and the heat loss by way of radiation throughout the building and some minor radiation through the gravel 40. The solar heating system of the present invention has the natural ability to store at low purchased energy cost hundreds of thousands of BTU per day in excess of the normal house needs for the period of solar energy collection, which BTUs are stored within the heat sink compositively formed of the solar slab, the cinder blocks and the gravel. The stored BTUs are then available for heating the house in the winter during the night and ensuing cloudy days and in the summer for expulsion at night. Of course, the storage capacity may be readily varied as may the heat gain and heat loss characteristics of the building so as to ensure proper balance dpeending upon the geographical location of the building and exposure to the solar radiation. The present invention advantageously employs these factors in the creation of a simplified, preferably passive solar energy heating and cooling system. While the invention has been particularly shown and described with reference to a preferred embodiment thereof, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention.

4y

This is a divisional application of application Ser. No. 07/994,917, filed Dec. 22, 1992, now U.S. Pat. No. 5,369,884. FIELD OF INVENTION The present invention relates to mill rolls, and the method of manufacture therefor, for the grinding of a fluid containing-material and the extraction of fluid therefrom. More particularly, this invention relates to perforated mill rolls for the grinding of sugar cane and the extraction of sucrose juice therefrom. BACKGROUND OF THE INVENTION Sugar making is one of the oldest industries in human history. One of the most important steps in the sugar making process is cane milling, which involves the grinding of sugar cane under pressure between counter-rotating rollers to extract the sucrose juice. A concise review of the cane milling technology is described in Cane Sugar Handbook, James C. P. Chen, 11th ed., John Wiley & Sons (1984). The materials contained therein are incorporated herein by reference. As taught by Cane Sugar Handbook, the most common milling units generally comprise three cylindrical mill rollers arranged in triangular form, although milling units with two to five or more rollers are also used. Usually three to seven sets of such mill units are used to form a milling tandem. A mill roller typically comprises a cylindrical roll body tightly shrink-fitted upon a central shaft. In general, most mill roll bodies have V-shaped circumferential grooving on the periphery to increase the grinding area per unit length. The size of the grooving generally decreases from the first mill roller to the last mill roller and can range from four to six grooves to the inch to one inch per pitch or larger. Typically a three roller unit comprises a "top roller" (or "top roll") and two "bottom rollers" (or "bottom rolls") arranged in a triangular relationship. The two bottom rollers comprise a "feed roll" or "cane roll" at the upstream end for receiving the shredded cane, and a "discharge roll" or "bagasse roll" at the downstream end for exiting the crushed bagasse. During the milling process the prepared cane is first fed into the opening between the top and the feed rolls. Then the bagasse, along with some expressed juice, is guided from the opening between the top and the feed rolls to that between the top and the discharge rolls over a curved plate positioned between the feed and discharge rolls below the top roller, frequently called a turn plate. The expressed juice is collected in a juice tray underneath the bottom rollers. Due to continuous corrosion by the acidic sucrose juice and the heavy abrasion by the tremendous tonnage of cane that is processed under great pressure each day, all roll bodies inevitably experience noticeable wear as the cane harvesting season progresses. A reduction of the external dimensions by over an inch in one season is not uncommon. The performance of a mill is often measured by three indications: (1) crushing or milling capacity, (2) sucrose extraction, and (3) bagasse moisture level; all except the bagasse moisture should be as high as possible. Unfortunately, one of the inherent operational difficulties experienced with the conventional rollers is the inadequate drainage of the expressed juice, a problem compounded by the common practice of adding water or thin juice to the bagasse to enhance the extraction, a process called "imbibition". Inadequate drainage can cause flooding at the entrance of the mill with the expressed juice sometimes flowing over the top of the top roller. It can lead to choking of the mill which seriously reduces the mill's crushing capacity. Inadequate drainage also aggravates the re-absorption problem, a phenomenon occurring when trapped juice near the top roll has to percolate its way through the cane blanket to the juice tray and when expressed juice at the pinch gets carried along by the expanding bagasse blanket extruding from the pinch opening. All such problems are detrimental to the performance of a mill. Some of the drainage problems are ameliorated by using the so-called Messchaert juice grooves, which are essentially radial extensions of the bottoms of the V-grooves formed on the bottom rolls, especially on the feed rolls. The purpose of the Messchaert juice grooves is to provide outlets for the downward draining of the expressed juice. They are therefore of little or no benefit to the top rolls. To further improve the drainage efficiency of a mill, a series of perforated rolls has been developed. U.S. Pat. No. 3,969,802 (hereinafter, "the '802 patent") discloses a perforated top roll which comprises a steel body with a plurality of peripheral grooves. A plurality of axially extending juice channels are provided within the roll body. Juice passages connecting the outer periphery and the juice channels are formed by first machining out a plurality of female threaded holes on the roll body surface. Then a plurality of male threaded plugs, or inserts, each containing a round radial perforation, are screwed into the female threaded holes. With continuous rotation of the roller and corrosion by the acidic sucrose juice, the threaded connection can become loose and eventually these inserts or plugs may fall out of the roll body, causing serious processing difficulties and equipment damage. U.S. Pat. No. 4,391,026 ("the '026 patent") was intended to be an improvement over the '802 patent. It discloses a mill roll which similarly includes a roll body, a plurality of peripheral grooves, and a plurality of channels extending axially through the roll body at positions inwardly of the grooves. Perforations between the grooves and the channels are provided by forming within the roll body at the radial bottoms of the grooves a plurality of radial recesses and fitting within such recesses a plurality of inserts, each of such inserts containing a radially extending perforation. These inserts are then welded into the recesses. Such welds are often degraded by the acidity of the sucrose juice and the heavy abrasion and wearing of the roll surface, leading to the same insert fall-off problems and the related maintenance inconvenience. U.S. Pat. No. 4,561,156 ("the '156 patent") discloses a roller comprising a plurality of roller shell segments, each roller shell segment having a plurality of peripheral grooves and ridges on the outer side and a longitudinal key on the inner side to fit a mounting sleeve. Juice collecting ports are provided within the roller shell segment to provide communication between the outer periphery and internal channels formed between the roller shell segments and the mounting sleeve. The mill roller of the '156 patent contains inserts that are quite different from those stated above; the entire roller shell segments are inserted onto the mounting sleeve by cap screws or other threading means. The entire insert segments can fall off from the roll body and cause more severe problems. U.S. Pat. No. 4,765,550 ("the '550 patent") discloses a juice extracting mill roll provided with a plurality of juice channels connected with a plurality of juice inlet passages which extend to the periphery of the mill roller. The '550 patent distinguishes from the '802 and '026 patents in that the juice inlet passages have a longer dimension in an axial direction and a shorter dimension in a circumferential direction. The main object of the '550 patent is to reduce the risk of clogging of the juice inlet passages by bagasse and of the flow back of expressed juice from the juice channels to the periphery. Other perforated mill rolls are disclosed, for example, in U.S. Pat. Nos. 4,546,698 and 4,989,305 and Australian Patent No. 556,846, all of which involving inserts that are fitted into recesses in the roll body from its outer periphery. These inserts are needed in order to provide radially inwardly diverging juice passages between the periphery of the roll body and the axial juice channels designed to facilitate flushing of trapped bagasse. However, none of these prior art patents addresses the issue of fall-off problems associated with such inserts. Because the inserts are fitted radially inward from the outer periphery of the roll body, the dimensions of the recesses are such that their cross-sectional areas cannot increase in the radially inward direction, and no structural means is available to keep the inserts in the recess. Welding means provides a stronger securing force than threading means for holding the inserts in the mill roll. However, welds can be degraded by the corrosion of the acidic sucrose juice and externally applied welds are always at risk of being completely removed by the abrasion and wearing of the roll surface. Moreover, because cast iron objects are not as easily and readily weldable into other objects as steel, both the inserts and the roll body often have to be made of cast steel, even though it is well known in the art that cast steel has inferior resistance to corrosion and abrasion compared to cast iron. SUMMARY OF THE INVENTION The primary object of the current invention is to provide an insertless perforated mill roll which contains cast-in radial perforations, thereby eliminating the mechanical and chemical problems experienced in the prior art perforated mill rolls while preserving and enhancing all their advantages, such as increasing a mill's crushing capacity and fluid extraction and decreasing the fluid content in the crushed material. More particularly, the primary object of the current invention is to provide an insertless perforated mill roll which eliminates the insert loosening and fall-off problems which are the major drawbacks of the prior art perforated mill rolls. Another object of the current invention is to provide an insertless perforated mill roll body which does not involve externally applied means such as welding, threading or force-fitting from the outer periphery of the roll body to effectuate the radial perforations. Yet another object of the present invention is to provide an insertless perforated mill roll which can improve drainage of the expressed fluid, minimize reabsorption, and eliminate the problems of flooding, choking and slipping experienced with conventional mill rollers without significantly increasing the operating cost and/or maintenance requirements. Yet a further object of the present invention is to develop a method for manufacturing insertless perforated mill roll bodies that allows wide flexibility in design as well as selection of construction materials. For clarity, a "mill" means a complete milling unit, which typically consists of three rollers, as described hereinabove. A "mill roller" comprises a roll body or shell sleeved upon a roller shaft. However, it is to be understood that the terms mill roll, mill roller, roller shell and roll body are frequently used interchangeably in the prior art publications. For a perforated mill roll, the generally radially extending fluid "perforations" or "passages" and the generally axially extending hollow fluid "channels" are formed within the roll body. These void spaces are the most essential elements of a perforated roll relative to a conventional non-perforated roll. All the prior art perforated mill roll bodies always start with the construction of a conventional, i.e., non-perforated, roll body. Thereafter, surface perforations are obtained by machining off or drilling out a portion of the surface of the roller to form a plurality of recesses which can accept inserts containing such perforated passages. The inserts are subsequently affixed to the roll body by either threading, welding, press-fitting, force-fitting, shrink-fitting, or other externally applied means. In the present invention, on the contrary, the manufacturing of the perforated roll body begins with the construction of a plurality of shish-ke-bab-like fluid channel strings. In a preferred embodiment, each fluid channel string comprises a fluid channel wall member having a plurality of fluid passage members fixedly attached thereon. The final roll body is then formed by casting a castable material around the plurality of shish-ke-bab-like fluid channel strings arranged generally circumferentially inside a mold. In the preferred embodiment, the fluid channel wall members are hollow elongated bodies with a plurality of apertures formed at selected positions corresponding substantially to the surface perforations in the final perforated roll body. They can be conveniently constructed from commercially available iron, steel, stainless steel, fiberglass or plastic tubes or pipes. However, they can also be fabricated or assembled from plate materials, from castings, extrusions, or from materials produced by other suitable means or combination thereof, to attain any desired configuration or cross-sectional shape. The fluid passage member is a three-dimensional object containing at least one fluid perforation. Typically, it is defined by a top surface, a bottom surface, and side surfaces therebetween, the top surface being the surface closest to the periphery of the roll body in the completed construction. It is preferable that the fluid passage member be formed to have a generally greater cross-sectional area towards the bottom and a narrower or smaller cross-sectional area towards the top. This geometrical configuration effectively turns the fluid passage member into an anchoring structure inside the roll body. While the bonding developed during the casting process should hold the fluid passage member firmly within the roll body, the anchoring structure simply provides the additional assurance that the fluid passage member will never fall off from the roll body during operation. Consequently, the life of the roller can be prolonged with little additional maintenance. It should be noted that such an anchoring structure can be obtained by any geometric shape or configuration that allows at least a portion of the circumferential surface of the fluid passage member to be buried radially inwardly of the roll body casting. Such an anchoring support is particularly important when the fluid passage member is made of a different material than the roll body casting. The fluid perforations in the fluid passage members provide the eventual fluid passages between the outer periphery of the mill roll and the fluid channels, which are generally axially extending. As the fluid passages extend generally radially in the final mill roll, they are conveniently described as "radial fluid passages". Because the fluid passage members containing the radial fluid passages are constructed prior to the formation of the mill roll body, great convenience and flexibility are possible with respect to the design of the final product. The radial fluid passage can be formed either during the fabrication, assembly, or casting of the fluid passage member or subsequent thereto by drilling or any other suitable means. It can be an open hole penetrating the entire depth of a fluid passage member, extending from its top surface to its bottom surface. It can also be in the form of a recess initially, penetrating only through the bottom surface, with the top perforation subsequently obtained by machining off the top portion of the fluid passage member after the final mill roll body is constructed. To form the plurality of fluid channel strings, the fluid passage members are fixedly attached onto the fluid channel wall members in such a manner that each radial fluid passage is in communication with at least one fluid channel through a connecting aperture. Alternatively, each fluid channel string can be made by casting a castable material around a channel shaped core material made of epoxy resin, sand, clay or other suitable material with a plurality of fluid passage members or cores for the radial fluid passages attached or formed thereon. The core material can be removed after the casting is completed to provide the void spaces inside the fluid channel string. The final perforated roll body is formed by casting a castable material into a casting mold containing a centrally positioned cylindrical core and the fluid channel strings, the latter arranged in a generally circumferential manner inwardly of the periphery of the mold with the fluid passage members directing generally radially outwardly. It can be cast or molded from any castable material including cast iron, cast steel, other metallic, ceramic or even plastic materials. The final roll body from such a casting process contains void spaces constituting the axial fluid channels, the radial fluid passages, and a hollow central bore for receiving the roller shaft. If the fluid passage members already have perforations that run from the top surface to the bottom surface, little or no machining will be required on the fluid passage members to complete the perforations. Otherwise, a portion of the fluid passage member and/or the surface of the mill roll casting must be machined or ground off to expose the radial fluid passage, to provide thereby communications between the outer peripheral surface of the mill roll and the juice channels. To increase the grinding area per unit length of a mill roll, a plurality of circumferential grooves can be formed on the periphery of the roll body. Though not generally required, chevron grooves may also be formed on the flank surfaces of the circumferential grooves to improve feeding further. Such chevron grooves comprise a plurality of hook grooves, each composed of a forward or leading wall, a rear or trailing wall, and a trough, and are cut substantially perpendicular to the apex of the circumferential grooves. They can be arranged in a chevron shape with respect to the axis of the mill roll or generally axially along the roll surface at every one, two, or more circumferential grooves. All surface grooves can be formed by casting or more preferably by machining off a portion of the roll body surface. They may be formed as a part of the perforated mill roll body or after the roll is made, at the manufacturing shop or at mill site. One advantage of the present invention is that it allows a wide selection of materials from which the roll body may be constructed. Generally, it is preferable to have the fluid channel wall members made of steel because of the ready commercial availability of steel pipes. The fluid passage members and the remaining portion of the roll body including the grooves are preferably made of cast iron because of its relatively superior resistance to mechanical abrasion and chemical corrosion. The surface of the roll body may be roughened by arc welding to increase its ability to grab and feed the material to be crushed. This surface roughening is particularly desirable if cast steel is used to form at least the outermost surface of the roll body. In this disclosure, the word "radial" has a broad meaning which includes any direction from the axis of the roll to any point on its outer periphery, or vice versa. A radial direction can follow a non-straight, curved or tortuous path. Similarly, the word "axial" generally means any direction connecting any two points each selected from one of the two cylindrical ends of the roll body. An axial direction can also follow a non-straight, curved, tortuous, twisted, or spiral path. The perforated mill roll will be most effective if used as a top roll in the first mill of a milling tandem. However, it can also be used in subsequent mill units or as bottom rolls to improve the tandem's milling performance. One of the advantages of the cast-in insertless perforated mill roll of the present invention is that it can be readily employed as a substitute or routine replacement for any type of spent rollers. When a new roll body is needed, the insertless perforated roll body of this invention can be simply sleeved upon the existing shaft. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a revealed view of the perforated mill roll body of the present invention showing a plurality of circumferentially aligned fluid channel strings encased in the roll body. FIG. 2 is a perspective view of the shish-ke-bab-like fluid channel string. FIG. 3 is a perspective view of the fluid channel wall member having apertures formed thereon. FIG. 4 is a perspective view of the fluid passage member. FIGS. 5A and 5B show partial sectional views of two embodiments of the present invention. FIGS. 6A-6D show partial perspective views of four other embodiments of the present invention. FIGS. 7A and 7B show a radial and an axial cross-sectional view, respectively, of an embodiment showing a collar-extension-type affixing means for affixing a fluid passage member with a fluid channel wall member. FIGS. 8A and 8B show a radial and an axial cross-sectional view, respectively, of another embodiment showing a leg-extension-type affixing means for affixing a fluid passage member with a fluid channel wall member. FIGS. 9A and 9B show a radial and an axial cross-sectional view, respectively, of yet another embodiment showing a sleeving-type affixing means for affixing a fluid passage member with a fluid channel wall member. FIG. 10 shows a partial sectional view of yet another embodiment of the present invention containing an intermediary inner shell which is sandwiched between the roll body and the central shaft. FIG. 11 shows a partial sectional view of yet another embodiment of the present invention containing an inner shell within which the fluid channels are cast. FIG. 12 shows a partial sectional view of yet another embodiment of the present invention in which the fluid channels are defined by a plurality of grooves formed on the outer periphery of an inner shell and the inner periphery of an outer shell. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT Now referring to the drawings. In FIG. 1 it is illustrated a revealed view of the insertless perforated mill roll body 10 according to a preferred embodiment of the present invention. The mill roll body contains a plurality of shish-ke-bab-like fluid channel strings 20, each containing an axially elongated fluid channel 30, defined by a fluid channel wall member 32, and a plurality of fluid passage members 40. Each fluid passage member 40 contains therethrough a radial fluid passage 50. The roll body casting 60, which forms the rest of the roll body, is formed by casting a castable material around the shish-ke-bab-like fluid channel strings 20. The fluid passages 50 are therefore inherently cast in the roll body without the need of using externally applied inserts. A bonding force between the fluid passage members 40 and the roll body casting 60 is developed when the castable material solidifies. Such a bonding force is often adequate to fixedly secure the fluid passage members 40 within the roll body 10; however, other inherent means, which are described below, can be utilized to further secure the fluid passage members 40, or as an alternative securing means. Circumferential rings 11 are used to hold the fluid channel strings in place before and during the casting process. FIG. 1 also shows a hollow central bore 80 which is provided to allow the mill roll body to be sleeved upon a cylindrical roller shaft, not shown here, for ultimate installation as a mill roller in a cane milling unit. Circumferential grooves, which will be shown in subsequent figures, may be formed on the outer periphery 70 to increase grinding area per unit length of the roll body. FIG. 2 shows a perspective view of a preferred embodiment of the fluid channel string 20 of the present invention, while perspective views of the fluid channel wall member and fluid passage member are shown, respectively, in FIGS. 3 and 4. Each fluid channel wall member 32 has a plurality of apertures 21. These apertures are properly disposed so as to correspond substantially to locations of the perforations to be formed on the outer periphery of the final mill roll body 10. In FIG. 1, as well as in subsequent figures, the axial fluid channel 30 is illustrated to be defined by a fluid channel wall member 32. This is a preferred embodiment; however, fluid channels can be cast in the roll body using sand, resin, clay or other filler or core material. Since the fluid channels often have a large length/diameter ratio, if the latter option is desired, it may be preferred to use a stronger and non-decomposable core material such as a metallic core material with an anti-adhesion coating applied thereon to facilitate removal of the core upon completion of the casting. The shish-ke-bab-like fluid channel string can also be cast as a single unit. While each fluid channel wall member 32 is shown to have a uniform circular cross-section throughout the length of the channel, it can be of other different cross-sectional shapes, for example, elliptical, rectangular, trapezoidal, and/or truncated sector shaped. The trapezoidal or truncated sector shape is preferred if high flow rate is expected, each diverging towards the periphery of the roll body. Furthermore, it may be preferred that the cross-section of the fluid channel diverges from around its center to both ends. The fluid channel may also be angled or bowed from around its center point towards the outer periphery of the roll body (i.e., concave from the central axis) to improve the exit of extracted juice. It can further be curved, spiraled or twisted, if doing so should improve fluid flow therethrough. A long fluid channel wall member can be obtained by axially connecting a plurality of relatively shorter wall members together through threading, welding, sleeving or other coupling means. The fluid passage member 40 is a three dimensional object. In the preferred embodiment as shown in FIG. 4, it has a top surface 41, a bottom surface 42, and side surfaces 43 connecting the top surface and the bottom surface. In the final roll body, the top surface 41 is the radially outermost surface, and the bottom surface 42 is the radially innermost surface. It can be formed to have any shape such as cylindrical, truncated sector shaped, conical, pyramidal, spherical, or any combination thereof. The fluid passage members 40 are fixedly secured in the roll body by an adhesion force which generally develops during the casting process when the castable material is brought in contact with the outer surface of the fluid passage member 40 and solidifies. It is preferred that a portion of the fluid passage member 40 be provided with a greater cross-sectional area than its adjoining radially outer portion. By having a larger cross-sectional area at its radially inner or innermost portion, the fluid passage member 40 is provided with an anchoring means in the final mill roll body 10 after the casting is formed. The fluid passage member 40 can also be made of a wide variety of materials such as cast iron, cast steel, stainless steel, ceramic material, high strength plastics or any other suitable materials. Since cast iron is known to have better resistance to wearing and corrosion than cast steel, it is preferred that the fluid passage members be made of cast iron. The radial fluid passage 50 provides communication between the outer periphery 70 of the roll body and the axially extending fluid channel 30. Only one radial fluid passage 50 is shown in each fluid passage member in FIG. 4, but more may be provided therein. It can be furnished when the fluid passage member 40 is formed during the casting process using a decomposable core material. However, like the forming of the fluid channel, it can also be formed with a non-decomposable or reusable core such as a metallic core. It can also be formed by casting the fluid passage member around a fluid passage wall member, not shown, or in multiple stages to attain its required configuration. The purpose of using a multiple-stage casting process is to reduce the effect of thermal stress that may be exerted on the fluid passage wall member. Alternatively, the radial fluid passage can be provided after the fluid passage member is formed by drilling, milling, cutting, gouging, etching, punching or any other suitable means. It can also be formed by constructing and piecing together the fluid passage member in two or more segments. In the preferred embodiment as shown in FIG. 4, the radial fluid passage 50 is shown as an open channel. It may also be formed initially as a radial recess, with an opening through the bottom surface 42 of the fluid passage member 40 only. Surface perforations can be obtained and the radial fluid passage 50 exposed after the roll body 10 is formed by machining off a portion of the outer periphery 70 of the roll body and/or a portion of the fluid passage member 40. In the preferred embodiment shown in the figures, the radial fluid passage is shown to be an elongated rectangular passageway with a longer axial width and a shorter circumferential width. Such an orientation is preferred because the larger width in the axial direction increases radial fluid flux; whereas the smaller width in the circumferential direction, being the feeding direction of the material to be crushed, minimizes the risk of clogging. The radial fluid passage can also be formed as a similarly elongated passageway but with a longer width in the circumferential direction. Furthermore, the radial fluid passage can be made to have a round cross-section. It is also possible to have an assortment of radial fluid passages of various shapes and orientations formed in the same roll body. Since the fluid passage member of this invention can be formed by combining more than one segments, this greatly facilitates the process to make fluid passages of various shapes. To further minimize the clogging problem, the interior surface of the radial fluid passage can be sleeved, inlaid, or coated with a layer of low friction material such as teflon, chrome-plating or glass-lining. If the radial fluid passage includes a separate fluid passage wall member, it can likewise be made of low friction material such as teflon, glass, or polished stone. The fluid passage wall member can also be made from different materials with high resistance to corrosion and abrasion such as stainless steel. In the preferred embodiment as shown in FIG. 2, the fluid channel string 20 is formed by first forming the fluid channel wall member 32, then fixedly attaching the fluid passage members 40 containing radial fluid passages 50 onto the fluid channel wall member 32, the radial fluid passages 50 substantially matching the apertures 21 on the fluid channel wall member 32. In all the figures discussed heretofore, the fluid passage members are shown to have curved bottom surfaces substantially matching the curvature of the fluid channel wall member. However, such a curved bottom surface is not the only adoptable shape as the configuration of the seat for the fluid passage member on the fluid channel wall member may vary, at least in part according to the shape of the fluid channel wall member used. FIGS. 7A-B and 8A-B show two embodiments of the present invention which utilize an extension-recess affixing means to affix the fluid passage members to the fluid channel wall member. In FIGS. 7A and 7B, which show a radial and an axial cross-sectional view respectively of one of the embodiments, a collar extension 101 is provided as an extension of the bottom surface of the fluid passage member 40. The collar extension 101 defines a relatively shorter passage 103 extending from the fluid passage 50. A recess 102 of appropriate dimension is provided around the aperture of the fluid channel wall member 32. The recess 102 is so dimensioned that the collar extension can be tightly fitted therein with force. Welding means can be provided around the collar extension and the recess. In FIGS. 8A and 8B, which show a radial and an axial cross-sectional view respectively of another embodiment, the fluid passage member is shown to have two leg extensions 111 to be received by two matching grooves 112 provided in the fluid channel wall member 32 through a force-fitting means. These embodiments are preferred when the fluid passage member 40 is made of a material that has a higher thermal expansion coefficient than the fluid channel wall member 32, as disengagement thermally induced during the casting process can be effectively prevented by virtue of their structural configurations. Another embodiment is to provide a sleeving means in the form of two circular leg extensions from the fluid passage member 40, as shown in FIGS. 9A-B. The sleeving means 121 holds the fluid passage member 40 and the fluid channel wall member 32 in place by covering more than half of the circumference of the fluid channel wall member 32 after it is sleeved thereon. Again, welding means can be provided around the leg extensions and the fluid channel wall member. The FIGS. 9A-B embodiment is preferred when the fluid channel wall member 32 is made of a material that has a higher thermal expansion coefficient than the fluid passage member 40. The locations of the collar extension and its matching recess can be reversed on the fluid passage member and fluid channel wall member, and the sleeving means can be expanded to form a partial or complete ring-like damp to sleeve upon the fluid channel wall member and the fluid passage member. In addition to press-fitting, force-fitting, shrink-fitting, welding, or sleeving means, other affixing means involving threading, bolting, pinning, wedging, wrapping, gluing or a variety of third elements such as bolts, pins, keys, clips, clamps, rings, wires, or other coupling means can be used to hold the fluid passage member and the fluid channel wall member together. A combination of the various affixing means can also be used. To complete the construction of the insertless perforated mill roll body of the present invention, a castable material is cast around a plurality of the shish-ke-bab-like fluid channel strings 20 circumferentially disposed and supportively secured by a plurality of supporting rings 11 around a central core in a casting mold, as shown in FIG. 1. FIGS. 5A and 5B show partial sectional views of two embodiments of the insertless perforated mill roll body of the present invention so formed. The roll body 10 contains void spaces constituting the radial fluid passages 50 and the axial fluid channels 30 formed therewithin. A hollow central bore 80 (shown in FIG. 1) is provided to allow the roll body to be sleeved upon a cylindrical roller shaft 90. The roll body casting 60 comprises solid material. During fluid extraction, expressed fluid is forced from the outer periphery 70 of the roll body into the radial fluid passage 50 by a compressional force resulting from the grinding action of the mill rollers, and flows out of the axial ends of the roll body 10 through the axial fluid channels 30. To increase the grinding area per unit length of the roll body, circumferential grooves 91 are formed on the outer periphery 70 of the roll body. Each circumferential groove is defined by a groove bottom surface 92, flank surfaces 93, and a groove top surface 94. The circumferential grooves can be formed, preferably by removing a portion of the outer periphery, by machining, grinding, gouging or other suitable means, or by a casting process, or any combination thereof. Phantom lines 44 show the portion of the fluid passage member that has been machined off to form such surface grooves. The fluid passage members can be formed during the casting process to also contain portions of the circumferential grooves. The radial fluid passages can be formed to penetrate through one or more of the groove bottoms 92, one or more of the groove tops 94, or one or more of the flank surfaces 93, or any combination thereof. In FIG. 5A, the fluid passage penetrates one bottom surface, two complete flank surfaces, two top surfaces, and two partial flank surfaces. In FIG. 5B, the fluid passage penetrates one bottom surface and two partial flank surfaces. Other examples are illustrated in FIGS. 6A (one bottom surface), 6B(two partial flank surfaces but no bottom surface), 6C(one partial flank surface), and 6D(one bottom surface and one partial flank surface). One of the advantages of the present invention is the flexibility of design. An essentially infinite number and combination of configurations of the surface openings can be furnished to cater to desired applications. In the preferred embodiment, the openings are substantially aligned either circumferentially or axially. However, the openings can be staggered and/or slanted randomly or in any desired manner. Although the best mode contemplates the perforated roll body of the present invention to be sleeved upon a shaft, the present invention can be conveniently practised, when desirable, using various inner-and-outer shell configurations. FIG. 10 shows an embodiment of such configuration in which a solid inner shell 141 is sandwiched between the outer roll body casting 142 and the shaft 90. In another embodiment, which is shown in FIG. 11, the roll body casting comprises an inner shell 141 sleeved inside an outer shell 142. The fluid channels 30 are encased entirely in the inner shell 141, wherein radial perforations 143 are provided to allow communications with radial fluid passages 50 in the outer shell 142. The outer shell 142 can be formed by casting a castable material around a plurality of fluid passage members 40 using a procedure similar to that described above. Furthermore, as shown in FIG. 12, the perforated mill roll body can also be made to comprise two tightly sleeved cylindrical shells--an inner shell 141 and an outer shell 142. The fluid channels 30 are formed in part by surface grooves provided on the outer periphery of the inner shell 141 and in part by the inner periphery of the outer shell 142, with each of the radial fluid passages 50 so disposed to communicate with at least one of the aforementioned axial surface grooves when the shells are assembled. Void spaces comprising the fluid channels and the connecting radially extending fluid passages are thus formed inside the roll body when the outer shell is sleeved upon said inner shell. To complete the perforated mill roll body, each radial fluid passage can be made to be exposed at the outer periphery, if not already so, by removing a portion of the outer periphery of the outer shell or a portion of the fluid passage member or both by machining or other suitable means. The perforated mill rolls of the present invention are generally used as top rolls, which typically contain flanges 95 to keep the material being crushed within bounds and fluid guards 96 to protect the shaft from splashes of fluid draining off from the fluid channel openings at both ends of the roll body. However, as stated earlier, the perforated mill rolls of the present invention can also be used as bottom rolls. This invention discloses an insertless perforated mill roll body. Although the best mode contemplated for carrying out the present invention has been herein shown and described, it will be apparent that modification and variation may be made without departing from what is regarded to be the subject matter of the invention.

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RELATED PATENT APPLICATION This patent application is a divisional application of application Ser. No. 09/471,372, filed Dec. 23, 1999, for an invention titled “NON-LINEAR LIGHT-EMITTING LOAD CURRENT CONTROL”. BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a temperature-dependent current sensor circuit and a substantially constant intensity light source and corresponding method using this sensor circuit. 2. Brief Description of the Prior Art Insertion of an integrated power factor controller circuit such as controller MC33262 from MOTOROLA in an electric power supply system enables easy and efficient control of the power factor and the level of current harmonics. To obtain a power factor equal to unity, controller MC33262 draws current from the ac source in proportion to the sinusoidal voltage. This concept automatically causes the current waveform to be sinusoidal and in phase with the voltage waveform. Also, operation of power factor controller MC33262 requires that the output supply voltage be higher than the peak amplitude of the input sinusoidal voltage in order to draw current from the ac source throughout every cycle of the sinusoid. Accordingly, the output supply voltage must have an amplitude higher than the peak amplitude of the sinusoidal voltage of the ac source. In certain circumstances, an output supply voltage with an amplitude lower than the peak amplitude of the input ac voltage is required. In such cases, power factor controller MC33262 is used as a power-factor-correcting pre-converter; a second power converter is also required to reduce the level of the supply voltage to the desired amplitude. Necessarily, providing a second power converter involves additional costs and requires more space. Furthermore, the voltage/current characteristic of a light-emitting diode is sensitive to temperature causing the current through a light-emitting diode to change very rapidly and non-linearly with the voltage across the light-emitting diode. For example, for a given type of light-emitting diode widely used in the fabrication of traffic signal lights, a constant voltage of 1.8 volts will produce in the light-emitting diode a current of about 7.5 mA at a temperature of −25° C., a current of about 20.5 mA at a temperature of +25° C., and a current of about 30 mA at a temperature of +60° C. The magnitude of the current through the light-emitting diode at a temperature of +60° C. is therefore, for a constant voltage of 1.8 volt, about 1.6 times higher than the magnitude of the current at a temperature of +25° C. Voltage feedback control would therefore be very detrimental to the service life of such a light-emitting diode. Since voltage feedback control of the supply of a light-emitting diode is not desirable, current feedback control is required to ensure durability of the light-emitting diode. Also, a fixed LED output current presents the following drawbacks: at higher temperature the output LED power decrease; and at lower temperature the output LED power increases. OBJECTS OF THE INVENTION An object of the present invention is therefore to eliminate the above discussed drawbacks of the prior art. Another object of the present invention is to regulate the output power, hence the light intensity, of a non-linear light-emitting load. SUMMARY OF THE INVENTION More specifically, in accordance with the present invention, there is provided a sensor circuit for detecting a current supplied to a non-linear load and for producing a current reading dependent on a condition of operation of the non-linear load. The sensor circuit comprises first and second serially interconnected resistors also connected in series with the non-linear load, and a variable impedance connected in parallel with one of the first and second resistors, the impedance varying with the condition of operation of the non-linear load. At least a portion of the current through the non-linear load flows through the sensor circuit to enable the first and second serially interconnected resistors and the variable impedance to produce a variable voltage signal representative of the current through the non-linear load and dependent on the condition of operation. In a preferred embodiment of the invention, the non-linear load is a light-emitting diode (LED) or a plurality of LEDs, and the condition of operation of the LED is temperature. The invention described above therefore procures the advantage of providing a current-representative signal that may be used for feedback control of a non-linear load. Current feedback control is difficult with current sensor circuits which do not provide an output that varies with the condition of operation of the non-linear load. The invention described herein provides this feature in a simple low-cost circuit. The present invention also relates to a substantially constant intensity light source comprising: a) a non-linear light-emitting load; b) a controllable dc voltage and current source for supplying the non-linear light-emitting load with dc voltage and current; c) a current sensor circuit connected in series with the non-linear light-emitting load and the controllable dc voltage and current source, the current sensor circuit having an impedance varying with a condition of operation of the light-emitting load and being supplied with at least a portion of the current through the non-linear light-emitting load, whereby the variable impedance produces a variable current-representative signal; and d) a voltage and current control feedback circuit connected between the current sensor circuit and said controllable dc voltage and current source for controlling the dc voltage and current source in relation to the variable current-representative signal to thereby adjust the dc voltage and current to amplitudes that keep the light intensity produced by the light source substantially constant. Further in accordance with the present invention, there is provided a substantially constant intensity light source comprising: a) a controllable dc voltage and current source having first and second terminals; b) a non-linear light-emitting load connected between the first and second terminals and supplied with dc voltage and current from the controllable dc voltage and current source; c) a current sensor circuit connected in series with the non-linear light-emitting load between the first and second terminals, the current sensor circuit having an impedance varying with a condition of operation of the light-emitting load and being supplied with at least a portion of the current through the non-linear light-emitting load, whereby the variable impedance produces a variable current-representative signal, and d) a voltage and current control feedback circuit connected between the current sensor circuit and the controllable dc voltage and current source and through which the dc voltage and current source is controlled in relation to the variable current-representative signal to adjust the do voltage and current to amplitudes that keep the light intensity produced by the light source substantially constant. The present invention still further relates to a method for keeping the intensity of a light source substantially constant, comprising: a) supplying from a controllable dc voltage and current source a dc voltage and current to a non-linear light-emitting load: b) supplying at least a portion of the current through the non-linear light-emitting load to a current sensor circuit having an impedance varying with a condition of operation of the light-emitting load, whereby the variable impedance produces a variable current-representative signal, and c) feedback controlling the dc voltage and current in relation to the variable current-representative signal to adjust the dc voltage and current to amplitudes that keep the light intensity produced by the light source substantially constant. The objects, advantages and other features of the present invention will become more apparent upon reading of the following non-restrictive description of a preferred embodiment thereof, given by way of example only with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS In the appended drawings: FIG. 1 is a schematic block diagram of the electronic circuit of a light-emitting-diode lamp Incorporating the current sensor circuit and a power supply system according to the invention; FIG. 2 is a graph showing a LED current as a function of LED voltage at different temperatures without load current control; FIG. 3 is a graph showing LED output power as a function of temperature without load current control; FIG. 4 is a block diagram of the load current sensor circuit according to the invention; and FIG. 5 is a graph showing LED current, LED voltage, equivalent impedance and LED output power as a function of temperature with load current control according to the invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT Although the preferred embodiment of the present invention will be described hereinafter with reference to an application of the current sensor circuit according to the invention to a light-emitting-diode lamp, it should be understood that this example is not intended to limit the range of applications of the present invention. Referring to FIG. 1 of the appended drawings, the LED lamp is generally identified by the reference 1 . Lamp 1 comprises a set 2 of light-emitting diodes such as 3 . The set 2 is formed of a plurality of subsets such as 4 of serially Interconnected light-emitting diodes 3 . The subsets 4 of serially interconnected light-emitting diodes 3 are connected in parallel to form the set 2 . The cathode 7 of the last light-emitting diode 3 of each subset 4 is connected to a first terminal 9 of the current sensor circuit 10 . Current sensor circuit 10 has a terminal 11 connected to ground. The set 2 of light-emitting diodes 3 is supplied by an ac source 14 . The alternating voltage and current from the ac source 14 is rectified by a full-wave rectifier bridge 15 and supplied to the anode 16 of the first diode 3 of each subset 4 through a power converter 17 . To further smoothen the current waveform, an EMI (ElectroMagnetic Interference) filter and inrush current limiter 44 can be added between the ac source 14 and the full-wave rectifier bridge 15 . The current flowing through each subset 4 of light-emitting diodes 3 has a value limited by the impedance of current sensor circuit 10 . Also, the current flowing in all the subsets 4 of light-emitting diodes 3 flows through impedances 5 and 6 of the current sensor circuit 10 serially interconnected between the terminals 9 and 11 to convert the total current flowing through the set 2 of light-emitting diodes 3 to a corresponding current-representative voltage signal present on an output 18 of current sensor circuit 10 . In the illustrated example, the controller 19 is the power factor controller manufactured and commercialized by Motorola and identified by the reference MC33262. To enable the controller 19 to perform variable current feedback control on the set 2 of non-linear light-emitting diodes 3 , the current sensor circuit 10 is connected to the input 24 of the power factor controller 19 through the filter circuit 20 . The function of the current sensor circuit 10 is to transform the non-linear relation (LED current/voltage relation with temperature) between the LED supply dc voltage at the output 26 of the power converter 17 and the dc current supplied to the set 2 of light-emitting diodes 3 with temperature into a linear relation. Referring to FIG. 2, LED current (I LED ) measurements at various temperatures are shown with respect to LED voltage when no current sensor circuit according to the present invention is used. In FIG. 2, temperature θ 1 is smaller than temperature θ 2 , which is itself smaller than temperature θ 3 . Note that at a reference LED current (I LEDref ), LED voltage V F1 is greater than LED voltage V F2 , which is itself greater than LED voltage V F3 . At a fixed current (I LEDref ), the output power (P LED ) as a function of temperature θ is given in FIG. 3 . The output LED power P LED is defined by:  P LED =V F ×I LEDref . FIG. 3 shows that, without the current sensor circuit of this invention, at a lower temperature (θ 1 ), the LED output power P LED1 is higher and, at the higher temperature (θ 3 ), the LED output power P LED3 is lower That is: P LED1 >P LED2 >P LED3 . In order to avoid variations in the LED output power P LED with temperature θ at a fixed current, current sensor circuit 10 of FIG. 4 is introduced. As shown in FIG. 4, the current sensor circuit 10 comprises the temperature dependent variable equivalent impedance Z eq , which includes two impedances in series Z 6 and Z 6 . Z 5 comprises a fixed resistor R 12 , ( 12 ) in parallel with thermistor R TH ( 8 ). Both R 12 and R TH are in series with impedance Z 6 which can be implemented as a fixed resistor R 13 ( 13 ). The temperature dependent variable equivalent impedance Z eq is given by: Z eq  ( θ ) = Z 5 + Z 6 = R 12 * R TH  ( θ ) R 12 + R TH  ( θ ) + R 13 The current-representative voltage signal I mes is given by the product of LED current I LED ( 9 ) and a variable equivalent impedance Z eq (θ) ( 10 ); where Z eq is formed of passive elements and is a non-linear impedance dependent on the casing of the LED lamp, the power supply, the LEDs and surrounding temperature θ. I mes =Z eq (θ) *I LED The current-representative voltage signal I mes has an amplitude that is proportional to the magnitude of the current flowing through current sensor circuit 10 (Z eq ). This circuit enables regulation of the dc current supplied to the LEDs as a function of temperature θ. When the temperature θ is constant, the current sensor circuit 10 impedance value Z eq is constant and the LEDs are driven by a constant current. Referring to FIG. 5, when the temperature θ rises to the maximum temperature θ max , the value of the thermistor R TH decreases such that: Z 5 ≅R TH min The equivalent sensor impedance value Z eq (θ) diminishes until it reaches Z eqmin , where Z eq min ≅R TH min +R 13 and the maximum current on the LEDs is: I LED m     a     x ≃ I ref Z eq m     i     n ≃ I ref R TH m     i     n + R 13 where I ref is a voltage providing a fixed LED current reference. As a result I mes diminishes and the difference E between fixed reference current I ref ( 47 ) and filtered LEDs current measure I mes ( 24 ) increases, so that the LED current is increased by the power supply until the difference E=I ref −I mes equals zero. The maximum current on the LEDs is therefore limited by the choice of R 13 ( 13 ) of current sensor circuit ( 10 ). This in turn maintains a roughly constant power output from the LEDs. Conversely, if the temperature drops until the minimum temperature θmin, the value of resistor R TM increases such that: Z 5 ≅R 12 and the equivalent sensor impedance value Z eq (θ) rises until: Z eq max ≅R 12 +R 13 and the minimum current on the LEDs is: I LED m     i     n ≃ I ref Z eq m     a     x ≃ I ref R 12 + R 13 As a result I mes increases and the difference E decreases so that the power supply decreases the current in the LEDs until the difference E is again equal to zero. Hence, the upper limit for current to the LEDs is limited by R 13 , (i.e., R TH minimum at higher temperature), while the lower current limit is determined by (R 12 +R 13 ), (i.e., R TH maximum at lower temperature). As explained above this LED lamp output regulation is based on variation of current measurement with temperature as shown in FIG. 5 . Referring back to FIG. 1, the filter circuit 20 comprises a resistor 21 connected between output 18 of the current sensor circuit 10 and input 24 of the controller 19 , and a capacitor 25 connected between terminal 23 of the resistor 21 and the ground. The values of the resistor 21 and capacitor 25 also contribute to transform the non linear relation between the LED supply dc voltage at the output 26 of the power converter 17 and the dc current supplied to the set 2 of light-emitting diodes 3 into a linear relation. The values of the resistor 21 and capacitor 25 must therefore be precisely and carefully adjusted in relation to the current characteristic of the voltage/current characteristic of the type of diodes 3 being used. To current feedback control the supply of the set 2 of light-emitting diodes 3 , the controller 19 requires on its input 24 a current-representative voltage feedback signal which varies linearly with the LED supply dc voltage at the output 26 of the power converter 17 . The current-representative voltage feedback signal on input 24 will be compared to I ref ( 47 ) in comparator 48 . The output of comparator 48 is a high/low difference-representative signal fed to multiplier 49 . Multiplier 49 also has as an input a reference control voltage from output 52 of an input reference current sensor 51 . Multiplier 49 adjusts its gain according to its inputs and produces a corresponding current reference waveform signal 50 . The multiplier output 50 controls the inductor current sensor 35 threshold as the ac voltage traverses sinusoidally from zero to peak line voltage. This has the effect of forcing the MOSFET 33 “on time” to track the input line voltage, resulting in a fixed drive output “on time”, thus making the preconverter load ( 17 plus 4 ) appear to be resistive to the ac line. Controller 19 also receives on input 38 (zero current detector input) the current-representative voltage appearing across additional coil 37 (to be described later) through resistor 39 . Input 38 is compared with, in a preferred embodiment, a 1.6V reference 56 in comparator 55 . The output of comparator 55 is a high/low difference-representative signal 54 fed to multiplier latch 53 . The multiplier latch 53 also receives a voltage signal input 36 from the inductor current sensor 35 . The multiplier latch 53 ensures that a single pulse appears at the drive output during a given cycle. Multiplier latch 53 will therefore produce the high or low logic level drive output for controlling MOSFET transistor 33 an or off thereby effectively controlling output 28 of flyback power converter 17 . Still referring to FIG. 1, the power converter 17 comprises an inductor device 30 having a core 29 , and a coil 27 supplied with full-wave rectified voltage and current from the rectifier bridge 1 5 . A second multi-tap coil 28 is wound onto the core 29 of the inductor device 30 , The coils 27 and 28 act as primary and secondary windings, respectively, of a transformer. Rectified voltage and current applied to the coil 27 will induce in the coil 28 rectified voltage and current transmitted to a capacitor 31 through a diode 32 . Electrical energy is stored in the capacitor 31 to convert the full-wave rectified voltage and current induced in the coil 28 to dc voltage and current supplied to the output 26 of the power converter 17 and therefore to the set 2 of light-emitting diodes 3 . Diode 32 prevents return of the electrical energy stored in the capacitor 31 toward the coil 28 . The level of the dc voltage across the capacitor 31 and therefore the level of the LED supply dc voltage on the output 25 is adjusted by selecting the appropriate number of LEDs in series on subset 4 and varies with the type of LEDs as well as with temperature. Supply of coil 27 of the inductor device 30 is controlled by an output 34 of the controller 19 through the above mentioned MOSFET power transistor 33 . The current supplying the coil 27 is converted to a voltage signal by the inductor current sensor 35 connected between MOSFET transistor 33 and the ground. The inductor current sensor 35 comprises an output 55 for supplying the voltage signal to an input 36 of the controller 19 , and therefore to the multipler latch 53 . The current through the coil 27 is also measured through the additional coil 37 also wound on the core 29 of the inductor 30 . The current-reprerentative voltage appearing across the additional coil 37 is supplied, as mentioned hereinabove, to the input 38 of the controller 19 through the resistor 39 and therefore to the comparator 55 . The additional coil 37 is also connected to an accumulator 42 . formed by a capacitor 40 , through a diode 41 . The function of the accumulator 42 is to supply an input 43 of the controller 19 with a dc voltage amplitude higher than a minimum voltage reference to enable operation of the controller 19 . The capacitor 40 is charged through a branch switching device 45 and a resistor 46 . Input reference current sensor 51 is responsive to the full-wave rectified voltage at the output of the rectifier bridge 15 to supply on its output 52 the reference control voltage supplied to the multiplier 49 of the controller 19 . Upon switching the LED lamp 1 on, the capacitor 40 is discharged. In response to the full-wave rectified voltage which then appears at the output of the rectifier bridge 15 , the branch switching device 45 closes to allow the full-wave rectified voltage from the rectifier bridge 15 to charge the capacitor 40 through the resistor 46 until the voltage across the capacitor 40 exceeds the minimum voltage reference required to operate the controller 19 . Conduction of the MOSFET transistor 33 causes a current to flow through the sensor 35 which then produces on its output 55 a current signal applied to the multiplier latch 53 . Conduction of the MOSFET transistor 33 also causes current supply to the act 2 of light-emitting diodes 3 as described in the foregoing description, and to the current sensor circuit 10 to produce an input current feedback signal 24 supplied to controller 19 through the filter circuit 20 . It should be mentioned that since the reference control voltage is supplied to the multiplier 49 by the input reference current sensor 51 in response to the full-wave rectified signal from the rectifier bridge 15 , the amplitude of this reference control voltage and therefore the gain of the multiplier 49 varies with the amplitude of the full-wave rectified voltage. It should also be understood that every time the voltage signal from the inductor current sensor 35 , supplied to the multiplier latch 53 , exceeds the amplitude of the signal 50 from the multiplier 49 , the output of multiplier latch 53 (drive output) then passes from a high logic level to a low logic level to turn the MOSFET transistor 33 off, to thereby prevent that the dc current through the set 3 of light-emitting diodes 3 exceeds a safe level. Those of ordinary skill in the art will appreciate that the current flowing though the MOSFET transistor 33 is proportional to the full-wave rectified voltage at the output of the rectifier bridge 15 . The current waveform is sinusoidal and in phase with the voltage waveform so that the power factor is, if not equal to, close to unity. To further smoothen the current waveform and withdraw the MOSFET switching high frequencies therefrom, an EMI filter 44 can be added, as mentioned in the foregoing description, between the ac source 14 and the full-wave rectifier bridge 15 . To draw current from the ac source 14 throughout every cycle of the sinusoid, the supply voltage at the output 26 of the power converter 17 , i.e., the dc voltage across the capacitor 31 , must have an amplitude higher than the peak amplitude of the sinusoidal voltage of the ac source 14 . To enable reduction of the amplitude of the dc voltage across capacitor 31 to a value lower than the peak amplitude of the sinusoidal voltage of the ac source 14 , the key element of the “Boost” type topology of FIG. 1, i.e., the inductor 30 , has been modified. More specifically, the second multi-tap coil 28 has been wound onto the core 29 . The coils 27 and 28 act as the primary and secondary windings, respectively, of a transformer, and each tap 100 corresponds to a given level of the de voltage on the output 26 of the power converter 17 , each given level being of course lower in amplitude than the peak sinusoidal voltage of the ac source. Also, the number of turns associated to the different taps 100 of the coil 28 has been evaluated in relation to the number of turns of the coil 27 of the inductor 30 in order to produce transformation ratios as accurate as possible such that, irrespective of which tap 100 is used to obtain a given output voltage level, the controller 19 will behave in the same manner as when the do voltage at the output 26 of the power converter 17 is fixed and higher than the peak amplitude of the ac input voltage. Operation of the power factor controller 19 manufactured and commercialized by Motorola under the reference MC33262 is believed to be otherwise well know to those of ordinary skill in the art and, accordingly, Will not be further described in the present specification. Of course, it is within the scope of the present invention to use another type of feedback controller. Although the present invention has been described hereinabove by way of a preferred embodiment thereof, this embodiment can be modified at will, within the scope of the appended claims, without departing from the spirit and nature of the subject invention.

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BACKGROUND OF INVENTION 1. Field of the Invention The present invention relates in general to a damper mechanism for vehicle glove boxes and particularly to a damper mechanism which is utilizes a cam deflected spring to damp the downward movement of the glove box lid. 2. Description of the Related Art In order to improve the feel of smoothness and quality while opening a glove box door, various damping devices have been employed. Such devices include elaborate assemblies of springs, pistons, cams, cables and numerous other arrangements for slowing the descent of the glove box door as it is opened. This is especially desired in the current glove box doors which require a sheet metal liner to meet safety standards. For example, U.S. Pat. No. 4,886,311 issued Dec. 12, 1989 to Trube et al. teaches a glove box lock mechanism mounted in the dash panel. U.S. Pat. No. 5,292,159 issued Mar. 8, 1994 to Sandhu et al. teaches a flush mounted door latching mechanism for use with glove boxes. U.S. Pat. No. 5,385,378 issued Jan. 31, 1995 to Hakamada et al. teaches a glove box opening system that allows the glove box door to be opened further than the normal use position to allow access to the interior area of the dash board for servicing air conditioning or air bag units. U.S. Pat. No. 5,823,583 issued Oct. 20, 1998 to Sandhu et al. teaches a simplified three piece glove box latching mechanism. U.S. Pat. No. 5,868,448 issued Feb. 9, 1999 to Izumo teaches a glove box lid which opens upward instead of downward and a tensioning means to allow the raised glove box lit to remain open until forced downward by the user. U.S. Pat. No. 5,591,083 issued Sep. 14, 1999 to Bittinger et al. teaches damping a glove box door's movement using a compressible rubber wheel. U.S. Pat. No. 6,152,501 issued Nov. 28, 2000 to Magi et al. teaches a glove box door handle and latch assembly having a mounted door latch that is flush with the exterior door panel. U.S. Patent Application Publication Number 2002/0171248 published Nov. 21, 2002 to Diss et al. teaches a glove box latching assembly having a handle mounted flush with the exterior door panel. Thus there is still a need for an efficient, easy to assembly, cost effective, reduced breakage glove box door damping device. DISCLOSURE OF THE INVENTION The present invention provides advantages and alternatives over the prior art by providing a glove box damping assembly which may be molded-in reducing the manufacturing and assembly costs. According to a further aspect of the present invention, there is provided a glove box damper comprising: a cam assembly comprising a cam lobe attached substantially perpendicular to a pair of mounting spindles and at least two brackets for mounting said cam assembly along the bottom edge of a glove box lid, said glove box lid mounted along its lower edge to a glove box bin allowing said glove box lid to open in a downward direction; a spring assembly comprising body having an integral spring against which said cam lobe is biased and a pair of spindle mounting slots for positioning said cam assembly, mounted on an instrument panel retainer, thereby providing a damping of the downward opening movement of said glove box lid. According to yet another aspect of the present invention there is provided A glove box damper comprising: a cam assembly comprising a cam lobe attached substantially perpendicular to a pair of mounting spindles and at least two brackets for mounting said cam assembly along the bottom edge of a glove box lid, said glove box lid mounted along its lower edge to a glove box bin allowing said glove box lid to open in a downward direction; a spring assembly comprising body having an integral spring against which said cam lobe is biased and having a shape stopping the travel of the cam at a desired point, and a pair of spindle mounting slots for positioning said cam assembly, mounted on an instrument panel retainer, thereby providing a damping of the downward opening movement of said glove box lid as well as a desired amount of travel of said glove box lid. The present invention thus advantageously provides a glove box damper device which is easy to assembly, cost effective, has reduced breakage, and which provides a sense of smooth operation and quality construction to the user. BRIEF DESCRIPTION OF DRAWINGS FIG. 1 shows an exploded sectional partial side plan view of the glove box damper device of the present invention. FIG. 2 shows a perspective view of the cam portion of the glove box damper device of the present invention. FIG. 3 shows a perspective view of the spring portion of the glove box damper of the present invention FIG. 4 shows a plan front view of a portion of an instrument panel retainer containing a glove box opening having the springs and retaining slots for the damper device of the present invention. DETAILED DESCRIPTION Reference will now be made to the drawings, wherein to the extent possible like reference numerals are utilized to designate like components throughout the various views. Referring to FIG. 1, there is presented an exploded sectional partial plan view of a glove box assembly 100 having the damper device 10 of the present invention. The glove box assembly 100 comprising a glove box body or shell 101 and a glove box lid 102 as is typically mounted in a vehicle. As further shown in FIG. 1 the damper device 10 comprises a cam assembly 20 mounted on or molded into the glove box lid 102 and a spring portion 31 mounted on or molded into the I P retainer 30 . Referring now to FIG. 2, there is shown a perspective view of the cam assembly 20 having a cam lobe 1 , a pair of mounting spindles 2 and a pair of mounting brackets 3 . In practice the mounting spindles 2 are rotatively mounted in retaining slots 32 (FIG. 3) of instrument panel retainer 30 (FIG. 3 ). The cam lobe 1 being substantially perpendicular to mounting spindles 2 . The mounting brackets 3 are fixedly attached to the glove box lid 102 (FIG. 1 ). Turning now to FIG. 3, there is shown the instrument panel retainer 30 having a spring 31 of desired shape molded therein and further having molded therein a pair of retaining slots 32 configured to receive a corresponding pair of mounting spindles 2 (FIG. 2) of the cam assembly 20 (FIG. 2) of the present invention. The spindles 2 (FIG. 2) mounted in the retaining slots 32 position the cam 1 (FIG. 2) to ride against spring 31 . Also shown are mounting slots 33 which provide for easy insertion of the mounting spindles 2 (FIG. 2) into the retaining slots 32 . During the downward opening movement of the glove box lid 102 (FIG. 1) the spring 31 thus exerts a desired force against the rotational movement of cam 1 (FIG. 2) thereby damping and slowing the downward movement of the glove box lid 102 (FIG. 1 ). The spring 31 may also be configured to stop the rotational movement of the cam 1 (FIG. 2) at a predetermined point thereby limiting the opening travel of the glove box lid 102 (FIG. 1 ). Referring now to FIG. 4 there is shown a partial front plan view of an instrument panel retainer 30 having molded therein a plurality of springs 31 and corresponding plurality of paired retaining slots 32 of the present invention. The combination of a cam 1 rotating against a spring 31 results in a resistance to downward movement of the glove box lid 102 thereby giving a passenger operating the glove box a feeling of smooth operation combined with close fitting and accurate quality construction. At the same time this damper device assists in eliminating the sense of weight in the glove box lid 102 again providing a feeling of smooth operation and quality construction. In practice it is preferred for the spring to be about 30% to about one third compressed from its free position when the glove box lid is closed and about one half 50% compressed from its free position when the glove box lid is open. Different amounts of compression on the spring at both the open and closed positions of the glove box lid may be used to provide the desired effect of damping and slowing of the glove box lid travel. The damper device 10 of the present invention may be made of any suitable material or materials well known in this art. Particularly the damper device 10 of the present invention may be made of the same material at that of the instrument panel retainer or it may be made of a different material to achieve the desired properties of providing damping and slowing of the glove box lid during opening. Presently preferred materials include, for example, acrylonitrile-butadiene-styrene (ABS), polycarbonate/acrylonitrile-butadiene-styrene (PC/ABS), the engineered material sold under the brand name NOREL by General Electric Corporation, polypropylene, and other engineered materials well known in this art. It is also to be understood that the various parts of the damper device of the present invention may all be made of the same material or the various parts may of different materials. Although the preferred embodiments of the present invention has been disclosed in connection with one particular example, those skilled in the art will appreciate that various changes and modifications may be made without departing from the scope of the invention as set forth in the appended claims.

4y

FIELD OF INVENTION The present invention is directed to the field of garment hangers and is more particularly directed to a method for reusing hangers with size indicia mounted thereon. BACKGROUND OF INVENTION An article of clothing typically includes one or more labels located somewhere inside of the clothing article. The label usually includes size, fiber content and manufacturer details as well as information relating to country of origin and care instructions. In addition, a tag is attached to the article of clothing identifying the price of the garment as well as size. The tag often includes additional information relating to the store name, manufacturer and possibly a bar code which when scanned provides such information. In some cases a particular retailer or garment manufacturer has attached a further tag to the garment which bears a design that is in part colored to permit sorting according to some attribute of the garment such as style, color or size. For instance, the portion of the design that is colored may be blue to indicate a women's size 6 or green to indicate a women's size 8 or blue to indicate a men's size 44 or green to indicate a men's size 48. When such information is included on the tag attached to a garment, the consumer or retailer need not review the label of each item of clothing but merely locate the appropriately colored tag. However, tags are often attached to either the front, back or sleeve of the garment and thus, are not readily visible to either the retailer or the consumer. The retailer or consumer must rifle through the garments on the rack to locate the tags with the pertinent information. If the garment is not hung on a rack but folded in stacks (as is typical with sweaters and jeans) the tags are often tucked inside the garment for purposes of a neater display, thus, it is necessary to unfold the garment to find the appropriate information. Furthermore, there is virtually no uniformity between manufacturers and/or retailers as to the designation of the desired attribute of the clothing. For instance, the color blue may mean size 6 for one manufacturer or retailer but size 12 for another. Thus, the consumer is not aided by the color designation when visiting different areas of the store. Further, blue may refer to large in a men's jacket size but medium for men's slacks. For purposes of displaying garments suspended on hangers in an orderly and attractive manner to the retail customer, it is often desired to affix an indicating means on the hanger in a position visible to the retail customer while the hanger is suspended on a rack. The indicating means identifies some attribute of the garment suspended from the hanger, such as size, quality, color, manufacturing data, or pattern. The provision of a readily visible size indicator on a garment hanger is now accepted by retailers as a desirable addition to a garment hanger. To accommodate the various types of hangers available in the industry numerous indicating means have been developed in a variety of shapes, sizes and materials. Similarly, hangers have been developed to accommodate a variety of different indicating means. In Australian Pat. No. 638436 and corresponding U.S. Pat. No. 5,388,354, assigned to the assignee of the present invention, a low-profile molded plastic indicator for a garment hanger which requires limited modification to the hook of the hanger to enable the indicator to be securely attached to the top of the hook where it is most visible is described. The indicator is also designed to enable sorting into a predetermined orientation to enable automated handling and fitting of the indicators to hangers as described in U.S. Pat. Nos. 5,272,806 and 5,285,566 which are assigned to the assignee of the present invention. Such hangers and indicia are typically used only a single time and then shipped to either a landfill as waste or a recycling center where the plastic hangers are granulated into pellets which are then resold. However, landfills are taking up more and more space and recycling is often an expensive venture which renders such an option cost inefficient despite the need to conserve our environment's resources. Furthermore, many companies do not want to purchase recycled-content plastic products for either safety (i.e., food containers) or aesthetic purposes. SUMMARY OF INVENTION Accordingly, it is an object of the present invention to provide a method for reusing hangers having size indicia removably mounted thereon wherein plastic hangers used to display garments in a retail store are re-used several times before being shipped as waste or recycled. More particularly, the method of the present invention comprises: (a) shipping a first plurality of hangers to a plurality of clothing manufacturers at scattered geographic locals; (b) shipping a plurality of removable size indicia to the plurality of clothing manufacturers at the scattered geographic locals, the removable size indicia adapted to be removably secured to the first plurality of hangers; (c) assembling one hanger from said plurality of hangers with a garment and one of the removable size indicia, wherein the size indicia represents the size of the garment and the size indicia is preferably attached to the hanger automatically; (d) batching a plurality of the hangers with garments suspended therefrom and size indicia mounted thereon and then shipping the batch to a retail outlet for display and sale of the garments; (e) removing a definable percentage of the hangers with the size indicia mounted thereon from the garments as said garments are sold, and returning the defined percentage of hangers with size indicia to a reuse center; (f) removing the size indicia from the hangers at the reuse center and inspecting the hangers to obtain a plurality of selected hangers for reuse, wherein the removal of the size indicia from the hanger is preferably performed by automated removal; and (g) augmenting the selected hangers with newly molded hangers to provide the first plurality of hangers and repeating step (a) to form a loop for reused hangers. The method of the present invention particularly addresses environmental concerns to reduce plastic waste by reducing the overall number of plastic garment hangers being manufactured. The first plurality of hangers is molded and shipped to numerous clothing manufacturers in a variety of geographic locals throughout the world. In a preferred embodiment batches of the removable size indicia, which correspond to the hangers in the first plurality of hangers, are molded from plastic and then shipped to the various clothing manufacturers. The batches are typically molded by size and color to form batches of color coded size indicia in a plurality of different colors. In a preferred embodiment the batches of color coded size indicia are bundled into stacks and automatically attached to the hangers. To ensure color uniformity the color coded size indicia can be molded at a single location. Each size indicia is mounted on a hanger from which a garment is also suspended such that the size of the garment corresponds to the size indicia. Groups of hangers with size indicia mounted thereon and garments suspended therefrom are organized according to a retail store's order and then the batch of hangers with size indicia and garments are shipped to a retail store or retail distribution center for display and sale of the garments. Such garments are floor ready meaning that the garment can literally go from the packing box to the rack for display. Much of the back room sorting, sizing and pricing is eliminated. Because the garments arrive at the store already hung on hangers, the number of hangers the store is required to store is also vastly reduced. It will be noted that when the hangers with garments and size indicia may be shipped to a retail distribution center, the center then forwards the appropriate number of such items to the appropriate retail store. In the present method as the garments are sold in the retail store the hangers with size indicia are removed from the garments and separately packaged for return shipment to a reuse center. The number of hangers set aside for reuse is a definable percentage taking into account that some customers will request that they be permitted to keep a hanger at the point of sale and that hangers may be inadvertently damaged, thrown out or kept by a store. In a preferred embodiment the definable percentage of hangers removed for reuse is 65% to 90%. It has been found that about 10% to 35% of the hangers identified as the first plurality of hangers will be unrecoverable. At the reuse center the size indicia are automatically removed from the hangers and the hangers are inspected for damage or other contamination. The non-damaged and non-contaminated hangers are selected for reuse. It is contemplated that about 10-30% of the returned hangers will be unrecoverable which means that in a preferred embodiment the number of hangers selected for reuse constitutes about 50% to 80% of the first plurality of hangers originally molded and sent to the garment manufacturers. In a preferred embodiment the hangers not selected for reuse are ground into pellets and either recycled or sold as scrap plastic. In a preferred embodiment the recycled plastic is ground, fed into a hopper and melted down in a barrel extruder to form a molten plastic which is then injected into a mold machine to form recycled plastic hangers for retail consumer usage. The consumer grade hangers are then returned to the retail store for sale. The hangers which are selected for reuse are returned to garment manufacturers and batched with newly molded hangers to repeat the present process. Statistical averages indicate that a hanger will complete 2 to 6 loops of reuse before being considered unrecoverable. Typically the hangers are cleaned before being returned to the garment manufacturers for reuse. Since fewer than 100% of the hangers are reused it is necessary to augment the supply of hangers being reused with newly molded hangers in order to maintain a constant adequate supply. In the preferred embodiment the supply of selected hangers is augmented with about 20 to 50% of the number of the first plurality of hangers. However, the number of overall hangers which are molded is less than if there was no reuse. In yet another embodiment the present invention contemplates the reuse of the color coded indicia. Accordingly, the present method further includes the steps of sorting the removed size indicia from the hangers by color. If different size designations are utilized for the same color coded size indicia then a secondary sort by size must also be completed. The sorted size indicia would then be bundled and shipped to the garment manufacturers for mounting on hangers. In a preferred embodiment the method further includes the step of washing the color coded size indicia. BRIEF DESCRIPTION OF THE FIGURES The foregoing and other objects of the invention may now be more readily ascertained from the following detailed description of the preferred embodiments thereof, taken in conjunction with the accompanying drawings, in which: FIG. 1 illustrates a hanger hook with a color coded size cap mounted thereon that is useful in the practice of the present invention; FIG. 2 is a cross section taken along section lines 2 - 2 ′ of FIG. 1 which illustrates the interior construction of the hanger and hook combination illustrated in FIG. 1; FIG. 3 is an illustration of a common color code assigned to various sub-sets of the plurality of graded size, as determined by large scale consumer demographics; FIG. 4 is an illustration of one set of common size designations illustrating a sub-set of the plurality of graded sizes of the present invention; FIG. 5 is an illustration of one family of hanger designs that may be used throughout a retail clothing store to uniformly display the articles of clothing for sale, and to display the color codes of the present invention; FIGS. 6 ( a ), 6 ( b ) and 6 ( c ) are three drawings, which when combined as indicated thereon, illustrate one representative example of a color code scheme of the present invention; FIG. 7 is an isometric view of a mechanism useful in the automatic assembly of the color coded index caps and hangers of the present invention; FIG. 8 is an plan view of the mechanism shown in FIG. 7 illustrating the assembly of a color coded index cap to a hanger as taught by the present invention; FIG. 9 is an isometric view of a mechanism useful in the dis-assembly of the color coded index caps from the hangers to enable reuse of the hangers; FIGS. 10 ( a ), 10 ( b ) and 10 ( c ) illustrate in sequence the operation of the mechanism illustrated in FIG. 9 as the hanger and color coded index cap are disassembled; and FIG. 11 illustrates a diagram for implementing the method for re-using hangers having size indicia. DETAILED DESCRIPTION OF THE INVENTION Referring now in detail to the drawings, and to the embodiments depicted in FIGS. 1 and 2, there is illustrated a hanger hook 2 with a color coded size cap 18 mounted thereon that is useful in the practice of the present invention. The hook 2 of a molded plastic garment hanger is shown in simplified form and is adapted to engage a rod or other supporting means. In practice the hook typically includes the strengthening ribs 12 a , 12 b around the perimeter of the hook. It will be noted that in FIGS. 1 and 2, the body and clips of the hanger are not depicted. The body and clip structure of the hanger can take on many different types of configurations as long as the hanger supports the garments suspended thereon. In FIG. 5, several exemplary hanger styles which will accommodate a variety of types of clothing are depicted. Each of the hangers shown in FIG. 5 includes a means for attaching a color coded size cap 18 . The color coded size cap 18 which is mounted on the hanger is more clearly illustrated in FIG. 2 . As shown therein the size cap includes side walls 20 , 22 formed with at least one retention aperture 24 , 26 , as described in Australian Pat. No. 638436 and U.S. Pat. No. 5,388,354, the contents of which are incorporated into this specification by cross-reference. The apertures 24 , 26 define through-openings which facilitate stacking of the indicator 18 with other indicators prior to fitting to a hanger. The indicator is retained on the hook by an indicator attachment mechanism. As illustrated in FIGS. 1 and 2 the hook 2 is formed with a flange 14 defining a top region 16 , which in a preferred embodiment is flattened and slightly larger in peripheral dimensions than the lowermost portion of an indicator 18 . An upstanding web 4 extends centrally from the top region 16 of the hook 2 . The web 4 can be shaped similarly to the shape of the cavity of the indicator 18 so as to comfortably fit within that cavity. As one alternative, the web 4 can be shaped to follow the normal contour of the hanger hook. The web 4 is formed with integrally molded indicator attachment means 28 . In the present embodiment the indicator attachment means includes central opening 6 from the upper portion of which a resilient detent leg 8 extends downwardly terminating in a laterally projecting portion 30 configured to engage one of the apertures 24 or 26 in the side wall of the indicator 18 , as shown in FIG. 2 . Since the detent leg 8 is narrow and is resiliently connected to web 4 , it is easily deflected laterally by means of a probe or pin inserted into the aperture 24 or 26 which engages laterally projecting portion 30 to displace laterally projecting portion 30 toward the plane of the web to clear the aperture 24 or 26 and allow the indicator to be removed from the web 4 . This operation can be achieved simply and quickly with little or no damage to the indicator 18 or the attachment means 28 . Nevertheless, while the laterally projecting portion 30 remains in the position shown in FIG. 2 of the drawings, the indicator 18 will remain securely fastened to the web 4 and will withstand all usual handling operations to which the hanger is subjected in day-to-day use. To improve the flexibility of the detent leg 8 , it can be reduced in thickness as shown at 200 in FIG. 2 of the drawings. Other means for attaching indicators to hangers can be utilized, such as the means described in U.S. Pat. No. 5,388,354, wherein the indicator may also be retained on the hook by means of at least one abutment projecting from the hook which engages an aperture in the side wall of the indicator. However, when the indicator is retained by an abutment, the indicator is not easily removed from the hanger and either the hanger or the indicator may be damaged during the process. In the preferred embodiment of the present invention the size cap shown is of a rectangular configuration, see for example, FIGS. 1 and 3, and presented at the top of the hook. However, other shapes and configurations of size caps can be used in accordance with the present invention. The indicator 18 of the preferred embodiment has been particularly well-received by retailers and consumers in the method and system for color coding sizes of clothing on display which is also useful in the practice of the present invention. In the present method and system, individual articles of clothing are classified according to line, such as men's apparel, women's apparel, infant and toddler apparel, youth apparel, girl's apparel, boy's apparel, intimate apparel, men's apparel sized by waist, women's apparel sized by waist, petite apparel and plus apparel. Each line of clothing is then further classified according to type of clothing. For instance, further classification in the women's line includes dresses, shirts, blouses, skirts, slacks, suits, sweaters, coats, jackets, panties, bras, and bathing suits. Each of these lines of clothing is then segregated into a plurality of graded sizes with a plurality of common size designations that appear in all of the clothing lines. Common size designations may include XXS (extra, extra-small), XS(extra-small), P/S (petite/small), S(small), S/M (small/medium), M(medium), M/L(medium/large), L(large), L/XL (large/extra-large), XL(extra-large), XXL(extra-extra-large) and XXXL (extra-extra-extra large). Of these designations S, M, L and XL are almost universally available. Each of these common size designations designates clothes intended to fit consumers of a particular physiology. In some situations, typically, when the clothing is more tailored, a more specific size designation is required and the size designations are referenced by numerals such as 2, 4, 6, 8, 10, 12, 16, 18 and 20; 1, 3, 5, 7, 9, 11 and 13; or 3/4, 5/6, 7/8, 9/10, 11/12, 13/14 and 15/16, which would appear in numerous clothing lines. The particular graded sizes in different clothing lines that would be selected by a consumer selecting clothing appropriate for a particular physiology is then identified and a color code assigned to each graded size designation to form a matched set of graded sizes common to a specific consumer profile. The clothing is displayed on a hanger with a color coded size cap mounted thereon such that the color of the size cap conforms to the assigned color code. For instance, in the color coding system illustrated in FIG. 3, the color blue has been assigned 7 different size designations: L, M/L, 24 M, 9, 9/10, 24 W and 38. As indicated by the sizes matched in this set, the blue color indicates a large size clothing. In women's apparel, the sizing used in different lines of clothing would typically be L or M/L and 9 or 9/10 to designate a particular physiology profile. A women of this physiology would know by using the color coding method and system of the present invention that she could look for garments hung on a hanger with a blue size cap to find clothes that matched her physiology. In infant's apparel the sizing would typically be either large or 24 months both of which identify garments that would fit an infant of a particular physiology. Thus, the consumer could then look for garments hung on hangers with a blue size cap to find appropriate garments. It will be noted that the same color designating the larger sized clothing in the women's apparel line is used to designate the larger sized clothing in the infant apparel line. This system can be followed in garments sized by waist, where for instance the blue color indicates a 38 waist and also in the plus-sized apparel to designate a 24W, where the plus-sized line of clothing runs from size 16W to 26W. This system permits the purchaser to move from department to department of a retail store and find articles of clothing appropriate to fit a particular physiology based on the color coding of the sizes. Furthermore, this same consumer can make purchases for others knowing only the bare basics of the recipient's physiology. FIG. 4 illustrates one set of common size designations showing a subset of the plurality of graded sizes of the present invention wherein: lemon designates XXL purple designates XL or L/XL blue designates L or M/L green designates M yellow designates S pink designates XXS. A different color designates each graded size in this universal system of sizing. It will be noted that there are two size designations for purple and blue. This is possible because a single manufacturer of clothing would not typically use both forms of sizing for the same type of garment. However, both forms of sizing may be found in a single classification of clothing. By designating all clothing that can fit a specifically sized person with a single color the consumer then easily knows to look for that color size cap when selecting clothing on display. FIG. 5 illustrates one family of hanger designs that may be used throughout a retail clothing store to uniformly display the articles of clothing for sale and to display the color codes of the present invention. Hangers 300 , 302 and 304 are typically used to hang tops such as shirts, blouses, dresses, coats, jackets, robes, nightgowns, rompers, overalls, swimwear and sweaters. Hanger 300 which is 12 inches long can be used to hang infant and toddler tops, hanger 302 which is 14 inches long can be used to hang kids tops and hanger 304 which is 17 inches long can be used to hang adult tops. Hangers 306 , 308 and 310 are typically used to hang bottoms such as slacks, denims and skirts. Hanger 306 which is 8 inches long can be used to hang infant and toddler bottoms, hanger 308 which is 10 inches long can be used to hang children's bottoms and hanger 310 which is 12 inches long can be used to hang adult bottoms. Hanger 312 can be used to hang bras, panties, slips and bathing suits. A hanger body length of about 10 inches is preferred to accommodate a variety of different sizes. Hanger 314 is a frame hanger which can be used to hang infant and toddler separates and coordinates. The varying lengths of hangers 300 - 310 accommodate virtually all of the different lines of clothing ranging from infants to plus sizes. Each of these hangers includes an indicator attachment mechanism as described previously herein to display the color coded size caps described herein at the top of the hook. Typically a retail store utilizes many different hanger designs depending upon the type of garment and the manufacturer. Limiting the number of hangers used throughout the store to about eight different designs is an extremely cost-effective maneuver which will also standardize the display and result in a neater appearance. However, it will be noted that the eight designs of FIG. 5 constitute a preferred embodiment of the present invention. Any hanger with an indicator attachment mechanism suitable for receiving a color coded size cap can be used in the method and system of the present invention. FIGS. 6 ( a ), 6 ( b ) and 6 ( c ) illustrate one representative example of a color code scheme of the present invention which can accommodate the sizing needs of all lines of clothing and departments in a large retail store. At the far left of FIG. 6 ( a ) designated as Rows A-G are a plurality of size classifications which would be appropriate for a plurality of clothing lines are designated as universal, tall/multi, infant or toddlers, metric, multi-sizes, plus-size and waist sizes. It will be noted that more than one size classification may be found in a single line of clothing. For instance, in women's apparel, clothing may be sized in universal sizes (Row A), metric sizes (Row D) (typically, odd numbers, even numbers or multi-sizes), plus sizes (Row F) or by waist (Row G). To the right of each class designation in each row is a series of graded size designations appropriate for each class. The size designations are based on large scale consumer physiological demographics, so that in identifying the graded size for an item of clothing sized by a waist size, the size identified is common to the graded size of an item of clothing sized by chest size or universal size for the same consumer physiological profile. The particular graded sizes in different clothing lines that would be selected by a consumer for a specified physiological profile are set forth in columns each of which are assigned a color. Each color designates a specific size which will fit a consumer of a particular physiological profile. The color coded size cap mounted on the hanger (such as any hanger depicted in FIG. 5) from which the garment is suspended can be used to determine which clothing on display is to be selected to form a matched set of graded sizes common to a specific consumer physiology. About 16 different colors are needed to differentiate between all of the different sizes. One family of colors is set forth in FIG. 6 in Columns 1 - 20 , which includes: lemon (Pantone 101 U), pink (Pantone 189 U), aqua (Pantone 326 U), red (Pantone 192 U), tan (Pantone 145 U), yellow (Pantone 121 U), light blue (Pantone 306 U), green (Pantone 340 U), sky blue (Pantone 2975 U), light purple (Pantone 2715 U), olive (Pantone 398 U), blue (Pantone 285 U), orange (Pantone 165 U), dark purple (Pantone 2593 U), light green (Pantone 375 U) and burgundy (Pantone 246 U). Colors can be reused in different lines of clothing where the sizes do not overlap but still typically designate either a larger, smaller or medium size. For instance in the present embodiment it will be noted that the colors yellow, aqua, tan and sky blue have been used more than once in designating a physiological profile. Using the color aqua (Columns 3 and 18 ) as an example, the sizes 2 and waist 29 designate one physiological profile, while XXXL, 15 and 15/16 designate a completely separate physiological consumer profile. There would be no overlap in the lines of clothing sought by individuals between these two size groups. The size 4T is also designated by the color aqua. Again this size does not overlap with either of the other two size groups which renders it permissible to reuse the color in the toddler line. Also it is noted that the size 4T is one of the largest toddler sizes bringing the use of the color in line with its larger size designation. When a color is used to designate a multitude of sizes in non overlapping lines of clothing it will not be a color used to designate one of the more common sizes such as S, M or L. However, typically a color will only be used once to designate a single physiological profile. More than 70% of all size caps will fall into one of five colors that designates the physiological profile for the following universal sizes: XS, S, M, L and XL and the corresponding size classes designated by row. To enhance the visibility of these size caps for these most common sizes the size caps are assigned the brightest and most basic colors, respectively-red, yellow, green, blue and purple. Blue for instance designates a large size in the present embodiment as discussed previously with respect to FIG. 3 . Yellow designates the size small. Corresponding to this physiological profile for a women's line of clothing are the sizes S, 5, 5/6, and waist 32. Clothes marked with these sizes would all fit a women of a particular physiological profile. The sizes S and 12M also would fit an infant of a particular physiological profile and the size 20W is considered to be a small plus-sized garment. Accordingly, attaching a yellow size cap to the hangers from which each of these garments are suspended would enable a consumer to match up all the different clothes from numerous clothing lines and by numerous manufacturers which fit a particular physiology identified as being small. Thus, the consumer could move from department to department reviewing numerous lines of clothing from slacks, to suits, to coats, to dresses, to intimate apparel and find the size appropriate for that consumer's particular physiological profile. The consumer would even recognize the color as designating a particular size profile in other lines of clothing, such as an infant or men's apparel. By placing a color coded size cap at the top of each hanger the consumer is greatly aided in locating all garments designed to fit a particular physiological profile in numerous different departments from different clothing lines no matter how the garment is sized, universally or metrically. This also aids the salesperson who is assisting the consumer in looking for a particular garment either on the floor of the store as well as in the back rooms of the store where any additional garments are stored, replenishing a rack of clothing, organizing a rack of clothing according to size or re-organizing a rack of clothing by size at the end of the day. It is also contemplated that in the preferred embodiment of the system of the present invention the color coded size caps and the garments are assembled at the point of manufacture and arrive at the store already on the hanger. This means that the actual matching of the color coded size cap and an article of clothing takes places before shipment of the garment from the manufacturer. The garment arrives at the retail store, floor ready. The prehung color coded sized garments need only be removed from a box and hung on the rack. Most of the typical back room work in a retail store is eliminated, thus making the system of the present invention extremely cost-efficient. In a preferred embodiment, the attachment of the color coded size cap to the hanger is performed automatically at the time the garment is hung. Although the attachment could also be by manual means. One such means for automatically attaching a color coded size cap to hanger is illustrated in FIGS. 7 and 8 and is more specifically described in U.S. Pat. Nos. 5,272,806; 5,285,566 and 5,507,087, the contents of which are incorporated herein by reference. It will be noted that each of these patents is assigned to the assignee of the present invention. In the illustrated embodiment of a system for attaching an indicator to a hanger, the attaching means includes a pair of magazine towers 101 and 102 dimensioned to contain a vertical stack of hangers therebetween and a third magazine 108 which receives a bundle of stacked indexing caps. The hangers rest on platen member 104 and are selectively engaged by a reciprocating plate 105 which includes a cutout 105 a conforming to the exterior dimensions of the index coded cap 18 . Immediately adjacent cut-out 105 a are alignment cams 109 . The ends 111 a , 111 b of reciprocating plate 105 provide a spring loaded tip for engagement of the hanger 11 . In addition, the magazines 101 and 102 are independently adjustable by means of bracket 110 and support 112 to configure the system to a wide variety of hanger shapes including those depicted in FIG. 5 . Each of the magazines 101 , 102 and 108 have cut-outs 101 a , 102 a which allow the hangers and index caps to be withdrawn from the magazines as plate means 105 reciprocates forwardly as illustrated in FIG. 7 . Stand-off legs 113 - 115 are used to elevate the system above the employee work bench, to assist the operator in draping the article of clothing about the hanger before the hanger is withdrawn from the system. Alternately, the individual legs can be altered in length to provide a slanted configuration which will facilitate hanging clothes therefrom. As illustrated in FIG. 8, the system is loaded with a bundle of stacked caps indicated at 18 which are loaded into magazine 108 . Magazine 108 is suspended above the reciprocating plate 105 and platen 104 by brackets 116 , 117 . Prior to engagement with the hanger 11 the spring loaded tips 111 a , 111 b of reciprocating plate 105 are fully distended. As plate 105 moves forward, or downwardly as illustrated in FIG. 8, it first engages an index cap from the stack of caps 18 within recess 105 a . The alignment surface 109 centers the hook 2 within the reciprocating plate 105 so that the indicator attachment mechanism on the hook is properly aligned with the index cap 18 during attachment. Plate 105 is dimensioned such that the index cap is seated on hook 2 by the impact of plate 105 as the floating spring loaded tips 111 a , 111 b engage the center portion of hanger 11 . The hanger is then driven forwardly out of the magazines 101 , 102 to the position illustrated by the dotted lines in FIG. 8 . The hanger engages eccentric stops 106 a , 106 b and displaces the end portion of platen 104 outwardly as illustrated in FIG. 8 . The spring loaded tips 111 a and 111 b compensate for irregularities in hanger molding and reduce the impact of the reciprocating plate 105 on the central portion of the hanger. This substantially eliminates the broken and shattered hangers normally encountered in this type of device. As the pneumatic cylinder 103 drives platen 104 , the spring loaded tips 111 a , 111 b are compressed, and the spring loaded platen 107 is between platen 104 , and platen 107 . As illustrated in FIG. 8, the hanger is now presented to the operator with the clips 32 a - 32 b suspended above the work space and free from any immediately adjacent encumbrances, so that the operator may quickly and easily attach a garment thereto. As the article of clothing is attached to the hanger, it is lifted free of the spring loaded tips 111 a , 111 b of platen 105 , which allows platen 107 to close thereby actuating the control mechanism for the system to return reciprocating plate 105 back to its original starting position. If set on automatic, as soon as the plate 105 has reciprocated to its fully retracted position, it is reciprocated forward to automatically dispense another index coded cap and hanger. In still another embodiment the system for color coding sizes of clothing displayed in retail clothing stores includes automatic means for removing the color coded index caps to the hangers. FIGS. 9 and 10 ( a ), ( b ) and ( c ) illustrate one such means for removal wherein the indicator attachment mechanism is of the embodiment depicted in FIGS. 1 and 2 herein. The laterally extending portion 30 of the indicator attachment mechanism is easily deflected by means of a pin 220 inserted in the aperture 24 of indicator 18 which engages the laterally extending portion to displace it towards the plane of web 4 to clear the aperture 24 and allow the indicator 18 to be removed from the hanger 1 . Using this system, which is described more particularly in International Application No. PCT/US96/01286 the contents of which are incorporated herein by reference thereto, the color coded indexing caps can be automatically removed from their respective hangers 1 . In this embodiment the hanger 1 is fed to the apparatus for removing the color coded index cap by a feeding rail 205 . The feeding rail is inclined so that the hangers 1 move downwardly toward the apparatus by gravity. To initiate the process the hangers 1 can be placed onto the feeding rail 205 manually or automatically. Other means to feed hangers 1 to the apparatus can comprise a screw conveyor, a belt conveyor, or any other appropriate means to carry the hangers toward the apparatus. The apparatus of the present embodiment includes a front plate 206 , a back plate 107 and an actuating means 208 . Front plate 206 and back plate 207 are arranged vertically and are facing each other. In the embodiment shown in FIG. 9, the two plates 206 and 207 are almost quadratic, however, any other appropriate shape, for example rectangular, can be used. The actuating means 208 includes a pneumatically driven escapement valve with two rods. Each of the rods is connected to the plate 206 or 207 via respective connecting means 209 and 210 . In use, the actuating means 208 moves the front plate 206 and the back plate 207 parallel to each other in a vertical plane. This movement is periodically repeated to permit the removal of cap from one hanger after another. Back plate 207 has a recess 219 positioned on an outer portion of the surface facing the front plate 206 . Recess 219 is dimensioned to correspond to the dimensions of indicator 18 , so that when a hanger 1 is pressed against the back plate 207 , the indicator 18 is received in the recess 219 . A pin 220 is provided on the back wall of the recess 219 in a position corresponding to the aperture 24 of the indicator 18 . The dimensions, such as the size and the shape, of the pin 220 are selected according to the dimensions, particularly, the shape and the depth, of the aperture 24 , so that the pin 220 enters the aperture 24 and is able to displace the laterally projecting portion 30 of the web 4 of the hanger 1 to clear the aperture 24 , and permit the indicator 18 to be removed from the hanger 1 . In the preferred embodiment of FIG. 9, the pin 220 has a rectangular cross-section, but another appropriate shape can be used. Front plate 206 includes a through-opening or window 218 . Window 218 is preferably dimensioned to correspond to the configuration of recess 219 of back plate 207 . However, the window 218 can have any appropriate shape, as long as the indicator can pass through it. When back plate 207 is in its upper position and the front plate 206 is in its lower position, the recess 219 and the window 218 match, so that the indicator 18 can be removed from the recess 219 through the window 218 . In the described embodiment the preferred method for removal of the indicator 18 from recess 219 is by means of an air blast through aperture 221 in the back wall of recess 219 . Aperture 221 is connected to an air control means by means of a tube 227 , shown in FIG. 10 ( c ). The air blast through the opening 221 is controlled so that when the back plate 207 reaches its upper position, and the front plate 206 is in its lower position, the air blast is generated or enabled, which pushes the indicator 18 through the window 218 of front plate 206 . The released indicator passes through the window 218 and is collected by a discharge tube or chute 224 , positioned in front of the window 218 and leads the released indicator to a container 225 (shown in FIGS. 10 ( a ) and 10 ( c )). The feeding rail 205 extends under the two plates 206 and 207 . The distance between the plates 206 and 207 and the feeding rail 205 when the plates are in their lower positions is preferably such that pin 220 of back plate 207 will be aligned with aperture 24 of indicator 18 . The height of the assembly is adjusted to provide an automatic operation for different styles of hangers and hooks. As illustrated in FIG. 9 the back plate 207 is in its lower position and the front plate 206 is in its upper position. When hanger 1 moves down the feeding rail 205 toward the decapping apparatus the movement of the hanger 1 is stopped by the back plate 207 . FIGS. 10 ( a ), 10 ( b ) and 10 ( c ) illustrate the sequence of the operation for automatically removing color coded index caps from hangers in accordance with the present invention. More particularly, FIG. 10 ( a ) illustrates the start of the cycle for removing color coded index caps 18 from a plurality of hangers. As shown, it will be noted that the back plate 207 is lowered to its lowermost position and a plurality of hangers are waiting in front of the decapping apparatus on the feeding rail 205 in line for removal of the indicator caps 18 one after the other. The front plate 206 is raised but only needs to be raised upwardly until it no longer covers the recess 219 . In other words, the amplitude of the movement of the plates 206 and 207 has to be at least the height of the recess 219 , so that the indicator 18 can be received in the recess 219 . Gravity pushes the foremost hanger with indicator into the recess 219 of back plate 207 . After the indicator 18 is received in the recess 219 of the back plate 207 , the front plate 206 is moved downwardly to seat the indicator 18 firmly or at least to hold the indicator firmly in the recess 219 of the back plate 207 . In this position the pin 220 of the back plate 207 displaces the laterally extending portion 30 of the hanger 1 , to permit the release of the indicator 18 from the hanger 1 . The pin 220 is long enough to fully displace the laterally extending position 30 from the recess 24 of indicator 18 , but is not long enough to engage the aperture 6 of hook 2 . FIG. 10 ( b ) illustrates the sequence of removing the indicator 18 from a hanger 1 mid-cycle when both the front and back plates 206 and 207 are in their lower positions. After the pin 220 releases the indicator attachment mechanism the front plate 206 is lowered to separate the released indicator and hanger 1 from the rest of the hangers and also to engage the foremost hanger 1 . To assist in the separation of the foremost hanger 1 with the released indicator from the other hangers the lower edge 246 of the front plate 206 can be beveled. The beveled lower edge 246 of the front plate 206 holds the hanger 1 down by abutting against the edge of the top region 16 of the hook of the hanger 1 . As shown in FIGS. 10 ( a )- 10 ( c ) lower edge 246 of front plate 206 is beveled towards the back plate 207 . As one alternative, lower edge 246 can have a step-shape. FIG. 10 ( c ) illustrates the end of the cycle wherein the pin 220 has displaced the laterally extending portion 30 from the indicator 18 , and the indicator may be removed from hanger 1 when the back plate 207 is moved upwardly to its upper position, while the front plate 206 stays in its lower position. Since pin 220 of the back plate 207 extends into the aperture 24 of the indicator 18 , the back plate 207 carries the indicator 18 upwardly. The front plate 106 engages hanger 1 and prevents the hanger 1 from also being carried upwardly. Consequently, the pin 220 has two functions: displacing the laterally extending portion 30 of the hanger 1 to release the indicator 18 from the hanger 1 and carrying the indicator 18 upwardly to separate the indicator 18 from the hanger 1 . As previously described the indicator 18 is preferably removed from recess 219 by means of air blast through aperture 221 in back plate 207 . The air blast pushes the indicator 18 through the window 218 of the front plate 206 . The released indicator 18 passes through the window 218 of the front plate 206 and is collected by a discharge tube 224 , which is positioned in front of the window 218 and leads the released indicator to a container 225 . Upon removal of the indicator 18 from hanger 1 and after back plate 207 is moved upwardly, hanger 1 continues to slide down the feeding rail 205 . As illustrated in FIG. 10 ( c ), hanger 1 with web 4 is moving down the feeding rail 205 after being decapped. The decapped hanger is either collected manually or automatically therefrom, for example by means of a screw conveyor, which can collect decapped hangers from a plurality of feeding rails 205 coming from respective decapping apparatuses. As illustrated in FIGS. 9 and 10 ( a ), the automatic means for removing indicators from hangers is driven pneumatically, and further comprises position control means 211 , air control means 214 , a first timer 216 , a second timer 217 , and an air valve 237 . The air valve 237 generates and/or controls the pressurized air, by which the decapping apparatus according to the preferred embodiment of the present invention is controlled and driven. The air valve 237 , the timers 216 and 217 , the actuating means 208 , the air control means 240 and the position control means 211 respectively are connected by air tubes for pneumatic control. Also, the entire apparatus is held and fixed to a holding means (not shown). As shown in FIG. 10 ( a ), the position control means 211 comprises a first detector 212 for the position of the front plate 206 and a second detector 213 for the position of the back plate 207 . The first detector 212 and the second detector 213 work on a pneumatical basis and have a similar structure. First and second detectors 212 and 213 each include generally a cylindrical tube illustrated by 244 and 245 , respectively, and pistons 222 and 223 , respectively, which are movable within each of said cylindrical tubes 244 and 246 . The outer ends of pistons 222 and 223 are provided with contact plates, which are contacted by the upper sides of the front plate 206 and the back plate 207 , respectively. In the upper position, the front plate 206 and the back plate 207 press inwardly pistons 222 and 223 , respectively, and cause a pneumatic signal in the position control means 211 , thereby permitting a steady control of the position and the movement of the plates 206 and 207 . FIG. 10 ( a ) shows a cross section of the control means 211 and the plates 206 and 207 , whereby the position of the plates 206 and 207 is the same as in FIG. 9 . Also, the discharge tube 224 and a collecting container 225 for the released indicators 18 are illustrated. FIG. 10 ( c ) illustrates a side view of the air control means 214 and the tube plates 206 and 207 . The air control means 214 comprises a third detector 215 for detecting the position of the back plate 207 . Third detector 215 has a cylindrical tube 249 and a piston 226 , which, generally have the same shape and function as the first and second position detectors 212 and 213 as described above. In FIG. 10 ( c ), the back plate 207 is in its upper position, and the front plate 206 is in its lower position. The back plate having released and carried a indicator 18 upwardly from hanger 1 , contacts a contact plate 226 of the position detector 215 and moves the contact plate 226 together with its piston into the cylindrical tube of the detector 215 . This causes a pneumatic signal within the air control means 214 , which enables a pressurized air blast through a tube 227 , which is connected to the opening 221 of the back plate 207 by appropriate connection 228 . The air blast through the opening 221 ejects the released indicator 18 through the window 218 of the front plate 206 into the discharge tube 224 . The arrow in FIG. 10 ( c ) indicates the direction of the movement of the indicator 18 . In operation, the back plate 207 moves downwardly to its lower position, which is followed by an upward movement of the front plate 206 to its upper position. The whole movement cycle is repeated periodically, so that a plurality of hangers 1 can be decapped easily and reliably in an automated process. Since one of the plates 206 and 207 is always in its respective lower position, there will be always a number of hangers 1 on the feeding rail 205 waiting to be decapped one after another, as shown in FIGS. 10 ( a )- 10 ( c ). The actuating means 208 controls the movement of the two plates 206 and 207 , so that the front plate 206 cannot move upwardly when the back plate 207 is not in its lower position, and the back plate 207 cannot move upwardly when the front plate 206 is not in its lower position. This ensures that the hangers to be decapped do not slide along the feeding rail 205 under the plates 206 and 207 without being decapped. The first timer 216 controls the regular cycle of the movement of the two plates 206 and 207 , whereas the second timer 217 enables a repeated downward movement of the front plate 206 . If, for example the hook of the hanger 1 is bent or damaged, or the indicator 18 is bent or damaged, the front plate 206 is not permitted to slide downwardly to press or hold the indicator 18 into the recess 219 , since its lower edge contacts the upper edge of the indicator 18 and is therefore restricted in its downward movement. In this case, the timer 217 gives a signal to the actuating means 208 to lift the front plate 206 up again and retry to move it downwardly. This is repeated, until the indicator 18 is properly received in the recess 219 of the back plate 207 and the front plate 206 can move to its lower position without resistance. This problem can already partially be avoided by an appropriate angle or bend of the lower edge of the front plate 206 , as discussed above. Although the system of FIGS. 9 and 10 has been illustrated with only one style of hanger shown in FIG. 5, it is contemplated that a hanger of any other style, including the styles shown in FIG. 5, could be substituted therefore. As illustrated in FIG. 11, a method for re-using hangers having size indicia removably mounted thereon is illustrated in a schematic flowchart form. A hanger manufacturing center 401 molds hangers and ships the hangers via distribution channel 403 to a plurality of garment manufacturers 405 at scattered geographic locales. While a single group of garment manufacturers 405 are illustrated in FIG. 11, it should be noted that in actual practice, there may be hundreds of garment manufacturers that supply garments to any large retail outlet. Simultaneously, a plurality of removable size indicia are molded at 407 and shipped in bundles 413 of size indicia via distribution channel 409 to these same garment manufacturers 405 . At each of the plurality of garment manufacturers 405 , a single hanger 411 and a single index cap from bundle 413 are assembled with the garment manufactured by the U.S. garment manufacturing facility at that geographic local. The size indicia represents at least one characteristic of the garment, and preferably indicates the size of the garment as denoted in the country in which the retail store to which the garment is to be shipped, is located. A plurality of hangers, garments and size indicia are then batched as illustrated at 415 , and the batch is shipped to a retail store 419 or a regional distribution center 417 operated by the retail store chain 419 . The regional distribution center 417 provides a supply of garments on hangers 421 to the various retail stores 419 at scattered geographic locations for sale to consumers. At the point of sale in the retail store 419 , the garments are removed from the hangers and the hangers 411 are returned to the regional distribution center 417 . It is preferred that the hangers are shipped to the distribution center in collapsible pallet-sized boxes with plastic lids. While it is preferable to return all of the hangers to the regional distribution center 417 , it is noted that in actual practice, from 10-25% of the hangers shipped from the distribution center to the retail store as garments on hangers 421 are not returned, but are sold with the garment to the consumer, or are damaged or otherwise lost in use. At the regional distribution center 417 , the hangers are batched and sent to the recycle center 423 , again preferably in the collapsible pallet-sized boxes, where the removable size indicia are removed, and the hangers are inspected and sorted by size and type, and then cleaned. In a preferred embodiment of the invention, the size indicia are automatically removed as previously described with respect to FIGS. 7 and 8. At the recycle center 423 it has been found that from 10-30% of the hangers returned are no longer suitable for reuse because of excess wear, breakage, warpage, gum tags or other debris which can not easily be removed. The hangers that fail the inspection and the index caps are returned via distribution channel 425 to a location which grinds or granulates the hanger rejects and index caps as illustrated at 427 . At location 427 , the hangers are also separated to classify the hangers according to the material from which they were molded, with polypropylene and polystyrene being the two primary materials from which hangers are molded. The polypropylene granulated material is then used to mold consumer hangers as indicated at 429 which may be returned by a distribution channel 431 for sale to consumers. The remaining material not suitable for remolding is sold as scrap as indicated at 433 . At the recycle center 423 , it has been found that from 30-50% of the hangers that originally entered the recycling loop at 403 are available for redistribution. The hangers 411 , without any size indicia matter thereon, are then reshipped to the garment suppliers 405 as part of the order fulfillment at supply line 435 . The supply of hangers at 435 is augmented by freshly molded hangers as indicated at 403 and the combined stream of recycled and new hangers 437 is returned to the garment suppliers 405 as indicated in FIG. 11 . It is contemplated that each hanger will pass through the loop 2 to 6 times before it becomes unrecoverable. The hangers shipped from the recycle center 423 for reuse can be shipped to either US or offshore garment manufacturers. However, since it is contemplated that only 50-80% of the originally molded hangers will be reused the supply may only be sufficient to meet the demands of the closer, in this instance, the US garment manufacturers. The cost of molding vs. shipping internationally must also be taken into consideration when dealing with offshore garment manufacturers. However, the higher shipping costs are often outweighed to meet a particular customer's demand in an offshore country. Simultaneously therewith, a new plurality of removable size indicia are molded at 407 and shipped via channel 409 to the garment manufacturers 405 to be reassembled with the hanger arriving from product stream 437 . At the present time, it has been found that the labor and material handling required to sort the removable size indicia at the recycle center 423 is more expensive then newly molding the removable size indicia at step 407 . Not only are the removable size indicia molded in a plurality of colors, but each of the colors may represent as many as ten different sizes as herein before previously described. In addition to the sorting, the removable size indicia must be inspected, and reassembled into a magazine or plurality of stacked caps suitable for automated assembly with the hangers and garments at the garment manufacturers 405 . Consequently, in the normal course of proceeding, the removable size indicia are ground at step 427 and sold as scrap at step 433 as indicated by channel 439 . However, it is possible for the size indicia to be sorted at the recycle center 423 and then shipped back to the garment manufacturers for reuse. Presently, a significant percentage of garments sold in the retail stores 419 are manufactured off shore in areas such as China, Thailand, India, Ceylon, Turkey and countries of the Near East. These offshore garment manufacturers are indicated at 441 and provide essentially the same function as the domestic manufacturers indicated at 405 inasmuch as each of these entities manufactures a garment, and then assembles a hanger 411 , an index cap from the bundled stack 413 and the garment in an automated production line to form a product known as G.O.H. (Garment On Hanger) which is ready for display in the retail stores 419 . The G.O.H. garments are then batched as indicated at 443 and shipped via international transport, in generally intermodal or airborne containers, to the regional distribution center 417 . Inasmuch as the hangers, when molded represent a substantial bulk, it is upon occasion, less expensive to mold the hangers offshore as illustrated at 445 and ship the hangers 411 to a regional hanger distribution center 447 , than to mold and ship from the US facility 401 . Regional hanger distribution centers 447 may be located in such diverse geographic locales as Hong Kong, India or Turkey and intended to serve clusters of manufacturing entities located within a few hundred miles of the regional distribution center. Batches or bundles of removable size indicia 413 are also molded at 407 and shipped via distribution channels 409 , 449 and 451 to the offshore distribution centers 447 or offshore garment manufacturers 441 . The offshore distribution center 447 then makes separate shipments of hangers 411 and bundles of removable size indicia 413 to the offshore garment manufacturers 441 . The offshore garment manufacturer then assembles one of the hangers, one of the removable size indicia and one of the garments to provide a garment on hanger (G.O.H.) wherein the removable size indicia corresponds to the size of the garment. Molding the removable size indicia at a single location such as that indicated at 407 ensures that the colors chosen for the removable size indicia are consistent when they arrive at the retail stores 419 even though the adjacent garments and hangers may have been assembled thousands of miles apart from each other. In addition, the bulk and size of the bundles removable size indicia 413 render them susceptible to transoceanic shipment and use. While in the preferred embodiment, the removable size indicia are all molded in a single location, it would be entirely possible to mold the removable size indicia in one or more offshore molding facilities, provided precise control is maintained over the pigments used in the color indexing scheme. There may also be a flow of returned surplus hangers as indicated along distribution channel 450 and 450 a which may be used to augment the supply of hangers at 435 instead of molding new hangers at 401 . In the preferred embodiment, the hanger of the present invention is formed from styrene, K resin, H.I. styrene, polypropylene, other suitable thermoplastic or combinations thereof. The indicator of the present invention is formed from styrene or any other suitable plastic material. While there have been shown and described what are considered to be the preferred embodiments of the invention, it will, of course, be understood that various modifications and changes in form or detail can be readily made without departing from the spirit of the invention. It is therefore intended that the invention not be limited to the exact form and detail herein shown and described nor to anything less than the whole of the invention herein disclosed as hereinafter claimed.

4y

This invention relates to an apparatus and control method for regulating the engagement of a fluid operated automotive torque transmitting device, and more particularly, to an electronic flow control of fluid supplied to the device. BACKGROUND OF THE INVENTION In motor vehicle multispeed ratio automatic transmissions, it is often desirable to shift from one speed ratio to another without the use of freewheeling or one-way devices. This requires a coordinated timing control of both off-going and on-coming fluid operated torque transmitting devices in order to achieve a desired amount of overlap as the transmitted torque is shifted from the off-going device to the on-coming device. Typically, the pressure supplied to the off-going device is progressively released through an orifice, while fluid pressure is supplied to the on-coming device through an accumulator or a servo in which an output element is displaced (stroked) by the supplied pressure. Where a control of the on-coming device engagement time is desired, the fluid flow at the inlet or outlet of the accumulator or servo may be separately regulated. In one known system involving a servo actuated friction band device, for example, a speed-biased regulator valve is used to vary a restriction for fluid being displaced by the servo piston. In another similar system, an electrohydraulic valve is pulse-width-modulated at a variable duty cycle to vary a restriction at the fluid inlet of the servo. Unfortunately, these systems are relatively expensive to implement and often exhibit some level of supply pressure sensitivity, degrading the ability of the control to achieve the desired on-coming engagement time. SUMMARY OF THE PRESENT INVENTION The present invention is directed to an improved electronic control apparatus and method for regulating the engagement or stroke time of a fluid operated torque transmitting device, wherein the flow of fluid to the device is regulated with a flow control valve having a low flow state and a high flow state. The shift is initiated with the flow control valve in the high flow state. After a variable delay time, the flow control valve is activated to the low flow state to complete the shift. A relatively short delay time will decrease the average flow rate during the shift to increase the stroke time, while a relatively long delay time will increase the average flow rate during the shift to decrease the stroke time. The delay time is scheduled as an open-loop function of various system parameters to achieve the optimum amount of overlap between the on-coming and off-going torque transmitting devices. An adaptive learning control superimposed on the open-loop control trims the open-loop schedule to compensate for changes in system parameters or part-to-part tolerance variations which affect the stroke time. The digital or on-off nature of the flow control device avoids the expense of precision regulator or PWM valves The supply or line pressure sensitivity is drastically reduced because of the adaptive learning control, and because the delay time can be scheduled as a function of the same variables which determine line pressure. In the illustrated embodiment, the apparatus of this invention is mechanized in connection with a wash-out type shift control arrangement substantially as set forth in U.S. Pat. No. 2,865,227 to Kelley et al., issued Dec. 23, 1958, and assigned to the assignee of the present invention. In that arrangement, the servo for an off-going band brake operates as an The flow control device of this invention operates when a subsequent clutch-to-band downshift is required by controlling the stroke time of the servo for engaging the on-coming band brake. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 depicts a control apparatus according to this invention, sectional views of various hydraulic transmission control elements, including the flow control valve, and a computer-based control unit for carrying out line pressure and shift controls. FIG. 2 graphically depicts the ranges of servo stroke time which can be achieved by each state of the flow control valve of FIG. 1. FIG. 3 depicts a representative 3-D look-up table for scheduling the flow control valve delay tim as a function of vehicle speed and engine throttle position. FIG. 4, Graphs A-E, graphically depict various parameters during the course of a 3-2 clutch-to-band downshift according to this invention. FIGS. 5 and 6a-6b depict flow diagrams representative of computer program instructions executed by the computer-based control unit of FIG. 1 in carrying out the control of this invention. DETAILED DESCRIPTION OF THE INVENTION Referring particularly to FIG. 1, the reference numeral 10 generally designates an array of hydraulic transmission control elements for regulating the engagement and disengagement of friction clutch 12 and band brake 14 to effect shifting between a pair of forward transmission speed ratios. In a typical application, a 1:1 or direct ratio (3rd) is provided with engagement of the clutch 12, and an underdrive ratio (2nd) is provided with engagement of the band brake 14. Thus, a 2-3 upshift is achieved through concurrent disengagement of band brake 14 and engagement clutch 12, while a 3-2 downshift is achieved through concurrent disengagement of clutch 12 and engagement band brake 14. As explained below, this invention concerns the engagement of band brake 14 to effect a 3-2 downshift. The illustrated hydraulic elements include a positive displacement mechanically driven hydraulic pump 16, a pressure regulator valve 18, a force motor controlled line pressure bias valve 20 and limit valve 22, an operator manipulated manual valve 24, a solenoid controlled 2-3 shift valve 26, a clutch apply servo 28, a fluid restriction circuit 30, and a band apply servo 32. The pump 16 receives hydraulic fluid at low pressure from the fluid reservoir 40, and supplies line pressure fluid to the transmission control elements via output line 42. Pressure regulator valve 18 is connected to the pump output line 42 and serves to regulate the line pressure and torque converter feed pressure (CF) by returning a controlled portion of the line pressure to reservoir 40 via the line 44. The pressure regulator valve 18 is biased at one end by orificed line pressure in line 46 and at the other end by the combination of a spring 48 and a controlled bias pressure in line 50. The controlled bias pressure is supplied by the line pressure bias valve 20 which develops pressure in relation to the current supplied to electric force motor 52, the force motor 52 being hydraulically balanced by the pressure in bias chamber 54. Line pressure is supplied as an input to bias valve 20 via line 54 and the limit valve 22. An accumulator 56 connected to the bias pressure line 50 serves to stabilize the bias pressure. With the above-described valving arrangement, it will be seen that the line pressure of the transmission is electrically regulated by force motor 52. In the event of an interruption of electrical power to the force motor 52, the bias pressure in line 50 assumes a maximum value, thereby forcing maximum line pressure. The friction clutch 12 and band brake 14 are activated by conventional fluid servos 28 and 32, respectively. The servos 28 and 32, in turn, are connected to a fluid supply system comprising the manual valve 24, the 2-3 shift valve 26, and the fluid restriction circuit 30. The manual valve 24 develops a supply pressure D32 for the 2nd and 3rd forward speed ranges of the transmission in response to driver positioning of the transmission range selector lever 60. The D32 pressure, in turn, is supplied via line 62 to the shift valve 26 and fluid restriction circuit 30 for application to the servos 28 and 32. The shift valve 26 is spring-biased against a controlled bias pressure developed by the solenoid 64, the valve 26 being illustrated in its activated state. In the illustrated state, the shift valve 26 supplies D32 supply pressure to the clutch servo 28 via line 66 and to a release chamber 68 of band brake servo 32 via line 70. In the deactivated state, the lines 66 and 70 are exhausted via exhaust port 72. The fluid restriction circuit 30 comprises a first orifice 80 connecting the D32 supply pressure line 62 to an apply chamber 82 of band brake servo 32, and a solenoid operated flow control valve 84. The flow control valve 84 is selectively controlled to connect a second orifice in parallel with the first orifice 80, the second orifice being defined by the valve seat 86. The flow control valve 84 includes a pintle armature 88 which is normally retracted from the seat/orifice 86 by a return spring (not shown) to connect the second orifice in parallel with the first orifice 80, and a solenoid 90 which when electrically activated (energized) extends the pintle armature 88 into engagement with the seat/orifice 86. Thus, fluid pressure is supplied to the servo inlet chamber 82 via the parallel combination of orifices 80 and 86 when solenoid 90 is deactivated, and via the orifice 80 alone when solenoid 90 is activated. The deactivated condition thereby defines a high flow state, while the activated condition defines a low flow state. As described below, the valve 84 is controlled to its high flow state at the initiation of a 3-2 downshift, and is controlled to its low flow state after a determined delay time Td. The servo 32 includes a post 92 fastened to a diaphragm 94 which is axially displaceable within the servo housing. A pair of springs 96 and 98 reacting against the housing of servo 32 urge the diaphragm 94 and hence the post 92 downward, as viewed in FIG. 1, to release the band brake 14. The spring forces may be aided by fluid pressure in release chamber 68 or opposed by fluid pressure in apply chamber 82. Reference numeral 100 designates a computer-based control unit which develops suitable electrical control signals for the force motor 52 and the solenoids 64 and 90 in response to a variety of vehicle and powertrain parameters, represented by the input lines 102. The line pressure control of force motor 52 is essentially continuous during operation of the transmission, ensuring that the developed pressure is sufficient to prevent clutch slippage during steady state operation, and providing shift quality control during shifting. The control of solenoids 64 and 90, on the other hand, pertain strictly to shifting and are discrete or on-off in nature. In 2nd ratio operation, the shift valve solenoid 64 is deactivated so that the clutch servo 28 and the band brake servo release chamber 68 are vented through shift valve exhaust port 72. The servo apply chamber 82 is maintained at D32 supply pressure via fluid restriction circuit 30, overcoming the spring bias to extend the servo post 92 and engage the band brake 14. When a 2-3 upshift is required, the control unit 100 activates the shift valve solenoid 64 to connect the D32 supply pressure to clutch servo 28 and the release chamber 68 of band brake servo 32 via orifice 29. This pressure balances the apply chamber pressure, allowing the springs 96 and 98 to stroke the diaphragm 94, retracting the post 92 as the apply chamber fluid is displaced through the fluid restriction circuit 30 and into the pressure control line 62. During this operation, the solenoid 90 is deactivated, and the flow control valve 84 is in its high flow state. The pressure in the clutch servo 28 builds as a function of the spring rates and orifices, engaging the clutch 12 as the band brake is released. This is a conventional band-to-clutch wash-out upshift. When a 3-2 downshift is required, the control unit 100 determines a delay time Td for the flow control valve 84, and deactivates the shift valve solenoid 64 to vent the fluid in clutch servo 28 and band brake servo release chamber 68. The determination of delay time Td is described below in reference to FIG. 3. The combination of the line pressure (D32) and the effective orifice size of fluid restriction circuit 30 determines the fluid flow rate into servo apply chamber 82, which in turn, determines the stroke time of the servo post 92. Once the shift is complete, there is no flow through the fluid restriction circuit 30, and the solenoid 90 is deactivated. The graph of FIG. 2 illustrates the relationship between the stroke time of band brake servo 32 and the transmission line pressure, with and without activation of the flow control valve solenoid 90. When the solenoid 90 is activated and the supply pressure can only pass through orifice 80, the relationship is given by the "1 ORIFICE" trace 110. As one would expect, increasing line pressure increases the fluid flow, thereby decreasing the stroke time; similarly, decreasing line pressure decreases the fluid flow, thereby increasing the stroke time. When the shuttle valve solenoid 90 is deactivated and the supply pressure can pass through the valve seat orifice 86 as well as the orifice 80, the relationship is given by the "2 ORIFICE" trace 112. The parallel combination of orifices 86 and 80 permits increased flow, resulting in reduced stroke time for a given line pressure. The graph of FIG. 2 also shows that the range of available stroke times depends on the transmission line pressure. At pressure Pl, for example, the shortest stroke time Tmin is achieved by maintaining the high flow (two orifice) state throughout the shift, while the longest stroke time Tmax is achieved by maintaining the low flow (one orifice) state throughout the shift. Stroke times between Tmin and Tmax are obtained, according to this invention, by initiating the shift in the high flow state and switching to the low flow state after a determined delay time Td. Of course, a zero delay time would result in a stroke time of Tmin, and a long delay time would result in a stroke time of Tmax. As the line pressure increases above Pl, both Tmin and Tmax decrease; as the line pressure decreases below Pl, both Tmin and Tmax increase Since the same considerations which generally dictate an increase in stroke time dictate a decrease in line pressure, and vice versa, the range of available stroke times (Tmax-Tmin) is generally adequate to achieve optimum shift timing control. The primary control parameters for both line pressure and stroke time are vehicle speed and transmission input torque, as typically represented by engine throttle position. As the vehicle speed increases, it is generally advantageous to decrease line pressure to reduce spin losses, and to increase the downshift stroke time so that the input speed can substantially reach the 2nd ratio speed by the time the band brake 14 engages. As the input torque increases, it is generally advantageous to increase the line pressure to prevent steady state clutch slippage, and to decrease the downshift stroke time to limit the energy absorbed by the on-coming band brake. The above considerations, at least with respect to stroke time, are reflected in the 3-D look-up table representation of FIG. 3. Thus, for a given engine throttle position, the desired delay time Td decreases with increasing vehicle speed to provide increasing servo stroke time. For a given vehicle speed, the desired delay time Td increases with increasing engine throttle position to provide decreasing servo stroke time. In the above described mechanization, it is most convenient to address the effects of line pressure variations by empirically determining and storing delay time values into the look-up table of FIG. 3. That is, the delay time values which are empirically found to achieve the desired stroke times in various operating conditions of the powertrain are stored in a look-up table or data array as a function of the corresponding engine throttle position vs. vehicle speed test points. Delay times for engine throttle position vs. vehicle speed operating points between empirically determined values are determined by interpolation. Factors compensating for the effects of temperature and altitude variations may also be taken into account. In the preferred embodiment of this invention, a second look-up table or data array is provided for the storage of adaptive corrections to the table depicted in FIG. 3. As explained below in connection with FIGS. 4 and 6b, the performance of the transmission control in the course of normal 3-2 downshifts is measured and compared to a reference indicative of high quality shifting. If the measured value significantly deviates from the reference value, the control unit develops or updates a delay time adaptive correction term Td(adapt) for the operating point in effect during the shift. In the next 3-2 downshift at such operating point occurs, the delay time will be determined as a combined function of the base delay time Td(base) from the table of FIG. 3 and the adaptive correction term Td(adapt) from the adaptive table, so that the shift quality will be improved. A 3-2 downshift according to this invention is depicted in Graphs A-E of FIG. 4 on a common time base. Graph A depicts the transmission speed ratio Nt/No; Graph B depicts the torque capacity of the 3rd clutch 12; Graph C depicts the stroke or displacement of servo 32; Graph D depicts the torque capacity of the 2d band brake 14; and Graph E depicts the energization state of the flow control valve solenoid 90. Initially, the shift valve solenoid 64 is energized to engage 3rd clutch 12, and the flow control valve solenoid 90 is deenergized, defining a high flow state. The shift is initiated at time t0 with the deenergization of shift valve solenoid 64 and the determination by control unit 100 of a flow control valve delay time Td. The deenergization of shift valve solenoid 64 quickly reduces the torque capacity of 3rd clutch 12, as indicated in Graph B. Shortly thereafter at time t1, the input speed, and therefore the ratio Nt/No, increases toward the 2nd ratio, as indicated in Graph A. The control unit 100 detects the change in speed ratio Nt/No as indicated in Graph E, and starts a delay timer for comparison with the determined delay time Td. Also, approximately at time t1, the flow of fluid through orifices 80 and 86 begins to stroke the servo post 92, as indicated in Graph C. This displaces the fluid in servo release chamber 68 into the 3rd clutch exhaust circuit, slowing the release of 3rd clutch 12, as indicated in Graph B. In view of the above, it will be recognized that conditions other than a change in the speed ratio Nt/No may be used to initiate the measured delay time. For example, the delay time could be initiated in response to a detected initial displacement of the servo post 92, or the deenergization of shift valve 64. At time t2, the delay timer count reaches the determined delay time Td, and the control unit 100 energizes the flow control valve solenoid 90 as indicated in Graph E. This closes the orifice 86, decreasing the flow to servo apply chamber 82, and reduces the rate of displacement of servo post 92, as indicated in Graph C. At time t3 when the servo 32 is almost fully stroked, the torque capacity of 2nd band brake 14 quickly increases, as indicated in Graph D. When the fully stroked position is reached at time t4, the remaining fluid pressure in 3rd clutch servo 28 quickly exhausts through orifice 72, fully releasing the 3rd clutch 12, as indicated in Graph B. At this point, the ratio change is completed, as indicted in Graph A. Shortly thereafter at time t5, the flow control valve solenoid 90 is deenergized in preparation for the next shift. As indicated in reference to FIG. 3, the above-described control is carried out essentially open-loop in that a predetermined delay time is used to control the operation of flow control valve 84 during the course of a shift. However, it is recognized that it may be desirable to trim the empirically determined delay times to compensate for part-to-part tolerance variations and other variations which occur over time. The control unit 100 continues to monitor specified parameters in the course of the shift to detect an aberration which indicates an inappropriate delay time Td. One such indication is engine flare, as indicated by the broken line 114 in Graph A of FIG. 3. This condition occurs if the stroke time is too long. If this condition is detected, the solenoid 90 is immediately deenergized to return the flow control valve 84 to the high flow state, and an adaptive delay term Td(adapt) for increasing the delay time is determined and stored in the adaptive table referenced above in relation to FIG. 3. A further indication of a delay time aberration is the shift time. This condition occurs if the stroke time is too short, as indicated by the broken line 116 in Graph A of FIG. 3. This condition is detected by comparing a measure of the shift time to a reference shift time STref based on vehicle speed Nv. If the measured shift time is significantly shorter than the reference shift time, an adaptive delay term Td(adapt) for decreasing the delay time is determined and stored in the adaptive table. Flow diagrams representative of computer program instructions for carrying out the control of this invention with the apparatus of FIG. 1 are depicted in FIGS. 5 and 6a-6b. The flow diagram of FIG. 5 represents a main or executive computer program which is periodically executed in the course of vehicle operation in carrying out the control of this invention. The block 230 designates a series of program instructions executed at the initiation of each period of vehicle operation for setting various terms and timer values to an initial condition. Thereafter, the blocks 232-234 are executed to read the various inputs referenced in FIG. 1 and to determine the desired speed ratio Rdes. The desired ratio Rdes may be determined in a conventional manner as a predefined function of engine throttle position TPS and output vehicle speed Nv. If the actual ratio Ract--that is, No/Nt--is equal to the desired ratio Rdes, as determined at block 238, the blocks 243 and 244 are executed to deenergize the flow control valve solenoid 90 and to determine the desired line pressure LPdes. In this case, the desired line pressure LPdes is determined as a function of throttle position and output speed, and also is adjusted based on the desired ratio Rdes and an adaptive corrective term Pad. The adaptive correction term Pad may be generated during upshifting, based on shift time, as set forth in U.S. Pat. No. 4,283,970 to Vukovich et al. issued Aug. 18, 1981, and assigned to the assignee of this invention. If an upshift is required, as determined by blocks 238 and 240, the blocks 242 and 244 are executed to perform suitable Upshift Logic in addition to determining the desired line pressure LPdes as described above. If a downshift is required, as determined by blocks 238 and 240, the blocks 246 and 248 are executed to determine the desired line pressure LPdes and to perform the Downshift Logic. In this case, the desired line pressure is determined as a function of throttle position, output speed, the pre-shift or old ratio Rold, and the adaptive correction term Pad, as indicated at block 246. As indicated at block 248, the Downshift Logic is set forth in further detail in the flow diagram of FIGS. 6a-6b. In any case, the block 250 is then executed to convert the desired line pressure LPdes to a solenoid duty cycle LP(dc), to output the duty cycle LP(dc) to force motor 52, and to output discrete solenoid states to the solenoids 64 and 90. Referring now to the Downshift Logic flow diagram of FIGS. 6a-6b, the block 252 is first executed to determine the required states of the various shift valve solenoids. As indicated above, the present invention concerns the 2-3 shift valve solenoid 64, which is activated to initiate a 2-3 upshift and deactivated to initiate a 3-2 downshift. If the shift is a 3-2 downshift, as detected at block 254, the blocks 256-274 are executed to determine the required state of flow control valve solenoid 90 as a function of the vehicle speed Nv and engine throttle position TPS, as described above in reference to FIGS. 3-4. When the transmission speed ratio Nt/No first starts to increase toward 2nd, as determined by blocks 256-258, the blocks 260-262 are executed to look up the delay time Td as a function of measured vehicle speed and engine throttle position values Nv, TPS, to look up a reference shift time STref as a function of the vehicle speed Nv, and to reset the DELAY TIMER. As indicated at block 260, the delay time Td is comprised of two components: a base delay time Td(base) and an adaptive delay time Td(adapt). Thereafter during the shift, execution of the blocks 260-262 is skipped, as indicated by the flow diagram line 263. Until the DELAY TIMER reaches the determined delay time Td, or unless engine flare is observed, as determined by blocks 264 and 270, the remainder of the routine is skipped. Once the DELAY TIMER reaches the determined delay time Td, the block 266 is executed to energize the flow control valve solenoid 90. The adaptive delay time functions are set forth in FIG. 6b, which is a continuation of the flow diagram of FIG. 6a. If engine flare is observed, by detecting an unexpected increase in the ratio Nt/No, for example, the blocks 272-274 are executed to deenergize the flow control solenoid 90 and to increment or update the adaptive delay time value Td(adapt) for the vehicle speed vs. engine throttle position operating point used at block 260. The amount of the increase may be fixed or variable as a function of the amount or timing of the observed flare. If the ratio change is almost complete and the DELAY TIMER is significantly less than the the reference shift time value STref, as determined at blocks 276-278, the block 280 is executed to decrement or update the adaptive delay time value Td(adapt) for the vehicle speed vs. engine throttle position operating point used at block 260. As with the adaptive increase of Td(adapt), the amount of the adaptive decrease may be fixed or variable as a function of the deviation of the actual shift time (DELAY TIMER) from the reference shift time STref. While illustrated in reference to a wash-out shift arrangement, it will be appreciated that the engagement rate control of the present invention will find application in the engagement of any torque transmitting device having a member which is displaced by a servo in relation to the volume of fluid directed to an apply chamber thereof. It is expected that various other modifications to the illustrated embodiment will occur to those skilled in the art as well, and it should be understood that controls incorporating such modifications may fall within the scope of the present invention, which is defined by the appended claims.

4y

CROSS-REFERENCE TO RELATED APPLICATION [0001] The present application is a continuation-in-part of U.S. application Ser. No. 09/981,801 filed Oct. 19, 2001, which in turn is a continuation-in-part of U.S. application Ser. No. 09/776,929 filed Feb. 6, 2001, now abandoned. BACKGROUND OF THE INVENTION [0002] 1. Field of the Invention [0003] The present invention relates to improvements in key and key blank configurations for use with twisting tumbler/sidebar-slider controlled cylinder locks of the type disclosed in the parent applications, and a master keying system therefor. [0004] 2. Description of the Background Art [0005] Keys to operate locks with rotating reciprocating (twisting) tumblers are conventionally bitted on the upper portion of the key blade with skew cut bittings. The skew cuts operate in combination with chisel pointed spring loaded tumbler pins to position the pins at the correct location to operate the cylinder. This type of lock is known as a Medeco lock made by Medeco Security Locks, Inc. of Salem, Va. Medeco cylinders of this type are well-known and their construction and operation is disclosed, for example, in U.S. Pat. Nos. 3,499,302 (Spain et al.) and U.S. Pat. No. 3,722,240 (Spain et al.). Other and later patents, for example, describing the Medeco locks are U.S. Pat. No. 4,635,455 (Oliver), U.S. Pat. No. 4,732,022 (Oliver), U.S. Pat. No. 5,289,709 (Field), U.S. Pat. No. 5,419,168 (Field) and U.S. Pat. No. 5,570,601 (Field). [0006] The first generation of twisting tumbler locks, for example, rotating pin tumblers with skew cut keys manufactured by Medeco Security Locks, Inc., utilized variations in the pins to establish a master keying system. This technique is well-known in the lock industry. [0007] The second generation of Medeco locks was sold under the trademark BIAXTAL and expanded on the master keying capabilities of the original Medeco products by off-setting the key bittings along the blade of the key and providing pins with different offset tips. This construction and technique is disclosed, for example, in U.S. Pat. Nos. 4,635,445 (Oliver) and 4,732,022 (Oliver). SUMMARY OF THE INVENTION [0008] The ability of a locksmith or lock manufacture to configure lock cylinders to operate in master keying systems is quite important in the lock industry. The present invention provides additional benefits in increased master keying which is primarily attributed to the uniquely formed key blank and key operating with a third level locking slider for the Medeco lock as disclosed in U.S. application Ser. No. 09/981,801, which is incorporated herein by reference. [0009] The key of the present invention has a conventional bitting area and, on the side of the key blade, a rib that projects horizontally from a longitudinal axis of the key. The rib of the present invention is provided with a front end to contact a slider that moves axially within the cylinder. By varying the structure, configuration and placement of the front end of the rib and the slider contact surface, a unique master keying system has been developed whereby each lock can be operated by its own key and groups of locks can be operated by a master key. In other words, new master keying systems are disclosed using a unique technique which requires a rib on the side of the key blank to interact with a uniquely configured sliding member in the cylinder. The sliding member functions to block the operation of the cylinder until the key correctly positions the slider as explained in U.S. application Ser. No. 09/981,801. [0010] U.S. application Ser. No. 09/981,801 discloses variations of the front end of the rib that contacts the slider whereby the front ends are slopped at an angle or stepped in a vertical plane. The present invention provides variations in the depths of the front end of the slider along a horizontal plane of the key. Further, the present invention improves on the invention of U.S. application Ser. No. 09/981,801 in that the structure of the fore end of the rib on the key and the structure of the mating contact area on the slider and the cylinder are configured so that there are spaced horizontal areas which can then be used to significantly increase the master keying capabilities. [0011] The above and other features and advantages of the present invention will be further understood from the following description of the preferred embodiments thereof, taken in conjunction with the accompanying drawings wherein like reference numerals are used throughout the various views to designate like parts. BRIEF DESCRIPTION OF THE DRAWINGS [0012] [0012]FIG. 1 a is a side elevation view of a key blank according to the present invention. [0013] [0013]FIG. 1 b is a sectional view taken along line A-A of the key blank of FIG. 1 a. [0014] [0014]FIG. 1 c is a bottom plan view of the key blank of FIG. 1 a. [0015] [0015]FIG. 2 a is a side elevation view of another configuration of a key blank according to the present invention. [0016] [0016]FIG. 2 b is a sectional view taken along line B-B of the key blank in FIG. 2 a. [0017] [0017]FIG. 2 c is a bottom plan view of the key blank of FIG. 2 a. [0018] [0018]FIG. 3 a is a side elevation view of yet another configuration of a key blank according to the present invention. [0019] [0019]FIG. 3 b is a sectional view taken along line C-C of the key blank of FIG. 3 a. [0020] [0020]FIG. 3 c is a bottom plan view of the key blank of FIG. 3 a. [0021] [0021]FIG. 4 a is a side elevation view of a key blank with a different configuration of contact surfaces on a slider contacting rib according to the present invention. [0022] [0022]FIG. 4 b is a sectional view taken along line D-D of the key blank of FIG. 4 a. [0023] [0023]FIG. 4 c is a bottom plan view of the key blank of FIG. 4 a. [0024] [0024]FIG. 5 a is a side elevation view of another key blank with a different configuration of contact surfaces on a slider contacting rib according to the present invention. [0025] [0025]FIG. 5 b is a sectional view taken along line E-E of the key blank of FIG. 5 a. [0026] [0026]FIG. 5 c is a bottom plan view of the key blank of FIG. 5 a. [0027] [0027]FIG. 6 a is a side elevation view of yet another key blank with a different configuration of contact surfaces on a slider contacting rib according to the present invention. [0028] [0028]FIG. 6 b is a sectional view taken along line F-F of the key blank of FIG. 6 a. [0029] [0029]FIG. 6 c is a bottom plan view of the key blank of FIG. 6 a. [0030] [0030]FIG. 7 is a bottom plan view of a slider illustrating one of the many possible key contact variations. [0031] [0031]FIG. 8 is a perspective view of the slider shown in FIG. 7. [0032] [0032]FIG. 9 is a perspective view of a slider similar to FIG. 8 but shown with a different configuration of key rib contact surfaces. [0033] [0033]FIG. 10 is a perspective view of a slider showing yet another configuration of key rib contact surfaces. [0034] [0034]FIG. 11 a is a side elevation view of a cylinder lock illustrating the operation of a properly configured key blank according to the present invention. [0035] [0035]FIG. 11 b is a sectional view taken along line G-G of the arrangement shown in FIG. 11 a. [0036] [0036]FIG. 11 c is a bottom plan view of the arrangement shown in FIG. 11 a. [0037] [0037]FIG. 12 a is a side elevation view of another cylinder lock illustrating the operation of a properly configured key blank according to the present invention. [0038] [0038]FIG. 12 b is a sectional view taken along line H-H of the arrangement shown in FIG. 12 a. [0039] [0039]FIG. 12 c is a bottom plan view of the arrangement shown in FIG. 12 a. [0040] [0040]FIG. 13 a is a side elevation view of a slider controlled lock illustrating the operation of an improperly configured key blank according to the present invention. [0041] [0041]FIG. 13 b is a sectional view taken along line I-I of the arrangement shown in FIG. 13 a. [0042] [0042]FIG. 13 c is a bottom plan view of the arrangement shown in FIG. 13 a. [0043] [0043]FIG. 14 a is a side elevation view of a further key blank according to the present invention with a particular surface rib contact. [0044] [0044]FIG. 14 b is a sectional view taken along line J-J of the key blank of FIG. 14 a. [0045] [0045]FIG. 14 c is a bottom plan view of the key blank of FIG. 14 a. [0046] [0046]FIG. 15 a illustrates a Medeco BIAXIAL® key incorporating the slider contact rib according to the present invention. [0047] [0047]FIG. 15 b is a sectional view taken along line K-K of the key of FIG. 15 a. [0048] [0048]FIG. 15 c is a bottom plan view of the key of FIG. 15 a. [0049] [0049]FIG. 16 a illustrates an original Medeco key incorporating the slider contact rib according to the present invention. [0050] [0050]FIG. 16 b is a sectional view taken along line L-L of the key of FIG. 16 a. [0051] [0051]FIG. 16 c is a bottom plan view of the key of FIG. 16 a. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS [0052] With reference to FIGS. 1 a - c , a key blank 10 is comprised of a key head or key bow 101 , a key blade portion 103 extending from the key bow 101 as is conventional, and a key stop 102 . The key stop 102 limits the insertion of a key into a lock cylinder plug. The key blade 103 is divided vertically into two areas, the top area is a skewed cut bitting area 104 and the bottom area is a slider contact rib area 105 . [0053] Variations in the key blank 10 are achieved in part by the length of a slider contact rib 106 . These variations are measured longitudinally from the key stop 102 to a fore end 107 of the slider contact rib 106 . On the key blank 10 , as illustrated in FIGS. 1 a - c , the fore end 107 of the slider contact rib 106 is positioned at predetermined location 1 . [0054] [0054]FIGS. 2 a - c show a similarly configured key blank 20 with a key stop 202 and a fore end 207 of a slider contact rib 206 which is positioned at predetermined location 2 . [0055] With reference to FIGS. 3 a - c , a key blank 30 similar to the key blanks described above has a key stop 302 and a slider contact rib 306 with a fore end 307 positioned at predetermined location 3 . [0056] [0056]FIGS. 4 a - c show a key blank 40 having a key stop 402 and a slider contact rib 406 . The slider contact rib 406 has two separate fore end portions: an inner part 407 and an outer part 408 . As can be seen, the inner part 407 of the fore end is positioned at predetermined location 1 while the outer part 408 of the fore end is positioned at predetermined location 6 . [0057] With regard to FIG. 5, a key blank 50 is of similar configuration having a key stop 502 and a slider contact rib 506 with an inner part 507 of a fore end positioned at predetermined location 2 and an outer part 508 of the fore end positioned at predetermined location 6 . [0058] Similarly, the key blank 60 illustrated in FIG. 6 has a key stop 602 . A fore end of a slider contact rib 606 has two portions: an inner part 607 and an outer part 608 . The inner part 607 of the fore end is positioned at predetermined location 3 and the outer part 608 of the fore end is positioned at predetermined location 6 . [0059] With reference to FIGS.14 a - c , a key blank 4000 has a key stop 4002 and a slider contact rib 4006 . The slider contact rib 4006 has two contact end portions 4007 and 4008 . The contact end portion 4007 is at a predetermined position 1 and the contact end portion 4008 is at a predetermined position 3 . [0060] A Medeco BIAXIAL® lock can be modified to utilize the slider contact rib on a key blank of the present invention. FIG. 15 a illustrates the Medeco BIAXIAL® key incorporating the slider contact rib on the side of the key. Referring to FIGS. 15 a - c , a key 5000 has a stop 5002 and a slider contact rib 5007 . [0061] An original Medeco cylinder lock can also be modified to utilize the slider contact rib on a key blank of the present invention. FIG. 16 a illustrates the original cylinder Medeco key incorporating the slider contact rib on the side of the key. Referring to FIGS. 16 a - c , a key 6000 has a stop 6002 and a slider contact rib 6007 . [0062] With regard to FIGS. 7 and 8, a slider 70 has at least one projection 707 on its top surface that must be precisely positioned before the lock cylinder can open, as explained in the above-referenced application. On the bottom edge of the slider 70 is a key contact rib 708 that contains contact areas that mate with a slider contact rib on a key. On the slider 70 , contact area 713 is configured to a predetermined location 3 so that the contact area 713 mates with a fore end of the slider contact rib on the key. The other contact area 721 is configured to a predetermined location 1 and has a contact surface to mate with a fore end of the slider contact rib on the key. [0063] [0063]FIG. 9 shows another embodiment of a slider 71 which has a slider body 709 and a key contact rib 708 ′ that contains contact areas 712 , 721 . The contact areas 712 , 721 mate with a slider contact rib on a key, and are configured to two predetermined locations. The contact area 712 closest to the slider body 709 is configured to predetermined location 2 for mating with a fore end of the slider contact rib on the key. The contact area 721 farthest from the slider body 709 is configured to predetermined location 1 for mating with a fore end of the slider contact rib on the key. [0064] With regard to FIG. 10, a further slider configuration is shown. A slider 72 contains contact areas 711 , 721 that mate with a slider contact rib on a key. Similarly, the contact areas 711 , 721 are configured to two predetermined locations. The contact area 711 closest to the slider body 709 is configured to predetermined location 1 for mating with the fore end of the slider contact rib on the key. The contact area 721 furthest away from the slider body 709 is also configured to predetermined location 1 for mating with a fore end of the slider contact rib on the key. [0065] The operation of the key for locking/unlocking a cylinder lock or locks with rotating reciprocating (twisting) tumblers will now be described with reference to FIGS. 11 - 13 . As illustrated in FIGS. 11 a - c , a lock cylinder plug 90 contains tumbler pin holes 91 to house Medeco-type chisel pointed rotatable tumbler pins (not shown). Contained within the lock cylinder plug 90 is a sidebar 80 with sidebar legs 81 as is known in the art of Medeco locks. The sidebar 80 has at least one notch 82 to receive the corresponding projection 707 on the slider 70 (FIGS. 7 - 10 ) when the key correctly positions the slider 70 . The slider 70 fits into a cavity 93 in the lock cylinder plug 90 and is biased by a spring (not shown) towards a face 92 of the lock cylinder plug 90 . When the key 30 , illustrated in FIGS. 3 a - c , for example, is inserted into the lock cylinder plug 90 , the contact area 713 on the slider 70 mates with the fore end 307 on the key to correctly position the slider 70 within the lock cylinder plug 90 . [0066] As illustrated in FIGS. 12 a - c , the lock cylinder plug 90 containing slider 70 can also be operated, for example, with the key 40 , as illustrated in FIGS. 4 a - c . The slider contact rib 406 on the key 40 is provided with the inner part 407 of the fore end and the outer part 408 of the fore end. The inner part 407 of the fore end is positioned at predetermined location 1 and the outer part 408 of the fore end is positioned at predetermined location 6 . The inner part 407 of the fore end mates with the contact area 721 on the slider 70 and positions the slider 70 in a correct operating location. The outer part 408 of the fore end is sufficiently clear of the contact area 713 on the slider 70 and does not mate with the contact area 713 . [0067] As illustrated in FIGS. 13 a - c , the lock cylinder plug 90 containing slider 70 cannot be operated, for example, with the key 20 (FIGS. 2 a - c ). The fore end 207 of the slider contact rib 206 is positioned at predetermined location 2 . When the key 20 is inserted into the lock cylinder plug 90 , the key contact rib 713 on the slider 70 mates with the fore end 207 of the slider contact rib 206 . The slider 70 moves so far away from the face 92 of the lock cylinder plug 90 that the projection 707 will not fit within the notch 82 on the sidebar 80 . [0068] When a key with the unique slider contact rib as disclosed herein is inserted into a lock cylinder plug containing the unique slider described in the aforementioned application, the first contact surface on the slider contact rib to mate with the key contact surface on the slider will position the slider in the lock cylinder plug. However, if the key 4000 (FIGS. 14 a - c ), for example, is used in a lock cylinder containing the slider 70 , both surfaces 4007 , 4008 will mate with contact areas 712 , 721 simultaneously, and thus, both surfaces 4007 , 4008 will position the slider 70 . [0069] By positioning the slider contact rib on the key blank to six predetermined locations and dividing the slider contact rib into two horizontal contact surfaces, it is possible to configure 21 (twenty one) different key blanks to fit into one keyway of a cylinder lock. [0070] A key blank could be configured into any one of the following 21 possibilities by identifying the inner part or innermost horizontal contact surface as 1 a , 2 a , 3 a , 4 a , 5 a and 6 a , and the outer part or outermost horizontal contact surface as 1 b , 2 b , 3 b , 4 b , 5 b and 6 b: [0071] [0071] 1 b - 1 a [0072] [0072] 2 b - 1 a [0073] [0073] 2 b - 2 a [0074] [0074] 3 b - 1 a [0075] [0075] 3 b - 2 a [0076] [0076] 3 b - 3 a [0077] [0077] 4 b - 1 a [0078] [0078] 4 b - 2 a [0079] [0079] 4 b - 3 a [0080] [0080] 4 b - 4 a [0081] [0081] 5 b - 1 a [0082] [0082] 5 b - 2 a [0083] [0083] 5 b - 3 a [0084] [0084] 5 b - 4 a [0085] [0085] 5 b - 5 a [0086] [0086] 6 b - 1 a [0087] [0087] 6 b - 2 a [0088] [0088] 6 b - 3 a [0089] [0089] 6 b - 4 a [0090] [0090] 6 b - 5 a [0091] [0091] 6 b - 6 a [0092] Similarly, sliders of cylinder locks can be configured into the same 21 different arrangements. [0093] A lock containing a 3 b - 1 a slider can be operated by keys with the following configurations: [0094] [0094] 3 b - 1 a [0095] [0095] 3 b - 2 a [0096] [0096] 3 b - 3 a [0097] [0097] 4 b - 1 a [0098] [0098] 5 b - 1 a [0099] [0099] 6 b - 1 a [0100] With the above key blank and slider configurations, and the existing Medeco master keying techniques, a much larger and more complex master keying system can be provided than that previously known and available. [0101] Although the present invention has been described with reference to the particular embodiments disclosed, it is understood that these embodiments are merely illustrative of the application and principles of the invention. Numerous other configurations can be made and other arrangements can be devised without departing from the spirit and scope of the invention as defined in the appended claims.

4y

FIELD OF THE INVENTION The present invention relates to systems for the transmission and display of information, in particular time-related information, as well as for the control, monitoring and reporting of equipment, processes and other activities using the transmitted and/or displayed information. BACKGROUND OF THE INVENTION U.S. Pat. No. 1,871,636 issued Aug. 16, 1932 describes a system which uses carrier signals imposed on electrical power service lines to provide a plurality of subscribers connected to the service line with an audible chime synchronized with that actually produced by a central, reference chiming clock. The chime of the central, reference clock is picked up by an adjacent microphone, transmitted as a carrier signal over the power service lines and received in the subscriber's location where the chime sound is emitted through a speaker in the subscriber's clock connected to the service line. U.S. Pat. No. 2,020,039 issued Nov. 5, 1935 describes an electrical signalling system in which two cyclic variable frequency oscillators generate variable frequency outputs of widely different amplitudes from rotors driven at different speeds by the hands of a master clock. The two outputs are transmitted by radio or wire to an amplifier type receiver to which a vibrating reed-time display device is connected. As is apparent, the patented system uses varying frequencies for time code. U.S. Pat. No. 2,188,145 uses three different groups of frequencies which can be transmitted by radio channel and wire channel, including power, telephone and telegraph wires, to a time display receiver which may comprise a radio receiver and time indicator with vibrating reed elements. This patented system for transmitting and displaying time information is similar to that disclosed in U.S. Pat. No. 2,020,039 discussed in the preceding paragraph. U.S. Pat. No. 2,671,131 issued Mar. 2, 1954 discloses a television system for remote time indication. In the system, a television transmitter transmits the image of a master clock through a separate television channel to a special television receiver and display. Finally, U.S. Pat. No. 4,204,398 issued May 27, 1980 describes a system for automatically causing a change in the time displayed by a remote timepiece to bring the time thereof into confirmity with the local time zone. The remote timepiece internally generates a time coded signal representing its individual time computation which signal is in the same language as a transmitted time code reference signal. Periodically, the signals are compared, and if different, the timepiece circuitry itself makes appropriate adjustment to achieve confirmity with the reference. The coded reference signal is transmitted by a short wave transmitter (radio or ultrasonic) modulated with the coded time signal. The timepiece includes a microminiature electronic circuit with a short wave radio or ultrasonic receiver for receiving the transmitted time standard signal. SUMMARY OF THE INVENTION The present invention has an object the provision of a novel system for providing a facility with useful time or other information for direct display or for control or monitoring of equipment, activities and the like within the facility. The invention also has as an object the provision of such a system which can also report on the status and operation of equipment, activities and the like within a facility. The invention has as another object the provision of such a system which utilizes existing electrical gridwork or circuitry within the facility to achieve such information transmission, display, control, monitoring, and reporting. The invention has as still another object the provision of such a system which can utilize time or other information generated from a standard source either remote or within the facility serviced by the system. The invention has as another object the provision of such a system which can replace timing devices, control devices and monitoring devices heretofore used in facilities such as homes, multi-family dwellings, office buildings, factories, mobile vehicles, and the like. In a typical working embodiment of the invention, the system includes a source of information signals in coded form for transmission. For example, the source of information could be a reference time source located remote or within the facility with a code-generating means, if necessary, to provide the desired coded signal. In particular, the information source could be the so-called Coordinated Universal Time signal transmitted by about thirty radio stations throughout the world based on Greenwich Mean Time in conjunction with a code generating means (formatter) either remote from or within the facility. Or, the information source could be a master clock or other timepiece within the facility in conjunction with a Formatter also within the facility. Furthermore, known sensing and signal-generating devices for pressure, temperature, volume, velocity, density, flow, chemical composition, electrical frequency, voltage or current and other senseable parameters may be used as the information source in conjunction with a code-generating means (formatter). The system, in addition to the source of coded information signals, includes means for receiving coded information signals from the source, wherever located, and for transmitting the coded signals on the facility's electrical gridwork, preferably on the neutral leg of the electrical, not fused, gridwork, for distribution to outlet receptacles and switches simultaneously with the electrical A.C. power associated with the facility. The system also includes time or signal employing means such as appropriate time or parameter display devices, timing devices, and time or parameter-controlled devices connected to the facility's outlet receptacles, switches and the like and which can use the coded signals. The signal receiving and transmitting means may also include, if desired, programming means for controlling the time employing means in a preselected or adoptive fashion or sequence. The above recited object, features, and advantages of the present invention as well as others will be explained in greater detail hereinbelow with reference to the accompanying drawings. BRIEF DESCRIPTION OF DRAWINGS FIG. 1 is a schematic illustration of the system for distributing time information signals to a facility with multiple signal-interpreting means. FIG. 2 is a similar to FIG. 1 with the addition of programming means to the system. FIG. 3 is a schematic illustration of the system for distributing time information signals from a Coordinated Universal Time source to a facility. FIG. 4 is a schematic illustration of the system for distributing time information signals from a Coordinated Universal Time source via an intermediate utility station to a facility. FIG. 5 is a schematic illustration of the system where time employing devices are used with monitoring means. DESCRIPTION OF PREFERRED EMBODIMENTS FIG. 1 illustrates in schematic form a typical system of the invention for distributing coded time signals throughout a facility having an electrical service 2 of conventional design, for example, electrical service constructed in accordance with the National Electric Code having a neutral or grounded leg which cannot be interrupted. The electrical service, of course, includes a number of outlet receptacles 4 for making electrical A.C. power available for use. The system is shown including a clock 10 to provide a source of accurate time signals. The clock can be of conventional construction provided with an electrical signal means for producing code representing time and in the embodiment shown in FIG. 1 may be located within the facility, although the clock of course could be remote therefrom, for example, at a radio or television broadcasting source for transmission to the facility along with the radio or TV signals. The clock 10 in the embodiment shown should be integrated into the Formatter 12 which transforms the parallel digital form time signals received from the clock 10 to a serial digital form which is usable by downstream components of the system. By "parallel digital form" is meant a coded signal capable of containing multiple bits of information at a time and handled simultaneously; e.g. a coded signal in parallel digital form is used in the IBM 360 and thus is known to the art as is serial digital form which is processing information piece by piece, one bit at a time. The Formatter 12 suitable for use in the system is a data processor that digitizes information and assembles it in a serial digital code for the transmitter 14. In many installations an "off the shelf" digital clock 10 will be used to supply information to the formatter 12. They operate on a binary code that varies with manufacturers. Therefore, conversion of the code by the formatter 12 to the representation required by the end use of the system will vary as the binary code source varies. In a prototype a commercial digital clock 10 is used. It continuously exposes time in hours and minutes which is in its system coded in parallel digital form. That information is transferred to the formatter 12 which converts it to a serial digital form and transfers it to the transmitter 14. Commercial Tapes are available having time sources. They may be suitable but also require a custom Formatter 12 design to be used. Using the UTC signal as a source of time requires a totally different consideration because its time takes a full minute to receive. Therefore, The Formatter 12 must accumulate information for each minute. Seconds, miliseconds, and further breakdown of the minute if required must be supplied by the Formatter through alternative means keyed to the UTC signal for start of its counting. The coded time signal is transmitted by the transmitter 14 to time employing devices 16, 18, 20 by their direct coupling with electrical service 2 through receptacles 4 or through radio. The coupling to the electrical service 2 is in particular to the neutral or grounded leg. The transmission antenna is the feature used for coupling the device. It is directly connected to the grounded (wide) prong of a two prong male plug adapted for receipt in a conventional outlet receptacle in the facility. Only the grounded (wide) prong of plug requires insertion in receptacle for successful coupling of coded signal to electrical service 2. Insertion of both prongs is necessary to provide energy to transmitter 14. It should be noted that the coded time signal does not interfere with the A.C. power or with radio or television broadcasts being received by radios or televisions coupled to the electrical service 2. The coded time signal is a silent, non-visual program with respect to radios, televisions, or other equipment connected to and deriving power from the electrical service 2. Of course, once the coded time signal is transmitted to the electrical service 2 by the transmitter 14, the signal is available for pick-up at each electrical outlet receptacle 4, switch (not shown) or termination points within electrical service (now shown). The signal format received from the formatter 12 determines the design of the transmitter 14. Generally an off the shelf transmitter can be provided the additional features required for the transmitter 14 to serve the system. The transmitter's RF carrier is modulated by the serial data it receives. Thus the time employing devices 16, 18, 20 joined to either electrical service 2 or radio assume the information of the clock 10. Several time employing devices 16, 18, 20 are shown connected to the electrical service 2 at outlet receptacle 4. For example, a time display device 16 may be connected to one receptacle 4 and would include a display and a two prong male plug that provides energy to drive the time display 16 while also coupling the coded signal from the electrical service to the time display. The time display device 16 would include an electrical signal sensing means similar to that found in conventional clocks for transferring time information from the electrical service 2 to the time display 16 which could be a conventional light emitting diode, liquid crystal, electrochromic or other known displays. Thus, by simply plugging the time display device 16 into any receptacle 4 in the facility the time could be displayed and would correspond with that of clock 10. Likewise, a timer device 18 could be plugged into one of the outlet receptacles 4 for controlling lights, appliances, or other equipment within the facility. The timer device 18 would include an electrical signal sensing means for transferring time information from the electrical service 2 to the timing circuit of the device. And, one or more time employing devices 20 would be plugged into the outlet receptacles 4 and would include controlling devices such as manufacturing processes controllers, attendance clocks, security controllers, household devices, etc. that recognize and use the coded time signal directly in the facility. The time employing devices may range from simple to that of a microprocessor. Their functions vary greatly. In general, they serve to acquire data, analyze data or control systems. The system provides time which is the basis for measurement control and monitoring of the individual functions of the various devices. The information of interest the device serves may take the form of mechanical displacements, pneumatic pressures, fluid flow, radiations, temperatures, etc. Any physical phenomenon can be of interest and as such may be used to generate signals of interest to the monitor. All signals of interest must be converted to an electrical form such as voltage, current or impedance. Their value is the analog of the signal parameter being measured. The voltage signal changes in accordance with the variations of the signal it represents and is proportioned to the parameter. Similarly current or impedance variations can be used to represent the measurement parameter. Time employing devices 16, 18, 20 provide the change in energy from one form to electrical. They convert the signal of interest to an electrical form that is measureable. Their designs would be based on a very large number of different physical phenomena. The time employing devices may require the features of a Signal Conditioner integrated within them for converting the electric signal to a common form and range. The functions possibly required may be: voltage and current amplification, impedance transformation, calibration and referencing. The analog electronic equipment has reference powers sources that enable it to convert the electrical analog signals to a common scale and range. The time employing devices contain or are associated with features of an Analog to Digital Converter (ADC) which converts the signals from the devices to digital representation. Many types of time employing devices may be used with the system. These will produce many analog signals of interest. A single ADC can be shared among a number of the analog signal sources by using an analog multiplexer which is an electronic or electromechanical switch that by program control connects selected analog input channels to the ADC. The converter then produces as its output the digital representation of those channels. There are other time employing devices that are simple in design such as items that operate on or off by setting of time at the device much like a timer or items that record operating time such as meters. There are other simple devices that provided the benefit of a continuous time source are capable of acquiring data, analyzing data, or controling systems independently. FIG. 2 illustrates another embodiment of the system similar to that shown in FIG. 1 with the addition of program controller 22 and transmitter 24. The controller 22 would program various activities or sequences of events and that information would be transmitted to the electrical service 2 by the transmitter 24 at the time activity is to occur. The programmed controller 22 comprises a memory system that would maintain an address and time schedule for activities to occur. The transmitter 24 would be activated by coded instructions received from program controller 22. When alerted transmitter 24 would transmit directions. Connected to the outlet receptacles 4 of the electrical service 2 would be programmed devices 26 that recognize the coded programs and direct equipment accordingly for the purpose of control, monitoring, and/or accounting. The purpose of exemplary of such a programmed device would be a control for traffic signals, control for manufacturing processes, control for domestic services such as lights, thermostats, etc. Both FIGS. 1 and 2 also show that the transmitters 14 and 24, respectively, may be provided with antennae for air transmission of the coded signal to time employing devices 16, 18, 20 and 26 having antenna to pick-up the air transmission. FIG. 3 illustrates a system of the invention intended for facilities that require servicing of a number of consumers or equipment having a requirement for the ultimate accuracy of Coordinated Universal Time. For example, the master time signal would be transmitted by radio stations 30, or by cable or other means, scattered throughout the world. The system would include a UTC receiver 32 for receiving the master time signal and transferring it to the Formatter 34 which is similar to that described hereinabove with respect to FIG. 1 in that it converts the analog form to the aforementioned serial digital form representing time by hours and minutes which it then transfers to the transmitter 36 which is similar to that described hereinabove for FIG. 1 in that it transmits the time information to the electrical service 2 of the facility. Time employing devices 38, 40, 42 similar to those already described would receive the coded master time signal through outlet receptacles 4 in the electrical service 2. A highly accurate time signal is thus provided for use by the time employing devices. The time this system provides is guaranteed accurate because it is traceable to Greenwich Mean Time. Interruption in the transmission of the UTC eliminates production of time and loss of it in the system. If time is seen or available at any point in the system it is corrected time because only correct time is transmitted. Interruptions through loss of power would be overcome by having battery systems available to provide alternate power. FIG. 4 illustrates a system of the invention intended as a utility to some large areas such as a county, state, or nation. A small number of such utilities could serve the entire world. This system would also use the coordinated Universal Time source 50 which would transmit the master time signal to the UTC receiver 52 at the utility 54. The Receiver 42 receives and transfers the master analog time signal to the Formatter 56 which produces a serial digital signal as described hereinabove. The Utility Transmitter 58 produces an analog system that it transmits to widely dispersed facilities. At each facility, the analog signal is received by receiver 60 comprising a radio receiver and a feature that transfers the analog code it receives to the Formatter 62 which converts it to serial digital code described hereinabove. The transmitter 64 transmits the coded master time signal to electrical service 2 as described hereinabove for use by the time employing devices 66, 70, 72. As with system in FIG. 3 the FIG. 4 system also provides a guarantee that time it provides is accurate because it is traceable to Greenwich Mean Time. Interruption in the transmission of UTC eliminates production of time and loss of it in the system. If time is seen or available at any point in the system, it is correct time because only correct time is transmitted. Interruption through loss of power are overcome by having battery systems available to provide alternate power. Of course, the systems shown in FIGS. 3 and 4 can be provided with programmed controllers and programmed transmitters at the facility and/or at the utility to provide programmed activities to multiple users and/or facilities. As those skilled in the art the systems described hereinabove could have numerous advantages uses including, but not limited to, those listed here below: (a) as a standard time reporting system for use by regions, states, nations and the world. (b) as a means to provide time displays in lieu of conventional clocks or other timepieces. (c) as a means for reporting of frequencies of occurences or events, or cycles of operations in remote locations. (d) as a means for controlling devices and replacing conventional timers found on household equipment such as washers, dryers, stoves, etc. (e) as a means for controlling devices such as machine tools, processing equipment, inspection and monitoring equipment, and consumer products which now use timers or programmers attached or associated therewith. (f) as devices for use by surface, sea and air transportation vehicles (facilities) having an electrical gridwork for monitoring and controlling various systems and time displays thereon. (g) as a basis for computer and processor systems. (h) as a basis for navigation systems. The basis for all principle navigation systems is time. 1. Celestial navigation determines position of ships or aircraft by shooting the stars and/or moon with a SEXTANT. Exact Greenwich Mean Time at the very instant of shooting is required to complete computation of position. 2. "Great Circle Navigation" is the shortest distance between two points and is used in both sea and air travel. It is accomplished by making numerous course changes and maintaining each course for a closely controlled time. 3. Dead Reckoning navigation is the plotting of various courses on charts and maintaining them at a particular speed for a closely controlled time. 4. Depth of water below ship is found by measuring the length of time a signal travels from the hull of the ship to the bottom of the water and back. Commercial depth finders use this feature. Another aspect of the invention system is its adaptability for transmission of information from the location of the monitoring device 80, for example, a gas, water, or electric meter, fire detection device, security device, or process sensor device, to a third location to enable monitoring and for control thereof. In such an arrangement, see FIG. 5, the meter monitoring device 80 provides its information to Formatter 82 which appropriately codes the information similar to that described hereinabove for FIG. 1. Coded information is transferred to Transmitter 84 which delivers information similar to that described hereinabove via the electrical service or air. In addition, telephone and cable are alternate means of transmitting information. Information terminates at a remote monitor station 86 having memory (information & addresses) to compare coded signal with. Accounting or adoptive control functions are thus possible. Remote location for monitoring information would be main power generating station 88 or monitor station 86 having access to the main power distribution system that supplies power to the location containing the monitoring device 80. Of course, sensors of temperature, pressure, volume, velocity, density, flow, chemical composition, electrical parameters and the like can be used in lieu of the master clock discussed in the above embodiments to provide systems of the invention which distribute such information for use in the same manner that time information is distributed in the above embodiments. As used hereinabove and in the claims which follow, the term "electrical gridwork" should be understood to include not only the electrical service described in FIGS. 1-5 but also other grounded systems which may include, but are not limited to, the plumbing system, telephone system, cable system and the like within or operatively associated with a facility. Those skilled in the art will appreciate that certain preferred embodiments of the invention have been illustrated and that it is within the scope of the invention to make change, modifications and the like thereto within the scope of the apprended claims.

4y

BACKGROUND OF THE INVENTION This invention relates to a lever mechanism which may be affixed to a plurality of valve stems by appropriate cable and push rod assemblies for control thereof. In particular, it relates to a single-control lever mounted in a bracket assembly which has generally linear travel to control at least two valve stems in a construction machine. Control of hydraulic circuits in machinery, particularly construction machinery of the mobile type, for example, tracked vehicles, is generally accomplished through lever mechanisms. Operation of these various lever mechanisms is best accomplished with a minimum change of directions of the lever during positioning in the various operable positions. For example, in a tracked vehicle having a winch mechanism affixed to the rearward end of the vehicle it is appropriate to provide control of the winch by fore and aft movement of the winch control lever. Simple fore and aft control motion is more appropriate than combined lateral and fore and aft motion for winch control in that the operator may observe the particular load being winched into or away from the winching vehicle. To utilize the more conventional and somewhat complex winching patterns for control of a plurality of valve stems associated with such a winch mechanism tends to divert the operator's attention from the job at hand. A problem associated with a single-control lever in such a winching system is the necessity of controlling a plurality of valve stems. In any winching system, it is appropriate to select the direction the winch is to be rotated and secondly, to control the fluid rate delivered to the winch in order to control the speed of the winch and concurrently release any brake associated with the winch. Thus, a control lever must first select the direction of rotation of the winch, release the winch brake, and then finally, modulate fluid flow to the winch motor in accord with the desired rate of speed. To accomplish this in a two-directional (i.e., reel-in and reel-out) lever mechanism requires a particularly unique design since modulation control must be operable in both the reel-in and reel-out criteria. Although this problem has been described in relation to a winch operation, it should be apparent to those skilled in the art that a single-control lever to control a plurality of valve stems is not unique to the winch problem. Accordingly this invention is equally applicable to other hydraulic control systems. SUMMARY OF THE INVENTION This present invention is directed to overcome one or more of the problems as set forth above. Broadly stated, the invention is a lever mechanism comprising a bracket and a lever. The lever is pivotally mounted on the bracket for allowing limited rotational movement of the lever relative the bracket in first and second normally oriented planes. A first rod is also associated with the bracket and is movable longitudinally relative the bracket. Camming means are affixed to the pivot means and are responsive to rotational movement of the lever in the first plane for urging the first rod in first and second longitudinal directions. A second rod is associated with the pivot and is responsive to rotational movement of the lever in the second plane for longitudinal movement of the second rod relative the bracket. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an elevation view of a construction vehicle in which the present invention could be used. FIG. 2 is an elevation view partly in section and partly schematically of the lever mechanism that is the subject of this invention. FIG. 3 is the lever mechanism as shown in FIG. 2, also partly in section and taken at a side elevation. FIG. 4 is a plan view of the console plate utilized in this invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT This invention is described in relation to a winch control lever for operating a winch 6 mounted on a vehicle such as a tractor 7. It is to be understood that the lever mechanism described herein is equally applicable for use on other vehicles and for control of other hydraulic devices and the like. Referring to FIG. 2, lever mechanism 5 is shown in elevation and partly in section, with a schematic arrangement of valves which could be appropriate for control of winch 6. The various clutches and brakes necessary for operation of winch 6 beyond the valving structures are not herein shown as these clutches and brakes are well known in the art. A bracket assembly 10 forms the basis for mounting of the lever mechanism 5 to vehicle 7. Bracket assembly 10 may be tailored to the specific needs of the vehicle; however, it must be formed to receive a gimbel arrangement, such as pivot means 12, to allow arcuate movement of a lever 14 affixed thereto in at least two planes. These planes are coincident with the planes of the drawing in FIG. 2 and FIG. 3, and are substantially normal one to the other. Pivot means 12 is comprised of a first member 16 (see FIG. 3) which is journalled for rotation in bracket assembly 10 and has subtending therefrom at one end a cam plate 18. Affixed to first member 16 is a bifurcated element comprising two axially bored bearing members 20 and 22, each extending outwardly of first member 16 and each defining a bore 24 and 26, respectively, which form gudgeons or journals for the outwardly extending trunions 28 and 30 formed on a second member such as pivot block 32 to which lever 14 is affixed. It should be apparent to those in the art that lever 14 is effectively gimbaled relative bracket assembly 10 and may be rotated with rotational freedom. Also affixed to bracket assembly 10 by appropriate bearing means, such as a journalled shaft 33, is a cam lever 34. Cam lever 34 is affixed at one end as previously noted by journal shaft 33 to the bracket assembly 10, and carries proximate the midpoint thereof a cam roller 36, which is associated with cam lever 34 by means of a shaft 38. Shaft 38 may be affixed to cam lever 34 by appropriate fastening means, such as a nut 39 threadably engaged on shaft 34 and having disposed between nut 39 and cam lever 34 a locking member, such as lock washer 40. It is to be understood that cam roller 36 is free to rotate on shaft 38 to reduce frictional forces between cam roller 36 and cam surface 68 of cam plate 18. Cam roller 36 is for engagement with this lower surface cam surface 68 of cam plate 18 to act under the influence thereof. Such influence will cause an arcuate movement of cam lever 34 as a result of arcuate movement of lever 14 in the plane illustrated by rightward and leftward motion in FIG. 2. Affixed at the end of cam lever 34 may be a push rod 42. Push rod 42 reciprocates in a housing member 43 rigidly affixed to bracket assembly 10 by appropriate means well known in the art, such as subtending bracket 46 and locking member 48. Appropriate link means 50 may then interconnect push rod 42 with a modulating type valve 52 or the like wherein either system pressure or flow rate is to be controlled relative a second valve. Modulating valve 52 may also serve to bias cam lever 34 upwardly as shown in FIG. 2. Affixed to pivot block 32 is a second push rod 54 which is also fixedly associated with bracket 10 by means of a second bracket 56 rigidly affixed to bracket 10. A housing 58 is associated with bracket 56 by locking member 60. Push rod 54 is associated with housing 58 so that reciprocation may take place therethrough to operate a linkage means 64 and a 3-position valve such as valve means 62, which may control the rotational direction of a hydraulically operated winch motor (not shown). Affixed to bracket 10 is a console plate 66 which is slotted as shown in FIG. 4 to limit travel of lever 14 to a particular pattern for control of the aforedescribed winch. It is to be understood that the slotted pattern of console plate 66 may be modified for use in other installations. The pattern depicted here is particularly adaptable to the winch control of this invention. Operation of the lever mechanism described here should be apparent to those skilled in the art; however, in order to clarify the design and the operation, the following description is offered in elaboration. It is to be understood that the primary advantage of this particular camming arrangement is to insure that push rod 42 is moved downwardly as shown in FIG. 2 the same relative amount no matter in which direction in the plane of FIG. 2 that lever 14 is rotated in. In the environment herein described, rotation of lever 14 in the counter-clockwise direction as shown in FIG. 2 may accomplish a reel-out condition in the associated hydraulic winch motor, while rotation in the clockwise direction from the center position as shown in FIG. 2 will accomplish a reel-in capability. Specifically, the greater the movement from the center position wherein the lever rests in FIG. 2, the faster the hydraulic motor operating winch 6 will rotate. The position lever 14 has taken in FIG. 2 in the "brake-on" or stop position. Thus, motion of push rod 42 is accomplished through the cam plate 18 which defines the concave cam surface 68 so that movement of lever 14 urges cam roller 36 downwardly as illustrated in FIG. 2 along the cam surface 68 with the movement of cam roller 36 being proportional to the displacement of lever 14 in either direction from the neutral position as illustrated in FIG. 2. Concurrently, movement of lever 14 in the plane of FIG. 3 will reciprocate push rod 54 relative housing 58 and, thus, displace the valve stem of valve means 62 appropriately. In order to accomplish the necessary control of the hydraulic winch, the valve could have a minimum of three positions to obtain the steps of a "brake-on" position, a "reel-out" position, and, finally, a "reel-on" position. This should be apparent to those well versed in the art. However, it is necessary to control the movement of lever 14 so that displacement in the clockwise direction as indicated in FIG. 2 may first release the brake and then accomplish the reel-in capability of the associated winch. Such a valving structure is shown in more detail in U.S. Pat. No. 3,729,171, issued Apr. 24, 1973. Similarly, movement in the counter-clockwise direction shown in FIG. 2 must first release the brake and then accomplish the reel-out capability. Reference should be made to FIG. 4 wherein lever 14 would appear in the slot 70 and would thus follow the slot 70. It can be seen as lever 14 is moved downwardly to the position marked "reel-in" in FIG. 4, lever 14 will rotate in the plane of paper 3 and thus position the valve stem of valve 62 to the appropriate "reel-in" position with modulation occurring through the motion of cam roller 36 following cam surface 68. Similarly, motion in the upward direction from the position shown in FIG. 4 will first release the winch brake; that is, full modulation may occur in valve member 52 which could accomplish both the brake-off and the full speed operation of the hydraulic motor before shifting of the valve stem in valve means 62. Such motion could be used for a free-wheeling condition. It should be apparent to those in the art that a duplicate pattern could be repeated in the "brake-off," "reel-out" mode as indicated in the "reel-in" mode in FIG. 4. Although this invention has been described in reference to a particular embodiment for control of a winch in a construction vehicle, it is to be understood that other applications are equally appropriate. It is to be further understood that this invention is limited only by the appended claims.

4y

RELATED APPLICATIONS [0001] This application is a non-provisional application is a continuation-in-part of U.S. Non-Provisional application Ser. No. 15/223,545 filed Jul. 29, 2016 that in turn claims priority benefit of U.S. Provisional Application Ser. No. 62/198,136 filed Jul. 29, 2015; and U.S. Provisional Application Ser. No. 62/210,848 filed Aug. 25, 2015; the content of both of which are hereby incorporated by reference. FIELD OF THE INVENTION [0002] The present invention relates in general to photovoltaic (e.g., solar cell) or light detecting devices and in particular to a protrusion array—reflector/back electrode structure performing an optical refraction/reflection function thereby affording superior performance as measured by effectiveness, cost, or both. BACKGROUND OF THE INVENTION [0003] Solar cells traditionally have normally resorted to structures having textured (usually random) front surfaces and metal layer(s) back reflector/electrode structures to serve generally in both electrical conduction and optical roles (1). Metals have the advantage in the back of being able to serve as both reflector and conducting back electrode. Because of its excellent reflectivity, conductivity, and chemical properties, silver is usually the metal of choice for the reflector/electrode back contact (R/EBC) use. However, its cost can be a factor, especially in large device area applications such as solar cells. The processing step needed to apply a back reflector/electrode metal can also be time-consuming and costly, especially if it involves vacuum deposition. In these devices effectiveness as well as materials and manufacturing costs, or both are factors to be considered. The back reflector/electrode structure that would be very useful is one that would not degrade performance to any significant extent, if at all, when utilized and yet would avoid the use of an expensive metal thereby being beneficial by mitigating device cost considerations, removing metal chemical reactivity considerations, removing plasmonic loss possibilities (2-4), and simplifying processing. Such a back reflector/electrode structure employed as part of an architecture that also avoided the use of front texturing for light management would be excellent. Eliminating texturing, which often involves chemical etching or random surface growth, would improve processing. Thus, there exists a need for a solar cell architecture that is free of an expensive metal layer performing an optical reflector function and free of the use of texturing. [0004] In recent work, Kim et al. (4) used a 200 nm ZnO:Al back contact for a superstrate a Si:H thin film solar cell on glass microcone features on a glass substrate. Here the notation ZnO:Al represents Al doped ZnO (commonly denoted as AZO). The microcones with a base diameter D ˜1.5 μm were formed by employing a hard mask on, and then reactive ion etching (RIE), the glass substrate. These randomly positioned microcones were reported to have an aspect ratio A˜2 where this aspect ratio for microcones was defined as A=H/D, where H is the microcone height and D is its base dimension. Kim et al. termed A=H/D≧2 a high aspect ratio and their ˜2 microcones to be 3-D features (4). To explore increasing the performance of these superstrate cells, Kim et al added a back-reflector (BR) on the back of their solar cells. This BR was of the form of a ZnO:Al/Ag BR for some cells and of the form ZnO:Al/TiO BR for others. In this latter BR case, the TiO was in the form of nanoparticles. Performance of the ZnO:Al/Ag BR and ZnO:Al/(nanoparticle) TiO BR structures was compared to what they termed the “none BR ZnO:Al [AZO] back contact”. It was found that the ZnO:Al/(nanoparticle) TiO BR structure performed the best and the “none BR ZnO:Al [AZO] back contact” was the next best. Devices with the ZnO:Al/(nanoparticle) TiO BR were reported to give about 5% more short circuit current than the none BR ZnO:Al [AZO] back contact (4). SUMMARY OF THE INVENTION [0005] A photovoltaic or light detecting device is provided that includes a periodic array of dome or dome-like protrusions at the light impingement (front) surface and one of three reflector/back electrode designs at the device back (or rear). The beneficial interaction between an appropriately designed top protrusion array and these reflector/electrode back contacts (R/EBCs) serves (1) to refract the incoming light in a manner to thereby provide photons with an advantageous larger momentum component parallel to the plane of the back (R/EBC) contact and (2) to provide optical impedance matching for the short wavelength incoming light. Each reflector/back electrode form operates as a back light reflector and counter electrode to the periodic array of dome or dome-like structures. A substrate supports the reflector/back electrode. BRIEF DESCRIPTION OF THE DRAWINGS [0006] The present invention is further detailed with respect to the following drawings. These drawings are not intended to limit the scope of the appended claims, but rather to illustrate specific embodiments thereof. These drawings are not necessarily to scale. [0007] FIG. 1( a ) is a schematic cross-sectional view of an inventive embodiment in which nanoelements underlying each one of a periodic array of dome or dome-like protrusions are embedded within an active region; [0008] FIG. 1( b ) is a schematic cross-sectional view of an inventive embodiment in which nanoelements underlying each one of a periodic array of dome or dome-like protrusions are positioned on top of an active region [0009] FIG. 1( c ) is a planar view of the top electrode surface of the periodic array of dome or dome-like protrusions of either of the aforementioned drawings with no attempt made to depict an optimized flat area among domes; [0010] FIG. 1( d ) is a perspective view of the top electrode surface of the periodic array of dome or dome-like protrusions either FIG. 1( a ) or FIG. 1( b ) with no attempt made to depict an optimized flat area among domes; and [0011] FIG. 2 is a close up of a portion of two successive interfaces in a dome or dome-like protrusion as depicted in the aforementioned drawings; with refraction indices of materials selected to induce an incident photon redirection. [0012] FIG. 3 is a plot of an experimental EQE for two solar cell structures, where both have domes on the front surface with the arrangement seen in FIG. 1( a ) but sample A16 has a metal-less AZO reflector/back electrode contact whereas sample B16 has a metal Cr reflector/back electrode contact. The response of sample A16 is seen to be superior to B16, especially in the “red” wavelengths”. [0013] FIGS. 4( a )-( d ) Schematics showing various schemes(a)-(d) for positioning of dome or dome-like protrusion arrays between grids in front contact/back contact terminal configuration. [0014] FIG. 5 ( a ) State-of-the-art example of a back contact/back contact arrangement in which texturing (usually random) has been utilized at the front. (b) back contact/back contact arrangement in which the texturing has been replaced with a protrusion array. Any of the three forms of the R/EBCs listed in Table III may be employed with the protrusion array [0015] FIG. 6 ( a ) The computed A(λ) plot for a protrusion array—Form (2) R/EBC using AZO as the transparent conducting material (TCM). (b) The computed A(λ) plot for a protrusion array—Form (3) thick TCM/metal BR/E cell of the structure AZO/Al. In both (a) and (b), the resulting J SC values are given in the insets. Both (a) and (b) also have the computed A(λ) plot for a protrusion array—Form (1) Ag BR/E cell as well as the theoretical Yablonovich limit (YL). DESCRIPTION OF THE PREFERRED EMBODIMENTS [0016] The following detailed description is merely exemplary in nature and is in no way intended to limit the scope of the invention, its application, or uses, which may vary. The invention is described with relation to the non-limiting definitions and terminology included herein. These definitions and terminology are not designed to function as a limitation on the scope or practice of the invention, but are presented for illustrative and descriptive purposes only. [0017] Various terms used throughout the specification and claims are defined as set forth below as it may be helpful to an understanding of the invention. [0018] A metal-less back reflector/electrode for photovoltaic and light detection devices of the substrate configuration based on transparent conductive materials (TCMs) is one in which a metal plays no significant optical role. [0019] As used herein, “metal-less” back reflector-electrode or equivalently “metal-less” reflector-electrode back contact (R/EBC) denotes a structure (Forms (2) and (3)) wherein the one or more layers of this back reflector-electrode contact structure is devoid of any metal film having a significant optical function. The metal layer(s) normally used in back reflector/electrode structures for their optical role is (are) simply not present in Forms (2) and (3) of the invention. A metal may lie behind a metal-less R/EBC in various configurations of this invention but, if present, it has no required optical function and serves only as an electrical conduit (i.e., contact or interconnect, or both) and perhaps a structural support. Exemplary of reflector and electrode functioning metal films in Form (1) metal R/EBCs is an Ag layer which is often employed in such structures. [0020] The phrase “front surface of a photovoltaic or light detecting device” denotes the air/device region where incoming light first impinges. Correspondingly, the other side of the device is being denoted as the back (or rear) surface. These definitions apply to both superstrate and substrate device configurations. In conventional devices, the back surface region is often designed to reflect impinging light back through the device to enhance its utilization. Bragg reflectors with their layers of non-conducting dielectrics can be used for back reflectors (1). However, metals are most commonly utilized together with randomized front texturing. [0021] The phrase “dome-like” denotes an aspect protruding above a top planar surface, relative to the direction of normal light impingement. Each protrusion is imprinted, molded, deposited. or alternatively disposed over a nano-element “seed” having a conical, pyramidal, cylindrical, or other shaped aspect. In this latter case, the disposition technique employed (e.g., PECVD, printing, spraying, ablation) and the seed for producing the protrusion layers control the shape of the protrusion layers. [0022] In the invention disclosed herein, a back reflector/electrode for photovoltaic and detection devices of the substrate configuration is utilized for its optical coupling to the protrusion array eliminating or minimizing plasmonic losses in Forms (1)-(3) R/EBCs. The fabrication of this back reflector/electrode for a substrate device does not use the steps of hard mask deposition and etching of Kim et al. and it is not limited to the glass substrates of Kim et al. Uniquely, the invention reported here employs periodically arrayed dome or dome-like layered protrusions which are positioned at the front surface ( FIG. 1 ) and layered as schematically indicated in FIG. 2 in a cross-sectional view. The resulting refraction of impinging light redirects that light as seen in FIG. 2 . This redirection is due to the shape of the dome or dome-like protrusions as seen in FIG. 2 and the variation of the indices of refraction of its layers. [0023] The shape requirement for the layers of a protrusion for beneficial redirection properties may be quantified by employing the (normalized) surface normal vector {circumflex over (n)} at two successive surface points along a ray path; i.e., points 1 and 2 of FIG. 2 . The shape requirement for any two successive dome or dome-like layers in a protrusion can then be stated as: the horizontal component of the normalized surface normal vector at point 2 must be equal to or larger than the horizontal component of the normalized surface normal vector at point 1. The horizontal direction is defined by the “back plane” in FIGS. 1( a )-( d ) . Layer indices of refraction must increase or at least remain constant as the impinging light penetrates deeper into the photovoltaic or light detecting device. The objective of this protrusion orientation being away from the device ( FIG. 1 ), the protrusion topology, and the varying indices of refraction is to increase the component of the impinging photon momentum parallel to the planar region (defined by the back plane) of the back electrode depicted in FIGS. 1( a )-1( d ) . [0024] The fabrication of this protrusion array—back reflector/electrode architecture for a substrate device does not use steps such as hard mask deposition and etching and it is not limited to the use of glass substrates. As noted, the invention reported here employs “dome protrusions” or “dome-like protrusions” which are positioned at the front surface as schematically indicated in FIGS. 1( a ) and 1( b ) cross-sections, FIG. 1( c ) planar view, and in FIG. 1( d ) perspective view. [0025] These protrusions may include multiple layers, one or more of which may be the top electrode (a TCM). In particular, the protrusion may be covered by the top electrode as in FIGS. 1( a ) and 1( b ) . These protrusions may include multiple layers, one or more of which may be part of the active region, as seen in FIG. 1 ( a ) . The active region includes at least one of the absorber(s) and built-in electrostatic and/or effective field forming layers. Layer indices of refraction n must increase or at least remain constant as the impinging light penetrates deeper through protrusion layers. In the case where the active region has an active layer top surface that is at least partially in the protrusion, as seen in FIG. 1 ( a ) , the terminal protrusion layer before the active region has an n less than or essentially equal to that of the active region being encountered. In the case where the active layer top surface is not in the protrusion but is planar with the protrusions disposed thereon, as seen in FIG. 1( b ) , the terminal protrusion layer before the active region has an n larger or essentially equal to than that of the active region being encountered. [0026] The objective of having protrusion orientation pointing away from the device ( FIGS. 1( a ) and 1( b ) , the protrusion topology, and the varying indices of refraction is to increase or at least maintain the component of the impinging photon momentum parallel to the back plane depicted in FIG. 1( a ) and 1( b ) ; i.e., to increase the parallelity to the back contact of the impinging photon momenta. [0027] Broadly speaking choosing a dome or dome-like protrusion base dimension D, height H, and spacing L shown in FIGS. 1( a )-1( d ) , as well as the resulting aspect ratio A=H/D affects the efficacy of the momentum change function of these protrusions. Choosing these aspects of the topology as well as the layer by layer n variation and the amount of front surface covered by the protrusion base affects the impact of these characteristics on increasing the component of the impinging photon momentum parallel to the back plane (denoted in FIGS. 1( a )-1( d ) ). For a given D, the protrusion surface area should be made as large as possible and the amount of the front surface area not covered by protrusions (See FIGS. 1( c ) and 1( d ) should be made as small as possible subject to processing and economic constraints. For example, using uniform domes or dome-like protrusions of base dimension D which just touch in a hexagonal periodic pattern of spacing L will produce a protrusion covered front surface percentage of 90%. This is not achieved in FIGS. 1( c ) and 1( d ) , for drawing clarity. [0028] To function, the protrusion array—reflector/back electrode structure of the invention disclosed herein requires refracting dome or dome-like structures with the properties described and oriented to protrude away from the R/EBC as seen in FIGS. 1( a )-1( d ) . The inventive protrusion array—reflector/back electrode (Forms (1)-(3)) architecture of this invention does not necessitate an aspect ratio A such that A≧2 and therefore the architecture mitigates against the possibility of performance degradation due to sharp features. The important dimensions of the inventive protrusion array—reflector/electrode back contact architecture are the D, H, and L of the dome or dome-like protrusions; they define the topological features shown in FIGS. 1( a )-1( d ) including the size of the flat regions among the dome or dome-like structures. While not shown in FIGS. 1( a )-1( d ) , these flat regions may contain additional, smaller dome or dome-like features also which are positioned randomly or systematically among the protrusions of FIGS. 1( a )-1( d ) . Additionally, protrusion features and flat region features may (not shown) or may not be textured (random topology). [0029] The nano-elements of dimensions h, d, and L as seen in FIGS. 1( a )-1( d ) , if present, are seeds utilized mainly to guide protrusion formation during disposition of the dome or dome-like features or layers thereof and may be made using vacuum or non-vacuum deposition steps such as molding, printing, probe printing, etching, and imprinting processing. Their formation does not require glass hard-mask etching. The dome or dome-like protrusion array and the reflector/electrode back contacts function with, or without, the presence of the nano-element seeds of FIGS. 1( a ) and 1( b ) . As noted earlier, the key aspect of the reflector/back electrode invention disclosed herein is the refraction caused by the dome or dome-like features at the front surface. The back reflector/electrode part of this architecture may utilize substrates such as metal foils, glass foils, and organic materials illustratively including polyacetylene, polyphenylene vinylene, polypyrrole, polythiophene, polyaniline polyimide, or polyphenylene sulfide. The back reflector/electrode serves as the counter electrode to the front electrode which itself is the top layer of or is at least a part of the dome-like structures or of the active region. [0030] The metal-less reflector/back electrode structure, Form (2) of the three R/EBC forms of the invention disclosed herein, performs very well as seen from Tables I and II and FIG. 3 . Form (2) is seen from the description and FIGS. 1( a )-( d ) and 2 to differ from the back contacts of Kim et al. in a number of aspects including: (1) The back contacts of Kim et al. are for superstrate devices; (2) the “none BR ZnO:Al [AZO] back contact” of Kim et al. is labeled a non-back reflector structure whereas in the innovative Form (3) structure here a ZnO:Al [AZO] back contact would be specifically designed to function as a metal-less back reflector/electrode contact; (3) the refracting dome or dome-like structures of our invention are oriented to protrude away from the device absorber as seen in FIG. 1( a )-( d ) whereas the corresponding refracting structures of Kim et al are protruding into the device absorber; (4) our metal-less (Form (2)) reflector/back electrode back contacts do not necessitate A 2 and therefore mitigate against the possibility of performance degrading sharp features; (5) the important dimensions of our metal-less reflector/electrode back contacts are the D, H, and L of the periodic dome or dome-like features whereas they are the height and base of microcones for Kim et al.; (6) the boundaries of our structure defining the region to be filled with the active region are smooth thereby also helping to avoid the sharp boundary problematic features possible in the back contacts of Kim et al.; (7) the nano-elements seen in FIGS. 1( a ) and 1( b ) correspond to the microcones of Kim et al. but are made using techniques such as non-vacuum molding, probe printing, or imprinting processing and not glass hard-mask etching; (8) the metal-less reflector/electrode back contacts of this invention do not involve the use of nanoparticles in the R/EBC and therefore do not involve the use of the concomitant nanoparticle application step; and (10), as seen in Table II, the Form (2) metal-less reflector/back electrode contacts of this invention function essentially equally well with, or without, the presence of the nano-elements of FIGS. 1( a ) and 1( b ) . As noted earlier, the key aspect of the protrusion array—reflector/back electrode architecture disclosed here is the refraction caused by the protruding, periodic dome or dome-like features on the front surface and their optimal shape and index of refraction variations with successive layers. [0031] Modeling results used in the study of and design of the protrusion array—Form (2) metal-less reflector/back electrode architecture of this invention are summarized in Table I for the case of a metal-less AZO back reflector/(Form (2)) contact and, for comparison, for several metal back reflector/electrode (Form (1)) contacts using several types of metals. These comparisons are reported for front surface dome cells using solar cell short circuit current Jsc results for nc-Si absorbers of 400 nm thickness. The fact that a protrusion array—metal-less R/EBC (Form (2)) is seen to perform almost as well as a protrusion array—silver (Form (1)) contact is outstanding. [0032] Table II gives results for metal-less AZO back reflector/electrode contacts with nano-elements and without nano-elements. These results underscore the crucial role of the dome or dome-like structures of the front surface in reflector/electrode back contact devices. These results make it apparent that the nano-element principally plays a role in the fabrication process of shaping the dome or dome-like structures, if utilized. [0033] Table 1. Jsc values for various protrusion array—metal reflector/electrode back (Form (1)) contact cells and a protrusion array—metal-less R/EBC (Form (2)) cell. [0000] TABLE I Jsc for Various Metal Reflector/Electrode Back Contact Cells and a Metal-less Cell All with Domes (teff = 434 nm) Configuration Jsc (mA/cm{circumflex over ( )}2) Ag dome solar cell 30.64 Cr dome solar cell 22.6 Al dome solar cell 25.71 Au dome solar cell 28.54 Metal-less (AZO) dome 28.7 solar cell Table II Protrusion array—Form (2) metal-less AZO reflector/back electrode ncSi cells on polyimide. Cases with and without (w/o) nanoelements and with the absorber thickness adjusted (t eff ) for absence of the nanoelement are given. [0000] Metal-less AZO reflector/back electrode ncSi cells on polyimide (Absorber thickness t was 400 nm but this was reduced for the case when the nano-element was not present) configuration On PI AZO Metal-less 29.53 mA/cm{circumflex over ( )}2 AZO Metal-less w/o 29.14 mA/cm{circumflex over ( )}2 nanoelement AZO metal-less w/o 29.08 mA/cm{circumflex over ( )}2 nanoelement + teff adjusted [0034] An experimental comparison of the performance of two dome substrate solar cell devices with R/EBC Form (2) metal-less reflector/back electrode back contacts (ZnO:Al back contacts) and with R/EBC Form (1) metal reflector/back electrode back contacts (i.e., Cr back contacts) is presented in FIG. 3 . Both have domes on the front surface implemented using the nano-elements of FIG. 1( a ) but sample A16 has a metal-less AZO reflector/back electrode contact whereas sample B16 has a Cr reflector/back electrode contact. Chromium was employed here since it has high plasmonic losses in the wavelength region of interest. The red wavelength region response of sample A16 is seen to be superior due to the avoidance of plasmonic losses. These losses are present with the involvement of a metal (B16) as part of the back contact. [0035] As Table III makes clear, protrusion array—Ag R/EBC (Form (1)), protrusion array—metal-less R/EBC (Form(2)), and protrusion array—thick TCM/metal R/EBC (Form (3)) structures perform much better than the corresponding planar (no protrusion array) control cell. As may be further discerned, protrusion array—Ag R/EBC (Form (1)) structures perform only somewhat better than the corresponding protrusion array—metal-less R/EBCs (Form (2)). However, the latter has the distinct advantage of avoiding the use of an expensive metal. Table III makes the extremely interesting point that the protrusion array—thick TCM/Al R/EBC (Form (3)) architecture provides excellent performance. In fact, Table III shows that the short circuit current performance of the protrusion array—thick TCM/Al R/EBC can be better than that of the other two forms of R/EBCs. In other words, this protrusion array—thick TCM/Al R/EBC (Form (3)) architecture can avoid the use of Ag yet give performance equal to, or even somewhat better than, protrusion array—Ag R/EBC (Form (1)) architecture. [0036] All the forms of the protrusion array—R/EBC architecture disclosed herein may be utilized with thin or thick active regions composed of at least one barrier forming and at least one absorber material. Thick active regions may be, for example, what are termed wafers. All the forms of the protrusion array—R/EBCs architecture disclosed herein used one of the three R/EBCs forms listed in Table III. The disclosed architecture, in its various forms, may be employed in cells with a front contact/back contact arrangement; i.e., the +terminal is on one side of the cell and the −terminal is on the other side. The disclosed architecture, in its various forms, may also be employed in cells with a back contact/back contact arrangement; i.e., both the + and −cell terminals are on the back side of the cell. [0037] The front contact/back contact arrangement is characterized by a front collection grid (of TCM or metal materials). In this case, the architecture of this invention has protrusion positions located in between these current collecting grid lines, as shown in FIGS. 4( a )-( d ) . As seen in FIG. 4( a ) , the grid lines may be disposed, in the thin active region case, after all protrusion layers are present, if these layers are transparent conductive materials (TCMs). This insures front current collection. Alternatively, they may be positioned on any TCM layer of the protrusion which provides electrical continuity to the active region, as shown schematically in FIG. 4( b ) . In this scheme, the transparent layers in the protrusion above this contacted TCM layer (one is shown in the example of FIG. 4( b ) ) need not be conducting. One or more may be passivating, encapsulating, or protecting the cell structure. [0000] TABLE III Architecture comparison Cell architecture Features Best J SC for this architecture Planar top Conventional. No protrusion array 18.0 mA/cm 2 for Ag surface but same metal R/EBCs as is used R/EBC control- in Form (1) metal (Form (1)) R/EBCs (1) Protrusion Metal R/EBCs together with 30.7 mA/cm 2 for array- protrusion array. May have an protrusion array--Ag R/EBCs metal (Form ultra-thin (~0.5-10 nm) optical (1)) R/EBCs spacer, and/or contact or selective contact layer over the front of the metal. (2) Protrusion Nonmetal R/EBCs together with 29.5 mA/cm 2 for array- protrusion array, One or more protrusion array-- AZO metal-less all TCM layers involved in providing R/EBCs TCM (Form R/EBCs function which thereby (2)) R/EBCs determines TCM thickness. May have a metal at the backmost region with no significant optical function but serving as a contact and/or grid and/or mechanical support. May have an ultra-thin (~0.5-10 nm) optical spacer, and/or contact or selective contact layer over the front of the TCM region. (3) Protrusion Both TCM + Al (for cost saving) 30.8 mA/cm 2 for array--thick are involved in R/EBCs function protrusion array-- AZO/Al TCM/metal and has protrusion array. May have R/EBCs (Form (3)) an ultra-thin (~0.5-10 nm) optical R/EBCs spacer, and/or contact or selective contact layer over the front of TCM region. [0038] The nanoelements which may be used to control the protrusion locations in these schemes are positioned between the grid areas. This is done by approaches such as probe-type, molding, printing, or imprinting-type nanoelement positioning. [0039] As seen in FIG. 4( c ) , grid lines may be positioned in a planar surface active region case after all protrusion layers are present, if these layers are transparent conductive materials. They also may be positioned on any TCM protrusion layer which provides electrical continuity to the active region. This latter case corresponds to FIG. 4( b ) and its discussion. Another approach is to etch all the disposed protrusion films off thereby defining grid areas and subsequently forming the grids through steps involving standard lithography/deposition/etching processing. The etching would be done down to a doping layer as seen in FIG. 4( d ) . The analogous processing can be done for the case in which the absorber region is in the protrusion with the corresponding doping layer incorporated into the active region. [0040] In the case of a back contact/back contact arrangement, both the + and −cell contacts are on the back side of the cell. This results in two sets of contacts at the back. FIG. 5( a ) gives a state-of-the-art example, for comparison, of a back contact/back contact arrangement in which texturing has been utilized at the front. As seen from FIG. 5( a ) , some method must be used to bring the front electrode current and voltage to the cell back. In the examples of FIG. 5 , this is accomplished by a so-called “wrap-around” approach using trenching with the trench containing the required current carrier material. FIG. 5( b ) shows the type of back contact/back contact arrangement in which the texturing of FIG. 5( a ) is replaced with the protrusion array disclosed herein. Any of the three forms of the R/EBCs listed in Table III may be employed with the protrusion array in back contact/back contact arrangements. Whichever R/EBC is utilized, it obviously must be located at the back in FIG. 5( b ) to not short circuit to the contact coming from the cell front. [0041] Since L is the spacing between the protrusions (and essentially the same as D), as well as being the spacing between, if used, the nanoelements seeding the protrusions in their hexagonal lattice, the spacing in between trench edges in FIG. 5( b ) should be roughly equal to or somewhat larger than mL where m is an integer number. However, this protrusion array spacing constraint may not be strictly followed if not doing so advantageously reduces cost and increases simplicity. [0042] Returning to the structure of the back reflector/electrodes, it is noted that the periodic protrusion array—R/EBC architecture of this invention in its Form (2) and Form (3) versions of Table III can require optimization of the TCM series resistance versus the optical effectiveness for these types of architecture. This can be done using a variety of thicknesses and of TCMs including topological 2-D materials such as graphene. The TCM layer thickness in the R/EBC of a Form (2) R/EBC cell may lie in the range of about 0.2 to 400 nm or thicker depending on the resistivity and transmissivity of the TCM used. The TCM layer thickness in the R/EBC of a Form (3) R/EBC cell may lie in the range of about 0.2 to 400 nm or thicker as dictated by the resistivity and transmissivity of the TCM. [0043] The experimental ( FIG. 3 ) and modeling ( FIG. 6 a ) results for protrusion array cells with Form (2) R/EBCs demonstrate that excellent performance can be obtained from the protrusion array-metal-less all TCM R/EBC (Form (2)) cell architecture. In the experimental and modelling results presented, AZO is the TCM employed in a metal-less R/EBC device. Other TCMs including 2-D materials such as graphene may be utilized. The results given in FIG. 6( a ) and listed in Table III show specifically that protrusion array metal-less AZO R/EBCs can achieve, counterintuitively, J SC performances which are almost as good as protrusion array-Ag R/EBC Form (1) cells. As noted earlier, this obviously offers the avoidance of the use of Ag or any other metal film with an optical function within the R/EBC of cells, when advantageous. [0044] The performance of protrusion array—Form (1) R/EBC cells is superior to that of their corresponding planar (no protrusion array) cells. For the situation when the metal is Ag in the Form (1) cell, the J SC is increased by 70% over the J SC of the corresponding planar cell. However, it is very important to stress that the Form (3) periodic protrusion array—thick TCM/metal BR/E cells can give behavior (See FIG. 6( b ) ) that is superior to that of protrusion array—Ag Form (1) R/EBC cells. Surprisingly, this can occur even when using Al, with its inherently larger plasmonic losses compared to Ag, as the metal in the thick TCM/metal Form (3) R/EBC cell of FIG. 6( b ) . This outstanding performance may be seen in the plots and J SC tabulations in FIG. 6( b ) . CITED REFERENCES [0000] (1) S. Fonash, Solar Cell Device Physics, Elsevier (2010) (2) C. Ballif, J. Appl. Phys. 2009, 106, 044502. (3) V. E. Ferry, A. Polman, H. A. Atwater, ACS Nano. 2010, 5, 10055. (4) Jeehwan Kim, Corsin Battaglia, Mathieu Charrière, Augustin Hong, Wooshik Jung, Hongsik Park, Christophe Ballif, and Devendra Sadana, Adv. Mater. 2014, 26, 4082. [0049] While three exemplary embodiments have been presented in the foregoing detailed description, it should be appreciated that a vast number of variations exist. It should also be appreciated that the exemplary embodiments are only examples, and are not intended to limit the scope, applicability, or configuration of the described embodiments in any way. Rather, the foregoing detailed description will provide those skilled in the art with a convenient road map for implementing the exemplary embodiments. It should be understood that various changes can be made in the function and arrangement of elements without departing from the scope as set forth in the appended claims and the legal equivalents thereof.

4y

BACKGROUND OF THE INVENTION This invention concerns an apparatus for selectively connecting any one of a plurality of inlet pipes to any one of a plurality of outlet pipes. It is directed in particular, but not exclusively, to the circulation of petroleum products. In multiline fluid distribution installations the requirement routinely arises of being able to connect any one of several inlet lines to any one of several outlet lines with the number of inlet and outlet lines possibly being large, for example in the order of 15 or even more. It has already been envisaged to dispose the inlet lines and the outlet lines in parallel planes and in two directions perpendicular to these planes and to provide the end of each line with a telescopic ferrule adapted to be extended parallel to these planes into contact with the telescopic ferrule of any one of the lines of the other kind. This has various disadvantages, however. The use of telescopic ferrules leads to problems with sealing, guiding and mechanical stresses which in practice limit the application of this solution to small numbers of inlet and outlet lines. Furthermore, the telescopic ferrule solution is ill suited to automation. Also, and more importantly, the use of telescopic sections necessarily implies a variation in inside diameter which results in significant local deterioration of the effectiveness of scraping clean the walls of an inlet and an outlet line temporarily connected to distribute a liquid, and to remove any traces of this liquid likely to contaminate another liquid that might then flow in one or other of these lines. SUMMARY OF THE INVENTION The invention is directed to alleviating the aforementioned disadvantages by providing a "liquid switching station" formed of pipes which can all be scraped clean, and which lends itself to the (optionally simultaneous) connection of a large number of inlet lines to a large number of outlet lines in all possible combinations and in a way lending itself to automation. To this end the invention comprises an apparatus for selectively and temporarily connecting any one of a plurality of first fixed pipe sections to any one of a plurality of second fixed pipe sections. The apparatus includes an ordered first plurality of first pipe coupling sections having coupling flanges along an imaginary coupling plane and movable by a specific amount along a plurality of adjacent first guides parallel to a first direction in said imaginary coupling plane and offset parallel to a second direction in said imaginary coupling plane. Each first pipe coupling section is connected by one of a plurality of first deformable pipes to one of the plurality of first fixed pipe sections, which first fixed sections are at least approximately perpendicular to said imaginary coupling plane and offset parallel to said second direction, said first deformable pipes being deformable in planes of deformation parallel to said first direction. The apparatus further includes an ordered second plurality of second pipe coupling sections having coupling flanges along said imaginary coupling plane and movable by a specified amount along a plurality of adjacent second guides at least approximately parallel to said second direction and offset parallel to said first direction. Each of the second pipe coupling sections is connected by one of a plurality of second deformable pipes to one of the plurality of second fixed pipe sections, which second fixed sections are at least approximately perpendicular to the imaginary coupling plane and offset parallel to said first direction, said second deformable pipes being deformable in planes of deformation parallel to said second direction. The plurality of first pipes as a unit face the plurality of second guides as a unit so that each first coupling section can be aligned with any of the second sections and vice versa. Each of the first coupling sections comprises a pipe coupler adapted to couple the flange thereof to that of any of the second coupling sections, and the first and second fixed sections, the first and second deformable pipes and the first and second movable coupling sections have the same constant inside diameter. The preferred aspects of the invention, some of which may be combined with each other, comprise: each first deformable pipe is formed by at least two intermediate sections parallel to the associated plane of deformation parallel to said first direction and articulated to each other and to one of the first fixed sections and to one of the movable coupling sections by pipe swivel joints with axes perpendicular to said plane associated with said first deformable pipe, and each second deformable articulation is formed by at least two intermediate sections parallel to the associated plane of deformation parallel to said second direction and articulated to each other and to one of the second fixed sections and one of the second movable coupling sections by pipe swivel joints with axes perpendicular to said plane associated with said second deformable pipe; the first deformable pipes have parallel planes of deformation perpendicular to the imaginary coupling plane, and the second deformable pipes have parallel planes of deformation also perpendicular to the imaginary coupling plane; each deformable pipe is made up of two sections; the first direction is perpendicular to the second direction; the first direction is horizontal and the second direction is vertical; each first or second coupling section is mounted on a carriage movable between two of the first or second guides and displaced by a motor associated with said carriage and controlled by a centralized automatic control system; said motor is hydraulically operated and is on the carriage; each carriage is provided with a position sensor adapted to sense markers characteristic of possible coupling positions of said carriage on a guide associated with said carriage; and the first fixed sections and the second fixed sections are each more than five in number, between five and 20, for example, and preferably between eight and 20. Additional objects, characteristics and advantages of the invention will emerge from the following description given by way of non-limiting example with reference to the appended drawings. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a diagrammatic view in elevation of a pipe connection apparatus in accordance with the invention, for selectively connecting a plurality of inlet pipe lines, as viewed in the direction of the arrow D1 in FIG. 2, to a single outlet pipe. FIG. 2 is a plan view of the FIG. 1 installation showing a single inlet pipe. FIGS. 3A and 3B are views, on an enlarged scale, showing two successive steps of coupling an inlet pipe and an outlet pipe. FIG. 4 is a view in side elevation, and on a yet larger scale, of a pipe coupler of FIGS. 3A and 3B. FIGS. 5A and 5B are views in vertical central section of the coupler of FIG. 4, showing it in, respectively, open and closed configuration. FIG. 6 is an end elevation of the coupler of FIG. 4. FIG. 7 is a partial schematic view of the installation of FIGS. 1 and 2 with its hydraulic, electronic and data processing equipment. FIG. 8 is a view in elevation similar to FIG. 1, showing another selective connection apparatus incorporating an alternative embodiment of the means for maneuvering the pipe coupling sections. DESCRIPTION OF THE PREFERRED EMBODIMENT FIGS. 1, 2 and 7 show a selective connection apparatus 1 adapted to connect any one of multiple inlet pipe lines denoted A through P, to any one of multiple outlet pipe lines denoted 1 through 17. The installation 1 comprises a plurality of first fixed pipe sections 2A through 2P with horizontal parallel axes spaced and residing in a vertical plane, that is aligned parallel in a vertical plane, and adapted to be connected to the inlet lines A-P. The pipe sections 2A-2P end on the righthand side in downwardly directed pipe elbows. The first fixed pipe sections are connected to respective first deformable and identical pipes 3A through 3P, each pipe formed by two horizontal intermediate pipe sections 3'A through 3'P and 3"A through 3"P terminating at upwardly or downwardly directed pipe elbows. The elbow at the end of each of the first fixed sections 2A-2P is pivotably connected in a sealed manner by a pipe swivel joint to an elbow at the end of a corresponding first intermediate section 3'A-3'P to form a first vertical axis elbow articulation 4A-4P. Similarly, each horizontal intermediate pipe section 3'A-3'P is connected to one of the horizontal second intermediate pipe sections 3"A-3"P by a vertical axis second pipe swivel joint 5A-5P, and these horizontal intermediate pipe sections are connected by third vertical axis pipe swivel joints 6A-6P to a plurality of first pipe coupling sections 7A-7P. The various elbow end parts in these swivel joints come face to face in coincident horizontal planes. The first pipe coupling sections 7A-7P have parallel horizontal axes, and coplanar coupling flanges 8A through 8P along a common imaginary vertical coupling plane denoted P in FIGS. 3A and 3B. These first pipe coupling sections are movable along adjacent and horizontal guides 9A-9Q. The number of guides is one more than the number of pipe inlet sections, each first pipe coupling section passing between two guides. The guides are coplanar in a vertical plane, their ends being attached to a rectangular frame 10. Facing the equidistant and horizontal first guides 9A-9Q, and parallel to them, is a plurality of equidistant and vertical guides 11-1 through 11-18 attached to a second vertical rectangular frame 12 fastened to the first frame 10 by crossmembers 13. Along these vertical guides are slidably mounted second pipe coupling sections 14-1 through 14-17 with parallel horizontal axes, the number of which is one less than the number of vertical guides, each second pipe coupling section passing through between two such guides. The second pipe coupling sections include coplanar coupling flanges 15-1 through 15-17 along the imaginary coupling plane P (FIGS. 3A and 3B). Because the first and second frames 10 and 12 face each other, and because the first and second pipe coupling sections extend along the plane P but on respective sides thereof, any one of the first pipe coupling sections 7A-7P can be brought into alignment with any one of the second pipe coupling sections, and vice versa. The second pipe coupling sections 14-1 through 14-17 are respectively connected to second deformable pipes 16-1 through 16-17 that are identical to each other and are formed by two intermediate pipe sections 16'-1 through 16'-17 and 16"-1 through 16"-17 disposed in respective parallel vertical planes. The second deformable pipes are connected to a horizontal series of second fixed sections 17-1 through 17-17 with coplanar parallel axes in a horizontal plane and adapted to be connected to the outlet lines. The second pipe coupling sections, the intermediate sections and the second fixed sections have right angle elbow at their ends, directed towards the left or towards the right, conjointly forming first, second and third horizontal axis pipe swivel joints respectively denoted 18-1 through 18-17, 19-1 through 19-17, and 20-1 to 20-17. For the same deformable pipe these various elbows come face to face in swivel joints in coincident vertical planes. It will be understood that the first deformable pipes 3A-3P are offset vertically and deform in planes parallel to the first horizontal guides 9A-9Q, and that the second deformable pipes 16-1 through 16-17 are offset horizontally and deform in vertical planes parallel to the vertical second guides 11-1 through 11-18. Also, the first and second fixed pipe sections, offset either vertically or horizontally, are disposed opposite each other and have parallel axes perpendicular to the imaginary coupling plane. In this way the set of first and second guides enables (optionally simultaneously) establishing communication between any of the first fixed pipe sections 2A-2P and any of the second fixed pipe sections 17-1 through 17-17. The details of the guidance and coupling of the first and second pipe coupling sections is shown in FIGS. 3 through 6 with regard to a first coupling section 7A and a second coupling section 14-1. The various guides 9A-9Q and 11-1 through 11-18 may have a cross-section in the shape of a prism, lozenge or square (in the illustrated embodiment). Along each guide but one (there is one more guide than there are pipe coupling sections) extends a rack 21A, etc., or 22-1, etc., with which meshes a pinion 23A, etc., or 24-1, etc., carried by the shaft of a motor 25A, etc., or 26-1, etc. (such as a slowly rotating hydraulic motor) on a carriage 27, etc., or 28-1, etc. Each pipe coupling section is provided with two grooved rollers 30 (FIGS. 3A and 3B), made from polyurethane for example, adapted to roll on the facing edge of the guide for the carriage in question. Each first carriage 27A, etc. incorporates a position sensor 31A, etc. (in practice a proximity sensor), while on an associated horizontal guide 9A, etc., are bosses 32-1, etc., respectively associated with the second pipe coupling sections 14-1, etc., and adapted to be sensed by the position sensor 31A when the first coupling section 7A is aligned with the location into which the second pipe coupling section 14-1 associated with this boss must be brought in order to be coupled to that first pipe coupling section. Similarly, each second carriage 28-1, etc. incorporates a position sensor (not shown) analogous to the sensor 31A, etc. and adapted to sense any one of a series of bosses (not shown) provided on the vertical guide associated with the second carriage and respectively associated with the possible positions along this vertical guide of the various first pipe coupling sections. This enables accurate automatic positioning of the carriages by the motors. Although not shown, sensors indicating the end of, and thus limit travel on, the guides also are included in a preferred installation. Mounted on each of the first pipe coupling sections is a coupler 40 of any appropriate known type, in this instance hydraulically operated, as shown best and by way of example in FIGS. 4 through 6. The coupler 40 comprises a sleeve 41 forming a cam sliding axially on the coupling section in question (7A is shown) to define a variable volume chamber 42 communicating with a hydraulic control circuit, such as 50 in FIG. 7, and cooperating with a plurality of levers 43 substantially axially oriented with respect to transverse axes. Each lever 43 comprises a cam follower finger 43A at one end and, at the other end, a jaw 43B adapted to fit on and press together in a fluid-tight manner the flange 8A of the section 7A and the flange 15-1, etc. of the second pipe section to be coupled to that section 7A, and spring member 44 urges the jaws 43B apart. Sensor 45 (FIGS. 3A and 3B) are provided on each of the second pipe coupling sections to sense abutment members 46 of the first pipe coupling sections, thereby monitoring the presence of one of the first pipe coupling sections and the open or closed condition of the coupler 40. Additionally, sensors 47 are provided to monitor the open/closed state of the coupler. To provide some play, such as a few millimeters, between the flanges of the first and second pipe coupling sections during their relative movement, and to avoid any damage to their contacting surfaces and the gaskets provided on them a resilient system comprising springs 48 (FIGS. 3A and 3B) is preferably provided between the flanges 15-1, etc. and the associated carriages so as to force these flanges apart when the jaws of the associated coupler are moved apart. FIG. 7 shows the main component parts of an automatic control system for an installation of this kind, the system comprising a hydraulic circuit 50 associated with a programmable automatic controller 51, a display screen 52, and an optional manual control station 53. The circuit 50 includes a power source 54 of any appropriate known kind (for example a pump rated at 12 liters/minute at a pressure of 140 bars) and, associated with each first or second fixed pipe section, a distribution unit 55A, etc., 56-1, etc. and hoses (not shown) connected to the motors 25A, etc., 26-1, etc. and to the couplers 40. During translation movement of each coupling section the associated position sensor (31A, for example, as seen in FIG. 3A) sends a pulse to the automatic controller each time that it senses a boss (32-1, for example). These pulses are counted and memorized by the automatic controller which therefore knows the position of each coupling section. One such automatic controller suitable for this purpose is a TELEMECANIQUE TSX47/30 that receives the signals from the various sensors and operates appropriately on the electrohydraulic components of the hydraulic circuit 50. The screen 52 and an associated keyboard are used to input data and to display the status of the installation in real time, for example showing the respective displacements of the two pipe sections along a line and a column up to and including their coupling together. The operator selects the numbers/letters of the sections to be connected on the keyboard, and the screen shows the instantaneous positions of these two sections, whether available or not (i.e. uncoupled or still coupled to another section). The connection operations are carried through in the following order (after any necessary decoupling has been carried out): the horizontally movable section is moved to the selected point of connection, the screen showing the position in real time; the vertically movable section is moved until the connection position is sensed; the drive system is stopped and immobilized; the hydraulic coupler is closed, this being verified by the monitor screen which shows that the connection has been made. Transfer of fluid product through the connected pipes is then authorized, such as by appropriate signals produced in the automatic controller for use in the overall process. FIG. 8 shows an alternative embodiment of pipe connection apparatus in which the carriages are moved by nuts 60 fastened to the carriages and cooperating with screws 61 driven by fixed motors 62. As an example of the size of a real-life apparatus according to the present invention, the frames 10 and 12 are about 10 meters high and 11 meters wide, the planes containing the axes of the first and second fixed pipe sections intersect these frames respectively along their vertical and horizontal median lines, the distance between adjacent pipe sections is 0.6 meter for outside diameters of 9.1 meter, and the first and second fixed pipe sections are separated by a distance of approximately 10 meters. The foregoing description has been given by way of non-limiting example only, and numerous variations may occur to those skilled in the art without departing from the spirit and scope of the invention.

4y

CROSS REFERENCE TO RELATED APPLICATIONS [0001] The present application claims priority under 35 U.S.C. §119(e) of U.S. Patent Provisional Application Ser. No. 61/970,031, filed Mar. 25, 2014, the disclosure of which are incorporated by reference herein. GOVERNMENT RIGHTS [0002] This invention was made with government support under NIH Grant Number 4R33AI100164-04, titled “Bioluminescent Reporter Phage for the Diagnostic Detection of Shigellosis”. The U.S. Government has certain rights in the invention. BACKGROUND [0003] Acute diarrheal diseases are the second leading cause of death among infectious diseases. Of these, shigellosis, also known as bacterial dysentery, is a global human health problem. Shigellosis, caused by the genus Shigella , is a significant cause of morbidity and mortality, accounting for 164 million cases worldwide and 1.1 million deaths annually, most notably among children under 5 years old. The vast majority of infections occur in developing countries where poor sanitary conditions, contaminated food and water supplies, malnourishment, and overcrowded conditions are prevalent. However, shigellosis is also common in the U.S., accounting for approximately 450,000 cases per year. Shigellosis is highly contagious; the infectious dose has been estimated at 10-100 cells, and is usually transmitted by the fecal-oral route. Symptoms include loose stools mixed with blood and mucus, which are usually accompanied by abdominal cramps and fever. In the majority of cases, the disease is self-limiting. However, in severe cases, shigellosis is life-threatening and requires appropriate medication. [0004] Shigella is a member of the Enterobacteriaceae. Organisms are small, non-motile, fastidious Gram-negative facultative anaerobic bacilli. The four species of Shigella are divided into a number of different serotypes: S. dysenteriae types 1-13; S. flexneri types 1-15; S. sonnei type 1, and S. boydii types 1-18. Of these, S. flexneri type 2a, and S. dysenteriae type 1 are responsible for the majority and the most severe infections, respectively. [0005] Mucus and blood in stool samples are typical features of bacterial dysentery; however, the diarrheal stage of infection cannot be distinguished clinically from other bacterial, viral, and protozoan infections. Presumptive identification of Shigella infection can be made by culturing bacterial samples onto semi-selective medium, e.g., MacConkey or deoxycholate citrate agar, or highly selective media such as xylose-lysin deoxycholate, hektoen enteric, or Salmonella - Shigella agar. Confirmatory identification using real-time PCR analysis can expedite detection with sensitivity limits of detection as low as 10 3 CFU/g of stool. However, the cost of molecular assays can be prohibitive to their adoption, especially to developing countries where bacterial dysentery is endemic. [0006] Due to their inherent bacterial specificity, bacteriophages (phages) have been developed as diagnostic devices, in particular as reporters, for bacterial pathogens including Mycobacterium tuberculosis, Yersinia pestis, Bacillus anthracis, Salmonella enterica , and Listeria monocytogenes . There is a need for a reporter phage assay as a diagnostic tool for detection of the leading causes of bacterial dysentery. BRIEF DESCRIPTION OF DRAWINGS [0007] FIG. 1 is a schematic illustration of LuxAB genomic location according to one example of the claimed technology. [0008] FIG. 2 shows the PCR identification of Shfl25875::luxAB according to one example of the claimed technology. [0009] FIG. 3 shows a growth curve of S. flexneri culture infected with Shfl25875 according to one example of the claimed technology. [0010] FIG. 4 is a chart showing the signal response time of S. flexneri culture mixed with Shfl25875::luxAB according to one example of the claimed technology. [0011] FIG. 5 is a chart showing the sensitivity limit detection of one example of the claimed technology. [0012] FIG. 6 is a chart showing antibiotic susceptibility profiles of S. flexneri ATCC 25875 generated with ampicillin. [0013] FIG. 7 is a chart showing antibiotic susceptibility profiles of S. flexneri ATCC 25875 were generated with ciprofloxacin. [0014] FIG. 8 is a chart showing reporter phage detection of S. flexneri from spiked human stool. [0015] FIG. 9 is a chart showing detection of S. sonnei 9290 and S. flexneri 7-3510 with Sdys9750::luxAB according to another example of the claimed technology. [0016] FIG. 10 is a chart showing detection of S. sonnei 9290 and S. flexneri 7-3510 with Sdys12039::luxAB according to still another example of the claimed technology. DESCRIPTION [0017] For the purposes of promoting an understanding of the principles of the claimed technology and presenting its currently understood best mode of operation, reference will now be made to the embodiments illustrated in the drawings and specific language will be used to describe the same. It will nevertheless be understood that no limitation of the scope of the claimed technology is thereby intended, with such alterations and further modifications in the illustrated device and such further applications of the principles of the claimed technology as illustrated therein being contemplated as would normally occur to one skilled in the art to which the claimed technology relates. [0018] The disclosed technology describes the development of a reporter phage assay as a diagnostic tool for detection of the leading cause of bacterial dysentery, S. flexneri . In one example, wastewater samples were screened for the presence of phages displaying broad host range. One phage, Shfl25875, which displayed the broadest S. flexneri tropism, was characterized by genome sequencing, and was then engineered with the genes encoding bacterial luciferase to generate a ‘light-tagged’ reporter phage. Shfl25875::luxAB rapidly transduces bioluminescence to S. flexneri with high sensitivity, thereby providing a useful diagnostic reagent. Furthermore, as shigellosis is most problematic in developing countries where health-care expenditures are extremely limited, the low cost of phage-based assays are particularly attractive. Bacterial Strains and Culture Conditions. [0019] Bacterial strains were purchased from the NIH Biodefense and Emerging Infections Research Resources Repository ( Shigella spp., S. enterica, L. monocytogenes, Yersinia enterocolitica, Klebsiella pneumoniae, Escherichia coli ), the American Type Culture Collection ( Shigella spp. and K. pneumoniae ), and the Bacillus Group Stock Center ( Bacillus cereus ). Some Shigella isolates were from outbreaks in South America (Guatemala and Chile). Bacteria were grown in Luria-Bertani (Enterobacteriaceae) or Brain Heart Infusion ( B. cereus and L. monocytogenes ) media at 37° C. with aeration. Unless otherwise stated, isolated colonies were incubated in 2 mL of media for 18-24 h to generate saturated cultures. Cultures were then diluted 1:50 to 1:200 in fresh media and incubated until A600 of 0.2 (for bioluminescent assays) or 0.4 (for phage titering and host range studies). Where indicated, bacteria were enumerated by determining colony-forming units (CFU) after 18-24 h growth at 37° C. [0000] Isolation of Shigella Phages from Environmental Sources and Phage Propagation. [0020] Raw wastewater samples (40 mL aliquots) were processed immediately by the addition of NaCl (final 0.7 M) and CaCl 2 (final 5 mM) with mixing for 30 min at 30° C. Particulate matter and bacteria were removed by centrifugation (4,000×g, 10 min, 4° C.), and the supernatant was made 9% (w/v) polyethylene glycol 8,000 to precipitate phages. After 3 h at 4° C. with gentle mixing, the precipitate was collected by centrifugation (11,000×g, 30 min, 4° C.) and was then gently resuspended in SM buffer supplemented with 5 mM CaCl 2 before storing at 4° C. [0021] Shigella phages were isolated using S. flexneri serotype 2a and S. dysenteriae serotype 1 as hosts using soft agar overlays. Individual plaques were picked, serially diluted in SMC buffer and thrice plaque purified to ensure clonality of the isolated phage. Phages were then amplified in liquid culture using growing cultures until lysis, and phage lysates were clarified by centrifugation and filtration. [0022] Host range determination of phages was performed by spotting phage dilutions using Shigella spp. (73 strains), closely related Enterobacteriaceae species (39 strains), and clinically relevant non-Enterobacteriaceae (10 strains). Phage DNA Sequencing. [0023] Phage DNA was prepared and sequencing was performed by the Medical University of South Carolina Proteogenomics Facility using Ion Torrent Sequencing. The genome sequence of Shfl25875 is found at GenBank KM407600. [0000] Construction and Generation of Recombinant Shfl::luxAB Reporter Phage. [0024] Vibrio harveyi luxA and luxB genes were used as the reporter and were targeted for integration downstream of, and in the same orientation as gene 32 at position 146,610 by within the phage genome ( FIG. 1 ). LuxAB was targeted for integration into the phage genome using homologous recombination. Recombinant luxAB-phage were screened and selected for based on the ability of infected cultures to acquire a bioluminescent phenotype. Recombinant Phage Verification. [0025] To identify the presence of luxAB, and to confirm that integration had occurred at the correct site, cell-free phage supernatants were analyzed by PCR. Internal primers were designed to detect luxB (5′ primer ATCGACCAACGGATTCTCAG; 3′ primer ACTTCTTTGCTCGTCGCATT, product size of 184 bp). Primers were also designed to span the 5′ and 3′ integration junction sites (5′: 5′ primer CTTGTCCGTTTGAAGGTGCT; 3′ primer GCTTTGCCCAGATTAACCAA, 511 bp product: 3′: 5′ primer AGCTCGCGTGTATTTGGAAG; 3′ primer ACCACCGGCAGAACATACAG, 573 bp product). Each primer set was designed to ensure that primer binding occurred both inside and outside the original integration cassette. PCR analysis was performed as recommended by the Taq DNA polymerase manufacturer (New England Biolabs). Antibiotic Susceptibility Assays. [0026] The ability of the reporter phage to confer a bioluminescent signal to S. flexneri in the presence of ciprofloxacin or ampicillin (Sigma Aldrich) was compared to the Clinical Laboratory Standards Institute (CLSI) broth microdilution method. Cells (5×10 5 CFU/mL) and antibiotics were prepared in cation-adjusted Mueller Hinton broth according to CLSI methodology. Cells were incubated with ampicillin (0.06 to 8 μg/mL) or ciprofloxacin (0.0005 to 0.12 μg/mL) in microtiter plates, incubated at 35° C., and assessed for growth (A 625 ) after 20 h as per the CLSI protocol. The MIC using the internal QC strain E. coli ATCC 25922 for ampicillin and ciprofloxacin was 2 and 0.015 μg/mL, respectively, both within the acceptable range. The same Shigella inoculum was grown for 5 h at 35° C. in the presence of antibiotics, infected with Shfl::luxAB, and bioluminescence assayed after 20 min. [0000] Detection of S. flexneri in Spiked Stool Samples. [0027] Human stool samples from healthy individuals were sterilized by autoclaving, and spiked (10 μL) with S. flexneri (10 3 -10 6 CFU/g). Stool samples (n=3 each for both the no-cell control and spiked samples) were processed by mixing with 9 mL of LB, vortexing vigorously for 5 s, and incubating at 37° C. with aeration. After 4 h, aliquots were infected with Shfl25875::luxAB and analyzed for bioluminescence. Bioluminescence Assays. [0028] Unless otherwise stated, Shfl25875::luxAB (3×10 8 PFU/mL final) and cells were mixed and incubated at the designated temperatures for set times. ‘Flash’ bioluminescence was measured using a luminometer. Cultures (195 μl per reading) were injected with n-decanal and read. Controls consisted of both cells alone and phage alone. Bioluminescence is depicted as relative light units (RLU) and the data presented are the average of three experiments SD unless otherwise stated. Statistical significance was determined using Student's t-test (p<0.05). [0000] Isolation of Phages with a Broad S. flexneri Tropism. [0029] S. flexneri serotype 2a is responsible for the majority of shigellosis worldwide. In addition, the occurrence of drug-resistant isolates for the epidemic S. dysenteriae serotype 1 is increasingly common. Phages were therefore isolated using S. flexneri serotype 2a, and S. dysenteriae serotype 1 as hosts. Over 100 phages displaying differences in plaque morphology (size, turbidity, clarity), titer, and stability were isolated and were then screened for host range against various S. flexneri serotypes and S. dysenteriae serotype 1. The vast majority of phages displayed a narrow host range; able to grow on the serotype used for isolation, but exhibited a reduced efficiency of plating (eop) on other serotypes (data not shown). However, one phage (named Shfl25875) grew on 28/29 of S. flexneri and all twelve S. dysenteriae type 1 strains with an eop of >0.1, and displayed an inability to grow on non- Shigella spp. (Table 1, and data not shown). Shfl25875 produces clear ˜3 mm plaques on S. flexneri ATCC 25875 and normally yields titers of >10 10 PFU/mL in plate stocks. No significant loss in titer was noted after storage for 8 months at 4° C. Shfl25875 was therefore selected for further characterization, including genome sequencing and reporter phage development. [0000] TABLE 1 Shigella inclusivity host range analysis with Shfl25875 Number of strains Species Serotype infected/total tested S. flexneri 1a 2/2 S. flexneri 1b 1/1 S. flexneri 2a 16/16 S. flexneri 2b 1/1 S. flexneri 3 1/1 S. flexneri 4 3/3 S. flexneri 5 1/1 S. flexneri 6 1/2 S. flexneri Y 1/1 S. flexneri Unknown 1/1 S. dysenteriae Type 1 12/12 “Infected” defined by having an efficiency of plating of >0.1 relative to host strain S. flexneri Genome Analysis. [0030] Assembly of the Ion-Torrent output sequence of the Shfl25875 genome generated a single contig of 169,062 bp. The closest match in GenBank is RB69 (GenBank AY303349.1), a 167,560 bp coliphage genome with which Shfl25875 shared ˜97% sequence identity. RB69 is a member of the Tevenvirinae and is thus a T4-like phage, and homologs of all known essential, and most characterized non-essential genes of RB69 are both present in and syntenic with Shfl25875. The major differences are that Shfl25875 encodes a putative internal head protein IpII, which is present in only some members of the T4-like phages, and a putative segD-like homing endonuclease, a type of element common to many T4-like phages, but completely lacking in RB69. It also contains two orfs between cd and cd.2, one of which codes for a protein of the AroG superfamily, with 69% similarity to S. dysenteriae phospho-2-dehydro-3-deoxyheptonate aldolase. Conversely, Shfl25875 lacks the RB69 protease-inhibitor gene pin. The most closely related phage whose host is described as S. flexneri is Shfl2 (GenBank HM035025.1) with ˜80% sequence identity to Shfl25875. The long tail fibers, responsible for initial Shfl25875 adsorption to S. flexneri are, however, more similar to certain T4-like coliphages than to Shfl2. [0000] Integration of the luxAB Reporter into the Phage Genome. [0031] LuxAB was inserted into the phage genome by homologous recombination without deleting any phage DNA. The genome size of Shfl25875::luxAB is thus 2,108 bp greater than its parent phage Shfl25875. The inserted DNA reduces the length of the terminal redundancy associated with all T4-like phage genomes; redundancy in the T4 genome was estimated at ˜5 kb, and assuming a comparable length for Shfl25875, luxAB insertion causes a 40% reduction. However, no significant growth defect of Shfl25875::luxAB has yet been noted (see below). PCR was used to verify the presence of luxAB in the recombinant phage, and that it had integrated correctly into the targeted site ( FIG. 2 ). PCR of phage lysates using primers designed to amplify a portion of luxB, and separately, to span the 5′ and 3′ junctions of luxAB when integrated into the phage genome, generated the expected size PCR products. [0032] A one step growth curve compares the fitness of Shfl25875::luxAB to its parent. Both phages exhibit similar growth profiles ( FIG. 3 ), including a 25-30 min latent period and average burst size (90 and 76, respectively for Shfl25875 and Shfl25875::luxAB) typical values for T4-like phages. These data further show that insertion of luxAB into Shfl25875 did not negatively affect fitness. [0000] Shfl25875::luxAB-Mediated Detection of S. flexneri. [0033] The reporter phage transduces bioluminescence to S. flexneri within 20 min of infection ( FIG. 4 ). A significant increase in signal resulted, indicating that Shfl25875::luxAB expresses luxAB at significant levels soon after infection. The signal reaches its maximum level by approximately 60 min, and incubation for more than 120 min resulted in a drop in signal. Sensitivity limits of detection using serial dilutions of S. flexneri show dose-dependent characteristics, with increasingly higher number of cells displaying proportionally higher signals ( FIG. 5 ). The limit of detection was approximately 10 2 CFU/mL within 60 min of infection (p<0.05). Collectively, the data indicate that Shfl25875::luxAB rapidly transduces a strong bioluminescent phenotype to S. flexneri in pure culture. Inclusivity and Specificity of the Reporter Phage. [0034] We determined whether Shfl25875::luxAB could transduce a signal response to all four Shigella species, to closely related non- Shigella Enterobacteriaceae ( E. coli, S. enterica, Y. enterocolitica, K. pneumoniae ) and to more distantly related but clinically relevant enteric pathogens ( B. cereus, L. monocytogenes ) (Table 2). Shfl25875::luxAB detected 28/29 S. flexneri strains of different serotypes and detected 12/12 S. dysenteriae serotype 1 strains. Shfl25875::luxAB also detected 24/27 S. sonnei serotype 1 isolates. Two of 10 E. coli strains (BEI NR-3 and NR-12) elicited signals that were approximately 10- and 100-fold lower than with Shigella but only 1 of 29 strains of other Enterobacteriaceae ( Y. enterocolitica, S. enterica , and K. pneumoniae ) resulted in a positive signal response ( S. enterica strain); this was also 100-fold lower than with the Shigella host strain. As may be expected, the distantly related species B. cereus and L. monocytogenes did not produce signals above background. [0000] TABLE 2 Specificity of Shfl25875::luxAB phage among Shigella species closely related species and non-related but clinically relevant pathogens. Light-positive strains/total tested e Notes Shigella spp. S. flexneri a 28/29 One serotype 6 strain was negative S. dysenteriae b 12/12 All serotype 1 strains S. sonnei 24/27 S. boydii 0/5 Serotypes 1-5 Enterobacteriaceae E. coli c  2/10 2 positive strains 10 to 100- fold lower than S. flexneri K. pneumoniae d  0/10 Background S. enterica 1/9 1 positive strain >100-fold lower signal than S. flexneri Y. enterocolitica  0/10 Non- Enterobacteriaceae B. cereus 0/5 Background L. monocytogenes 0/5 Background a S. flexneri comprising serotypes 1a, 1b, 2a, 2b, 3, 4, 4a, 4b, 5, 6, Y b S. dysenteriae serotypes 2 through 12 only found 2 positive strains out of 12 analyzed (data not shown) c Various O-antigen strains such as O157:H7, O145:H2, O111, O121, and a uropathogenic strain d Including clinical strains isolated from stool and urine e ‘Light positive strains’ defined by phage-infected strains exhibiting a bioluminescence signal response of >10 3 -fold over background controls Rapid Determination of Antibiotic Susceptibility. [0035] A phage-mediated bioluminescent signal response is strictly correlated to cell fitness. Therefore, the ability of Shfl25875::luxAB to confer bioluminescence signal to Shigella spp. in the presence of antibiotics was compared to the standard CLSI broth microdilution method. Standard antibiotics used for determining susceptibility of Shigella isolates include ampicillin and ciprofloxacin. Cells were incubated with a range of antibiotic concentrations in microtiter plates, incubated at 35° C., and assessed for growth (A 625 ) after 20 h as per the CLSI protocol, or bioluminescence following infection by Shfl25875::luxAB. The bioluminescence signal mirrored the growth profile in the presence of ampicillin or ciprofloxacin ( FIGS. 6-7 ). At antibiotic concentrations that had little to no effect on growth, the signal from the reporter phage was near maximum. Conversely, at antibiotic concentrations that were at the minimum inhibitory concentrations (1 and 0.015 μg/mL for ampicillin and ciprofloxacin, respectively) or higher, bioluminescence was at or close to background. However, the CLSI protocol requires 16-20 h to complete while the reporter phage only requires ˜5 h. Shfl25875::luxAB not only diagnoses shigellosis but also simultaneously gathers antibiotic susceptibility data. [0000] Phage-Mediated Detection of S. flexneri in Human Stool. [0036] The standard clinical diagnostic specimen for bacterial dysentery is stool. Whether Shfl25875::luxAB could transduce bioluminescence to S. flexneri in deliberately spiked stool samples was tested. A discernable signal-to-noise level was observed 30 min after infection ( FIG. 8 ). As with pure cultures, Shfl25875::luxAB exhibited typical dose-response characteristics with a sensitivity of detection of 10 3 CFU/g (p<0.05). This level of sensitivity is compatible with clinical samples as Shigella spp. are shed in large numbers during the acute phase of infection. Overview [0037] The isolation of Shigella phages from environmental waters in developing countries where bacterial dysentery is common has been described numerous times in the literature. The selection of the T4-like phage Shfl25875 for diagnostic development was based on its broad host range and its obligate lytic growth characteristic; Shfl25875 plaques on most S. flexneri serotypes and S. dysenteriae serotype 1 strains, but did not grow on most non- Shigella Enterobacteriaceae. That Shfl25875 infects some E. coli strains is not surprising given their very close relationship. Taxonomy places the entire Shigella genus within the species E. coli , and restriction-modification was discovered more than 60 years ago using phages that grow on both E. coli and S. dysenteriae. [0038] In one example, Shfl25875::luxAB elicited a 10 5 -fold increase in bioluminescence to S. flexneri within 20 min. This strong response may be attributed to the position of the reporter within the phage genome. A priori, maximal expression of a phage-carried reporter gene occurs from the strongest promoters. In dsDNA phage genomes, these promoters usually direct expression of the structural genes, which code for proteins that are produced in greatest abundance in the infected cell. However, these promoters are usually activated late in infection, providing only a narrow time window for expression and function of a reporter gene construct. T4 gene 32 is transcribed throughout infection from several promoters, and its protein product acts stoichiometrically on ssDNA generated during phage DNA metabolism. Sequences corresponding to putative middle (mot-dependent) and late promoters were identified upstream of Shfl25875 gene 32, and the gene is followed by a putative terminator, as in T4. Transcriptional regulation of Shfl25875 gene 32 is comparable to that of its T4 counterpart, and thus that luxAB would be expressed at high levels if the cassette was inserted between gene 32 and its transcriptional terminator. This high level expression resulted in a sensitivity limit of detection of 300 CFU/mL in pure culture and ˜10 3 CFU/g of spiked stool, suggesting that further development of Shfl25875::luxAB will result in a valuable diagnostic. [0039] Importantly, simultaneously with diagnosis, Shfl25875::luxAB provides antibiotic susceptibility profiles because the phage uses the host's biosynthetic machinery to elicit bioluminescence. Although empiric antibiotic treatment has traditionally been the routine for shigellosis, this strategy is increasingly problematic due to antibiotic-resistant strains, the epidemic and pandemic S. dysenteriae serotype 1 strain in particular. Resistance to ampicillin, tetracycline, and nalidixic acid and other fluoroquinolones has been observed in various regions of the world. As CLSI protocols for determining antibiotic susceptibility requires 16-20 h, bioluminescence conferred by Shfl25875::luxAB significantly speeds up analysis. A similar strategy has been employed for the identification and drug susceptibility testing of M. tuberculosis isolates using recombinant mycobacteriophages. [0040] There are currently 2 FDA-approved/cleared phage-based diagnostic assays, both of which use wild-type phage and are based on phage amplification; the phage lysis assay for B. anthracis and KeyPath™ Blood Culture Test for identifying Staphylococcus aureus and differentiating MRSA and MSSA. Alternative Insertion Location. [0041] Targeted insertions between the scaffolding protein gene and major capsid protein gene were also attempted. The rationale is that the major capsid protein is the most abundant phage protein made after infection, and thus that mRNA levels in this region of the genome are also likely high. In a recombinant phage, luxAB are thus also to be expected to be highly transcribed. Inserted DNA fragments included a duplication of the late promoter sequence (TATAAATA), in order to ensure adequate transcription of the downstream gene 23; the late promoter and the complete natural intergenic sequence between genes 22 and 23, in case that short sequence was important for gene 23 expression. PCR of DNA found in lysates indicated that the expected recombination between the phage and the luxAB plasmids had occurred but luminescent phages were not found. As adequate numbers of plaques were screened, the reason for this failed attempt is unknown but may be hypothesized that the luxAB insert was deleterious because the amounts of gp22 (scaffold) and gp23 (capsid) actually synthesized in a recombinant phage was imbalanced, causing interference with the phage assembly process. Alternative Phages Sdys9752 and Sdys12039 [0042] The previous examples isolated, characterized, and genetically engineered a Shigella phage named Shfl25875 which could be used for the detection of certain Shigella bacterial strains. The Shigella genus is classified by four serogroups: S. dysenteriae (15 serotypes); S. flexneri (six serotypes); S. boydii (19 serotypes); S. sonnei (1 serotype). While the Shfl25875 phage infected many Shigella serogroups, it did not infect them all. Two additional phages, named Sdys9752 and Sdys12039, were also developed using similar techniques to those previously described with respect to Shfl25875. These alternative phages complement the strains of Shigella infected by Shfl25875. For example: [0043] 1. Shfl25875 infects the majority (28 out of 29) of S. flexneri strains. The one Shfl25875-resistant strain is susceptible to Sdys9752. [0044] 2. Shfl25875 infects all (12/12 strains) S. dysenteriae type 1 strains, but shows poor infectivity (2 out of 12) against the other S. dysenteriae types (2 through 12). In contrast, Sdys9752 does not infect type 1 strains, but infects 5 of 12 type 2-12 strains. In addition, Sdys12039 infects 9 of 12 S. dysenteriae type 2-12 strains. In combination, these 3 phages infect nearly all (22/24) S. dysenteriae strains tested. [0045] 3. Shfl25875 infects 24 out of 27 S. sonnei strains tested. The three Shfl25875 resistant S. sonnei strains are susceptible to either or both of Sdys9752 and Sdys12039. [0046] 4. Shfl25875 does not infect the 5 S. boydii strains in our collection. However, Sdys9752 and Sdys12039 infects 4 out of 5 of these strains. [0047] The Sdys9752 and Sdys12039 phages were molecularly engineered to generate reporter phages using techniques that were similar to that described for Shfl25875. In both cases, the luxAB reporter genes were inserted into non-coding regions of the genomes by homologous recombination without removing any phage DNA and thus increased the overall genome sizes by 2,108 bp. PCR analysis was used to verify the presence of luxAB in the recombinant phages, and that luxAB had integrated into the correct predicted site in the phage genome (data not shown). PCR analysis of phage lysates using primers designed to amplify a section of luxB, and to span the 5′ and 3′ junctions of luxAB integration into the phage genomes, generated the correct sized PCR products as expected. This indicated: (i) the presence of the reporter, and (ii) that the luxAB cassette had integrated at the correct genome sites as expected. [0048] The ability of Sdys9752::luxAB and Sdys12039::luxAB to transduce a bioluminescent phenotype, and hence detect Shigella strains was analyzed (results shown in FIGS. 9-10 ). As shown in FIGS. 9-10 , S. sonnei 9290 and S. flexneri 7-3510 were grown at 37° C. in LB broth, and mixed with Sdys9750::luxAB or Sdys12039::luxAB, respectively. Infected cultures were incubated at 37° C. and bioluminescence was measured over time following the addition of substrate n-decanal. Numbers are the mean (n=3)±SD. Reporter phage (10 8 PFU/mL final) and cells were mixed and ‘flash’ bioluminescence was measured following the addition of the substrate decanal using a GLOMAX® 96 Microplate Luminometer (registered trademark of Promega Corporation of Madison, Wis.). Strong (10 5 -fold increase in signals over background) and rapid signals were detected 20 min after infection with both reporter phages. These data indicating that the reporters were able to infect, and express luxAB to significant levels in a very short period of time. Similar results were obtained with other Shigella strains. [0049] The current configuration of the detection device requires the addition of an aldehyde substrate (e.g., n-decanal) in order to generate the bioluminescent signal response. In this configuration, the luciferase enzyme (encoded by luxAB) in the presence of flavin mononucleotide (naturally present in the bacterial cell), oxygen and endogenously added decanal, catalyzes the reaction resulting in light as a by-product. In another configuration, the phage is engineered to encode the genes encoding luciferase, as well as the genes encoding the fatty acid reductase complex. These latter genes (luxCDE) encode the enzymes required for making the substrate, and thus generates an inclusive detection system that does not require exogenous substrate for light production. [0050] The previous examples discuss using the disclosed technology in a laboratory setting to test human stool samples. It is understood that one of ordinary skill in the art would be able to adapt the disclosed technology for use in other settings such as in the field to test for the presence of target bacteria such as members of the Shigella genus. It is also understood that the disclosed technology could be adapted to test other materials such as other human clinical samples (mucus, rectal swabs, and the like), drinking water, food, soil, surfaces, and the like. In other examples, the phages described herein may be included as part of a Shigella microorganism detection kit having sample(s) of the phages described herein stored in suitable container(s) packaged with one or more testing containers for collecting and testing samples to be tested for the presence of Shigella microorganism. [0051] While the claimed technology has been illustrated and described in detail in the drawings and foregoing description, the same is to be considered as illustrative and not restrictive in character. It is understood that the embodiments have been shown and described in the foregoing specification in satisfaction of the best mode and enablement requirements. It is understood that one of ordinary skill in the art could readily make a nigh-infinite number of insubstantial changes and modifications to the above-described embodiments and that it would be impractical to attempt to describe all such embodiment variations in the present specification. Accordingly, it is understood that all changes and modifications that come within the spirit of the claimed technology are desired to be protected.

4y

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is directed to a cardiac lead suitable for use in pacemakers, cardioverters, defibrillators, and the like, as well as to a method and circuit for using such a lead to detect cardiac rhythm abnormalities, such as fibrillation and tachycardia. 2. Description of the Prior Art A cardiac lead typically has a proximal end with a connector adapted for electrical and mechanical connection to a cardiac-assist device, such as a pacemaker, cardioverter or defibrillator, and an opposite distal end, at which one or more electrodes is/are located. Between the distal end and the proximal end, the lead has a flexible insulating sheath or jacket, containing one or more conductors, depending on the number of electrodes. The electrodes are exposed conductive surfaces at the distal end of the lead. Conventional electrode configurations include a unipolar configuration and a bipolar configuration. In a unipolar configuration, there is only one electrode at the distal end, typically a hemisphere covering the distal tip. Typically the housing, or a portion thereof, of the cardiac assist device is used as the indifferent or return electrode. A bipolar lead has two electrode surfaces, separated from each other by a slight spacing. Typically one of these electrodes is formed as a hemispherical electrode at the distal tip of the lead, and the other is a ring electrode, which annularly surrounds the sheath, located a short distance behind the tip electrode. In most modern cardiac assist devices, the electrode lead is not only used to deliver an appropriate cardiac assist regimen in the form of electrical pulses, but also is used to detect cardiac activity. The detection of cardiac activity can serve many purposes, such as for use in determining whether adjustments to the cardiac assist regimen are necessary, as well as for identifying cardiac rhythm abnormalities which may require immediate preventative action, such as the occurrence of tachycardia or fibrillation. Particularly in the case of a cardioverter or a defibrillator, which is normally passive unless and until tachycardia or fibrillation is detected, it is important not only to reliably detect tachycardia or fibrillation when they occur, but also it is important not to misidentify a non-emergency cardiac rhythm abnormality as tachycardia or fibrillation, since administering the emergency regimen to a healthy heart can possibly create an emergency situation where none exists. Moreover, at least in the case of a defibrillator, unnecessary triggering of the extremely strong defibrillation energy will cause considerable discomfort to the patient. An electrode lead for a cardiac pacemaker is disclosed in U.S. Pat. No. 5,306,292 which has a distal tip with a number of closely spaced electrodes thereon, with the remainder of the hemispherical surface of the distal tip of the electrode being non-conducting. Circuitry in the pacemaker housing, connected to the respective electrodes via the electrode lead cable, allows the total conductive area and geometry of the distal tip of the electrode lead to be selectively varied, by activating the electrodes in different combinations. For example, the combination of electrodes (i.e. conductive surfaces) at the electrode tip which provides the lowest stimulation threshold can be determined by an autocapture unit, so that energy consumption can be reduced. Many algorithms are known for analyzing the detected signal wave forms obtained with unipolar and bipolar leads. A prerequisite to the proper functioning of most of these algorithms is that the signal which enters into the algorithm be relatively noise-free. The detected signal, in its raw form, can be corrupted by noise produced by electromagnetic interference in the patient's environment, as well as by muscle activity. Such noise may mimic a fibrillation pattern, for example, particularly in the case of a unipolar lead, but also to a certain extent with a bipolar lead. Conventional noise-removing techniques involve filtering and other types of signal editing procedures. After making the incoming signal reasonably noise-free, conventional detection algorithms analyze the signal by undertaking one or more threshold comparisons and/or by analyzing the rate of occurrence of a particular characteristic of the signal (i.e., maxima, minima, zero crossings, etc.) over a given period of time. Comparison of the signal waveform to stored signal templates, respectively representing previously-obtained abnormal signals, is also a known technique. In this manner, a determination is made as to whether the incoming signal represents normal sinus rhythm, a PVC, tachycardia, atrial fibrillation, ventricular fibrillation, etc. SUMMARY OF THE INVENTION It is an object of the present invention to provide a method and a circuit for analyzing signals obtained with a cardiac lead having a multi-electrode tip for the purpose of detecting cardiac abnormalities so that remedial action can be taken. The above object is achieved in accordance with the principles of the present invention in a first embodiment of a method and circuit for analyzing unipolar signals obtained from respective dot-like electrodes disposed at the distal tip of a cardiac lead, which are simultaneously in contact with cardiac tissue, wherein time-related differences between two or more of the unipolar signals are analyzed, and the result of this analysis is used to detect whether a cardiac rhythm abnormality exists. These time-related differences exhibited by the unipolar signals from the dot-like electrodes arise because even though the electrodes are very close together, the speed of the depolarization of the cardiac tissue is not negligible compared to this distance. However, for a specific patient and a specific location of the multi-dot lead, the same time differences between unipolar signals will occur for each heartbeat during normal sinus rhythm. During tachycardia or fibrillation, the speed and direction of the propagating depolarization will be different giving rise to another time difference pattern. The respective unipolar signals from the dot-like electrodes each exhibit a morphology that is virtually identical from electrode-to-electrode. The fact that the morphologies of the respective unipolar signals are virtually identical is exploited to identify a time shift or time offset of one unipolar signal relative to the other. In one embodiment, this time offset is used to create a delayed difference signal which will be zero or close to zero, during normal sinus rhythm, but exhibit a higher amplitude during tachycardia or fibrillation due to a different depolarization speed and direction. If and when the amplitude of the delayed difference signal, filtered or not, exceeds a threshold level, a cardiac rhythm abnormality is indicated. In another version of the first embodiment of the inventive method and circuit, two or more of the unipolar signals are correlated with each other. Again since the morphologies of two signals is more or less identical except for the shift in time, the time delay between signals can easily be determined using e.g. correlation. When this time difference, as determined by this analysis, deviates too much from what is considered normal it is taken as an indication of an existing cardiac rhythm abnormality. For a given patient, values for the absolute value of the time shift can be identified and stored which are respectively indicative of tachycardia and fibrillation, so that the two can be distinguished from each other by analysis of the time offset, and thus an appropriate signal can be emitted to initiate different types of appropriate remedial action. Similarly, different values for the correlation result can be obtained and stored, respectively indicative of tachycardia and fibrillation. In a third version of the first embodiment, the sequence of arrival of the unipolar signals at the respective dot-like electrodes is forming a pattern, and the existence and/or type of cardiac rhythm abnormality is identified dependent on this pattern. In a second embodiment of the inventive method and circuit, the unipolar signals are surveyed, via a telemetry link, by a physician operating an external programming device, and the physician selects a heartbeat which the physician believes best represents a particular type of cardiac activity, including different types of cardiac abnormalities. The pattern of the sequence of the selected unipolar signal detections is stored as a template, and subsequently obtained unipolar signal detections, as occur during daily activity of the patient, are compared to the stored template, such as by undertaking a pattern recognition. Dependent on the similarity of the subsequent unipolar signals to the stored template, the presence of a cardiac rhythm abnormality is detected. The dot-like electrodes of the cardiac lead are individually formed of conductive material, and are separated at the surface of the distal tip of the lead by electrically insulating material. The arrangement of the electrode dots can include a centrally disposed electrode dot, with a number of further of electrode dots annularly arranged around the centrally disposed dot. The annularly arranged electrode dots can be located at radially symmetrical positions relative to the centrally disposed dot. The multiple dots produce respective signals which have features that are slightly offset in time from dot-to-dot so that analysis of these signals can proceed by monitoring the respective offsets. The offsets are represented by relatively easily recognizable wave form features, such as maxima, minima or maximum slew rate. Each electrode dot preferably has a diameter of 0.5 mm, with the edge-to-edge distances among all of the respective dots being approximately equal. A heart cell is about 0.02 mm wide and approximately 0.1 mm long. This means that one electrode dot will cover a large number of heart cells. When a propagating wave front passes the multiple dots, the coupled heart cells are activated in sequence. This means that the signals registered by each dot electrode in a unipolar fashion will “see” similar pulse shapes (wave forms), but with small time offsets from dot-to-dot. During normal wave propagation, the heart cell excitations follow a relatively synchronized and coordinated pattern. Such a pattern, however, is not present during fibrillation. Even for the small area in contact with the distal tip of the lead, there will be disorganized electrical activity registered by the respective dots. By obtaining individual signals for each electrode dot, and then analyzing these signals as a group, conclusions can be made as to whether normal sinus activity is present, or some type of cardiac abnormality. In accordance with the invention, one appropriate method for analyzing the signals obtained from the respective electrode dots is to obtain unipolar signals from the respective dots with the cardiac assist housing serving as the ground level. By comparing a difference between respective signals from two dots, a bipolar signal is obtained, although this will be different from a conventional bipolar signal obtained with a tip electrode and a ring electrode configuration. Multiple difference signals are thus available for analysis, and it is also possible to employ one of the electrode dots as a reference, and to refer all of the difference signals to the signal obtained from that one dot. DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic end view of the tip of an electrode lead, in an embodiment heading seven electrode dots, in accordance with the principles of the present invention. FIG. 2 is a block diagram showing the basic components of an implantable cardiac assist device, constructed and operating in accordance with the principles of the present invention. FIG. 3 illustrates the unipolar signal from the centrally disposed electrode dot in the embodiment of FIG. 1 . FIG. 4 illustrates respective difference signals between the centrally disposed electrode dot and other electrode dots, in accordance with the invention. FIG. 5 is a block diagram of an embodiment for the block labeled “Heart Beat Identification” in FIG. 2 . FIG. 6 illustrates input signals from the electrode dots in the embodiment of FIG. 1 . FIG. 7 illustrates the output pulses for the intracardial signals shown in FIG. 6 . FIG. 8 illustrates the detector pulse pattern for the fourth beat in FIG. 7 . FIG. 9 illustrates the detector pulse pattern for the fifth beat in FIG. 7 . FIG. 10 is a block diagram of an embodiment of the pattern recognition unit of FIG. 5 . FIG. 11 illustrates results from the pattern recognition unit, and one input signal. DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of an electrode lead for use with the circuit and method in accordance with the principles of the present invention is shown in FIG. 1 , which is a view looking directly at the distal tip (greatly enlarged) of the cardiac lead. As can be seen in FIG. 1 , the lead tip has a number of electrode dots distributed thereon, including a centrally disposed electrode dot 1 and a number of other electrode dots arranged relative to the centrally disposed electrode dot 1 . In the embodiment of FIG. 1 , six other electrode dots 2 - 7 are shown, for a total of seven electrode dots in the embodiment of FIG. 1 . In the embodiment of FIG. 1 , the electrode dots 2 - 7 are shown as being annularly arranged around the centrally disposed electrode dot 1 , however, other locations are possible. The axes shown in FIG. 1 are in arbitrary units and are solely for the purpose of providing a guide as to the relative placement of the electrode dots 1 - 7 . Each electrode dot will have a diameter of approximately 0.5 mm. The lead tip shown in FIG. 1 is at the distal end of a flexible, implantable electrode lead (schematically shown in FIG. 2 ), having an opposite end with a plug adapted to be fitted into a cardiac assist device, such as a pacemaker, cardioverter or defibrillator. The lead will contain respective conductors for the electrode dots 1 - 7 , each conductor being insulated from the others and the entire lead being jacketed in an insulating sheath, as is standard. The surface of the electrode tip surrounding the respective electrode dots 1 - 7 is composed of insulating material, so that the electrode dots are electrically insulated from each other. In practice, a unipolar signal is obtained from each of the electrode dots 1 - 7 , i.e., seven unipolar signals are obtained. These unipolar signals can be analyzed by time offsets (shifts) differences between the respective unipolar signals from any two of the electrode dots. The reasons why these time effects exist is as follows. The depolarization of heart cells can be considered as being represented by a propagating wavefront. If the wavefront is assumed to be propagating from right to left in FIG. 1 , with the respective unipolar signals from the electrode dots 1 - 7 being sampled as the wavefront propagates, the wavefront will arrive later at electrode dot 5 , for example, than at electrode dot 1 , because the distance between the electrode dots is not negligible relative to the propagation speed of the wavefront and the sampling frequency. There will be no offset, for example, between arrival at the wavefront at electrode dots 3 and 7 , or arrival of the wavefront at electrode dots 4 and 6 . As an example, assume that the unipolar signal from electrode dot 5 is offset or shifted 1 ms (or 5 samples, if the sampling frequencies is 5 kHz) compared to the unipolar signal from electrode dot 1 . The respective waveforms of the unipolar signals from electrode dots 1 and 5 are basically the same in appearance, but as a generalized statement the unipolar signal from the electrode dot 5 will be shifted by 5 samples relative to the unipolar signal from the electrode dot 1 . Therefore, the time difference between a sample at a given time t in the unipolar signal obtained from the electrode dot 5 , and a sample at time t− 5 in the unipolar signal obtained from dot 1 , will be 0. If the wavefront comes from a different direction, however, and the difference between the samples at these times in the two unipolar signals is calculated, the difference signal will not be 0. Thus, for every combination of pairs of electrode dots and direction of propagation of the wavefront, there is a time delay associated with that combination, corresponding to a distinct number of samples. In other words, if it is necessary to delay (shift) one of the unipolar signals by this distinct number of samples before creating a bipolar signal with another unipolar signal, a minimum signal is obtained. The number of samples by which it is necessary to shift one of the unipolar signals relative to the other is determined by calculating the correlation between these two unipolar signals for different time shifts. Shifting one of the signals by the aforementioned distinct number of samples will yield the highest correlation result. Since the calculation of the correlation includes several multiplications, which is time consuming as well as imposing processor demands, alternatively the sum of the absolute differences between the two signals can be calculated. A shift of one signal relative to the other by the aforementioned distinct number of samples will generate the smallest sum of absolute differences. In order to use the difference signals as an analysis tool for identifying cardiac abnormalities, it must be identified which delay, for a given pair of dots, occurs as a result of normal sinus rhythm, wherein the wavefront is propagating from a specific direction most of the time. If and when fibrillation occurs, due to the chaotic electrical activity of the cardiac tissue, the wavefront will propagate from different directions, and the departure of the delay from the delay which has been identified as representing normal sinus rhythm can be used as an indicator of the onset of fibrillation. In general, the procedure for analyzing the unipolar signals from a pair of electrode dots is as follows. The delay associated with a pair of electrode dots during normal sinus rhythm is identified, such as by correlation or another suitable technique. This delay can be denoted as delay. During operation of the cardiac assist device, a delayed difference signal is continuously calculated, such as x 1 (t)−x 2 (t−d), instead of the undelayed difference signal x 1 (t)−x 2 (t), wherein x 1 and x 2 represent the respective unipolar signals from two electrode dots in the pair under consideration. If the delayed difference signal, with appropriate filtering, if necessary, is larger than a threshold value, an episode of non-sinus rhythm is assumed to exist. The threshold value can be a predetermined value or can be adapted as data are accumulated. As noted above, what is really being detected using the electrode lead shown in FIG. 1 is whether the propagating wavefront is arriving from a direction different from that which occurs during normal sinus rhythm. This change in direction, in addition to arising from an episode of fibrillation, could arise due to a premature ventricular contraction (PVC), or due to slight dislodgement of the lead. As explained below, by appropriate filtering and/or decision algorithms, the false detection of a PVC as ventricular-fibrillation can be eliminated. The probability of lead dislodgement becomes negligible after a period of time following implantation. It is recommended to periodically reinitialize the delay factor, i.e. to re-identify the delay associated with normal sinus rhythm at predetermined intervals, or when the delayed difference signal has slowly changed by more than a predetermined percentage. The basic components of an implantable cardiac assist device in accordance with the invention are shown in FIG. 2 . The implantable cardiac assist device can be a pacemaker, a cardioverter or a defibrillator, for example. The implantable cardiac assist device has an input stage including amplifiers and filters, to which respective conductors, together forming a cardiac lead, from the electrode dots 1 - 7 are supplied. The unipolar signals from the electrode dots 1 - 7 are supplied to a heart beat identification stage as well as to main circuitry in the cardiac assist device. The functioning of the heartbeat identification stage will be described below, in several embodiments. The main circuitry is whatever type of circuitry is appropriate for the cardiac assist device, and can include pacing logic if the device is a pacemaker, or defibrillation circuitry if the device is a defibrillator. The appropriate cardiac assist therapy is generated in a known manner by the main circuitry and is delivered to the patient either through the aforementioned electrode lead or another appropriately designed electrode lead. The main circuitry, therefore, is conventional, except that it responds to a heartbeat identification signal produced in accordance with the invention. The main circuitry is also in communication with a telemetry unit, which wirelessly communicates with an external programmer in a known manner for reading out patient data and for making changes in the operating parameters of the implantable cardiac assist device, as needed. Based on the unipolar signals from dots 1 , 2 , 3 and 4 , the time difference between dots 1 and 2 , dots 1 and 3 and dots 1 and 4 as a function of time is calculated using correlation. A portion of a predetermined length, i.e., the window length, of the signals from dot 1 and dot 2 is selected. The window length may be one second, for example. The correlation between the two signal portions of the respective unipolar signals is then calculated and stored. The signal from dot 2 is then shifted by one sample compared to the signal from dot 1 , and the correlation is again calculated and stored. The window is then shifted two samples from the original position, and a new correlation is calculated and stored. This process is repeated for a predetermined number of shifts of the window, both positive and negative. The shift producing the highest correlation is the delay between the two dots in question. As described above, alternatively the sum of squares of the signal differences can be used, in order to avoid the time and complications associated with correlation calculations. In this alternative embodiment, a minimum should be sought. As time progresses, the process is repeated, so that a plot of the time difference compared to the center dot arises as a function of time. This is shown in FIG. 4 . The same algorithm as described above was used for determining the time difference between dots 1 and 3 and dots 1 and 4 . As can be seen in FIG. 4 , the time delay or time difference is constant during normal sinus rhythm and varies during fibrillation. A varying time difference between a pair of dots is thus a major indication of fibrillation. The time difference signal, after filtering, differentiation or some other manipulation, can be employed in combination with a threshold level to detect fibrillation. An embodiment of the heartbeat identification stage of FIG. 2 is shown in FIG. 5 . In this embodiment, signals obtained from the electrode dot lead are supplied to a QRS detector. These signals are supplied from the QRS detector to a pattern recognition unit as well as to a template collector. The template collector, through the main circuitry and the telemetry link, is in communication with the external programmer. Signals from the electrode dot lead continuously arrive via the QRS detector at the template collector and are fed into a shift register. Via the telemetry link, a physician who is monitoring the heart activity can freeze the contents of the shift register when a representative beat of the type which is intended to be stored as a template is present. Otherwise, the signals proceed through the shift register and are not stored or prevented from entering said shift register. When the physician recognizes a signal displayed at the programmer of the type which the physician wishes to store, the physician operates the programmer to cause that signal to be stored in the template memory. As an example, input signals from the electrode dots 1 - 7 obtained during the occurrence of a PVC are shown in FIG. 6 . The PVC occurs in the middle of FIG. 6 . FIG. 7 shows the detector pulses from the output of the QRS detector for the signals shown in FIG. 6 . There are no distinguishable patterns which are visually apparent from FIG. 7 , but if pulses from the signals from the electrode dots 1 - 7 are obtained and analyzed as described above, reliable detection can be made as shown in FIGS. 8 and 9 . The detector pulse pattern for the fourth beat in the signals shown in FIG. 6 is shown in FIG. 8 . The pulse pattern for the next beat (the fifth beat), which is a normal beat, is shown in FIG. 9 . When analyzed in this manner, the difference is readily apparent. Details of an embodiment for the pattern recognition block of FIG. 5 are shown in FIG. 10 . The input signals IN 1 -IN 7 are the pulses of the type shown in FIGS. 8 and 9 . These pulses are respectively supplied to shift register 1 -shift register 7 and the outputs of these shift registers are supplied to a reshaping unit. The pattern recognition unit is also supplied with two further inputs IN 8 and IN 9 , which respectively represent the QRS template and the PVC template, stored in the template memory. The clock signal (not shown) for operating these shift registers is the same as was used to generate the stored templates, i.e., the clock signal that was used to feed the signals from the QRS detector to the template collector. This is necessary so that a direct correspondence will exist between the now-detected signals and the stored templates. The output of the reshaping unit is supplied to each of two dot product forming stages (“dot product” meaning the vector dot product). These dot product forming stages are respectively are supplied with the QRS and PVC templates. By forming the respective dot product of these templates, in vector form, with the vector formed by the inputs IN 1 -IN 7 in the reshaping unit, an indication of whether normal QRS activity is present or whether a PVC is present is obtained. Instead of using a dot product, other possible techniques are convolution and cross-correlation. FIG. 11 shows representative signals in the circuit shown in FIG. 10 . The top signal is one of the input signals to the QRS detector, the middle signal is the output of the QRS level detector, and the bottom signal is the output of the PVC level detector. Although modifications and changes may be suggested by those skilled in the art, it is the intention of the inventors to embody within the patent warranted hereon all changes and modifications as reasonably and properly come within the scope of their contribution to the art.

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This application is a continuation of application Ser. No. 08/110,213, filed on Aug. 23, 1993, which is a continuation of 07/915,385, filed on Jul. 20, 1992, which is a continuation of 07/614,577, filed on May 1, 1990, which is a continuation of 07/096,307, filed on Sep. 8, 1987, now abandoned. BACKGROUND OF THE INVENTION Pads of round or polygonal shape made of cotton mat or similar material have become common articles in hygiene, cosmetics, and medicine. The products available previously on the market, while they were satisfactory in terms of absorbency and softness, had the undesirable tendency to lose fibers, so that fibers of the batting remained on the skin. It has already been proposed that this disagreeable feature be eliminated by mixing thermoplastic fibers with the cotton or similar fibers and fusing them at various points to the outer surface of the cotton pad (European Patent 0 124 834). European Patent 0 135 404 also proposes that the fibers in the cotton web be firmly held in the interior of the web as well, by what is known as "hydraulic wrapping", in such a way that they can no longer readily come loose. Finally, it is known from German Utility Model 85 33 322 that a swab, made of cotton and/or viscose fibers, may be made by adding synthetic melting fibers to it, which are distributed over the entire volume of the tip and are joined to the fibers adjoining them by means of an at least superficial pressure-free fusion process. SUMMARY OF THE INVENTION The present invention now makes it possible in a simple and economical manner to produce "tailor-made" pads that suit various purposes and can be adapted to the various wishes of the consumer. The pads according to the invention, which are intended in particular for applying and/or absorbing liquid or semi-solid substances such as cosmetic, pharmaceutical and biological fluids, salves, exudates, and so forth, as well as technical substances of every kind, have at least two plies, at least one layer being absorbent and both outer layers being compressed. Preferably they have a compressed surface layer on both sides with an approximately uncompressed or only slightly compressed and fully absorbent intermediate layer. The compression may be to an equal extent on both outer surfaces, or to different extents; in either case, however, it prevents lint formation, that is, the undesirable escape of individual fibers, and what is known as "powdering." For example, a liquid or cream can be applied without a great amount thereof penetrating the pad and thus being wasted. A lesser Compression on the back of the same pad, on the other hand, makes it possible to remove any excess substance applied, such as cleansing cream, simply by turning the pad over; the less-compressed and therefore more-absorbent outer surface does not present any problems at all in terms of absorption. Optionally, at least one layer contains a cosmetic or medically active ingredient. DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS The compression of the outer surfaces is generally effected by calandaring, and more closely- or widely-spaced embossed patterns can also be selected as needed. Depending on the material, the calandaring is generally peformed preferably at 100° to 200° C. at a pressure of up to 0.5 kg/cm 2 , with a roller speed of 5-25 m/min. If up to 10% of the surface area is embossed, the result is an absorbent material that is suitable for absorbing fluids. With an increasing proportion of embossed surface area, the surface becomes less and less absorbent; the recessed portions of the embossed pattern can additionally serve as a kind of reservoir, while the raised areas can serve as the absorbent cushion. The compression can also be accomplished with the aid of chemical substances, such as physiologically unobjectionable air- and moisture-permeable synthetic resins that do not irritate the skin, with which the outer surface is treated to a variable extent as needed. Such resins are known to one skilled in the art for producing various articles of batting of wadding suitable fiber materials include cotton, viscose, synthetic fibers, or mixtures of these. For producing the cotton pads according to the present invention, the procedure is, for example, as follows: Preparation of the fibers to make the card web is done in the usual manner, for example on carding, card brushing or similar suitable machines. Next, the card web is combined into at least three continuous card web faces having the desired total weight, and then the embossing of the first and second card web face with the patterns that are desired and are needed for the particular intended use is performed in a known manner. The three (or more) card web faces are then put together to form a structure of alternating embossed and uncompressed layers- The web-like structure thus obtained is now stamped or cut into the desired shape and packed in a suitable manner. Depending on the intended use, a further treatment, such as sterilization, impregnation with active ingredients, and so forth, can also be performed before or after the web is cut to size. This process makes it possible to use conventional equipment, and products having a smooth, fiber-free, non-powdering yet still soft outer surface and an absorbent closed-edge seam are produced. However, production can also be done with known machines by aerodynamic or hydrodynamic methods. If desired, the compressed outer surface layers can have further slightly compressed layers placed in between them, to increase the absorbency of the products. A round pad for cosmetic purposes, having a thickness of approximately 3.7 mm, for instance, comprises an uncompressed middle part approximately 1.5 mm in thickness and one compressed upper and lower surface layer each, each of which is approximately 0.8 mm thick. These outer surfaces are both provided with a waffle pattern, one with a very close pattern and the other with a widely spaced pattern of this kind. The product feels very soft and fluffy, but does not become linty or dusty and has excellent absorbency on the coarsely-patterned, less-compressed side. Production is done in the following manner, by way of example: 100% cotton combings, pure and bleached white, are prepared on a carding machine into a carb web. This card web is combineed into three continuous card web faces having a total weight of approximately 350 g/m 2 . Two of these card web faces are separately compressed in an embossing calender and provided with a waffle pattern, which is done at a roller temperature of 150° C., a passage speed of 12 m/min, and a pressure of 1100 kg/20 cm linearly. The three card web faces are then combined into a sandwich-like structure in such a way that the two compressed, embossed faces form the outer surfaces and the third, practically uncompressed face, comes to rest in between these two surfaces. This web of material now travels beneath a stamp, and the desired circles are stamped out, and then stacked into a roll and packed in plastic bags. The foregoing description of the specific embodiments will so fully reveal the general nature of the invention that others can, by applying current knowledge, readily modify and/or adapt for various applications such specific embodiments without departing from the generic concept, and therefore such adaptations and modifications are intended to be comprehended within the meaning and range of equivalents of the disclosed embodiments. It is to be understood that the phraseology or terminology employed herein is for the purpose of description and not of limitation.

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FIELD OF THE INVENTION The invention relates to catalysts useful for olefin polymerization. In particular, the invention relates to “single-site” catalysts that incorporate at least one indenoindolyl ligand. BACKGROUND OF THE INVENTION Interest in single-site (metallocene and non-metallocene) catalysts continues to grow rapidly in the polyolefin industry. These catalysts are more reactive than Ziegler-Natta catalysts, and they produce polymers with improved physical properties. The improved properties include narrow molecular weight distribution, reduced low molecular weight extractables, enhanced incorporation of α-olefin comonomers, lower polymer density, controlled content and distribution of long-chain branching, and modified melt rheology and relaxation characteristics. While traditional metallocenes commonly include one or more cyclopentadienyl groups, many other ligands have been used. Putting substituents on the cyclopentadienyl ring, for example, changes the geometry and electronic character of the active site. Thus, a catalyst structure can be fine-tuned to give polymers with desirable properties. “Constrained geometry” or “open architecture” catalysts have been described (see, e.g., U.S. Pat. No. 5,624,878). Bridging ligands in these catalysts lock in a single, well-defined active site for olefin complexation and chain growth. Other bridged complexes are stereospecific catalysts for α-olefin polymerizations, providing a route to isotactic or syndiotactic polypropylene (see, for example, Herzog et al., J. Am. Chem. Soc . 118 (1996) 11988 and Mansel et al., J. Organometal. Chem . 512 (1996) 225). Other known single-site catalysts replace cyclopentadienyl groups with one or more heteroatomic ring ligands such as boraaryl (see, e.g., U.S. Pat. No. 5,554,775), pyrrolyl, indolyl, (U.S. Pat. No. 5,539,124), or azaborolinyl groups (U.S. Pat. No. 5,902,866). Substituted metallocenes, constrained-geometry catalysts, bridged complexes, and many heterometallocenes offer interesting advantages, including higher activity, control over polyolefin properties, and stereoregular polymers. Variety, however, comes at a price: ligands used to make many of these catalysts require costly multi-step syntheses from expensive and often hard-to-handle starting materials and reagents. In sum, there is a continuing need for single-site catalysts that can be prepared inexpensively and in short order. In particular, there is a need for catalysts that can be tailored to have good activities and to give polyolefins with desirable physical properties. SUMMARY OF THE INVENTION The invention is a single-site olefin polymerization catalyst. The catalyst comprises an activator and an organometallic complex. The organometallic complex comprises a Group 3 to 10 transition or lanthanide metal, M, and at least one indenoindolyl ligand that is π-bonded to M. The invention includes a three-step method for making the organometallic complex. First, an indanone reacts with an aryl hydrazine in the presence of a basic or acidic catalyst to produce an aryl hydrazone. Next, the aryl hydrazone is cyclized in the presence of an acidic catalyst to produce an indenoindole ligand precursor. Finally, the precursor is deprotonated, and the resulting anion reacts with a Group 3 to 10 transition or lanthanide metal source to produce the desired organometallic complex. The invention provides a remarkably simple synthetic route to single-site olefin polymerization catalysts. Because many indanones and aryl hydrazines are commercially available or easily made, a wide variety of organometallic complexes that contain n-bonded indenoindolyl ligands can be expeditiously prepared. The ease and inherent flexibility of the synthesis puts polyolefin makers in charge of a new family of single-site catalysts. DETAILED DESCRIPTION OF THE INVENTION Catalysts of the invention comprise an activator and an organometallic complex. The catalysts are “single site” in nature, i.e., they are distinct chemical species rather than mixtures of different species. They typically give polyolefins with characteristically narrow molecular weight distributions (Mw/Mn<3) and good, uniform comonomer incorporation. The organometallic complex includes a Group 3 to 10 transition or lanthanide metal, M. More preferred complexes include a Group 4 to 6 transition metal; most preferably, the complex contains a Group 4 metal such as titanium or zirconium. The organometallic complex also comprises at least one indenoindolyl ligand that is π-bonded to M. By “indenoindole,” we mean an organic compound that has both indole and indene rings. The five-membered rings from each are fused, i.e., they share two or more carbon atoms. Preferably, the rings are fused such that the indole nitrogen and the only sp 3 -hybridized carbon on the indenyl ring are “trans” to each other. Such is the case in an indeno[3,2-b]indole ring system such as: To identify how the rings are fused, the indene ring is numbered beginning with the —CH 2 — group. The “b” side of the indole ring matches the “3,2” side of the indene. In accord with IUPAC Rule A-21.5, the order of the numbers (3,2) conforms to the direction of the base (indolyl) component (i.e., from a to b). Suitable ring systems include those in which the indole nitrogen and the sp 3 -hybridized carbon of the indene are beta to each other, i.e., they are on the same side of the molecule. This is an indeno[2,3-b]indole ring system: Any of the ring atoms can be unsubstituted or substituted with one or more groups such as alkyl, aryl, aralkyl, halogen, silyl, nitro, dialkylamino, diarylamino, alkoxy, aryloxy, thioether, or the like. Additional fused rings can be present, as long as an indenoindole moiety is present. For example, a benzo ring can be fused in the “e,” “f,” or “g” positions of either or both of the indene and indole rings, as in a benzo[f]indeno[3,2-b]indole system: Numbering of indenoindoles follows IUPAC Rule A-22. The molecule is oriented as shown above, and numbering is done clockwise beginning with the ring at the uppermost right of the structure. Thus, 10-methyl-5H-indeno[3,2-b]indole is numbered as follows: Suitable indenoindole ligand precursors include, for example, 5,10-dihydroindeno[3,2-b]indole, 4,8,10-trimethyl-5H-indeno[3,2-b]indole, 4-tert-butyl-8-methyl-5,10-dihydroindeno[3,2-b]indole, 4,8-dichloro-5,10-dihydroindeno[3,2-b]indole, 10-methylbenzo[f]-5H-indeno[3,2-b]indole, benzo[g]-5,10-dihydroindeno[3,2-b]indole, 5,10-dihydroindeno[3,2-b]benzo[e]indole, benzo[g]-5,10-dihydroindeno[3,2-b]benzo[e]indole, and the like. The indenoindolyl ligand is generated by deprotonating a ligand precursor with a base to give an anionic ring system with a high degree of aromaticity (highly delocalized). Reaction of the anion with, e.g., a transition metal halide gives the desired organometallic complex. The indenoindolyl ligand is π-bonded to M in the complex. The organometallic complex optionally includes one or more additional polymerization-stable, anionic ligands. Examples include substituted and unsubstituted cyclopentadienyl, fluorenyl, and indenyl, or the like, such as those described in U.S. Pat. Nos. 4,791,180 and 4,752,597, the teachings of which are incorporated herein by reference. A preferred group of polymerization-stable ligands are heteroatomic ligands such as boraaryl, pyrrolyl, indolyl, quinolinyl, pyridinyl, and azaborolinyl as described in U.S. Pat. Nos. 5,554,775, 5,539,124, 5,637,660, and 5,902,866, the teachings of which are incorporated herein by reference. The organometallic complex also usually includes one or more labile ligands such as halides, alkyls, alkaryls, aryls, dialkylaminos, or the like. Particularly preferred are halides, alkyls, and alkaryls (e.g., chloride, methyl, benzyl). The indenoindolyl and/or polymerization-stable ligands can be bridged. For instance, a —CH 2 —, —CH 2 CH 2 —, or (CH 3 ) 2 Si bridge can be used to link two indenoindolyl groups through the indolyl nitrogens. Groups that can be used to bridge the ligands include, for example, methylene, ethylene, 1,2-phenylene, and dialkyl silyls. Normally, only a single bridge is included. Bridging changes the geometry around the transition or lanthanide metal and can improve catalyst activity and other properties such as comonomer incorporation. Exemplary organometallic complexes: 10H-indeno[3,2-b]indolyl titanium trichloride, 10H-indeno[3,2-b]indolyl zirconium trichloride, bis(3,7-dimethyl-10H-indeno[3,2-b]indolyl)titanium dimethyl, (3-tert-butyl-8,10-dimethylindeno[3,2-b]indolyl)zirconium trichloride, bis(10H-indeno[3,2-b]indolyl)zirconium dichloride, (10-phenyl-benzo[g]-indeno[3,2-b]indolyl)zirconium trichloride, (cyclopentadienyl)(10H-indeno[3,2-b]indolyl)zirconium dichloride, (8-quinolinoxy)(10H-indeno[3,2-b]indolyl) titanium dichloride, (1-methylborabenzene)(10H-indeno[3,2-b]indolyl)zirconium dimethyl, ansa-methylene-N,N′-bis(10H-indeno[3,2-b]indolyl)zirconium dichloride, and the like. The catalysts include an activator. Suitable activators ionize the organometallic complex to produce an active olefin polymerization catalyst. Suitable activators are well known in the art. Examples include alumoxanes (methyl alumoxane (MAO), PMAO, ethyl alumoxane, diisobutyl alumoxane), alkylaluminum compounds (triethylaluminum, diethyl aluminum chloride, trimethylaluminum, triisobutyl aluminum), and the like. Suitable activators include acid salts that contain non-nucleophilic anions. These compounds generally consist of bulky ligands attached to boron or aluminum. Examples include lithium tetrakis(pentafluorophenyl)borate, lithium tetrakis(pentafluorophenyl)aluminate, anilinium tetrakis(pentafluorophenyl)borate, and the like. Suitable activators also include organoboranes, which include boron and one or more alkyl, aryl, or aralkyl groups. Suitable activators include substituted and unsubstituted trialkyl and triarylboranes such as tris(pentafluorophenyl)borane, triphenylborane, tri-n-octylborane, and the like. These and other suitable boron-containing activators are described in U.S. Pat. Nos. 5,153,157, 5,198,401, and 5,241,025, the teachings of which are incorporated herein by reference. The amount of activator needed relative to the amount of organometallic complex depends on many factors, including the nature of the complex and activator, the desired reaction rate, the kind of polyolefin product, the reaction conditions, and other factors. Generally, however, when the activator is an alumoxane or an alkyl aluminum compound, the amount used will be within the range of about 0.01 to about 5000 moles, preferably from about 0.1 to about 500 moles, of aluminum per mole of M. When the activator is an organoborane or an ionic borate or aluminate, the amount used will be within the range of about 0.01 to about 5000 moles, preferably from about 0.1 to about 500 moles, of activator per mole of M. If desired, a catalyst support such as silica or alumina can be used. However, the use of a support is generally not necessary for practicing the process of the invention. The invention includes a three-step method for making the organometallic complex. In a first step, an indanone reacts with an aryl hydrazine in the presence of a basic or acidic catalyst to produce an aryl hydrazone by a known synthetic procedure. Indanones are bicyclic compounds that have a cyclopentanone ring fused to a benzene ring. Both rings can be unsubstituted or substituted with alkyl, aryl, aralkyl, nitro, halide, thioether, or other groups. Additional fused rings can be present as long as an indanone moiety is present. Suitable indanones include, for example, 1-indanone, 2-indanone, 6-methylindan-1-one, 5-chloroindan-1-one, 6-nitroindan-2-one, benzol[f]indan-1-one, and the like, and mixtures thereof. Aryl hydrazines are aromatic compounds that have a hydrazine (—NHNH 2 ) group attached to an aromatic ring. They are often used and commercially available in the form of the acid salt, as in phenyl hydrazine hydrochloride. The aromatic ring of the aryl hydrazine can be substituted with the groups described above, and it can be fused to other rings. Suitable aryl hydrazines include, for example, phenyl hydrazine, p-tolyl hydrazine, m-tolyl hydrazine, p-chlorophenyl hydrazine, 1-naphthyl hydrazine, 2-naphthyl hydrazine, and the like, and mixtures thereof. The ability to vary the substituents on the indanone and aryl hydrazine provides catalyst makers access to a diverse array of indenoindolyl ligands. This allows them to “fine tune” the activity of the corresponding organometallic complexes and, ultimately, the physical properties of the polyolefins. Because of the unique geometries of their active sites, some of the complexes should be valuable for making stereoregular polyolefins such as isotactic or syndiotactic polypropylene. A wide variety of well-known acidic and basic compounds catalyze the reaction between the aryl hydrazine and the indanone. Examples include hydrochloric acid, acetic acid, sulfuric acid, p-toluenesulfonic acid, ammonia, triethylamine, sodium hydroxide, potassium hydroxide, sodium methoxide, sodium acetate, and the like. Usually, the aryl hydrazine and the indanone are simply heated together with the catalyst, often with a reaction solvent, for a time needed to give the aryl hydrazone. The reaction product can be isolated and purified by conventional means (e.g., filtration, recrystallization), but more often, the aryl hydrazone is used in the next step without purification. A typical procedure is shown in J. Chem. Soc . (1952) 2225. In step two, the aryl hydrazone cyclizes in the presence of an acidic catalyst in a Fischer indole reaction with elimination of ammonia to give an indenoindole ligand precursor. The reaction apparently involves an interesting [3,3]sigmatropic rearrangement (see J. March, Advanced Organic Chemistry , 2 nd ed. (1977) 1054). A variety of acidic catalysts are suitable, including, for example, Lewis acids (zinc chloride, boron trifluoride), and protic acids (hydrochloric acid, acetic acid, p-toluenesulfonic acid). Usually, the crude aryl hydrazone is simply heated with the acidic catalyst for a brief period to cause the cyclization reaction. The reaction product is isolated and purified by any suitable method. In one method, the cyclization reaction mixture is poured into ice water and extracted into an organic solvent. The solution is dried, filtered, and evaporated to give the crude indenoindole ligand precursor, which can be further purified by recrystallization. In contrast to the previous step, it is preferred to purify this reaction product prior to using it in the next step. In step three of the method, the ligand precursor is deprotonated by reacting it with at least one equivalent of a potent base such as lithium diisopropylamide, n-butyllithium, sodium hydride, a Grignard reagent, or the like. The resulting anion is reacted with a Group 3 to 10 transition or lanthanide metal source to produce an organometallic complex. The complex comprises the metal, M, and at least one indenoindolyl ligand that is π-bonded to the metal. Any convenient source of the Group 3 to 10 transition or lanthanide metal can be used. Usually, the source is a complex that contains one or more labile ligands that are easily displaced by the indenoindolyl anion. Examples are halides (e.g., TiCl 4 , ZrCl 4 ), alkoxides, amides, and the like. The metal source can incorporate one or more of the polymerization-stable anionic ligands described earlier. The organometallic complex can be used “as is.” Often, however, the complex is converted to an alkyl derivative by treating it with an alkylating agent such as methyl lithium. The alkylated complexes are more suitable for use with certain activators (e.g., ionic borates). Step three is normally performed by first generating the indenoindolyl anion at low temperature (0° C. to −100° C.), preferably in an inert solvent (e.g., a hydrocarbon). The anion is then usually added to a solution of the transition or lanthanide metal source at low to room temperature. After the reaction is complete, by-products and solvents are removed to give the desired transition metal complex. Examples A and B below illustrate typical catalyst syntheses. The catalysts are particularly valuable for polymerizing olefins. Preferred olefins are ethylene and C 3 -C 20 α-olefins such as propylene, 1-butene, 1-hexene, 1-octene, and the like. Mixtures of olefins can be used. Ethylene and mixtures of ethylene with C 3 -C 10 α-olefins are especially preferred. Many types of olefin polymerization processes can be used. Preferably, the process is practiced in the liquid phase, which can include slurry, solution, suspension, or bulk processes, or a combination of these. High-pressure fluid phase or gas phase techniques can also be used. The process of the invention is particularly valuable for solution and slurry processes. The olefin polymerizations can be performed over a wide temperature range, such as about −30° C. to about 280° C. A more preferred range is from about 30° C. to about 180° C.; most preferred is the range from about 60° C. to about 100° C. Olefin partial pressures normally range from about 15 psia to about 50,000 psia. More preferred is the range from about 15 psia to about 1000 psia. Catalyst concentrations used for the olefin polymerization depend on many factors. Preferably, however, the concentration ranges from about 0.01 micromoles per liter to about 100 micromoles per liter. Polymerization times depend on the type of process, the catalyst concentration, and other factors. Generally, polymerizations are complete within several seconds to several hours. Examples 1-9 below illustrate typical olefin polymerizations using catalysts of the invention. As the examples show, the catalysts have good activity and give polymers with favorable melt-flow properties. The following examples merely illustrate the invention. Those skilled in the art will recognize many variations that are within the spirit of the invention and scope of the claims. Ligand Precursor Preparation 3,10-Dimethyl-5H-indeno[3,2-b]indole, the ligand precursor for the catalysts prepared in Examples A and B, is prepared by the method of Buu-Hoi and Xuong ( J. Chem. Soc . (1952) 2225) by reacting p-tolylhydrazine with 1-indanone in the presence of sodium acetate/ethanol, followed by reaction of the secondary amine product with Mel in the presence of a basic catalyst (NaOH or Na 2 CO 3 ) to give the desired N-methylated product: EXAMPLE A Preparation of Catalyst A 3,1 0-Dimethyl-5H-indeno[3,2-b]indole is deprotonated with n-butyllithium in toluene. A solution of the resulting anion (1.18 g, 0.0049 mol) in tetrahydrofuran (20 mL) is added to a solution of zirconium tetrachloride (0.60 g, 0.0026 mol) in THF (40 mL) at −78° C. After stirring for 15 h at room temperature, a bright red precipitate is isolated and and vacuum dried. The resulting material (0.71 g) is used without further purification. The principal catalyst component is bis(3,10-dimethylindeno[3,2-b]indolyl)zirconium dichloride: EXAMPLE B Preparation of Catalyst B 3,10-Dimethyl-5H-indeno[3,2-b]indole is deprotonated with n-butyllithium in diethyl ether. The resulting anionic complex (2.2 g, 0.0703 mol) is dissolved in diethyl ether (50 mL). Zirconium tetrachloride (0.819 g, 0.00352 mol) is added to the anion at −78° C. The reaction mixture is stirred for 15 h at room temperature, and solvent is removed under vacuum to obtain a red catalyst sample that is used without further purification. The principal catalyst component is bis(3,10-dimethylindeno[3,2-b]indolyl)zirconium dichloride. EXAMPLES 1-9 Ethylene Polymerization—General Procedure Slurry polymerizations are performed in a 1.7-L, stainless-steel stirred reactor. Dry, oxygen-free toluene (850 mL) is charged to the clean, dry, oxygen-free reactor at room temperature. The activator used in each polymerization is a solution of 10 wt. % methalumoxane (MAO) in toluene (from Ethyl Corporation). The specified amounts (from Table 1 below) of MAO, 1-butene (comonomer), and hydrogen are then added, in that order, to the reactor. The reactor is heated to the desired reaction temperature and allowed to equilibrate. Ethylene is introduced to give a total pressure in the reactor of 150 psig, and the reactor is again allowed to equilibrate. The desired quantity of catalyst, dissolved in toluene, is then injected into the reactor to start the polymerization. Ethylene is fed on demand to keep the reactor pressure at 150 psig. At the end of 1 h, the ethylene flow is stopped, and the reaction mixture cools to room temperature. The polymer is isolated by vacuum filtration, is dried overnight in a vacuum oven, and is weighed and characterized. Table 1 gives polymerization conditions; Table 2 gives polymer properties. Example 3 uses a slightly modified procedure: Half of the MAO is added as described above, while the other half is mixed with the organometallic complex and allowed to react for 15 min. prior to injecting the catalyst mixture into the reactor. The melt index of the polymer is measured using ASTM D-1238, Conditions E and F. MI2 is the melt index measured with a 2.16 kg weight (Condition E). MI20 is the melt index measured with a 21.6 kg weight (Condition F). MFR is the ratio of MI20 to MI2. Densities are measured in using ASTM D-1505. Table 1 summarizes process conditions and Table 2 gives polymer properties for the examples. The preceding examples are meant only as illustrations. The following claims define the invention. TABLE 1 Polymerization Conditions Catalyst Amt. MAO Temp. 1-butene Hydrogen Ex. # ID (mmoles) (mmoles) (° C.) (mL) (mmoles) 1 A 8.0 × 10 −4 9.0 80 0 0 2 A 3.2 × 10 −3 9.0 80 0 0 3 A 3.2 × 10 −3 9.0 80 0 0 4 A 3.2 × 10 −3 9.0 110 0 0 5 A 8.0 × 10 −3 9.0 80 0 0 6 A 8.0 × 10 −3 9.0 110 0 60 7 A 8.0 × 10 −3 9.0 110 20 60 8 A 3.2 × 10 −3 6.0 80 0 0 9 B 8.0 × 10 −3 9.0 80 0 0 Catalyst A, B = bis(3,10-dimethylindeno[3,2-b]indolyl)zirconium dichloride; MAO = methalumoxane TABLE 2 Polymerization Results Catalyst Polymer Productivity Ml 2 Ml 20 Density Ex. # ID wt. (g) (kg/g Zr) (dg/min) (dg/min) (g/mL) 1 A 4.8 65.8 — — — 2 A 29.0 99.4 0.048 1.41 0.963 3 A 21.6 74.0 0.028 0.63 — 4 A 9.4 32.3 1.32 7.98 — 5 A 49.9 68.4 0.62 16.6 0.967 6 A 36.6 50.2 1092 — >0.970 7 A 33.5 45.9 2075 — 0.973 8 A 19.0 65.1 0.023 0.30 — 9 B 31.8 43.6 0.034 1.27 — Catalyst A, B = bis(3,10-dimethylindeno[3,2-b]indolyl)zirconium dichloride; MAO = methalumoxane

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BACKGROUND OF THE INVENTION 1. Field of the Invention Solar heating, particularly methods for collecting solar energy for heating an office building during the winter and cooling during the summer. Buildings have been designed to maximize shielding of vision areas from the sun's rays, while utilizing a series of collecting panels, exposed to the sun's rays to transfer solar energy to heating and cooling systems. 2. Description of the Prior Art The prior art includes U.S. Pat. Nos.: BREMSER 2,030,350 NEWTON 2,396,338 NEWTON 2,342,211 GAY 2,584,573 LOF 2,680,565 BENEDEK 2,933,885 HAY 3,450,192 HAY 3,563,305 The Newton U.S. Pat. Nos. 2,342,211 and 2,396,338 disclose systems utilizing a radiation unit to transfer heat for desired heating and cooling purposes. Independent heat and cold storing means are heated and cooled by a single radiation device. Gay suggests storing heat in the earth or ground beneath a building for subsequent usage. Lof provides a solar heat trap containing a plurality of zones or passages within which a fluid is circulated to adsorb heat for subsequent transfer, and means are provided for limiting heat radiation within the confined zones and for storing excess heat released through the zones. Bremser discloses a solar operated refrigerating system illustrating a conventional absorption cycle type of cooling system, which itself is a per se known manner of effecting refrigeration from solar energy. Such a conventional absorption cycle may also be advantageously used within the teachings of the instant invention, along with any other known refrigeration cycle of the prior art. The Hay patents show a system wherein exterior insulation is moved over different liquid areas for the purpose of storing or rejecting solar energy. The Benedek patent discloses a heat storage accumulator system and equipment for operating the same. SUMMARY OF THE INVENTION Heat loss through the exterior walls is minimized by using maximum insulation in the opaque area and double glazing vision areas. Radiant energy is collected by means of a series of heat collectors prominently displayed on the east, west and southern facades of the building. Chilling loss during the summer months is minimized by orienting the vision glasses on the north side facade, northeasterly on the east facade and northwesterly on the west facade. On the south facade the vision glasses may be shaded by superposed heat collecting panels. A heat responsive fluid is circulated in radiant contact with the heat collector panels and thence to the desired heating and cooling systems. The circulating fluid is blocked sequentially in those areas where the adjacent panels are not exposed to the sun. The heat may be used to operate a low temperature absorption or other conventional type of refrigeration system, as well as a building heater. Forced air may also be preheated by means of the heated circulating fluid which may be stored wihin the building basement. As a consequence, the system is a net exporter of heat throughout the year. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of a proposed building, showing the southern and western facades with shading collecting panels exposed to the sun; FIG. 2 is a perspective of the north and west facades, showing the vision glass oriented respectively north and northwesterly, the north facade being without heat collecting panels; FIG. 3 is a fragmentary enlarged view of the west facade, showing angular orientation of the heating panels and north-northwesterly orientation of the double glazed vision areas; FIG. 4 is an enlarged rear elevation, showing the south facade and adjacent west facade with opaque solar energy collecting panels used complementally as shading for the vision areas; FIG. 5 is a top plan showing the northwesterly and northeasterly orientation of the west and east vision areas; FIG. 6 is a fragmentary section taken along section line 6--6 of the south facade and showing the opaque roof-top heat collector, as well as lower collectors superposed at a 45° angle as a shield or shade for the vision areas; FIG. 7 is a fragmentary vertical section, taken along section line 7--7 of FIG. 5 and showing angular orientation of the heat collecting panels on the east facade, as well as the northeasterly orientation of the vision glass; FIG. 8 is an enlarged transverse section taken along section line 8--8 of FIG. 7 and showing the positioning of the double vision glass, the collector plate and circulating liquid channels, as well as back-up insulation. FIG. 9 is a schematic view of suggested building air and piping system; FIG. 10 is a schematic view of suggested building condensor water system; and FIG. 11 is a schematic view of a suggested building heat recovery and storage system. DESCRIPTION OF PREFERRED EMBODIMENTS In FIG. 1 a multi-story office building generally designated as 20 is illustrated as having inclined southern rooftop opaque collecting area 26, southern facade 25 and western facade 24. In FIG. 2 the building northern facade 28 is illustrated as having conventional double pane vision areas 34 and opaque insulated panels 32. In FIG. 4 the southern facade is further illustrated as having double pane horizontal vision areas 46 shaded by angularly superposed disposed opaque collector panels 44. FIG. 5 the building layout is generally illustrated. West facade 24 has its vision areas 38, north-northwesterly disposed with adjacent opaque collector panels 36 exposed to the prevailing sun. Similarly in the eastern facade 30 the vision areas 40 are north-northeasterly oriented intermediate opaque, angularly disposed or staggered collector panels 42. In the south facade vision areas 46 are shaded by horizontally disposed opaque collector panels 44. Manifestly, the angle of the windows on east and west facades, as well as the angle of the collector panels may be varied, according to the sun'latitude. Similarly, the angle of the shading collector panels 44 may be varied so as to prevent the winter sun exposure to the vision area. FIG. 6 the rooftop collector panel 22 is illustrated fragmentarily and superposed with respect to collector panels 44 which shade the respective vision areas 46. The rooftop and east-west collector panels may be constructed similarly to include a clear and insulated clear glass cover 51, a collector plate 52, with integral liquid channels 53 and a back-up insulation member 60. Insulation 48 may be interposed intermediate the bottom of the collector panel and the building wall, so as to enclose a circulating plenum or duct 50. In FIG. 8 the east-west facade collector panel is illustrated in enlarged detail. The collector plate may have a selective surface coating and may be a flat metal plate clad with formed metal plate. Alternatively, the collector panel may include a flat metal plate with welded attached tubes or other combination. In FIG. 7 the collector panels on the east facade are disposed at a 30° angle; however, this angle may be varied, according to latitude. The individual panels may have disconnect zones I, II, III or the like which may be circuited to cut out of the system when shaded from the sun. In FIG. 9 the air and piping diagram is illustrated, as including individual air supply boxes 61 and 63, respectively representing a variable volume interior room air supplies as well as exterior room air supplies that are also illustrated for heat exchange as interposed between the low rise supply air conduit 58 and the reheat water supply 62 conduit and return 64. As illustrated in FIG. 9 air in the low rise supply conduit 58, for example, is directed into interior supply 61 and also into the exterior room supply 63 with reheat exchange to reheat water from reheat coil pump 91. This air is schematically illustrated to return to the low rise air supply 72 through air return 59. As shown, the reheat water from 63 is returned through 64 upwardly past all such reheat boxes 63 and finally returned by reheat water reverse line 71 to hot water storage tank 86. A high rise air supply unit 70 and a low rise air supply unit 72 may be employed adjacent the reheat water reverse return conduit 71. As illustrated in FIGS. 9 and 10, chilled water cooling coils 74 and 78 may be positioned above chilled water supply and return conduit 76 communicating respectively with the storage tank 86 and chilled water pumps 84 chillers 82 and hot water pumps 80. Reheat coil pumps 91 may be positioned, so as to have access to storage tank 86 and the reheat water supply and return conduit 62, 64. Manifestly, a series of valves may be employed to block off circulation in vertical segments, of those panels on the southern facade, as well as lateral and vertical segments of those panels on the eastern and western facades. These valves to selectively control heat recovery by admitting the solar heated water supply, for example to certain liquid channels 53 in zones I, II, and III of FIG. 7 are schematically illustrated as VI, VII and VIII. In FIG. 10 a condensor water diagram is further illustrated as comprising chillers 82, condenser water supply 94 and condensor water reverse return 92 communicant with condensor water pumps and an optional cooling tower 97 with associated condenser water pumps 99 positioned in the building roof. Typical lighting fixtures 98 are illustrated as cooled by conduit 96 leading from the condensor water supply. As illustrated in FIGS. 9 and 10 taken together, the representation of "chiller" 82 is firstly schematic of a heat pump system wherein hot water pumps 80 supply an energy source to effect chilling of the chilled water return from 76. As hereinabove disclosed, any other type of thermodynamic heat removal may be used to supply chilled fluid to interior cooling coils 78. The cooling circuit from 84 together with the heated liquid at 80 also schematically illustrate interconnections such as are conventional in solar operated absorption refrigeration systems. In this respect the U.S. Pat. to Bremser, No. 2,030,350, herinabove incorporated, represents a conventional solar operated absorption circuit which may be the operative fluid circuit 76 between a heat source at 80 and the cooling or evaporator coil at 78. In FIG. 11 a heat recoverage and storage system is illustrated as including storage tank 86 having median baffle 88, heat recovery pumps 110 and auxilliary stand by heater 108, communicating with solar heating water return 106. The heat recovery pumps communicate with solar heating water supply 100, as well as solar heating water reverse return 102. An expansion tank 104 may be positioned at the building rooftop. In a typical 35 story office building, a controlled interior climate may be achieved by the following: 1. Minimization of heating and air conditioning requirements by respectively minimizing heat loss in winter through the exterior wall by means of maximum insulation in opaque areas, double glazing in vision areas, and by minimizing solar heat gain in the summer by orienting vision glass to the north on the north facade, north-northwest on the west side, and completely shading vision glass on the south side by means of angled solar collectors and; 2. Collection of all solar energy striking the building facade and roof by means of double or triple glazed clear glass covered collectors made of coated copper or aluminum plates, with integral or attached fluid carrying channels, connected to pipes, containing a liquid (e.g., water or water and ethylene glycol) which is heated to optimum temperature, returned to a central location at the base of the building, then redistributed through the building where needed for heating in the winter, and used to operate an absorption cycle or other such known system operable upon heat exchange with a heated fluid, amply illustrated by the prior art for a refrigeration equipment in the summer. An insulated storage tank in the basement stores excess hot liquid for night time cooling or heating, any excess hot liquid can be sold to neighboring buildings; 3. The integration of the above two principles results in a novel design which, with the exception of energy for lighting, can be a net exporter of energy, meaning that the excess of solar energy collected on sunny and mildly overcast days vs. that needed for heating and cooling the subject building can be exported in a quantity greater than that needed to be imported (gas, oil, steam or electric backup) on a day or days when solar energy is not available in adequate quantities to heat or cool subject building. As shown in FIGS. 9 and 10, the particular chillers 82 and 90, respectively, for air conditioning or cooling purposes may be a conventional low temperature (200° to 245°F) "water fired" unit such as that manufactured by Arkla-Servel and designated WF-1200.

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CROSS-REFERENCE TO RELATED APPLICATIONS This application is a continuation of application Ser. No. 09/482,189, filed Jan. 12, 2000, now U.S. Pat. No. 6,562,438, issued May 13, 2003, which is a divisional of application Ser. No. 09/041,829, filed Mar. 12, 1998, now U.S. Pat. No. 6,051,149, issued GOVERNMENT LICENSE RIGHTS This invention was made with government support under Contract No. DABT 63-97-C-0001 awarded by Advanced Research Projects Agency (ARPA). The Government has certain rights in this invention. BACKGROUND OF THE INVENTION Field of the Invention: This invention relates to methods for forming each masks on substrates which are too large to efficiently employ photolithography techniques. Such etch masks may be used to form such structures as micropoint cathode emitters for field emission flat panel video displays, spacers for liquid crystal displays, quantum dots, or other features which may be randomly distributed on a surface. State of the Art: For considerably more than half a century, the cathode ray tube (CRT) has been the principal device for electronically displaying visual information. Although CRTs have been endowed during that period with remarkable display characteristics in the areas of color, brightness, contrast and resolution, they have remained relatively bulky and power hungry. The advent of portable computers has created intense demand for displays which are lightweight, compact, and power efficient. Although liquid crystal displays (LCDs) are now used almost universally for laptop computers, contrast is poor in comparison to CRTs, only a limited range of viewing angles is possible, and battery life is still measured in hours rather than days. Power consumption for computers having a color LCD is even greater, and thus, operational times are shorter still, unless a heavier battery pack is incorporated into those machines. In addition, color screens tend to be far more costly than CRTs of equal screen size. As a result of the drawbacks of liquid crystal display technology, field emission display technology has been receiving increasing attention by the industry. Flat panel displays utilizing such technology employ a matrix-addressable array of cold, pointed, field emission cathodes in combination with a luminescent phosphor screen. Somewhat analogous to a cathode ray tube, individual field emission structures are sometimes referred to as vacuum microelectronic triodes. Each triode has the following elements: a cathode (emitter tip), a grid (also referred to as the gate), and an anode (typically, the phosphor-coated element to which emitted electrons are directed). The cathode and grid elements are generally located on a baseplate, while the anode elements are located on a transparent screen, or faceplate. The baseplate and faceplate are spaced apart from one another. As the space between the baseplate and faceplate must be evacuated, a hermetic seal joins the peripheral edges of the baseplate to those of the faceplate. Although the phenomenon of field emission was discovered in the 1950's, it has been within only the last ten years that extensive research and development have been directed at commercializing the technology. As of this date, low-power, high-resolution, high-contrast, monochrome flat panel displays with a diagonal measurement of about 15 centimeters have been manufactured using field emission cathode array technology. Although useful for such applications as viewfinder displays in video cameras, their small size makes them unsuited for use as computer display screens. Several engineering obstacles must be overcome before large screen field emission video displays become commercially viable. One such problem relates to the, formation of load-bearing spacers which are required to maintain physical separation of the baseplate and the phosphor coated faceplate in the presence of external atmospheric pressure. Another problem relates to masking the baseplate in order to form the emitter tips. When the baseplate is no larger than the semiconductor wafers typically used for integrated circuit manufacture, the process disclosed in U.S. Pat. No. 5,391,259 to David Cathey, et al. works splendidly, as the mask particles can be formed from photoresist resin using a conventional photolithography process. However, when the baseplate is larger than those semiconductor wafers, conventional photolithographic techniques utilized in the integrated circuit manufacturing industry are much more difficult to apply. This disclosure is directed toward the problem of forming emitter tips on a large area baseplate. Erie Knappenberger of Micron Display Technology, Inc. has proposed a new method for forming a mask pattern on a field emission display baseplate using beads or particles as the masking medium. As etch masks for a random pattern of similarly sized dots formed by dispensing glass or plastic beads suspended in a solution on an etchable surface are known to suffer from the problem of aggregation (i.e., multiple beads aggregating together on the surface), a nebulizer or atomizer is used to generate an aerosol containing particles. A monodispersed aerosol may be produced by utilizing a nebulizer or atomizer which produces droplets which are less than twice the size of the beads or particles within the mixture that is to be atomized. Alternatively, the mixture may be diluted so that the probability of two particles or beads being included within a single droplet is small. The aerosol thus created is then applied to a substrate, producing a uniform mono-layer of particles having substantially no aggregation. The particles may be used as a micropoint mask pattern which, when subjected to an etch step, forms field emitter tips for a field emission display or other micro-type structures. An alternative method for minimizing aggregation is to use two types of particles, one of which functions as a masking particle, the other which functions as a spacer particle. Thus, even if aggregation of particles is intentionally generated, the spacer particles may be removed by various techniques such as a chemical dissolution or evaporation, thereby minimizing aggregation of the masking particles themselves. Another masking technique taught by U.S. Pat. No. 5,676,853 to James J. Alwan, utilizes a mixture of mask particles and spacer particles. The spacer particles space the mask particles apart from one another, and the ratio of spacer particle size to mask particle size and the ratio of spacer particle quantity to mask particle quantity control the distance between mask particles and the uniformity of distribution of mask particles. An additional masking technique taught by U.S. Pat. No. 5,510,156 to Yang Zhao utilizes latex spheres which are deposited in a mono-layer on a surface, shrunk to reduce their diameters, and subsequently covered with an aluminum layer. When the reduced-diameter spheres are dissolved, apertures are formed in the aluminum layer, and the apertures are subsequently utilized to etch an underlying layer. Still another masking technique is taught by U.S. Pat. No. 5,399,238 to Nalin Kumar. This technique relies on physical vapor deposition to place randomly distributed metal nuclei on a surface. The nuclei form a discontinuous etch mask on the surface of a layer to be etched. Even under the best of circumstances, the use of the foregoing masking techniques will produce totally random patterns. A more regular mosaic pattern may be produced by the process disclosed in U.S. Pat. No. 4,407,695 to Harry W. Deckmian. Using this process, a mono-layer film of spherical colloidal particles is deposited on a surface to be etched. A spinning step which applies centripetal force to the particles is employed to improve packing density. The packed mono-layer is then ion etched to produce tapered columnar features. The tapering of the features results from continuing degradation of the colloidal particles during the ion etch step. A masking technique similar to that patented by Deckrnan is disclosed in U.S. Pat. Nos. 5,220,725; 5,245,248 and 5,660,570 to Chung Chan, et al. This technique is disclosed in the context of fabricating an interconnection device having atomically sharp projections which can function as field emitters at voltages compatible with conventional integrated circuit structures. The projections are formed by creating a mono-layer of latex microspheres on a surface to be etched by spraying or pouring a colloidal suspension of the microspheres on the surface and, then, subjecting the mono-layer covered surface to either a wet etch or a reactive-ion etch. What is needed is a simplified process for forming more regular mask patterns having no masking defects caused by two or more masking particles being too close to one another. The desired process should be capable of producing mask patterns which suffer little or no degradation during plasma etches. In addition, the process should be capable of forming masks which are usable for both reactive-ion etches and wet etches. BRIEF SUMMARY OF THE INVENTION The heretofore expressed needs are fulfilled by a new process for forming a mask pattern. Beads, each of which has a substantially unetchable core covered by a removable spacer coating are used to form a discontinuous, regular hexagonal mask pattern. Each of the beads is preferably both spherical and of a particular size, as is each of the cores. For a preferred embodiment of the process, a reactive-ion-etchable material layer (hereinafter “the target layer”) is coated with a thin thermo-adhesive layer. A bead confinement wall, or frame, is then secured to the peripheral edges of the target layer using one of several available techniques. For example, the confinement wall may be bonded to the thermo-adhesive layer, or it may be secured to the target layer with spring clips. In the former case, the confinement wall may be heated so that when it is placed on the thermo-adhesive layer, it bonds thereto. Beads are then dispensed onto the thermo-adhesive layer, in a quantity at least sufficient to form a hexagonally packed mono-layer on the adhesive layer with the boundaries of the confinement wall. The bead-covered substrate is then subjected to vibration of a frequency and amplitude that will cause a settling of the beads to their lowest energy level, a state where optimum packing is achieved with a hexagonal mono-layer bead pattern in contact with the thermo-adhesive layer. Optimum hexagonal packing having been achieved, the resultant assembly is heated, causing the layer of beads directly in contact with the adhesive layer to adhere thereto. The beads which are not in contact with the adhesive layer do not adhere to it. The unadhered beads are then discarded. This is accomplished, most easily, by inverting the assembly. They may also be removed by washing them from the assembly, after which the assembly is dried. Spacer shell material is then removed from each of the beads, leaving only the cores visible in a top plan view. At least two methods may be employed to remove the spacer shell material between the non-etchable bead cores. The bead-coated substrate may be subjected to a first reactive-ion etch which etches away all of the spacer material except that which is beneath the cores and which is in bonded contact with the adhesive layer overlaying the substrate. The first reactive-ion etch chemistry is preferably selected such that it selectively etches the spacer material, but does not significantly etch either the cores or the target layer. If the target layer is etched simultaneously with the spacer material, uneven etching of the target layer will occur, as the areas of the target layer between the beads will etch first. The regions of the target layer closest to the cores will be the last areas exposed to reactive ion bombardment. Alternatively, the spacer material on the beads may be sublimable at elevated temperatures. Thus, as the coating on the beads sublimates, each non-etchable bead core will settle until it is eventually in direct contact with the adhesive layer. The core-masked target layer is then subjected to a second reactive-ion etch, which etches the target layer and forms a column beneath each core. If the target layer is lamninar and is etched clear through to an underlying layer, a circular island of target layer material remains beneath each core. The cores are then removed, as well as any remaining spacer material beneath them. In the case where a laminar target layer is etched clear through to an underlying layer, the circular islands of target layer material that remain may be used as a secondary mask pattern during a wet isotropic etch of the underlying layer. Such a combination of a unidirectional reactive-ion etch using the bead cores as a primary mask and an omnidirectional wet etch using the islands formed by the plasma etch as a secondary mask may be used to form, micropoint cathode emitter tips in an underlying conductive or semiconductive layer. BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS The following illustrative figures are not drawn to scale, and are meant to be merely representative of the disclosed process: FIG. 1 is a cross-sectional view of a spherical bead having a spherical core covered with a spacer shell; FIG. 2 is a cross-sectional side view of an in-process baseplate assembly, which includes a silicate glass plate, on which has been deposited a conductive layer, a silicon layer, a masking layer, and a thermo-adhesive layer; FIG. 3A is a cross-sectional view of the in-process baseplate assembly of FIG. 2 following the affixing of a confinement wall to the periphery thereof; FIG. 3B is a cross-sectional side view of an alternative structure for affixing the confinement wall to the substrate structure of FIG. 2 using spring clips; FIG. 4 is a cross-sectional side view of the in-process baseplate assembly structure of FIG. 3A following the dispensing of beads within the boundaries of the confinement wall; FIG. 5 is a cross-sectional side view of the in-process baseplate assembly of FIG. 4 during a vibrational step which promotes a continuous, even hexagonal packing pattern of a mono-layer of beads on the surface of the thermo-adhesive layer; FIG. 6 is a top plan view of an ideal arrangement of hexagonally packed beads; FIG. 7 is a cross-sectional side view of the in-process baseplate assembly of FIG. 5 following an elevated temperature step which causes the lower layer of beads to adhere to the thermo-adhesive layer, FIG. 8 is a cross-sectional side view of the in-process baseplate assembly of FIG. 7 following the discarding of unadhered beads; FIG. 9 is a cross-sectional side view of the in-process baseplate assembly of FIG. 8 following removal of the confinement wall; FIG. 10 is a cross-sectional side view of the in-process baseplate assembly of FIG. 9 following a first plasma etch step which removes all spacer material from the beads except that which is immediately beneath each core; FIG. 11 is a cross-sectional side view of the in-process baseplate assembly of FIG. 10 following a second plasma etch step which anisotropically etches the masking layer to form a plurality of masking islands therefrom; FIG. 12 is a cross-sectional side view of the in-process baseplate assembly of FIG. 11 following the removal of the cores, the spacer material which underlies each core, and remaining portions of the thermo-adhesive layer; FIG. 13 is a cross-sectional side view of the in-process baseplate assembly of FIG. 12 following a first isotropic etch which forms dull micropoint cathode emitter tips within the silicon layer; FIG. 14 is a cross-sectional side view of the in-process baseplate assembly of FIG. 13 following removal of the masking islands; and FIG. 15 is a cross-sectional side view of the in-process baseplate assembly of FIG. 14 following a second isotropic etch which sharpens the existing dull micropoint cathode emitter tips. DETAILED DESCRIPTION OF THE INVENTION Although the masking process of the present invention may be utilized for nearly any masking application where an ordered array of circular features is desired, it is especially useful for the masking of substrates or coated substrates which are so expansive that conventional photolithography exposure equipment will not easily accommodate them. As a concrete example of the utility of the invention, it will be disclosed in the context of a process for fabricating an array of emitter tips for the microcathodes of a baseplate assembly for a field emission display. As a matter of clarification, a brief description of etch technology is in order. An etch that is isotropic is omnidirectional. That is, it etches in all directions at substantially the same rate. As a general rule, solution etches (usually called “wet etches”) are isotropic. For example, hydrofluoric acid solutions are commonly used to isotropically etch silicon. Although the term anisotropic literally means not isotropic, in the integrated circuit manufacturing industry, it has come to connote substantial unidirectionality. Thus, an etch that is anisotropic etches in substantially a single direction (e.g., straight down). Plasma etches typically have both isotropic and anisotropic components. Plasma etches are normally performed within an etch chamber. A conventional etch chamber generally has an upper electrode and a lower electrode to which the target is affixed. During a plasma etch, ions accelerated by an electric field applied between the two electrodes impact the target. Upon impact, the ions react with atoms on the target surface to form gaseous reaction products which are removed from the etch chamber. It is this acceleration of reactive ions within the electric field that imparts substantial unidirectionality to a plasma etch. The anisotropic component of a plasma etch can be optimized through the careful selection of equipment, etch chemistries, power settings and positioning of the article to be etched within the etch chamber. In the context of this disclosure, the term isotropic means omnidirectional; the term anisotropic means downwardly unidirectional. The emitter tips will be formed from a silicon layer by, first, creating an array of masking islands on the surface of the silicon layer and, then, performing an isotropic etch to form an emitter tip beneath each masking island. Although the materials utilized in the various layers of the representative process are presently considered to be the preferred materials for the desired application, the inventor wishes to emphasize that the process may be used for the same application, or for other applications, using a different combination of etchable and nonetchable materials. Referring now to FIG. 1, a spherical bead 100 is depicted in a cross-sectional view. The bead has a spherical core 101 covered with a spacer shell 102 . The materials from which the core 101 and the shell 102 are formed are selected such that during a particular anisotropic plasma etch, the material comprising the shell 102 may be etched selectively with respect to the material comprising the core 101 . In other words, during the plasma etch, the shell will etch, while the core will not For example, the bead cores may be formed from glass, iron or many other plasma etch-resistant materials compatible with integrated circuit processing. The shell material, on the other hand, may be formed from polymers, glasses or many other materials which are compatible with integrated circuit processing, and which may be plasma etched selectively with respect to the core material. Alternatively, the shell 102 may be formed from a material that sublimates rapidly at elevated temperatures compatible with integrated circuit manufacture (i.e., those within a range of about 200-400° C.). Paradichlorobenzene and napthalene are two such common materials. The bead cores 101 are employed as elemental masking elements, while the shells 102 set or define the spacing between the bead cores 101 . Spacing between elemental masking elements (i.e., the cores 101 ) may be adjusted by varying thickness of the shells 102 . In the drawings appended to this disclosure, beads are depicted, for the sake of clarity, as though the cores 101 are opaque elements, while the shells- 102 are depicted as though transparent. However, nothing should be inferred regarding the type of materials used from the adoption of this illustration convention. Referring now to FIG. 2, a conductive layer 202 is deposited on a silicate glass plate 201 . As conductive layer- 202 must be fairly stable during subsequent elevated temperature steps, silicides of metals such as titanium, tungsten, cobalt, nickel, platinum, and paladium may be used. A silicon layer 203 (also referred to herein as “the cathodic layer”) is deposited over the conductive layer 202 . A masking layer 204 is then deposited over the silicon layer 203 . The masking layer 204 may be a nitrided material such as silicon nitride, titanium nitride, or titanium carbonitride, a silicide of a refractory metal such as titanium, platinum or tungsten, or an unreacted metal such as aluminum, titanium, or copper. The primary consideration during the selection of the material for masking layer 204 is that it be substantially unetchable during an anisotropic plasma etch/of silicon layer 203 . Finally, a thermo-adhesive layer 205 is deposited on the upper surface of masking layer 204 . The thermo-adhesive layer 205 may be a wax or a polymer material which softens and becomes tacky when heated, and which preferably reversibly hardens when cooled. The wax may be, for example, an ester, a fatty acid, al chain long-chain alcohol, or a long-chain hydrocarbon. The polymer material may be, for example, a polyurethane resin, a polyester resin, or an epoxy resin. The silicate glass plate 201 with the additional layers deposited thereon shall now be referred to as the in-process baseplate assembly 206 . Referring now to FIG. 3A, a bead confinement wall 301 A is attached to the periphery of the thermo-adhesive layer 205 of the in-process baseplate assembly 206 . The wall 301 A may be formed from nearly any rigid or semi-rigid material such as metal, glass, or high temperature high-temperature polymeric plastic. The wall 301 A may be attached by heating it to a temperature in excess of that which will cause the thermo-adhesive layer 205 to soften and become tacky, placing it on the thermo-adhesive layer 205 , and allowing the entire in-process baseplate/wall assembly 302 to cool. Alternatively, the wall 301 A may be attached by placing it on the thermo adhesive thermo-adhesive layer 205 , heating the resulting in-process baseplate/wall assembly 302 to a temperature in excess of that which will cause the thermo-adhesive layer 205 to soften and become tacky, and allowing the entire assembly to cool. FIG. 3B depicts an alternative method of affixing the confinement wall to the in-process baseplate assembly 206 . A bead confinement wall 301 B is clipped to the in-process baseplate assembly 206 with spring clips 303 . For the sake of simplification, and because the method by which the bead confinement wall ( 301 A or 301 B) is attached to the in-process baseplate assembly 206 insignificantly affects the remainder of the process, the in-process baseplate/wall assembly of FIG. 3 B and that of FIG. 3A shall both be referred to, hereinafter, as item number 302 . Referring now to FIG. 4, a quantity of beads 100 , such as those depicted in FIG. 1, has been dispensed onto the in-process baseplate/wall assembly 302 of FIG. 3A or FIG. 3 B. The quantity of the dispensed beads 100 is at least sufficient to create a hexagonally packed mono-layer of beads 100 on the entire surface of the thermo-adhesive layer enclosed by the confinement wall 301 A or 301 B. Confinement wall 301 A or 301 B prevents the dispensed beads 100 from rolling off the edge of the in-process baseplate/wall assembly 302 . Referring now to FIG. 5, a vibration step is performed which promotes a continuous, even hexagonal packing pattern of mono-layer of beads 100 on the surface of the thermo-adhesive layer 205 . Ideally, the vibrational movement will include a vertical component that is just barely sufficient to dislodge improperly packed beads, but not those which are already properly packed in the bottom-most layer. FIG. 6 depicts an ideal arrangement of hexagonally packed beads. Referring now to FIG. 7, once a hexagonally packed mono-layer 701 that is in contact with the thermo-adhesive layer 205 has been attained, the temperature of in-process baseplate/wall/bead assembly 702 is elevated, causing each of the beads in the lower bead layer 701 to adhere to the thermo-adhesive layer 205 . Referring now to FIG. 8, once the in-process baseplate/wall/bead assembly 702 has cooled, unadhered beads (i.e., those not in lower layer 701 ) are discarded. This is accomplished, most easily, by inverting the assembly. They may also be removed by washing them from the assembly 702 , after which the assembly 702 is dried. Referring to FIGS. 8 and 9, the bead confinement wall 301 A may be removed by applying heat to the upper edge 901 thereof, allowing the applied heat to transfer through the wall 301 A until the thermo-adhesive is softened along the lower edge 902 of the wall 301 A and the wall 301 A can be released from the thermo-adhesive layer 205 . Likewise, confinement wall 301 B may be removed by releasing the spring clips 303 (see FIG. 3 B). Referring now to FIG. 10, a first anisotropic etch is used to remove all spacer material of shell 102 from the beads 100 except that circular mask island 1101 which is beneath each core 101 . The first anisotropic etch chemistry is selected such that neither the cores 101 nor the masking layer 204 is etched by the first plasma etch. Referring now to FIG. 11, a second anisotropic etch is used to etch the masking layer 204 and stop on the silicon layer 203 , forming a circular mask island 1101 beneath each core 101 . An alternative embodiment of the process combines the first and second anisotropic etches so that the spacer material of shell 102 is etched from the beads 100 during the same step that etches the masking layer 204 . In this case, the etch chemistry should be carefully selected to stop on the upper surface of silicon layer 203 . Referring now to FIG. 12, the remaining portions of the silicon layer 203 , the cores 101 and spacer material of shell 102 beneath each core 101 have been removed by washing the entire in-process baseplate assembly 206 in a solvent in which the thermo-adhesive layer 205 dissolves. For wax-based thermo-adhesives, an appropriate solvent selected from the ether, alkane, alcohol and haloalkane groups may be used. For polymer resins, a ketone such as acetone may be used. Referring now to FIG. 13, an isotropic etch is used to form an array of dull micropoint cathode emitter tips 1301 from the silicon layer 203 . If the isotropic etch were continued until the tips 1301 became sharp pointed, the mask islands 1101 might become detached from the tips 1301 and interfere with etch rate uniformity. Referring now to FIG. 14, the circular mask islands 1101 are removed with an isotropic etch that is selective for the material from which the primary masking layer 204 was formed over the silicon layer 203 . Referring now to FIG. 15, the dull-pointed micropoint cathode emitter tips 1301 formed with the isotropic etch, the results of which are depicted in FIG. 13, are sharpened with a subsequent isotropic etch to form an array of sharpened micropoint cathode emitter tips 1501 . For those familiar with etching technology, it should be clear that a mask pattern formed bybead cores 101 adhered directly on the surface of the silicon layer 203 : could not be used to form emitter tips, as an isotropic etch of such a structure would have resulted in a fairly constant material removal rate over the entire surface of silicon, as each core is supported (at least theoretically) by only a single point of silicon material having no area. If such a structure were isotropically etched, the cores would sink at a fairly constant rate as silicon material supporting each core was etched away. The sinking of the cores would eventually likely affect inter-core spacing. In any case, such non-differential removal rates would not produce a predictable pattern, much less an array of emitter tips. Thus, it is necessary to transfer the bead core pattern to an underlying laminar layer (i.e., masking layer 204 ). Each circular masking island 1101 formed from the masking layer 204 is in contact with the silicon layer 203 throughout its entire circumference. An isotropic etch of the silicon layer 203 will gradually undermine the silicon surrounding each masking island 1101 to form the pointed tip structures. In this specification and in the appended claims, a layer which is etched using the bead cores 101 as masking elements during the etch may also be referred to as the target layer. Thus, for the previously disclosed process of forming emitter tips, the masking layer 204 is also the target layer. It is, however, conceivable that there may be a need for a final structure having a pattern such as the one which was etched into masking layer 204 . Thus, for the appended claims, the target layer could be a masking layer, such as layer 204 , to which the bead core pattern is transferred during a preliminary step, or it could be a layer from which a pattern of permanent structural elements such as columns or islands is anisotropically etched. It should be evident that the heretofore described process is capable of forming an array of micropoint cathode emitter tips for a field emission display. Those having ordinary skill in the art will recognize that the process may have many other applications for creating regularly ordered mask patterns on surfaces which are so expansive that photolithography using a conventional stepper exposure apparatus is impractical. Although only several variations of the basic process are described, it will be obvious to those having ordinary skill in the art that changes and modifications may be made thereto without departing from the scope and the spirit of the process and products manufactured using the process as hereinafter claimed.

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This application is a continuation of U.S. application Ser. No. 09/268,010 that was filed with the United States Patent and Trademark Office on Mar. 15, 1999 and that issued as U.S. Pat. No. 6,440,224. U.S. application Ser. No. 09/268,010 is incorporated herein by reference. BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to the field of cleaning or brightening compositions, particularly to such compositions for use on metal surfaces, and more particularly to hydrofluoric acid generating compositions which are used in metal surface treating processes. 2. Background of the Art It is desirable to have most metal surfaces presented as a highly reflective, shiny surface, for either aesthetic benefits or for functional benefits or both. The first methods for polishing or shining the surfaces of metal were physical treatments, where abrasive surfaces or abrasive materials were rubbed against the surface of the metals to render the surface more smooth and therefore more reflective. The durability of the shininess of a metal surface varied from metal to metal because of the oxidative reactivity of the metal, or its resistance to corrosion. It is not commercially feasible to repeatedly mechanically polish surfaces to maintain their brightness, as this tends to be labor intensive, abrades the surface (removing materials and shortening the effective structural life of the article), and is very inefficient on large surfaces such as vehicles (planes, cars, trucks, snowmobiles, boats, personal water vehicles, and the like). To that end, chemical washing and polishing compositions have been developed. There are many different types of deposits and corrosion which can accumulate on metal surfaces, particularly where those surfaces are on vehicles. These deposits can also vary from location to location and from season to season as different chemicals and environmental conditions contribute to the different depositing or corroding materials. It is therefore necessary to provide a chemical composition in liquid form which has strong corrosion and film removal properties. This can make surface treatment a complex process for a number of different reasons. The cleaning or brightening solutions must be sufficiently strong to remove unwanted materials but not be so strong as to damage the underlying metal surface. Very strong solvents and strong reducing or oxidizing agents may also be potentially dangerous to workers and handlers, so that containing of the solutions prior to application and protection of workers during application is important. Hydrofluoric acid is an example of a very strong chemical used to brighten metals, especially in brightening aluminum or aluminum alloys. As shown in U.S. Pat. No. 2,687,346 aluminum and aluminum alloy surfaces on aircraft have been polished with hydrofluoric acid or hydrofluoric acid compounds. The composition of this patent particularly describes a composition which resists flowing and therefore reduces streaking of the surface of the metal by combining the hydrofluoric acid or hydrofluoric acid material with a polystyrene sulfonic acid. A sequestering agent my also be included in the composition to maintain in the cleaning solution any aluminum compounds or complexes formed in the cleaning treatment. Organic sequestering agents such as citric acid, tartaric acid, gluconic acid, and glucono delta lactone, and their ammonium salts are described. The hydrofluoric acid compound may be provided conveniently and preferably as ammonium acid fluoride both for the ease in handling the acid salt (as compared to HF itself) and for the additional contribution of the ammonium. U.S. Pat. No. 5,417,819 describes a method for forming a highly reflective surface on aluminum alloys comprising brightening a surface of an aluminum alloy body and then desmutting the freshly brightened surface in a desmutting bath. The desmutting bath comprising 10-100 volume percent nitric acid, 0.60 volume percent sulfuric acid, 0-50 volume percent water, and at least 15 grams per liter of a source of fluoride or bifluoride, such as ammonium fluoride. U.S. Pat. No. 2,625,468 describes a method for brightening aluminum and aluminum alloy surfaces in a chemical bath while maintaining the effectiveness of the chemical bath. The brightening bath generally comprises a composition of nitric acid, ammonium and hydrofluoric acid. Aluminum parts are embedded in the solution and new solution of the initial composition of the bath is added in a quantity equal to the rate of removal of materials from the bath. U.S. Pat. No. 3,326,803 describes a finely divided composition suitable for use in aqueous solution at a concentration of about 2.8 to 9.5 weight percent comprising a hydrolyzable acid fluoride salt (e.g., selected from the group consisting of alkali metal bifluorides, ammonium fluoride, sodium silicofluorides and mixtures thereof), oxalic acid, water-soluble methylcellulose, acid-stable, water-soluble wetting agents (e.g., selected from the group consisting of anionic and non-ionic wetting agents, and urea. The composition must be added to water, preferably stirred, and then applied to the metal surface to be brightened. U.S. Pat. No. 4,496,466 describes a brightening bath for aluminum derived from a wet-process phosphoric acid comprising a majority amount of ortho-phosphoric acid, a subsidiary amount of nitric acid, trace amounts of SiO 2 , chromium and copper, trace amounts of fluoride ion sufficient to maintain a phosphorous to fluorine ratio in the range of 35 to 1 to 100 to 1, trace amounts of iron, magnesium, and aluminum, less than 500 parts per million of organic substances oxidizable in the presence of nitric acid, and fume inhibitors. Because of the toxicity and difficulty in handling hydrofluoric acid compositions, phosphoric acid based compositions have found a high level of use. These phosphoric acid systems, including the ones mentioned above, may have a wide range of additional functional materials present in the baths for various specific or general purposes as shown by U.S. Pat. Nos. 2,729,551; 3,094,489; 3,009,849; 3,119,726; and 4,496,466. Some of these patents also describe combination phosphoric acid and nitric acid systems along with beneficial additives. However, purely phosphoric acid or phosphoric acid/nitric acid systems do not have some of the desirable properties of hydrofluoric acid systems. It would therefore be desirable to find hydrofluoric acid based systems which are easily used and have reduced potential for toxic exposure of the persons applying the brightening solution. SUMMARY OF THE INVENTION A two-part composition and a method for applying the two parts of the composition or an immediately mixed single part solution to a metal surface to be brightened is described. The two-part composition comprises the materials needed, when diluted and mixed, to provide hydrofluoric acid in solution for use as a brightening composition. When both components are liquids, they may be diluted and mixed as late as in a spray nozzle head and applied to the surface, with the hydrofluoric acid forming immediately, in transit to the surface, and/or on the surface to be brightened. The two components may comprise one liquid and one solid or flowable powder composition or preferably two liquid compositions which can be mixed immediately before, during or immediately after application to a surface to be brightened. One component comprises a stable fluoride providing compound and the other component comprises an acid which when in solution with the fluoride providing compound will generate hydrofluoric acid. The components are preferably mixed on the same day as they are applied, preferably within hours of application, or even within minutes of application to the surface to be cleaned. BRIEF DESCRIPTION OF THE FIGURES FIG. 1 shows examples of diluting and mixing of one or two components, 1 a ) and 1 b ), respectively, by an eductor. FIGS. 2A through D show a chart of the various ways the solutions A and B may be nixed prior to application to the substrate surface. FIG. 3 shows a way to introduce a solid component (A or B) into a liquid stream for dilution and mixing. DETAILED DESCRIPTION OF THE INVENTION Two separate components are diluted and mixed into a hydrofluoric acid generating solution or reactive mixture near the location (e.g., around the time) of application to a surface to be brightened. The dilution and mixing of the two components are done on site (near the location of use) before use (e.g., the components are preferably mixed on the same day as they are applied, preferably within hours of application, or even within minutes of application to the surface to be cleaned and even in less than 15 seconds before application), at the time of application to the surface (e.g., in a single head nozzle or multiple head nozzle), or directly on the surface to be brightened (e.g., first one component applied and then the second component applied or both at the same time). The two essential ingredients which must be present are a fluoride source and an acid solution. The invention may be practiced as simply as a) combining the fluoride source and the acid solution on site before spraying, b) combining the two sources in moving streams immediately before, during or after they pass through a spray nozzle, or c) combining the two components on the surface to be brightened in separate or contemporaneous applications from two separate streams. The fluoride source should be any water-wettable or water-soluble or acid-soluble fluoride salt or solution, such as for example, potassium fluoride, sodium fluoride, lithium fluoride, ammonium fluoride, ammonium bifluoride, sodium silicofluoride, calcium fluoride, magnesium fluoride, alkali metal fluorides and difluorides generally, alkaline metal fluorides and difluorides generally, and any other compound which forms hydrofluoric acid when combined with sulfuric, nitric, and/or phosphoric acid. The fluoride source may be provided as a solid or flowable powder to be sprayed onto the surface or mixed in a stream with the acid, but is preferably provided as a solution of the fluoride material, such as from 2 to 50% by weight fluoride salt, preferably 5 to 50% by weight fluoride salt, more preferably from 10 to 50% by weight fluoride salt on a weight basis of the solution. The acid should be a relatively strong acid, and one which in solution with the particularly selected fluoride source will generate hydrofluoric acid from that fluoride source. For example, sulfuric acid, phosphoric acid, sulfinic acid, nitric acid, phosphonic acid, hydrochloric acid, sulfamic acid and mixtures thereof will work. The acid is supplied as an aqueous solution with, for example, from 5 to 85% by weight acid, more often from 10 to 85% by weight acid, and most often between about 15 and 85% by weight acid in the solution. The diluted solution of fluoride ion can comprise about 0.01 to about 1.0% by weight fluoride salt, and can contain about 0.1 to about 0.5% by weight fluoride salt. The diluted solution of acid can comprise about 0.02 to about 2.0% by weight acid, and can comprise about 0.05 to about 1.0% by weight acid. At least one of the diluted solution of fluoride ion and the diluted solution of acid can comprise a surfactant in an amount of about 0.001 to 0.2% by weight of the solution in which it is present. At least one of the diluted solution of fluoride ion and the diluted solution of acid can comprise a quaternary ammonium compound in an amount of about 0.001 to 0.2% by weight of the solution in which it is present. Additional, optional or preferred components include, chealating agents, surfactants, metal ions, foam supressants (carbamides, dicyanoamides, triazines such as 2,4,6-triamino-s-triazine), thickening agents (e.g. methylcellulose, hydroxymethylcellulose, synthetic resins, silica), organic acids (such as oxalic acid), sulfonated polymers and the like and the basic materials in the fluoride source component (such as NaOH, KOH, ammonium compounds, and the like). These additives may be used in the relative concentrations appropriate for the particular ingredients and use. For example, the surfactants may be used in amounts of from 0.1 to 20% by weight of the concentrate (more generally from 1 to 12% by weight of the concentrate), and the foam suppressants may be used in amounts of from 0.05 to 7% by weight of the concentrate. The metal ions may be useful at much lower concentrations as for example from 0.1 to 2% by weight of the concentrate, although wider ranges for each component may be selected as needed, without limitation by these generally described ranges. Each of these may be absent from use solutions. The practice of the invention therefore includes a method of treating a surface of a metal comprising the steps of mixing an aqueous solution comprising a source of fluoride ion and an acid of sufficient strength to form hydrofluoric acid when mixed with the source of fluoride ion, and applying the solution(s), as for example by spraying the solution(s), onto a surface of metal to be treated. The mixing of the aqueous solution may be performed by mixing a first solution comprising a dissolved, water-soluble source of fluoride ion with a second solution comprising the acid. The method may comprise the steps of separately advancing a first and a second solution towards a mixing zone, mixing the first solution and the second solution within the mixing zone in a continuous flow process to form an active hydrofluoric acid-generating solution, and spraying the active solution onto a surface of metal to be treated. The mixing zone may near a spray nozzle, such as immediately before a spray nozzle. The mixing zone may be a passive mixing zone (e.g., merely a tube into which both solutions are combined while moving towards a nozzle) or an active mixing zone where turbulence, agitation, or shear forces are provided to assure mixing of the solutions. The mixing zone may also be a temporary holding tank, from which the mixed solution is drawn for spraying. The device for dilution and mixing may be any fluid direction mechanism which can combine at least two streams together before or at the time of emitting solution(s) from the mechanism, such as an injection pump, which pumps the concentrates A and B and injects them into a water stream(s) to make solution A, B or A+B. The device may be an eductor or venturi, which aspirates the concentrates and mixes them into a water stream(s) to make solution A, B or A+B. In the case where A and B are diluted separately, the two streams are combined in the mixing zone before spraying onto a surface to be treated. FIG. 1 shows examples of how an eductor may be used to dilute and mix one component at a time by aspiration (FIG. 1 a ), or two components simultaneously (FIG. 1 b ). FIGS. 2 (A-D) show a chart of the various ways in which liquid concentrates A and B may be diluted and mixed for application to a surface to be treated. The various mixing methods include: A) Mixing at least two streams, for example each of streams a) and b) which comprise a source of fluoride ion and a source of an acid of sufficient strength to form hydrofluoric acid when mixed with the source of fluoride ion. These streams may be provided independently with separate streams of water to form diluted solutions of the concentrates A and B, then combining the two diluted solutions into an active ready-for-use (or partially diluted) solution in line or through an optional holding tank, then directing the active solution to an applicator (e.g., a spray nozzle). The mixing device may be an injection pump, an aspirator, a venturi, an eductor or any other convenient mixing device. The product concentration may be further diluted in line or in the optional holding tank. B) Mixing each of streams a) and b) which comprise a source of fluoride ion and an acid of sufficient strength to form hydrofluoric acid when mixed with the source of fluoride ion, sequentially with a single stream of water to form an active ready-for-use (or partially diluted) solution, optionally storing the active solution in an optional holding tank, then directing the active solution to an applicator (e.g., a spray nozzle). The mixing device may be an injection pump, an aspirator, a venturi or an eductor. The product concentration may be further diluted in line or in the optional holding tank. C) Mixing each of streams a) and b) which comprise a source of fluoride ion and an acid of sufficient strength to form hydrofluoric acid when mixed with the source of fluoride ion. These streams may be mixed simultaneously or subsequently with a single stream of water to form an active ready-for-use (or partially diluted) solution, optionally storing the active solution in an optional holding tank, then directing the active solution to an applicator (e.g., a spray nozzle). The mixing device may be an injection pump, an aspirator, a venturi, an eductor or any other mixing device which can combine the necessary materials. The product concentration may be further diluted in line or in the optional holding tank. D) Mixing each of streams a) and b) which comprise a source of fluoride ion and an acid of sufficient strength to form hydrofluoric acid when mixed with the source of fluoride ion. The streams may be provided independently with separate streams of water to form diluted solutions of the concentrates A and B, then directing the active solutions to two applicators (e.g., a spray nozzle) for simultaneous spraying and mixing on the surface to be treated. The mixing device may be an injection pump, an aspirator, a venturi, an eductor or other mixing device. When concentrate A or B are solid blocks, the schemes of diluting and mixing shown in FIGS. 2A, 2 B and 2 D may be modified as follows. Instead of injecting or educting a liquid concentrate into an aqueous stream, a nozzle is used to spray an aqueous stream (e.g., water) on a solid concentrate block to form a diluted solution by erosion or dissolution of the solid. This is shown in FIG. 3 . This method may be used to form either A or B or both aqueous streams before proceeding toward the holding tank. In this particular format of hydrofluoric acid application, the holding tank may be needed for the solid application (as particles of material may be carried by the aqueous streams. An applicator device such as a nozzle may then be used to apply the solution from the storage tank. One particularly useful scheme is to form an acid stream by forming an aqueous acid stream, and spraying the acid stream on a solid concentrate comprising a source of fluoride ion, which has a low water solubility but a high acid solubility. This may or may not require a holding tank. When concentrate A or B or both are powders, the powder component may be either sprayed with an aqueous stream as described above for a solid block (a supporting screen or other support surface may be used here) or the powder may be added directly into the optional holding tank. The invention may also comprise a kit for the treating of a surface of a metal comprising two separate containers, a first container housing a source of fluoride ion (aqueous solution or a powder), and a second container comprising an aqueous solution of an acid having sufficient strength to form hydrofluoric acid when mixed with the source of fluoride ion, at least one of the said aqueous solutions having a surfactant dissolved therein. The system may be free of phosphoric acid. These and other aspects of the invention will be further shown and described in the following, non-limiting examples, which are not in any way intended to limit the scope or equivalents useful in the practice of the invention as broadly described. EXAMPLES The basic methodology used in these examples selects a 1×3 inch (2.5 by 7.6 cm) aluminum coupon (alloy 5052) and immerses them in a 1.0% NaOH/2.0% Versene 100 (chelant) solution. The coupons are then vigorously rubbed with a soft, non-abrasive sponge, then rinsed before immersing them in an acetone bath. The coupons were then air-dried at room temperature, and their gloss values recorded at a sixty (60) degree angle using four (4) reading each time, for each coupon, in a Gardner (BYK) Micro-TRI-gloss Gloss Meter. Two separate concentrates (concentrates A and B) were prepared as follows, with all units being as percentage by weight: Concentrate A Concentrate B 26.7% H 2 SO 4 17.0% KF 5.7% Variquat K-1215 alkoxyalkyl quaternary ammonium (cationic surfactant, bis- [polyethoxy ethanolo]coco ammonium chloride, Witco Chemical Co.), and 3.3% NPE 9.5 (Nonyl phenol ethoxylate with an average ethylene oxide content of 9.5 moles) Solutions A and B were then prepared from Concentrates A and B, respectively, by dilution and mixing into distilled water to give a final concentration of 0.25% of the concentrates. The data sets used the following compositions as the brightening solution in practicing the method of the examples. Set (A) comprised Solution (A) Set (B) comprised Solution (B) Set (C) comprised an equal parts mixture of Solution (A) and Solution (B). The two solutions were mixed and allowed to equilibrate for 15 minutes before being sprayed as a single stream of solution. Set (D) was applied as two separate sprayers applied equal amounts of Solutions (A) and (B) with mixing of the two solutions when the two sprays overlapped in the air and collided simultaneously or mixed (on the aluminum coupon surface) with the aluminum coupon surface. Set (E) was sprayed from a single sprayer, using equal amounts of each of Solution (A) and Solution (B). The mixing was assumed to occur when the two solutions were drawn up symmetrically into a single tube after and concurrently when the solution exited the spray nozzle. Set (F) used distilled water as a control. It was sprayed, as were all other solutions, using an aerosolizing spout. After spraying, each coupon was immediately laid horizontally and allowed to lay horizontal for twelve (12) minutes, after which each coupon was immersed twice in hot tap water, and then dunked into acetone. Each coupon was air dried for six (6) minutes. The coupons were then again measured for gloss at a sixty (60) degree angle, and the data recorded. The difference in gloss before and after treatment was then calculated to provide a delta gloss value, reported in the Table as Avg. Delta Gloss. The results evidence the following conclusions. Sets C, D and E which combined Solutions (A) and (B) displayed better results than either individual Set using only one of Solutions (A) or (B) and Set (F) where only water was used. The performance of Set (D) where the solutions were believed to mix and react on the surface of the coupons was apparently higher than where the solutions were mixed in the nozzle (E) and where the solutions were premixed (C). This is particularly surprising in that one might infer from the respective data between Sets (C) and (E) that there might be some equilibration time desired for complete formation of the hydrofluoric acid from the components, because the equilibrated solution was marginally (possibly within the limits of experimental error) higher than Set (E) where the solutions mixed in the nozzle. The fact that some equilibration time might be desirable, and the fact that mixing of the separate solutions in air, in transit to the coupon surface, and/or on the coupon surface provided statistically significant improved results is definitely surprising. The main objective of safe handling of the active solution by forming the hydrofluoric acid on site shortly before applying the active solution to the surface to be treated is not performed at the expense of the effectiveness of the cleaning solutions. The data are tabulated in Table 1, showing On-Surface/In-Nozzle HF Generation and Aluminum Brightening. The combination of solutions described above in the examples, with 5-30% fluoride salt, 15-40% sulfuric acid, and 0% or 0.5% to 10% by weight of organic quaternary ammonium compounds has been found to be particularly useful. The compositions may consist essentially of those two or three basic ingredients and may have levels of other acids (e.g., less than 5%, less than 3%, less than 1% or none) such as nitric acid and phosphoric acid. In the practice of the present invention, where the mixing of the solutions is described as near the applicator or spray nozzle, this means that there is only a single conveying means (tube or pipe) in place between the point of mixing and the applicator, or that the mixing is actually effected after the spraying (in the air in transit to the surface dr on the surface). These and other non-limiting examples of the invention are provided herein. TABLE 1 On-Surface/In-Nozzle HF Generation and Aluminum Brightening 60 deg Gloss by Gardner BYK Gloss Meter Before HF treatment After HF treatment Difference Avg std dev Avg std dev Gloss (n = 4) (n = 4) (n = 4) (n = 4) (n = 4) Average (Solution A only) 3.28 Sulfuric + Surfs A1 182.9 5.8 189.6 4.4 6.7 A2 159.7 2.6 160.6 3.2 0.9 A3 142 4 142.6 4.8 0.6 A4 158.8 1 163.5 1.2 4.7 A5 137 5.8 140.5 4.6 3.5 (Solution B only) −1.84 KF B1 153.9 3.2 156 3.8 2.1 B2 156.6 6.4 152.3 5 −4.3 B3 171.7 6.4 169 8 −2.7 B4 156.6 6.6 150.8 7.2 −5.8 B5 170.4 3.4 171.9 4.8 1.5 A + B Pre-Equil. 10.73 C1 159.7 1.4 170.7 1 11 C2 163.7 2.2 170.2 1.6 6.5 C4 139.5 3.2 151.7 2.8 12.2 C5 150.7 1.6 163.9 0.8 13.2 A + B On Surface Mixing 12.60 D1 150 5.4 161.2 5.4 11.2 D2 145.7 5 159.5 5 13.8 D3 163 7.4 182 5.8 19 D4 137.9 2.4 155.1 1.6 17.2 D5 164.8 1.2 166.6 2 1.8 A + B in-nozzle Mixing 10.53 E1 172.6 2.6 178.6 2 6 E2 155.1 2.4 162.2 1.2 7.1 E3 166 4.8 184.5 1 18.5 Water Control 1.36 F1 176.5 2.2 180.1 6.2 3.6 F2 130.6 6.4 127.4 5 −3.2 F3 158.4 8.6 163.3 3 4.9 F4 145.3 6.4 144.3 6.6 −1 F5 167.4 4.8 169.9 2.2 2.5 Note: See text for contents of Solutions A and B.

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BACKGROUND OF THE INVENTION Field of the Invention This invention relates to a process for polymerizing fluoroolefins in the gas phase. References Polymerization of tetrafluoroethylene (TFE) in the gas phase in the presence of nonvolatile initiators is known. For example, U.S. Pat. No. 3,592,802 discloses gaseous polymerization of TFE at about 40° to 120° C. in the presence of selected di(saturated hydrocarbyl) peroxydicarbonates such as diisopropylperoxydicarbonate, preferably supported on a suitable carrier material such as polytetrafluoroethylene. U.S. Pat. No. 3,304,293 discloses gas phase polymerization of TFE employing heat-activated gels of silica or silica-alumina admixed with salts of oxy acids of hexavalent chromium, such as magnesium chromate. U.S. Pat. No. 3,170,858 discloses gaseous polymerization of TFE, or copolymerization thereof with minor amounts of other fluoroolefins such as hexafluoropropene or vinylidene fluoride, in the presence of previously irradiated TFE homopolymer. Use of nonvolatile initiators, including fluorinated oligomers, in condensed phase polymerization of TFE is also known. For example, U.S. Pat. No. 3,493,530 discloses polymerization of perfluorinated olefins in the presence of macromolecular perfluorinated polyperoxides of the formula (C 3 F 6 O x ) n wherein n is an integer of 5 to 100, the initiators being soluble in the liquid polymerization media. The use of TFE/ether- or HFP/ether-peroxide copolymers which are nonvolatile oils as initiators for fluoroolefin polymerization is disclosed in Dutch Application No. 6,711,121. U.S. Pat. No. 2,598,283 discloses copolymerization of TFE and HFP employing bis-trichloroacetyl peroxide at low temperatures in a prehalogenated hydrocarbon solvent. U.S. Pat. Nos. 4,535,136 and 4,588,796 disclose solution polymerization of fluoroolefins employing acyl hypofluorite initiators of the formula RCOOF or X(CF 2 ) n COOF wherein R is X(CF2)n- or CF 3 CF 2 CF 2 O[CF(CF 3 )CF 2 O] m CF(CF 3 )-, X is H or F, m is 0 to 50 and n is 1 to 16. U.S. Pat. No. 2,753,329 discloses gaseous polymerization of TFE employing peroxide and peracetate catalysts which reportedly produce a fluidizable, powdery polymer which does not adhere to the reactor walls. Polymerization is carried out at a temperature of about 125° to about 200° C. and a pressure of at least 100 psi (690 kPa). Under these process conditions, more than 99% of the catalyst is said to be present in the vapor phase. Prior art processes for polymerizing fluoroolefins in the gas phase sometimes employ inert gases or vapors as heat transfer media to remove heat of polymerization. Although recycle of monomers has not been reported for cooling fluoroolefin polymerization, recycle has been employed with non-halogenated monomers. U.S. Pat. No. 4,525,547 discloses recycle of unreacted monomers through external heat exchangers to remove heat of polymerization in the gas phase polymerization of ethylene. Copolymerization of ethylene with other α-olefins employing a non-volatile (liquid or solid) coordination catalyst, an inert gaseous hydrocarbon diluent, and recycle of unreacted monomers through an external heat-exchanger is disclosed. The process reportedly results in, among other things, "reduced polymer deposition on the inner wall of the polymerization vessel, the prevention of lumpy polymer formation, and the proceeding of uniform copolymerization reaction". In most, if not all, gas phase fluoroolefin polymerization processes of the art, reactor fouling and plugging is a major problem, requiring frequent and costly shutdowns. The present invention provides a continuous gas phase fluoroolefin polymerization process that substantially avoids fouling and plugging of polymerizer equipment and provides a free-flowing particulate fluoropolymer product of high stability. SUMMARY OF THE INVENTION This invention provides a process for preparing fluorinated polymers comprising (co)polymerizing at least one gaseous fluoroolefin monomer (fuoromonomer) in the presence of a non-volatile halogenated initiator, said process being further characterized in that heat is removed primarily by recycling initiator-free polymerizer gases through an external cooler (heat exchanger). The process avoids fouling of the polymerizer and the cooler by agglomerated polymer; facilitates trouble-free continuous operation; and provides a free-flowing particulate product of high quality. Preferably at least one fluoromonomer is perfluorinated. Optionally, gases which are inert under polymerization conditions may be used as diluents, and gaseous chain-transfer agents may also be employed as desired to control moleculare weight. DETAILED DESCRIPTION OF THE INVENTION Heat removal in the polymerization of fluoroolefins is especially important for safe control of the reaction. For example, the heat of polymerization of TFE is 37 kcal/mole as compared with 23 kcal/mole for ethylene and 21 kcal/mole for propylene. In the present process, heat of polymerization is effectively removed by continuously recycling a portion of the polymerizer gases through an external heat exchanger. Initiators commonly used in the free-radical polymerization of fluoroolefins, such as perfluoropropionyl peroxide, are relatively volatile and would therefore be present in the recycle gases and result in polymerization therein, with subsequent particle agglomeration and fouling. In the present process, a non-volatile initiator which cannot enter the recycle stream is employed. Consequently, polymerization on, and fouling of, cooled heat exchanger surfaces is avoided. Continuous polymerization for long periods of time without fouling of the heat exchanger of the reactor has been achieved using the process of the invention. Use of selected reactive, non-volatile initiators which permits polymerization at relatively low temperatures is especially preferred in the present process. Such initiators further assist polymerization heat control, but more importantly, provide a fluoropolymer product of high thermal stability in many cases. Certain fluoromonomers, for example, perfluoropropylvinyl ether, a preferred comonomer, undergo chain transfer reactions during polymerization which generate undesirable (thermally unstable) acyl fluoride end groups. Such chain transfer reactions increase with increasing temperature. Thus, such monomers should preferably be polymerized at relatively low temperatures, normally below about 100° C., preferably below about 60° C. Removal of polymerization heat while maintaining adequate productivity at these lower temperatures is most effectively achieved by monomer recycle through an external heat exchanger. The present process can be operated in a temperature range of about 30° to about 200° C., preferably about 40° to about 80° C. Reactor pressure may be in the range of about 50 to about 1000 psi (345-6900 kPa), preferably about 200 to about 400 psi (1380-2760 kPa); Monomer pressure will normally account for most of the total reactor pressure. Fluoroolefins operable in the present process will in general be those which are homopolymerizable or copolymerizable by a free-radical mechanism. Such fluoromonomers include perfluoroolefins, particularly tetrafluoroethylene (TFE), perfluoroalkylvinyl ethers (C 1-4 alkyl), perfluoropropene, perfluoro-2,2-dimethyldioxole, perfluoro-2-methylene-4-methyl-1,3-dioxolane, and partially fluorinated monomers, particularly vinylidene fluoride, trifluoroethylene, chlorotrifluoro-ethylene and perfluorobutylethylene. Copolymerization of fluoroolefins, especially TFE, with other halogenated or non-halogenated monomers such as ethylene, is a preferred embodiment of this invention. Especially preferred is the copolymerization of TFE and perfluoropropylvinyl ether (PPVE) wherein the weight ratio of TFE to PPVE is at least 9 to 1. Initiators which are suitable for use in the present process are non-volatile (i.e. negligible vapor pressure under polymerization conditions) free-radical sources. Preferred initiators are perhalogenated, most preferably perfluorinated, initiators. Non-volatile perfluoroether peroxides, such as those formulated below in Control Experiment B, wherein n is greater than 2, or those having the structure [CF 3 (CF 2 ) n COO] 2 wherein n is greater than 8, or [CCl 3 C00] 2 , are especially suitable. Diluent vapors which are inert under polymerization conditions may optionally be employed. Suitable diluents include inert gases such as carbon dioxide, nitrogen or helium, or fluorinated saturated compounds such as sulfur hexafluoride, tetrafluoromethane or hexafluoroethane. Use of chain transfer agents is also contemplated when lower or controlled molecular weight polymers are desired. Suitable agents include vapors having weakly exchangeable hydrogen or halogen atoms. Examples are hydrogen, methyl chloride or trifluoroacetylchloride. In the following experiments and example, parts are by weight and temperatures are in degrees Celsius unless otherwise indicated. Control Experiment A shows, in monomer recycle cooling, that series fouling occurs when a volatile initiator is used. Control Experiment B shows that fouling is greatly reduced, but not eliminated, when an only slightly volatile initiator is used. The Example demonstrates the complete absence of fouling when a non-volatile initiator is employed in the process of the invention. DESCRIPTION OF DRAWING A schematic flow diagram is shown in the attached figure. A 300 cc glass pressure vessel 11 was used as a reactor, allowing visual observation of polymerization in progress. A bed of finely divided polymer 12 within the reactor was agitated mechanically with impeller 13. Alternatively, the bed could be agitated by fluidization with recycle gases. The vapor phase was taken overhead to a cyclone 14 (also glass for easy observation) to remove polymeric particulates, passed through blower 15 to heat exchanger 16 (an air cooled metal tube) to remove heat of reaction, and then returned to the reactor. As polymerization proceeded, monomers were replaced via feed tube 17. Initiators were added as solutions in inert solvents such as "Freon" 113or "FC"-75 via tube 18. Solid polymeric product was removed from the reactor through lock hopper 19 consisting of two ball valves with a storage pressure let down space in between. The reactor system outlined above is exemplary and not meant to be limited to the particular mechanics of monomer and initiator introduction, product agitation, gas recycle and cooling, and product removal shown. The process of the present invention essentially provides a means for removing polymerization heat by monomer recycle while avoiding fouling of equipment with polymeric deposits. CONTROL EXPERIMENT A Heavy Fouling/Volatile Initiator The reactor was loaded with 15 g of granular TFE/Perfluoropropylvinyl ether (PPVE) copolymer, 100 psig (6900 kPa) nitrogen, 200 psig (1380 kPa) TFE (300 psig (2070 kPa) total), and PPVE until the vapor phase analysed 77% TFE, 8% PPVE, and 15% nitrogen by gas phase chromatography. The reactor was heated to 90°-100°C.; the mechanical stirrer started at 205 rpm; gas started circulating gently though the recycle loop; and then a "Freon" 113 solution of 0.21M perfluoropropionyl peroxide initiator was injected at 2 to 3 mL/h as needed. Within 22 minutes a light buildup of polymer was noticeable on the walls of the cyclone. After 33 minutes, polymer buildup threatened to close the exit line of the reactor. Initiator feed had to be discontinued after 105 minutes. The equipment was shut down and inspected. Parts of the cyclone had 1/16" (1.6 mm) thick deposits of polymer, and the cyclone further retained several large sheets of polymer that appeared to have been detached from a surface. A total of 48.9 grams of new polymer were recovered from the reactor and associated parts. CONTROL EXPERIMENT B Trace Fouling/Slightly Volatile Initiator The reactor was loaded with 151.1 g of TFE/PPVE copolymer, 100 psig (690 kPa) nitrogen, 200 psig (1380 kPa) TFE (300 psig (2070 kPa) total), and PPVE to bring the gas phase to 79% TFE, 6% PPVE, and 15% nitrogen. The reactor was heated to 80° C.; the impeller started; and the gas phase gently recirculated. Initiator solution: 0.097M of the initiator of Formula 1* where n=1 in "Freon" 113, was injected at 7.5 mL/h. Fifty minutes into the run a small amount of polymer could be seen on the walls of the cyclone as small particulates. After 122 minutes, the initiator feed was stopped and the reactor shut down and inspected. The cyclone was largely clean except for some spotty particulates running along about 1" of the upper surface. A total of 49.7 g of TFE/PPVE copolymer was made for a productivity of 0.7 lbs/gallon-hour (83.9 kg/m 3 -h) and a polymer production of 14,500 g of polymer/g mole of radicals. * Formula 1 is {CF 3 CF 2 CF 2 O[CF(CF 3 )CF 2 O] n CF(CF 3 )COO} 2 EXAMPLE No Fouling/Non-volatile Initiator The reactor was loaded with 163.9 g of TFE/PPVE copolymer, 100 psig (690 kPa) of nitrogen, 200 psig (1380 kPa) of TFE (300 psig (2070 kPa) total), and PPVE to bring the gas phase to 80 wt percent TFE, 7% PPVE, and 13% nitrogen. The reactor was heated to 84° C., the impeller was started, and the gas phase gently recirculated as the initiator, 0.088M of Formula 1* where n=5.9, in "Freon" 113 was added first at 5.0 mL/h and then at 7.5 mL/h. Recirculation continued smoothly for 99 minutes with no visible deposit on the walls of the cyclone. Recirculation was terminated and the reactor was shut down 37 minutes later. The cyclone, the walls of the reactor, and the impeller were all essentially free of adherent polymer. A total of 43.0 g of new polymer were made in this run for a productivity of 0.49 lbs/gallon-hour (58.7 kg/m 3 -h) and a polymer production of 15,500 grams/gm mole of radicals.

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CROSS REFERENCE TO RELATED APPLICATIONS [0001] The present application is based on, and claims priority from Taiwan Application Serial Number 102125685, filed on Jul. 18, 2013, and claims the benefit of U.S. Provisional Application No. 61/813,445, filed on Apr. 18, 2013, the entirety of which are incorporated by reference herein. TECHNICAL FIELD [0002] The technical field relates to nano metal wire, and in particular, relates to a method for manufacturing the same. BACKGROUND [0003] Recently, nano technology is widely used in information technology, material technology, biotechnology, and the likes. When the size of a material is scaled down to nano scale, its properties will change according to its shape and size. For example, a silver nanorod or nanowire may have absorption peaks of longitudinal mode and traverse mode under surface plasmon resonance. The nanorod or nanowire with a larger aspect (length-diameter) ratio has a red-shifted absorption peak of longitudinal mode. [0004] A silver nanowire or silver wire with a high aspect ratio has been disclosed by some research teams. However, the conventional silver nanowires have a length of several nanometers (nm) to several micrometers (μm), an aspect ratio of less than 1000 (or even less than 100), and low conductivity. [0005] Accordingly, a novel method for preparing silver nanowires with high conductivity and a high aspect ratio is called-for. SUMMARY [0006] One embodiment of the disclosure provides a method of manufacturing a nano metal wire, comprising: putting a metal precursor solution in a core pipe of a needle; putting a polymer solution in a shell pipe of the needle, wherein the shell pipe surrounds the core pipe; applying a voltage to the needle while simultaneously jetting the metal precursor solution and the polymer solution to form a nano line on a collector, wherein the nano line includes a metal precursor wire surrounded by a polymer tube; chemically reducing the metal precursor wire of the nano line to form a nano line of a nano metal wire surrounded by the polymer tube; and washing out the polymer tube by a solvent. [0007] One embodiment of the disclosure provides a nano line, comprising: a metal precursor wire; and a polymer tube surrounding the metal precursor wire, wherein the metal precursor wire comprises a metal compound and a chemically reducing agent. [0008] One embodiment of the disclosure provides a nano metal wire, having an aspect ratio of greater than 1000, and a conductivity of between 10 4 S/m to 10 7 S/m. [0009] A detailed description is given in the following embodiments with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS [0010] The disclosure can be more fully understood by reading the subsequent detailed description and examples with references made to the accompanying drawings, wherein: [0011] FIG. 1 shows an electrostatic spinning apparatus for manufacturing nano metal wires in one embodiment of the disclosure; [0012] FIG. 2 illustrates a cross-sectional view of a shell pipe and a core pipe of a needle in one embodiment of the disclosure; [0013] FIG. 3 shows a nano line in one embodiment of the disclosure; [0014] FIG. 4 shows a nano metal wire in one embodiment of the disclosure; [0015] FIG. 5 shows absorption spectra of nano silver wires without annealing or after annealing for different periods of time in some embodiments of the disclosure; [0016] FIG. 6 shows absorption spectra of nano silver wires left to stand at room temperature for different periods of time or annealing for different periods of time in some embodiments of the disclosure; and [0017] FIG. 7 shows an XRD spectrum of nano silver wires in one embodiment of the disclosure. DETAILED DESCRIPTION [0018] In the following detailed description, for purposes of explanation, numerous specific details are set forth in order to provide a thorough understanding of the disclosed embodiments. It will be apparent, however, that one or more embodiments may be practiced without these specific details. In other instances, well-known structures and devices are schematically shown in order to simplify the drawing. [0019] In the disclosure, a nano metal wire having a high aspect ratio (e.g. greater than 1000) is formed by an electrostatic spinning apparatus. As shown in FIG. 1 , a polymer solution is put into a syringe 11 , and a metal precursor solution is put into a syringe 13 . The syringe 11 connects to a shell pipe 15 O of a needle 15 , and the syringe 13 connects to a core pipe 15 I of the needle 15 , respectively. As shown in FIG. 2 , the shell pipe 15 O and the core pipe 15 I are concentric cylinders. A voltage is then applied to the needle 15 while simultaneously jetting the metal precursor solution and the polymer solution from the needle 15 , thereby forming a nano line 17 on a collector 19 . As shown in FIG. 3 , the nano line 17 includes a metal precursor wire 17 A surrounded by a polymer tube 17 B. The described process of forming the nano line 17 is the so-called electrostatic spinning method. [0020] In one embodiment, a solvent of the polymer solution is an organic solvent with high-polarity such as methanol or acetone, and the corresponding polymer is polyvinylpyrrolidone (PVP). In addition, a salt such as tetrabutyl ammonium phosphate (TBAP) or cetyltrimethylammonium bromide (CTAB) can be optionally added into the polymer solution. The salt may enhance the polarization degree of the electrostatic spinning, thereby reducing the polymer amount. [0021] In one embodiment, the additive amount of the salt is of about 1 mg/mL to 100 mg/mL. Alternatively, a solvent of the polymer solution can be an organic solvent with low-polarity such as tetrahydrofuran (THF), toluene, or chloroform. In this case, the corresponding polymer can be polyacrylonitrile (PAN), polyvinyl alcohol (PVA), or ethylene vinyl alcohol (EVA). If the solvent of the polymer solution is an organic solvent with high-polarity, it can be washed out by water to meet environmentally friendly requirements after the forming of a nano metal wire. If the solvent of the polymer solution is an organic solvent with low-polarity, the polymer solution and the metal precursor solution will be immiscible when forming the nano metal wire having a high quality. In one embodiment, the polymer in the polymer solution has a concentration of about 100 mg/mL to 200 mg/mL. [0022] In one embodiment, the metal precursor solution includes a metal compound and chemically reducing agent. The metal compound can be a silver compound (e.g. silver nitrate or silver oxide), platinum compound (e.g. platinum chloride or platinous oxide), gold compound (e.g. gold chloride or auric acid), or combinations thereof. The selection of the chemically reducing agent depends on the metal compound type. For example, when the metal compound is silver nitrate, the chemically reducing agent can be ethylene glycol. When the metal compound is silver oxide, the chemically reducing agent can be ammonium hydroxide. When the metal compound is platinum chloride, the chemically reducing agent can be hydrazine, sodium hydroborate, hydrogen, or alcohol. When the metal compound is gold chloride, the chemically reducing agent can be an aqueous solution of sodium citrate or Vitamin C. The metal compound concentration depends on the metal compound type. For example, the silver nitrate has a concentration of about 1 mg/mL to 100 mg/mL, and the silver oxide has a concentration of about 1 mg/mL to 100 mg/mL. The chemically reducing agent concentration depends on the chemically reducing agent type. For example, the ethylene glycol may directly serve as an organic solvent with high-polarity, and the ammonium hydroxide may have a concentration of about 1 wt % to 50 wt %. [0023] In one embodiment, the core pipe 15 I of the needle 15 has a diameter of about 0.5 m to 2 mm, which is determined by the desired diameter of the nano metal wire. In one embodiment, the shell pipe 15 O and the core pipe 15 I of the needle 15 have a difference of about 0.01 mm to 5 mm. [0024] In one embodiment, the voltage applied to the needle 15 is about 10 kV to 12 kV. In one embodiment, a tip of the needle 15 and the collector 19 have a distance therebetween of about 5 cm to 50 cm. If the collector 19 is a common plate, random arranged nano lines 17 will be easily formed. If the collector 19 is parallel electrode plate, parallel arranged nano lines 17 will be formed. [0025] In one embodiment, the syringes 11 and 13 are controlled by syringe pumps 12 and 14 , respectively, to tune flow rates of the polymer solution and the metal precursor solution. For example, the polymer solution is jetted out of the needle 15 with a flow rate of about 0.1 mL/hr to 5 mL/hr, and the metal precursor solution is jetted out of the needle 15 with a flow rate of about 0.01 mL/hr to 1 mL/hr. [0026] After the described steps, the nano lines 17 can be left at room temperature under the regular atmosphere, such that the metal compound is slowly chemically reduced by the chemically reducing agent in the metal precursor wires 17 A. As a result, nano metal wires 21 are obtained. In one embodiment, the nano lines 17 can be annealed under the atmosphere to accelerate chemical reduction. For example, the anneal step can be performed at a temperature of about 100° C. to 200° C. A suitable solvent can be adopted to wash out the polymer tube 17 B surrounding around the nano metal wire 21 . For example, when the polymer tube 17 B is PVP, it can be washed out by water, and the nano metal wires 21 in FIG. 4 are left. When the polymer tube 17 B is PAN, it can be washed out by THF. The nano metal wire 21 prepared by the described steps has a diameter of 50 nm to 500 nm, an aspect ratio of greater than 1000, and a conductivity of about 10 4 S/m to 10 7 S/m. Note that the nano metal wire 21 has an unlimited maximum length. In other words, the nano metal wire has an unlimited maximum aspect ratio. In one embodiment, the nano metal wire 21 may have a centimeter-scaled length, e.g. at least 1 cm or even at least 10 cm. The nano metal wire 21 can be applied to an anti-EMI paint, an RFID device, a solar cell conductive paste, a long-lasting and anti-bacterial peelable spray, and a transparent conductive film, and the likes. [0027] Below, exemplary embodiments will be described in detail with reference to the accompanying drawings so as to be easily realized by a person having ordinary knowledge in the art. The inventive concept may be embodied in various forms without being limited to the exemplary embodiments set forth herein. Descriptions of well-known parts are omitted for clarity, and like reference numerals refer to like elements throughout. EXAMPLES [0028] In following examples, the needle had a shell pipe with a diameter of 1.25 mm and a core pipe with a diameter of 0.95 mm. The needle and the parallel electrode collector plate had a distance of 13 cm therebetween. The voltage applied to the needle was 10 kV. One electrode plate of the parallel electrode collector plate was electrically connected to ground, and another electrode plate was electrically connected to a voltage of 1 kV. Diameters of the nano lines and the nano metal wires were all measured by transmission electron microscopy (TEM, JEOL JEM-2100F). Example 1 [0029] An ethylene glycol solution of silver nitrate (30 mg/mL) was put into a syringe connected to a core pipe of a needle. A methanol solution of PVP (200 mg/mL) was put into another syringe connected to a shell pipe of the needle. The silver precursor solution in the core pipe was controlled by a syringe pump to have a flow rate of 0.1 mL/hr, and the polymer solution in the shell pipe was controlled by another syringe pump to have a flow rate of 1 mL/hr. A nano line having a diameter of about 2.2 μm was electrostatically spun. [0030] The nano line was annealed at 150° C. under the atmosphere for about 8 minutes, and then washed by water to remove the polymer tube. As such, a nano silver wire with a diameter of about 500 nm, a length of about 10 cm, and an aspect ratio of 200000 was obtained. The nano silver wire was measured by a spectrometer to obtain its absorption spectrum as shown in FIG. 5 . Example 2 [0031] Similar to Example 1, the difference in Example 2 was the annealing period being changed to about 20 minutes. After annealing, the nano line was washed by water to remove the polymer tube. As such, a nano silver wire with a diameter of about 500 nm, a length of about 10 cm, and an aspect ratio of 200000 was obtained. The nano silver wire was measured by a spectrometer to obtain its absorption spectrum as shown in FIG. 5 . Example 3 [0032] Similar to Example 1, the difference in Example 3 was the annealing period being changed to about 10 hours. After annealing, the nano line was washed by water to remove the polymer tube. As such, a nano silver wire with a diameter of about 500 nm, a length of about 10 cm, and an aspect ratio of 200000 was obtained. The nano silver wire was measured by a spectrometer to obtain its absorption spectrum as shown in FIG. 5 . Comparative Example 1 [0033] Similar to Example 1, the difference in Comparative Example 1 was the nano line having a diameter of 2.2 μm being directly washed by water to remove the polymer tube (without any annealing). The silver precursor wire was measured by a spectrometer to obtain its absorption spectrum as shown in FIG. 5 . [0000] TABLE 1 Annealing Nano silver Nano silver period at wire Nano silver wire aspect 150° C. diameter wire length ratio Example 1  8 minutes ~500 nm 10 cm 2 × 10 5 Example 2 20 minutes ~500 nm 10 cm 2 × 10 5 Example 3 10 hours ~500 nm 10 cm 2 × 10 5 Comparative Without none none none Example 1 annealing [0034] As shown in FIG. 5 and Table 1, the absorption peaks at about 420 nm of the nano silver wires were higher and red-shifted as the length of the annealing periods were increased. Accordingly, the annealing step was beneficial for chemically reducing the silver nitrate to silver. Example 4 [0035] An ammonium hydroxide solution of silver oxide (with a silver oxide concentration of 5 mg/mL and an ammonium hydroxide concentration of 33%) was put into a syringe connected to a core pipe of a needle. A methanol solution of PVP (200 mg/mL) was put into another syringe connected to a shell pipe of the needle. The silver precursor solution in the core pipe was controlled by a syringe pump to have a flow rate of 0.01 mL/hr, and the polymer solution in the shell pipe was controlled by another syringe pump to have a flow rate of 1 mL/hr. A nano line having a diameter of about 1 μm was electrostatically spun. The nano line was left to stand at room temperature under the atmosphere for 4 hours, and then washed by water to remove the polymer tube. As such, a nano silver wire with a diameter of about 300 nm and a length of 10 cm was obtained. The nano silver wire was measured by a spectrometer to obtain its absorption spectrum as shown in FIG. 6 . Example 5 [0036] Similar to Example 4, the difference in Example 5 was the nano line being left to stand at room temperature under the atmosphere for 4 days. Thereafter, the nano line was washed by water to remove the polymer tube. As such, the nano silver wire with a diameter of about 300 nm and a length of 10 cm was obtained. The nano silver wire was measured by a spectrometer to obtain its absorption spectrum as shown in FIG. 6 . Example 6 [0037] Similar to Example 4, the difference in Example 6 was the nano line having a diameter of about 1 μm being annealed at 200° C. under the atmosphere for 10 minutes. Thereafter, the nano line was washed by water to remove the polymer tube. As such, the nano silver wire with a diameter of about 300 nm and a length of 10 cm was obtained. The nano silver wire was measured by a spectrometer to obtain its absorption spectrum as shown in FIG. 6 . Example 7 [0038] Similar to Example 6, the difference in Example 7 was the nano line being annealed at 200° C. for 20 minutes. Thereafter, the nano line was washed by water to remove the polymer tube. As such, the nano silver wire with a diameter of about 300 nm and a length of 10 cm was obtained. The nano silver wire was measured by a spectrometer to obtain its absorption spectrum as shown in FIG. 6 . Example 8 [0039] Similar to Example 6, the difference in Example 8 was the nano line being annealed at 200° C. for 30 minutes. Thereafter, the nano line was washed by water to remove the polymer tube. As such, the nano silver wire with a diameter of about 300 nm and a length of 10 cm was obtained. The nano silver wire was measured by a spectrometer to obtain its absorption spectrum as shown in FIG. 6 . [0000] TABLE 2 Nano Nano silver silver Nano silver Anneal wire wire wire aspect temperature/period diameter length ratio Example 4 Room temperature/ ~300 nm 10 cm 3.3 × 10 5 4 hours Example 5 Room temperature/ ~300 nm 10 cm 3.3 × 10 5 4 days Example 6 200° C./10 minutes ~300 nm 10 cm 3.3 × 10 5 Example 7 200° C./20 minutes ~300 nm 10 cm 3.3 × 10 5 Example 8 200° C./30 minutes ~300 nm 10 cm 3.3 × 10 5 [0040] As shown in FIG. 6 and Table 2, the nano silver wires were formed by only being left to stand at room temperature for a long period without annealing. However, the anneal step may accelerate the forming of the nano silver wires. The nano silver wire having a diameter of 300 nm and a length of 10 cm was formed by annealing at a temperature of 200° C. for a period of 10 minutes (longer annealing period was not needed). The nano silver wire had a conductivity of 6.9×10 4 S/m. Example 9 [0041] An ammonium hydroxide solution of silver oxide (with a silver oxide concentration of 1 mg/mL and an ammonium hydroxide concentration of 33%) was put into a syringe connected to a core pipe of a needle. A methanol solution of PVP and TBAP (with a PVP concentration of 100 mg/mL and a TBAP concentration of 10 mg/mL) was put into another syringe connected to a shell pipe of the needle. The silver precursor solution in the core pipe was controlled by a syringe pump to have a flow rate of 0.01 mL/hr, and the polymer solution in the shell pipe was controlled by another syringe pump to have a flow rate of 1 mL/hr. A nano line having a diameter of about 0.6 μm and a length of 10 cm was electrostatically spun. The nano line was annealed at 200° C. under the atmosphere for 20 minutes, and then washed by water to remove the polymer tube. As such, a nano silver wire with a diameter of about 357 nm was obtained. Example 10 [0042] An ammonium hydroxide solution of silver oxide (with a silver oxide concentration of 5 mg/mL and an ammonium hydroxide concentration of 33%) was put into a syringe connected to a core pipe of a needle. A methanol solution of PVP and TBAP (with a PVP concentration of 100 mg/mL and a TBAP concentration of 10 mg/mL) was put into another syringe connected to a shell pipe of the needle. The silver precursor solution in the core pipe was controlled by a syringe pump to have a flow rate of 0.01 mL/hr, and the polymer solution in the shell pipe was controlled by another syringe pump to have a flow rate of 1 mL/hr. A nano line having a diameter of about 0.7 μm and a length of 10 cm was electrostatically spun. The nano line was annealed at 200° C. under the atmosphere for 20 minutes, and then washed by water to remove the polymer tube. As such, a nano silver wire with a diameter of about 464 nm was obtained. As known by comparison with Example 9, a nano silver wire having a larger diameter can be obtained through a higher silver oxide concentration. Example 11 [0043] An ammonium hydroxide solution of silver oxide (with a silver oxide concentration of 1 mg/mL and an ammonium hydroxide concentration of 33%) was put into a syringe connected to a core pipe of a needle. A methanol solution of PVP and TBAP (with a PVP concentration of 100 mg/mL and a TBAP concentration of 30 mg/mL) was put into another syringe connected to a shell pipe of the needle. The silver precursor solution in the core pipe was controlled by a syringe pump to have a flow rate of 0.01 mL/hr, and the polymer solution in the shell pipe was controlled by another syringe pump to have a flow rate of 1 mL/hr. A nano line having a diameter of about 0.4 μm and a length of 10 cm was electrostatically spun. The nano line was annealed at 200° C. under the atmosphere for 20 minutes, and then washed by water to remove the polymer tube. As such, a nano silver wire with a diameter of about 285 nm was obtained. As known by comparison with Example 9, a nano silver wire having a smaller diameter can be obtained through a higher TBAP concentration. [0044] The nano silver wire in Example 11 had a resistivity of 4.3×10 −4 Ω·cm. A bulk silver had a resistivity of 1.6×10 −6 Ω·cm (See Applied Physics Letters 95, 103112, 2009). A single crystalline nano silver wire had a resistivity of 2.19×10 −4 Ω·cm (See Applied Physics Letters 95, 103112, 2009). A poly crystalline nano silver wire had a resistivity of 8.29×10 −4 Ω·cm (See Nano letter, Vol. 2, No. 2, 2002). Accordingly, the nano silver wire prepared in Example 11 of the disclosure should be a single crystalline nano silver wire. An XRD spectrum of the nano silver wire is shown in FIG. 7 . The nano silver wire had a single crystalline face-centered cubic structure, as determined by TEM and XRD. Also, the nano silver wire had high uniformity and a high conductivity. Example 12 [0045] An ammonium hydroxide solution of silver oxide (with a silver oxide concentration of 5 mg/mL and an ammonium hydroxide concentration of 33%) was put into a syringe connected to a core pipe of a needle. A methanol solution of PVP and TBAP (with a PVP concentration of 100 mg/mL and a TBAP concentration of 30 mg/mL) was put into another syringe connected to a shell pipe of the needle. The silver precursor solution in the core pipe was controlled by a syringe pump to have a flow rate of 0.01 mL/hr, and the polymer solution in the shell pipe was controlled by another syringe pump to have a flow rate of 1 mL/hr. A nano line having a diameter of about 0.6 μm and a length of 10 cm was electrostatically spun. The nano line was annealed at 200° C. under the atmosphere for 20 minutes, and then washed by water to remove the polymer tube. As such, a nano silver wire with a diameter of about 375 nm was obtained. As known by comparison with Example 11, a nano silver wire having a larger diameter can be obtained through a higher silver oxide concentration. As known by comparison with Example 10, a nano silver wire having a smaller diameter can be obtained through a higher TBAP concentration. [0000] TABLE 3 Nano Nano Nano silver Silver oxide TBAP silver silver wire con- con- wire wire aspect centration centration diameter length ratio Example 9 1 mg/mL 10 mg/mL ~357 nm 10 cm 2.8 × 10 5 Example 10 5 mg/mL 10 mg/mL ~464 nm 10 cm 2.2 × 10 5 Example 11 1 mg/mL 30 mg/mL ~285 nm 10 cm 3.5 × 10 5 Example 12 5 mg/mL 30 mg/mL ~375 nm 10 cm 2.7 × 10 5 [0046] It will be apparent to those skilled in the art that various modifications and variations can be made to the disclosed methods and materials. It is intended that the specification and examples be considered as exemplary only, with a true scope of the disclosure being indicated by the following claims and their equivalents.

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CROSS-REFERENCE TO RELATED APPLICATION This application claims the benefit of U.S. Provisional Patent Application No. 60/231,638 filed Sep. 11, 2000. BACKGROUND OF THE INVENTION This invention relates to fingerprint processing. More particularly, this invention relates to the capture of fingerprints from generally inanimate objects. The invention is particularly useful in the science of forensics. For the past 100 years, law enforcement agencies have collected human fingerprints from crime scenes in order to identify the perpetrators of various felonious crimes from petty larcenies to murders. In the past, the fingerprints were discovered at the scene and crime scene technicians would apply powders to the prints, which are actually human skin oils that are deposited on the evidence. The skin oils would adsorb the powder and become whitish in color, which allowed for either photography or removal from the evidence with adhesive tape. From the crime scene, the latent prints would be taken to a lab, photographed, categorized, and then compared visually by skilled technicians to vast quantities of prints on file. This procedure was followed in order to locate a match, thereby identifying a suspect. Modern forensic science has improved upon this process immensely. Fingerprint identification is done now by using sophisticated computer programs run by main frame computers in such centers as the FBI fingerprint labs in Washington D.C. Manual inspection of card files is almost a thing of the past. The computers use scanning technology to read fingerprint evidence from prepared samples and automatically categorize and match the prints to corresponding prints stored in a database. One problem that needed to be overcome to enable the law enforcement agencies to implement this system was that the latent fingerprint itself is a very fragile object. A powdered fingerprint could be easily smeared which could render it useless for comparison to known prints. Also, fingerprints are generally very faint, which led to many prints not being found in the first place. Even with the adhesive tape method, fingerprint removal from the crime scene to the lab was tenuous at best. A method was needed to enable the forensic technicians to find all fingerprints, improve the contrast between the prints and the surrounding surfaces, harden the prints so that smearing is less likely and transport from site to site is possible. The answer was found to be a development process using fuming cyanoacrylate ester. Cyanoacrylate ester is a cyanide compound that has superior adhesive properties, especially for human tissue. It is commonly sold under trade names such as SuperGlue. As most people know, when cyanoacrylate ester is applied to two skin surfaces which are then brought into contact, the skin surfaces fuses and stick together. The result can range from merely annoying, if two fingers are fused, to extremely dangerous, if an eye membrane and skin are involved. The adhesive property of cyanoacrylate esters is so well known that medical researchers are investigating the possibility of using the compound to replace sutures in closing of wounds and incisions during operations. Forensic scientists used this property of fusing and hardening skin oils to their advantage by heating the liquid cyanoacrylate ester and causing a mist or vapor to be formed. This vapor deposits on the latent fingerprint oils, hardens them and turns them whitish in color. When dry, the print treated by vaporous cyanoacrylate ester is very resistant to smearing, fixed to the substrate and is easily seen against a darker background. In addition. if the entire piece of evidence, such as a plastic garbage bag, gun or knife is subjected to the fumes, all fingerprints which are on the evidence will be developed and will stand out visually, reducing the possibility of losing fingerprint evidence. After developing, fingerprint evidence is processed further, allowing scanning into a computer for comparison and identification, all by techniques that are now well-known to the art. This method has been utilized for many years with excellent results and is now the state of the art for fingerprint processing. However, some detriments are also inherent in this method. When the cyanoacrylate ester is heated, a white vapor or mist is formed. The particle size of the vapor is very small and is easily respirable. When inhaled, the small particles can migrate into the small pulmonary channels of the lungs and cause irritation or other lung reactions that are deleterious to lung tissue. As importantly, when cyanoacrylate ester is heated, the possibility of compound breakdown exists wherein hydrogen cyanide is formed and is present in the vapor. It is well known to health experts that hydrogen cyanide (HCN) is toxic and dangerous to human health. Inhaling this compound is to be avoided. Products have been developed to contain the vapors of cyanoacrylate ester and offer some degree of protection for the user. Generally, the design of these items is similar to laboratory fume hoods or glove boxes, wherein the evidence is placed, the sash or door closed, the liquid cyanoacrylate ester is fumed, misted, or vaporized and the fingerprints are processed. At the end of the deposition phase, the fumes are vented via a fan to an outside exhaust. By definition, this type of chamber is fixed in location, usually in a laboratory environment. Since solid connection to the ductwork is required, portability within the lab or from the lab is not possible. Also, all of the vapors are expelled to the atmosphere, increasing pollution levels emitted in the lab exhaust. If higher levels of HCN are present, a potential safety hazard is incurred since the HCN is traveling throughout the lab's ductwork. If the process is being carried out in the field, a portable enclosure, in some cases an inverted fish tank is used to contain the vapors. At the end of the fuming cycle, the chamber is simply lifted off and the vapors are allowed to dissipate in the atmosphere. Of course, a breeze or wind could blow the vapors back into the face of the technician or deposit the vapors on other surfaces such as car paint or such. All of these solutions, however expedient, are not fully safe, nor are they automated in any way. Technician training and experience is very critical to the fuming process, in that too much or to little cyanoacrylate ester fumes or processing time could destroy the fingerprints and therefore important case evidence. This user dependence is compounded by the realization that the fuming process is also temperature and humidity dependent, in that it is well known that best results are obtained at about 80% RH at 72 F. Control (or at least measurement) of these parameters would allow for more consistent processing. OBJECTS OF THE INVENTION An object of the present invention is to provide an improved apparatus and/or method for capturing a fingerprint from an object. A more particular object of the present invention is to provide such an apparatus and/or method which is portable. Another particular object of the present invention is to provide such an apparatus and/or method which has enhanced safety features. An additional object of the present invention is to provide such an apparatus or method which facilitates optimal deployment of a chemical fingerprint fixative agent such as cyanoacrylate ester. A further object of the present invention is to provide such an apparatus or method which is easy to use owing in part to automatic operation. These and other objects of the present invention will be apparent from the drawings and descriptions herein. SUMMARY OF THE INVENTION An embodiment of a fingerprint capture or processing apparatus comprises, in accordance with the present invention, a casing defining a sealable chamber, a first support in said chamber for holding a source of a chemical fingerprint fixative agent, a second support in said chamber for holding an article to be tested for fingerprints, a filtration system connected to said chamber for removing contaminants from air in said chamber, and an air circulation assembly operatively connected to said casing for circulating air from said chamber and through said filtration system. In accordance with another feature of the present invention, the fingerprint capture or processing apparatus further comprises a humidity control device connected to the air circulation assembly for modifying a humidity level in the chamber to a predetermined relative humidity. It is contemplated that the humidity control includes a humidity sensor or measurement device disposed in operative communication with the processing chamber. The humidity modification may be effectuated in part by an ultrasonic humidifier device. In accordance with an additional feature of the present invention, the air circulation assembly includes ductwork defining a first path for directing air from the chamber through the filtration system and ductwork defining a second path bypassing the filtration system for guiding air from the chamber. The second pathway is used, for example, to circulate air through the processing chamber during a humidity adjustment process prior to a delivery of a chemical fixative agent to the processing chamber. The air circulation assembly may include a first fan or blower for moving air along the first path and a second fan or blower for moving air along the second path. Pursuant to a further feature of the present invention, the air circulation assembly communicates with the fingerprint processing chamber near an upper end and a lower end thereof, whereby air from the chamber may be filtered or cleaned by the filtration system and subsequently returned to the chamber. A perforated plate may be suspended from sidewalls of the casing over the first support, thereby dividing the chamber into an upper compartment and a lower compartment. In that case, the air circulation assembly is connected to the casing at the lower compartment for blowing cleaned air into the lower compartment. Where the casing includes a door for enabling access to the chamber, the fingerprint capture or processing apparatus further comprises a contaminant sensor in operative communication with the chamber for monitoring quality of air in the chamber, and a lock mounted at least indirectly to the casing for locking the door. The lock is operatively connected to the contaminant sensor for enabling opening of the door only when the chamber is effectively void of contaminant particles. A heating element is disposed in the fingerprint processing chamber for heating the fingerprint fixative agent during a beginning phase of a fingerprint detection procedure. In accordance with additional features of the present invention, at least one timer is operatively connected to the air circulation assembly for determining air purge and recycle periods, while the casing includes at least one transparent panel, whereby an operator can monitor an extent of fingerprint fixation. A method for processing objects for fingerprints comprises, in accordance with the present invention, placing an article to be tested for fingerprints into a chamber, thereafter sealing the chamber, introducing a chemical fingerprint fixative agent into the sealed chamber, cleansing or filtering air in the chamber to remove particles of the chemical fingerprint fixative agent after fixing of fingerprints on the article by the chemical fingerprint fixative agent, preventing access to the chamber after the sealing thereof and prior to the removal of the particles of the chemical fingerprint fixative agent from the chamber, and enabling access to the chamber by an operator only after cleansing or filtering of air in the chamber to effectively remove particles of the chemical fingerprint fixative agent. A method in accordance with the present invention facilitates fingerprint capture while simultaneously protecting personnel from biologically dangerous or deleterious chemicals used in the fingerprint fixation process. The chemicals are filtered from the air of the chamber prior to the opening of the chamber after a fingerprint capture process. Access to the chamber is prevented during the fingerprint capture or fixation process, prior to removal of effectively all particles of the chemical fingerprint fixation agent. Where the placing of the article into the chamber includes opening a door to the chamber, the article is inserted through the opened door into the chamber, and the door is subsequently closed, while the sealing of the chamber includes locking the door to prevent an opening of the door prior to the cleansing or filtering of air in the chamber. The cleansing or filtering of air in the chamber includes circulating air from the chamber through a filtration system. Preferably, the cleansing or filtering of air in the chamber further includes returning air to the chamber after the circulating of the air through the filtration system. A fingerprint capture apparatus and method in accordance with the present invention facilitates the capture of fingerprints by a forensic scientist or technician in part by providing easy access to the processing chamber (where the access door is a front panel of the casing) and in part by providing safety features which protect the user from the cyanoacrylate ester vapors. In addition, a fingerprint capture apparatus and method in accordance with the present invention enables the measuring and/or control of internal temperature and humidity, thereby optimizing the generation and application of cyanoacrylate ester vapors. A fingerprint capture apparatus and method in accordance with the present invention is easily portable within or from a lab and ensures removal of all contaminants from the fingerprint capture or processing chamber before venting of the air from that chamber to the lab or atmosphere. Moreover, a fingerprint capture apparatus and method in accordance with the present invention may incorporate control logic to adjust and control the length of time of purge cycles, fuming cycles and cyanoacrylate ester vaporizer heater elements. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of a fingerprint capture or processing apparatus in accordance with the present invention. FIG. 2 is a schematic internal view of the fingerprint capture or processing apparatus of FIG. 1, showing selected functional components and an air circulation path. FIG. 3 is a block diagram, showing functional components of the apparatus of FIG. FIG. 4 is a front, top and right side perspective view of a modified fingerprint capture or processing apparatus in accordance with the present invention. FIG. 5 is a back, top and left side perspective view of the apparatus of FIG. 4 . In the drawings, the same reference numerals are used to designate similar structural elements, even though there may be differences in form between different embodiments. A slight modification of the form of a structural element is not believed to substantially affect the function of that element. DESCRIPTION OF THE PREFERRED EMBODIMENTS As illustrated in FIGS. 1 and 2, a fingerprint capture apparatus includes a casing 10 having transparent side walls 12 and one or more lockable access doors 14 together defining a sealable processing chamber 16 . Side walls 12 are solid or semi-solid panels which are preferably transparent but can alternatively be opaque or translucent. Each door 14 is preferably hinged to a side wall 12 of casing 10 . However, doors 14 may take the form of any obstruction capable of being opened to allow access to processing chamber 16 and capable of being sealingly closed to prevent the escape of chemical fumes. Casing 10 includes a solid bottom or base panel 18 fastened to side walls 12 . All seams created by the four bottom edges of side walls 12 and the contiguous outer edges of base panel 18 are sealed gas tight. A second base or horizontal support 20 is suspended from side walls 12 above the level of the bottom or base panel 18 by standoffs or hangers 20 of any type. Base panel or support 20 is perforated to allow airflow through it with minimal restriction. Base panel or support 20 is spaced above bottom or base panel 18 by a predetermined but variable distance. Although a cubic enclosure or processing chamber 16 is illustrated, any geometric shape (as well as size) may be employed without straying from the intent of the instant disclosure. The fingerprint capture apparatus of FIGS. 1 and 2 further includes a housing structure 22 disposed above casing 10 for enclosing a filtration system 24 , an air circulation fan or blower 26 of an air circulation assembly 28 , air circulation duct work 30 and control electronics 32 (see FIG. 3 ). The top edges of side walls 12 are sealed air tight against the lower side of housing structure 22 . It is within the level of skill in the art to attach housing structure 22 to casing 10 so that the casing may be easily removable from the housing structure, with the side walls 12 hinged to the bottom of the housing structure. In this manner, the fingerprint capture or processing apparatus may be taken apart and folded down for easy storage or transportability. As illustrated in FIG. 4, a source of atomized water particles 66 such as an ultrasonic humidifier may be attached to one of the side walls 12 of casing 10 via a duct 111 and a flange 112 . A circulatory fan 110 is disposed between the horizontal support 20 and base panel 18 . A line 113 drawn perpendicular to base panel 18 and colinear with the fan's central axis is preferably co-planar with an axis 114 of connecting flange 112 . Air circulation assembly 28 does not exhaust directly to the ambient atmosphere, exterior to casing 10 and housing structure 22 . Instead, air circulation assembly 28 includes a duct 34 of any shape attached to housing structure 22 and casing 10 so as to allow the cabinet air to be returned to a base or lower compartment 36 (below base panel or horizontal support 20 ) after removal of all toxic and noxious compounds by air filtration system 24 so that when a front door or portal 14 is opened, only cleaned air can escape. Fan or blower 26 provides sufficient motive energy to move the air through the apparatus by means known to the art. Air return duct 34 is attached to casing 10 at the lower compartment 36 via a flange arrangement disposed between the bottom or sealing base panel 18 of casing 10 and the suspended horizontal support 20 . In this manner, the air can be circulated along the path indicated by arrows 38 , from the lower compartment 36 of casing 10 , through an upper compartment 40 of processing chamber 16 , through filtration system 24 , and back to base or lower compartment 36 again. Air filtration system 24 comprises a fibrous prefilter 42 , which is sized to remove small particles by means of mechanical constriction or electrostatic attraction. These filters are commonly available through industrial supply sources. In addition, air filtration system 24 comprises activated carbon filter media 44 . In practice, air filtration system 24 may be a combination of a layer of standard activated carbon granules and a layer of carbon impregnated with chemicals which will adsorb and react with cyanide compounds. In this manner, one filter assembly may remove cyanoacrylate ester, odors and cyanide from the air. Alternatively, two (or more) separate filters may be employed. Of course, the filters must be installed and sealed using techniques known to the art so that air cannot bypass the filters. As illustrated in FIG. 3, control electronics 32 includes a humidity or moisture sensor 46 located inside plenum 103 , set to monitor the relative humidity levels inside processing chamber 16 and to provide an analog output proportional with the relative humidity values. The humidity sensor 46 is exposed to the relative humidity levels inside processing chamber 16 due to its location along air path 106 . In order to ensure that the relative humidity levels along path 106 are of close or equal values, circulatory fan 110 is operated in conjunction with humidifier 66 . More particularly, humidity sensor 46 is part of a humidity control (not separately designated) for ensuring that the humidity level in processing chamber 16 at the onset of a fingerprint capture operation is at a preselected relative humidity optimal for the generation of gaseous vapor from a liquid chemical fingerprint fixation agent (e.g., cyanoacrylate ester) deposited (in a tray) on a hot plate 48 in turn disposed in a support 50 in lower compartment 36 of processing chamber 16 . As further illustrated in FIG. 3, control electronics 32 includes an input or control panel 52 such as a keypad for setting a length of time for fuming cycles and air purge cycles. Control electronics 32 additionally includes a timer 54 for measuring out preset cycle periods. Air circulation assembly 28 operates for the preset periods to move air from processing chamber 16 through air filtration system 24 to remove chemical particles (e.g., cyanoacrylate ester and hydrogen cyanide) from the chamber air. Control electronics 32 further includes magnetic switches 116 for confirming a closed position for doors 14 and 107 . Control electronics 32 also includes a pressure switch 115 to monitor the pressure drop level across fan or blower 26 . This ensures that filter 24 is set so it cannot be bypassed by air moving along air path 38 . Input or control panel 52 is operatively connected to a control logic module 56 (optionally located in the housing structure 22 ) containing logic type controls or microprocessors which control the operation of the automatically functioning components illustrated in FIG. 3 . In particular, control logic module 56 is operatively connected to a motor 57 of fan or blower 26 , to humidity measurement sensor 46 , and to an automatic door lock 60 . Lock 60 is operatively connected to portal or door 14 for preventing access to processing chamber 16 after a sealing of door 14 and prior to an effectively complete removal, from the chamber, of particles of the chemical fingerprint fixative agent heated by hot plate or heater 48 . Control logic module 56 is operatively connected to lock 60 for enabling access to processing chamber 16 by an operator only after sufficient operation of air circulation assembly 28 to effectively cleanse or filter air in the chamber to remove particles of the chemical fingerprint fixative agent (e.g., cyanoacrylate ester). A chemical sensor 62 (FIG. 3) is disposed in operative communication with a plenum 117 (FIG. 2) for detecting the presence of particles of the chemical fingerprint fixation agent used. Sensor 62 is operatively connected to control logic module 56 for signaling, to that unit, breakthrough of the chemical fixation agent past the air filtration system 24 , so that module 56 allows lock 60 and subsequently door 14 to be opened only after a timed operation of blower 26 and in the absence of any output signals from chemical sensor 62 . This ensures that the air in chamber 16 has been cleaned to an acceptable contaminant content. Control logic module 56 of control electronics 32 is also connected to heater or hot plate 48 for energizing the hot plate during a fingerprint capture operation initiated by operator input via control panel 52 . Control logic module 56 turns the hot plate off at the completion of a timed cycle or in response to an operator triggered signal from control panel 52 . The operator can terminate the session upon visually detecting the presence of fingerprints on an article inserted into processing chamber 16 . Monitoring circuits and alarms (not illustrated) may be provided for tracking filter life. Also, safety circuits and devices such as line fuses, EMC line filters, and over temperature monitors and controls. As illustrated in FIG. 4, a fingerprint capture apparatus may include on a front side, an additional lockable door 107 which provides access to lower compartment 36 . Door 107 is preferably hinged to a front panel of casing 10 and effectuates a sealed engagement therewith. Door 107 may take the form of any obstruction capable of being opened to allow access to lower compartment 35 and capable of being sealingly closed to prevent the escape of chemical fumes. As depicted in FIG. 5, a fingerprint capture or processing apparatus as described herein may be provided with an ancillary air circulation system 101 which does not exhaust directly to the ambient atmosphere. Instead, air circulation system 101 includes a one-way valve 102 attached to housing structure 22 and casing 10 so as to allow the cabinet air to be moved from casing 10 into a plenum 103 above the air filtration system 24 and blower 26 , and then back to the base or lower compartment 36 (below base panel or horizontal support 20 ). Airflow generated by a fan or blower 104 ensures that filtration system 24 is bypassed while the air circulation system 101 is used. Fan or blower 104 provides sufficient motive energy to move air through the apparatus by means known to the art. Air return or air-flow guide ducts 108 and 109 are attached to casing 10 and housing structure 22 via flange-elbows 105 . In this manner, air can be circulated along a path indicated by arrows 106 , from the lower compartment 36 of casing 10 , through upper compartment 40 of processing chamber 16 , along guide duct 108 , through plenum 103 , along duct 109 , and back to base or lower compartment 36 again. It is to be noted that air return duct 109 (FIG. 5) may be the same as air return-duct 34 (FIG. 2 ), so that in both air circulation assembly 28 and air circulation system 101 , air is returned to the lower compartment 36 of processing chamber 16 by a single duct. The apparatus of FIGS. 1-5 is generally used in a fingerprint capture process as follows: The apparatus is connected to a specified power source, such as a 115VAC 60 Hz electric socket. A main power switch (e.g., on control panel 52 ) is turned on. Control electronics 32 and particularly control logic 56 generally executes a start routine which allows the stabilization of circuits and the monitoring of filter conditions and ambient air conditions. A ready message (e.g., on control panel 52 ) signifies that the apparatus is in a condition for process commencement. The user will place an article of forensic evidence into chamber 16 by either suspending the article from an internal hanger rod 64 or on a stand (not shown) disposed on horizontal support 20 . Generally, the article of evidence will be arranged such that all surfaces of the article will be exposed to the vapors of the chemical fingerprint fixation agent (e.g., cyanoacrylate ester), as opposed to laying the article on support 20 . In addition, the user will place an aluminum tray (not shown) containing a small amount of liquid cyanoacrylate ester on the exposed hot plate 48 which is initially cool. At this juncture doors 14 and 107 are closed and secured. The user engages the system by pressing a Start Cycle button (not shown) on control panel 52 . The door lock 60 is normally closed and in locked condition. Control logic module 56 then activates recirculatory blower 104 and circulating fan 110 in order to establish current ambient conditions. Sensor 46 measures the relative humidity of the air in processing chamber 16 and communicates the measurement to control logic module 56 . Module 56 then adjusts the humidity in chamber 16 to a relative humidity level (preset, for example, via control panel 52 ) by engaging and disengaging an ultrasonic humidifier 66 , recirculatory blower 104 and circulating fan 110 . If for some reason the humidity level is not reached, an alarm will sound and the system will abort, preventing damage to the evidence. After the preset humidity level is reached, as measured by sensor 46 , control logic module 56 disengages recirculatory blower 104 , circulatory fan 110 and humidifier 66 . At that time, control logic module 56 will energize hot plate 48 to preset levels and actuate circulatory fan 110 . Circulatory fan 110 ensures homogenous conditions within the processing chamber 16 . At about 80 to 90 degrees C., the cyanoacrylate ester will begin to vaporize. This vaporization will continue as a user set timed cycle and under user observation. Additional cyanoacrylate ester could be added as needed via the hot plate access door 107 . This ensures the continuation of an already initiated cycle while minimizing the operator's exposure to the cyanoacrylate fumes. The open condition of door 107 is picked up via the magnetic switch 116 . As a result an audio-visual alarm is triggered. If the technician feels that the fingerprints have reached proper stage of development prior to the completion of the timed cycle, then he or she will press a Purge Cycle switch (not separately shown) on control panel 52 . This action will allow the control logic 66 to turn off power to hot plate 48 , engage air fan or blower 26 and begin the measurement of a purge cycle by timer 54 . During this period, the air in the processing chamber 16 will be recycled through filtration system 24 to cleanse the air of the vapors and chemicals. A purge cycle will be triggered automatically if the magnetic switch 116 senses an open condition of access door 14 . Sensor 62 monitors the chemical content of the filtered air and provides an analog output to the control logic 56 . An analog signal greater than a preset threshold indicates that chemicals are still present in the gas stream after purging and triggers an alarm (not illustrated). Hot plate 48 cools down and the vapor emissions will cease. After a preset period, the air fan or blower 26 will disengage, and the door lock 60 can be disengaged by pressing the Unlock button (not shown) located on control panel 52 . A Purge Cycle Complete message will be displayed on control panel 52 . The user may then open the door 14 and remove the evidence. At this point, another tray of cyanoacrylate ester may be prepared and the sequence started again with another piece of evidence. When all of the devices, controls and apparatus are assembled in the manner described herein, a safe, secure and automated fingerprint development system can be constructed and utilized. Although the invention has been described in terms of particular embodiments and applications, one of ordinary skill in the art, in light of this teaching, can generate additional embodiments and modifications without departing from the spirit of or exceeding the scope of the claimed invention. Accordingly, it is to be understood that the drawings and descriptions herein are proffered by way of example to facilitate comprehension of the invention and should not be construed to limit the scope thereof.

4y

This application is a continuation-in-part of Ser. No. 07/806,183, filed Dec. 13, 1991, now patented as U.S. Pat. No. 5,286,626, issued Feb. 15, 1994. FIELD OF THE INVENTION The present invention relates to a process for the direct determination of low density lipoprotein in body fluids. More specifically, the present invention relates to a process and apparatus for determination of low density lipoprotein by selectively precipitating low density lipoprotein from a sample, providing enzymes which selectively consume the high density lipoprotein, and then resolubilizing the low density fraction and determining this fraction enzymatically. BACKGROUND OF THE INVENTION Lipoproteins are complex particles consisting of protein and lipid which are found in the circulatory system. One of the functions of lipoproteins is to carry water-insoluble substances such as cholesterol and cholesterol esters for eventual cellular use. While all cells require cholesterol for growth, excess accumulation of cholesterol by cells is known to lead to certain diseases, including atherosclerosis. It is known that the amount of total serum cholesterol can be correlated with the incidence of atherosclerosis. However, there are a variety of classes of lipoproteins in serum which can be classified by their density. These classes include very low density lipoproteins (VLDL), low density lipoproteins (LDL) and high density lipoproteins (HDL). All of these classes of lipoproteins contain varying amounts of cholesterol, and a total serum cholesterol determination is a complex average of the amount that each lipoprotein-class contributes to the total lipoprotein population of the serum. It has long been suspected that some lipoprotein classes are more closely associated than other lipoprotein classes with the progression of heart disease, including atherosclerosis. In fact more recent studies have implicated LDL as the class of lipoproteins responsible for the accumulation of cholesterol in cells, whereas HDL has been shown to be important in the removal of excess cholesterol from cells. Additionally the correlation of atherosclerosis and the levels of LDL cholesterol is much higher than a similar correlation between atherosclerosis and total serum cholesterol levels. Conversely, there appears to be a negative correlation between atherosclerosis and HDL cholesterol levels. Despite the desirability of differentiating LDL cholesterol levels in blood plasma from those of other soluble cholesterols, a technique suitable for use in clinical laboratories has not heretofore existed. One method which has been suggested relies upon the interaction of heparin in the presence of calcium to precipitate both LDL and VLDL, cf. Bursterin et al., Adv. Lipid. Res. 11:67 (1973). To separate the LDL and VLDL fractions, ultracentrifugation techniques, which are time consuming and expensive, may be used. Ultracentrifugation, to separate the lipoproteins solely on the basis of their density, requires special equipment and long processing time. Electrophoretic separation also requires special equipment and long processing times. A variety of precipitation methods have been used which depend upon the use of polyanions and divalent cations, Okabe, Xth Int. Cong. of Clin. Chem., Mexico (1978); Genzyme Diagnostic, Cambridge, Mass., LDL cholesterol precipitation reagent package insert. Other precipitation methods use polymers, as shown in U.S. Pat. No. 4,474,898 and U.S. Pat. No. 4,647,280; or lectin, as disclosed in U.S. Pat. No. 4,126,416. Kerscher et al., in U.S. Pat. No. 4,746,605, teach that VLDL and HDL can be precipitated by HDL antibodies with polyanions and divalent cations. However, the amount of antibodies required with this method is too expensive for routine use. Other methods for determining the amount of lipoprotein fractions in samples are known, but these methods are not suitable for use in a dry-chemistry device which can be used for simple and rapid determination of lipoproteins. For example, Pascal, in U.S. Pat. No. 4,366,244, discloses that lipoprotein fractions can be separated by using a lectin to separate the LDL and VLDL fractions, and then measuring the amount of cholesterol in the precipitate and in the remaining solution. This method requires centrifugation of the precipitate, and measurement of both the precipitate and the remaining solution. Ziegenhorn et al., in U.S. Pat. No. 4,486,531, disclose a turbidimetric process for detection of beta-lipoproteins (LDL) in body fluids by precipitation with polyanions and divalent cations. The LDL then can be detected directly by a turbidimetric determination. When LDL is precipitated with polyanions such as dextran sulfate and divalent cations such as magnesium, the precipitate redissolves if one tries to selectively convert the cholesterol in the supernatant by an enzymatic assay which requires the presence of surfactants. Moreover, cholesterol esterase and cholesterol oxidase present in the system hydrolyze the LDL. Another method for determining LDL is calculation by the Friedewald Formula, as disclosed in Friedewald et al., Clin. Chem. 18: 499-502 (1972). In this method, LDL is estimated by the total cholesterol, HDL, and triglyceride contents of the sample. This method requires multiple assays, and is not accurate for samples containing high levels of triglycerides. Consequently, there is a need for a simple procedure or device for the determination of LDL lipoprotein accurately. SUMMARY OF THE INVENTION It is an object of the present invention to overcome the aforementioned deficiencies in the background art. The present invention provides a simple method and apparatus for the determination of LDL. An important feature of this invention is the use of nucleating particles to facilitate precipitation of LDL in stable form. According to the present invention, a precipitating reagent for LDL is added to a fluid sample. The LDL present in the sample rapidly precipitates, and enzymes are added to react with HDL and VLDL in the sample. The LDL is then redissolved, and the LDL is detected by any conventional means. LDL precipitate normally dissolves quickly in the presence of surfactants such as sodium cholate, and cholesterol esterase usually rapidly hydrolyzes any cholesterol esters in lipoproteins in the presence of suitable surfactants. However, the presence of sufficient small particles to provide nucleating agents for clusters of LDL stabilizes the clusters against the effect both of surfactants and of cholesterol esterase. Alternatively, the VLDL can be precipitated first, and then the LDL is precipitated with the specific precipitating reagents and nucleating particles of the present invention. Enzymes are added to react with HDL in the sample, and the LDL is redissolved and detected according to conventional detection means for LDL. Enzymatic means for detecting LDL are preferred. The nucleating particles preferably range in size from about 0.1 to about 100 microns, and may be either mixed with the polyanionic compound or the polyanionic compound may be immobilized thereon. The preferred particles are porous iron oxide. The advantage of the method of the present invention is that LDL can be effectively separated from other components of whole blood to provide a reliable, quantitative assay of LDL. Additionally, this method proceeds very quickly (usually in less than 120 seconds), so it is particularly well suited for use in disposable assay devices as described in this specification. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a side view of a direct LDL measurement device according to the present invention. FIG. 2 is a side view of another direct LDL measurement device according to the present invention. DETAILED DESCRIPTION OF THE INVENTION According to the present invention, a fluid sample, such as whole blood, is treated with a precipitating reagent to form clusters of LDL. This precipitating reagent preferably comprises a mixture of large polyanions and divalent cations, and the precipitation reaction is mediated by nucleating particles. The clusters of LDL so formed are surprisingly stable in the presence of cholesterol enzymes. Cholesterol enzymes, such as cholesterol oxidase and cholesterol esterase, are then added to the sample. At this point the HDL and VLDL lipoproteins in the liquid phase are consumed, while the solid phase LDL clusters remain intact. The LDL is then redissolved by a redissolution agent, and is then analyzed by any conventional means. One convenient method of analyzing the LDL is by enzymatic analysis to form hydrogen peroxide, which is then assayed colorimetrically. The greater the specificity of the precipitating agent for LDL, the more useful it is in the present invention. However, some precipitation of HDL and/or VLDL may be tolerable, depending on the diagnostic context. Preferably, the lipoprotein precipitates are at least 90% LDL. Alternatively, instead of precipitating LDL and then removing the HDL and VLDL, the VLDL can be selectively precipitated first. After the VLDL has been precipitated from the sample, clusters of LDL are then formed by adding a polyanionic compound, a salt of a divalent metal and a nucleating agent to the sample. Appropriate enzymes are then added to consume HDL, and the LDL clusters are treated with a redissolution agent to resolubilize the LDL for determination by conventional means. The polyanions that can be used for forming the LDL clusters can be any polyanions which precipitate lipoproteins which do not interfere with subsequent assays for LDL. Among the polyanions that can be used are dextran sulfate, heparin, phosphotungstic acid, and polyvinyl sulfate. The dextran sulfate can be high molecular (i.e., molecular weight of from 5×104 to 2×10 6 ) or short-chained (molecular weight of from 5000 to 50,000). The preferred concentration ranges of the polyanions in the reaction mixture are from about 0.1 to about 8 grams/liter in the case of high molecular weight dextran sulfate, from about 1 to about 15 grams/liter in the case of short-chained dextran sulfate and heparin, from about 0.2 to about 5 grams/liter in the case of polyvinyl sulfate, and from about 0.3 to about 6 grams/liter in the case of phosphotungstic acid. The polyvinyl sulfate is a polymer derived from polyvinyl alcohol, of which polymer at least 20% of the vinyl alcohol groups are sulfated. The molecular weight of the polyvinyl alcohol is not critical as long as it can be crosslinked. This is generally the case at a molecular weight of about 5000 or higher. Very favorable results can be obtained at molecular weights in the range of 10,000 to 150,000 or more. For best results, at least 50% of the vinyl groups are sulfated. Optimum results are obtained wherein at least about 65% of the vinyl alcohol groups are sulfated. Sulfation of the polyvinyl alcohol is preferably carried out using a reaction product of sulfur trioxide or cholorsulfonic acid and a Lewis base. Particularly suitable is the addition product of pyridine to sulfur trioxide. The sulfation reaction is preferably carried out in dimethyl formamide or formamide at a temperature of between 60° and 110° C. The polyvinyl alcohol may be crosslinked before or after sulfation, and the crosslinking may be effected either chemically or physically. The divalent cations that can be used in the system of the present invention include the II-A and II-B cations, particularly calcium, magnesium and manganese. As with polyvalent anions, the divalent cations may be of any species which has the desired precipitating effect and which does not interfere with the subsequent LDL determinations. These cations can be added in the form of a soluble salt such as a chloride salt. The concentration of the divalent metal ions to be added is preferably from about 10 to about 250 mMole/liter in the reaction mixture. A conventional buffer can be used to buffer in a pH range of from about 6.5 to about 8.5, such as MES (morpholino ethane sulfonic acid), triethanolamine, MOPS (morpholino propane sulfonic acid) or Tris buffer. The invention is not limited to the use of any particular precipitating agent. Once the LDL fraction has been separated from the other components in the sample, conventional methods of analysis can be used for the LDL determination. The LDL determination can, for example, take place by saponification with alcoholic potassium hydroxide solution and chemical determination according to Liebermann-Burchard. However, it is preferred to use an enzymetic determination using cholesterol oxidase (CO) and a cholesterol ester-splitting enzyme or enzyme system, such as cholesterol esterase (CE). In the case of the use of cholesterol oxidase, the determinations can be based upon the amount of oxygen consumed, the amount of cholest-4-one-3-one formed, or the amount of hydrogen peroxide formed using conventional methods for this purpose. Since the determination of bound cholesterol is well known, there is no need to describe it it detail. The invention is not limited to any method of determining a precipitated LDL. The particles that can be used as nucleating agents for forming the LDL clusters can be any nucleating particles that do not interfere with the subsequent assay for LDL. For example, iron oxide, chromium dioxide, stainless steel, silicon dioxide, glass, methyl methacrylate particles, and the like can all be used. These nucleating agents must be insoluble in the liquids used in the assay, i.e., generally insoluble in water. The particle may be organic or inorganic, and, if inorganic, may be amorphous or crystalline. The inorganic salts may be, but are not limited to, metal salts, such as salts of iron or chromium. Among inorganic salts, metal or otherwise, oxide (including dioxide) salts are preferred, as they are unlikely to interfere with an oxidative reaction. The particle size is preferably between about 0.5 and 200 microns, more preferably 1-10 microns. However, to obtain a precipitate of large agglomerates (e.g., larger than about 100 microns) in less than 60 seconds, which is particularly useful with the devices disclosed herein, porous iron oxide with an average diameter of from about 1 to about 10 microns (Reference Diagnostics, Arlington, Mass.), is most preferred. The nucleating agents can be added in with a mixture of the polyanionic compound and the divalent metal. Alternatively, the nucleating agents can be coated with the polyanionic compound or various compounds and added along with the divalent metal to the fluid sample. Preferably, the nucleating agent precipitates more than 50%, more preferably, at least 75%, still more preferably at least 95% of the LDL. Preferably, substantial precipitation occurs in less than 120 seconds, more preferably less than 60 seconds, still more preferably less than 30 seconds. It is desirable that a good solid pellet be formed and that the pellet be readily redisolved by the redissolving agent. Preferably, the nucleating agent stabilizes the precipitate so that less than 20%, more preferably less than 10%, is redissolved by cholesterol esterase and/or cholesterol oxidase. The redissolution agent, for redissolving the LDL that was found to be most effective was a mixture of EDTA and sodium chloride, however, the invention is not limited to this agent. Other chaotropic agents and/or surfactants known in the art may be used. When a combination of EDTA and sodium chloride is used, a solution of 2.5-6.5% sodium chloride and 0.05-0.10% EDTA is especially preferred. Other redissolution agents, such as from about 75-100 units protease per test and from 50 to 200 mM magnesium chloride per test can also be used. The redissolution agents change the ionic strength of the sample, breaking up the lipoprotein clusters in less than thirty seconds. The redissolution agent may be provided in a liquid or solid (but solubilizable) phase. The process of the present invention is particularly well suited for use in devices colorimetrically which register the amount or presence of LDL in a sample. Because the reaction of the present invention proceeds quite rapidly, generally within about 120 seconds, a reading can be obtained within a short time, so that the test can be performed in, for example, a physician's office or a health clinic. The following exemplify two types of devices which can be used with the process of the present invention. Of course, these examples are for illustrative purposes only, and not for limitation. Referring to FIG. 1, one embodiment of a device according to the present invention is shown at 10. A fluid sample is introduced to the device at a sample initiation area 20, and red blood cells are trapped in layer 11. Plasma then enters an LDL precipitation zone, layer 13. A particle enhanced LDL precipitation reagent 21 in zone 13 causes the LDL to precipitate in large clusters 22 in less than 60 seconds. The enzymes cholesterol esterase (CE) and cholesterol oxidase (CO), together with the surfactants deposited in zone 13, react with the HDL and VLDL to produce hydrogen peroxide. Surprisingly, the particle enhanced LDL precipitate 22 does not dissolve and does not react with the cholesterol enzymes, so that only the HDL and the VLDL react with the cholesterol enzymes, and the hydrogen peroxide generated thereby is consumed by endogenous catalase in less than ten minutes. Zone 14 is a thin sucrose coating and is designed to dissolve in less than ten minutes. An alternative dissolvable coating may also be used. An LDL redissolution zone, zone 15, contains dried hydroxylamine (HA), or an alternative catalase inhibitor, and LDL redissolution agents. When zone 14 is dissolved, both the hydroxylamine and the LDL redissolution agents are mixed with the contents of the LDL precipitating zone 13, where the catalase is inhibited by hydroxylamine and the LDL clusters are then dissolved by the action of the LDL redissolution agents. The re-dissolved LDL then reacts with cholesterol oxidase and cholesterol esterase, or other agents which catalyze hydrogen peroxide-generating reactions when LDL is available as a substrate, generating hydrogen peroxide which flows through a timing barrier 17 into the measurement zone 16 on the device. The length of the color bar developed in the measurement zone is proportional to the concentration of the LDL in the whole blood sample. More specifically, during the first ten minutes, the reactions in zone 13 are as follows: ##STR1## During this stage, the LDL ppt is not oxidized by air, despite the presence of CO and CE. During the next five minutes, the reactions in layer 13 are as follows: ##STR2## The hydroxylamine inhibits catalase-mediated enzymolysis of the H 2 O 2 . The device of the present invention can be used with a different enzyme system, as shown in FIG. 2. In FIG. 2, whole blood is introduced into the device 10 at 20, the top of layer 11. Red blood cells are trapped in zone 11, and plasma enters zone 13. A particle enhanced LDL precipitation reagent 38 in zone 13 causes LDL to precipitate in large clusters 22 in less than 60 seconds. In addition, zone 13 is buffered to about pH 9, and contains cholesterol esterase, cholesterol oxidase, cholesterol dehydrogenase (CDH), redissolution agents, NAD, surfactants and cation exchange resins. HDL in the plasma reacts with cholesterol esterase, cholesterol dehydrogenase and NAPD to produce NAPDH, while the LDL precipitate remainsunaffected. The pH in zone 13 drops with time because of the cation exchange resins which was placed inside this zone. Additionally, as the pH falls from 9.0 to 7.0, the cholesterol dehydrogenase becomes inactivated, while the cholesterol oxidase and protease become activated. The LDL precipitate is then dissolved by the protease, and cholesterol esterase and cholesterol oxidase react with LDL to generate hydrogen peroxide. The hydrogen peroxide so generated flows through the timing barrier 17 into the measurement zone 16. The length of the color bar developed in the measurement zone is proportional to the concentration of the LDL in the whole blood sample. Of course, it will be appreciated that the device specifically disclosed herein for use in assaying for low density lipoprotein are not the only devices in which the system for assaying for low density lipoprotein can be used. The system of the present invention can be used with any suitable device which provides a means for forming and trapping clusters of LDL which can be separated from HDL for analysis. EXAMPLE 1 A specific precipitation reagent for an undiluted plasma sample can be optimized by varying the concentration of magnesium chloride in the presence of 10 gram/L dextran sulfate (MW 50,000). As shown in Table 1, at 75 mM magnesium chloride concentration, only LDL precipitated out of the plasma, while HDL and VLDL remained in the plasma. Table 1 shows the concentration of cholesterol in plasma after precipitation and slow-speed centrifugation. __________________________________________________________________________500 mM 250 mM 125 mM 75 mM 50 mM 25 mM 10 mM__________________________________________________________________________VLDL 1.0 1.0 3.5 43.5 43.0 43.0 42.5LDL 1.0 0 1.0 0.5 3.0 148.0 153.5HDL 40.0 40.1 38.9 40.4 40.0 41.0 40.3__________________________________________________________________________ It can be discerned from the above that the optimum amount of magnesium chloride for forming a precipitate of LDL ranges from about 75 mM to about 500 mM. In this case, the LDL is precipitated preferentially from the VLDL and HDL. However, as shown in Example 2, the LDL precipitates formed are not stable in the presence of cholesterol enzymes such as cholesterol esterase and cholesterol oxidase, which enzymes are used to consume the HDL and VLDL from the sample so that these latter lipoproteins do not interfere with the LDL assay. EXAMPLE 2 Samples of 500 μL plasma with known assayed values of VLDL, HDL and LDL were treated with an LDL precipitating reagent with and without nucleating agents (40 mg porous iron oxide particles/mL solution) for one minute. The nucleating agent of choice was porous iron oxide, with average diameters ranging from 1 to 10 microns. After the precipitates were formed, an enzyme reagent containing 4 mg of sodium cholate and 30 units of cholesterol esterase was added to each sample. After three minutes of incubation, the precipitates were spun down at 3000 RPM and the supernatants were assayed for cholesterol values. The data in Table 2 show that the LDL precipitate formed with the nuclei remained insoluble in the presence of surfactant and cholesterol esterase, unlike clusters formed in Example 1 in the absence of nucleating particles. ______________________________________ LDL + % HDL + VLDL ENZYME DISSOLUTION______________________________________LDL PPT. 65 110 100LDL PPT. W/ 64 7 6NUCLEI______________________________________ Not all small particles tested exhibited similar effects for precipitating LDL. Particles such as silica and powdered glass worked well to enhance the size of the precipitates, but they did not speed up the formation of the precipitates significantly. By using particles of porous iron oxide, the preferred nucleating agent, large precipitates of LDL clusters form in less than 60 seconds in samples of plasma. Other particles were tried as nucleating agents, as described in the above example, with the results shown below: ______________________________________CHARACTERISTICS OF NUCLEATING AGENTPARTICLES FOR LIPOPROTEIN PRECIPITATIONENHANCEMENT CompletenessType of Pellet Ease of of precip-Particle Size formation redissolution itation______________________________________Iron oxides 0.6-10 good Yes 95-100% μm solid pelletIron powder 100 μm solid No 45-80% pelletChromium 0.5-20 solid Yes 80-85%dioxide μm pelletTitanium irreg- solid No 70-80%dioxide ular pelletSilica gel 4-20 μm poor No 50-94%* pelletSand 200-400 poor No 50-96%* μm pelletActivated 38-150 good No 75-85%charcoal μm pelletCellulose 6 μm poor No 60-80% pelletKaolin 0.1-4 μm poor No 75-79% pellet______________________________________ *Most runs were 50%-60%. EXAMPLE 3 In order to determine the presence and/or amount of LDL in a sample, the clusters formed must be destroyed and the LDL must be redissolved in the solution. Redissolution agents are used to redissolve the LDL. In this example, the LDL precipitate obtained in Example 2 was redissolved using redissolution agents. The most effective formulation for redissolving the LDL precipitate comprised a mixture of EDTA and sodium chloride. In one embodiment, for about 400 μL of samples, the final amount of sodium chloride in the sample is from about 2.5-6.5%, and the amount of EDTA is from about 0.05-0.12%. As shown in Table 3, LDL precipitates formed by the nucleated precipitating agents dissolved in less than 30 seconds after the redissolution agents were introduced, and the recovery of lipoprotein in the solution was close to 100%. Preferably, recovery is at least 90%, more preferably at least 95%. ______________________________________LDL IN SAMPLE 197 mg/dLLDL in supernatant after ppt. 2 mg/dLLDL after re-dissolution of 186 mg/dL (95%precipitates recovery)______________________________________ The foregoing description of the specific embodiments will so fully reveal the general nature of the invention that others can, by applying current knowledge, readily modify and/or adapt for various applications such specific embodiments without departing from the generic concept. Therefore, such adaptations and modifications are intended to be comprehended within the meaning and range of equivalents of the disclosed embodiments. It is to be understood that the phraseology or terminology herein is for the purpose of description and not of limitation. FIGURE LEGEND 10 assay device 11 layer for trapping red blood cells 13 LDL precipitation zone 14 zone with sucrose coating 15 Hydroxylamine and LDL redissolution agents 16 measurement zone 17 timing barrier 20 sample initiation area 21 particle enhanced LDL precipitation reagent 22 clusters of LDL 38 LDL precipitation reagent

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This application is a continuation of application Ser. No. 08/510,018 filed on Aug. 1, 1995, now abandoned. This invention relates to a blow molding apparatus. BACKGROUND AND SUMMARY OF THE INVENTION In blow molding machines of the wheel type, a wheel supports a plurality of circumferentially spaced sets of molds and is generally rotated about a horizontal axis. Plastic tubing is continuously extruded downwardly between the open mold sections and then the molds are closed as they move about an annular path and the portion of the tubing within the molds is blown within the confines of the mold to provide a hollow article which may be a container. When formed in dies, hollow plastic articles such as containers or bottles usually have flash in at least one of the shoulder, neck and finish areas. The finish also has material which must be removed to provide an end face for sealing engagement with a closure or cap engageable with the neck of the article. The present invention is directed to the problem of receiving containers or bottles from the plastic mold machine and delivering them to the trimming apparatus. In prior systems, the containers fall when the molds are open, bounce, turn-over and require orientation for delivery to the trimming apparatus. Among the objectives of the present invention are to provide a method and apparatus for removing containers from the molding machine and maintaining orientation of the container with respect to a delivery conveyor both with respect to the longitudinal axis of the container and the circumferential orientation of the container; which method and apparatus provides for uniform acceleration of the containers to delivery speed to the trimming apparatus without loss of such orientation. In accordance with the invention, the containers are delivered from a molding machine in the customary fashion wherein the molding machine has molds traveling in a circular path and are ejected, free-falling in the usual manner. Further, in accordance with the invention, a moving vacuum cup conveyor belt is provided which is constructed and arranged to grab the body of the container as it comes into contact with the cups, maintaining the orientation of the container as the container is accelerated to line speed of the conveyor. The conveyor delivers the containers to the trimming apparatus through a belt conveyor which is in timing relation to the vacuum cup conveyor. In a preferred form, the flash end of the container is supported by a flat belt operating at the same speed as the vacuum cup belt. DESCRIPTION OF THE DRAWINGS FIG. 1 is a front elevational view of a blow molding apparatus, parts being broken away. FIG. 2 is a fragmentary perspective view of a blow molding machine embodying the invention. FIG. 3 is a part sectional fragmentary elevational view taken longitudinally through the vacuum cup take out conveyor. FIG. 4 is a plan view of the conveyor shown in FIGS. 2 and 3. FIG. 5 is a fragmentary sectional view on an enlarged scale taken along the line 5--5 in FIG. 3. FIG. 6 is a sectional view taken along the line 6--6 in FIG. 4. FIG. 7 is a side elevational view of the vacuum cup take out conveyor and delivery conveyor. DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to FIGS. 1 and 2 in one type of plastic blow molding machine shown in U.S. Pat. No. 4,549,865, there is disclosed the blow molding apparatus for embodying the invention that comprises a frame 20 in which a shaft 21 is mounted for rotation about horizontal axis by spaced bearings in cantilever fashion. A wheel plate 22 is mounted on the shaft 21 for rotation with the shaft 21 and supports a plurality of circumferentially spaced slide assemblies 23. A hub 25 is also mounted on the shaft and has a plurality of circumferentially spaced mold supporting surfaces 26 corresponding in number to the number of slide assemblies 23. Each slide assembly 23 comprises mold section mounting means for supporting a section or part 27 of mold and the corresponding surface 26 of the hub 25 supports the second section 28 of a mold. Each slide assembly 23 is adapted to move the mold section 27 toward and away from the other mold section 28 to close about a plasticized parison emanating from an extruder head 29 so that the parison can be blown to the shape of the mold cavity defined by the mold sections 27, 28 as the wheel rotates. The parison is provided from the head 29 of an extruder in the two o'clock position as shown in FIG. 1. Wheel plate 22 is rotated by a gear 30 driven by a motor 31 and meshing with a gear 32 on the periphery of the wheel plate 22. Each slide assembly 23 includes a cam follower 33 which engages a fixed arcuate cam 34 on the frame 20 to move mold section 27 toward and away from mold section 28. A second cam follower 35 on each slide assembly 23 engages a second fixed cam 36 on frame 20 to hold the mold sections 27, 28 in closed and clamped position. Second cam 36 extends generally from the three o'clock position to just beyond the nine o'clock position as viewed in FIG. 1. The specific structure of each slide assembly 23 is disclosed and claimed in U.S. Pat. No. 4,648,831, which is incorporated herein by reference. An air valve assembly 42 is provided on each slide assembly 23 and is actuated by an actuator 43 along the path of the molds that functions to turn the blow air on for blowing the article and another actuator 44 is provided along the path to function to turn the air valve assembly 42 off, thereby cutting off the flow of blow air to the blowing apparatus. Each valve assembly 42 includes an on-off valve 45 that functions to control the flow of blow air to a valve block 46 and, in turn, through lines 47 to a blow pin (not shown) which functions to provide blow air for blowing the hollow article when the molds are closed, in a manner well known in the art. The valve assemblies 42 and actuator assemblies 43, 44 are disclosed and claimed in U.S. Pat. No. 4,523,904, which is incorporated herein by reference. In operation, the plastic material is continuously extruded in tubular form from the head 29 of the extruder and flows downwardly between the mold sections 27, 28. As the wheel plate continues to rotate, the mold sections 27, 28 are brought together for pinching the plastic material, and then air is supplied to the interior of the tubular parison to blow the article in a manner well know in the art. As the article reaches the position when the blow mold is open (12 o'clock position as viewed in FIG. 1), a fixed actuator 49 contacts an ejector on each mold section 28 to eject the articles onto a conveyor. In accordance with the invention, a vacuum cup conveyor system 60 is positioned to extend between the molds, when the molds are open, and receive the falling containers which have been molded, and grab the containers and move them in an oriented fashion to a delivery conveyor 62 (FIG. 4) to the trimming apparatus which may be of the type shown in U.S. Pat. No. 4,614,018, incorporated herein by reference. Conveyor 62 is also of the endless belt type (FIGS. 3 and 4) and, as best seen by the conveyor framework illustrated in FIG. 7, delivery conveyor 62 is adjustable angularly with respect to vacuum conveyor 60. Each container C includes a body portion B and a moil portion M (FIG. 4). Referring to FIG. 2 and also to FIGS. 3-7, the vacuum cup conveyor 60 comprises an endless belt 64 which supports a plurality of hollow stem vacuum cups 66 (FIG. 5) each of which has a diameter which is substantially less than the diameter of the body portion B of the container C. As shown in FIG. 5, the belt 64 is trained over pulleys 68, 70 and is supported between the pulleys by a plenum 72 that has an upper wall with openings 74 communicating with associated plenum troughs that in turn communicate with openings in the belt provided by the hollow stems of cups 66, the troughs extending below the travel path of each vacuum cup 66. As further shown in FIG. 5, the plenum 72 is positioned so that the lower reach of the belt 64 is below the plenum 72. Vacuum is supplied to the plenum 72 such that the portion of the belt passing over the plenum is supplied with vacuum. Preferably, an endless belt 76 (FIGS. 2 and 3) is provided for supporting the generally planar moil M of each container as the container accelerates and is moved toward the trimming apparatus. The vacuum cup conveyor 64 is driven in timed relationship with an endless belt delivery conveyor 80 through a timing belt 82 and associated pulleys 84, 86, (FIGS. 3 and 4) driven by motors D. In (FIG. 7) similar fashion the moil belt 76 is driven in timed relationship. The size and spacing of the vacuum cups is selected such that at least one and preferably two or more vacuum cups contact the body of the container diametrically and at least two and preferably three or more vacuum cups contact the container axially. In addition, the vacuum cups are in substantial tangential relationship. In order to maximize contact, the vacuum cups are provided in rows extending transversely of the conveyor belt and which rows are inclined at an angle to the direction of movement of the vacuum conveyor as best seen in FIG. 4. As each pair of containers C fall from the open mold when the vacuum is released holding the container in the upper mold, the pair of containers is immediately grabbed by the vacuum cups so that the axes of the containers remain parallel to that of the mold so that any rotation about the axis of the container is prevented. As a result, the moil M remains horizontal as it was in the mold. Each pair is thus oriented and spaced for direct delivery on the trimming apparatus such as shown in the U.S. Pat. No. 4,616,018.

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BACKGROUND OF THE DISCLOSURE 1. Field of the Disclosure The subject disclosure relates generally to oilfield drilling, and more particularly to bottom hole assemblies and tools for orienting a bottom hole assembly (BHA). 2. Background of the Related Art In conventional drilling, the BHA is lowered into the wellbore using jointed drill pipes or coiled tubing. Often the BHA includes a mud motor, directional drilling and measuring equipment, measurements-while-drilling tools, logging-while-drilling tools and other specialized devices. A simple BHA having a drill bit, various crossovers, and drill collars is relatively inexpensive, costing a few hundred thousand US dollars, while a complex BHA costs ten times or more than that amount. Many drilling operations require directional control so as to position the well along a particular trajectory into a formation. Directional control, also referred to as “directional drilling,” is accomplished using special BHA configurations, instruments to measure the path of the wellbore in three-dimensional space, data links to communicate measurements taken downhole to the surface, mud motors, and special BHA components and drill bits. The directional driller can use drilling parameters such as weight-on-bit and rotary speed to deflect the bit away from the axis of the existing wellbore. In some cases, e.g. when drilling into steeply dipping formations or when experiencing an unpredictable deviation in conventional drilling operations, directional-drilling techniques may be employed to ensure that the hole is drilled vertically. Direction control is most commonly accomplished through the use of a bend near the bit in a downhole steerable mud motor. The bend points the bit in a direction different from the axis of the wellbore when the entire drill string is not rotating. By pumping mud through the mud motor the bit rotates (though the drill string itself does not), allowing the bit alone to drill in the direction to which it points. When a particular wellbore direction is achieved, the new direction may be maintained by then rotating the entire drill string, including the bent section, so that the drill bit does not drill in a direction away from the intended wellbore axis, but instead sweeps around, bringing its direction in line with the existing wellbore. As it is well known by those skilled in the art, a drill bit has a tendency to stray from its intended drilling direction, a phenomenon known as “drill bit walk”. A device for addressing drill bit walk is shown in U.S. Pat. No. 7,610,970 to Sihler et al. issued Nov. 3, 2009, which is incorporated herein by reference. The use of coiled tubing with downhole mud motors to turn the drill bit to deepen a wellbore is another form of drilling, one which proceeds quickly compared to using a jointed pipe drilling rig. By using coiled tubing, the connection time required with rotary drilling is eliminated. Coiled tube drilling is economical in several applications, such as drilling narrow wells, working in areas where a small rig footprint is essential, or when reentering wells for work-over operations. In coiled tubing drilling, a BHA with a mud motor is attached to the end of a coiled tubing string. Typically, the mud motor has a fixed or adjustable bend housing to drill deviated holes. Because the coiled tubing is unable to rotate from surface, a so called orienter tool is used as part of the BHA to “orient” the bend of the mud motor into the desired direction. There exists a multitude of different designs for the drive systems of such tools. Some designs support continuous rotation such as electric motor and gearbox drives, while others only permit rotation by a certain limited angle. BRIEF DESCRIPTION OF THE DRAWINGS So that those having ordinary skill in the art to which the disclosed system appertains will more readily understand how to make and use the same, reference may be had to the following drawings. FIG. 1A is a cross-sectional view of a distal portion of a bottom hole assembly with an orienter tool in accordance with the subject technology. FIG. 1B is a cross-sectional view of a proximal portion of a bottom hole assembly with the orienter tool in accordance with the subject technology. FIG. 2 is a partial cross-sectional view of another embodiment of an orienter tool in accordance with the subject technology. FIG. 3 is a schematic illustration of a drilling system having a bottom hole assembly utilizing an embodiment of the orienter tool. DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS The present disclosure overcomes many of the prior art problems associated with directing or orienting a bottom hole assembly in coiled tubing applications. The advantages, and other features of the orienting tool disclosed herein, will become more readily apparent to those having ordinary skill in the art from the following detailed description of certain preferred embodiments taken in conjunction with the drawings which set forth representative embodiments of the present invention and wherein like reference numerals identify similar structural elements. All relative descriptions herein such as left, right, up, and down are with reference to the Figures, and not meant in a limiting sense. Unless otherwise specified, the illustrated embodiments can be understood as providing exemplary features of varying detail of certain embodiments, and therefore, unless otherwise specified, features, components, modules, elements, and/or aspects of the illustrations can be otherwise combined, interconnected, sequenced, separated, interchanged, positioned, and/or rearranged without materially departing from the disclosed systems or methods. Additionally, the shapes and sizes of components are also exemplary and unless otherwise specified, can be altered without materially affecting or limiting the disclosed technology. The subject technology is directed to a mechanical, coiled tubing orienter tool. The orienting rotation is accomplished by using a dual-spline drive, where the driving spline uses a relatively small pitch, and the driven spline uses a relatively large pitch. The difference in pitch provides a means of mechanical power transmission to convert high speed/low torque (e.g. typical for an electric motor) into a low-speed/high torque output. The orienter also can be wired, either by adding a slip-ring type electrical connector box or by stretching a wire from top to bottom inside the flow bore if the rotation is non-continuous. Another embodiment of the present invention includes an orienter tool for a bottom hole assembly (BHA) having an output shaft used in selecting drilling direction. The orienter tool includes an elongated housing defining an interior. A dual-spline drive mounts within the interior. The dual-spline drive includes a first lead screw portion with first threads having a first pitch, a second lead screw portion with second threads having a second pitch, the second pitch being different from the first pitch, a lead screw drive nut held axially fixed about the first lead screw portion and rotationally free within the interior of the housing, and a driving bushing free to move axially along the second lead screw portion which is connected to the output shaft. A motor is connected to the dual-spline drive for rotation thereof. A straight spine mounts about the drive bushing and constrains rotation thereof. When the lead screw nut is rotated, the drive bushing is pushed axially proximally or distally depending upon a direction of rotation and, in turn, the drive bushing imposes a rotation upon the output shaft. In this embodiment, the second pitch is relatively larger than the first pitch. The difference in rotational angle or speed between the lead screw drive nut and the output shaft is equal to a mechanical transmission ratio of the orienter tool. The orienter tool also may include a gear box connected between the motor and the lead screw drive nut, wherein the gear box is substantially not back-drivable, and/or a slip ring connector box for wiring the BHA in an annular fashion in conjunction with a through-bore defined in the interior. In another embodiment, the driving bushing has a portion of free twisting length. In one embodiment, a twisting stiffness of the portion of the free twisting length of the driving bushing approximately matches a twisting stiffness of the output shaft. The present technology also is directed to a method for orienting a bottom hole assembly having an output shaft and an elongated housing defining an interior. The method comprises mounting a dual-spline drive within the interior. The dual-spline drive includes a first lead screw portion with first threads of a first pitch and a second lead screw portion with second threads of a second pitch, the second pitch being different from the first pitch. The method also comprises axially fixing a lead screw drive nut held about the first lead screw for engagement with the first threads, wherein the lead screw drive nut is rotatable within the interior of the housing and driven by motor. The method may further comprise mounting a drive bushing which is free to move axially along the second lead screw for engagement with the second threads, and connecting the second lead screw to the output shaft. The method also may comprise mounting a straight spline about the drive bushing within the interior to constrain rotation thereof, and rotating the dual-spline drive such that as the lead screw drive nut is rotated, the drive bushing is pushed axially proximally/distally depending upon a direction of rotation. In turn, the drive bushing imposes a rotation upon the output shaft. It should be appreciated that the present technology can be implemented and utilized in numerous ways, including without limitation as a process, an apparatus, a system, a device, a method for applications now known and later developed. These and other unique features of the system disclosed herein will become more readily apparent from the following description and the accompanying drawings. In brief overview, the subject technology is directed to a mechanical coiled tubing orienter tool and methods for using the same. The orienting rotation of the BHA is accomplished by using a dual-spline drive in which a first lead screw drive nut is held axially fixed and rotationally free inside the orienter housing. The dual-spline drive is powered by an electric motor and an optional gearbox. When this lead screw drive nut is rotated, the drive bushing is pushed axially down or up, depending on lead screw direction. The drive bushing is constrained against rotation by, for example, a straight spine. When the drive bushing is pushed axially, the drive bushing imposes a rotation of the output shaft by way of a second lead screw drive with a relatively large pitch. The difference in rotational angle or speed between the lead screw drive nut and the output shaft is equal to the inherent mechanical transmission ratio of the design. Referring generally to FIGS. 1A and 1B , cross-sectional views of a distal portion 102 and a proximal portion 104 , respectively, of a bottom hole assembly (BHA) 100 are illustrated as having an orienter tool 110 in accordance with the subject technology. Matching lines 1 A and 1 B illustrate how to properly connect the distal portion 102 and the proximal portion 104 of FIGS. 1A and 1B , respectively, to form a continuous cross-sectional view. The BHA 100 comprises coiled tubing or an elongated housing 106 that forms an interior 108 containing the orienter tool 110 and other components. The BHA 100 comprises a fluid swivel device 112 through which the drilling mud and/or water passes centrally. An electric wire 114 passes to an electrical connector box 116 for passing power and for exchanging signals with the BHA 100 . In the example illustrated, the orienter tool 110 comprises a dual-spline drive 118 powered by an electric motor 120 and an optional gearbox 122 mounted about a shaft/tube 124 . The positions of the electric motor 120 and shaft 124 are monitored by sensors, such as a motor encoder 126 and a shaft encoder 128 , respectively. In the embodiment illustrated, the motor 120 is connected to the gearbox 122 to operate a dual-spline 130 . A first lead screw drive portion 132 of the dual-spline 130 has first threads 134 having a first pitch. A second lead screw drive portion 136 has second threads 138 having a second pitch which is different from the first pitch. In the embodiment shown, the second threads 138 have a relatively larger pitch than the first threads 134 , e.g. 2-100 times larger, 100-1000 times larger, or more than 1000 times larger. As illustrated, a lead screw drive nut 140 is mounted axially fixed about an axially movable portion 141 of the first lead screw drive portion 132 to engage the first threads 134 on movable portion 141 . The lead screw drive nut 140 is rotatable within the interior 108 of the housing 106 via motor 120 and gear box 122 to selectively move portion 141 in an axial direction. A driving bushing 142 is engaged by movable portion 141 and is free to move axially along the second lead screw drive portion 136 while engaging the second threads 138 . The driving bushing 142 connects to an output drive shaft 144 of the BHA 100 via the second lead screw drive portion 136 . A straight spline 146 mounts about the drive bushing 142 to constrain rotation thereof. The output drive shaft 144 defines a fluid bore 148 also for carrying drilling mud flow as shown by the arrows “a”. An electrical cable 150 may be positioned in the fluid bore 148 for passing signals, power and the like. In the case of a slip-ring type connector box configuration, an appropriately shielded wire or electrical cable 150 may be stretched through the fluid bore 148 without the use of electrical connector box 116 . As a result, the electrical cable may cope with a smaller twisting angle of the orienter tool 110 e.g. an angle of +/−200 degrees. In some embodiments, a slip-ring type connector box 152 (shown partially in dashed lines) may be used when, for example, the orienter tool is constructed in an annular fashion so that a continuous through-bore may be provided through large portions or through the entire length of the orienter tool 110 . In the embodiment illustrated, the orienting rotation of the BHA 100 is accomplished by using the dual-spline drive 118 . When the lead screw drive nut 140 is rotated via motor 120 working in cooperation with gear box 122 (in this embodiment), the drive bushing 142 is pushed axially down or up (depending on the direction of the lead screw rotation) via axial movement of movable portion 141 . The drive bushing 142 may be constrained against rotation by straight splines 146 . When the drive bushing 142 is pushed axially, the drive bushing 142 imposes a rotation of the output drive shaft 144 by way of the second lead screw portion 136 . A difference in rotational angle or speed between the lead screw drive nut 140 and the output drive shaft 144 occurs because of the difference in pitch of the threads 134 , 138 on the lead screw drive portions 132 , 136 , respectively. The difference in rotational angle is equal to the inherent mechanical transmission ratio of the dual-spline design. For example, if the first lead screw drive portion 132 has a pitch of 0.5 mm and the second lead screw drive portion 136 has a pitch of 0.5 m, a mechanical transmission ratio of 1000:1 is accomplished. To further manipulate the mechanical transmission, the gear box 122 between the electric motor 120 and the lead screw drive nut 140 may be employed. As an additional benefit, if the gear box 122 is not back-drivable, the BHA 100 does not require a separate brake. Referring generally to FIG. 2 , a partial cross sectional view of another embodiment of a BHA 200 in accordance with the subject technology is illustrated. As will be appreciated by those of ordinary skill in the pertinent art, the BHA 200 utilizes similar principles to the BHA 100 described above. Accordingly, like reference numerals preceded by the numeral “2” instead of the numeral “1” are used to indicate like elements. The primary difference of the BHA 200 in comparison to the BHA 100 is use of elastic averaging to even out forces imposed on the BHA 200 . When a large torque is exerted on a tubular structure, the result is elastic deformation in the form of twisting. Such twisting can result in uneven engagement and thus uneven contact forces in areas such as the distal region of the second lead screw drive portion 236 . Furthermore, uneven engagement forces can lead to uneven and increased wear which sometimes results in component failure. To cope with uneven engagement forces, drive bushing 242 utilizes a first portion 243 of free “twisting” length where the drive bushing 242 is not engaged with the straight spline 246 . The drive bushing 242 also utilizes a second portion 245 which is engaged with the straight spline 246 . The twisting stiffness of the free twisting length 243 of the drive bushing 242 may be selected to match the twisting stiffness of the drive shaft 244 . As a result, even engagement of the lead screw drive portion 236 is accomplished by way of such elastic averaging. Referring generally to FIG. 3 , an example of a well system 250 is illustrated as deployed in a well 252 defined by at least one wellbore 254 having at least one deviated wellbore section 256 being formed. Although the orienter tool 110 of bottom hole assembly 100 may be utilized in a variety of downhole systems to provide improved control over the orienting of a variety of components, a well drilling example is illustrated in FIG. 3 . In this example, the well system 250 includes a drilling system 258 comprising bottom hole assembly 100 delivered downhole by a suitable conveyance 260 , such as coiled tubing. In the embodiment illustrated, bottom hole assembly 100 includes the orienter tool 110 containing the dual-spline system 130 . The orienter tool 110 and its dual-spline system 130 may be used to ultimately control the drilling orientation of a drill bit 262 . In some drilling operations, the drill bit 262 is powered by a motor 264 , such as a mud motor. Depending on the application, the mud motor 264 may work in cooperation with a bent housing 266 and the orienter tool 110 to control the desired direction of drilling. As known to those of ordinary skill in the art, bottom hole assembly 100 may comprise a variety of other components, including steering components, valve components, sensor components, measurement components, drill collars, crossovers, and/or other components. The actual selection of components depends on, for example, the specifics of the drilling application and/or the characteristics of the environment. As would be appreciated by those of ordinary skill in the pertinent art, the subject technology is applicable to use in a variety of applications with significant advantages for bottom hole assembly applications. The functions of several elements may, in alternative embodiments, be carried out by fewer elements, or a single element. Similarly, in some embodiments, any functional element may perform fewer, or different, operations than those described with respect to the illustrated embodiment. Also, functional elements shown as distinct for purposes of illustration may be incorporated within other functional elements, separated in different hardware or distributed in various ways in a particular implementation. Further, relative size and location are merely somewhat schematic and it is understood that not only the same but many other embodiments could have varying depictions. Accordingly, although only a few embodiments of the present invention have been described in detail above, those of ordinary skill in the art will readily appreciate that many modifications are possible without materially departing from the teachings of this invention. Such modifications are intended to be included within the scope of this invention as defined in the claims.

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BACKGROUND OF INVENTION [0001] The invention relates to determining recommended maintenance intervals and particularly maintenance intervals for a fleet of units based on the operational profile of each unit. [0002] Power generation units, such as the units responsible for creating electrical power for utility companies, are regularly tasked with operating continuously for extended periods at high levels. The units need to toe considered to have a high level of reliability. Maintaining reliability under these requirements may be difficult since the components of power generation units are prone to deterioration with use, which may include wear, fatigue, cracking, oxidation, and other damage, and require regular maintenance. Deterioration that can lead to failure of a unit may be referred to as a failure mode. [0003] Power generation units generally include large components, many of which rotate in use and operate under extreme conditions, and are also subjected to large mechanical and electrical loads. Without proper maintenance, these units may degrade due to wear and will ultimately fail if not properly maintained. To avoid failure, the power generation units are taken off-line for periodic repair and maintenance under a regular schedule. [0004] Scheduling maintenance and repair of power generation units often includes setting an operational period during which a unit is continuously operated, the operational period lasting from a first event which takes the unit off-line for repair and/or maintenance until a second event which also takes the unit off-line for repair and/or maintenance. Determining the length of the operational period usually involves balancing the requirement for reliable operation of the unit and a need for continuous and extended operation. [0005] To perform repair and/or maintenance work on a power generation unit, the unit must be taken off-line. While off-line, the unit is not generating power for a power grid. If the operational period is allowed to be too long, the power unit may unexpectedly fail during operation. Such unexpected failure results in an unplanned outage of power generation, which reduces power output of a plant relying on the unit and may have a high cost in both monetary and human capital due to the suddenness and immediacy of the need for repair. On the other hand, shortening the operational period reduces the amount of time during which the unit is gene-rating power between repair and maintenance events and therefore reduces the total amount of power generated by the unit over an extended period such as the life of the power generation unit due to the more frequent off-line sessions. Another way to describe taking a unit offline is reducing “availability,” which may be described mathematically. Mathematically, “1” represents being available for an entire calendar year, which is 365 days. “0” would represent a unit which is offline for an entire year and is thus available for 0 days out of a year. To mathematically represent when a particular unit is available, a calculation may be made in the form of (1-(total downtime divided by total calendar time)), where total downtime is the sum of planned and unplanned downtime. Conventionally, a calculated likelihood of failure is used to determine an appropriate operational period for an industrial power generation unit that extends between planned off-line maintenance and repair events, The calculated likelihood of failure is then used to balance the requirement of maintaining a reliable power unit with the need for generated power. [0006] The calculated likelihood of failure may be characterized as a likelihood of the power generation unit suffering an unplanned outage. A power unit suffers an unplanned outage when the unit is taken off-line at a time other than a scheduled off-line period. The unplanned outage is typically due to a failure of a power generation unit operating in the field such as in a power generation plant. [0007] Unplanned outage likelihood is traditionally determined based on historical data of actual field failures of power generation units. Actual field failures are useful for estimating the likelihood of failure, but do not accurately account for all potential failure modes of the power generation unit. Some failure modes are not reflected in the historical failures of units. [0008] To model these other failure modes, a “lurking model” has conventionally been used. For example, the likelihood of previously unseen failure modes may be estimated using the lurking model. The lurking model approach is crude and is based on a hypothetical analysis of unforeseen and unseen modes of failures. A lurking model takes into account the likelihood associated with those unknown failure mode(s) of the system or system components which may occur in the future if the system or component is allowed to operate beyond the current operating experience. It is usually estimated using a Weibayes model, which is a type of Weibull model with no failure points, and in which a shape parameter (also known as “beta”) is assumed. A value of beta may be relatively high and may be in the range of 3 to 4. Generally, beta may be in the range of 1 to 4. The hypothetical analysis used in the lurking model may not anticipate actual unforeseen failure modes of a power generation unit. [0009] Conventionally, maximum intervals of operation may also be based on either the maximum amount of hours of operation or a maximum number of starts of a particular unit. The use of a maximum interval for hours or a maximum interval for starts results in an operational metric varying as a function of the operational profile of a specific unit in the fleet. The further a specific unit is from the maximum hours or starts limit, the less optimally it is being serviced. In other words, the unit could be operated for more hours or cycles than is allotted under current recommendations. [0010] Therefore, at a fleet level, units are being prematurely serviced due to conventionally recommended maintenance intervals. Conventional maintenance intervals, which are fixed, do not take into account the behavior of desired operational metrics as a function of unit operation. In some conventional solutions, an elliptical relationship is assumed between number of starts of systems and hours a system is running. In those elliptical solutions, units are often recommended to be serviced prematurely for part of the operational profile spectrum and conversely are recommended to be serviced later than the appropriate interval. [0011] There is a long felt and unsolved need for enhanced systems and methods to accurately assess the correct operational period for each individual unit within a fleet of units so as to maximize their value and minimize losses due to their being taken off-line unexpectedly. BRIEF DESCRIPTION OF INVENTION [0012] A method for determining recommended maintenance intervals for a fleet of units is based on the operational profile of each unit. Each unit in the fleet is run to a constant value of an operational metric regardless of operational profile. For example, operational metrics may include at least a constant likelihood of unplanned maintenance, costs of unplanned maintenance, reliability, availability, or even total lifecycle costs (including unplanned outage costs, repair costs, and fallout costs, etc.). Failure mode and effects analyses (FMEA) may be leveraged to ensure that all known and hypothetical failure modes are properly accounted for. [0013] A method for determining recommended maintenance intervals for a fleet of units is based on each unit in the fleet being run to the same value of an operational metric. As noted above, operational metrics may include a likelihood of unplanned maintenance, costs of unplanned maintenance, reliability of an individual unit, availability of replacement parts or replacement units, and total lifecycle costs for an individual unit or a fleet of units. [0014] Operational metrics may be directly linked to reliability models and/or data at the failure mode level for each component or subsystem of interest. [0015] As part of determining an appropriate operational period, models are created at the failure mode level for each component of interest. Typically, these models would result in the probability of an unplanned maintenance event for a given failure mode as a function of an operational parameter. These models may also include data for the consequences of the failure mode if it occurs, e.g., an event duration or cost of repair, etc. [0016] Models for all of the individual failure modes are combined to result in an operational metric of interest. An operational, metric “of interest” is a metric which a business wishes to maintain constant for each unit in the fleet. Examples of an operational metric of interest include, but are not limited to, a likelihood of unplanned maintenance, a cost of unplanned maintenance, reliability of a unit, availability of a unit, and a total lifecycle cost. [0017] Based on the models, the maintenance interval, i.e., the operational period, may be adjusted such that each operational profile results in the same value of the operational metric. For example, a curve may be generated which compares a number of starts with hours in operation for a particular unit or a fleet of units. Such a curve may indicate a maintenance interval for any given hours to starts ratio. [0018] Such a system may be re-evaluated within a boundary embodied in the above-discussed curve. Re-evaluation may be accomplished using a design evaluation tool such as Failure Modes and Effects Analysis (FMEA). Such a re-evaluation may determine if any new, hypothetical failure mode models should be added, given the new expanded boundary for the maintenance interval (relative to conventional methods). If any new failure models are identified, then their corresponding models are added and new models are recreated for all of the individual failure modes as discussed above. [0019] As a result, a recommended operational interval for each unit in a fleet of units is generated based on its individual operating profile, the individual operating profile maintaining the same value of an operating metric across all units in the fleet. [0020] Regarding reliability, empirical data of actual wear, degradation, and damage occurring in the machine may be used to enhance the modeling of machine failure modes. The model may be used to calculate the reliability of the machine and determine an optimal period between off-line maintenance and repair sessions. The model combines data from historical field failures and potential, also referred to as unforeseen, failures based on monitoring the machine, such as by boroscopic inspections. [0021] Reliability data may come in different forms, each of which nay require a different tool to measure, capture, and/or collect. Reliability data may include at least; A) Operational data, which may be automatically collected from each unit and/or may be transmitted to a central monitoring system; B) Cost data, which may be related to unplanned downtime and may be captured in a financial accounting system; and C) Field engineering reports, which may describe failure modes, including those that have occurred in the past. These examples are illustrative and non-limiting. [0022] Reliability data may be recorded on a variety of storage devices, which may function as intermediate storage devices prior to the data being consolidated into a final storage device. The intermediate and/or consolidated data may be used to create reliability models at the failure mode level. Storage devices may include at least: A) a first database system which may be used to store operational data automatically collected from each unit and/or transmitted to a central monitoring system; B) a second database system which may foe used to store financial accounting data; C) a server which may be used to store field reports that may have been created using conventional office software programs, such as word processing programs, and the reports may be created and/or stored as individual files; and D) a third database system may store reliability data compiled from multiple databases and/or storage devices. The databases may foe intermediate databases. These examples are illustrative and non-limiting. [0023] Analysis devices may be used to create models of data which has been collected regarding units within a fleet and/or the fleet as a whole. The analysis devices may be used to create models at the failure mode level for each component of interest from the reliability data. After models have been created, one or more analysis devices may be used to apply the created model(s) to predict future reliability, availability, unplanned cost, and other operational considerations. One or more analysis devices may also be used to evaluate those models in order to calculate a recommended fleet maintenance interval. For example, analysis devices may include at least: A) statistical analysis software used by a reliability engineer to iteratively create models at the failure mode level for each component of interest; B) spreadsheet-based software tools; C) stochastic simulation software; and D) personal computer, server, or cloud-based simulation software. These examples are illustrative and non-limiting. [0024] A power generation unit may include a gas turbine, a steam turbine, or another power generation device. BRIEF DESCRIPTION OF THE DRAWINGS [0025] FIG. 1 illustrates a process flow chart mapping steps for determining a recommended maintenance interval; [0026] FIG. 2 illustrates a graphical representation of a comparison of conventional maintenance intervals compared with recommended maintenance intervals according to the application; [0027] FIG. 3 illustrates an alternate graphical representation of a comparison of conventional maintenance intervals compared with recommended maintenance intervals according to the application; [0028] FIG. 4( a ) illustrates a graphical representation of an operating metric as a function of an operational profile according to conventional means; [0029] FIG. 4( b ) illustrates an alternate graphical representation of an operating metric as a function of an operational profile related to the graphical representation illustrated in FIG. 2 . [0030] FIG. 4( c ) illustrates yet another alternate graphical representation of an operating metric as a function of an operational profile related to the graphical representation illustrated in FIG. 3 . [0031] FIG. 5 illustrates a combined graphical representation illustrating a curve of FIG. 4( b ) alongside a curve of FIG. 4( c ) . DETAILED DESCRIPTION OF THE INVENTION [0032] FIG. 1 illustrates a process flow chart mapping steps for determining a recommended maintenance interval. As a first step 101 , failure mode models are created. In step 101 , models are created for each component of interest. The various failure mode models are then combined in step 102 to create a mathematical model, optionally illustrated as a graphical representation, of a particular operational metric of interest. After combining the various failure mode models generated in step 102 , a target operational metric is obtained in step 103 by calculating an operational metric at a target operational profile. [0033] With the target operational metric obtained in step 103 , the operational profile may then be incremented in step 104 . In the incrementation of step 104 , the maintenance interval may be adjusted such that each operational profile results in the same value of the operational metric. After the incrementation of step 104 , an operational metric may be calculated at the new operational profile In step 105 . After the new operational metric is calculated in step 105 , the operational metric is compared with a target operational metric in step 106 . If the operational metric calculated in step 105 is not equal to a target operational metric, the system may enter an optimization loop, whereby the maintenance interval is adjusted in step 107 followed by a new calculation of an operational metric at the newest operational profile in step 105 . [0034] If, on the other hand, the operational metric is found to be equal, within a desired tolerance (for example, +/−0.1%), to the target operational metric in step 106 , the system may then consider whether other operational profiles need to be evaluated as part of the process of determining maintenance intervals in step 108 . If the system or an operator of the system determines that other operational profiles need to be evaluated, the operational profile may again be incremented as in step 104 . If the operational profile is again incremented in step 104 , a new operational metric is again calculated at the newest operational profile in step 105 , followed by the comparison in step 106 . [0035] If, on the other hand, it is determined that no other operational profiles need to be evaluated in step 108 , the system may then be evaluated within a new recommended maintenance interval using, e.g., FMEA procedures, in step 109 . [0036] After an evaluation of the system in step 109 , the system or an operator of the system determines whether any other failure modes need to be modeled due to extended operation in step 110 . If step 110 determines that yes, additional failure modes need to be modeled, the new additional models are combined with ail the other models already considered in step 102 . The system then proceeds through the steps outlined above with the new additional model(s) combined in step 102 . If, however, step 110 determines that no other failure modes need to be modeled or considered, the system is completed and a maintenance interval is determined in step 111 . [0037] FIG. 2 illustrates a graphical comparison between conventional maintenance periods in curve 201 and a curve 202 based on the operational metric of the present application. In this figure, the vertical axis comprises a measure of factored fired starts 203 for a power generation unit. The horizontal axis comprises a measure of factored fired hours 204 for the power generation unit. Curve 202 is illustrated as an iso-value curve for an operational metric. In this particular example, the operational metric is set equal to the value of the operational metric of the prior art (conventional) hours and starts maintenance interval, as indicated at point 205 . [0038] Line 208 illustrates an example “unit A” being considered for when to take unit A offline for scheduled maintenance. Point 209 illustrates the conventional point at which unit A would be taken offline, while point 210 illustrates a point according to the present technology when unit A would be taken offline. According to conventional methods, as soon as unit A had been started 1200 times, the unit must be taken offline, regardless of how many hours the unit had actually been in operation. [0039] Line 211 illustrates, another example “unit B” being considered for when to take unit B offline for scheduled maintenance. According to conventional methods, as soon as unit B reached 32000 hours in service, regardless of the number of fired starts, unit B would be taken offline. Similarly, point 212 illustrates a point at which unit B would be taken offline for maintenance according to conventional methods, while point 213 illustrates a point according to the present technology when unit B would be taken offline. [0040] As illustrated in FIG. 2 , the area 206 , 207 between curve 201 and curve 202 represents additional unit operation that becomes possible using the system described herein. The dashed section of line 208 illustrates the added operational time of unit A as a result of the present technology. The dashed section of line 211 illustrates the additional operational time of unit B as a result of the present technology. [0041] FIG. 3 illustrates a graphical comparison between conventional maintenance periods in curve 301 and a curve 302 based on the operational metric of the present application, similar to the curves illustrated in FIG. 2 . In FIG. 3 , the vertical axis comprises a measure of factored fired starts 303 for a power generation unit. The horizontal axis comprises a measure of factored fired hours 304 for the power generation unit. FIG. 3 also illustrates a third curve 308 , which is also an iso-value curve for the operational metric, but with the operational metric set to a value below the operational metric that resulted in curve 302 . As indicated by arrow 309 , setting the operational metric to a lower value shifts the curve representing an improved maintenance interval determined herein by the present application. For example, curve 302 may represent an operational metric set to a likelihood of an unplanned outage or failure at approximately 30%, while curve 308 may represent a likelihood of an unplanned outage or failure at approximately 25%, which represents a lowered likelihood that a unit in a fleet of units will experience a failure. [0042] Similar to FIG. 2 , area 306 , 307 represents additional unit operation that becomes possible relative to the conventional maintenance interval determination. Due to the shift in curve 308 , area 306 , 307 is smaller than area 206 , 207 illustrated in FIG. 2 . Curve 308 represents a recommended maintenance interval for the fleet with a reduced likelihood of failure as compared to Curve 302 . [0043] FIG. 4( a ) illustrates a graph of an operating metric as a function of an operational profile according to prior art. Here, as an exemplary operating metric, the “likelihood of unplanned outage” is used. The exemplary operating profile comprises an “N ratio” defined as Factored Fired Hours/Factored Starts. Other operating metrics or operating profiles may be used. FIG. 4( a ) has a vertical axis 403 comprising Y, an operating metric. In FIG. 4( a ) , the operating metric is illustrated as a likelihood of an unplanned outage, expressed as a percentage probability. FIG. 4( a ) also has a horizontal axis 404 comprising X, an operational profile. The operational profile is illustrated as the N ratio defined above as Factored Fired Hours/Factored Starts. Curve 412 illustrates an example likelihood of an unplanned outage due to failure modes dependent on the number of hours a power generation unit has been in operation. Curve 413 illustrates an example likelihood of an unplanned outage due to failure modes dependent on the number of factored starts for a power generation unit. Curve 411 is a combined curve illustrating a total probability of an unplanned outage as a function of the operational profile. [0044] FIG. 4( b ) illustrates a graph of an operating metric as a function of an operational profile according to the operating profile illustrated In FIG. 2 . Here, as in FIG. 4( a ) , as an exemplary operating metric, the “likelihood of unplanned outage” is used. The exemplary operating profile comprises an “N ratio” defined as Factored Fired Hours/Factored Starts. Other operating metrics or operating profiles may be used. FIG. 4( b ) has a vertical axis 403 comprising Y, an operating metric. In FIG. 4( b ) , the operating metric is illustrated as a likelihood of an unplanned outage, expressed as a percentage probability. FIG. 4( b ) also has a horizontal axis 404 comprising X, an operational profile. The operational profile is illustrated as the N ratio defined above as Factored Fired Hours/Factored Starts. Curve 422 illustrates an example likelihood of an unplanned outage due to failure modes dependent on the number of factored fired hours a power generation unit has been in operation. Curve 423 illustrates an example likelihood of an unplanned outage due to failure modes dependent on the number of factored starts for a power generation unit. Curve 421 is a combined curve illustrating a total likelihood of an unplanned outage as a function of the operational profile. [0045] FIG. 4( c ) illustrates a graph of an operating metric as a function of an operational profile according to the operating profile illustrated in FIG. 3 . Here, as in FIG. 4( a ) , as an exemplary operating metric, the “likelihood of unplanned outage” is used. The exemplary operating profile comprises an “N ratio” defined as Factored Fired Hours/Factored Starts. Other operating metrics or operating profiles may be used. FIG. 4( c ) has a vertical axis 403 comprising Y, an operating metric. In FIG. 4( c ) , the operating metric is illustrated as a likelihood of an unplanned outage, expressed as a percentage probability. FIG. 4( c ) also has a horizontal axis 404 comprising X, an operational profile. The operational profile is illustrated as the N ratio defined above as Factored Fired Hours/Factored Starts. Curve 432 illustrates an example likelihood of an unplanned outage due to failure modes dependent on the number of factored fired hours a power generation unit has been in operation. Curve 433 illustrates an example likelihood of an unplanned outage dependent on the number of factored starts for a power generation unit. Curve 431 is a combined curve illustrating a total likelihood of an unplanned outage as a function of the operational profile. [0046] FIG. 5 illustrates a graph of an operating metric as a function of an operational profile according to the operating profiles illustrated in FIGS. 2-3 . Here, as in FIG. 4( a ) , as an exemplary operating metric, the “likelihood of unplanned outage” is used. The exemplary operating profile comprises an “N ratio” defined as Factored Fired Hours/Factored Starts. Other operating metrics or operating profiles may be used. FIG. 5 has a vertical axis 503 comprising Y, an operating metric. In FIG. 5 , the operating metric is illustrated as a likelihood of an unplanned outage, expressed as a percentage probability. FIG. 5 also has a horizontal axis 504 comprising X, an operational profile. The operational profile is illustrated as the N ratio, defined above as Factored Fired Hours/Factored Starts. [0047] FIG. 5 juxtaposes total likelihood of an unplanned outage according to the prior art in curve 511 , according to the maintenance interval illustrated as line 202 in FIG. 2 in curve 521 of FIG. 5 , and according to the maintenance interval illustrated as line 308 in FIG. 3 in curve 531 of FIG. 5 . [0048] While the invention has been described in connection with what is presently considered to be the most practical and preferred embodiment, it is to be understood that the invention is not to be limited to the disclosed embodiment, but on the contrary, is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims.

4y

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electric wheel-drive for motor vehicles, especially for passenger cars with internal combusion engine, with individual brushless polyphasic electric motors attached to the wheels and electronically controlled in frequency. 2. Purpose of the Invention Aim of the present invention is the simple, inexpensive and reliable, nondestructive, mass-hybridization of motor vehicles with internal combustion engine, in particular automobiles, through the additional installation of 2 electric wheel-drives without modification of the wheels, the axle, or of other parts of the car, the drives being energized by a battery which is included for this purpose, resulting in two independent propulsion systems. 3. Description of the Prior Art In the Journal "Elektrotechnik und Maschinenbau" (Austria) No. 8 (August 1976) pp. 335-341 a special electric streetcar was disclosed with large-diameter electric wheel-hub motors on two individual very large wheels at the middle of the streetcar, one small support wheel in front, and one in the back. The propulsion is exclusively electric, the motors being fed by a generator driven in turn by an internal combustion engine, with a battery also included. This system is not suitable for a nondestructive mass-hybridization of conventional cars. Through the British patent GB-PS1246354 a motor vehicle with wheels driven in principle by electric motors was disclosed. The propulsion is exclusively electric, and the electric motors are fed by a generator driven by a gas turbine, or by a battery. This system also does not provide any suggestions for a nondestructive mass-hybridization of conventional cars in terms of two independent propulsion systems. In the disclosure DE-OS 2802753 (F.R. Germany) a heteropolar synchronous motor for vehicle propulsion was presented. Neither can a suggestion for the problem of nondestructive mass-hybridization of motor vehicles with internal combustion engine be found in DE-OS 2802753 nor can this be accomplished with the synchronous motor described there. Taking into account the considerable insecurity and fluctuation in the gasoline supply, as well as polution control, energy conservation, and the large waste of fuel on the daily short distance trips from home to work, a reversible, non-destructive means of transforming the car into a gasoline-electric (parallel-type) hybrid is definitely needed today, both at the level of the car manufacturer and at the dealer shop ("while you wait"). SUMMARY OF THE INVENTION Accordingly, the task underlying the invention, and the object of the invention, is to create a wheel-drive of the kind described in the beginning, which is simple and robust in operation, easy and fast to install, transferable among similar cars, and which reduces gasoline consumption, even to zero for short-distance traffic corresponding to the limitations in battery capacity. This task is performed by the invention through homopolar multiple-airgap axial field motors whose rotors replace the drum of the brake, or the disks if disk brakes were present, and whose stator replaces the brake-shoes and the splash plates of at least two wheels with the same axle of a conventional car, and through the inclusion of an electronic control system for the propulsion and braking operation modes of the motors. Such an axial-field motor is robust and can be installed very fast. The axial-field motors replacing two of the brakes, and the control are put in in very short time and connected with the battery. The transformation can be reversed at any time. The car receives an independent second propulsion system according to this invention. All-wheel traction, useful in snow conditions, can be obtained by electrifying the non-motor wheels. The rotor of the axial-field motor is appropriately composed of an axially magnetized or nonmagnetic supporting tube located on bearings on the axle, of a tubular permanent magnet of high-energy-density material with essentially axial magnetization clad on it, of frontally adjoining forged iron disks of which the one located at the external side of the wheel carries the screws holding the wheel, and of pole-rings put on the permanent magnet peripherically and comprising both stars of support arms and axially-magnetized pole-pieces of high-energy-density material at the free ends of the support arms. The tubular permanent magnet may be composed of hollow-cylindrical sectors, and/or annular disks. The stator of the axial-field motor is composed best of a pot-shaped casing and of support-elements fixed inside, on the casing, and extending inward, which carry flat ring-shaped coils located in the air-gaps between the pole-pieces. This yields a particularly compact and stable body. The permanent magnet and the pole pieces are suitably consisting of a samarium-cobalt alloy. The ring-shaped coils are profitably made of lamellar windings, or they are bobbin-wound coils of ribbon conductor. In a particularly advantageous embodiment the axial-field motor has five pole rings and six airgaps. The number of pole rings (and airgaps) is determined for each vehicle by the space available on the axle. The motor has preferably eight poles and a tri-phase winding. Hall-effect switches are suitably located in the motor for control. In the case of an eight-pole axial-field motor with balanced three-phase winding, the Hall-effect switches are mounted with an angle of 15° between them on the stator. The electronic control system is profitably connected for the regulation of the motor in three modes of operation: propulsion, regenerative braking, and resistive braking. Furthermore, the control preferably contains a programmable read only memory (PROM) which receives various driving, state of the system, and security signals and emits control signals. In an advantageous embodiment the electronic control is constructed with silicon controlled rectifiers (SCR). The electronic control can be appropriately switched on with a 3 position switch for forward operation, exclusively braking, and reverse operation of the axial-field motors. BRIEF DESCRIPTION OF THE DRAWINGS The invention is further explained below in terms of examples of embodiment with the help of drawings. In the drawings: FIG. 1 is a schematic axial section view of an axial field motor according to the invention; FIG. 1A is a view in perspective of one illustrative motor vehicle in which the motor of FIG. 1 finds application. FIG. 2 is a frontal view of the rotor of the motor in FIG. 1 at a smaller scale, with the Hall effect switches pointed out; FIG. 3 is a schematic cross-section through a star of support arms with pole-pieces of the motor in FIG. 1. FIG. 4 is a lamellar (ribbon) winding of the ring-coils in FIG. 1; FIG. 5 is a representation of the switching sequence and output signals of the Hall switches in FIG. 2; FIG. 6 is the scheme of a circuit with silicon controlled rectifiers (SCR) the control of the axial-field motor in FIG. 1; FIG. 7 is a schematic representation of the currents in the three phases of the motor in FIG. 1; FIG. 8 is a representation of the digital processor controlling the scheme in FIG. 6. DESCRIPTION OF THE PREFERRED EMBODIMENT The brushless homopolar axial-field motor represented in FIGS. 1 to 3 is triphasic, has eight poles, and exhibits six about 8 mm wide airgaps. It comprises a rotor 1 and a stator 2, the stator 2 being connected to a source of electrical energy by suitable lead wires L, L', and L" as shown in FIG. 1. The rotor 1 replaces the brake drum or brake disk, and the stator 2 replaces the brake shoe assembly or brake pads together with the brake back plate or brake splash shield, without changes in the wheel-axle 3. The rotor 1 contains an axially magnetized, or non-magnetic, support tube 5. In the case of motor-driven wheels, the rotor 1 is solid with the (rotating) axle of the wheel, and the bearings 4 are missing. A tubular permanent magnet 6 of highest energy density and with predominantly axial magnetization is set on the support tube 5. The permanent magnet 6 may be composed of annular disks or annular sectors. It is suitably composed of a samarium-cobalt (or similar) material with energy density of 2.10 5 J/m 3 or higher. Forged iron annular-stellar disks 7, for example, 1.9 cm thick, adjoin the permanent magnet 6 frontally. The forged iron disk facing the external side of the wheel carries the screws 8 holding the wheel, as indicated on FIGS. 1 and 2. The predominantly axially magnetized permanent magnet 6 can exhibit, towards its ends adjoining the forged iron disks, a gradually increased radial component of the magnetization, pointing outward. Five pole rings 9 shaped in the form of stars of support arms with axially magnetized pole-pieces 11 of high energy density attached to the free ends of the support arms 10, are set on the permanent magnet 6. The pole pieces 11 can also be made of samarium-cobalt material, or, e.g., of an iron-aluminum-nickel-cobalt alloy (5.10 4 J/m 3 ). Between the pole-rings 9, light metal plastic or poured resin rings can be applied as additional fasteners. The support arms 10 themselves are made of non-magnetic material and are slightly slanted to provide ventilation. The stator 2 of the axial-field motor is composed of a pot-shaped casing 13 fastened on the wheel-axle and steering knuckle. Some openings are present on the bottom of the pot-shaped casing for ventilation and cooling. In the case of motor wheels the casing rests on the bearings which support the (rotating) axle. Six ring-shaped support elements 14, each of them carrying a flat ring-shaped coil 15 protruding into the airgap between the pole-pieces 11, are fixed in the case, extending inwards. On the inner side of the ring-shaped coils there are support rings 16. The support elements 14 and the support rings 16 are fastened to the corresponding flat ring-shaped coil 15 e.g., by pouring a hardening agent. The ring-shaped bobbin-wound armature coil 15 can be made suitably of lamellar windings 17 as shown in FIG. 4, with the use of ribbon conductor. Each of the six ring-shaped coils 15 contains three phases spatially displaced by 15° from each other and connected for all six ring-shaped coils in series such that only three power leads are leaving the motor. The winding is connected preferably in star. The axial-field motor is homopolar, since the lines of force are passing through the pole-pieces 11 everywhere in the same direction. The magnetic flux density in the airgap is about 0.8 Tests. For a current of 250A the motor develops a torque of about 330 Nm. A power of about 20 KW is thereby obtained at a frequency of 600 rotations/m which corresponds to an applied voltage of 100 V. Usually there would be two axial-field motors installed in any car at the otherwise not propelled wheels, yielding 40 KW together. For a small car weighing 1000 Kg (including the batteries), with a diameter of the wheels of 0.5 m the speed developed is then about 100 km/h or 62.5 m.p.h. Due to the limited available torque, the highest slope accessible to the car without use of the internal combustion engine is about 15%. The acceleration time from rest to 50 km/h (31 m.p.h.) is about 8 s. A control system and a battery are needed for the operation of the axial-field motor. The control system is constructed with solid-state components and performs two main functions. (a) Switching the current for the three phases in the right sequence, such that all radially oriented conductors in the three-phase winding contribute positively to the torque while they are in the airgap. This switching process is triggered by three Hall-effect switches H1,H2,H3 (FIG. 2) placed on the stator 2 in spatial intervals of α=15° in order to sense the position of the rotor. The switching cycle of the Hall switches is represented in FIG. 5. (b) Control of the current absorbed by the motor and of the torque generated in the motor. The torque is proportional to the current. The battery contains, e.g., 18 lead or iron-nickel batteries of 6 V, or the same number of 12 V-batteries, the first choice being particularly favorable for the case of 120 V power outlets being used with a transformerless charger for overnight recharging, or used without charger, by simply switching from the motor M in FIG. 6 to the power outlet (not shown). During driving or regenerative braking the batteries can be switched automatically, depending on the frequency of the signals given by the Hall switches H 1 -H 3 to the PROM, i.e., depending both on motor speed and on whether the gas pedal or the brake pedal is depressed, in six parallel groups of three batteries in series (18/36 V), in three parallel groups of six batteries in series (36/72 V), in two parallel groups of nine batteries in series, or all in series (108/215 V). The batteries, located for instance in the trunk of the car, are weighing at this time about 300 kg and provide the car with an action radius of about 80 km without the use of the internal combustion engine. The engine is to be used for longer trips. With the battery taken out, only the resistive braking mode of operation can be used. Removal of the battery is recommended for extended, or trans-continental trips. FIG. 6 shows a circuit in the power control, which allows for driving, regenerative braking, and resistive braking operation of the axial-field motor. The circuit is connected through an ammeter I and a main switch H to the battery. The capacitor C is parallel to the entrance and reduces the ripple. Then a second switch A follows. Parallel to the capacitor C is the series connection of a transistor-diode chopper combination TM, DM, a braking resistor and a transistor-diode chopper combination TB, DB. The transistor-diode chopper combination TM, DM is for current limitation and control in the driving mode, and the chopper TB,DB is for current limitation and control in the resistive braking mode. Parallel to the chopper TM,DM there is an inductor L and a safety-diode D which eliminates possible high voltage transients. After the circuit mentioned above, in FIG. 6 there follows a bridge of six transistor-diode combinations T1D1,T2D2,T3D3,T4D4,T5D5 and T6D6 which are connected with the motor M. These six transistor-diode combinations are switched by the Hall-effect switches (through the PROM) and generate triphasic current. During regenerative braking the six diodes D1, D2, D3, D4, D5 and D6 work as a rectifier bridge and charge the battery B. The transistors TM, TB, and T1-T6 are preferably silicon controlled rectifiers (SCR). If n motors are present, this (bridge) part of the controller will be duplicated n times in parallel. A suitable choice of the currents J R J S and J T sent to the motor in the three phases in FIG. 5 is shown in FIG. 7. The steering of the control shown in FIG. 6 by the Hall switches H1, H2 and H3, by the gas and brake pedals of the car, and by the respective level of the motor current is performed advantageously through a PROM. The connections of such a PROM are presented in FIG. 8. The PROM receives signals from the Hall-switches H1, H2 and H3, a signal V/R corresponding to the choice of forward or reverse driving, a signal AP/BP from a gas pedal (accelerator) potentiometer or a brake pedal potentiometer, a signal TJ indicating possible thermal overloads of the motor M and the transistor TM, as well as a current level signal JV. From the output of the PROM leave the control signals for the transistors T1 to T6. Two other signals from the PROM control two oscillant circuits which determine the width and frequency of the rectangular opening-pulses for the transistor-diode chopper combinations TM and TB, respectively. In addition, the PROM emits several battery-switching signals. Due to the most likely presence of two motors (with independent phases) the upper part of the PROM in FIG. 8, and the connections H1-H3, T1-T6, and TJ will be duplicated in practice. This duplication is trivial and has been omitted in this text for the sake of simplicity. In the electric operation mode the driver controls the vehicle with the help of the gas pedal, of the brake pedal, and of the three-position switch for forward driving, exclusively (resistive, i.e., dynamical) braking, and reverse driving. From the three-position switch the signal V/R originates, depending on which position the switch is in. Braking is possible in all three positions, resistive (i.e., dynamical) braking even when the main switch H is open. The other parts of the control system are set in operation by closing the main switch H. This is suitably done in the "Garage" position of the ignition lock (which does not lock the steering wheel, but has the ignition off). In addition to their normal function, the gas and brake pedals are each connected mechanically with a potentiometer which also has a contact at the beginning of its way in the case of the gas pedal and a contact at the middle of its way in the case of the brake pedal. With the main switch H closed, if the gas pedal is depressed the switch A (FIG. 6) and the gas pedal contact arm (which switches the AP/BP signal) will close themselves after a short way of the pedal. In this position the gas potentiometer has the largest value of its resistance, and consequently the PROM opens the transistor TM only about 5% of the time (creep speed, to be adjusted at the oscillant circuit next to the PROM). If the gas pedal is further depressed, the width and repetition frequency of the rectangular "on"-signals finally increase, e.g. up to 3.10 -3 s and 300 Hz, respectively and the transistor TM will be open for about 90% of the time. At this point the transistor TM may be short-circuited by a direct switch (not shown on FIG. 6). The control can also be performed by making the gas potentiometer (or variable inductance), part of an oscillant circuit whose frequency it determines, and which in turn determines the repetition frequency and width of the "on"-signals for the transistor TM. The "on"-signals are further limited in width and frequency by thermal overload signals T1 which act on the oscillant circuit and are coming from the stator-windings of the axial-field motors and from the support of the transistor TM. If the gas pedal is left free, the car moves freely by virtue of its inertia. If the brake pedal is depressed, after a very short way a contact is closed switching the battery (through the PROM) to the series-parallel combination corresponding to the respective motor speed, similar to what happens if the gas pedal is depressed, but with a slightly different adjustment. Simultaneously, the switch A closes itself. Thereby the battery will be charged through the six diodes D1 to D6 in regenerative braking. At very low speeds, at which the battery can no longer be switched down, the regenerative braking action vanishes gradually. If the brake pedal is further depressed, both the hydraulic brakes (at the non-electric wheels) and resistive (dynamical) braking are initiated beyond a certain position S of the pedal. Resistive braking occurs, similar to the electric action of the gas pedal, by the closing of the brake potentiometer contact in the position S. At this initial position, somewhat before the middle of the pedal way, the brake potentiometer (or variable inductance) has its largest value, and therefore the PROM opens the transistor TB only for about 5% of the time. Resistive braking occurs with heat being generated mainly in the resistor R B , but also in the motors M, the transistor TB and in the wiring in parallel, i.e., additionally to the hydraulic brakes. The energy appearing in the case of stronger braking action is therefore distributed among battery, brake pads, and the resistor R B connected in series with the chopper combination TB, DB in FIG. 6. The control of the resistive braking is again accomplished, e.g., by making the brake potentiometer (or variable inductance) part of an oscillant circuit connected to the PROM, thereby controlling the frequency of the circuit, and indirectly the frequency and width of the "on" signals for TB. However, these signals are not limited additionally by thermal overload signals from the motors M and the support of the transistor TB, but these thermal overload signals activate only a red brake overload warning light in view of the driver on the dashboard. The ammeter I, with red maximal current marks on both sides, indicates the battery discharge current by deflection to the right and the charging current by deflection to the left in regenerative braking. The series-parallel battery-switching is controlled by the PROM both in driving and regenerative braking on the basis of the motor speed information derived from the Hall switches H1, H2 and H3, also taking into account the signal AP/BP. A different shaping of the axial-field motor, e.g. as disk motor, is considered as a poorer execution of the invention. All other modifications of mechanical or electrical nature within the framework of the claims are included in the protected domain of the invention. Obviously, numerous modifications and variations of the present invention are possible in light of the above teachings. It is, therefore, to be understood that within the scope of the appended claims, the invention may be practiced otherwise than specifically described herein.

4y

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to electrical connector shield cases and methods of making them, more particularly to an electrical connector shield case for covering the insulating housing of a plug or receptacle connector to make shielding contact to the shield member of another connector and a method of making it. 2. Description of the Prior Art Referring to FIG. 6A there is shown an electrical connector shield case 100' according to the prior art. In FIG. 6B, a base 103' of this shield case is secured to an insulating housing having male contacts 101' through an intermediate plate 102' so that the male contacts can be housed in an enclosure 104' which is integral with the base 103'. In use, the female contact of another connector is inserted into the enclosure 104' so that inner bosses 105' of the enclosure 104' can be brought into shielding contact with a shield member, such as a metal case, of the other connector. As FIGS. 7A through 7F show, the shield case 100' has been manufactured by pressing a metal sheet 10' having a size corresponding to that of the final product. A shield case element 40' is made by pressing the metal sheet 10' by means of a drawing press consisting of the lower die 20' with a projection 21' having a shape substantially identical with the shape of the enclosure 104' and the upper die 30' with a depression 31' having a shape substantially identical with the shape of the enclosure 104' (FIGS. 7B and 7C). The resulting shield case element 40', with a protruded portion 41' and a flange portion 42' is then pressed in another press consisting of the lower die 50' with a projection 51' having a cross section substantially identical with that of the protruded portion 41' and a depression 52' shaped corresponding to the periphery of the base 103' and the upper die 60' with a depression 61' having a cross section substantially identical with that of the protruded portion 41' and a projection 62' shaped corresponding to the periphery of the base 103' to open the top of the protruded portion 41' and cut the flange portion 42' to a predetermined shape (FIG. 7E). Then, bosses 105' are made by inserting a core die 70' having recesses 71' at positions corresponding to the bosses 105' of the shield case 100' into the protruded portion 41' of the shield case 100' and pressing the work between a pair of outer dies 80' and 90' each having projections 81' or 91' at positions corresponding to the bosses 105' in the direction of an arrow shown in FIG. 7F. This completes the formation of a shield case 100' such as shown in FIG. 6A. The manufacture of the above prior electrical connector shield case requires the drawing pressing porcess and has the following drawbacks: (1) The amount of material loss is large, increasing the material cost; (2) An extensible, soft material must be used, limiting the range of choices in material and failing to give satisfactory elasticity to the bosses of a case; (3) The extensible, soft material is susceptible to deformation under an external stress; (4) The thickness of a case wall varies from section to section. (5) The outward bosses are very difficult to make. SUMMARY OF THE INVENTION According to one aspect of the invention there is provided an electrical connector shield case for covering either protuberance or opening of an insulating housing with a plurality of contacts therein, which comprises (a) a cylindrical metal member; (b) at least one boss provided on the side of said cylindrical member so as to make shielding contact with the shield member of another connector; and (c) latch means provided on said cylindrical side for engaging with said insulating housing. In accordance with another aspect of the invention there is provided an electrical connector shield case wherein said latch means consists of a latch claw provided on said cylindrical side and a flange of said insulating housing. According to still another aspect of the invention there is provided an electrical connector shield case wherein said latch means consists of a tab provided on said cylindrical side and a slot provided on said insulating housing, into which said tab is fitted. In accordance with yet still another aspect of the invention there is provided an electrical connector shield case wherein said tab has an extended end to be snapped into said slot. According to still another aspect of the invention there is provided a method of making an electrical connector shield case for covering either protuberance or opening of an insulating housing with a plurality of contacts arranged therein, which comprises the steps of (a) punching out a metal sheet with at least one boss and latch means; (b) bending opposite ends of said metal sheet upwright; and (c) bending said opposite ends inward to form a cylindrical shield case. Other features and advantages of the present invention will be apparent from the following description of the preferred embodiments with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of an electrical connector shield case embodying the present invention. FIG. 2 is an exploded perspective view of part of the electrical connector employing the shield case of FIG. 1. FIGS. 3A-3F illustrate a method of making the shield case of FIG. 1. FIG. 4 is an exploded perspective view of part of an electrical connector employing another embodiment of the shield case according to the invention. FIG. 5 an exploded perspective view of part of an electrical connector employing still another embodiment of the shield case according to the invention. FIGS. 6A-6B are perspective views of a shield case of the prior art. FIGS. 7A-7F illustrate a method of making the shield case of FIG. 6A according to the prior art. DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring now to FIG. 1 there is shown an electrical connector shield case 100 formed according to the present invention so as to define a space 101 having a trapezoidal section. Its parallel major sides 102 and 103 have bosses 104 and 105, respectively, projecting outward. The major side 102 has at its center a pair of mating portions 106 each with an engaging tab 107 which is extended upward. The major side 102 has along its upper edge a pair of enclosing flanges 108 curved outward and then upward. The major side 103 has along its upper edge an enclosing flange 109 curved outward and then upward. The major side 102 has a latch claw 112 between the enclosing flange 108 and the minor side 110 and a latch claw 113 between the enclosing flange 108 and the minor side 111, while the major side 103 has a latch claw 114 between the enclosing flange 109 and the minor side 110 and a latch claw 115 between the enclosing flange 109 and the minor side 111. The major side 102 has a pair of stopper flanges 116 bent inward along its lower edge, while the major side 103 has an stopper flange 117 bent inward along its lower edge. Referring to FIG. 2 there is shown a plug connector 200 having an insulating housing 201 to which the shield case 100 according to the present invention is applied. The insulating housing 201 has a fitting protuberance 202 having a section similar to that of the space 101 and a base portion 203 integral with the fitting protuberance 202 and having a section greater than that of the protuberance. The base portion 203 has a pair of flanges 206 and 207 on its upper and lowr major sides 204 and 205. The flange 206 has a pair of notches 208 and 209 with which the respective claws 112 and 113 and the flange 207 has a pair of notches (not shown) for the claws 114 and 115. The fitting protuberance 202 is adapted to fit into the enclosure defined by the major sides 102 and 103 and the minor sides 110 and 111 of the shield case 100. The front edges of the fitting protuberance 202 engage with the stop flanges 116, 117. The engaging tab 107 is inserted into a slot (not shown) opened through the flange 206 into the base 203. An end 212 of a female contact (not shown) is projected from the rear side 210 of the base 203 and is connected to a core wire 301 of a shield cable 300. A pair of metal plug case halves 213 and 214 are adapted to house the base 203 and the flange 206 in such a manner that the fitting protuberance 202 may be projected from the case. Portions of the plug case inside adjacent to the flange 206 are brought into contact with the enclosing flanges 108 and 109 and the latch claws 112 to 115 thereby to secure shielding function. The case halves 213 and 214 have cutouts 215 and 216, respectively, to allow insertion of the shield cable 300. The insides of the cutouts 215 and 216 are brought into contact with a conductive tape 303 wrapped around a folded shield sheat 302 to secure shielding function. The above plug connector is adapted to insert into a receptacle connector 400 with a receptacle case 401 secured to a circuit board 500 with a screw 501. The receptacle case has an opening 402 for receiving the protuberance 202 of the plug connector 200. Within the opening 402 there are provided a plurality of male contacts 403 so that they may come into contact with the female contacts placed in the holes of the other face of the protuberance 202. The base of each male contact 403 is inserted into a hole (not shown) of an insulating housing 404 within the receptacle case 401 and connected to a appropriate element (not shown) on a circuit board 500. When the plug connector 200 is inserted into the opening 402, the bosses 104 and 105 of the shield case 100 are brought into contact with the inside 405 of the opening to provide shielding function. FIGS. 3A-3F illustrate a method of making the electrical connector shield case according to the invention. A metal sheet 10 with dimensions corresponding to those of a final product or electrical connector shield case 100 is placed on the lower die 20 with depressions 21 and other depressions (not shown) provided at the positions corresponding to the bosses 104 and 105 and the parts to be cut off, respectively, and the upper die 30 with projections 31 and other projections (not shown) provided at the positions corresponding to the bosses 104 and 105 and the parts to be cut off, respectively, is pressed against the lower die 20 (FIGS. 3A and 3B) to form bosses 104 and 105, tab 107, enclosing flanges 108 and 109, latch claws 112, 113, 114, and 115, and stop flanges 116 and 117 (FIG. 3C). The metal sheet 10 is then placed on the die 40 with a depression 41, and the upper die 50 with a projection 51 having a shape corresponding to the depression 41 is pressed down (FIG. 3D). The core die 60 with a shape substantially identical with that of the space 101 is then placed on the central part of the metal sheet 10, and the opposite ends of the sheet 10 are pressed in the directions of arrows (FIG. 3E). After the pressing, the core die 60 is removed to provide an electrical connector shield case 100 made according to the invention (FIG. 3F). The above electrical connector shield case 100 has latch claws 112 through 115 to engage the notches 208 and 209 of the insulating housing 201, but these claws 112 through 115 and notches 208 and 209 may be eliminated as shown in FIG. 4. This electrical connector shield case 100A has an engaging tab 107A with an extended end 128A and an engaging tab 127A with an extended end 128A provided at the center of the enclosing flange 109A. The shield case 100A is applied to a plug connector 201A with flanges 206A and 207A each having engaging slot 217A. Each of the engaging tabs 107A and 127A is snapped into the engaging slot 217A so that its extended end 128A may rest on the flange. The other structures are identical with those of FIGS. 1 through 3, and their description will be omitted. The above electrical connector shield case 100 or 100A is fitted over the protuberance 202 of a plug connector and is brought into contact with the shield member, such as the metal case, of a receptacle connector to secure shielding function when it is inserted into the receptacle connector. This sytem, however, requires that the receptacle case be made of conductive metal, increasing the number of parts. Thus, the receptacle case 401 of a receptacle connector 400 is made of insulating material, with a shield case placed within its opening 402 as described below with reference to FIG. 5. In FIG. 5, a shield case 403B defines a space 406B with a trapezoidal cross section substantially identical with that of an opening 402B and has bosses 409B and 410B on the insides of its major sides 407B and 408B. The major sides 407B and 408B have engaging tabs 411B and 412B, respectively, on their rear edges. The engaging tab 411B has an extended end 413B. The major sides 407B and 408B have flanges 414B and 415B, respectively, along their front edges. The receptacle case 401B has a number of male contacts 416B arranged on its base part within the opening 402B and, at the central parts on opposite major insides, a snap slot 418B into which the snap tab 411B is snapped and a slot 419B into which the tab 412B is inserted. After inserted, the free end of the tab 412B is bent and connected to a circuit board 500B to secure shield function. The edges of the opening 402B have cutouts 421B and 422B for receiving the flanges 414B and 415B, respectively. The shield case for covering the protuberance of a plug connector to be inserted into the opening 402B of this receptacle requires no bosses on its surface to secure shielding function because of the presence of bosses 409B and 410B on the shield case 403B. Alternatively, these bosses 409B and 410B may be eliminated from the shield case 403B by providing bosses on the shield case of a plug connector. The other structures of the plug connector are similar to those of FIGS. 1 through 4, and their description will be omitted. As has been described above, according to the invention, a metal sheet may be punched out and bent to form a cylindrical electric connector shield case to eliminate the drawing press process and the metal sheet deformation in connection with the process, thus increasing the material utility. In addition, since no drawing press is used, it is unnecessary to use any extensible, soft material, thus allowing the formation of resilient bosses and eliminating the deformation caused by the excess external force otherwise required. Moreover, the wall thickness is even in every section, giving high precision. The direction of a protuberance is selectable, too. Although the preferred embodiments of the present invention have been described above, other embodiments and modifications which would be apparent to one having ordinary skill in the art are intended to be covered by the spirit and scope of the appended claims.

4y

This application claims priority on Japanese Patent Application No. 2007-048787 filed on Feb. 28, 2007, and on Japanese Patent Application No. 2008-005502 filed on Jan. 15, 2008, both in the Japanese Patent Office, the entire contents of which applications are hereby incorporated by reference. TECHNICAL FIELD The present invention relates to a friction drive actuator and more particularly to a friction drive actuator for causing a vibration member to make pressure contact with a sliding member to generate a relative movement. BACKGROUND Conventionally, use of a friction drive actuator for various moving devices has been tried. The friction drive actuator is generally comprised of a vibration member having a piezoelectric element which is an electromechanical energy conversion element and a sliding member for making contact with the vibration member in a pressurized state. The friction drive actuator is an actuator in which a relative movement between the vibration member and the sliding member in pressure contact with the vibration member is caused by an elliptical vibration (herein after, including a circular vibration) of a part of the vibration member, the elliptical vibration which is generated by inputting a drive signal into the piezoelectric element to expand and contract it. The friction drive actuator is compact and excellent in silence, so that it is used as a drive mechanism for an electronic device such as an electronic camera, and in recent years, its applications have been spread more, and use thereof in a drive mechanism of a recording/reproducing head of an information recording apparatus such as a HDD and a DVD has been variously examined. For example, there is known a vibration wave linear motor (a friction drive actuator) in which a vibration member is pressurized and held between two cylindrical guide shafts (sliding members), and due to an elliptical vibration generated in the drive contact portion of the vibration member, the vibration member and guide shafts make a relative movement in the axial direction (for example, refer to Unexamined Japanese Patent Application Publication No. 2005-57838). Here, the schematic constitution of the vibration wave linear motor disclosed in Unexamined Japanese Patent Application Publication No. 2005-57838 will be explained by referring to FIGS. 10 a , 10 b . FIG. 10 a is a front sectional view of a vibration wave linear motor 46 , and FIG. 10 b is a cross sectional view along the line D-D′ in FIG. 10 a. On each of the upper and lower surfaces of a vibrator body 75 , provided is a connection type drive contact portion 93 in which a flat portion 92 and a drive contact portion 76 are unified with each other. Two upper and lower guide shafts 77 ( 77 - 1 , 77 - 2 ) in contact with recessed portions 76 a of the connection type drive contact portions 93 are supported by upright members 78 - 2 of support members 78 . The lower guide shaft 77 - 2 is pressed upwardly by a spiral spring 83 , thus a vibrator 70 is pressurized and held between the two guide shafts 77 . When AC voltages different in phase are applied to the vibrator body 75 , the vibrator body 75 generates a vibration wave, and an elliptical rotation vibration is generated in the drive contact portions 76 . By the elliptical rotation vibration, the vibrator 70 moves relatively to the two guide shafts 77 and support members 78 in the axial direction. By use of such a constitution, one part thereof is fixed, and the other part is connected to a driven member, thus the driven member can be driven to move. Further, there is known a fine drive device (a friction drive actuator) for swinging a head arm (a sliding member) having a recording/reproducing head around a rotary shaft inserted through a rotation hole formed in the head arm, the drive device which is driven by an elliptical vibration generated in a vibration member in pressure contact with the head arm (for example, refer to Unexamined Japanese Patent Application Publication No. 2000-224876). Further, there is known a rotary type ultrasonic actuator (a friction drive actuator) for rotating a rotor (a sliding member) born by ball bearings by a vibration member (for example, refer to Unexamined Japanese Patent Application Publication No. H06-78570). Further, there is known an information recording/reproducing head drive device (a friction drive actuator) for swinging a head arm (a sliding member) around a V-shaped fulcrum formed in the head arm and supported by a wedge type support member by an elliptical vibration generated in a vibration member in pressure contact with the head arm (for example, refer to Unexamined Japanese Patent Application Publication No. 2001-222869). On the other hand, in the information recording apparatus such as a HDD and a DVD, with the progress of higher recording density, the head drive mechanism is required to realize highly precise positioning of the head to the target position of a recording medium in submicron. Further, in correspondence with miniaturization and lower price of the information recording apparatus, further miniaturization and lower price are required for the drive mechanism. In the vibration wave linear motor disclosed in Unexamined Japanese Patent Application Publication No. 2005-57838, as shown in FIG. 10 b , the contact surfaces between the guide shafts 77 ( 77 - 1 , 77 - 2 ) and the drive contact portions 76 are formed in a cylindrical shape with the same radius. However, when joining the two, unless the radii of the recessed portions 76 a of the drive contact portions 76 are made larger than the radii of the guide shafts 77 ( 77 - 1 , 77 - 2 ), and gaps are formed between the two, the two cannot be joined. Therefore, even if the two are processed highly precisely, gaps of microns are generated, and backlash is caused. Further, the guide shaft 77 - 2 is supported by a bearing slotted hole 81 formed in the upright member 78 - 2 and is pressed up by the spiral spring 83 . However, the support member is required to have a fitting backlash of microns, and an inclination of the vibrator 70 with respect to the guide shaft 77 , which is equivalent to the fitting backlash, is generated and the relative position between the vibrator 70 and the guide shaft 77 fluctuates. Therefore, in the vibration wave linear motor having such a constitution, due to various types of backlash of microns generated between the vibrator 70 and the guide shaft 77 , it is difficult to set highly precisely the relative position between the two in microns which is required for the information recording apparatus. Further, in the fine drive device disclosed in Unexamined Japanese Patent Application Publication No. 2000-224876, although the mechanism constitution is not described in detail, the head arm has a bearing mechanism of the rotary shaft, so that it can be inferred easily that backlash is caused in the bearing section. Further, the vibration member is structured so as to incline also in a direction other than the pressing direction, and for example, the head arm may rotate in a slightly twisted direction with respect to the rotary shaft. Therefore, there is a possibility that the head section provided at the end of the head arm may collide with the recording surface of the disk. Further, the constitution having no bearing mechanism is disclosed, though even in these constitutions, by the out-of-roundness and abrasion condition of the guide member and a shift of the shaft center due to a dent caused by an impact load, it may be considered that the positioning is affected greatly. Further, in the rotary type ultrasonic actuator disclosed in Unexamined Japanese Patent Application Publication No. H06-78570, the members such as the ball bearings for bearing the rotor are used, so that backlash between the balls and the inner and outer walls cannot be avoided. The backlash component in the direction of the rotary shaft is biased, though the backlash component in the radial direction cannot be biased. These gaps are ones in microns and influence greatly the positioning. Further, at time of drive start of the vibration member, the gaps are first biased and then the drive in a desired direction is started, so that a problem arises that the startup characteristic is influenced. Further, when a highly rigid load support member is structured by such a mechanism, there is a possibility that complication and high price of the device due to enlargement of the apparatus and an increase in the mechanical parts may be caused. Further, in the information recording/reproducing head drive apparatus disclosed in Unexamined Japanese Patent Application Publication No. 2001-222869, due to the pressure contact of the vibration member, the compression pressure to the V-shaped fulcrum by the wedge type support member is increased, thus there is a possibility that the fulcrum may be abraded. As a result, the position of the head mounted on the end of the arm is changed. SUMMARY In view of the forgoing problems, an object of the present invention is to provide a friction drive actuator for realizing highly precise positioning without causing complication and high price. In view of forgoing, one embodiment according to one aspect of the present invention is a friction drive actuator, comprising: a vibration member which is configured to be driven to vibrate by expansion and contraction of a piezoelectric displacement portion which is included in the vibration member and driven by a driving signal; a sliding member which is in contact with the vibration member and is driven by the vibration member in a first direction with respect to the vibration member; a pressing member which causes the vibration member and the sliding member to come into a pressure contact therebetween; and a control member which is provided on each of the vibration member and the sliding member at a contact portion therebetween for controlling a relative movement of the sliding member with respect to the vibration member in a direction perpendicular to the first direction and parallel to a surface of the sliding member when the vibration member and the sliding member are pressedly contacted with each other by the pressing member. According to another aspect of the present invention, another embodiment is a friction drive actuator, comprising: a vibration member which is configured to be driven to vibrate by expansion and contraction of a piezoelectric displacement portion which is included in the vibration member and driven by a driving signal; a sliding member which is formed to be circular, disposed in pressure contact with the vibration member at an inner circumferential surface of the sliding member so as to be elastically deformed, and rotates in a first direction with respect to the vibration member when driven by the vibration member; and a control portion which is provided on each of the vibration member and the sliding member at a contact portion therebetween for controlling a relative movement of the sliding member with respect to the vibration member in a direction perpendicular to the first direction and parallel to a surface of the sliding member. BRIEF DESCRIPTION OF THE DRAWINGS FIGS. 1 a , 1 b are entire schematic views of a friction drive actuator of Embodiment 1 of the present invention, FIGS. 2 a , 2 b , 2 c are external views showing the constitution of a vibration member of Embodiment 1, FIGS. 3 a , 3 b , 3 c are drawings showing the situation of a modification of the vibration member in the resonance mode of Embodiment 1, FIGS. 4 a , 4 b are entire schematic views of a friction drive actuator of Modification 1 of Embodiment 1, FIGS. 5 a , 5 b are entire schematic views of a friction drive actuator of Modification 2 of Embodiment 1, FIGS. 6 a , 6 b , 6 c are entire schematic views of the friction drive actuator of Embodiment 2 of the present invention, FIGS. 7 a , 7 b , 7 c are external views showing the constitution of the vibration member of Embodiment 2, FIGS. 8 a , 8 b are entire schematic views of a friction drive actuator of Modification 1 of Embodiment 2, FIGS. 9 a , 9 b , 9 c are external views showing the constitution of the vibration member of Modification 1 of Embodiment 2, and FIGS. 10 a , 10 b are entire schematic views of a conventional friction drive actuator. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the friction drive actuator relating to the present invention will be described with reference to the accompanying drawings. Further, although the present invention will be described on the basis of the embodiments drawn, the present invention is not limited there. Embodiment 1 Firstly, the constitution of the friction drive actuator of Embodiment 1 will be described by referring to FIGS. 1 a , 1 b . FIG. 1 a is a front view showing the outline of the entire constitution of a friction drive actuator 1 and FIG. 1 b is a side view thereof. The friction drive actuator 1 , as shown in FIG. 1 a , includes a vibration member 10 , a sliding member 20 , and a pressing member 30 . In the friction drive actuator 1 , a part of the vibration member 10 is made to move so as to make an elliptical orbit (including a circular orbit), that is, make an elliptical vibration (including a circular vibration) by inputting a drive signal into the vibration member 10 having a piezoelectric displacement element 101 , which will be described later, comprised of an electromechanical energy conversion element so as to permit the vibration member 10 to expand and contract. By doing this, the friction drive actuator permits the vibration member 10 and the sliding member 2 in contact therewith in the pressurized state to make a relative movement by frictional force. The sliding member 20 is permitted to make pressure contact with the vibration member 10 by the pressing member 30 comprised of a coil spring 301 , a roller 302 , and a roller rotary shaft 303 . When the vibration member 10 is driven to make an elliptical vibration, the sliding member 20 is moved by the frictional force. When the rotational direction of the elliptical vibration is clockwise, the sliding member 20 moves to the right, and when it is counterclockwise, the sliding member 20 moves to the left. The sliding member 20 is an elongated part with an almost rectangular cross section and made of a metal such as stainless steel which is inexpensive and easy to process. The surface thereof, to prevent abrasion with the vibration member 10 , is subject to the surface hardening treatment such as tempering or nitriding treatment. Ceramic coating such as CrN or TiCN may be applied. Further, by use of ceramics such as alumina or zirconia, the abrasion resistance can be improved more. Further, to prevent abrasion with the vibration member 10 , it is preferable that the surface of the contact portion of the sliding member 20 is smooth. The constitution of the vibration member 10 is shown in FIGS. 2 a , 2 b , 2 c . FIG. 2 a is a front view of the vibration member 10 , and FIG. 2 b is a side view thereof, and FIG. 2 c is a plan view thereof. The vibration member 10 , as shown in FIG. 2 a , includes the piezoelectric displacement portion 101 and a contact portion 102 . The piezoelectric displacement portion 101 has a rectangular shape comprised of the electromechanical energy conversion element such as a piezoelectric element and performs a resonance in the primary longitudinal (expansion and contraction) vibration mode and secondary bending vibration mode which will be described later. The piezoelectric displacement portion 101 is comprised of four displacement portions 101 a , 101 b , 101 c , and 101 d , and an inner electrode not shown is divided in a predetermined shape for each displacement portion. A predetermined voltage waveform is impressed to these electrodes, thus to hemispherical projections 102 a and 102 b formed on the concerned contact portion 102 , an elliptical vibration is excited. Further, the shape of the vibration member 10 and the resonance modes used for driving are not limited to thereto, and an ordinary stationary wave vibration member whose drive force can be taken out from a plurality of places is usable. Further, as an electromechanical energy conversion element (hereinafter, may be referred to as a displacement element), a laminated piezoelectric element made by alternately laminating a plurality of ceramic thin plates, such as a PZT, showing the piezoelectric characteristic and inner electrodes may be used, or a combination of a single layer of piezoelectric element and a metallic elastic body may be used. In the former case, by adding the displacement of each ceramic thin plate (a piezoelectric element of a single layer), the displacement of whole the displacement element is increased. In the latter case, by resonating the elastic body using the piezoelectric element as a drive source, a large displacement can be obtained. As a material of the contact portion 102 , a preferable material is an ultra hard material which is made of tungsten carbide (WC) as a main material and has a high stable friction coefficient and an excellent abrasion resistance. Further, hard ceramics such as alumina or zirconia may be used, or a ferrous material the surface of which is hardened by the surface treatment such as heat treatment or nitriding treatment may be used. Here, the elliptical vibration excited in the vibration member 10 having such a constitution will be described by referring to FIGS. 3 a , 3 b , 3 c . The vibration member 10 is resonantly driven. FIGS. 3 a , 3 b , 3 c show the appearance of the deformation of the vibration member 10 in the intrinsic mode used for the resonance drive, and FIG. 3 a is a drawing showing the appearance of the vibration member 10 when not driven, and FIG. 3 b is a drawing showing the appearance of the deformation in the primary longitudinal (expansion and contraction) vibration mode, and FIG. 3 c is a drawing showing the appearance of the deformation in the secondary bending vibration mode. In the primary longitudinal vibration mode, as shown in FIG. 3 b , an expansion and contraction vibration is performed with a central part F 1 of the vibration member 10 as a node, and the projections 102 a and 102 b are displaced in the Y direction (longitudinal direction). In the secondary bending vibration mode, as shown in FIG. 3 c , a secondary bending modification is performed with F 2 as a node, and the ends of the projections 102 a and 102 b are displaced in the P direction. Further, the appearance of the deformation of the vibration member 10 shown in FIGS. 3 b and 3 c are exaggeratedly drawn in displacement amount for the purpose of explanation in the respective modes. The primary longitudinal vibration mode is driven by impressing drive signals in the same phase at their resonance frequencies to the four displacement portions 101 a , 101 b , 101 c , and 101 d . The secondary bending vibration mode is drive by impressing a drive signal 1 in the same phase to the displacement portions 101 a and 101 d and by impressing a drive signal 2 having a predetermined phase difference from the phase of the drive signal 1 to the displacement portions 101 b and 101 c at their resonance frequencies. The shape of the vibration member 10 is formed so as to set both the resonance frequencies in the primary longitudinal vibration mode and secondary bending vibration mode within a predetermined range, and the vibration member 10 is driven with the two modes almost synchronized with each other, and an elliptical vibration D is thus excited in the projections 102 a and 102 b , as shown in FIG. 3 a . When the projections 102 a and 102 b are driven so as to make an elliptical orbit, the projections 102 a and 102 b make contact with the sliding member 20 in a certain range, and the sliding member 20 is driven in a predetermined direction by the frictional force acting between the projections 102 a and 102 b and the sliding member 20 . Further, when the phase shift direction of the drive signals is reversed, the rotational direction of the elliptical orbit of the projections 102 a and 102 b is reversed, and the moving direction of the sliding member 20 is reversed. In the friction drive actuator 1 of this embodiment having such a constitution, the change in the relative position between the vibration member 10 and the sliding member 20 is controlled so as to uniquely set the relative position in a direction except a predetermined relative movement direction which is the first direction of the present invention. Hereinafter, the details will be explained. As shown in FIGS. 1 a and 1 b , the vibration member 10 is engaged to a shaft 40 a provided on a fixing stand 40 corresponding to the base of the present invention through a hole 101 h formed in the neighborhood of the node F 2 of the secondary bending vibration and is positioned and fixed in the XY plane of the fixing stand 40 . The shaft 40 a is preferably engaged to the hole 101 h by close fit to eliminate backlash. Further, to prevent the vibration member 40 from vibrating laterally (in the X direction) of the fixing stand 40 , the vibration member 10 is engaged to a support member 40 b provided on the fixing stand 40 for supporting the neighborhood of both ends of the node F 1 of the vibration member 10 in the primary longitudinal vibration mode. Further, although there needs to be a gap between the vibration member 10 and fixing stand 40 when they get engaged to each other, they are fixed by an adhesive to eliminate backlash due to the gap. Further, when the adhesion is difficult, the vibration member 10 is pressed by a plate spring 41 against the fixing stand 40 to eliminate backlash also in the Z direction. Further, the fixing of the vibration member 10 is preferably executed in the neighborhood of the node of the vibration as mentioned above so as to prevent the vibration member 10 from disturbing the vibration. Further, power is supplied to the vibration member 10 by using a flexible printed circuit board or a lead wire. As shown in FIGS. 1 a and 1 b , the sliding member 20 is an elongated part having an almost rectangular cross section, and a groove portion 20 c including a V-shaped elongated groove 20 a is formed in the X direction (a predetermined relative movement direction) on the opposite surface to the vibration member 10 . The two hemispherical projections 102 a , which are provided on the contact portion 102 of the vibration member 10 and correspond to the projections of the present invention, make contact with the V-shaped elongated groove 20 a . The angle of the V-shaped portion of the V-shaped elongated groove 20 a is preferably 90°, though it is not limited to it and is preferably from 60° to 120° or so. When the angle of the V-shaped portion is excessively small, the engagement of the V-shaped elongated groove 20 a to the projections 102 a becomes shallow, and the V-shaped elongated groove 20 a makes contact with the projections 102 a in the neighborhood of the edge thereof, thus the engagement is easy to be disengaged. On the other hand, when the angle of the V-shaped portion is excessively large, the contacts of the side wall of the V-shaped elongated groove 20 a with the projections 102 a get close each other, and the angle holding the contacts becomes smaller, so that the effect of positioning is lowered. Further, on the surface of the sliding member 20 where the V-shaped elongated groove 20 a is formed, a belt-shaped flat stripe portion such as a flat stripe portion 20 b for controlling the swing of the sliding member 20 around the X-axis is provided in a belt shape in parallel to the V-shaped elongated groove 20 a . The projection 102 b which is provided on the contact portion 102 of the vibration member 10 and corresponds to the projection of the present invention makes contact with the flat stripe portion 20 b. It is preferable that the surfaces of the V-shaped elongated groove 20 a and flat stripe portion 20 b have smooth surfaces having small surface roughness, and the flatness thereof is highly precise. Further, as the distance between the V-shaped elongated groove 20 a and the flat stripe portion 20 b becomes longer, the control effect for the swing of the sliding member 20 around the X-axis is increased. Further, the projections 102 a and 102 b , V-shaped elongated groove 20 a , and flat stripe portion 20 b correspond to the control member of the present invention. To keep the sliding member 20 and vibration member 10 in the prescribed contact state, the pressing member 30 permits the sliding member 20 and vibration member 10 to be in pressure contact with each other. The pressing force of the pressing member 30 is transferred by the roller 302 , and the coil spring 301 is provided between the roller rotary shaft 303 for bearing the roller 302 and a fixing member 50 . The working point of the pressing member 30 to the sliding member 20 is the contact portion between the roller 302 and the sliding member 20 , and it is preferable that this contact portion is located almost at the central part of the area, viewed in the Y direction, surrounded by all the contact points between the sliding member 20 and the vibration member 10 , that is, the projections 102 a and 102 b , V-shaped elongated groove 20 a , and flat stripe portion 20 b . When the working point is outside the concerned area, the posture of the contact portion is easy to change due to a disturbance. As mentioned above, the relative position between the sliding member 20 and the vibration member 10 is controlled by the four contact points between the V-shaped elongated groove 20 a of the sliding member 20 and the two projections 102 a of the vibration member 10 , so that the changes in the Y direction and Z direction, except the movement in the X direction (the first direction of the invention, or predetermined relative movement direction), are controlled. Further, the pressing force by the pressing member 30 permits the projection 102 b of the vibration member 10 and the flat stripe portion 20 b of the sliding member 20 to make pressure contact with each other, so that the swing of the sliding member 20 around the X-axis is controlled. As a result, the relative position between the sliding member 20 and the vibration member 10 is set uniquely except the movement in the X direction (the first direction, or predetermined relative movement direction). As mentioned above, in the friction drive actuator 1 of Embodiment 1 of the present invention, by the pressing member 30 and control member (the two projections 102 a and 102 b , groove portion 20 c , flat stripe portion 20 b ), the relative position between the vibration member 10 and the sliding member 20 is set uniquely except the predetermined relative movement direction. Since the relative position between the vibration member 10 and the sliding member 20 is set uniquely, the vibration member 10 is positioned, for example, to the cabinet of frame of the apparatus via the fixing stand 40 , thus the position of the sliding member 20 is set also at a predetermined position. As a result, a driven member such as the recording/reproducing head to be attached to the sliding member 20 can be positioned with high precision. Further, there is no backlash at the contact position between the vibration member 10 and the sliding member 20 , so that from immediately after start of driving, the sliding member 20 is moved in a desired direction, and a drive mechanism having a rapid start response can be structured. Further, the conventional bearing members are not necessary, and the members concerned in driving are decreased, so that the designs intrinsic to the vibration drive such as keeping the resonance frequencies of these members away from the drive frequency are decreased, thus the apparatus can be designed easily. Further, since the bearing members are not necessary, enlargement and complication of the device are not caused, and the rigidity of the friction drive actuator 1 can be improved. Therefore, the frequency band under the servo control can be shifted toward the high frequency side, and the controllability can be enhanced. Further, the contact points of by the control member between the vibration member 10 and the sliding member 20 all transfer the drive force, so that even if the friction coefficient at one contact point is changed due to local changes in the surface condition, the friction coefficients including the other contact points are averaged, thus stable driving force can be obtained. Further, compared with the conventional friction drive actuator, the number of components is decreased, so that the device can be miniaturized. Modification 1 of Embodiment 1 The constitution of the friction drive actuator 1 according to Modification 1 of Embodiment 1 is shown in FIGS. 4 a , 4 b . FIG. 4 a is a front view showing the outline of the entire constitution of the friction drive actuator 1 and FIG. 4 b is a side view thereof. In the friction drive actuator 1 according to Modification 1, as shown in FIGS. 4 a and 4 b , two semicylindrical convex rails 21 a and 21 b corresponding to the convex rails of the present invention are provided in parallel in the X direction (the first direction, or the predetermined relative movement direction) on the surface, of a sliding member 21 , opposite to a vibration member 11 . On the other hand, in the vibration member 11 , a groove portion 112 c having two V-shaped grooves 112 a in contact with the convex rail 21 a are provided with a predetermined interval in the X direction (the first direction, or the predetermined relative movement direction) Further, a flat stripe portion 112 b in contact with the convex rail 21 b is provided in a belt shape in parallel with the direction connecting the two V-shaped grooves 112 a. Further, the length of the V-shaped grooves 112 a in the X direction (the first direction, or the predetermined relative movement direction) is preferably shorter. When the length is longer, each contact between the V-shaped grooves 112 a and the convex rail enter the line contact state, so that the relative movement of the sliding member 21 in the X direction (the first direction, the predetermined relative movement direction) may be affected depending on the processing precision. The relative position between the sliding member 21 and the vibration member 11 is controlled at the four contact points between the convex rail 21 a of the sliding member 21 and the two V-shaped grooves 112 a of the vibration member 11 , so that the changes in the Y direction and Z direction except the movement in the X direction (the predetermined relative movement direction) are controlled. Further, the pressing force by the pressing member 30 permits the convex rail 21 b of the sliding member 21 and the flat stripe portion 112 b of the vibration member 11 to make pressure contact with each other, so that the swing of the sliding member 21 around the X-axis is controlled. As a result, the relative position between the sliding member 21 and the vibration member 11 is set uniquely except the movement in the X direction (the first direction, or the predetermined relative movement direction) and the same effect as that of Embodiment 1 can be obtained. Modification 2 of Embodiment 1 The constitution of the friction drive actuator 1 according to Modification 2 of Embodiment 1 is shown in FIGS. 5 a , 5 b . FIG. 5 a is a front view showing the outline of the entire constitution of the friction drive actuator 1 , and FIG. 5 b is a side view thereof. The friction drive actuator 1 according to Modification 2, as shown in FIGS. 5 a and 5 b , has two vibration members similar to the vibration member 10 of Embodiment 1 which is described by referring to FIGS. 1 a , 1 b (vibration members 10 - 1 and 10 - 2 ). One vibration member 10 - 1 is positioned, similarly to Embodiment 1, for example, on the cabinet or frame of the device via a fixing stand 40 - 1 . A pressing member 31 , in replacement of the roller 302 of Embodiment 1, has the other vibration member 10 - 2 and permits the sliding member 20 to make pressure contact with the vibration member 10 - 1 by using the concerned vibration member 10 - 2 . In the friction drive actuator 1 having such a constitution, the two vibration members (the vibration members 10 - 1 and 10 - 2 ) are caused to perform an elliptical vibration, thus driving force two times that of Embodiment 1 can be obtained. Further, it is a preferable constitution that the fixed vibration member 10 - 1 controls the relative position to the sliding member 20 , and the vibration member 10 - 2 performs only driving and pressurization but does not control the relative position. Embodiment 2 The constitution of the friction drive actuator 1 according to Embodiment 2 will be explained by referring to FIGS. 6 a , 6 b , 6 c . FIG. 6 a is a front view showing the outline of the entire constitution of the friction drive actuator 1 , and FIG. 6 b is a cross sectional view along the line A-A′ shown in FIG. 6 a , and FIG. 6 c is a cross sectional view along the line A-B shown in FIG. 6 a. The friction drive actuator 1 , as shown in FIG. 6 a , includes a vibration member 12 , a sliding member 22 , and the pressing member 30 . In the friction drive actuator 1 according to Embodiment 1, the vibration member 10 and sliding member 20 make a straight relative movement, while in Embodiment 2, the circular ring-shaped sliding member 22 and the vibration member 12 arranged therein make a relative rotation. The sliding member 22 , as shown in FIG. 6 a , is formed in a circular ring shape, and as shown in FIGS. 6 b and 6 c , a groove portion 22 c having a V-shaped elongated groove 22 a is formed in a ring shape in a swing direction Q (a first direction of the present invention, or a predetermined relative movement direction) on the surface thereof facing the vibration member 12 . Further, on the surface where the V-shaped elongated groove 22 a of the sliding member 22 is formed, a flat stripe portion 22 b for controlling the swing of the sliding member 22 around the X-axis is provided in a belt shape in parallel with the V-shaped elongated groove 22 a. On the other hand, the surface of the vibration member 12 facing the sliding member 22 , as shown in FIGS. 7 a , 7 b , 7 c , is formed in a circular arc shape along the inner peripheral surface of the sliding member 22 . On the vibration member 12 , two hemispherical projections 122 a in contact with the V-shaped elongated groove 22 a are provided with a predetermined interval in the swing direction Q (the predetermined relative movement direction) Further, a projection 122 b is provided in contact with the flat stripe portion 20 b . Further, it should be noted that FIG. 7 a is a front view of the vibration member 12 , and FIG. 7 b is a side view thereof, and FIG. 7 c is a plan view thereof. The relative position between the sliding member 22 and the vibration member 12 is controlled by the four contact points between the V-shaped elongated groove 22 a of the sliding member 22 and the two projections 122 a of the vibration member 12 , so that the changes in the Y direction and Z direction are controlled except the movement in the rotating direction Q (the first direction, or the predetermined relative movement direction). Further, the pressing force by the pressing member 30 causes the projection 122 b of the vibration member 12 and the flat stripe portion 22 b of the sliding member 22 to make pressure contact with each other, so that the rotation of the sliding member 22 around the X-axis is controlled. As a result, the relative position between the sliding member 22 and the vibration member 12 is set uniquely except the movement in the rotating direction Q (the first direction, or the predetermined relative movement direction) and the same effect as that of Embodiment 1 can be obtained. Modification 1 of Embodiment 2 The constitution of the friction drive actuator 1 according to Modification 1 of Embodiment 2 is shown in FIGS. 8 a , 8 b . FIG. 8 a is a front view showing the outline of the entire constitution of the friction drive actuator 1 , and FIG. 8 b is a cross sectional view along the line A-B shown in FIG. 8 a. The friction drive actuator 1 according to Modification 1, as shown in FIG. 8 a , includes a vibration member 12 and sliding member 22 , and similarly to Embodiment 2, the circular ring-shaped sliding member 22 rotates relative to the vibration member 12 arranged therein. In the friction drive actuator 1 according to Modification 1, the sliding member 22 itself has a pressing function instead of having a pressing member 30 comprised of a coil spring 301 , roller 302 , and roller rotary shaft 303 which are equipped in Embodiment 2. In the sliding member 22 , before assembly with the vibration member 12 , the diameter (inside diameter) thereof is set smaller than the length of the vibration member 12 , and when it is assembled with the vibration member 12 , the sliding member 22 is deformed by the vibration member 12 so that the diameter thereof is increased (in an elliptical shape), and on each contact portion between the vibration member 12 and the sliding member 22 , the restoring force due to the elastic deformation of the sliding member 22 acts as pressing force. By the pressing force, the movement in the radial direction of the sliding member 22 with respect to the vibration member 12 is controlled without any backlash. Further, the contact between the sliding member 22 and the vibration member 12 is limited at three portions, instead of all the circumferential area, so as to provide non-contact portions free of restriction by the vibration member 12 . Compared with the case that all the circumferential area is in contact with the vibration member 12 , the elastic deformation of the sliding member 22 is easy, so that the sliding member 22 is charged by the contact portions and the spring constant, when assuming the pressing force as one caused by the spring, is made smaller, compared with the case that all the circumferential area is in contact. In this arrangement, even if there are manufacturing errors in the dimensions of the vibration member 12 or sliding member 22 , changes in the pressing force with respect to the error amounts is limited small. Further, due to temperature changes, even if dimensional changes are caused in the vibration member 12 and sliding member 22 , changes in the pressing force is limited small, since the spring constant is small, thus the pressing force is stabilized. This arrangement reduces the error sensitivity of the pressing force with respect to the change of dimension, consequently, the drive performance is stabilized. Further, the pressing force is generated by the elastic deformation of the sliding member 22 itself, so that an external pressing mechanism is not necessary, and it can contribute to simplification and miniaturization of the mechanism. Further, the adjustment step for the pressing force is not necessary, thus the productivity is improved. As shown in FIG. 8 a , the sliding member 22 is formed in a circular ring shape, and on the surface thereof opposite to the vibration member 12 , the V-shaped elongated groove 22 a is formed in a ring shape in the swing direction Q (the first direction, or the predetermined relative movement direction) as shown in FIG. 8 b. On the other hand, the end face of the vibration member 12 opposite to the sliding member 22 is formed in a circular arc shape along the inner peripheral surface of the sliding member 22 as shown in FIG. 9 a . On the side of one of the short sides of the vibration member 12 , the two hemispherical projections 122 a are installed in contact with the V-shaped elongated groove 22 a with a predetermined interval in the swing direction Q (the first direction, or the predetermined relative movement direction). Further, at the center of the other end face, one hemispherical projection 122 a is installed in contact with the V-shaped elongated groove 22 a . Further, FIG. 9 a is a front view of the vibration member 12 , and FIG. 9 b is a side view thereof, and FIG. 9 c is a plan view thereof. The relative position between the sliding member 22 and the vibration member 12 is controlled at the six contact points between the V-shaped elongated groove 22 a provided in a groove portion 22 c of the sliding member 22 and the three projections 122 a of the vibration member 12 , so that the relative position is uniquely set, except the movement in the swing direction Q (the predetermined relative movement direction), and the same effect as that of Embodiment 1 can be obtained. Further, in this embodiment, the V-shaped elongated groove 22 a is installed in the sliding member 22 , and the three hemispherical projections 122 a are installed on the vibration member 12 in contact with the V-shaped elongated groove 22 a , though they may be configured such that three V-shaped grooves are provided on the vibration member 12 and semicircular semicylindrical convex rails are installed on the sliding member 22 in contact with the three V-shaped grooves. Further, the shape of the vibration member 12 is not limited to the rectangle, and it may be configured triangular so as to be in pressure contact with the sliding member 22 at the three apexes of the triangle. Also in this case, the same effect as that of Embodiment 1 can be obtained. According to the embodiments of the present invention, the constitution is made such that there is provided a control member at each of a plurality of contact portions between the vibration member and the sliding member for controlling the relative movement between the vibration member and the sliding member in the direction perpendicular to a desired movement direction when the vibration member and sliding member are in pressure contact with each other by the pressing member. Namely, by the pressing member and the control member, the relative position between the vibration member and the sliding member is uniquely set except in the desired movement direction. Since the relative position between the vibration member and the sliding member can be uniquely set, the position of the sliding member is set at the predetermined position by positioning the vibration member on, for example, the cabinet or frame of the apparatus. As a result, a driven member to be attached to the sliding member such as the recording/reproducing head can be positioned with high precision. Further, in the case of a circular ring shaped sliding member, the constitution is made such that there is provided a control member on each of a plurality of contact portions between the vibration member and the sliding member for controlling the relative movement between the vibration member and the sliding member in the direction perpendicular to a desired movement direction in the state that the circular ring-shaped sliding member is deformed elastically and the inner peripheral surface thereof is in pressure contact with the vibration member. Namely, the sliding member makes pressure contact with the vibration member due to the restoring force of the sliding member which is formed in a circular ring shape and is deformed in the radial direction. The pressing force is generated from the elastic deformation of the sliding member itself, so that an external pressing mechanism is not necessary and it can contribute to simplification and miniaturization of the mechanism. Further, the adjustment step for the pressing force is not necessary, thus the productivity can be improved.

4y

TECHNICAL FIELD The present invention relates generally to reduction of nitrogen oxides in exhaust gas from a diesel engine. More specifically, this invention pertains to treating the NO x content of the exhaust with the separate additions of reformed diesel fuel and ozone before passing the exhaust into contact with a base metal-exchanged zeolite reduction catalyst. BACKGROUND OF THE INVENTION Diesel engines are operated at higher than stoichiometric air to fuel mass ratios for improved fuel economy. Such lean-burning engines produce a hot exhaust with a relatively high content of oxygen and nitrogen oxides (NO x ). The temperature of the exhaust from a warmed up diesel engine is typically in the range of 200° to 400° C. and has a representative composition, by volume, of about 10–17% oxygen, 3% carbon dioxide, 0.1% carbon monoxide, 180 ppm hydrocarbons, 235 ppm NO x and the balance nitrogen and water. These NO x gases, typically comprising nitric oxide (NO) and nitrogen dioxide (NO 2 ), are difficult to reduce to nitrogen (N 2 ) because of the high oxygen (O 2 ) content in the hot exhaust stream. It is, thus, an object of the present invention to provide an improved method of reducing NO x in such gas mixtures. It is a more specific object of the present invention to provide a method of modifying diesel exhaust with reformed diesel fuel before the exhaust is treated with a zeolite type NO x reduction catalyst. SUMMARY OF THE INVENTION This invention provides a method of reducing NO x in a diesel engine exhaust stream using a dual bed reduction reactor containing base metal-exchanged Y zeolite catalysts. In accordance with the method, separate additions of plasma-reformed diesel fuel and ozone are made to the exhaust gas stream at locations upstream of the catalytic reduction reactor. These additions modify the exhaust composition to improve the performance of the NO x reduction catalysts without degrading them. In the present invention, the NO x containing exhaust is ultimately passed into contact with a dual bed catalyst in which the upstream bed is sodium Y zeolite or barium Y zeolite and the downstream bed is copper Y zeolite. These base metal-exchanged Y-type zeolite catalysts will sometimes be referred to in this specification as NaY, BaY or CuY, respectively. The effectiveness of the dual bed catalyst is promoted by prior addition of plasma-reformed diesel fuel to the exhaust gas followed by the addition of ozone. The ozone addition converts NO to NO 2 before the exhaust reaches the reduction catalyst reactor. The reformed diesel fuel assists in the reduction of NO and NO 2 to N 2 over the base metal-exchanged Y zeolite catalysts. Ozone for addition to the exhaust stream is suitably generated by passing ambient air through a suitable ozone generator. The ozone containing air is injected into the exhaust stream. Plasma reformed diesel fuel is suitably prepared using fuel withdrawn from the engine's fuel tank. The withdrawn volume of the low volatility diesel fuel is heated and fractionated by bubbling air through it to vaporize a low-boiling fraction of the diesel fuel hydrocarbons. The air-entrained, vaporized diesel fuel fraction is passed through a non-thermal plasma generator to reform the fuel for injection into the exhaust stream. The higher boiling fraction of the fuel is suitably returned either to the fuel tank or to the fuel delivery line for use in the engine. The vaporized fraction of the diesel fuel contains its smaller hydrocarbon molecules. These hydrocarbon molecules are reformed (broken up into smaller radicals and oxidized by ozone) in the hyperplasma reactor. The reformed diesel fuel comprises effective reductant species for NO 2 and is introduced into the exhaust downstream of the ozone addition. As stated above, the ozone oxidizes NO in the exhaust gas to NO 2 . The NO 2 is then reduced to N 2 by reaction with reformed diesel fuel constituents over the dual bed base metal-exchanged Y zeolite catalysts. An efficient non-thermal hyperplasma reactor is used to reform the fractionated fuel stream. The same type of plasma reactor may also be used for ozone generation. In a preferred embodiment, the plasma generator is a tube having a dielectric cylindrical wall defining a reactor space. A linear, high voltage electrode is disposed along the axis of the tube within this reactor space. An outer ground electrode, comprised of electrically conductive wire, is spirally wound around the cylindrical dielectric wall in a sequential pattern having a selected pitch that provides an axially discrete spacing between each turn of the wire. Application of a high frequency, AC voltage to the central electrode creates plasma in the ambient air passed through the reactor. The combination of the helical ground electrode having a discrete spacing between each turn and the linear axial electrode produces intertwined helical regions of active and passive electric fields. The method of the present invention is capable of achieving an average of 95% conversion of NO x to N 2 , at a catalyst temperature of 200° C., over prolonged operation of the dual bed base metal exchanged zeolite catalysts. The reductant species from the reformed diesel fuel do not degrade the catalyst. The exhaust leaving a diesel engine contains unburned hydrocarbons, especially diesel particulates, and carbon monoxide that are preferably eliminated by catalytic oxidation and filtering of the exhaust prior to the ozone addition to the exhaust. Other objects and advantages of the invention will be apparent from a description of a preferred embodiment which follows. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic flow diagram for exhaust from a diesel engine illustrating a preferred method for NO x reduction in accordance with this invention; FIG. 2 is a schematic view of an apparatus and method for fractionation of diesel fuel in the practice of this invention; FIG. 3 is a side view, partly in cross section, of a non-thermal plasma reactor used for treating fractionated diesel fuel to produce a reductant for use in the practice of this invention; FIG. 4 is a schematic view of a dual-bed base metal-exchanged Y zeolite catalytic reduction reactor as used in an embodiment of this invention; FIG. 5 is a bar graph showing the concentrations in parts per million (ppm) of NO, NO 2 , NO x , acetaldehyde (AA), formaldehyde (FA), ethanol, propane, propylene, and carbon monoxide at locations A, B and C in the exhaust stream as designated in FIG. 1 ; FIG. 6 is a graph showing the NO x conversion at the exit of the catalytic reactor versus time-on-stream of the dual bed catalyst over the first two hours of operation; and FIG. 7 is a graph of the concentrations in ppm of NO, NO 2 , N 2 O and NO x at the exit of the catalytic reactor versus time-on-stream of a dual bed catalyst over the first two hours of operation. DESCRIPTION OF THE PREFERRED EMBODIMENT A practice of the invention is illustrated schematically in FIG. 1 . Line 10 represents the flow of the exhaust gas from a diesel engine, not shown. Diesel engines are typically operated at air-to-fuel mass ratios that are considerably higher than the stoichiometric ratio of air to fuel and the exhaust gas contains an appreciable amount of unreacted O 2 as well as N 2 (from the air). The temperature of the exhaust from a warmed-up engine is typically in the range of about 200° C. to about 400° C. The practice of the invention will be illustrated in the case of a diesel engine but it is to be understood that the subject method could be used to treat the exhaust of other lean burn hydrocarbon fueled power sources if diesel fuel is available for the exhaust treatment. In diesel engine exhaust, in addition to O 2 and N 2 , the hot gas also contains CO, CO 2 , H 2 O and hydrocarbons (some in particulate form) that are not completely burned. But the constituent of the exhaust gas to which the subject invention is applicable is the mixture of nitrogen oxides (largely NO and NO 2 with a trace of N 2 O, collectively referred to as NO x ) that are formed by reaction of N 2 with O 2 in the combustion cylinders of the engine (or power plant). The content of NO x in diesel exhaust is typically about 200–300 parts per million (ppm). So the purpose of this invention is to treat nitrogen oxides that constitute a very small fraction of the volume of the exhaust stream. Exhaust stream 10 ultimately flows to a dual bed catalytic reduction reactor 12 for conversion of the NO x content of the exhaust to N 2 . Although not shown in the FIG. 1 exhaust flow diagram for illustration of an embodiment of this invention, the diesel engine exhaust may first be treated by catalytic oxidation and filtration for removal of diesel particulates and other unburned hydrocarbons. Following such oxidation and/or filtration, two important additions are made to exhaust stream 10 before it reaches reduction reactor 12 . Reference is made to FIGS. 1 and 2 . Diesel fuel, suitably from the fuel supply for the engine, is pumped, line 14 to a fuel fractionator 16 . The fuel enters inlet 18 ( FIG. 2 ) and is received in the aeration chamber 20 as fuel volume 28 . Aeration chamber 20 and fuel volume 28 are heated using external heating coil 22 to a suitable temperature, e.g. 200° C., for air vaporization of the low volatility hydrocarbon fuel. Ambient air is inducted, by blower means not shown, through air line 24 to vertical air feed tube 26 and, thus, into the bottom of chamber 20 below the surface of fuel volume 28 . The stream of air exits feed tube 26 through quartz frit 30 and bubbles up through fuel volume 28 . Thermocouple 32 , inserted through an otherwise closed end 34 of air feed tube 26 , extends down feed tube 26 to a suitable location below the surface of fuel volume 28 . Thermocouple 32 is used in a known manner for control of heater coil 22 in maintaining the temperature of fuel volume 28 at temperature suitable for fractionation of the diesel fuel. The air stream bubbling through the heated fuel volume 28 of diesel fuel leaves the fractionator 16 through air/fuel outlet 36 . The ambient air bubbling through the heated fuel volume 28 strips out (vaporizes) a fraction of the fuel volume 28 to form an air stream carrying the more volatile, lower molecular weight hydrocarbons from the fuel. This hydrocarbon laden air stream flows through line 38 to a non-thermal, highly efficient plasma reactor, HP- 1 , for plasma reforming of the hydrocarbons. The structure and function of the efficient plasma reactor HP- 1 , termed a hyperplasma reactor, (and similar reactor HP- 2 for ozone generation from ambient air) will be described below in connection with the illustration of FIG. 3 . In plasma reactor HP- 1 , the hydrocarbon molecules fractionated from the diesel fuel volume 28 are reformed and oxidized to form reactive NO x reduction material, still carried in the air stream, through line 40 into exhaust stream 10 . The reformed fuel comprises hydrocarbons such as propane and propylene and oxygenated hydrocarbons such as formaldehyde, acetaldehyde and ethyl alcohol. When fractionator 16 is used in combination with an operating engine the fractionation process is a continuous process. As the air stream, line 24 , strips out a relatively more volatile portion of fuel volume 28 the remainder of volume 28 becomes smaller and enriched with less volatile hydrocarbons. This portion of the withdrawn fuel is returned either to the fuel tank or to the fuel delivery line for combustion in the engine. Accordingly, it is preferred that diesel fuel be pumped continually to and from the fractionator 16 as follows. A measured volume of fuel is introduced into inlet 18 continuously or in suitable periodic batches. As fractionated fuel is removed in the flowing air stream, line 38 , residual fuel is drawn from fuel volume 28 through the bottom of fractionator 16 at outlet 42 and returned either to the fuel tank or to the fuel delivery line. The return flow of fuel is controlled by valve 48 , or other suitable means, to maintain a suitable fuel volume 28 in chamber 20 . Thus, in an operating engine embodiment, fuel and air are continuously delivered to fractionator 16 through fractionator inlets 18 and 24 , respectively, and streams of air/fractionated fuel and residual fuel are withdrawn through fractionator outlets 36 and 42 . In FIG. 3 , a non-thermal hyperplasma reactor 100 is illustrated that is suitable for use in reforming fractionated diesel fuel in a stream of air, and for generating ozone in a stream of air, both for use in the practice of this invention. The reactor 100 is sized and powered for its specific application. Non-thermal plasma reactor 100 comprises a cylindrical tubular dielectric body 102 . The reactor 100 has two electrodes, a high voltage electrode 104 and a ground electrode 106 , separated by the tubular dielectric body 102 and an air gap 108 . The high voltage electrode 104 is a straight rod placed along the longitudinal axis of the tube 102 . The ground electrode 106 is a wire wound around the tubular dielectric body 102 in a helical pattern. The helical ground electrode 106 in combination with the axial high voltage electrode 104 provides intertwined helical regions of active 110 and passive 112 electric fields along the length of the reactor 100 . The helical active electric field 110 around the ground electrode 106 is highly focused for effective plasma generation for the reforming of diesel fuel and for ozone generation. A high voltage, high frequency electrical potential is applied to the end leads 114 , 116 to the center electrode. The helical outer ground electrode 106 is grounded as indicated at 118 . In the operation of the plasma reactor 100 as HP- 1 for reformation of the fractionated diesel fuel, a mixture of the fuel and air flows through the INLET of reactor 100 around center electrode 104 and within dielectric tube 102 and out EXIT end in the direction of the arrows seen in FIG. 3 . The electrical potential applied to center electrode 104 generates the above described active 110 and passive 112 fields within the reactor 100 . These high potential, high frequency fields 110 , 112 generate reactive hydrocarbon species and oxygen species within the flowing air/fuel stream in the air gap 108 which results in the production of oxygenated hydrocarbon radicals or other activated species. This oxygenated hydrocarbon-containing air stream leaves the reactor 100 (HP- 1 ), enters line 40 , and is immediately introduced into the exhaust stream 10 as indicated in FIG. 1 . As will be described in detail below, electrical power is applied to HP- 1 reactor at a level that is suitable to generate the reformed oxygenated hydrocarbon material. HP- 1 reactor is located close to, but away from, the hot exhaust pipe. HP- 1 plasma reactor is a non-thermal reactor but entering stream 38 may be above ambient temperature because ambient air was used to vaporize heated fuel volume 28 in fractionator 16 . In addition to air/reformed diesel fuel stream 40 , ozone is generated in an ambient air stream and injected into exhaust stream 10 . Referring again to FIG. 1 , ambient air is blown through a second plasma reactor, HP- 2 . Preferably, plasma reactor HP- 2 is a suitable adaptation of a non-thermal plasma reactor 100 as described with respect to FIG. 3 . Alternatively, a commercial ozone generator may be used. When the ambient air is subjected to the high intensity alternating electric field in HP- 2 a fraction of the air is converted to ozone and the ozone/air mixture leaving HP- 2 through line 44 is injected into exhaust stream 10 downstream of line 40 , the reformed diesel fuel containing stream. As seen in FIG. 1 , the hot exhaust stream 10 containing suitable additions of reformed diesel fuel, stream 40 and ozone, stream 44 , enters the dual bed catalytic reduction reactor 12 . As illustrated in FIG. 4 , catalytic reduction reactor 12 houses a dual bed reduction catalyst. The upstream catalyst bed comprises a volume of sodium (or barium) Y zeolite, indicated as NaY (or BaY), and the downstream bed, usually a smaller volume, comprises copper Y zeolite (indicated as CuY). Y-type zeolites are aluminosilicate materials of rather specific alumina-to-silica ratio and crystal structure. They have ion-exchange capability and they are commercially available, often in their Na + ion form. In the practice of this invention NaY may be converted to BaY or CuY by aqueous ion exchange. The temperature at the reactor 12 outlet is used in controlling plasma power density in HP- 1 and HP- 2 , respectively and the volumetric feed ratios of reformed diesel fuel, line 40 , and ozone, line 44 for effective operation of the catalytic reduction reactor 12 . For example, the temperature at the outlet of the reduction catalyst may be monitored for effective exhaust gas treatment by thermocouple (indicated at T 1 ) or other suitable temperature sensor(s). Temperature data is transmitted to a digital controller (not shown) for controlling plasma power density and amount of stream additions through lines 40 and 44 . Stream 46 indicates the treated exhaust being discharged from the exhaust system. The heat and hydrocarbon content of stream 46 may be utilized by using it to supplement or replace a portion of air stream 24 entering fuel fractionator 16 and/or the air stream entering ozone reactor HP- 2 . These recycled exhaust streams 50 (to fractionator 16 ) and 52 (to HP- 2 ) are shown schematically in FIG. 1 . In general, the requirement for reformed diesel fuel constituents increases with increased NO x content in the exhaust and increased exhaust temperature (catalytic reactor temperature). For example, about 8 moles of reformed fuel, normalized as C 1 hydrocarbon per mole of normalized NO x at a catalyst temperature of 200° C. Conversely, the ozone requirement is greatest at catalytic reactor temperatures of 150–200° C. and decreases to zero at reactor temperatures of 350–400° C. The following experiments illustrate the practice and effectiveness of the invention. Experimental A simulated diesel exhaust gas composed, by volume, of 181.5 ppm NO, 24.5 ppm NO 2 , 17.6% O 2 , 2% H 2 O and the balance N 2 was used in the following laboratory scale tests. This simulated exhaust gas was used as stream 10 in FIG. 1 for eventual catalytic reduction in a dual bed catalytic reactor as indicated at 12 in FIG. 1 . The dual bed catalytic reactor was made of a quartz tube with a ¼ inch (about 6.4 mm) outside diameter, 4 mm inside diameter, and containing NaY zeolite in an upstream bed and CuY in the downstream bed. CuY zeolite was made from NaY by aqueous ion-exchange of NaY obtained from Zeolyst Corp. The amounts of NaY and CuY used were 422 mg and 211 mg, respectively. The catalytic reactor was placed in an electric furnace whose temperature was controlled by a thermocouple located at the exit of the catalytic reactor. In these tests the catalytic reactor was maintained at 200° C. A batch operation fractionator like that illustrated in FIG. 2 , but without fuel exit line 42 , was made of a quartz bulb. Raw diesel fuel was contained in the bulb at a sufficient level. Air fed through the inlet tube and the vertical air feed tube flowed through the quartz frit making bubbles. The air bubbles generated a large surface area for diesel fuel evaporation while agitating the liquid fuel during their travel upward, resulting in an enhanced evaporation of diesel fuel. The temperature of the liquid fuel was controlled by adjusting the electric power supply to the heating element in response to the readings of a thermocouple. Though the preferred temperature range is 100–250° C. to fractionate a low-boiling portion of the fuel, a temperture of 200° C. was employed. The flow rate of ambient air to the fractionator was 34 cubic centimetes per minute at standard conditions (sccm). The air and low-boiling diesel fraction flowed through the exit to the hyperplasma reactor (HP- 1 ) for reforming. A hyperplasma reactor for the fractionated diesel fuel was made in accordance with the reactor illustrated in FIG. 3 . The reactor was made of a 8 mm o.d. (6 mm i.d.) quartz tube which served as a dielectric barrier. With the high voltage electrode in the center, it was made in a concentric cylindrical geometry. Air and vaporized diesl fuel at an unmeasured exhaust temperature from the fractionator entered HP- 1 . HP- 1 was unheated and the air/fractionated fuel mixture flowed through the annular space between the center elctrode and the quartz tube. The ground electrode was made of a Ni wire wound around the outer surface of the quartz tube in 20 turns at a pitch of 2 mm. The total length of the plasma generating area was 4 cm. An alternating high voltage of +/−7 kV was applied to the center electrode at a power level of 2.7 J/L. The reformed fuel was analyzed and contained propane, propylene, formaldehyde, acetaldehyde and ethanol. The carbon content of the reformed fuel may be normalized in terms of molar methane (C 1 ) content for purposes of simplifying process control. The amount of C 1 content of the reformed fuel is based on the NO x content of the exhaust and the temerature of the exhaust or catalytic reactor. The reformed diesel fuel was fed to the simulated diesel engine exhaust gas stream before the stream reached the dual bed catalytic reactor. A commercial ozone generator was used as HP- 2 . Air at room temperature was fed to the generator at 45 sccm and the air/ozone output of the generator containing 1200 ppm ozone was added to the simulated diesel exhaust downstream of the addition of reformed fuel and before the exhaust stream was passed through the catalytic reactor. This concentration of ozone in the air stream was suitable for the catalytic reactor operating at 200° C. and lower. The ozone requirement decreases, generally proportionately, as the temperature of the reactor increases. When the catalyst is at about 350° C. and higher, no ozone addition is required. The simulated exhaust, reformed fuel, and ozone entered the dual bed catalyst reactor at a combined flow rate of 179 sccm and at a pressure of 101.3 kPa. The C 1 /NO x ratio at the inlet of the catalyltic reactor (sample location B in FIG. 1 ) was around 8. The space velocity in the 200° C. reactor was 11 k/h for the NaY bed and 22 k/h for the CuY bed. At higher catalyst temperatures the proportion of reformulated fuel, C1, increases. FIG. 5 shows the product distribution measured by an FTIR at each sampling position (A, B and C in FIG. 1 ) in the system. As specified above, the normalized exhaust composition with the hyperplasmas turned off was 181.5 ppm NO and 24.5 ppm NO 2 . Sampling position A shows the effect on exhaust gas composition of the addition of reformed diesel fuel. Sampling positon B shows the effect on exhaust gas compositon following the ozone addition. And sampling positon C shows the compositon of the gas leaving the catalytic reduction reactor. FIG. 5 indicates that the major role of the first hyperplasma (HP- 1 ) is to produce acetaldehyde (AA), while the major role of the second hyperplasma (O 3 generator) is to oxidize NO to NO 2 in the exhaust gas stream. The data on NO x concentrations in FIG. 5 clearly demonstrates that the subject process can achieve 95% NO x conversion at the catalyst temperature of 200° C. This is a remarkable performance better than anything reported in the literature using diesel fuel as the reductant. FIG. 6 shows the transient NO x conversion performance of the dual-bed catalytic reactor at 200° C. for the first two hours of operation. When the exhaust flow stream was fed to the catalytic reactor, the NO x conversion reached above 90% and then decreased slightly, followed by a steady increase to steady-state conversion of 95%. There was no noticebale deactivation of catalyst activity. FIG. 7 shows the transient evolution of N-containing species at the outlet of the catalytic reactor in the D/SCR system. The catalysts reached the steady state in about 90 minutes on stream without any indication of catalyst deactivation. The amounts of other N-containing species such as N 2 O, NO 2 , HCN and NH 3 were negligible. The invention has been described by illustration of specific embodiments but the scope of the invention is not limited to them.

4y

FIELD OF THE INVENTION This invention relates to repair techniques for matrix addressed displays. More particularly, it relates to a matrix addressed display having apparatus for repairing and operating in the presence of line defects and to a method for effecting such repair. Of particular interest are active matrix liquid crystal displays, though the techniques taught herein apply to all matrix addressed displays having data drivers at both the top and bottom of the display. BACKGROUND ART A portion of a thin film transistor liquid crystal displays (TFTLCDs), also known as active-matrix liquid crystal displays (AMLCDs), are discarded from the manufacturing process because of data line defects. By repairing these defects the yield increases and the manufacturing cost decreases. Defective data lines in TFTLCDs result from a number of mechanisms. Some occure due to metallurgical problems such as contamination during lithographic patterning of the data lines which manifest in opens or shorts. The shorts may occur between data lines themselves or between a data line and a gate line, or between a data line and some other part of the display circuit, such as the top plate. Other failures occur because some of the drivers on a data driver module fall below specification or fail, or because of a failure in the connection between the data lines on the glass and the driver chip. Shorts can be removed by laser ablation, but some kinds of shorts (such as crossover shorts and top plate shorts) require that an open also be created by the laser ablation step. At present, the opens can then repaired as illustrated in FIG. 1 . In FIG. 1, the array portion 20 of an active matrix liquid crystal display is illustrated. A series of data lines 22 are each driven by one output of a data driver 24 . For high resolution arrays which have a large number of lines per unit length, it is typical to have successive data lines 22 driven from the top and bottom of the array 20 . Gate lines 26 are driven by gate line drivers (not shown). As is well known in the art, there is a thin film transistor located adjacent to each of the crossover points of every data line 22 and gate line 26 which drives a pixel or subpixel of the array 20 . FIG. 1 includes a data line 22 A which is driven from the top of array 20 . Line 22 A is open, that is, lacks electrical continuity due to a gap 28 so that transistors at intersections of data line 22 A and gate lines 26 below gap 28 are not activated. This produces a so-called “line defect” which is highly visible and makes the panel totally unacceptable for sale as a commercial product unless an appropriate repair is effected. Conventionally a repair is made by mechanically connecting an insulated wire 30 between the top and bottom portion of the open data line. This method of repair is usually called a “yellow wire” repair, since this color of wire is often used to repair similar problems in printed circuit boards. The “yellow wire” jumper in FIG. 1 can physically run off the array substrate or be lithographically incorporated as a spare line on the array substrate. While correcting for opens, this type of repair introduces new problems. If the jumper wire is located on the glass, peripheral space on the substrate must be allocated, which increases the bezel area of the display package. Most importantly, jumper wires on the substrate must cross over or under other signal lines, and signal degradation will occur due to capacitive crosstalk with these other signal lines. If the jumper wire runs off the glass, signal degradation may occur due to other electromagnetic pickup. All of these problems also make it difficult to extend this repair method to repair more than one or two defective lines. Also, not all defects can be repaired in this manner. For example, defective data lines which are due to problems with the driver chip or driver chip connection usually require replacing the data drivers or discarding the entire defective panel. SUMMARY OF THE INVENTION It is a principal object of this invention to provide a matrix addressed display in which data line defects can be easily and inexpensively repaired. It is another object of this invention to provide a method for easily and inexpensively repairing data line defects. It is still another object of this invention to provide circuitry for manipulating pixel data so that an image is properly displayed when a data line repair is made. It is yet another object of this invention to provide a method for manipulating pixel data so that an image is properly displayed when data line repair is made. It is an additional object of the invention to provide a bus and repair pad design which is flexible, has a minimal crossover capacitance, and which is amenable to short-distance wire bonding. In accordance with the invention several extra driver outputs are included in each data driver integrated circuit for repair as shown and described with respect to FIG. 2 . These auxiliary drivers are connected to the defective lines via a metallurgical bonding technique. Open data lines are fixed by connecting auxiliary drivers, on the opposite side of the display, to the undriven ends of the open data lines. Weak/failed data drivers or low impedance loads can be corrected by adding a auxiliary driver in parallel with the existing driver, or opening the failed line and using one or more auxiliary drivers. In the following discussion a pixel refers to a single picture element. In the case of a color display such as a TFT/LC display, the pixel is comprised of a trio of red, green and blue subpixels. In some cases four subpixels make up a picture element. In the case of a monochrome display, the smallest element in the display is the pixel, that is, there are no subpixels. It is also assumed in the discussion below that the data drivers in a color display accept three data elements at once, one each for red, green and blue. Though this is typical in the industry, other numbers of inputs can just as easily be accommodated in the techniques discussed. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic plan view of a liquid crystal display panel illustrating a conventional repair technique. FIG. 2 is a block diagram of a liquid crystal display using the active line repair techniques in accordance with the invention. FIG. 3 is an example of a defect map for storing information concerning defective lines. FIG. 4 is a general block diagram of a simplified liquid crystal display in accordance with the invention. FIG. 5 is an illustration of the timing of normal and defect data supplied to the simple liquid crystal display represented in FIG. 4 . FIG. 6 is a first embodiment of a data control block which may be used to control data in a matrix addressed display in accordance with FIG. 4 . This approach is referred to as the serial-processing approach. FIG. 7 is a second embodiment of a data control block which may be used to control data in a matrix addressed display in accordance with FIG. 4 . This approach is referred to as the source-synchronous-parallel-processing approach. FIG. 8 is a third embodiment of a data control block which may be used to control data in a matrix addressed display in accordance with FIG. 4 . This approach is referred to as the display-synchronous-parallel-processing approach. FIG. 9 is a block diagram of a new subpixel memory stacker useful in the embodiments illustrated in FIG. 7, FIG. 8 and FIG. 9 . FIG. 10 is a diagram showing three possible ways to distribute the repair lines among the data driver outputs in a matrix addressed display. FIG. 11 is a detailed plan view of a bus structuring providing simple repair paths for defective lines. FIG. 12 are exploded views of the bus structure of FIG. 11 . FIG. 13 is an enlarged plan view of the layout of various metal conductors used in the bus structure of FIG. 11 . DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to FIG. 2, in an array 32 in accordance with the invention, the preferred manner of adding the auxiliary drivers to the glass panel 34 is to increase the number of output lines of each data driver 36 . This results in the smallest increase in additional space and allows use of the highly integrated electronics in each driver. For example, use can be made of drivers having 201 outputs instead of 192 . Several existing data drivers may be programmed for 192 or 201 outputs by simple selection. The extra nine lines (or less) can be used as auxiliary driver outputs. When the data lines of the display are connected to each data driver, the auxiliary data drivers are allocated to the end of the driver which is clocked in last as shown in FIG. 2 . An allocation of S spare lines 38 per driver 36 will result in S*D total spare lines where D is the number of drivers. Metal traces 40 must be patterned onto the glass of the display which enable a connection to bad data lines. These spare line traces 40 are placed perpendicular to display data lines as shown in FIG. 2 . If laser welding is used to make a connection then the spare traces 40 should cross over data lines from the top and bottom data drivers. However, if wire bonding is utilized these traces only need to cross the data lines from the driver on one side. The opposite data lines terminate in line extension pads which are wire bonded to repair pads on spare traces. When a connection is made between a spare driver line and the defective line as previously described only one laser or wire bond is needed. This decreases the amount of time necessary to mechanically connect. Either process can be automated to minimize repair time. The display controller 42 , which receives display data, denoted as RGB Data on data bus 44 , and appropriate control signals on control bus 46 must be provided with the necessary coordinate column number of the offending lines. To this end, a defect map PROM 48 is added to each TFT/LCD glass panel 34 . PROM 48 may be a slow, small, serial device having a cost of one to two dollars, that loads the display controller's defect map on reset. The data stored in PROM 48 is determined by testing the panel. Preferably, before it is fully assembled, the panel is tested in accordance with the method, and using the apparatus, disclosed in U.S. Pat. No. 5,179,345 to Jenkins and Wisnieff, but it will be understood that other methods and apparatus may also be used to generate the data. The electrical connector used to connect the LCD panel to a data source such as a host computer needs only one extra line (not shown in FIG. 2) for the PROM chip select. Other PROM signals can be multiplexed on existing lines. After reset, controller 42 uses the addresses in the defect map to determine when to latch the incoming data into temporary memory for use on the spare lines 38 . At the appropriate time the display's data drivers are loaded with the regular data plus the information for the defective lines as more fully explained below. FIG. 3 shows how an example defect map PROM can be made. Each entry in the PROM has three fields which describe the pixel correction addresses: the horizontal count, the subpixels correction address and correction destination in which to store the data. The first field tells the controller which incoming pixel data to store. The second defect data field describes which subpixels of the pixel to keep and the last field tells where to store that data. The pixel address to be corrected only needs to contain enough bits to describe the data line location. Ten,bits of address, for example, would be needed to describe 640 pixels per line. The subpixel correction address needs three bits for red, green or blue; if one of the subpixels needs correction then the appropriate bit is cleared to zero. For the example with 6 spare lines per driver and 10 drivers then the table must contain 60 entries. This PROM would need 60 entries with 16 bits per entry. This results in a requirement for 960 bits to be stored, which easily fits into an eight pin serial PROM. FIG. 4 illustrates in greater detail a possible structure for controller 42 of FIG. 2 and its connection to data drivers 36 . The serial pixel data stream provided by bus 44 is received by a data format circuit 50 which divides the data into odd column data on bus 52 and even column data on bus 54 . Data format circuit 50 also provides data address information for each set of data to a first compare circuit 56 and a second compare circuit 58 . Circuits 56 and 58 compare the data address provided by data format circuit 50 to the addresses in defect PROM 48 . When a match in the addresses occurs, a respective one of latch and store circuits 60 and 62 stores the current data for presentation to the data drivers 36 by way of a respective switch 64 or 66 operated by a control circuit 68 . All of the operations described above with respect to FIG. 4 are controlled by a timing circuit 70 which receives control signals for horizontal and vertical synchronization as well as a pel clock by way of bus 46 . FIG. 5 illustrates the horizontal line time makeup utilized in the circuit of FIG. 4 for the simple case of one data driver chip on the top and one on the bottom. In a practical display there will be several drivers on the top and the same number on the bottom. This simplification is used for clarity of presentation. In a firsts time interval T, normal data for picture elements not associated with defective lines is written into the data drivers. In a subsequent time interval T′, data required to write to picture elements associated with defective data lines is written into the data drivers. Finally, there is a retrace time between lines. FIG. 6 illustrates an implementation of the circuits which appropriately modify the data stream of the drivers. This implementation is a serial pixel processing approach and is especially useful when the pixel count is small, say VGA. The circuit count is small, but the pixel processing rate is the pixel clock rate from the source. The contents of the serial defect PROM on the TFT/LCD is converted into a parallel bit stream by a serial to parallel circuit 72 and copied into a fast defect map RAM 74 . This loading occurs only upon reset. The RAM must allow addressing at the pixel clock rate. The data structure of the controller defect RAM 74 is the same as that of the serial defect PROM 48 . Field one of the PROM or RAM defect data is used as one input to an address comparator 76 . The other input to the comparator is the current pixel count from pixel counter 78 . Fields two and three of the defect data generate an address for the dual subpixel memory stacker 80 . At the beginning of each horizontal line all counters are reset. Therefore, the defect map counter 82 points to its first entry. As valid data occurs, pixel counter 78 is incremented. If the pixel count equals the pixel column number stored in the defect RAM a signal is given to latch that pixel data and to increment the defect map counter 82 to point to a new address. The subpixel field provides the necessary information to the dual memory stacker 80 to determine which subpixels are to be corrected and where they should be stored in the stacker. After each set of top and bottom drivers is loaded, the subpixel memory stacker 80 is put in read mode and loads the data into the auxiliary data drivers via the multiplexer 88 and the data steering circuitry 89 . At the same time the repair data is being loaded into the drivers, a FIFO (First In First Out Circuit) 86 , clocked by a control circuit 87 , buffers the non interrupted data stream. This is required because the incoming data stream cannot be stopped while the repair data is being loaded into the data driver chip. The size of the FIFO 86 only needs to be a little larger in depth than the total number of pixels capable of being repaired. After the repair data drivers have been loaded, the memory stacker 80 is reset, put back into write mode and normal data is sent from the FIFO 86 to the display by way of selector 88 . This process continuously repeats until all data drivers are loaded. Subsequently, the circuits are reset and operations begin again. FIG. 7 shows an alternative implementation which is called source-synchronous-parallel-pixel processing. Blocks with like numbers function as described above for FIG. 6 . Defect data is stored as described above. The incoming pixel data stream is initially broken into two data streams by the data steering circuitry 89 . One stream is for drivers on the top of the display and the other for drivers on the bottom of the display. Data in the top and bottom branches run at half the Source pixel rate and this is an advantage for large pixel count displays which have high clock rates. Additional circuitry is needed to process data in parallel. The basic function of comparing the incoming pixel address to the address of a defective line and latching that data if a match is found is similar to that described above. In this case, however, each of the two data paths have FIFOs and latches. Also shown duplicated are the compare and defect RAM circuits. This is shown for continuity of concept from FIG. 6. A single compare and defect RAM, however, can be used as long as the address generation and the defect RAM are changed accordingly. In this case, we would compare not a pixel column address, but a pixel-pair column address and the RAM would have to control two subpixel memory stackers. Note also that the repair data from the top data path is now multiplexed into the bottom data path and vice versa. This approach is called source synchronous because the writing into the latches and FIFOs are synchronous with the data source at half the pixel clock rate. The output to the display can be asynchronous and at a frequency set by oscillator 90 . In fact, the repair data can even be sent out at a different clock rate than the normal data if the system design requires it. The circuit of FIG. 8 is yet another embodiment of the control block 42 of FIG. 2 . This case is called display-synchronous-parallel-pixel processing. The key difference in this implementation is the placement of the pixel processing circuitry after the FIFO circuit 86 in the data stream. This enables the pixel processing circuits to operate independently of the source pixel rate. More specifically, the implementation shown in FIG. 8 places the Dual subpixel Memory Stacker (DSMS) between the FIFO and the display. The previous implementation placed it across the FIFO. In the prior implementation the DSMS accepted data from the pixel data source and would later supply that data as ALR repair data to the output data stream. The FIFO buffers the incoming data from the pixel source while the ALR data is being placed into the output data stream. Because the data rate from the pixel source can be quite different than the data rate to the display, the DSMS in the prior scheme might need to accept and supply data at two possibly quite different rates. This can complicate a design. In addition, systems that are designed to provide multiple parallel data paths in to the display can create a problem for buffering the repair data in the prior scheme. In the implementation shown in FIG. 8, the FIFO is used in exactly the same way as in the prior scheme. However, the DSMS now accepts data from the output of the FIFO and not from the original pixel data source. Therefore, the data rate into and out of the DSMS is identical. This simplifies the design of the DSMS. In addition, the higher resolution displays that will be on the market soon are likely to use parallel data paths into the display. Therefore, the data rate into the display is likely to be substantially lower than the data rate from the source. This can greatly simplify the design while lowering the cost and power requirements. Additionally, because the embodiment of FIG. 8 does not store any data in the DSMS until it is actually being sent to the display, the data buffering scheme is much simpler. The dual subpixel memory stacker described in the previous implementations contains circuitry which appropriately sorts and stores subpixel data for tile auxiliary drivers. FIG. 9 shows the circuitry comprising a dual pixel memory stacker for the case of 6 repairs per driver chip. During the write mode the repair data subpixel fields are used to determine if one or more subpixels must be stored into the A, B or/and C RAMs 100 , 102 and 104 , respectively. These RAMs may be DRAMS, SRAMS or simple transparent D latches with addressing circuits. The stackers track which address is available to store new information. To illustrate, let the first cell of RAM A be filled with prior data. That cell contains data for the first spare of that driver. Now a new subpixel field address comes into the unit because the defect map counter 82 points to the next entry. This subpixel field is, for example 100100, which means the green and blue subpixel data must be saved and the data are to be placed in the next two available storage locations. This causes the triple 1-of-3 multiplexers 106 , 108 and 110 , respectively, to route the green channel to cell one of RAM B and the blue channel to cell one of RAM C. Next this data is written into the RAM banks. The LUT or decode unit 112 generates the next set of addresses based upon the next subpixel fields and the address of the prior open cell. In this example it would point to cell 2 of RAM A as the next available storage location. After each set of top and bottom drivers are loaded, the LUT or decode unit 112 is reset and the process begins for the next set of drivers. The LUT or decode unit 112 may be eliminated by precomputing the multiplexer and RAM addresses for each panel. Instead of a subpixel correction and destination address, the serial PROM and defect map RAM would contain the multiplexer and RAM addresses. Additional bits would be used to signal a write operation to the top or bottom data drivers. Various modifications to the invention will be suggested. FIG. 10 shows three ways in which the repair lines can be distributed amongst the data drivers. FIG. 10A shows the case previously described in which the last several outputs of each data driver are reserved or are uncommitted for use as repair drivers. Note that the wiring from these repair outputs crosses over all the outputs of this one driver. Line lengths and capacitance are small. FIG. 10B has the repair lines distributed, perhaps evenly, amongst the driver outputs. Line lengths are even shorter and fewer crossovers and capacitance result. The timing and control is different than case A, but it may be the preferred way given other system constraints. FIG. 10C has all of the repair lines attached to the last driver outputs of the last driver in the string. Repair line lengths, crossovers and capacitance are larger than case A, but in some respects the timing and control may be simpler depending, again, on system constraints. In all these cases, there is a similar set of drivers at the other end of the data lines. Referring to FIG. 11, a portion of the bus structure at the top edge of the panel is illustrated, with the TFT array not being shown in the figure. The array is located off and below the portion shown. At the top of the figure, electrostatic discharge protection devices 120 are shown. Above these devices is a shorting ring 133 of a type generally known in the art, and above this, pads 135 for tape automated bonding (TAB) connections to the top data driver chips. As discussed previously, alternate lines 124 are driven from the top or bottom. Lines driven from the bottom are connected to line extension pads 126 which are disposed adjacent to repair pads 128 . The repair pads are connected to a horizontal line 130 of a bus shown generally as 132 . The bus lines are connected to six uncommitted driver outputs from data drivers 36 (FIG. 2) and as shown in FIG. 10C, by way of vertical lines 134 . Referring to FIG. 12, an example of the entire repair bus network is shown for a driver group pair. Both top and bottom repair bus networks are shown, with the TFT array 137 in the center. The six uncommitted output lines of bus 132 are grouped as three groups 140 , 142 , and 144 of two lines each. In each group, one uncommitted output line is connected to repair pads on one half of the driver group. One line extends the entire length of the driver group, and the other extends over half the length of the driver group. With this bus configuration, only one defective line of a given color can be repaired within each half of a data driver group. If two or more lines with the same color are defective within half of a driver group, only one can be repaired. It should also be noted that with this bus configuration, the maximum number of crossovers of a repaired line with other data lines is the number of driver outputs of a single driver. By limiting the number of crossovers in this way, the integrity of the active line repair data signals is maintained, because the parasitic capacitance of the line is held to an acceptable level. Referring to FIG. 13, the detail of a line extension pad and repair pad pair are shown. The repair bus lines 130 must cross under other data lines 124 and (as shown in FIG. 11) and are fabricated with gate metal. In this embodiment, the gate metal bus lines 130 also have a redundant spine 160 of ITO which is also used to connect to the repair pad region through ITO layer 166 . Vias 162 and 164 are made in the passivation layer insulator, to provide an opening to both the repair pad 128 and line extension pad 126 . A layer of ITO 166 is present on both pads. In this way, the layer structure of both pads is identical, which consists of ITO 166 , data metal 168 , vias 162 and 164 . This pad symmetry may facilitate reliable bonding between the two pads. To effect a repair of a defective line, the line extension pad and repair pad must be connected together. This may be done using a variety of wire bonding or laser welding techniques. Examples include ball bonding, wedge bonding, and other techniques well known to those skilled in the art. One of the advantages of the present invention is that only one bond is required to implement a repair, and the connection points are the repair and line extension pads, which are adjacent to each other. The preferred method of making connection is disk bonding. This technique uses a combination of ultrasonic energy and compression to bond a disk of metal between the line extension pad and the ALR repair pad, using a bond tip. The disks are made by punching out a small dot, about 100 microns in diameter, from a thin foil of aluminum, about 40 microns in thickness. Other soft metals may also be suitable. The disks are distributed on a flat surface, and picked up individually by the bond tip. The bond tip is a precision machined tapered cone with a a tip area slightly larger than the dot diameter, and also of a size to cover both the repair pad and line extension pad pair. The bond tip has a groove running from one side of the tip to the other. This groove allows efficient transfer of ultrasonic energy from the bond tip to the disk and substrate surface. During the bonding process, the disk metal extrudes outward forming a button shape, with a ridge of metal left from the impression of the groove in the bond tip. This bond is mechanically robust, and forms an electrical connection between pads with a resistance less than 1% that of a typical data line in the array.

4y

BACKGROUND OF THE INVENTION The present invention relates to a superconducting material and more specifically to a superconducting material suited particularly to the electrodes, wirings, etc. of semiconductor devices and the like. Conventional metallic materials exhibiting superconductivity above the liquid helium temperature (4.2° K.) include metals such as niobium and lead, and alloys such as Nb 3 Sn. Where the electrodes and wirings of a semiconductor device are to be formed from such superconducting materials, it is customary to use niobium, lead or the like capable of being rather easily formed into thin film through electron beam deposition, sputtering or the like process. Although niobium, lead and the like can be easily formed into thin films, the low melting points thereof present various problems including failure in a high level of heat treatment that is carried out after film formation in the step of producing a semiconductor device; a difficulty in fine patterning through dry etching; and a liability of the characteristics of a thin superconducting film formed therefrom to change in heat cycles between room temperature and a low temperature. Niobium and lead as the conventional superconducting materials are notably different in characteristics from polysilicon, aluminum, tungsten, etc. used as the materials in customary processes for producing a semiconductor device. This presents a difficulty in producing therefrom a semiconductor device having fine and stable superconducting wirings. Electrodes and wirings having such an extremely high conductivity as to ward off increase in electric resistance even if they have a decreased cross-sectional area have recently been in strong demand in step with a remarkable progress of miniaturization and an increase in the operation speed of semiconductor devices. However, the formation of the electrodes and wirings of semiconductor devices from superconducting materials having the highest conductivity has involved the many problems mentioned above and, hence, has encountered a difficulty in materialization thereof. SUMMARY OF THE INVENTION The present invention provides a superconducting material which can solve the above-mentioned problems of the prior art and is highly adapted to customary processes for producing a semiconductor device, and which exhibits superconductivity above the liquid helium temperature (4.2° K.). The present invention also provides an electrode and wiring made of a superconducting material suited to a semiconductor device having a high density of integration. The present invention further provides a semiconductor device having electrodes and wirings made of a superconducting material which has a high density of integration and a capability of high speed operation. In accordance with the present invention, a material containing silicon and comprising tungsten or molybdenum as the main component is used as a superconducting material in order to provide the above-described characteristics. Tungsten and molybdenum are not only low in electric resistance (10 μΩ.cm in the case of a thin film) and high in melting point (3,300° C.) but also capable of being easily fine-patterned through dry etching using a gas containing SF 6 or Cl 2 . In view of this, they are widely used as barrier metals in the electrodes, wirings and contact portions of semiconductor devices, and can be expected to be usable in many other applications. However, the superconducting transition temperatures, Tc, of tungsten and molybdenum themselves are quite low and it is, for example, 0.012° K. in the case of tungsten. It has been discovered that the incorporation of silicon to tungsten or molybdenum is very effective in providing a Tc of above 4.2° K. (the liquid helium temperature), for example, 4.5° K. In addition, it has been discovered that the excellent properties inherent in tungsten and molybdenum as the materials of electrodes and wirings of semiconductor devices do not largely change even when 2 to 40 atomic % of silicon is incorporated in tungsten or molybdenum. Furthermore, a thin film thereof containing silicon can be easily formed through either customary sputtering or low-pressure chemical vapor deposition (CVD) using tungsten hexafluoride (WF 6 ) or molybdenum hexafluoride (MoF 6 ). BRIEF DESCRIPTION OF THE DRAWINGS FIGS. 1a to lc are process diagrams illustrative of a process for producing the semiconductor device as one embodiment of the present invention. DETAILED DESCRIPTION Tungsten films containing silicon were grown on respective single crystal silicon substrates at a substrate temperature of 236° C. or 354° C. by the low pressure CVD method using WF 6 and SiH 4 as source gases. In addition to WF 6 and SiH 4 , argon was used as the carrier gas. The total pressure was 0.65 Torr in all runs. The resulting films containing impurities were examined by Auger electron spectroscopy (AES) to calculate the amounts of the impurities based on the sensitivity correction coefficient. Table 1 shows the conditions of formation, thicknesses, resistivities at room temperature of the respective tungsten films, the amounts of silicon contained in the respective films, and the amounts of oxygen and fluorine contained as the impurities in the respective films. The electric resistances of the tungsten films were measured using respective samples prepared by a procedure of patterning a tungsten film formed on a single crystal silicon substrate into the form of a four-terminal element using the customary photolithographic technique. The patterning of the tungsten film was effected by removing the unnecessary portions thereof through well-known reactive ion etching using SF 6 . These samples were cooled to the liquid helium temperature (4.2° K.), and the electric resistances of the samples were measured by the well-known four-terminal method. Samples which showed an electric resistance reading of zero within the range of measurement error were assumed to be superconducting materials. Table 1 lists samples which exhibited a residual electric resistance like those of common metals and samples which exhibited superconductivity. As will be apparent from this Table, the samples having a silicon content of 2.0 to 40 atomic % had super conductivity, while no superconductivity was observed in the samples having a silicon content falling outside the above-mentioned range. The resistivities at room temperature of tungsten films which exhibited superconductivity were about 100 to 200 μΩ.cm, which were about 20 times as high as the resistivity values of corresponding bulk materials but sufficiently low as the resistivities of materials for electrodes and wirings. In addition, these films are so easily patterned by dry etching that they are suitable as the materials of fine electrode and wirings of semiconductor devices. All these samples showed a Tc of 4.4 to 4.7 K when examined by raising the temperature thereof from 4.2 K. It is also recognized that tungsten films containing certain amount of silicon could be formed by CVD method using WF 6 where Si 2 H 6 , SiH 2 Cl 2 and other silicon-containing reaction gases were used instead of SiH 4 . TABLE 1__________________________________________________________________________Deposition conditions Film characteristics Composition total film resistivitywaferWF.sub.6 SiH.sub.4 N.sub.2 + Ar pressure temp. time thickness (room temp.) Si O F Resistivity (4.2K)No. sccm sccm sccm torr °C. min mm μlcm % % % μΩ · cm__________________________________________________________________________1 30 1190 12 500 149 1.5 1.0 0.30 130.22 40 1180 12 700 60.2 1.5 1.1 0.37 55.33 60 1160 9 667 64.7 1.6 0.86 0.36 60.04 80 1140 236 567 106 2.0 0.90 0.31 superconductivity (˜0)5 120 1100 733 217 3.5 1.0 0.38 superconductivity (˜0)6 160 1060 6 933 214 16.1 1.0 0.27 superconductivity (˜0)7 240 980 433 163 40.0 1.0 0.28 superconductivity (˜0)8 80 30 1190 0.65 12 500 10.0 0.20 1.1 0.31 6.09 40 1180 12 767 13.8 0.27 1.0 0.32 7.210 60 1160 9 733 16.1 0.29 1.1 0.23 8.311 80 1140 354 600 16.8 0.40 1.0 0.33 10.212 120 1100 1167 365 4.0 2.8 0.27 superconductivity (˜0)13 160 1060 6 933 205 13.6 0.88 0.29 superconductivity (˜0)14 240 980 800 257 43.1 0.64 0.27 250.1__________________________________________________________________________ While the thin tungsten films containing silicon were formed by the low-pressure CVD method using WF 6 and SiH 4 as the reactive gases in this embodiment, investigations were also made of a case of forming a film by sputtering. Simultaneous sputtering of a silicon substrate with tungsten and silicon was effected by colliding Ar + ions simultaneously against a tungsten target and a silicon target while keeping a silicon substrate at room temperature to form a tungsten film containing 5.0 atomic % of silicon on the above-mentioned substrate. The electric resistance at 4.2° K. of the tungsten film was measured to find out whether it exhibited superconductivity. It was recognized from that examination that such a film did exhibit superconductivity. Furthermore, it was determined that a tungsten target containing silicon opposed to two different targets, could be used to form such a thin superconducting film by sputtering. Thus, it was confirmed that a superconducting film can be obtained through film formation according to sputtering, in addition to the CVD process. It was also confirmed that impurities, such as oxygen (O) and fluorine (F), contained in tungsten had no grave influences on the Tc and the like of a superconducting film as can be seen in Table 1 which shows no such influences, for example, even when the oxygen (O) content was in the range of 0.86 to 2.8 atomic %. It was further confirmed that tungsten can be used as the material for superconducting electrodes and wirings even when it contains at least one element out of the group of transition metals such as titanium, ruthenium and rhenium and other elements such as carbon and germanium in an amount comparable to that of oxygen (about 3 atomic %). Next, a description will be made of another embodiment according to the present invention while referring to FIGS. 1a to 1c. This embodiment is concerned with a case where tungsten films containing silicon were used as the electrodes and wirings of a silicon semiconductor device. As shown in FIG. 1a, a field oxide film 2 was first formed on a p-type silicon (100) substrate 1 (2-5Ω.cm) by a method as employed in a customary process for producing a semiconductor device, followed by ion implantation of arsenic ions. Thereafter, the resulting structure was heated at 900° C. for 20 minutes to form an n + -type doped region 3. Subsequently, a tungsten film 4 containing 5.2 atomic % of silicon and having a thickness of 300 nm was formed by the low-pressure CVD method using WF 6 and SiH 4 as the source gases. The unnecessary portions of the film 4 were removed by well-known photo-lithography to be patterned into an electrode and wiring. Either where the adhesion of the film 4 to the field oxide film 2 is insufficient, or where a barrier metal is necessary between the film 4 and the n + -type doped region 3, a barrier metal film such as a TiN film or a TiW film may be preliminarily formed below the tungsten film 4 by sputtering deposition , CVD, or the like. Thereafter, as shown in FIG. 1b, a phosphosilicate glass (PSG) film 5 having a thickness of 900 nm was formed by the low pressure CVD method, heated at 700° C. for 30 minutes, and then subjected to customary photo-lithography to form a through hole of 0.5 μm in diameter on the tungsten film wiring 4. Thereafter, a tungsten film 4' containing 5.2 atomic % of silicon was further formed by the low-pressure CVD method using WF 6 and SiH 4 , and patterned into a wiring according to customary photoetching. The conditions of the formation of this film 4' were the same as those of the formation of the first tungsten film 4. The patterning of the film 4' was effected by reactive ion etching using SF 6 , which is a method most generally employed in patterning of tungsten and molybdenum films. It was confirmed that the above-mentioned method can be employed to pattern tungsten or molybdenum films containing 0.2 to 40 atomic % of silicon without any trouble at all to form electrodes and wirings of semiconductor devices. As demonstrated in this embodiment, customary processes for producing a silicon semiconductor device can be employed to form not only monolayer electrodes and wirings but also multilayer electrodes and wirings made of tungsten containing silicon. It was confirmed that the electrode and wirings 4 and 4' made of tungsten containing silicon could be used as superconducting electrodes and wirings when the semiconductor device was cooled to 4.2 K. While only the tungsten film electrode and wirings have been demonstrated in the foregoing embodiments, at least one kind of film selected from among a group including an aluminum film, silicide films respectively derived from aluminum, tungsten, molybdenum and titanium, a polysilicon film, and a TiN film, which are used in common semiconductor devices, can be combined with a tungsten film as mentioned above to form a laminated film, which is then formed into electrodes and wirings. It was recognized that molybdenum containing an equivalent amount of silicon can be used instead of the aforementioned tungsten containing silicon to secure the same level of superconductivity, so that it can be used to form superconducting electrodes and wirings for a semiconductor device. The electrode and wiring of the present invention must be cooled to a given low temperature in order to be used in a superconducting stage. Thus, a semiconductor device provided with electrodes and wirings according to the present invention is cooled by cooling means using liquid helium. Various means, including contact of liquid helium with a cooling fin provided on the rear side of a semiconductor device, can be employed as the cooling means using liquid helium. For example, provision of cooling means as employed in cooling a Josephson device gave good results. As has been described in detail hereabove, in accordance with the present invention, fine electrodes and wirings capable of exhibiting superconductivity above, 4.2° K. can be formed using tungsten or molybdenum having an excellent adaptability to processes for producing a semiconductor device. According to the present invention, customary low-pressure CVD and sputtering, which have heretofore been employed, can be employed to facilitate thin film formation and patterning capable of withstanding heat treatments at high temperatures in succeeding steps. Thus, the present invention is superior from the viewpoints of economy and efficiency.

4y

BACKGROUND OF THE INVENTION The prior art relating to auxiliary locking devices for door locks to insure unauthorized use of the same pertinent to the present invention is generally typified in U.S. Pat. Nos. 1,206,601, 1,917,973 and 2,883,849. Each of these patents disclose a base plate secured about the keyhole to be protected with a hole provided therein aligned with the same and a cover plate pivotally or slidingly co-operating with the base plate to cover the keyhole and means locking the said plates to one another. The keyhole is thereby covered and cannot readily be tampered with. SUMMARY OF THE INVENTION The present invention relates to a lock security device generally of the type described above but differing therefrom in its simplicity of construction and especially in the means for locking the cover plate to the base plate. To this end aligned openings are provided in the plates and the locking means is inserted therein and the locking fingers provided therein are moved outwardly into corresponding openings provided in the base plate under the control of a key for securely maintaining the same therein. The locking means comprises a cylinder with the locking fingers normally disposed in the interior thereof and a key retained therein until the same is turned to move the fingers outwardly and release the key from the retaining means. Therefore the cylinder and key can be carried by an authorized person as a unit with the key locked therein until the same is to be used and thus the key cannot be lost by separation. Additionally, the security device provides a further safety feature in that when the locking cylinder is in place its outer surface is flush with the top of the cover plate and thereby does not present any exposed surfaces which can be engaged by a tool to permit the same to be pried away therefrom. These and other objectives and advantages of the invention will become more apparent from the following description and drawings. DESCRIPTION OF DRAWINGS FIG. 1 is a view showing the security locking device positioned over the keyhole to be protected. FIG. 2 is a view showing the cover plate pivoted to expose the keyhole; FIG. 3 is a sectional view showing the mounting details of the device taken on line 3--3 of FIG. 2; FIGS. 4 and 6 show the details of the locking mechanism of the device in its locked and unlocked position, respectively; FIG. 5 shows the locking cylinder and the locking mechanism associated therewith, and FIG. 7 shows an exploded view of the locking cylinder and its key actuator with respect to the plate receiving openings. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT With reference to FIG. 1, the security device of the invention is designated generally by the reference numeral 10. As seen the device is comprised of a base plate 11, which can be of any general configuration, having acentrally disposed raised planar area 12 having an opening 13 of the same general configuration as the keyhole KH disposed in the door D in order that access can be had thereto. The keyhole KH controls the security lock SL from the outside of the door D. The plate 11 is secured to the door D by fasteners S placed in openings 14 disposed about the edge of the plate. A cover plate 15 is pivotally secured as at 16 to the base plate 11 which can be moved to a position to expose the keyhole as in FIGS. 2 and 3 to a position wherein the same is totally covered as shown in FIG. 1. Both the base plate 11, 12 and cover plate 13 are provided with openings 17, 18 having diametrically opposed slots 17a, 17a and 18a, 18a all of which are in alignment when the plate is in its covering position. The opening 18 is countersunk at 19 for reasons to become apparent hereinafter. A locking means designated generally as 20 is inserted into the openings 17, 17 to secure the plates 11, 15 to one another to thereby prevent unauthorized access to the keyhole KH. As seen in FIG. 7, the locking means 20 is comprised of a substantially closed cylinder 21 having a base 22 and a circular top 23 with the top defining an opening 24 providing access to the interior of the cylinder 21. The top 23 is of greater diameter than the cylinder body 21 having a flange 23a having opposed lugs 23b, 23b depending therefrom and extending along the periphery thereof. A locking mechanism 24 is disposed with the cylinder and is rotatably secured to the post 25 which is anchored to the base 22. The post 25 is centrally disposed in the cylinder and has its free end 26 terminate adjacent the opening 24. With reference to FIG. 5, the locking mechanism 24 is seen to be comprised of an elongated plate 27 having a slotted recess 28 at each end thereof receiving a locking pin 29 fixedly disposed therein by a rivet 30 or the like at substantially a right angle to the plate 27. As seen the cylinder 21 has two openings 31, 31 disposed in its wall with one each being in alignment with the pins 29. A tubular key 32 having a bit 32' controls the locking mechanism 24 and is normally retained with the cylinder 21 by the provision of an angled wire 33 having one end 34 secured to the base 22 and its free end 35 positioned over an abutment 36 fixedly connected to the top of the elongated plate 27. A slot 37 is provided in the abutment 36 and receives the bit 32' and as is apparent when the pins 29, 29 are in their retracted position the key bit 32' is positioned beneath the free end 35 of the wire and therefore cannot be removed. FIGS. 6 and 4, respectively, depict the operation of the locking pins 29 and as seen in FIG. 6, the pins are retracted therein due to the fact that the bit 32' of the key 32 is disposed under the wire 33 when the user turns the key 32, the bit 32' clears the wire 33 and causes the elongated plate 27 to turn due to the bit 32' being held captive in the slot 37 of the protuberence 36, and thereby cause the pins 29, 29 to move outwardly through the openings 31, 31 into aligned openings 31a, 31a provided in the plate 12. The cylinder 21 is therefore locked in place securing the cover plate 15 to the base plate 11, 12 and the key 32 is readily removable as the same has cleared the retaining wire 33. The keyhole KH is now totally covered and cannot be readily tampered with. In use and as seen in FIG. 2, the person availing himself of the device of the present invention locks the security lock SL by the security key SK in known fashion by inserting the same through the base plate opening 13. After locking, the cover plate is moved downwardly as shown by the arrow A until the openings 17 and 18 are aligned and the locking means 20 is placed therein by inserting the lugs 23b, 23b into the slots 17a, 18a to thereby prevent rotation thereof. At this point, the captive key 32 is turned causing the locking pins 29, 29 to move outwardly as explained hereinabove into the co-operating openings 31a, 31a thereby locking the cylinder in place. The key is then removed and the lock SL is protected from entry. To gain access to the lock SL the above steps are reversed. While the fastening means S are shown as engaging and holding the base plate from the inside of the door in order to prevent the same from being tampered with from the outside thereof, it is considered apparent to reverse the same and have the fastening means hold the plate 11 in place from the front of the door.

4y

BACKGROUND OF THE INVENTION (1) Field of the Invention This invention generally relates to an exhaust gas cleaning device for diesel engines of motor vehicles and more particularly relates to a device having filter means capable of physically catching carbon particles or the like (hereinafter referred to as exhaust particles) contained in the exhaust gas and means for burning and removing periodically the caught exhaust particles, thereby regenerating the capability of the filter means. (2) Description of the Prior Art Exhaust particles in the exhaust emissions of diesel engines contain considerable amounts of combustible substances, such as carbon particles or the like, as well as other harmful substances. Hitherto, various kinds of devices have been proposed and used for catching such combustible particles by using an appropriate filter element and then burning and removing the caught particles in order to regenerate the capability of the filter element. Especially, a method is conventionally known for providing electric heaters on the surface of the filter material to ignite the exhaust particles attached thereto and to introduce the energy thus released to the inside area of the filter to burn the exhaust particles accumulated therein. In a conventional exhaust gas cleaning device having electric heaters, the heating elements are directly attached to the upstream end face of the filter member in order to easily burn the exhaust particles accumulated therearound. Under such an arrangement of the heater elements, when the trap case is subjected to engine vibration, since the trap case is directly connected to the exhaust pipe of the engine and therefore the engine vibration is easily transmitted thereto, the heating elements and the front face of the filter may scrub each other, which results in all of these elements being worn. Finally, the heating elements may be broken or a considerable gap may be formed between the heating elements and the front face of the filter, which makes the burning of particles difficult under the preset power, since the preset power is predetermined on the basis of the condition that the heating elements always contact the filter material. SUMMARY OF THE INVENTION An object of the present invention is to provide a cleaning device for exhaust particles of a diesel engine capable of overcoming the defects mentioned above. Another object of the present invention is to provide a cleaning device for exhaust particles of a diesel engine, in which device durability and safety are increased. According to the present invention, there is provided a cleaning device for exhaust particles of a diesel engine comprising: a trap case provided in a flow conduit for the exhaust gas; a filter material disposed in the trap case so that carbon particles or other exhaust particles contained in the exhaust gas can be caught in the filter material when the exhaust gas is passed through the filter material; an electric heater comprising a plurality of heating elements spread over the upstream end face of the filter material so that the exhaust gas passes through the areas between the plurality of heating elements; and means for supporting the plurality of heating elements so as to maintain a predetermined small gap between the heating elements and the upstream end face of the filter material in the direction of the exhaust gas flow, at least a major part of the supporting means being made of heat-insulating material. Appropriate electric power should be given to the heating elements so as to readily ignite the exhaust particles accumulated on the front or upstream face of the filter material over the predetermined small gap. The electric heater element may comprise a plurality of heating wires or rods each extending in parallel to the upstream end face of the filter material, and the supporting means may comprise a plurality of heat-insulating arms extending in parallel to the upstream end face of the filter material, each arm having a plurality of transverse grooves through which the heating wires or rods pass. According to an embodiment of the present invention, the supporting means further comprises spacer cap insulators arranged along the arms, each spacer cap insulator having a plurality of transverse grooves corresponding to the grooves of the arms to define holes into which the heating wires or rods are inserted when the spacer cap insulator is attached to the corresponding arm. According to another embodiment, the supporting means further comprises insulator supporting rods, each arm having a longitudinal recess over the plurality of grooves thereof and each insulator supporting rod being arranged through the recess of each of the arms to restrain the heating wires within the respective grooves of the arm. Each insulator supporting rod may consist of a heatproof stainless steel rod and a ceramic insulator tube into which the rod is inserted. According to a further embodiment, each arm has a plurality of transverse dovetail grooves into which insert members, each having a shape corresponding to the dovetail groove, are fixedly fitted, and each insert member has a groove cooperating with the dovetail groove to restrain the heating wire or rod therewithin. According to still another embodiment, each arm comprises two insulating arm halves each having a plurality of corresponding transverse grooves, and each pair of grooves of the respective arm halves are differently inclined with respect to each other so as to define respective through holes into which the heating wires or rods are inserted when the two arm halves are united. According to still a further embodiment, each transverse groove of the arm has a substantially L-shaped cross section consisting of a groove portion extending perpendicular to the longitudinal direction of the arm and a notch portion extending in parallel thereto from the bottom of the perpendicular groove portion so as to form a hook, and the heating wire or rod is inserted into the notch portion after being stressed or tensioned toward the opposite side of the perpendicular groove portion. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a cross-sectional view of a trap case or exhaust gas cleaning device according to the present invention; FIG. 2 is an enlarged view of the arrangement of the electric heating elements taken along line II--II in FIG. 1; FIG. 3 is an enlarged view of a main portion indicated by III in FIG. 1; FIG. 4 is a perspective view of a first embodiment of heater supporting means used in the present invention; FIG. 5 is a plan view of the supporting means shown in FIG. 4; FIG. 6 is a perspective view of a second embodiment of heater supporting means used in the present invention; FIG. 7 is a plan view of the supporting means shown in FIG. 6; FIG. 8 is a perspective view of a third embodiment of heater supporting means; FIG. 9 is a perspective view of a fourth embodiment of heater supporting means; FIG. 10 is a plan view of the heater supporting means shown in FIG. 9; and FIG. 11 is a perspective view of a fifth embodiment of heater supporting means. DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring now to FIG. 1, a trap case 1 is located at an appropriate position in an exhaust flow conduit 2, in which exhaust gas of a diesel engine flows in the direction shown by the arrows. The trap case 1 may be, however, located at the downstream area of or near to a collecting portion of an exhaust manifold (not shown). The trap case 1 may also be formed integrally with the exhaust manifold by a means such as molding. In the trap case 1, a trap material or filter element 3 and an electric heater 5 are provided. Any suitable ceramic foam known in the art or other similar ceramic materials can be used as the filter material 3. In other words, the filter material 3 is a three-dimensional mesh structure through which exhaust gas can be freely passed, and the exhaust particles contained in the exhaust gas can be trapped or caught in the mesh structure. At the upstream side of the filter material 3, the electric heater 5 is supported by a spacer supporting means 10 so that it is spaced from the front or upstream face of the filter material 3 by a small gap G, as can be seen in detail in FIG. 3. In order to reduce the consumption of electricity, it is advantageous to arrange the heater 5 so that the gap G is as small as possible, provided that the heater 5 does not come into contact with the filter material 3 when the engine vibrates. As is shown in FIG. 2, the electric heater 5 comprises a plurality of, e.g., six heater elements or wires 8A to 8F which are arranged along coaxial circles. This arrangement of heater elements is only an example, and various other shapes and arrangements are possible. In FIG. 2, the heater 5 or heater elements 8A to 8F are supported by a circular-shaped supporting insulator or ceramic member 11 mounted by its peripheral portion on a flange 1a of the trap case 1 by means of a plurality of bolts 18. The supporting insulator 11 has six arms 13 extending radially from the center thereof and arranged at equidistant angles. Each heater element 8A to 8F is supported between a radial arm 13 of the insulator member 11 and a gap spacer member 17. Various embodiments of spacer supporting means for rigidly securing the heater 5 to keep the gap G spaced from the front or upstream end face of the filter material 3 will now be described in detail with reference to FIGS. 4 through 11, each showing portions of the radial arm 13 and the gap spacer member 17. In the embodiment shown in FIGS. 4 and 5, the arm 13 has a plurality of transverse grooves 19, the number of which corresponds to the number of heater wires passing therethrough. After the heater wires are placed in the respective grooves 19 of the arm 13, the ceramic spacer cap insulator 17 also having a plurality of grooves 21 corresponding to the arm grooves 19 is fixedly attached to the arm 13 by means of an adhesive, such as a heatproof inorganic adhesive or other commercially available adhesives so that the heater wires are secured in the holes defined between the respective grooves 19 and 21. As can be seen in FIG. 5, the thickness t of the spacer cap member 17 at the grooves 21 provides a gap G between the filter member 3 and the heater 5. FIGS. 6 and 7 illustrate a second embodiment of supporting means, in which the supporting insulator or arm 23 also has a plurality of transverse grooves 25 which are, however, deeper than the grooves 19 of the arm 13 of the first embodiment shown in FIGS. 4 and 5. The arm 23 also has a longitudinal recess 27 formed over all of the transverse grooves and perpendicular thereto. After the heater wires are placed in the respective grooves 25 of the arm 23, a supporting rod 29 is fixedly attached to the arm along the longitudinal recess 27 by means of a suitable adhesive, such as the one mentioned above. The supporting rod 29 may advantageously consist of a heatproof stainless steel rod 29a and a ceramic or insulator tube 29b into which the rod 29a is inserted. It should be noted that such a supporting rod 29 is more advantageous than a rod consisting of ceramic material only in regard to strength or durability in the case of shock or vibration. It is sufficient if the ceramic tube 29b exists only in the wire-bearing area of the supporting arm 23. In this embodiment, the diameter d of the supporting rod 29 provides the small gap G, as is illustrated in FIG. 7. FIG. 8 illustrates a third embodiment of supporting means, in which the supporting insulator or arm 31 has a plurality of dovetail grooves 33 into which insert members 35, made of suitable material, such as alumina ceramic or heatproof stainless steel, and having corresponding dovetail shapes, are fitted. Each insert member 35 is formed with a groove 39 for the heater wire 8A. In this embodiment, each insert member 35 can be fixedly inserted into each groove 33 by the dovetail engagement, and, therefore, any other fixing means such as an adhesive can be omitted. However, in order to reliably secure the insert member 35 to the groove 33, it is advantageous to use any suitable adhesive, such as a nonorganic adhesive, or to form any suitable claws or stoppers (not shown) to prevent the insert member 35 from coming out of the dovetail groove 33. In this embodiment, the thickness t' of the insert member 35 at the groove 39 provides the gap G shown in the figure. FIGS. 9 and 10 illustrates a fourth embodiment of supporting means, in which the supporting insulator or arm 41 consists of two insulator arm halves 41a and 41b each having a plurality of corresponding grooves 43 and 45. Each pair of corresponding grooves 43 and 45 are inclined differently as is shown in FIGS. 9 and 10, the groove 43 being inclined in the longitudinal direction of the arm half 41a and the groove 45 being inclined perpendicular to the longitudinal direction of the arm half 41b. After the heater wire 8A is inserted into the grooves 43 and 45, the corresponding arm halves 41a and 41b are united as is shown in FIG. 10 so that the common open passage of the grooves 43 and 45 is blocked and the heater wire 8A can no longer be moved rightward in FIG. 10 but is restrained in a predetermined position. In this embodiment, the depth d' of the grooves 43 and 44 provides the small gap G as is shown in FIG. 10. FIG. 11 illustrates a fifth embodiment of supporting means, in which the supporting insulator or arm 51 has a plurality of substantially L-shaped grooves 52 each consisting of a groove portion 53 extending perpendicular to the longitudinal direction of the arm 51 and a groove or notch portion 54 extending in parallel thereto from the bottom of the perpendicular groove portion 52 to form a hook. The heater wire 8A is inserted into the notch portion 54 after under being stressed or tensioned in the direction indicated by the arrow P so that the heater wire 8A is prevented from being removed from the notch portion 54 of the groove 52. The arm 51 and the heater wires are advantageously arranged so that the direction of expansion of the heater wires corresponds to the direction P when heater wires are subjected to heat expansion. In connection with this, if the heater wires are arranged as is shown in FIG. 2, the insulator arm should be so placed that the notch portion 54 is located radially outward of the groove 53. In this embodiment, the thickness t" of the insulator arm 51 at the hook formed by the notch portion 54 provides the small gap G.

4y

This is a continuation of application Ser. No. 07/680,699 filed on Apr. 4, 1991, and issued as U.S. Pat. No. 5,260,678 on Nov. 9, 1993. BACKGROUND 1. Field of the Invention This invention relates generally to combined ballasts and wiring harnesses for fluorescent-lamp fixtures; and more particularly to so-called "leadless" ballasts that directly carry connectors for attachment to wiring in the fixtures. 2. Prior Art Fluorescent lamps require relatively high starting voltages, and in many cases electrode heating. These are supplied by a combination of transformer coils, capacitors and thermal-overload circuit breakers, all usually potted together in a metallic enclosure familiarly known as a "ballast". Some so-called "electronic ballasts" have much smaller, lighter coils and relatively much more extensive electronic circuitry. These units may be potted, or their components may be coated only lightly ("dipped") or not at all. A typical indoor fluorescent-lamp fixture or luminaire is an elongated, narrow structure with an even narrower, shallow casing that extends the length of the fixture for mounting of fluorescent-lamp sockets and for housing of the ballast and the fixture wiring. As the ballast usually fits within (or sometimes upon) one of these narrow, shallow casings, the ballast too is usually made relatively long, narrow and shallow. The ballast has its own enclosure, usually made of two sheet-metal pieces. One piece is die-cut and then bent to provide two generally vertical side walls, a generally horizontal floor, and conventionally a vertical wall at each end of the enclosure respectively. A second, flat piece (with mounting holes for attachment to the casing) forms a separate coverplate. In this document we shall refer to the ballast by the nomenclature just established--in which the flat coverplate is considered to be the top of the ballast, and the horizontal panel that is made integrally with the side and end walls is considered to be the bottom. Ballasts are in that orientation when potting material is poured into the cans for potting the components, and usually or at least often are also mounted in that way. In any event we shall use this terminology for purposes of definiteness--although, for descriptive purposes, in many patents and other documents ballasts are shown inverted with respect to the convention just described; and ours too can be so oriented in use. General practice in the fluorescent-lighting industry for more than a half century has been to provide wires that extend from within the ballast through a grommet or strain relief in each end wall, respectively. Some of these wires connect with a lamp socket mounted at each end of the lamp fixture, respectively; and others of the wires connect with the input power leads. The ballast wires sometimes are made the correct length to just reach the sockets in some particular lamp model, and sometimes are made shorter, for attachment to other wires--often called the "wiring harness"--which then extend the remaining distance to the sockets. Representative patents exemplifying this standard configuration include U.S. Pat. No. 2,489,245 to Sola, U.S. Pat. No. 2,595,487 to Runge, U.S. Pat. No. 3,360,687 to Riesland, and U.S. Pat. No. 3,655,906 to Robb; as well as Canadian Patent 751,052 to Kukla. Adherence to this basic form of ballast wiring has remained dominant in the industry despite issuance of many patents proposing seemingly reasonable variations. U.S. Pat. No. 2,487,468 issued in 1949 to Shirley R. Naysmith for one such variation--in which the wires from each end of the ballast terminate in respective half-connectors; these plug directly into mating half-connectors in lamp-socket assemblies, at the ends of the fixture respectively. The Naysmith patent proposed that "all the wiring within the luminaire may be completed by merely plugging together the cable-carried receptacles to the fixed lamp holders." The inventor envisioned that fixture assembly would be thereby rendered so easy that "ballast units may be completed and pretested by the ballast manufacturer, the lamp holders by the lamp holder manufacturer, and shipped to the [installation] location in suitable lots without passing through the factory of the fixture manufacturer, thereby avoiding freight and handling, and the parts can be readily assembled on the job . . . " Naysmith's device is not a "leadless" ballast. In U.S. Pat. No. 3,514,590, M. David Shaeffer proposed (1970) a leadless ballast, made to plug into a printed-circuit board that would--with a single backing plate--replace both the casing and the wiring of a fluorescent-lamp fixture. The lamp sockets as well as the plug-in ballast were to be supported at the underside of the printed-circuit board. Shaeffer's objective was that the entire fixture be amenable to assembly quickly and without the use of tools. U.S. Pat. No. 3,569,694 of Oscar L. Comer posited in 1968 that a ballast-can coverplate be extended longitudinally beyond one end wall of the can, and that an array of laterally oriented connector pins be fitted to a vertical bracket on the baseplate extension. Short wires passed to these pins through the nearby end of the ballast can; and the pins in turn mated with a complementary array of laterally oriented female contacts mounted to the casing of the fixture. This unit thus might be called "almost leadless". The plug-in concept was carried to its logical extreme in U.S. Pat. No. 4,674,015 of Daniel R. Smith, which in 1987 taught that the entire ballast should be plugged bodily sideways into a large receptacle in the casing. In Smith's leadless design, contact tabs on the interior wall of the receptacle engage mating contact tabs on the side wall of the ballast can. U.S. Pat. No. 4,729,740 issued in 1988 to Crowe et al., showing a small printed-circuit board within the ballast can--and supporting all the other components in the can. In particular the internal circuit board supported at each end of the assembly a respective electrical connector for attachment of the several individual leads of a wiring harness leading to each half (i.e., each end) of the fixture respectively. Crowe's ballast too is thus a leadless configuration. From Crowe's drawings it appears that his invention is intended primarily for use as one of the previously discussed "electronic ballast" types. His text, however, by its general language seems to suggest that the invention has broader application to more-conventional "magnetic" ballasts as well. At each end of the assembly, Crowe's connector fits against the end wall of the can--except where the connector protrudes through a window cut in the end wall--and is longitudinally stabilized by grooves in the connector that receive the cut side edges of the window. We refer to this kind of mounting, in which the connector edges define a groove that makes a sliding engagement with the edges of a window in the end wall, as a "picture frame" mounting. The firm with which we are associated, MagneTek Universal of Paterson, N.J., has introduced a leadless electronic ballast under the trademark "LUMINOPTICS" and covered by U.S. Pat. No. 4,277,728. It has a full-length circuit board generally analogous to Crowe's--but mounted to a flat plate that becomes the cover, rather than to the U-shaped body. It also has a second board that is much shorter and mounted vertically to the full-length board. The LUMINOPTICS ballast is not potted, although some of the components are individually dipped. It has various modern features including a connection for computerized control, and a manual dimmer control. A poke-in eight-contact wiring connector is provided at each end of the ballast, respectively. Each connector is mounted to a corresponding end of the full-length circuit board, accessible through a port in the associated end wall. A groove defined in each of these connectors engages an inset flange formed at the bottom of the port, to stabilize the connector to the U-shaped body. A separate two-pin standard connector is installed in one end wall for power input. Another leadless ballast design that uses an internal connector is disclosed by Burton et al. in U.S. Pat. No. 4,916,363 (1990), assigned to Valmont Industries, Inc. of Nebraska. Here the internal connector receives the wiring-harness wires either individually or in a connector-like carrier that organizes the wires into an array, but the internal connector is not mounted in the picture-frame style as in Crowe--and in fact is not in an end wall of the can at all. Instead the internal connector is mounted in a transverse slot that extends all the way across the width of the bottom of the can, about a quarter or a third of the distance along the can from one end. At the side of the internal connector which faces toward that nearer end, the bottom of the can is formed in a shallow bevel that makes the connector face accessible for insertion of the wires. The ballast can of Burton et al. is also formed with an inset longitudinal ledge (or, more strictly speaking, upside-down ledge) along each of its lower longitudinal corners. Each ledge is used for routing of wires from the connector in both longitudinal directions to the lamp sockets, and at each end is provided with "clamp portions"--apparently formed integrally with the ballast can--adapted to be bent over toward the inset ledge, to keep the wires on the ledge. Because of the ledges along each lower corner, the cross-section of the can has a step at each corner. On one side of the transverse slot, the connector-surfaces abut or fit against inside surfaces of the can all the way down both sides and across the bottom, including the corner steps. Therefore the connector too is notched or stepped at its lower corners. At the other side of the transverse slot in the can, a flat surface of the connector abuts the cut-off edge of the slot. As will be seen, these several surfaces abutments at three different orientations pose at least a challenge to attainment of effective seals during potting. Another modern development in leadless ballasts, apparently not now the subject of an issued patent, is the line of ballasts available from the Valmont Electric Company (a subsidiary of Valmont Industries) under the commercial designation "XL Series". An XL ballast has a single half-connector mounted in one end wall of the ballast can, and formed as a receptacle. That wall-mounted receptacle receives another half-connector, configured as a jack, which terminates the wiring harness. The receptacle fits within, and protrudes slightly through, a window cut in the end wall of the can; while a flange around the receptacle is provided to press against the inner surface of the end wall, all around the window. In the Valmont XL Series ballasts the receptacle carries a row of male contact pins, which are the tips of rectangular-cross-section metal strips leading from an intermediate terminal block. The terminal block is positioned about an inch inside the can, and is apparently held generally suspended (before potting) in that region by electrical leads soldered to contacts on the electrical components. In the XL Series configuration, during potting, two small ratchet-style locking tabs--one at each end of the half connector, respectively--hold the receptacle flange against the inside of the wall. These tapered snap tabs, based on our own testing of such fasteners, give a better seal than the picture-frame retainers discussed earlier--but here too, at a production-engineering stage prove overly sensitive to the possibility of tolerances adding up adversely. Since the contacts in the receptacle are male, the jack of course carries female contacts; within the jack the female contacts are permanently secured to the ends of the wires in the harness. These wires leave the jack body through a surface that faces the end wall of the can, so that at least those wires which lead to lamp sockets at the same end of the fixture as the jack are bent in a tight "U" shape. Of the several variants discussed above, only the last three seem to have become commercially important. The concept of a leadless ballast does seem to be gaining some ground in the fluorescent-lighting industry. In fact a significant effort has been mounted by Valmont Industries to declare such ballasts--and, mope particularly, the connector and pin configurations of the XL Series--an industry standard. Perhaps the fluorescent-lighting industry could benefit from ballast standardization, but there is no standard yet. We believe that all of the above-discussed variations, including the two Valmont configurations, have important limitations which should be addressed and resolved before settling upon any of them, or even any combination of their features. A few of the known features discussed above--especially the circuit-board mounting used in Crowe and the LUMINOPTICS ballast--appear adequate for some electronic ballasts, which are lighter and produce less vibration. As will be seen, however, such mounting is problematic for other electronic ballasts that do have relatively heavy radio-frequency-interference and power-factor filters, and also for the more-familiar magnetic ballasts, which still constitute by far the greatest fraction of ballast sales. All or most of the remaining limitations seem to flow from inadequate recognition of several major characteristics of the overall process of ballast and fixture manufacturing, distribution, use and replacement. For specific reference we shall state these characteristics in the form of eight numbered "ground rules" for ballast design: (1) The fluorescent-lighting industry is price competitive to an extreme. Profit margins in ballasts are correspondingly small, and production volumes are very high--so that manufacturing-cost advantages of only a fraction of a penny per ballast are likely to be significant. (2) A major factor in ballast manufacturing cost is labor, particularly hand labor. Seconds lost in fussing with assembly or with touchy alignments and the like prior to potting, or later in wiping spilled or leaked potting potting material from the outside of each ballast, translate into major cost components. (3) Material costs of course are also important, and militate strongly against use of additional intermediate components to perform limited functions. For example, the relatively expensive floating intermediate terminal block in the XL Series ballasts apparently is used primarily to obtain effective strain relief of the electrical leads inside the ballast can. (4) Another cost-related consideration is that a ballast connector should be as compatible as practical with already-existing ballast-design and ballast-manufacturing techniques. Some changes in assembly-line equipment and layout or sequence can be very expensive, and as amortized--even over many hundreds of thousands of ballasts--can thereby add significantly to unit cost. (5) Commendable wishes for industry standardization are not the same thing as actual achieved standardization. Any ballast configuration that is offered as a standard must offer users, distributors, fixture manufacturers and ballast manufacturers alike some reasonable means of coping with a protracted period of time during which standardization among manufacturers is incomplete. In addition, regardless of leadless-ballast standardization, it seems unlikely that the industry will achieve complete standardization of fixture lengths, or accordingly of wiring-harness lengths. (6) Any proposed standard ballast must also accommodate effectively an even more protracted replacement or retrofit period. During such a period the new-style ballasts must be used to replace millions of used ballasts of many different configurations--but primarily the long-time standard ones shown in, for example, the Sola, Runge, Riesland, Robb and Kukla patents mentioned earlier. Therefore a ballast connector should accommodate replacement or retrofit of earlier conventional ballasts that have protruding leads. (7) Fluorescent-lamp fixtures intrinsically are roughly handled, knockabout items that must be designed to intrinsically withstand careless handling, and some degree of improper installation. Consumers do not treat fixtures or ballasts as if they were, for example, laboratory instruments or personal computers; therefore it is a mistake for designers to so treat them. (8) Magnetic (and some electronic) ballasts themselves contain heavy components that can generate significant internal forces due to mechanical shock and vibration in shipping and handling. Once in operation they also generate heat and develop forcible vibrations, which often increase with use. Successful ballast designs therefore must avoid not only use of fragile elements, but also elements that when heated or vibrated can damage other nearby standard components (such as wiring). Based upon these ground rules 1 through 8, we shall now comment upon the several ballast variants discussed above. We wish to make clear that all of these devices may serve (or may have served) reasonably well for their intended purposes; the comments that follow will simply show that there remains some opportunity for improvement. The Naysmith design violates ground rules 1, 3, 8 and 8, as it requires a ballast with preattached cables, at least long enough to reach the lamp sockets, and it provides every new ballast with two relatively expensive half-connectors and cables. At the outset, Naysmith's proposed system would thus be prohibitively expensive, in modern terms. Moreover, the connectors and cables of an older Naysmith ballast being replaced are discarded with the old unit, even though the old connectors and cables usually are in perfectly good condition. Worse yet, to use the ballast with an older standard fixture, the expensive connectors and cables must be cut off and discarded at the outset. Even for use with various models of a single manufacturer the design is undesirable. The manufacturer must assemble, and then the distributor must stock, ballasts with several different cable lengths. If the distributor is out of stock for a unit with a short cable, the buyer must settle for a more expensive one with a long cable. The Shaeffer design violates at least ground rules 7 and 8. During handling, installation or replacement the weight of the ballast is likely to be inadvertently struck against the very large, expensive printed-circuit board--incurring the risk of damage to the board. As is well known, such damage is likely to be partially or entirely concealed and is likely to cause an electrical fault of the worst sort--namely, an intermittent one. If proposed as an industry standard, it would also violate ground rules 4 through 6. Here, however, as contrasted with the Naysmith situation already discussed, the difficulty of using Shaeffer's ballast configuration in a conventional fixture would be essentially prohibitive. It is clear that Shaeffer's teachings are not intended to have any compatibility with existing or present standard fixtures. Thus, as he explains, the electrical connections of his ballast terminate in an array of small connector pins in the coverplate. For use with a standard wiring harness, these pins would require some sort of mating connector added to the wire ends--or perhaps a solder joint. Shaeffer does not address these possibilities, for the apparent reason that the connector pins would interfere with mounting of his ballast in a conventional fixture anyway. Plainly, use of that ballast in such a fixture would require far more than use of Naysmith's--i.e., more than merely cutting off and discarding expensive but unused components. The Comer configuration too would violate ground rules 4 through 6, although in degree of incompatibility with earlier fixtures it is perhaps intermediate between the Naysmith and Shaeffer designs. In Comer's unit, some wires do extend out of the can, perhaps three to five centimeters, to his laterally mounted connectors; thus cutting off and discarding the connectors might possibly permit connection by means of wire nuts or the like to the stub wiring. As will be evident, however, making connections to such short wires is difficult or at least awkward and annoying. In the course of the process a growing cluster of wire nuts would develop in a small region adjacent to the end of the can, requiring progressively greater dexterity and care to make each successive connection. Even removal of the Comer connectors and their mounting bracket--if indeed that were feasible without damaging the coverplate--would make available very little additional room for the new connections. In addition Comer's ballast violates ground rules 1 through 3. The additional metal usage for the coverplate extension and connector bracket, and the hand-mounted individual connectors, would probably make Comer's design economically unfeasible. Daniel Smith's ballast violates ground rules 4 through 8, for generally the same reasons as Shaeffer's ballast. If anything, Smith's configuration is more problematic with respect to retrofit: his contact tabs appear probably even more resistant to adaptation for use in older fixtures than Shaeffer's pins. The Crowe ballast is particularly interesting, since it is relatively similar in outward appearance to other modern designs (including the LUMINOPTICS unit). It is also interesting because Crowe's patent contains some important teachings which are followed by one other patented design, but which we regard as incorrect. For most ballasts--more specifically, for magnetic ballasts and those relatively heavy electronic ballasts that have power-factor or radio-frequency-interference filters--the Crowe configuration violates ground rules 7 and 8. During shipping and handling, the weight of the ballast components is likely to crack the internal circuit boards, causing damage even more obscure than that discussed above with respect to Shaeffer's large external circuit board. Crowe's circuit board is even more subject to damage due to vibration. Whether caused by handling damage or vibration, damage to the circuit board in a Crowe ballast is even more likely to be intermittent. His circuit board is more directly coupled to heat developed within the electrical components of the ballast, and therefore more likely to flex during warmup. Flexure might not occur, however, until heat accumulates to nearly a steady-state operating condition, perhaps an hour after the lamp starts. We believe that Crowe's invention also violates ground rules 1 and 2, at least for fully potted ballasts. We have experimented with connectors mounted by a "window frame" kind of mounting, of the general sort employed in Crowe's ballast, and found such mounting unacceptable. Problems with such mounts arise from the generally rough-work nature of the inexpensive sheet-metal forming procedures used in making ballast cans. More specifically, we learned that the sometimes rough sheet-metal edges, and sometimes very substantial curvature of the metal, produced a much higher need for installation force than anticipated. When the window-frame grooves along the connector edge were widened to alleviate this problem in some units, then the fit was rendered loose or sloppy for other units that happened to be smoother or less curved. Hence, if a window-frame mount is chosen to be relatively tight, extra assembly time and cost will often be required to force the connector into place--with caution needed to avoid slips that could cut the workers' hands on the metal edges. These operations could be particularly difficult in a ballast with a circuit board attached to each connector, as in Crowe. On the other hand, if the mount is chosen to be relatively loose, then extra time and cost will often be required to wipe away the potting material that leaks around the edges of the connector in a loose mounting. In especially loose installations, our connectors actually floated upward in the potting material, as that material was poured, leading to what might be called "catastrophic leaks". Thus, in summary, fit is critical in window-frame mounting. Special precautions of course could be taken to hold the connector in place, and perhaps also to press it firmly against the wall during initial stages of pouring the potting material; but these precautions would be unacceptably costly in terms of labor. In Crowe's configuration the connector cannot float out of place because it is secured to the circuit board; but we regard circuit boards as undesirable in most ballasts, for the reasons already discussed. Thus as noted above we consider picture-frame mounting to violate ground rules 1 and 2. Crowe provides connectors that receive discrete leads from the wiring harness individually, rather than grouped leads held in a half connector as in Burton and in the Valmont XL Series. Crowe explains: "One . . . manufacturer has included an electrical connector . . . for interconnection thereto by a mating electrical connector. The disadvantage to having an electrical connector at the end of the discrete wires is that typically the fluorescent fixtures are not sold with a mating electrical connector. Therefore, the manufacturer of the ballast has to include both connector halves which increases the cost of the electrical ballast. Furthermore, the installer . . . must not only replace the ballast but must also terminate the discrete wires of the lighting to the mating half of the electrical connector. When replacing the ballast, the user . . . must buy a ballast which also carries an electrical connector which is matable with the electrical connector of the first ballast installed." For several reasons, we believe that Crowe is incorrect in this teaching. First, he fails to recognize the two enormous benefits of using an external connector, whether prewired by a fixture manufacturer or attached later by an installer of a replacement ballast: (1) After the external connector has once been permanently installed on the wiring harness and the harness tested, all ballast installations thereafter (including both the initial installation and all replacements) are far easier and simpler. (2) More importantly, after the first test of the combined connector and harness, all later ballast installations are also rendered virtually foolproof with respect to correct wire-to-pin correspondence. This latter point is most crucial, since the time required to make individual-lead connections is not merely the time required to plug in a single connector multiplied by the number of leads; to the contrary, great care (entailing extra time) must be taken to ensure that each lead is being connected to the proper contact. Secondly, Crowe overlooks the fact that for new fixtures--when the ballast is sold on an OEM basis to the fixture manufacturer--that manufacturer will be willing to pay for the slight additional cost of the external half connector (partly offset by a small saving in labor cost for wiring and testing), in order to obtain the competitive advantage of being able to advertise especially easy ballast replacement. Thirdly, turning now to use of a new-style leadless ballast for field replacement of older-style ballasts: there is a fallacy behind Crowe's assertion that the user must buy a replacement ballast that "also carries an electrical connector which is matable with the electrical connector of the first ballast installed." What Crowe overlooks here is that, when a ballast meeting all the above-mentioned ground rules is introduced to the fluorescent-lighting industry, there may be greater reason to expect standardization of pin assignments and connector configurations. Thereafter all new ballasts would carry compatible connectors; Crowe's objections would then all die within one generation of ballasts. Fourthly, also regarding new leadless ballasts used as field replacements, Crowe overlooks various possibilities for distributing the external half connector for use in field replacement. At first, of course, for a period of perhaps four to seven years virtually every leadless ballast sold for field-replacement use would require such an external half connector; therefore during that preliminary transitional period it would be simplest to include one external half connector (and its price) with every new replacement ballast. After that, manufacturers could make an external connector available to retailers for distribution separately as an "adapter", either at a nominal price or free upon request. These procedures, if judiciously timed, would limit the manufacturer's added cost to, on average, a small fraction of the cost of one external half connector for each older-style ballast that is replaced. Fifthly, and still as to field replacements, Crowe overlooks the possibility that to "terminate the discrete wires . . . to the mating half" the installer need not necessarily do any mope work than would be required to make individual connections to Crowe's internal connector! That is, the wiring provisions in the external half connector may be made of the poke-in-and-lock type. Stripped discrete leads would then be simply inserted into the rear of the external half connector, just as is the case with Crowe's connector. The poke-in connections would be substantially permanent, but release cams could be included in the half connector for prompt correction of wiring errors. Sixthly, Crowe fails to realize that providing for use of an external half connector is not necessarily the same thing as requiring one. That is, allowing for use of an external half connector can be made compatible with attachment of the wiring harness discrete leads to the can-mounted half connector individually. In other words, the benefits of using an external half connector may be achieved while retaining the user's options to wire replacement ballasts without one. Parts of this strategy are shown by Burton, whose ballast design we shall discuss next. Burton's ballast violates ground rules 1 and 2, because the geometry of the connector and of its centralized mounting is inherently subject to leakage. The reason for this vulnerabilility is that the can and the connector both have steps at their two lower corners. At each step there is one horizontal segment and one vertical segment. In addition there is a third horizontal segment across the floor of the can. If the tolerance of all five of these segment lengths, as established in the sheet-metal forming steps, is not held to perhaps 3/4 millimeter (0.03 inch) or better, potting-material leakage is likely to be substantial. Ballast-can construction, however, for the necessary economies desired according to ground rule 2, is inherently of a coarse character; fine tolerances are rather beyond the norm--at least for a multisegment shape as required by the Burton geometry. This is particularly so if one takes into consideration the great variation of bending properties and resilience in different material lots. Even apart from varying impurity content and the like, normal cold-rolled steel used in ballast cans is typically 0.66±0.08 mm (0.026±0.003 inch) in thickness: that tolerance of nearly twelve percent of course generates large variations in strength, resilience, etc. Either inordinate labor cost must be incurred to hold unusually tight sheet-metal forming tolerances to avoid leakage, or extra labor must be expended in wiping away potting material after pouring. In either event, the Burton configuration also demands extremely careful positioning (or some other sealing technique) to avoid leakage at the abutment between the vertical face of the connector and the straight cut edge along the beveled-floor segment of the can. The Burton ballast also violates ground rule 8, in Burton's provisions for routing wires of the harness from the centrally mounted connector in both directions along the ballast to the lamp sockets. Concededly, Burton's previously described ledges and cable clamps do impose some orderliness upon the wire runs. Presumably this is an effort to avoid damage by pinching of stray leads between the ballast housing and the fixture casing. Burton's solution, however, appears to be counter-productive. To the extent that the character of the clamps can be determined from the Burton patent, they appear to be metallic, and in fact unitary with the other portions of the ballast can. It would seem that using such clamps, likely with sharp edges, to secure wires along the ballast-can ledge actually creates a risk of damage to the wires or their insulation. The significance of such damage will be apparent. Forming the clamps over the wires also represents an undesirable additional manufacturing cost--a violation of ground rules 1 and 3. Furthermore, the clamps make installation or replacement much more difficult. Thus Burton's ballast violates ground rules 1 through 3, and 8. It does demonstrate, however--as mentioned earlier--that a ballast connector may be configured to receive wiring-harness leads either (a) as a group held in a connector, or (b) individually if the connector is unavailable. Burton's wiring-harness carrier 66 serves virtually as a connector body, to hold the individual wires together in a standardized array that matches the contact array of the mating connector in the ballast. The system therefore provides both quick connection and the essential certainty of correct wiring, and so takes a step in the right direction with respect to ground rules 5 and 6. The individual bare-wire ends held by Burton's carrier directly engage poke-in contacts of the connector that is mounted in the ballast. Therefore a person who does not have Burton's carrier can nevertheless insert the bared ends of individual or discrete wires directly into the same poke-in contacts, to attach an older-style fixture (which has no wire carrier) to the ballast. Of course this is not as convenient as using an external carrier or connector body, but is as convenient as any other system for attaching wires individually--i.e., as convenient as earlier conventional systems using wire nuts, or using poke-in systems such as Crowe's. Hence Burton's connection system facilitates field replacement of old-style ballasts, as well as OEM installation. Burton's apparatus shows that the benefit of an external half connector may be kept while retaining the user's option to wire replacement ballasts without one. As Burton's patent fails to mention or even suggest this dual function, however, it is not clear whether Burton obtained this benefit intentionally or inadvertently; furthermore, the specific mechanics of his system are questionable on several grounds, as follows. Burton's system uses poke-in contacts in the ballast-mounted connector. These poke-in wiring connections between the ballast and the wiring harness constitute the entire mechanical system for holding the harness to the connector. That is, the wiring system is required to serve as its own strain-relief system. We consider such a confusion between the functions of electrical contact and mechanical integrity to be relatively undesirable industrial practice, implicating indirectly ground rule 8 above. If excessive withdrawal force is applied to the wires while they are restrained by the poke-in contacts, the tangs inside the poke-in connector may damage the wire ends--either jamming them within the poke-in cavities, or weakening them so that they fail later under vibration, or possibly deforming them so that they cannot later make good contact with the poke-in contacts of another ballast. Burton provides a "release comb" to disengage all the poke-in contacts at once, to allow for removal of the external wires with their attached carrier. This release comb is relatively wide and short, and therefore appears susceptible to cocking and then binding in its guides, particularly if a user attempts to operate it after the ballast has been in operation under typical conditions of heat, accumulating dirt, and vibration for several years. Burton's patent does not state whether the comb is stowed permanently in its guides ready for use in field replacement, or is to be kept nearby for such use. (If the former, the assembly sequencing must be selected to avoid potting the comb; and if the latter, the comb is likely to be lost before it can be used.) Whichever may be the situation, the user must first find the comb and otherwise see to its proper positioning--partially concealed above the wiring carrier. The user must then try to slide the comb longitudinally, relative to the housing, in a short operating recess adjacent to the ballast-mounted connector: the release comb operates in cramped quarters at best. Most drawbacks of Burton's ballast arise at least partly from the centralized location of the connector. We therefore submit that such centralized mounting is undesirable. As has been shown in discussion of the Crowe ballast, however, problems also arise in prior-art efforts to mount a connector at an end (or at each end) of the can. This assertion is validated by consideration of the XL Series ballast, with its end-mounted connector. That ballast appears to violate ground rules 1 through presented above. We shall take these points in order. Within the ballast can, the XL ballast apparently requires an additional, costly intermediate terminal block for strain relief, as well as custom-made and custom-assembled flat metal strips that serve as pins and intermediate connectors. Extra labor--which may appear partly as material cost, if the assembly is bought complete for OEM use--is also required to make connections at both sides of this terminal strip. In potting, the XL ballast relies upon a pair of tapered or ratchet-type snaps to hold the connector flange against the inside of the end wall. This technique relies on controlled deformation of both the plastic snaps and the metal edges. Formed sheet metal, however, is subject to uncontrolled bending or warping, particularly near corners. Rolled and punched sheet-metal construction is inherently coarse. Under these conditions, in our experience, the window will sometimes seem too wide to yield a reliable seal, and sometimes too narrow for the snaps to pass through, with a reasonable amount of force. In either event, the result is additional labor, extra attention for seconds or minutes--to either force the snaps in, or wipe away potting-material leakage later. Tolerances can be controlled to avoid these problems, but the cost of doing so is then objectionable. The XL unit also uses additional current-carrying components, at least within the ballast housing. This too increases cost without clear advantage. As to ground-rule 4, the extra terminal strip in the XL system also requires an additional assembly step, rendering the unit relatively incompatible with a standard assembly line. In addition the extra connection introduces undesirable electrical resistance, which can be significant especially in some so-called "rapid start" filament circuits that operate on as little as three volts. Outside the can, the XL Series ballast fails to answer the challenge posed by Crowe: connection is possible only by means of the external half connector, with no mitigating provision for field replacement. The external half connector does not appear to be of an easy-to-wire (e.g., poke-in) type such as we have described above; and there is no suggestion in the XL Series literature of any arrangement for making the external connectors available to users separately for field replacement. In addition, the previously mentioned reverse wire dress of the external connector can only serve as an invitation to damage during shipping, handling, or field replacement. With that we reach ground rule 7. In view of all the foregoing it appears clear that the prior art has not yielded a fluorescent-lamp leadless ballast, or leadless-ballast-and-harness combination as appropriate to the context, that makes use of an external half connector for its very important benefits while satisfying all of ground rules 1 through 8. A long-felt need of the fluorescent-lighting industry--and of the users of fluorescent lighting--has thus gone unmet. SUMMARY OF THE DISCLOSURE In view of the eight "ground rules" stated above for ballast constructions, at least as long as sheet metal is used for ballast cans, we consider it very important to develop a configuration that is completely compatible or harmonious with the intrinsically rough nature of formed sheet metal. Based on lengthy experimentation with several mounting systems, we have come to recognize more fully how all of the conventional attachment techniques essentially fight the underlying character of sheet-metal fabrication. For example, in addition to the picture-frame and tapered-snap mounts discussed above, we have analyzed or experimented with rivets, pins, and lanced cans (in which thin metal stakes provide guides for a connector body). Through-fasteners generally require unacceptable extra operations; and the lance technique is subject to tolerance problems similar to those of the picture-frame and tapered-snap mounts. Our invention avoids all these problems, by applying the resilience--and generally the roughly defined dimensionality--of the sheet metal to help ease the insertion of a connector, and thereafter to help control its position, rather than opposing those properties as in other systems. Our invention preferably also incorporates other techniques, introduced below, that provide strain relief, accommodate field-replacement problems, etc. Here too, we accomplish these objectives by making the most of what is necessarily present in the ballast--rather than by adding more pieces and introducing more complications. With the foregoing informal introduction, we shall now proceed to offer a somewhat more rigorous discussion. Our invention has several major aspects--some encompassing apparatus, and other aspects encompassing procedures. In a first major aspect of the invention, our invention is, in combination, a ballast and connecting apparatus for use in a fluorescent-lamp fixture. It includes at least one electrical winding, and plural electrical leads operatively connected to the winding, for carrying electrical power to and from the winding. The apparatus also includes a housing or can, that has two generally upstanding side walls, generally enclosing the winding and leads. The housing has two ends. Our reason for saying that the housing "generally" encloses the winding and leads is to make clear that the housing need not enclose the winding and leads hermetically, or even in all directions. For example, as will be seen with respect to some aspects of the invention, the housing--although it has two ends--need not have end walls. The apparatus also includes an electrical half connector disposed at at least one end of the housing. It further includes, defined at each side of the half connector, respectively, an ear that extends laterally into association with one side wall, respectively. Defined in each side wall, immediately adjacent to said one end of the housing, the apparatus includes a cutout notch. This notch is for receiving the connector ear that is associated with that side wall, to retain the connector in place longitudinally at the end of the housing. Finally the apparatus in this first major aspect comprises plural individual electrical contacts formed from or operatively connected to ends of the electrical leads respectively. The contacts are fixed within the half connector, for making electrical connections outside the housing. The foregoing may be a definition of this first major aspect of our invention in its broadest or most general form. Even this broad form of the invention, however, can be seen to resolve several of the prior-art problems which we have discussed earlier. There is virtually no additional cost associated with this aspect of our invention: all the materials are necessarily present in any conventional ballast can which is fitted at one end (or both ends) with a connector. In assembly, the connector is simply placed in position with its ears in the notches, which accordingly cooperate to locate the connector relative to the side walls. The ease of this step is relatively quite insensitive to the accuracy of the sheet-metal cutting or bending--i.e., of fabrication tolerances--within normal industrial practice. No extra step must be added, and no otherwise desirable step must be omitted, to incorporate this procedure into a substantially conventional assembly line. The invention simply makes such a line operate more easily and quickly. Furthermore, once the connector is emplaced the degree of accuracy of its positioning, relative to the walls of the housing, similarly depends very little upon such tolerances. Consequently a good seal can be made between the connector and housing, if desired. In any event the connector is well located relative to the housing, for purposes of placement in a jig or fixture for further processing--such as, for example, attachment of a coverplate and other features that permanently secure the connector in place. With regard to field-retrofit use, the ballast according to this first aspect of our invention in its broadest form is readily interchangeable with earlier ballasts that have integral leads--provided only that suitable arrangements are made for attachment of the external wires in the fixture to the ballast connector. Such arrangements will be taken up again later in this document. The simple shapes and interfitting of parts, in the first aspect of our invention as so far described, also introduce no fragility. Furthermore they introduce no new element that could damage other parts of the ballast. This first aspect of our invention even in its broadest form therefore satisfies all of the earlier-introduced ground rules 1 through 8. This economical, simple geometry thus turns to advantage the inherently coarse character of the ballast-can construction, to yield (1) easy, stable and accurate positioning of the connector relative to the can walls, and (2) a good seal around the connector, including the areas near the ears and notches, for potting. We prefer, however, to practice the first aspect of our invention with certain other features or characteristics that appear to optimize its performance and benefits. For example, we think it best that each notch be defined in an upper corner of the housing, at the top edge of the corresponding side wall. In such a construction the connector simply hangs "by its ears" from the notches in the top edges of the side walls, in a particularly stable way. We also prefer that each ear extend upward to substantially the level of the top edge of the corresponding side wall. The first aspect of our invention is particularly advantageous when the winding, leads, and internal portions of the half connector are potted within the housing by pouring of liquid potting material that solidifies around them. In this context, the notches cooperate with the ears to locate the connector firmly against the end of the housing and deter the potting material, while that material is liquid, from leaking out of the housing. We also prefer to make the housing so that it has at least one end wall, at the same end of the housing as the half connector; and to define an orifice in the end wall of the housing. In addition we prefer to dispose the connector at least partly within the housing at the orifice, and firmly against the end wall to deter the potting material from leaking through the orifice. In that preferred structure it is advantageous if the electrical connector protrudes through the orifice. Such a configuration serves to further retain the half connector in place and deter the connector from floating, in the liquid potting material, out of position. In conjunction with the first major aspect of our invention--particularly when there is a plurality of electrical wires, extending through the fixture but substantially all outside the ballast housing--we prefer to provide a second electrical half connector. This second half connector is for holding the outside electrical wires, for making electrical connection between wires and corresponding contacts in the first half connector, respectively. This combination preferably includes hook means, with a ratchet action, for locking the second half connector in engagement with the housing or in engagement with the first half connector. It also preferably includes manually operable release means, for releasing the hook means to disengage the half connectors from each other. Several other preferred features or characteristics, which we consider it desirable to practice in conjunction with the first aspect of our invention, will appear from later portions of this document. In particular, we prefer to practice all of the several major aspects of the invention together. A second major aspect of our invention is a procedure for fabricating a fluorescent-lamp ballast. As will be seen, the procedure is closely related to the first (apparatus) aspect of the invention. The procedure comprises the steps of: (1) preparing at least one electrical winding, with plural electrical leads operatively connected to carry electrical power to and from the winding; (2) preparing a housing, for enclosing the winding and leads, that includes two generally upstanding side walls, the housing having two ends; this housing-preparing step includes the substep of defining a cutout notch in each side wall, immediately adjacent to an end of the housing; (3) forming from or operatively connecting to ends of the electrical leads, respectively, a plurality of individual electrical contacts; (4) preparing an electrical half connector that defines, at each side of the half connector respectively, an ear for extending laterally into association with one side wall, respectively; this connector-preparing step includes fixing the contacts within the half connector for use in making electrical connections outside the housing; and (5) then positioning the winding and leads within the housing and positioning the electrical half connector at one end of the housing, with the ears inserted into the cutout notches, respectively. These five steps may constitute a description or definition of the second major aspect of our invention in its broadest or most general form. This method satisfies all the previously discussed ground rules for ballasts, generally as pointed out in connection with the first major aspect--but with particular emphasis on the assembly-line and related labor-cost considerations of ground rules 4, 3 and 1. In particular--because of the notches introduced in step (2) and ears introduced in step (4) of the procedure just described--the critical step (5) is characterized by ease, simplicity and effectiveness in assembly that are not available in any prior assembly method. As with the first aspect, however, we prefer to practice the second aspect of the invention with certain other characteristics or steps that optimize the beneficial results of the procedure. For example, we prefer that the housing-preparing step comprise biasing the side walls outward; and further comprise the additional step of--after the positioning step--moving the side walls inward, against the outward bias. We also prefer that the procedure further comprise two subsequent steps: (a) while the side walls remain inward, pouring liquid potting material into the housing around the winding, leads, and internal portions of the half connector; and (b) then permanently securing the side walls moved inward. In this event we prefer that, during the pouring step, and thereafter while the potting material remains liquid, the notches cooperate with the ears to retain the half connector in position at the end of the housing and deter the potting material from leaking out of the housing. In addition we consider it preferable that the housing-preparing step comprise forming the housing with at least one end wall, at the same end of the housing as the half connector, and defining an orifice in the end wall of the housing. Here we prefer that the positioning step comprise disposing the half connector at least partly within the housing at the orifice, and firmly against the end wall to deter the potting material from leaking through the orifice. In this last-mentioned instance, it is preferred that the connector-disposing step further comprise inserting the electrical connector to protrude through the orifice. Such protrusion is advantageous to further retain the half connector in place--and deter it from floating, in the liquid potting material, out of position. We also find it advantageous if the housing-preparing step comprises biasing the side and end walls outward. In this case it is best that the procedure further comprise the additional step of--after the positioning step but before the pouring step--moving the end wall and side walls inward, against the outward bias. The end wall then longitudinally engages the connector and closely captures the ears in the notches; and the side walls closely approach edges of the end wall. The result is that leakage of the potting material through the orifice, or through the notches, or between the end wall and the side walls, is deterred. In the method as just described, we prefer that the wall-moving step comprise placing the housing, with the winding, leads and connector, in a fixture that holds the side and end walls inward. We also prefer to include the subsequent step of permanently securing the walls moved inward--as, for example, by affixing a cover that engages and holds the walls. Before the walls are moved inward, and before the pouring step, the end wall resiliently engages the connector longitudinally. In this way it facilitates assembly by retaining the half connector in place. We prefer that the half-connector-preparing step comprise forming each ear so that in the positioning step the ears will extend upward to substantially the level of the top edge of the corresponding side wall. This deters the liquid potting material from leaking out of the housing above the ears. A third major aspect of our invention, usable independently of the others but preferably practiced in conjunction with them, is--like the first--a combination of a ballast and connecting apparatus for use in a fluorescent-lamp fixture. This combination includes at least one electrical winding; and plural electrical leads operatively connected to the winding, for carrying electrical power to and from the winding. It also includes an electrical half connector. The combination further includes plural individual electrical contacts, formed from or operatively connected to the electrical leads respectively. The contacts are fixed within the half connector, for making electrical connections between the leads and such a fixture. Material of the half connector is displaced by fracture, substantially without flow, into or around the leads or the contacts to hold the leads or the contacts within the half connector. In this way strain relief is provided for each contact without using any additional component. From what has already been said about this third major aspect of the invention, it can be seen to significantly enhance compliance with the previously enunciated ground rules for ballasts--particularly the first three rules. This aspect of our invention provides necessary strain relief at zero material cost. It requires just one simple mechanical assembly step, one that is readily automated. That step occurs in a preliminary part of the assembly procedure, when there is ample room for placement of the necessary equipment and manipulation of the partial assembly. Plastic materials are most suitable for use in molding a half connector for use in our invention. Such materials are conventionally displaced, in plastic-welding processes and the like, so that they merge or blend with electrical-wire insulation. In conventional procedures, such displacement has been used for general positioning purposes and for strain relief. By our above phrase "without flow" we mean to distinguish such known uses. To be effective for our purposes, the material of the half connector must deform by processes that may be described by words such as "snap", "break", or "fracture", rather than "flow"; that is, the material must be displaced while it is relatively brittle. It must not, however, be too brittle--lest an entire region of the structure near the displacement region shatter, destroying the structural integrity of the half connector and also thereby introducing various other problems. One alternative way of articulating this third aspect of our invention is to say that the displacement is by fracture substantially without heating (rather than without "flow"). The reference point here is the ordinary range of room temperatures in a mechanical processing or assembly area. That is to say, even though an assembly-line facility may be heated--as for comfort of workers--our invention may still be practiced in such a facility. Displacing material of the half connector without further, localized heating in such a facility would be within the scope of our invention as here described. There is still another way of articulating this third major aspect of our invention. This other mode of expression does not rely upon the concepts of fracture without flow, or without heating; however, it is more specific than the first two as to mechanics. It relates to a form of the third aspect of the invention that we have found to be outstandingly effective. In this formulation, or articulation, the apparatus includes--in addition to the winding, leads, and contacts mentioned earlier--an electrical half connector that defines a plurality of passageways. The passageways are for receiving the plural leads, respectively, near their ends; each passageway has a respective interior wall. Material of the half connector is displaced to form plural pieces of said material that are wedged between the leads and the corresponding passageway walls, respectively. They thus serve to hold the leads within the second half connector, so that--as before--strain relief is provided for each lead without using any additional component. We prefer that the pieces be broken from the half connector at an angle less than thirty degrees, such as very roughly fifteen degrees, off the perpendicular to the passageways, respectively. Each piece accordingly has a corresponding angled shape, which particularly facilitates and enhances the wedging action described above. In a fourth major aspect of our invention, related to the third, analogous strain-relief results are obtained by fracture and displacement of material in a half connector--but an external one, that mates with the half connector which forms part of the ballast. Thus our invention can be used in either half connector, or both. A fifth major aspect of our invention is, in combination, a ballast and connecting apparatus for use in a fluorescent-lamp fixture that has lamp sockets. The combination is for attachment to such sockets selectively either (a) by discrete electrical wires attached to the ballast individually or (b) by a group of electrical wires held in an electrical half connector, if available, that is external to the ballast. The combination includes at least one electrical winding; and plural electrical leads operatively connected to the winding, for carrying electrical power to and from the winding. It also includes an internal electrical half connector adapted to mate with such an external half connector if available. In addition it includes plural individual electrical contacts, operatively connected to the electrical leads respectively, and fixed within the half connector for making electrical connections beween the leads and the electrical wires. Each contact is a female element of resilient conductive material, formed into a generally circumferential conductive socket. Each socket directly receives, generally encircles, and makes a good wiping contact with a bared end of an electrical wire, respectively. The sockets as a group are arrayed to receive bared wire ends held in an external connector of a certain configuration. Connection therefore can be made either with such an external connector or without one. Thus the combination is useable for replacement of old ballasts even if an external half connector is not available. Important to this fifth major aspect of our invention is the circumferential or cylindrical character of the female contacts, and the smooth wiping contact that they make with the bared wire ends. This refinement preserves the advances introduced by Burton--while avoiding wire damage that otherwise could lead either to failure in service or to serious difficulty in connecting a new ballast several years later. As before, the foregoing may constitute a definition or description of the fifth major aspect of our invention in its broadest or most general form, but we prefer to incorporate other elements or characteristics. In particular we prefer that the combination also include the external electrical half connector--including an external connector body. That body, if included, holds all of the electrical wires with the bared metal ends in relative positions to directly engage corresponding contacts in the internal half connector. In addition, the external connector body slides smoothly into and out of engagement with the internal half connector. The wires slide smoothly into and out of engagement with the contacts, respectively. They do so without interference by any device that locks wires individually into engagement with individual contacts. We prefer also to include some means, not acting through the wires or contacts individually, for releasably securing the body of the external connector to the internal half connector. Advantageously such means include at least one ratchet-like hook fixed with respect to one of the half connectors, for releasably engaging an element that is fixed with respect to the other half connector. All the foregoing operational principles and advantages of the present invention will be more fully appreciated upon consideration of the following detailed description, with reference to the appended drawings, of which: BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a partly schematic perspective or isometric view, taken from below, showing a preferred embodiment of a ballast and connecting apparatus according to our invention, together with lamp sockets of a fluorescent fixture. This embodiment has a connector at only one end of the ballast can. FIG. 2 is a similar view showing another preferred embodiment that has a connector at each of the two ends of the ballast can, respectively. FIG. 3 is an isometric or perspective view of one end of a partly formed ballast can for use in either the FIG. 1 or FIG. 2 embodiment. The sheet-metal blank for the can is fully die-cut and punched, but only the sides are bent up--and they are resiliently biased laterally outward. FIG. 4 is a like view of the same can at a later stage of forming, with the end wall of the can bent up and resiliently biased longitudinally outward--and with a horizontal end segment of the can also bent to extend longitudinally outward from the vertical end wall. That longitudinally extending horizontal end segment is drawn partially broken away, for a better view of the vertical end wall. FIG. 5 is a like view showing the internal half connector preliminarily positioned. FIG. 6 is a like view showing the walls moved inward against their outward bias to bring the half connector to its final position and potting compound being poured. FIG. 7 is a like view of a coverplate (shown inverted) for the embodiment of FIGS. 1 through 6. FIG. 8 is a side elevation showing the coverplate in place and holding the walls inward, on the finished can of the FIG. 1 embodiment. FIG. 9 is a plan view of the same finished can, taken along the line 9--9 in FIG. 8--i.e., with the horizontal main panel of the coverplate cut away--and showing the components within the can. FIG. 10 is an elevation in longitudinal section, showing the internal and external half connectors mated, in one preferred embodiment of our invention. FIG. 11 is a like view for another preferred embodiment of our invention. FIG. 12 is an outside end elevation of the receptacle, or internal half connector, of the FIG. 10 embodiment. FIG. 13 is a side elevation of the same receptacle. FIG. 14 is an inside end elevation of that receptacle. FIG. 15 is a top plan, partly in longitudinal section, of the same receptacle. FIG. 16 a bottom plan of the same receptacle. FIG. 17 is a front (i.e., inward-facing) end elevation of the jack, or external half connector, of the FIG. 10 embodiment. FIG. 18 is a rear (outward-facing) end elevation of the same jack. FIG. 19 is an elevation in longitudinal section, taken along line 19--19 in FIG. 17, of the same jack. FIG. 19A is a like detail view, considerably enlarged, of a hook-tip portion of the same jack. FIG. 19B is a like view, similarly enlarged, of a contact-seating and -retaining portion of the same jack. FIG. 20 is a top plan, partly in longitudinal section, of the same jack. FIG. 21 is a bottom plan of the same jack. FIG. 22 is an outside end elevation, similar to FIG. 12, of the receptacle in another preferred embodiment of our invention, similar to that of FIG. 10 and FIGS. 12 through 16. FIG. 23 is a top plan view, greatly enlarged, of a female contact in a preferred embodiment of our invention. FIG. 24 is a side elevation of the same contact. FIG. 25 is a rear end elevation of the same contact. FIG. 26 is a cross-sectional elevation, taken along the line 26--26 in FIG. 24 and even further enlarged, of a portion of the same contact. FIG. 27 is a cross-sectional elevation, taken along the line 27--27 in FIG. 24, of the same contact. FIG. 28 is a side elevation, in longitudinal section along the line 28--28 in FIG. 23 and further enlarged with respect to FIGS. 23 and 24, of a portion of the same contact. FIG. 29 is an end elevation, very greatly enlarged and showing details of a coined insulation-gripping or conductor-gripping tab, in the same contact. FIGS. 30 and 31 are somewhat schematic front and side elevations of multiple-punch tooling for displacing material of a multiple-lead connector, to provide strain relief in accordance with a preferred embodiment of our invention. A representative connector body is also shown. FIG. 32 is a perspective view, more schematic but greatly enlarged--showing a single lead or wire, and a single tool, that form part of the same connector and tooling. FIG. 33 is a schematic longitudinal section showing initiation of material displacement in the same connector by the same tool. FIG. 34 illustrates provision of strain relief for an insulated wire or lead, showing completion of material displacement for the same connector and tool. FIG. 35 is a side elevation showing one preferred embodiment of the tool of FIGS. 33 through 34. FIG. 36 is a view similar to FIG. 32 for the same tool and for a similar connector that is another preferred embodiment--but drawn without the tool, and showing a preformed inset or recess at the site where material is to be displaced. FIG. 37 is a view similar to FIG. 33, but for one form of the FIG. 36 embodiment. FIG. 38 is a view similar to FIG. 34 but for another form of the FIG. 36 embodiment. FIG. 39 is a view similar to FIG. 36, but for yet another preferred embodiment. FIG. 40 is a fragmentary perspective or isometric view, similar to FIG. 32, showing a representative connector and one lead, before material displacement, in another preferred embodiment of the strain-relief aspects of our invention. FIG. 41 is a cross-sectional elevation of the FIG. 40 embodiment after material displacement. FIG. 42 is a side elevation, in longitudinal section, showing still another usage of our slug lock. Unlike FIGS. 32 through 41, FIG. 42 illustrates provision of strain relief for a contact that terminates a wire or lead--rather than for the wire or lead directly. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Lamp sockets 1, 2 (FIG. 1) may be considered as part of the context or environment of our invention, or to the extent recited in certain of the appended claims may be elements of the inventive combination. The same is true of the external half connector 70, the power supply wires 6, the external wiring 3, 5 from the sockets 1, 2 to the ballast 10/40, and the cross-connections or common wiring extensions between the parallel-wired sockets 1. The system of FIG. 1, with its single connector 50/70, includes sockets 1, 2 for two lamps; and the connector has one unused wiring position. FIG. 2 illustrates a system with two connectors--one at each end of the ballast--and with sockets 1, 2, 1', 2' for four lamps. This FIG. 2 system includes additional direct ballast-to-socket wires 3', 5' and additional cross-connections 4'. If the ballast is an electronic type, the external wiring may include an added wire 7 to a computer or to a manual control for light intensity or the like--thus using all nine wiring positions in one connector 50/70 that carries the input power and control connection. The connector at the other end of this ballast, however, has three unused positions. If justified by production volume, connectors with fewer wiring positions may be substituted for those having some positions unused, in both FIGS. 1 and 2. A countervailing consideration is the cost of the added tooling required. As shown in FIGS. 1 through 9, the ballast can or housing 10/40 is made up of two main parts: a lower structure 10 and a coverplate 40. Each is made from a single formed piece of sheet metal respectively. The lower structure 10 includes two generally upstanding side walls 11, continuous (along a corresponding fold 15 at each lower edge) with a pair of transitional angled panels 13, respectively. Each of these angled panels 13 in turn is continuous (along a respective fold 14) with a common central floor 12. Continuous with the floor 12, along a transverse fold line 24 at each end, is an end wall 21. In the illustrated embodiment, each end wall 21 is in turn continuous along another transverse fold line 32 with an end segment 31, and along a pair of longitudinal fold lines 28 with a pair of short side tabs 27, respectively. After assembly, as seen in FIGS. 1 and 4, both of the latter longitudinal fold lines are generally vertical, while the end segments 31 are generally horizontal and extend longitudinally. As explained elsewhere in this document, we believe that our invention encompasses embodiments having no vertical end wall 21, no side tab 27, and no horizontal end segment 31. The side tabs 27 (when present) then extend longitudinally from the side edges 28 of the end walls 21, along the outside surfaces of the side walls 11 respectively. Analogous side tabs 47, much longer than those of the end walls 21, extend downward from fold lines 48 along the long edges of the coverplate 40--also along the outside surfaces of the corresponding side walls 11. For best inside clearance each side panel 11 is enlarged or "bellied out" in an area that is below (as in FIG. 1; or within, as in FIG. 8) a tapered step 11' formed in the sheet metal of the side panel. The step 11' may meander somewhat arbitrarily, as suggested by comparison of FIGS. 1 and 8. The end segments 31 are preferably formed with holes 35 for use in connection to the coverplate 40 (FIG. 7), at matching holes 45 in that plate--as by fasteners 38 (FIG. 8). The end segments 31 and 41 of both the lower structure 10 and the coverplate 40 are slotted 34, 44 for attachment by suitable fasteners to a luminaire (not shown). Die-cut into each side wall 11, at each end 17 of the side wall 11 where a connector is to be installed, is a respective notch 18/19. Each notch includes a vertical edge 19, longitudinally inset from the corresponding side-wall end edge 17; and also includes a longitudinal bottom edge 18. In the preferred embodiment illustrated, each notch 18/19 is cut out of the upper corner of the corresponding side wall 11 (although, as explained elsewhere, that limitation is not believed to be necessary). Thus the notch has no upper edge as such, and the longitudinal bottom edge 18 of the notch is simply inset or down-set below the upper edge 16 of the corresponding side wall 11. Die-cut in each end wall 21 (when present) that will carry an internal half connector 50 is a respective orifice 22/23. The orifice has an upper, relatively large rectangular portion 22, and a smaller slot or recess 23 communicating with the bottom center of the large portion 22. In the preferred embodiments that are illustrated, the internal half connector 50 is mounted substantially just inside the corresponding end wall 21. We use the term "substantially" here to allow for the slight protrusion of an outward-projecting circumferential flange 52 from the internal half connector body 51/58, through the large upper portion 22 of the end-wall orifice 22/23. The external half connector 70 includes a body 71, to which all the external wires 3, 5, 6 are connected. In the preferred embodiments of FIGS. 1, 2, 5, 6, 8 and 10, the internal half connector 50 is a receptacle and the external half connector 70 is a jack. Thus, when the external half connector 70 is mated with the internal half connector 50, the forward tip of the external half 70 is inserted into an outward-facing antechamber 56 formed within and by the circumferential flange 52. In other preferred embodiments, however, the opposite relationship may be used, as shown in FIG. 11. In either event, a hook 72 that projects from the external half connector body 71 then protrudes through the small recess portion 23 of the orifice 22/23 in the end wall 21, and into a small secondary cavity 57 (see FIGS. 5, 6, 8, 10 and 11) formed with the internal connector body 51/58. In assembly of the preferred embodiments illustrated in FIGS. 1 through 10, typically the lower structure 10 and coverplate 40 are first die-cut from flat sheet metal. Then the side walls 11 and transitional angled panels 13 are bent upward from the floor 12 to the orientations generally shown in FIG. 3. As previously mentioned, the end wall 21 is continuous with the floor 12, the end segment 31 and the short side tabs 27--along respective fold lines 24, 32 and 28. Those fold lines thus form part of the demarcation of the end wall 21. The remaining demarcations of that wall are formed by substantially vertical cut side edges 26, below the short tabs 27, and angled cut lower-transitional edges 25. The end wall accordingly has a double-trapezoidal shape, whose two angled lower edges 25 after bending lie generally adjacent to the cut edges of the two angled transitional panels 13. As this bending process is completed, but before the metal break or other tooling is released, the long-fold angles 14, 15 are such as to add up to substantially a right angle; in other words, each of the walls 11 is then substantially perpendicular to the common floor 12. Similarly the side tabs 27 are then bent to a right angle, or slightly past a right angle, relative to the end walls 21. Finally right angles are formed along a short fold line 24 where the floor 12 is continuous with the end wall 21, and at a longer fold line 32 where that wall 21 is continuous with the end segment 31. Because the metal is resilient, however, when the tool releases the metal all these bends spring open slightly from their final angles as formed. Then the side walls 11 and end wall 21 all angle slightly outward from the vertical, relative to the floor 12. The overall result of the bending action and the reaction just described appears in FIG. 4. In FIGS. 4 and 5 the springback has been drawn exaggerated to permit a more definite view of the consequent clearances. In FIGS. 4 through 8, the end segment 31 is drawn partially broken away at 37 for a clearer view of relationships between other parts. FIG. 4 shows, in particular, a gap between the end edges 17 of the two intermediate angled panels 13 and the nearly adjacent angled lower edges 25 of the end wall 21, respectively. This gap is narrowest just adjacent to the floor folds 14, and widest at the outer corners formed by the end-wall angled edges 25 and vertical edges 26. Also shown is an even wider gap between the end edges 17 of the two side walls 11 and the adjacent side edges of the end wall 21. (These side edges are formed, as earlier noted, by cut edges near the bottom of the end wall 21, and then by folds 28 nearer the top of the end wall 21.) This gap continues to increase from the bottom toward the top, due to the outward angles of both the end wall 21 and side walls 11. The short side tabs 27, folded from the end-wall 21 side edges 28, project longitudinally next to the outside surfaces of the side walls 11, respectively--and in particular next to the notches 18/19 cut in the upper end corners of the side walls 11. Thus the tabs 27 partially obstruct the openings constituted by the notches 18/19. FIG. 5 illustrates the next assembly step, which is to drop roughly into place the internal half connector 50, with its attached internal leads 91 and their associated electrical components 92 through 95 (FIG. 9). In FIG. 5 one of the side tabs 27 is drawn broken away at 29, for a clearer view of the relationships between the parts of the internal half connector 50 and the sheet-metal parts already described. The internal half connector 50 has a body 51/58, and an end-wall-abutting lip 62 (FIGS. 10 and 11) that extends upward from the forward or outward portion 58 of the half-connector body 51/58. The lip 62 restrains the body 51/58 from falling forward through the end-wall orifice 22, while allowing the previously mentioned circumferential flange 52 to protrude slightly through the orifice. The internal half connector 50 also has a pair of ears 55 that extend upward from the flange 62, and thus indirectly from the body 51/58. When the internal half connector 50 is preliminarily emplaced, these ears 55 slide loosely downward into the corresponding notches 18/19--roughly guided, laterally, by the short side tabs 29 at both sides of the assembly. Optionally if desired such guidance could be enhanced by deforming the side tabs 27 inward in small dimples 27' (FIG. 3). We have found assembly quite satisfactory, however, without that additional feature. As the bottom surfaces 54 of the ears 55 approach the horizontal cut bottom edges 18 of the notches 18/19, the forward tip of the outward-projecting circumferential flange 52 slips easily through the orifice 22 and protrudes very slightly as shown in FIG. 5. At this stage the positioning of the connector is very preliminary and rough, and only shown by FIG. 5 in a very representative way. For example, in one extreme situation the ears may rest squarely in one or both notches, with the rearward edge 53 of an ear closely juxtaposed to the vertical edge 19 of the corresponding notch--as may appear from the portion of FIG. 5 that shows the near corner. Instead the ears may be slightly canted horizontally--as may appear from the portion of the illustration showing the far corner, where the vertical edge 19 of the far notch 18/19 is visible to the left of the far ear 55. In either event the ears 55 and flange 62 remain somewhat spaced away from the inside surface of the end wall 21. The forward edge of the wall that defines the secondary cavity 57 also remains spaced somewhat inward from the end wall 21, behind the cut edges of the small recess portion 23 of the orifice 22/23. FIG. 5 shows all these relations clearly. Alternatively, as another extreme case, it is particularly easy for the entire connector body to fall forward toward the end wall 21, so that the ears 55, flange 62, and secondary-cavity wall 57 rest lightly against the inside surface of that wall 21. Moreover the connector 50 can come to rest preliminarily in any of a great variety of positions intermediate between the two extreme orientations just described. Successful practice of our invention does not depend upon orienting the connector 50 in any particular one of these conditions--provided only that (1) the ears 55 are somewhere in the notches 18/19 and between the side tabs 27, and (2) the entire periphery of the forward-projecting flange 52 is either started through the orifice 22 in the end wall 21, or sufficiently well aligned with the orifice 22 at the instant when the next stage of assembly begins to start through it readily. This independence of any fine prealignment, or any other sort of fussing with the pieces, is a particularly valuable aspect of our invention. As previously pointed out, and as we shall shortly explain in terms of the very lenient tolerance requirements for the structures involved, this independence is not significantly traded off against fabrication costs but rather is a natural product of the unique geometry. FIG. 6 represents the next assembly stage. Here pressure 101 is applied laterally inward, and pressure 102 is applied longitudinally inward, on the side and end walls 11, 21 respectively. This pressure 101, 102 is commonly provided by inserting the assembly bodily into a jig--sometimes denominated a "pouring fixture"--which returns the walls to their previously substantially upright or perpendicular positions as obtained duping bending. For purposes of this document, elements of the pouring fixture can be regarded as represented by the arrows 101, 102. In these positions the gaps illustrated and previously discussed in connection with FIG. 4 are all substantially closed up. At the same time the connector 50 is progressively forced square, erect and flat against the end wall 21. More specifically, the ears 55 are captured between a pair of opposing jaws--each formed by a notch vertical edge 19 at one side and the inside surface of the end wall 21 at the other. As these jaws come into near-parallelism, and approach a spacing that closely approximates the thickness of the ears 55, the jaws force the ears into line--straightening the ears in the notches--and the rest of the connector body follows suit. While the lower structure 10 and the connector 50 are held firmly in this condition, potting material is poured as at 103 into the structure 10, and around the connector, wires and associated components 92-95. The coverplate 40 is then affixed as in FIG. 8, so that the long side tabs 47 retain the side walls 11 inward--and the fasteners 38 hold the end segments 31 and thereby the end walls 21 inward. The assembly 10/40/50 etc. can then be removed from the pouring fixture and set aside for cooling and solidifying of the potting material. It can now be more fully appreciated why successful practice of the foregoing aspects of our invention is relatively independent of fine adjustments and fussy prealignment. For one thing, the forward-projecting flange 56 need not fit through the orifice 22/23 very closely: the seal between the connector 50 and the end wall 21 is formed by flat-abutting parts all around the orifice. Further, the notches 18/19 may be slightly taller than the ears 55, provided that the fit is close enough to permit only very little leakage. This is not a severe constraint, for the notches are only a small fraction of an inch wide and any resulting gap is backed up at least esthetically by the side tabs 27. The only fit between the connector and the can that is to any extent critical is the match between the widths of the notches 18/19 and of the ears 55. Here a relatively close tolerance is required, the ears preferably being if anything slightly narrower than the notches, as it is this fit that ensures a close abutment between the flat-abutting parts 55, 62, 57 and the end wall 21, as previously mentioned--to prevent leakage at the orifice 22/23. This is true particularly around the small lower recess portion 23 of the orifice, where the path to potting material is relatively short. This sensitivity can be minimized if desired by provision of a small peripheral flange 68 (FIGS. 12 through 14, and FIG. 16) around the hook chamber 57, to lengthen the leakage path. Similarly such a structure can be continued in a like flange 69 (FIGS. 12 through 14, and FIG. 16) along the bottom of the body 58, at both sides of the hook chamber 57. This latter flange 69 even further reduces leakage along the bottom edge of the large upper section 22 of the orifice 22/23. We consider it within the scope of our invention to cut the notches 18/19 at positions, along the end edges 17 of the side walls 11, other than those illustrated and above discussed. In some ballast-can configurations, for example, the notches can be slightly lower--with an upper edge (not illustrated) of each notch formed just below the top edges 16 of the side walls. In that arrangement, because of clearances arising from springiness of the various walls, the same general geometry and procedure can still be employed for insertion of the connector--adjacent to and protruding through the end wall. Another alternative is to omit the metal end wall 21 entirely, and to form the connector so that it fills the space at the end of the longitudinal walls and floor 11-13. Now it can be appreciated that notches 18/19 cut into the end edges 17--about halfway, or even more, down those edges--locate the connector effectively relative to the panels 11-13. This locating action is sufficient for positioning of the lower structure, half connector, and internal electrical components within a pouring fixture. Later, coverplate tabs or the like secure the side walls 11 inward to maintain the closure, as in the geometry illustrated and earlier discussed. To reduce the number of segments along which the connector edges and metal panels have to match, in the configuration under discussion, the angled lower side panels 13 can be eliminated if desired--and the side walls 11 and the floor 12 instead can be run all the way outward and downward to join each other in bottom corners. FIGS. 10 and 11 show interfitting between the two half connectors 50, 70 and the end wall 21--for two alternative forms of the connectors, which correspond to use of female contacts in the external and internal half, respectively. These drawings also show how we prefer to provide male and female contacts for use in the connectors. Details of the connector and contact features appear in FIGS. 12 through 29. As shown in FIGS. 10 and 11, a standard internal lead of a ballast--or a standard fluorescent-fixture wire--can serve as a male pin for one or the other half of the connector. In FIG. 10, an internal lead 91e is stripped to provide a bared end 96e that is used as a male pin; and a female contact 110e, crimped to the bared end 8 of an external harness wire 5, receives that male pin 96e when the connector halves mate. In FIG. 11 it is the external harness wire 5 that is stripped, providing a bared end 8 that serves as a male pin; and it is the internal lead 91e whose bared end 96e is crimped in a female contact 110e. The female contact is substantially greater in diameter than the male pin; therefore whichever half connector carries the female contact has a contact chamber that is of relatively large diameter necessarily. If the mating half connector were designed to fit within the female-contact-carrying half, surrounding the female contact, then the female-contact-carrying half would require a contact chamber of even greater diameter. Use of such a large, open chamber would increase the likelihood of inadvertent damage to the female contact. Accordingly we prefer to make whichever half connector carries the female contacts 110e, etc., serve as the male half of the connector--i.e., a jack 71 or 61e' etc. That male half connector is then inserted into the other half connector 58' or 71', which carries the male pin 96e or 8, etc.; that other half is therefore configured as the female half of the connector--that is, a receptacle. As FIG. 11 shows, however, a simple construction in which the internal half connector is a jack 61e' results in substantial protrusion of that half connector from the end wall 21. If this protrusion is considered undesirable in terms of risk of damage to the jack 61e', etc., the jack may be--at somewhat greater cost--recessed within the end wall 21. To explicitly represent the above-discussed ballast-can geometry (FIGS. 1 through 9) with use of the FIG. 11 embodiment, or with that embodiment modified by recessing as described in the preceding paragraph, certain revisions would be required in the details of FIGS. 1 through 6, and FIGS. 8 and 9. The connector flange 52 shown in those drawings would have to be redrawn--either protruding further as a group of elongated contact chambers 61, each like the chamber 61e' in FIG. 11; or having such a group of chambers 61 recessed as just described. Rather than substantially duplicating several of those drawings, we hereby incorporate by reference the features of the FIG. 11 embodiment, as alternative forms, into those other drawings of this document that show connector features. Hence those other drawings are to be considered as representing all three connector geometries--i.e., those of FIG. 10, FIG. 11, and the described modification of FIG. 11. In both FIGS. 10 and 11 the lower part of the end wall 21 forms a lip 21', which constitutes the edge of the lower recess portion 23 of the orifice 22/23. This lip 21' extends slightly above the bottom of the hook-receiving chamber 57 formed in the internal half connector. For passage of the hook tip 73 into the chamber 57, the hook 72 can be deflected so that its tip 73 moves to a raised position 73' as represented in the phantom line in FIG. 10. A user can accomplish this deflection by squeezing the shank 72 of the hook upward toward the external half connector 71. Alternatively, a user can simply push that half connector into place in the internal half. During this process the angled forward surface 73' (FIG. 19) of the tip 73 operates as an inclined plane against the lip 21', forcing the hook 72/73 upward in the manner of a ratchet. In either event, once the tip 73 has passed the lip 21' the hook 72 can be allowed to spring back downward so that the lip 21' captures the hook tip 73. The hook 72 and thereby the external half connector 70 are thereby retained in place until a user again operates the hook tip 73 to its upper position 73'--this time necessarily by squeezing the shank upward--for removal. FIGS. 10 and 11 are taken along the longitudinal centerline of the assembly. Therefore the lead, wire and contact--and the connector chambers in which they are held--shown in FIGS. 10 and 11 represent the central wiring positions, of the several positions preferably provided in connectors according to our invention. As shown in FIGS. 12 through 16, an internal half connector (receptacle) 50 forming part of a preferred embodiment of our invention is segmented into nine contact-mating chambers 61 in a row 61a through 61i. These chambers 61 (or 61a through 61i) are cylindrical, and are recessed within the previously mentioned antechamber 56. FIGS. 17 through 21 show that our preferred external half connector (jack) 70 is similarly segmented to form nine contact chambers 74 (or 74a through 74i). When the jack 70 and receptacle 50 are connected together, these contact chambers 74 of the jack 70 are first received in the antechamber 56 of the receptacle 50. The antechamber 56 serves to prealign the jack contact chambers 74 and guide them into the contact-mating chambers 61. This guiding function is enhanced by fitting of rails 88, along the outboard sides of the jack 70, into mating grooves 61' at both sides of the antechamber 56 (and then continuing into the two outboard contact-mating chambers 61a, 61i). Leads 91 (or 91a, 91b, and 91d through 91i, FIG. 10) from the electrical components of the ballast are introduced into the receptacle 50 from the Opposite or rear end, through insulated-lead holding chambers 63. The leads 91 are secured within the holding chambers 63 by the strain-relief provisions of our invention--discussed elsewhere in this document--or if preferred by conventional plastic-welding techniques, or other means. The stripped ends 96 of the leads 91 are further inserted into bared-lead guide channels 64. From these channels 64 the stripped ends 96 of the leads 91 extend forward into the contact-mating chambers 61. There each stripped lead end 96, serving as a male contact or pin, engages a female contact 110--as shown in FIG. 10 for the central chamber 61e. For best pin alignment we extend the bared-lead guide channels 64 as far forward as possible. To accomplish this we form a central bulge in the rear wall 65 (or 65a through 65i) of each contact-mating chamber 61, as seen in FIGS. 13 and 15. Each bulge 65 is separated from the cylindrical surface of its chamber 61 by a thin annular space. This space receives the annular tip 84 (FIG. 17, and FIGS. 19 through 21) of the corresponding contact chamber 74 of the jack 70. The centerlines of the nine wiring positions 61-64-63 in the receptacle 50 are spaced apart from one another by just enough to preserve thin walls 67 (FIGS. 12 and 15) between the cylindrical interior surfaces 61 of the contact-mating chambers. These walls are desirable to maximize pin-to-pin distance through air, for voltage-standoff purposes. To minimize material usage, we prefer to make the receptacle body 51 as shallow as practical. A countervailing consideration is maintenance of adequate wall thickness all the way around the contact-mating chambers 61. We prefer to address both these goals by forming nine very shallow vertical enlargements 66 of the body 51, only where needed just above and below the central regions of the contact-mating chambers 61. As shown in FIGS. 14 through 16, each enlargement 66 (or 66a through 66i) may take the form of a cylindrical segment. As seen in FIGS. 17 through 21, the wiring positions of the jack 70 are configured quite differently from those of the receptacle 50. As already noted, the forward end of the jack 70 is segmented to form nine discrete cylindrical contact chambers 74; these are separated by thin spaces 87 that accommodate the thin walls 77 in the receptacle 50. The cavities 75-76 in the jack 70 also are shaped quite differently from those of the receptacle 50. Except for the molding draft (shown exaggerated in FIG. 19), and an internal shoulder or contact anchor 81 about midway through, each cavity 75-76 of the jack 70 is nearly uniform in diameter. Each cavity 75-76 also is large enough to receive a female contact 110 (FIGS. 10, 11 and 23 through 29). In assembly, the contact is first precrimped onto an external wire 5 (or any of the wires 3, 5, 6, 7, 3' or 5' of FIGS. 1 and 2) and onto its insulation 8; and is then inserted from the rear end 86 of the jack 70 into the rear chamber 75 of the cavity 75-76. The contact 8 is advanced through the rear chamber 75 and partway through the annular internal shoulder 81. This motion continues until two forward stop-tangs 117 (FIGS. 23 through 27) formed in the contact 110 have passed entirely through the shoulder 81, and a rear stop 122/123 formed on the contact has engaged a rear stop surface 82 of the internal shoulder 81. The tangs 117 are biased outward from the contact body 121, as shown in FIG. 23. As they begin to pass through the shoulder 81, that shoulder bends the tangs temporarily inward against their internal bias and toward the contact body 121. When the rear ends 118 of the tangs pass through the shoulder 81, the tangs 117 spring back outward, positioning the tang rear ends 118 just forward of a front stop surface 83 of the shoulder 81. The annular internal shoulder 81 is then captured between the rear stop 122/123 and the tang ends 118 of the contact 110--or, to put it another way, the contact is anchored to the internal shoulder or "contact anchor" 81. As will be seen, the contact can be secured within the jack 71 by strain-relief features of our invention instead, or other methods if preferred. In either event, the female contact or socket 110 and its attached wire are firmly secured in the jack 70, and carried by the jack into engagement with a male pin in the receptacle 50, as previously described. The connector of FIGS. 12 through 21 is very readily adapted to ballast cans of a great variety of different shapes and larger dimensions, merely by making the ears laterally longer. This is shown in FIG. 22, where an extension segment 155 is formed so that the tips of the ears 55' are further outboard. In the configuration of FIG. 22, the engagement of the ears 55' (and the connector 50' generally) with the ballast notches 18/19 and end wall' 21 is substantially as described earlier for the previously discussed receptacle 50 of FIGS. 5, 6, and 8 through 16. Precisely the same jack 70 can be used with both receptacles 50' and 50. The contact 110 shown in FIGS. 23 through 29 is suited particularly for making and maintaining (in event of any vibration at the connections) a good wiping contact with the bared-lead (or bared-wire) male pins, without damage to the pins. It is similarly well-suited for repetitive connection and disconnection without damage. These benefits arise from provision of a circumferential, generally cylindrical contact body 111, 121 that generally encircles the pin and makes a very smooth engagement at a smoothly shaped constriction 112. Upon insertion--and thereafter in event of vibration--the constriction 112 effects a nondestructive cleaning action and a resulting excellent electrical connection. Each contact 110 is formed as one of a multiplicity of substantially identical units, initially held together in a row as by a common fabrication strip 140 (FIG. 23). Each contact 110 is removed from the fabrication strip 140 by breaking away along the score 141/135, after which the edge 135 (FIGS. 24 and 25) constitutes the rear end of the contact. After die-cutting, opposite sides of the blank for each contact are curled around to a top seam 125, and a segment 113 that is forward from the constriction 112 is flared outward to a bell 113. The tip 114 of the bell 113 is circular, except where interrupted at top and bottom by formed cross-slots 115. The cross-slots 115 enhance resiliency of the structure, and so enhance the wiping-contact action of the constriction 112. Initial die-cutting forms a "U"-shaped cutout 116 in each side wall, and thereby defines the previously mentioned tangs 117--which are slightly curled as shown in FIG. 26. Rearward from the cutout 116 and tangs 117 is a transitional segment 121 of the contact 110, followed by a rearward portion that is distorted to form three radial lobes 122, 123 (FIGS. 23 through 27). These two upper side lobes 122 and single bottom central lobe 123 cooperate to serve as the rear stop 122/123 mentioned earlier. The generally cylindrical forward segments 111, 121 appear in the phantom line in FIG. 27. Rearward of the stop 122/123 is another transitional segment 127, which angles upward toward the rear to elevate the next segment 128 closer to the centerline of the structure. That next segment 128 is configured for crimping tightly around the bare conductor, and accordingly the floor of this conductor-crimping segment 128 is elevated into alignment generally with the bottom of the frontal constriction 112. To enhance the longitudinal traction or grip of the conductor-crimp segment 128 against a bare wire, we prefer to preform serrations 132 (FIGS. 23, 24 and 28) around most of the interior surface of the crimp segment 128. Wrapping tabs 131 are formed to extend upward at both sides of the conductor-crimping segment. Behind another transitional segment (this one angled downward toward the rear) is an insulation-crimping segment 133, with longer wrapping tabs 136 to extend around the insulation of the wire. As FIGS. 25 and 29 show, the tips 134 of these tabs 136, and the tips 131 of the conductor-crimping segment as well, are all coined. It remains to describe the strain-relief features of our invention. The apparatus of FIGS. 30 and 31 provides strain relief simultaneously for all the wiring positions (not shown) of a receptacle or jack 50/70. Multiple punches 171a through 171i are mounted in a unitary chuck 172 that is driven downward vertically by a ram 173, held on a support 178. The workpiece, namely a half connector 50/70, is held by lateral spring-loading 175 in a jig 174 that includes a cradle 174', preferably inclined at a small angle--less than thirty degrees and preferably about fifteen degrees. If the cradle 174' is not angled, preferably the punches 171a through 171i are angled instead. In either case, their path through the connector body is off the perpendicular to the axis of the wire-holding chambers, by a small angle as noted above. It will be shown that such a relative angle enhances performance of our invention, but also that the invention can be practiced with the punches substantially at the perpendicular if preferred. Suitable pedestals and base 176 are included. These allow the entire apparatus and workpiece to rest on an ordinary workbench or like station 177. FIG. 32 offers a more-detailed but schematic view of a receptacle or jack 50/70, together with just one 171 of the relatively angled punches 171a through 171i ready for operation. The half connector 50/70 may be regarded as one outboard side of the receptacle 50 described earlier. An insulated lead 91 is shown extending into an insulated-lead holding chamber 63 in one wiring position of the receptacle 50. The body 51 of the receptacle is drawn broken away at 182, to show the bared conductor 96 extending onward within the body 51. The position 183 to be punched, in FIGS. 32 through 34, is substantially featureless. That is, the half-connector wall in that region is neither preperforated nor otherwise distorted or marked. It is also not prestressed. Thus in simplest theory no special preparation, external or internal, is required for practice of this aspect of the invention. The angled punch 171 is simply advanced, generally parallel to its axis, into the surface region 183 above the wire insulation 91. FIG. 33 shows that the punch preferably is formed with a tip that is angled slightly downward from the horizontal, allowing for the orientation of the punch shank 171. This tip first snaps away the material 183 at the forward edge of the impact area, and begins to bend the rearward edge--thereby starting to form a slug 183 of material. With continued advance of the punch 171 parallel to its axis, the rearward edge of the impact area also breaks away. The slug 183 is next bodily displaced into the chamber 63--and then further displaced into compressive wedged engagement with the insulation 91--leaving an aperture 184. The punch 171 is then withdrawn, leaving the assembly as FIG. 34 shows (with some exaggeration of the distortion 185 of the insulation 91). When a sharp tool 171 is used and the thickness of wall 51 is in a suitable range, the slug 183 snaps out cleanly enough that the wall retains much of its structural integrity. The slug 183, once pushed past the bottom edge of the now-perforated ceiling of the chamber 63, is cocked relative to the aperture 184--that is to say, no longer oriented for sliding motion in the aperture. No source of reorienting force is available, so the slug 183 remains cocked, and remains wedged between the inner cylindrical surface 63 and the insulation 91, at the aperture 184. By comparing FIGS. 33 and 34 it will be clear that the material 183 which forms the slug also assumes other positions: first a preliminary position, similar to that shown in FIG. 33 but without the initial fracture at the left end of the slug 183, or in other words the prefracture position of the material that is to become the slug; and an intermediate position very similar to that of FIG. 34, but resulting from the initial translation of the slug material 183 from its prefracture position to a position pressed by the punch 171 past the internal wall surface 63 and further into the insulation 91 than shown in FIG. 34, so that the upper left corner is within the internal cavity but not still within the hole 184. From consideration of the two positions just described, in relation to the two positions that are illustrated in FIGS. 33 and 34, it will be understood that the material 183 as shown in FIG. 34 is in a position that is significantly translated relative to a prefracture position, but not necessarily to the extent of the initial translation. Now light withdrawal force 186, up to twenty pounds or even somewhat more, may be applied to the insulated wire 91, in the form of tension on the wire outside the connector body 51. The wire responds by moving outward, carrying the slug 183 with it, but only far enough to jam the rear corner of the slug against the rearward edge of the aperture 183. The cocked slug 183 cannot escape either through the aperture 184 or--because the slug is jammed against the rearward edge of the aperture 184--longitudinally through the cylindrical chamber 63. Because the insulation 91 is also jammed against the slug 183, the slug locks the insulation in place and the wire cannot be withdrawn. As FIG. 35 shows, the end of the punch 171 can be made concave, yielding a double-cusped tip 171' to most effectively start breaking away the forward edge of the half-connector wall as a neatly formed slug. We have found, however, that this relatively elaborate tooling shape is not required. As already stated, no surface preparation or internal preparation is required in principle for our slug-lock strain relief. We have found, however, that one minor departure from this principle may be helpful. The half-connector general wall thickness is selected to optimize the structure as between structural strength and material cost. As may be expected, a different wall thickness is optimum for neatly snapping breakaway slugs into the insulated-wire chambers while otherwise maintaining the integrity of the walls. We have found that the slug-lock-optimizing thickness is smaller than the general-structure-optimizing thickness. For that reason we consider it advantageous to preform shallow recesses 181 (FIGS. 31 and 36) into the half-connector wall 51 at the points where the punches 171 will act. Each recess 181 may be formed with vertical walls 187, if desired. These shallow recesses, or mere slight reduction of the wall thickness in the general area where the punches will operate, are believed to be notably different from anything that could properly be called a preformation of the slugs themselves. Accordingly certain of the appended claims include the terminology "substantially without preforming of material to be displaced"; and we wish to make completely clear that this terminology encompasses structures in which simply shallow recesses are formed or the wall thickness is reduced, as shown. If provided with an angled tip, even a vertical punch 171' (FIG. 37) can create an angled slug 183' that deforms the insulation 91 and locks the insulation against the rearward corner of the aperture. Even a vertical punch with a right-angle tip can inset a slug 183" (FIG. 38) that deforms the insulation 91 enough to lock the wire against withdrawal. Yet another form of connector-body preparation appears in FIG. 39. Here a hole 186 is formed in the holding-chamber floor, directly opposite (below) the preformed recess 181' in the ceiling. The slug is then pushed downward somewhat more forcibly, squeezing the insulation at the bottom of the chamber downward and outward into the hole 186. Slight deformation is also thereby produced in the segment of the conductor, within the insulation, that is between the preformed hole 186 below and the punched aperture above. With sufficient force from the punch, the conductor deviates significantly out of line. Its deformation notably increases the combined resistance of the wire and insulation to withdrawal force. Our slug-lock principle is not limited to displacing a single slug of material over the center of a lead. Among many variations is that shown in FIGS. 40 and 41--where the insulation 91 is pinched slightly between two off-center slugs. FIG. 40 shows that the punch locations 181" (recessed as shown, if desired) are off to both sides of the insulated-wire chamber 63. FIG. 41 shows that the twin slugs 189 are driven vertically, along roughly punched-out channels 184", into positions that are partially within the chamber 63 and partially outside it laterally. FIG. 41 probably exaggerates considerably the regularity of the slugs 189, particularly at their sides that are remote from the wire 91/96: in the embodiment illustrated, those remote portions are formed largely by crushing of material originally adjacent to the chamber 63. FIG. 42 shows a different use of the slug lock, namely strain relief for a female contact 110 of the type previously described and discussed. Instead of engaging a conductor 8 or its insulation 5 as in previous illustrations, a slug 188 here moves into the space available above the conductor-crimping segment 128 of the contact 110. Upon application of withdrawal force, the intermediate section 121 of the contact promptly strikes the forward inside corner of the slug 188. This interference deters further withdrawal of the contact 110 and therefore of its attached insulated wire or lead 8, 5. As previously stated, one particularly beneficial characteristic of our invention is that its successful practice is relatively insensitive to precison of tolerances. To facilitate practice of the invention by those skilled in our field, however, we tabulate below representative dimensions and angles for one preferred embodiment. ______________________________________ mm inch______________________________________notches 18/19height 19 16.5 0.65width 18 2.7 0.11end wall 21width across folds 28 58.1 2.29(inside the tabs 27)aperture upper section 22height 9.7 0.38width 50.3 1.98aperture lower section 23height 3.3 0.13width 7.5 0.30receptacle 50overall width 58.2 2.29(across the ears 55)ear height 53 16.5 0.65ear thickness 54 2.5 0.10flange 52outside width (outside 50.0 1.95the side guides 61')inside width (outside 47.2 1.86the side guides 61')outside height 8.9 0.35inside height 6.1 0.24flange 52 depth (forward 1.5 0.06from hook cavity 57)antechamber 52 depth 5.3 0.21contact-mating chambers 61diameter 4.6 0.18full depth 8.9 0.35depth of rear-wall bulge 65 2.5 0.10width of flat annular seat 0.76 0.030surrounding bulge 65partitions 67 minimum width 0.38 0.015bared-lead guide channels 64diameter 1.07 0.042length (with rear c'sink) 3.3 0.13insulated-lead holding chambers 63diameter 2.16 0.085length (with rear c'sink) 5.1 0.20jack 70overall width (across the 46.7 1.84side rails 88)forward contact chambers 76/85outside diameter (taper) 4.45-4.57 0.175.0.180outside depth to 9.1 0.36stop surface 89width of space separating 5.59-6.35 0.220-0.250adjacent chambersinside diameter (taper) 3.35-3.45 0.132-0.136inside depth to 11.4 0.45contact anchor 81annular radius at tip 0.064 0.0025rearward contact chambers 75inside diameter (taper) 3.35-3.45 0.132-0.136depth to contact anchor 81 10.2 0.40(with inside beveland rear c'sink)hook 72/77height of heel 77 5.1 0.20length of shank 72 (from 10.7 0.42rear surface 86 tocapture surface 78)radius of extreme tip 206 0.3 0.01angle of shank 72 to contact- 3 degreeschamber centerline (withhook relaxed)angle of hook capture surface 85 degrees78 to shank 72angle of camming surface 73' 40 degreesto shank 72length of flat 204 between 0.8 0.03capture surface 78 andcamming surface 73'radius of transition 205 0.5 0.02between flat 204 andcapture surface 78anchor 81 inside diameter 2.69 0.106anchor 81 length (excluding 1.5 0.06rear bevel 82)anchor 81 rear bevel 82longitudinal length 0.5 0.020annular radial step 0.28 0.011radius of transition 0.5 0.02201 from bevel 82to inside diameterof anchor 81anchor 81 forward stop 83annular radial step 0.28 0.011angle of annular stop 5 degreessurface to diametercontact 110overall length 15.7 0.62material initial thickness 0.30 0.012longitudinal inset from bell tip 114 to:construction 112 1.8 0.07"U" cutout 116 4.1 0.16tip 118 of tang 117 7.4 0.29stop surface 122/123 9.4 0.37forward edge of conductor 11.4 0.45crimiping tabs 128/131rear edge of same 13.5 0.53forward edge of insulation 14.0 0.55crimping tabs 136/134bell 113 diameter 2.54 0.100constriction 112 inside diameter 0.89 0.035body 111/121 outside diameter 2.54 0.100elevation of conductor-crimping 1.14 0.045section 128 floor above body111/121 (and insulation-crimp-ing section 136 floor 133)height of conductor crimping-tab 2.03 0.080tips 131 above section 128floor (outside)height of insulator crimping-tab 3.3 0.13tips 134 above section 136floor 133 (outside)width of flat at coined tips of 0.10 0.004tabs 131 and 134angle of bevel at coined tips to 30 degreestab axisoverall width, across tang 3.81 0.150tips 118height of tank 117 cross-section, 0.76 0.030midway from root to tipradius of tang inside surface 126 1.27 0.050______________________________________ It will be understood that the foregoing disclosure is intended to be merely exemplary, and not to limit the scope of the invention--which is to be determined by reference to the appended claims.

4y

This is a continuation application of U.S. Ser. No. 09/025,071, filed Feb. 17, 1998. BACKGROUND OF THE INVENTION The present invention relates to document management to conduct an access control operation in which a document to be outputted as a retrieval result under a retrieval condition specified by a retriever and/or a document to be similarly displayed are/is restricted or controlled in accordance with an authorized of the retriever. In relation to these application fields, the present invention relates in particular to a document management method and a document management apparatus for supplying a large amount of document information of an electronic library system and the like to users via a wide area network such as Internet and Intranet. With recent rapid development and popularization of Internet, there can be seen a trend of supplying document information via a network to users. Particularly, in a large-sized document information system such as an electronic library system, there appears a need to provide a large volume of document information to users through a wide area network such as Internet and Intranet. In such a situation, World Wide Web (WWW) using a protocol called Hyper-Text Transfer Protocol (HTTP) capable of delivering document information to any place in the world is increasingly employed in document management systems for various uses thanks to development of high-performance retrieval functions. Furthermore, on the other hand, with increase in the amount of document information to be supplied to users, to provide a highly-developed service such as management of document information including secret information and management of charging operation, there is required an access control function in which a result of document retrieval and document to be displayed for a user are restricted in accordance with an authorized access level of the user. In the prior art, there has been adopted a method of implementing the access control operation in which when a user accesses a document management system, authentication of the user is carried out to conduct an access control operation for each database registered to the system. That is, when accessing a database in this method, the user inputs a user name and a password to the document management system. The system then achieves an operation to authenticate the user on the basis of the inputted user name and password. The system allows the user completely authenticated to access databases for which access authentication has been already established, thereby conducting the access control operation. However, in the method above of accomplishing the access control operation for each database through the user authentication, there arises the following problem. Namely, it is difficult to carry out an access control operation in a plurality of levels corresponding to groups to which users belong. This problem becomes remarkable especially when the system includes a large-sized document database. For example, in a case in which documents to be opened to users belonging to universities and public institutions are required to be discriminated from those to be opened to general users including private firms and companies, it is necessary to separately register these documents in the document management system. Namely, when users having different authorized access levels are allowed to access a document, the document is required to be registered to a plurality of databases. This accordingly increases the quantity of necessary resources such as magnetic disks and memories, which results in a problem of increase in the cost of the document management system. Additionally, processing steps such as data registration and backup steps become complex and hence there occurs a problem of conspicuous deterioration in the operation management and system maintenance. Furthermore, when an authorized access level is desired to be altered, document databases are required to be again registered to the system, which leads to a problem of a drawback in expandability. These problems related to the cost, operation management, maintenance, and expandability of the system appear as far more serious problems when the number of access control levels is increased, for example, in a case in which documents to be supplied to users are limited or restricted in accordance with a contract fee of each user in a document management system conducting management of charging operation. SUMMARY OF THE INVENTION In accordance with the present invention, there is provided a method of solving this problem in which for each document registered to the document management system, users allowed to access the document are registered as attribute information for each group to which the users belong. In this method, however, when a user conducts a retrieval operation in the document management system, it is necessary to refer to the attribute information for all documents retrieved as a result of the retrieval operation to determine whether or not the user belongs to a group of users allowed to access the document. Consequently, there arises a problem of elongation in the retrieval time. Moreover, in accordance with the present invention, there is specifically provided the following configuration. Thanks to the configuration, there can be implemented document management developing a remarkable advantage in the cost, operation management, maintenance, and expandability of the system for a large volume of document information of an electronic library system and the like in which the access control operation can be conducted in accordance with groups to which users belong. The present invention provides the following configuration. The configuration includes a text registration step of registering, at registration of a document, a registration document as text data; a data creation and registration step for data retrieval of creating retrieval data for the text data registered in the text registration step and registering the created data; and an access control table creation and registration step of assigning to the document completely registered through the text registration step and the data creation and registration step for data retrieval bit information corresponding to a user group beforehand registered and thereby creating and registering an access control table including information indicating whether or not a user belonging to the group is allowed to access the document. In addition, there is included an access control table created by assigning bit information corresponding to a beforehand registered user group to a registered document, the table including information indicating whether or not a user belonging to the group is allowed to access the document; a document retrieval step of retrieving, in a retrieval operation of a document, the document by referring to retrieval data beforehand registered; an accessible document list creation step of extracting from the access table document lists including entries thereof associated with a user group to which a retriever of the document belongs, conducting a conjunction operation between the document lists, thereby creating an accessible document list including a list of documents which can be accessed by the retriever; and an access control step of accomplishing a disjunction operation between a document retrieval result obtained through the document retrieval step and the accessible documents created through the accessible list creation step and thereby conducting document access control processing for the retriever in association with the document retrieval result. In this connection, the document retrieval step and the accessible document list creation step may be executed in an arbitrary order with respect to time. That is, these steps may be concurrently executed. In such a case, the steps may be overlapped with each other. Furthermore, it may also be possible to first execute any one thereof. Additionally, the document management method may include a user management table indicating a correspondence between each retriever and the user group assigned to the retriever and a step of conducting a retrieval operation through the user management table in response to a specification from a retriever and extracting user groups to which the retriever belongs. Moreover, there is provided a configuration which includes text registration means for registering, at registration of a document, a registration document as text data; data creating and registering means for data retrieval of creating retrieval data for the text data registered in the text registration step and registering the created data, and access control table creating and registering means for assigning to the document completely registered through the text registration step and the data creation and registration step for data retrieval bit information corresponding to a user group beforehand registered and thereby creating and registering an access control table including information indicating whether or not a user belonging to the group is allowed to access the document. Incidentally, the configuration may be implemented as a document information processing apparatus capable of retrieving document information in response to an input from a user. The apparatus includes an access control table created by assigning bit information corresponding to a beforehand registered user group to a registered document, the table including information indicating whether or not a user belonging to the group is allowed to access the document, document retrieving means for retrieving, in a retrieval operation of a document, the document by referring to retrieval data beforehand registered, accessible document list creating means for creating from the access table an accessible document list including lists of documents which can be accessed by the retriever, wherein documents which are obtained as a result of the retrieval by the document retrieving means and which are associated with the accessible document list are allowed to be accessed by the retriever. In other words, at least one of the document retrieving means, the accessible document list creating means, and the access control table may be disposed in a device other than the document information processing apparatus. Moreover, the configuration includes an access control table generated by assigning bit information corresponding to a beforehand registered user group to a registered document, the table including information indicating whether or not a user belonging to the group is allowed to access the document, document retrieving means for retrieving, in a retrieval operation of a document, the document by referring to retrieval data beforehand registered, accessible document list creating means for extracting from the access control table document lists including entries thereof associated with a user group to which a retriever of the document belongs, conducting a conjunction operation between the document lists, thereby creating an accessible document list including which is a list of documents which can be accessed by the retriever, and access control means for accomplishing a disjunction operation between a document retrieval result obtained through the document retrieval step and the accessible documents created through the accessible list creation step and thereby conducting document access control processing for the retriever in association with the document retrieval result. The configuration may further include a user management table indicating a correspondence between each retriever and the user group assigned to the retriever and means for conducting a retrieval operation through the user management table in response to a specification from a retriever and extracting user groups to which the retriever belongs. BRIEF DESCRIPTION OF THE DRAWINGS The objects and features of the present invention will become more apparent from the consideration of the following detailed description taken in conjunction with the accompanying drawings in which: FIG. 1 is a diagram showing the configuration of an embodiment of the present invention; FIG. 2 is a diagram showing an example of the group control table in an embodiment of the present invention; FIG. 3 is a diagram showing an example of the user management table in an embodiment of the present invention; FIG. 4 is a program analysis diagram showing an outline of document registration processing in an embodiment of the present invention; FIG. 5 is a program analysis diagram showing the contents of processing of the text registration program in an embodiment of the present invention; FIG. 6 is a program analysis diagram showing the contents of processing of the data creation and registration program for data retrieval in an embodiment of the present invention; FIG. 7 is a program analysis diagram showing the contents of processing of the access control table creation and registration program in an embodiment of the present invention; FIG. 8 is a diagram showing the access control table in an embodiment of the present invention; FIG. 9 is a program analysis diagram showing an outline of retrieval processing in an embodiment of the present invention; FIG. 10 is a program analysis diagram showing the contents of processing of the document retrieval program in an embodiment of the present invention; FIG. 11 is a program analysis diagram showing the contents of processing of the accessible document list creation program in an embodiment of the present invention; and FIG. 12 is a program analysis diagram showing the contents of processing of the access control program in an embodiment of the present invention. DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows an embodiment of the document management system of the present invention. The system shown in FIG. 1 includes the following constituent elements, namely, a display 10 to display thereon a retrieval result, a keyboard 20 to input therefrom commands for registration and retrieval operations, a central processing unit (CPU) 30 to execute registration processing and retrieval processing, a floppy disk driver 40 to read data from a floppy disk, a floppy disk 50 on which document data to be registered to a database is stored, a main memory 60 to temporarily store therein programs and data for the registration and retrieval operations, and a magnetic disk 70 to store therein various data items and programs and a bus 80 to connect these units to each other. In the main memory 60 , there are loaded from the magnetic disk 70 a system control program 100 , a registration control program 110 , a retrieval control program 120 , a text registration program 130 , a data creation and registration program for document retrieval 140 , an access control table creation and registration program 150 , a document retrieval program 160 , and an access control program 170 . Moreover, a work area 190 is reserved in the memory 60 . Additionally, on the magnetic disk 70 , there are reserved a text registration area 200 , a data registration area for data retrieval 210 , a registration area for various programs 230 , and a registration area for various tables 240 . Although the embodiment includes a magnetic disk, the present invention is not restricted by this embodiment. Namely, there may be used any device in which the areas above can be provided. In this regard, although these registration areas are reserved on the magnetic disk 70 in this embodiment, it may also possible to reserve these areas in another secondary storage such as a magneto-optical disk device. The configuration of the embodiment has been described. Next, description will be given of the processing flow of this embodiment. In the embodiment, when databases are created, the system control program 100 beforehand generates a group control table shown in FIG. 2 and a user control table shown in FIG. 3 and stores these tables in the table registration area 240 . In other words, to the group control table, identification numbers of groups for which an access control operation is conducted in the document management system and an outline of each of the groups are beforehand registered. Furthermore, stored in the user management table is information to identify groups to which each user belongs. That is, for each user registered to the system, ‘1’ is registered to a bit corresponding to a group to which the user belongs. In this connection, it may also be possible that a bit corresponding to a group to which the user belongs is set to ‘0’ and a bit corresponding to a group to which the user does not belong is set to ‘1’. Namely, it is only necessary to discriminate groups to which the user belongs from those to which the user does not belong. That is, the user management table of FIG. 3 indicates that a user, “Suzuki” belongs to groups 1 and 2 , and the group control table of FIG. 2 indicates that group 1 is a manager group of the document management system and group 2 is a group of in-house users in the organization of the system. Subsequently, description will be given of processing procedures of document registration and retrieval operations in the document management system of this embodiment. First, in response to a registration command inputted from the keyboard 20 , the system control program 100 initiates operation of the registration control program 110 to start document registration processing. Processing of the document retrieval operation will be described by referring to PAD shown in FIG. 4 . First, the program 110 activates the text registration program 130 in step 1000 . The program 130 registers text data of the registration document to the text registration area 200 on the magnetic disk 70 . The registration control program 110 then invokes the data creation and registration program for retrieval data 140 in step 1010 . The program 140 produces retrieval data in accordance with the text data stored in the area 200 and then registers the data to the area 210 on the disk 70 . Finally, the program 110 starts the access control creation and registration program 150 in step 1020 . The program 150 registers bit information for documents which can be accessed by users belonging to respective groups as shown in FIG. 8 to thereby create an access control table and then registers the table to the area 220 on the disk 70 and then terminates operation of the program 110 . An outline of processing of the registration has been described. Subsequently, description will be given of the contents of processing of the registration program by referring to a specific example. First, the text registration program 130 reads, in step 110 as shown in FIG. 5, text data of the registration document from the floppy disk 50 installed in the floppy disk drive 40 and loads the data in the work area 190 . Thereafter, the program 130 registers in step 1110 the data loaded in the work area 190 to the area 200 on the disk 70 to thereby terminate processing of the program 130 . In this connection, although this embodiment includes a floppy disk, there may be used any other storage media on which information can be stored. Moreover, in this embodiment, the registration document may be inputted not only from the floppy disk 50 but also from another apparatus, for example, by use of a communication line (not shown in FIG. 1) in the configuration of the embodiment. Next, the retrieval data creation and registration program 140 reads, in step 1200 as shown in FIG. 6, text data of the registration document stored in the area 200 of the disk 70 and loads the data in the work area 190 . The program 140 then creates in step 1210 retrieval data in the area 190 for the text data read in the area 190 . The retrieval data in this case is retrieval data for any one of various retrieval methods. For example, the data may be an index file to which words extracted from text data for index retrieval are registered or a learning file for a neurons-retrieval. Moreover, the data may conform to an n-gram method in which an index is created for partial character strings (n-gram) extracted from a text. When the retrieval data is completely created, the program 140 registers in step 1220 the retrieval data created in the work area 190 to the area 210 of the disk 70 to thereby terminate processing of the program 140 . Finally, the access control table creation and registration program 150 reads in step 1300 as shown in FIG. 7 the group control table shown in FIG. 2 and loads the table in the area 190 . Furthermore, the program 150 loads in step 1310 the access control table shown in FIG. 8 in the area 190 . The program 150 then executes in step 1320 processing of step 1330 for all registration documents. That is, in step 1330 , the program 150 refers to each entry of the group control table for each registration document and displays an outline of groups in step 1340 . The program 150 then determines in step 1350 whether or not the access is allowed for the pertinent group. When the access is to be allowed, the program 150 sets in step 1360 ‘1’ to the pertinent bit in the access control table, namely, there is recorded information that users belonging to the group are allowed to access the pertinent document. In other words, when the access right information is set to group 1 in association with a document with document number 7 , ‘1’ is set to an entry of group 1 corresponding to document number 7 ; whereas, ‘0’ is kept unchanged in entries of other groups. Incidentally, it may also be possible that ‘0’ is set to the pertinent bit and ‘1’ is set to the other bits. Only the pertinent bit is required to be discriminated from the other bits. When the processing above is completely finished for all registration documents, the program 150 deletes in step 1370 the group control table from the work area 190 . Finally, t he program 150 registers in step 1380 the access control table generated in the area 190 to the area 220 on the disk 70 to thereby terminates the registration processing. In this regard, it may also be possible to beforehand assign information identifying a group to a document to be registered such that in accordance with information assigned to a registration document to identify a group, the program 150 executes the access control determination processing. The contents of processing in the document registration have been described. Next, processing of the retrieval will be described. When a retrieval command is inputted by a user via a network to the document management system in accordance with the present invention, the system control program 100 initiates the retrieval control program 120 to start document retrieval processing. Processing of document retrieval will be described by referring to PAD shown in FIG. 9 . First, the program 120 invokes the document retrieval program 160 in step 2000 . The program 160 refers to retrieval data under a retrieval condition specified by the user, obtains as a result of retrieval a list of documents associated with the retrieval condition, and stores the list in the work area 190 . Next, the program 120 initiates the accessible document list creation program 170 in step 2010 to attain an accessible document list, i.e., a list of documents which can be accessed by the user, and then stores the list in the area 190 . Finally, the program 120 starts the access control program 180 in step 2020 . The program 180 accomplishes a disjunction operation between the list of retrieved documents created and stored in the area 190 by the document retrieval program and the accessible document list created and stored in the work area 190 by the program 170 to generate a list of retrieved documents after the access control determination, and returns the list to the user to thereby terminate the program 120 . An outline of processing of the retrieval has been described. Next, the contents of processing of the retrieval program will be described by referring to a concrete example in a case in which a retrieval operation is conducted by a user with user name “Suzuki”. First, the document retrieval program 160 analyzes a retrieval condition specified by the user in step 2100 as shown in FIG. 10 and refers to retrieval data in accordance with the retrieval condition to conduct document retrieval processing. The retrieval processing can be carried out in any kinds of retrieval methods such as an index retrieval, neuro-retrieval, and an n-gram retrieval methods. In addition, two or more kinds of retrieval methods may be employed in the document retrieval processing. Thereafter, the program 160 stores in step 2110 the list of documents obtained as a result of retrieval in the work area 190 and then terminates processing of the program 160 . Next, as shown in FIG. 11, the program 170 reads in step 2200 a user control table shown in FIG. 3 and stored in the area 240 on the disk 70 and loads the table in area 190 of the memory 60 . Thereafter, the program 170 accomplishes collation for a retriever name in a field of the user name of the user control table in the area 190 to extract a group number of a pertinent entry so as to obtain a group number associated with an access right of the retriever. Namely, in the case of this example, “Suzuki” is obtained through the collation from the entry of the user name in the user control table to attain groups 1 and 2 as the pertinent group numbers. Additionally, the program 170 refers in step 2220 to an entry in the access control table associated with the group number extracted in step 2210 to thereby obtain a list of documents which can be accessed by use of an access right of each group number. That is, in this example, the list of accessible documents is obtained by referring to entries of group numbers 1 and 2 in the access control table. Moreover, the program 170 executes in step 2230 a conjunction operation between the lists of documents extracted in step 2220 . Namely, in the case of “Suzuki”, the operation is conducted between a document list corresponding to group 1 and a document list associated with group 2 to thereby create an accessible document list which is a list of documents which can be accessed by the retriever. Thereafter, the program 170 stores in step 2240 the accessible document list to the area 190 . Thereafter, the program deletes in step 2250 the user control table from the area 190 and then terminates the accessible document list creation program. Finally, as shown in FIG. 12, the access control program 180 conducts a disjunction operation between the document list created in the area 190 in step 2300 as a result of retrieval by the document retrieval program 160 and the accessible document list created by the list creation program 170 to obtain a retrieval result of the access control processing. The program 180 then returns in step 2310 the retrieval result of the processing to the retrieval control program 130 . Finally, the program 180 deletes in step 2320 the retrieval result document list and the accessible document list from the area 190 to thereby terminate the access control processing. On receiving the retrieval result created through the access control processing, the retrieval control program 120 returns the retrieval result via the system control program 100 to the retriever and then terminates the retrieval processing. Description has been given of the contents of processing of document retrieval in the present embodiment. Although the access control table is established for each group in this embodiment, the table may be set for each user identifier information. This makes it possible to conduct the access control operation at a personal level. Additionally, in accordance with the present invention, the unit of access control operation is also applied not only to the referring operation to a document but also to an editing operation of a document. In this regard, the editing operation includes deletion, writing, addition, etc. of texts. As above, in accordance with the present embodiment, for each group to which users registered to the document management system belong, accessible documents are registered as an access control table at document registration. Under this condition, when a retriever desires to retrieve a document, information of accessible documents of a group to which the retriever belongs is extracted to accomplish the access control processing. Therefore, the access control operation can be achieved at a plurality of levels without dividing the database in accordance with the access control levels. In consequence, it is possible to provide a low-cost document management system having advantages in the operation management and maintenance thereof. Additionally, a new access control level (corresponding to a group number in the embodiment) can be achieved by registering a new entry to the access control table. Consequently, there is provided a document management system having improved expandability when compared with the conventional method in which a new database is to be additionally registered in the document management system. Incidentally, in the access control method in accordance with the present embodiment, the access control operation can be completed in the access right determination only by referring to entries (one megabit (Mbit)=125 kilobytes (kB) for one million document information items) of the access control table. In consequence, the retrieval response is rarely deteriorated for a large-sized document database. In accordance with the present invention, accessible documents of each group to which users registered to the document management system belong are registered as an access control table at document registration and hence the access control operation can be achieved at a plurality of levels without dividing the database in accordance with the access control levels. Moreover, there is provided a low-cost document management system having advantages in the system operation management and maintenance. Additionally, since a new access control level can be established by registering a new entry to the access control table, there can be provided a document management system having wider expandability when compared with the conventional method in which a new database is registered in the registration of a new entry. While the present invention has been described with reference to the particular illustrative embodiments, it is not to be restricted by those embodiments but only by the appended claims. It is to be appreciated that those skilled in the art can change or modify the embodiments without departing from the scope and spirit of the present invention.

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BACKGROUND OF THE INVENTION 1. Field of the Invention The invention relates to a combined cycle power plant with a gas turbine circuit and a steam turbine circuit, and more particularly, to a combined cycle power plant wherein the exhaust gases from a gas turbine transfer residual heat to a steam turbine via the working medium flowing in a once through steam generator. 2. Background of the Invention The water/steam circuit of current combined power plants is operated, without exception, on the basis of subcritical parameters. As a rule, the heat recovery steam generator for utilizing the waste heat from the gas turbines is designed with a drum boiler, with a once through boiler or with a combination thereof. In the case of large highly efficient plants, multiple pressure plants with reheating are sometimes used. However, in comparison with conventionally fired boilers, the flue gas temperature in the case of heat recovery steam generators is limited. In particular, the evaporation which occurs at a constant temperature leads to thermodynamic and technical design constraints. At the present time, heat recovery steam generators for utilizing the waste heat from gas turbine plants are designed, as a rule, with drum boilers. The steam circuit is cleaned by upgrading in the respective drum and by continuous or discontinuous blowdown of the drum. Upgrading occurs because the water evaporates in the boiler drum. Nonvolatile substances therefore remain in the boiler water and are increasingly upgraded. With the blowdown of the boiler water, the substances are consequently efficiently removed in concentrated form from the circuit. Moreover, in many instances, a solid alkalizing agent, such as trisodiumphosphate or sodium hydroxide, is added to the drum water in order to adjust the pH value in the boiler. However, if the heat recovery steam generators are provided with a simple once through boiler, this cleaning mechanism is not used, since such a boiler cannot be blown down. The cleaning of the water/steam circuit is carried out, in this case, in a condensate polishing plant, in which the condensate is filtered, before being introduced into the steam generator, and, if appropriate, is additionally desalinated by means of ion exchangers. However, in both types of boilers, one problem is that many undesirable substances, such as, chlorides and sulfates, are present in a volatile form, for example, HCl or H 2 SO 4 . This also applies to conventional circuit conditioning with ammonia in the form of volatile ammonium chlorides or of ammonium sulfates. Such materials may lead to corrosion and consequently to operating faults and damage. A heat recovery steam generator working with a drum boiler in a low-pressure system and with a once through boiler in the high-pressure system is known from EP-A1-0,359,735. In order to make the plant simpler and more efficient, however, in the disclosed plant the drum also performs the function of the feedwater tank/deaerator, such that the steam drum is provided with integrated deaeration. SUMMARY OF THE INVENTION Accordingly, one object of the present invention is to provide a novel plant which is restricted to the thermodynamically necessary elements of the water/steam cyclic process, thereby resulting in considerable cost reduction. The plant of the present invention is able to manage without a condensate polishing plant, without a feedwater tank/deaerator and without a steam drum. This is based, on the one hand, on the fact that metering with nonvolatile conditioning agents had strictly been dispensed with until now for once through boilers since these agents would be precipitated in the superheated boiler parts, and, on the other hand, on the knowledge that, where drum boilers are concerned, due to the addition of alkalizing agents the volatility of said chlorides and sulfates is drastically reduced so that these substances can easily be blown down, for example, in the case of phosphate conditioning of the boiler water. The advantages of the invention are to be seen, inter alia, in a considerable reduction of the plant and operating costs, in the reduction of risk due to the absence of a chemical plant in the water/steam circuit, and in an extreme simplification of the system, with the result that an improvement in reliability and availability may be expected. Thus, the present invention provides a heat recovery steam generator with a once through boiler having a separating bottle, wherein the impurities can be drawn off from the separating bottle (as when used for a drum boiler), if the separating bottle is operated under specific predetermined conditions. BRIEF DESCRIPTION OF THE DRAWING A more complete appreciation of the invention and many of the attendant advantages thereof will be readily obtained as the same becomes better understood by reference to the following detailed description when considered in connection with the accompanying drawing, FIG. 1, which illustrates diagrammatically an exemplary embodiment of the invention with reference to a combined cycle power plant. Only the elements essential for understanding the invention are shown, with the direction of flow of the working media being illustrated by arrows. DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now to FIG. 1, in the illustrated gas turbine system, fresh air which is drawn in via a line 1 is compressed to the working pressure in a compressor 2. The compressed air is heated in a combustion chamber 3 which is fired, for example, with natural gas, and the fuel gas thus obtained is expanded in a gas turbine 4 so as to perform work. The energy thus obtained is transferred to a generator 5 or the compressor 2. The still hot exhaust gas from the gas turbine 4 is supplied from the outlet of the gas turbine, via a line 6, to a heat recovery steam generator plant 7 and, after the heat is transferred, the exhaust gas is led from the latter into the open via a line 8 and a stack which is not illustrated. In the water/steam circuit, a multiple casing steam turbine 9, 10 is arranged on the same shaft as the gas turbine 4. The working steam expanded in the low-pressure turbine 10 condenses in a condenser 11. The condensate is conveyed from a hot well 12 by a pump 14, 20 directly into the steam generator 7. It is notable that the plant of the present invention is not equipped with either a condensate polishing plant or with a feedwater tank/deaerator which, as a rule, is steam heated. The heat recovery steam generator plant 7 is designed as a vertical boiler and, in the present case, works according to a dual pressure steam process. Of course, a horizontal boiler could also be used. The number of pressure stages could also, of course, be varied, as would be apparent to one skilled in the art. The low-pressure system is designed as a once through system. It includes, in the flue gas path of the boiler, a low-pressure economizer 15, into which the condensate is introduced via a feed pump 14, a low-pressure evaporator 16 and a low-pressure superheater 19. The superheated steam is carried over into a suitable stage of the medium pressure steam turbine 10 via a low-pressure steam line 28. The high-pressure system is also designed as a once through system and can therefore be designed both for subcritical and for supercritical parameters. It essentially includes, in the flue gas path of the boiler, the high-pressure economizer 21, the high-pressure evaporator 22 and the high-pressure superheater 23. The working medium is supplied to the high-pressure economizer 21 via a high-pressure feed pump 20. The superheated steam is carried over into the high-pressure part 9 of the steam turbine via a live steam line 24. For phase separation, a separating bottle 25 is provided in each of the two pressure systems, the outlet of the evaporators 16, 22 opening via a line 31 into said separating bottle, respectively. The separating bottles are connected, at their upper end, to the superheater 19, 23 via a line 32. At their lower end, the bottles are each provided with a return line 29 which opens into the hot well 12. At their lower end, each of the bottles is also provided with a blowdown line 30, through which the impurities are drawn off. The quantity of steam drawn off through line 30 is replaced by additional water which is introduced into the condenser at 35. The separating bottle 25 ensures that the superheater 19, 23 remains dry at all times and that superheated steam is available at the boiler outlet at an early stage. As soon as the pressure necessary for stable operation is reached in the high-pressure evaporator 22, the live steam can be used for starting up the steam turbine in a sliding pressure mode. According to one object of the present invention as described above, it is thus possible, in principle, to dispense with a condensate polishing plant. This is based on the realization that the impurities in the water/steam circuit can be drawn off in the region of the separating bottles 25 as further explained below. The water/steam circuit of the present invention can be cleaned both under full load and under part load. Under full load, the high-pressure system is overfed, that is, a larger quantity of water than is necessary is conveyed through the once through steam generator via the high-pressure feed pump 20. As should be apparent to one skilled in the art, if a single high-pressure feed pump is used, it must be designed to be correspondingly larger for the extra quantity of water. If the plant is provided with pump redundancy, for example in the form of 2×100% or 3×50%, the replacement pump may be employed to accomplish this overfeeding. The conveyed water quantity is adjusted in such a way so as to ensure that wet steam passes into the bottle 25. The impurities are bound in the water droplets of the water/steam mixture. In the bottle, the water fraction of the steam is separated by suitable means and is drawn off via the blowdown line 30. One advantage of this method is that the impurities are largely removed from the circuit even after only a few passes, that is, within a very short time. In a variant of the invention, in which circuit cleaning can be carried out by means of the feed pump dimensioned for normal operation, the steam generator is operated under part load, for example 80%. Accordingly, as in the full load method, the high-pressure system is overfed and the procedure is the same as in the method described above. The present invention also provides a further measure which reduces the volatility of the substances present and therefore makes it easier to separate them from the circuit. This is carried out by metering a conditioning agent and results in an advantageous reduction in the distribution coefficient. Since the above-described cleaning of the water/steam circuit via the separating bottle 25 requires the plant to operate in a special mode for a limited time, the metering of chemicals, i.e., conditioning agents, is also carried out only during this cleaning period, in which the separating bottle is operated under wet conditions. The chemicals are introduced into the feed line at 34, upstream of the feed pumps 14, 20, by suitable means. By virtue of this measure, the two pressure systems can be metered independently of one another as a function of their thermal states. The actual metering, that is the chemical to be used and its quantity, is carried out, in this case, as a function of the nature and degree of the impurity. Metering takes place continuously during the entire cleaning process. Ammonium metering (NH 3 ) and oxygen metering (O 2 gas) occurring for normal operation, which likewise takes place upstream of the feed pumps 14, 20 at 33, are adjusted by means of conditioning agents during cleaning. However, this is not an absolute condition, but depends on the nature of the impurity and therefore on the conditioning agent to be used. The general outcome is that, during normal operation, the separating bottle 25 is dry and there is no metering of chemicals in order to reduce the volatility of particular impurities. In contrast, wet steam has to pass into the bottle for cleaning under full load or under part load. According to the method described above, the necessary moisture passes into the bottle as a result of the overfeeding of the system, this being achieved by increasing the mass flow of feedwater and/or by running down the gas turbine. The reduction in volatility by means of chemicals, which is carried out during this cleaning operation, improves the degree of separation, which is particularly important with regard to the volatile substances. Moreover, this measure leads to a shortening of the cleaning operation. In the instance shown in FIG. 1, the inlet temperature into the boiler corresponds to the condensate temperature, since no steam-heated feedwater tank/deaerator is provided. Advantageously, the material for the so-called preheating surfaces of the once through steam generator is selected as a function of the gas turbine fuel and, in particular, its sulfur content and as a function of the condensate temperature, in order to prevent dew point corrosion. With a falling water-side inlet temperature, on the one hand, and/or with an increasing sulfur content, on the other hand, a transition can be made from simple carbon steel via low alloy steel to stainless steel. Of course, the invention is not restricted to the plant shown and described. The invention can be used irrespective of the type and design of the heat recovery steam generator and steam turbine plant, of the condensation system, of the presence of intermediate superheating, of the gas turbine plant and of the selected startup process. A horizontal boiler may be employed in contrast to the arrangement shown and described. Obviously, numerous modifications and variations of the present invention are possible in light of the above teachings. It is therefore to be understood that, within the scope of the appended claims, the invention may be practiced otherwise than as specifically described herein.

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CROSS-REFERENCE TO RELATED APPLICATIONS [0001] The present application is a continuation-in-part of U.S. patent application Ser. No. 10/795,803, field Mar. 8, 2004, entitled “Wheel Provided With Driving Means,” which is a continuation-in-part of U.S. patent application Ser. No. 10/619,926, filed Jul. 15, 2003, entitled “Wheel Provided With Driving Means,” which is a continuation-in-part of U.S. patent application Ser. No. 10/205, 405, filed Jul. 26, 2002, entitled “Wheel Provided With Driving Means,” which claimed foreign priority based on International Application No. PCT/NL01/00054, filed Jan. 26, 2001, which in turn claimed priority based on Dutch Patent Application No. NL 1014182, filed Jan. 26, 2000. Application Ser. No. 10/795,803, filed Mar. 8, 2004, entitled “Wheel Provided With Driving Means,” also claimed foreign priority based on Dutch Patent Application No. NL 1022873, filed Mar. 7, 2003 and Dutch Patent Application No. NL 1024565, filed Oct. 17, 2003. All of the above-referenced applications are hereby incorporated herein by reference in their entirety. FIELD OF THE INVENTION [0002] The invention relates to a wheel provided with electric driving means in the wheel as well as a method for co-ordinating the number of revolutions of at least two of such wheels attached to one vehicle. BACKGROUND OF THE INVENTION [0003] From the literature wheels provided with electric driving means in the wheel are known. In particular wheels are known that are provided with electro motors in the wheel. Examples of such wheels can for instance be found in DE-A-2719736, DE-A-4404889, FR-A-2561593, U.S. Pat. No. 4,585,085 and WO-A-95/16300. [0004] One of the problems occurring in the known wheels is the co-ordination between wheels when more than one driven wheel is used in one vehicle. [0005] Another problem occurring in the known wheels provided with driving means is that control means are necessary. Such control means are arranged outside the wheel in a vehicle. This renders the building of an electronically driven vehicle a complex megatronic venture. WO-A-95/16300 tries to solve this by arranging a part of the control electronics within the wheel. Using several such driven wheels in one vehicle is not possible however. [0006] It is an object of the invention to provide an electrically driven wheel of high efficiency. [0007] An additional object of the invention is to provide a wheel that is easy to mount. [0008] Additionally it is an object to develop a wheel that offers freedom of design of a vehicle. [0009] Another object is a wheel that is simple to replace and to demount. [0010] Another object is offering a wheel provided with driving means which in co-operation with other similar wheels can be deployed in one vehicle. [0011] Said problems are at least partially solved and at least a part of the ad-vantages is achieved by means of the wheel according to the invention. SUMMARY OF THE INVENTION [0012] The invention relates to a wheel provided with electric driving means in the wheel, the electric driving means comprising a rotor and a stator coaxially within the rotor and connectable to a vehicle, with an air gap provided between said rotor and said stator, wherein said wheel is provided with an air gap controlling bearing. [0013] Additionally the invention relates to a method for coordinating the number of revolutions of at least two wheel provided with electro motors in the wheels an further provided with control, measuring and operating means in the wheel for operating the electric driving means and with data communication means in the wheel, in which physically separated control systems control the amperage in each winding of the electro motors, the control systems in one wheel are operated by an operating system, a measuring system supplies information regarding the magnetic field strength to the control system and supplies the mutual position of the rotor and stator to the operating system, and the operating systems of the several wheels communicate one to the other by means of data communication means via a central processing unit. [0014] Because of the wheel according to the invention a driving concept has been realised that is efficient, simple to mount and can be integrated in a vehicle. [0015] Because of the method according to the invention it is possible to use several wheels provided with electric drive in one vehicle. [0016] Preferably the wheel comprises a rim which coaxially at the inner side is provided with a rotor provided with permanent magnets and which rotor and rim are connected to a central shaft, and a coaxial stator provided with windings which stator is situated between the central shaft and the rotor and being connectable to a vehicle. In that way the wheel is provided with an electro motor. As a result a simple drive of the wheel is possible. Moreover no transmission is needed, particularly no reducing transmission, in which great power losses have appeared to occur. [0017] More specifically the stator is divided into at least two groups of electrically and physically separated windings and each group comprises at least two windings each having its own control and measuring system, which control and measuring systems are situated in the wheel and the control and measuring systems are operated by an operating system which is also situated in the wheel. As a result a driving system is created that is integrated in a wheel, in which the driving system is very robust and not very sensitive to malfunctioning. [0018] The wheel according to the invention more preferably comprises means for exchanging data with the control, measuring and operating system of other, similar wheels. As a result it is possible to couple several wheels according to the invention to one vehicle, because of which a powerful propulsion of the vehicle can be realised. In order to make the data communication less sensitive to malfunctioning, the means for exchanging data to the outside preferably are optical communication means. [0019] In order to let either several wheels or one wheel according to the invention communicate with amongst others equipment outside of the wheel, the measuring, control and operating systems of a wheel communicate via a central processing unit outside the wheel. In this way for instance several wheels of one vehicle are able to communicate one to the other. [0020] In order to further reduce the sensitivity to malfunctioning of a wheel even more, the control system comprises means for controlling the strength of electric current through each winding separately. In this case a winding also means a coil. When a current runs through the coil or winding this results in a magnetic field. [0021] The control systems of the windings are connected to the operating system. Said operating system is hierarchically above the control systems and orders each control system to set and maintain a certain strength of electric current. [0022] The wheel according to the invention is also provided with measuring systems, in which the measuring systems comprise an encoder for measuring the number of revolutions and the angular position of the rotor with respect to the stator, and a current measuring device for measuring the current through each of the windings. As a result the current through each winding can be accurately set and calibrated. Additionally the operating system is able to operate the winding well, and set the phase on each winding for an optimal working of the electric drive. Additionally the measuring system is provided with means for measuring the mechanic torque, preferably by means of strain gauges that are able to measure the strain in material accurate to the nanometre. Such means for measuring strain or torsion, deformation in metal in general, as such are known to the expert. Comparison of mechanic resulting torque and accommodated motor power give an idea of the condition of the wheel. [0023] For a good working, the encoder preferably is connected to the operating system and the control systems are connected to the current measuring devices. As a result a modular system is created that is not very prone to malfunctioning. [0024] The operating system is connected to a central processing unit outside the wheel by means of the data communication means. As a result the co-ordination with other systems in a vehicle is possible. [0025] In order to cool the driving means in case of an all to great development of heat, the wheel is provided with cooling means, and of so desired also with active cooling means, such as fans. Additionally the wheel may be provided with means for water cooling. [0026] In order to render co-operation of several wheels according to the invention in one vehicle possible, the operating systems in the wheel preferably are provided with a “master” setting and a “slave” setting, in which by means of the communication means the central processing unit is able to have the operating system switch from the “master” setting to the “slave” setting and vice versa. For instance when taking bends either the power demand or the speed of several wheels will vary. In order to make co-ordination one to the other possible, the switch from the “master” setting to the “slave” setting and vice versa is influenced by either the power demand or the speed of the wheel. It is preferred here that the wheel demanding the lowest power, i.e. the wheel having the highest speed of revolution, has been set as “master”. [0027] In the method according to the invention it is preferred that the central processing unit has the operating system of the wheel demanding the lowest power function as “master”, and has the operating systems of the other wheel or other wheels, respectively, operate as so-called “slave”, in which each time the operating system of the wheel demanding the lowest power acts as “master” and the operating systems of the other wheels act as “slave”. As a result the driving system is easy to implement and control. [0028] In order to anticipate future situations during driving well, it is preferred that the central processing unit includes data of the wheel struts regarding the angular position when managing the operating systems of the wheels. [0029] The invention further relates to an assembly of at least two wheels according to the invention that are connected to a common central data processing unit by means of data communication means. [0030] The invention further relates to a vehicle wheel having an electro motor in it, in which the electro motor is a more than 8 pole, 3 or more phased, DC synchronous motor. [0031] Additionally the invention relates to a wheel provided with a housing mounted at a rotatable shaft, at the outside provided with a rim with tyre and at the inside provided with permanent magnets, and a housing mountable at a vehicle, rotatably connected to the shaft, provided with control, measuring and operating means and electric means for generating a magnetic field. Because of such a structure the wheel is simple to replace and can be mounted in a modular manner. Additionally a mechanic brake system is easy to mount on the shaft as an extra safety provision. [0032] Additionally the invention relates to a wheel provided with electric driving means in the wheel, means for measuring the mechanically delivered torque, means for measuring the torque by measuring the electrically accommodated power and means for comparing the mechanically delivered torque and the measuring to the electric power. As a result it has appeared possible to establish premature wear and malfunctions in the wheel, even before an actual defect occurs. By means of the communication means a (future) defect can be established even at a distance and possibly be remedied. [0033] Additionally the invention relates to a wheel provided with electric driving means in the wheel, provided with at least two galvanically separated motor windings, at least two galvanically separated power modules and at least two galvanically separated operating units for the power modules. [0034] The invention moreover relates to a wheel strut provided with vehicle attachment means for attaching the wheel strut to a vehicle, and wheel attachment means for attaching a wheel to the wheel strut, in which the wheel attachment means are rotatable about the longitudinal axis with respect to the vehicle attachment means and in which the wheel strut is provided with driving means for rotating the wheel attachment means with respect to the vehicle attachment means. [0035] As a result such a wheel strut is easy to mount on a vehicle, and the other means such a steering means for the vehicle and drive for wheels can easily be coupled. [0036] Preferably the vehicle attachment means and the wheel attachment means are spring-mounted to each other along the longitudinal axis by means of connection means. [0037] Preferably the connection means comprise a splined shaft which at one side is provided with a spline and on the other side is provided with driving means for rotating the splined shaft, and with a spline housing in which the splined shaft is situated and which spline housing at the bottom side is provided with accommodation means for a wheel shaft and attachment means for a wheel, and in which the vehicle attachment means are formed by a sleeve provided with means to connect the sleeve to a vehicle, in which the spline housing with splined shaft is at least partially accommodated in the sleeve, in which the spline housing and the sleeve are spring-mounted to each other by means of spring means, and the driving means are connected to the sleeve. [0038] The structure that can be realised in this way is simple, robust, and can be integrated well in and with existing vehicles and production methods. [0039] In order to attach a wheel the spline housing is provided with a receiving sleeve for a shaft which is positioned substantially perpendicular to the spline housing. As a result it is possible to attach a wheel stably and securely. [0040] Additionally the wheel strut comprises spring means for buffing the vertical movement of the wheel attachment means with respect to the vehicle attachment means. [0041] Preferably the wheel strut is provided with means for communicating with the driving means. [0042] Preferably the wheel strut is provided with means for communication with the operating means of a wheel according to the above-mentioned first aspect of the invention. Preferably the driving means of the wheel strut communicate with the operating means of a wheel according to the invention by means of the central processing unit. [0043] Said aspects of the invention can, if so desired, be combined. For instance a vehicle can be equipped with 2 or 4 wheel struts according to one aspect of the invention, and 4 or more wheels according to the invention. It is also possible for instance that a fork-lift truck is equipped with only one or two wheels according to the invention, but also with two wheel struts according to the invention. [0044] As a result of a high degree of automation the wheel strut and the wheel according to the invention are particularly suitable for use in fully automatically guided vehicles. Operation can also take place by means of a joystick and so-called drive-by-wire, in which the signals of for instance a joystick or steering wheel are converted into (electric or optic) steering signals. [0045] The invention additionally relates to a computer provided with software for the operation of one or several wheels as described, and/or for the operation of the wheel strut. Additionally the invention relates to a data carrier provided with such software. BRIEF DESCRIPTION OF THE DRAWINGS [0046] A number of specific embodiments of the invention will be elucidated on the basis of the figures. The figures serve to illustrate the invention. The invention, however, is not limited to the specific embodiments shown. [0047] FIG. 1 shows a wheel according to the invention. [0048] FIG. 2 shows the wheel of FIG. 1 in cross-section. [0049] FIG. 3 shows a cross-section of a wheel strut according to another aspect of the invention. [0050] FIG. 4 shows a diagram of a control and operating system of a wheel according to the invention. [0051] FIG. 5A shows a top view of a vehicle having wheels and wheel struts according to the invention. [0052] FIG. 5B shows a top view of the vehicle of FIG. 5A . [0053] FIG. 6 shows an alternative embodiment of the wheel according to the invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS [0054] FIG. 1 shows the wheel 1 according to the invention. In the figure the wheel is provided with a tyre 2 , which can be used in several embodiments. [0055] The tyre may for instance be a full rubber tyre for use in low speed vehicles such as tractors, fork lift trucks or other types of vehicles for cargo transport. The wheel diameter will preferably be approximately 800 mm. The tyre may also be designed as air pressure type for use in medium speed vehicles such as for instance city taxis and medium heavy cargo transport in urban areas. [0056] The tyre 2 is mounted on rim 3 , which is adapted to the various types of tires. A lid 4 has been mounted to the rim 3 , which connects the rim to the central shaft 5 . [0057] At the inside of the rim 3 the rotor 6 is attached on which at the inside the permanent magnets 7 have been glued. Said permanent magnets 5 rotate along with the rim 2 . The rim 3 with the tyre 2 , the rotor 6 with the permanent magnets on it and the other parts attached to the rim, the lid 4 and the central shaft 5 are the rotating parts of the wheel. [0058] Within the permanent magnets 7 an iron package 8 with windings 9 has been accommodated, with an air gap between the iron package 8 with the windings and the permanent magnets 7 . [0059] The iron package 8 with the windings 9 is mounted on the central carrier member 11 and mounted on cover plate 17 by means of clamping members 10 and 13 . Said cover plate 17 has been provided with a mounting flange (not shown, preferably a B5 flange of the 250 mm type) with which the wheel 1 is mounted to a vehicle. In the clamping member 13 which is provided with an accommodation space, the control electronics 20 , amongst others consisting of IGBT's for current control and programmable logical modules for the operating system, have been accommodated. The iron package 8 , the windings 9 , the clamping members, and the electronics are fixedly attached to a vehicle by means of said flange and therefore are not a rotating part. [0060] The central shaft 5 is provided with a hardmetal mounting bush 14 on which the bearings 23 of the wheel run. About the central shaft 5 the encoders 21 have also been mounted for measuring in what position the rotor 6 is situated with regard to the windings 9 . As a result the operating and control electronics 20 are able to control the exact phase of the voltage on each winding 9 at any moment, so that said phases are optimally adjusted to the position of the permanent magnets 7 with regard to each of the windings 9 . [0061] In the figure lid 4 is provided with blades 15 and 15 ′. One ring of the blades 15 has been mounted directly about the central shaft, a second ring of blades 15 ′ concentrically about the first ring of blades 15 . The blades 15 ′ are open towards the most general direction of rotation (clock-wise as seen from the vehicle side) of the wheel 1 . Said blades serve to guide air into the motor for cooling. The blades 15 about the central shaft with the air inlet openings are mounted opposite to the blades 15 ′. When driving the vehicle, to which the wheel 1 has been mounted, the blades 15 will guide air into the wheel 1 , and blades 15 ′ suck air out of the wheel. As a result an air flow to the inside will be created, which flows over a cooling body on the outer clamping member 10 . [0062] The blades function according to the principle of the centrifugal pump. The number of blades 15 about the central shaft is smaller than the number of blades 15 ′ in order to give the air expanded through heating more space and to be able to discharge it more easily. [0063] In addition to the passive cooling by means of the blades, fans for active cooling may be present in the wheel 1 . Said fans may for instance be activated when the internal temperature exceeds a certain value. [0064] The various internal parts of the wheel may, because of the nature of the structure according to the invention, be sealed off liquid proof in a simple manner. As a result it is possible that in addition to the passive cooling by means of blades and the active cooling by means of the fans, the inside of the wheel is cooled by means of liquid cooling. The cover plate 17 in any case seals off the operating and control electronics 20 from the outside world. [0065] The rotor 6 can be made of aluminium and of steel, depending on the speed and bearing power needed. [0066] The rotor 6 is carrier of the permanent magnets 7 , which ensure the torque transmission. They also ensure the guidance of the flux, which is necessary to have the magnets act as effectively as possible and thus creating a magnetic connection with the magnetic field which is generated in the stator. The stator is formed by the iron package 8 with windings 9 . [0067] Apart from the air cooling in the motor, heat can also be discharged by means of cooling ribs 24 . In the production stage they are integrated in a casting with the cover plate 17 . [0068] For the internal cooling of the electronics 20 a cooling body is provided. Said cooling body of course serves to cool the electronics but also has two additional functions, namely fixation of the stator and sealing off of the water cooling which can be used in larger power and higher voltages. In the figure the cooling body is still separated from the clamping member, but in series production this can become one structure part. [0069] Clamping member 10 together with the clamping member 13 of the electronics 20 ensures that the iron package 8 of the stator gets clamped and thus cannot possibly slide in axial direction with respect to the rotor 6 . As a result the magnets 7 remain exactly in their places with respect to the rotor 6 for optimal efficiency. [0070] The stator with windings 9 in FIG. 1 consists of 3 parts, but preferably the iron package of the stator will be made of one part. The windings 9 have been arranged around winding heads, which windings are wound according to a fixed pattern so that an optimal driving behaviour of the wheel 1 according to the invention is achieved. Electric currents run through the windings 9 , which currents generate the magnetic forces that are needed to let the rotor 6 rotate. The iron package 8 ensures an optimal guidance of the flux. A well-chosen iron package 8 guarantees a high efficiency of the wheel according to the invention. [0071] A sealing ring ensures the separation between the internal part of the air cooling and that part where the bearing of the wheel according to the invention and the electronics is housed. [0072] Furthermore a mounting bush 14 has been arranged as a support for the bearings 23 (e.g., 2 double-row angle contact bearings). Said mounting bush 14 has been designed in a high quality type of steel. The steel mounting bush 14 transfers the forces from the bearings on the central carrying member 11 and prevents the rolling out of the central carrying member 11 by the bearings 23 . Bearings 25 ensure the absorption of both the axial and radial forces and namely equally, so that during bends and irregularities in the road surface a stable rotation of the rotor 6 is obtained. Said stable rotation is very important because for an efficient working of the wheel according to the invention an air gap of approximately 2 mm at a maximum preferably is present between the rotor 6 and the stator. The bearings 25 function to ensure that said air gap remains in a working range (e.g., approximately 2 mm or less) during a large number of operation hours (10,000 hours at a minimum). [0073] Splines have been arranged between the stator and the central carrying member 11 so that said two members cannot possibly rotate with respect to each other. [0074] A retaining ring is pressed by the cover plate 17 and in this way locks the bearings, which in their turn fixate the stator with respect to the shaft. In this way it is guaranteed that rotor 6 and stator remain in the same position with respect to each other. [0075] A retaining sleeve keeps the hollow shaft encoder in its place and also ensures that the inner ring of the bearings is confined. The retaining sleeve in its turn is fixated on the central shaft 5 by a nut and screw thread. [0076] The central carrying member 11 supports the stator and is blocked against rotation there by means of 3 spline connections which are divided over the circumference in a regular pattern. In the carrying member 11 recesses have been arranged in the surface as a result of which during mounting openings are created through which cooling liquid can be transported. Said cooling may be necessary for higher voltages than 96V and larger capacities than 12 kW. [0077] The clamping member 13 has a number of functions. [0078] A: Together with clamping member 10 it clamps the central carrying member 11 and the iron package 8 , as a result of which the stator is entirely confined. [0079] B: It closes off the recesses that are meant to let the cooling liquid pass through. [0080] C: It forms an accommodation space or bowl in which the electronics are housed. [0081] Said accommodation space in its turn is closed off by the cover plate 17 . As a result the electronics 20 are completely sealed off from the outside air, which guarantees a failure free working of the wheel according to the invention. [0082] The ring bearing 25 ensures additional support of the rotor 6 , so that the air gap is guaranteed at all times. [0083] During mounting, the cover plate 17 ensures correct connection, sealing, and confinement of the entire structure. This is also the attachment plate for the mounting of the wheel according to the invention to a vehicle or a chassis and preferably is provided with a norm flange B5 of the 250 mm type, as a result of which the wheel can simply be fit in the existing concepts. By means of the cooling ribs 24 extra heat is discharged during driving. [0084] The permanent magnets 7 are manufactured in such a shape that they precisely fit into the rotor 6 . After gluing at the inside of the rim of the wheel the magnets form one unity together with the rotor. The magnets preferably are rare earth magnets. Preferably the permanent magnets have a magnetic field strength larger than approximately 1 Tesla. [0085] The encoder for hollow shaft 21 ensures that the way covered can be measured, and also drives the electronics 20 , so that a computer or central processing unit knows in which position the rotor 6 is situated with respect to the stator. This is of utmost importance for a shock free rotation of the rotor. [0086] The electronics and logic for operating the wheel, as well as the power electronics has been arranged within the wheel according to the invention. As a result it has become possible to achieve a number of advantages. [0087] One of the largest problems encountered at the moment by manufacturers of electronically driven vehicles, is that all sorts of components are spread over the vehicle that later on have to be connected to each other again. As a result the manufacturing of electronic vehicles is a time-consuming activity and therefore costly as well. Additionally the production often takes place in three consecutive stages as a result of which the production time is relatively long. [0088] FIG. 2 shows the wheel according to FIG. 1 in cross-section, as a result of which special aspects of the embodiment of a wheel according to the invention shown in FIG. 1 are further elucidated. The reference numbers here have the same meaning as in FIG. 1 . In the cross-section it can clearly be seen how the rim 2 , rotor 6 , permanent magnets 7 and the central shaft 5 are connected to each other by means of lid 4 . Furthermore it can clearly be seen how the windings 9 and the iron package 8 (the stator), and the clamping members 10 , 13 with the electronics 20 are connected to the cover plate 17 . In the cross-section it can clearly be seen as a result, how the electric driving means, in this case the electro motor, are situated in the wheel 1 . By placing an electro motor in such a way it has appeared possible to achieve very high efficiency, up to 50% higher than in the usual electrically driven vehicles. In particular an electro motor as described in the FIGS. 1 and 2 results in a great advantage. For instance, the motor having permanent magnets is capable of generating electricity itself when in neutral, because the motor acts as a dynamo. Because of the mounting of the motor in the wheel it is not necessary any more either to use a transmission or a differential. The number of revolutions of the motor need not be high either. [0089] FIG. 3 shows the wheel strut which is another aspect of the invention. The wheel stock 100 comprises a splined shaft 101 , at the one side provided with a spline 102 and at the other side provided with driving means 103 for rotating the splined shaft 101 . The driving means preferably consist of an electro motor 103 . The splined shaft 101 is rotatably situated in a spline housing 104 . At the bottom side said spline housing 104 is provided with accommodation means 105 for a wheel shaft 106 . The spline housing 104 is at least partially accommodated in a sleeve 107 provided with attachment means 108 for mounting the wheel strut 101 to a vehicle. The spline housing 104 and the sleeve 107 are spring-mounted to each other by means of a spring 109 . The housing of the electro motor 103 is connected to the sleeve 107 . The spline housing is provided with a shaft receiving sleeve 105 for a shaft which is positioned substantially perpendicular to the spline housing. The shaft receiving sleeve 105 is fixedly attached to the spline housing 104 . [0090] The spring 109 is meant to buff the movement of the part spline shaft-sleeve with respect to the part spline housing-shaft receiving sleeve. [0091] The sleeve 107 is provided with attachment means 108 for attaching the wheel strut 100 to a vehicle. The attachment means 108 are formed by a support 108 which is a permanent part of the structure and which is attached to the chassis or the structure with 2 conical pins and in that way forms one unity with the chassis or the structure of the vehicle. [0092] In order to protect the spring 109 from outside influences it is enveloped by a distance sleeve 112 which at its upper side is attached to sleeve 107 . Said distance sleeve 112 consists of two parts and is provided with small air outlet openings which buff the springy action of the suspension like a shock absorber. They also serve as end stop in case the vehicle is lifted with its wheels from the ground. The lower part of the distance sleeve 115 is slid into the upper part 113 . The distance sleeve members 115 and 113 are closed off one to the other with the help of a quadring 114 . [0093] In order to rotate a wheel electro motor 103 is activated. The rotation of the electro motor 103 is transmitted to splined shaft 101 . The rotation of the splined shaft is transmitted to spline housing 104 , as a result of which the wheel receiving sleeve attached to it rotates and a steering movement can be made. The electro motor can be provided with a transmission. The wheel strut is also provided with control and operating means for the electro motor. Additionally the wheel strut is provided with a so-called encoder which record the angular position of the wheel attachment means with respect to the vehicle attachment means. The wheel strut is also internally provided with data communication means, preferably optical data communication means. The encoder supplies operation information to the operating means of the wheel strut. The splined shaft 101 can also move up and down in the spline housing, as a result of which springing becomes possible. The vehicle attachment means can as a result move along the longitudinal axis with respect to the wheel attachment means. [0094] The spline housing 104 is the part of the wheel suspension that rotates and moves up and down. A wheel can be attached to the spline housing 104 by means of a B5 standard flange. A brake device can be also mounted to the rear side by means of the central shaft 12 / 106 . The central shaft 12 / 106 can also be equipped with a flange on which a wheel in neutral can be attached whereas on the other side disc brakes can be mounted. When the wheel according to the invention is mounted this part can be left out. [0095] The triangle support is a point of adhesion for a triangle. Said triangle is available on the market and makes it possible to increase the load of the spring leg from 1500 kg allowed load bearing capacity to 4000 kg allowed load bearing capacity. By using the triangle bending forces are no longer exerted on the suspension. [0096] An extended central shaft of a wheel according to the invention is necessary for the mounting of a wheel and may also serve to mount discs of a brake system. [0097] The spring ensures a comfortable road holding of the vehicle on which the wheel and the suspension have been mounted. In the 4 ton version with triangle the spring is indeed completely pressed in but ensures a minimal spring pressure of 1500 kg when the vehicle is positioned inclined and one of the wheels threatens to come off the ground. [0098] The rubber O-ring ensures the buffering of the spline housing 104 in the unlikely event of the load becoming so high that the spline housing 104 bumps against the support. [0000] Description of the Electronic Control for Operating the Synchronous Motor in the Wheel According to the Invention. [0099] The electronic control for the wheel according to the invention is built up modularly from several elements. The several elements are hierarchically adjusted to each other. The following elements can be distinguished. [0000] 1. Power Modules [0100] At the lowest step IGBT main current modules have been used. The structure present in said IGBT main current modules renders them highly reliable in themselves already and guarantees a low heat emission and an optimal efficiency. The main current modules control the current through the windings. The windings are divided into three groups, each having another phase. Per winding there are two main current modules. The main current modules are driven by a higher step, namely: [0000] 2. Current Regulators [0101] At the second step 2 IGBT main current modules are connected to a current regulator and driven by the current regulator. Together with a separate current sensor working according to the Hall principle (Hall sensor) they form an independent end step that controls the current in the accompanying motor winding. In this step the module and the current regulator are already galvanically separated from the operating electronics. A current regulator having two main current modules and Hall sensor are further called 4Q-modules. The main current modules with current regulator form a control system. There is a control system per winding. [0000] 3. Vector Generator [0102] The vector generator supplies an operating value to the so-called 4Q-modules (step 1 and 2), which thus generate a magnetic field vector by means of windings of the synchronous motor and thus determine the moment of torque. [0103] A so-called encoder or resolver, a measuring apparatus that very accurately measures the angle or the number of revolutions, makes the present position of the rotor with respect to the stator known to the vector generator. The quick calculation of the rotor position, which is derived from the sine/cosine signals of the resolver and the feedback value connected to it, ensures an optimal setting of the field vectors of the motor together with programmable logic modules, the so-called FPGA's. [0104] The entire function of the vector generator, due to the combination of a micro processor and the FPGA's, can be programmed entirely over an optical fibre cable. This means that new data or changes needed for a special use can immediately be implemented (by telephone or Internet) in the wheel according to the invention that is already in operation. Said changes do not only regard the software of the FPGA's, but also the hardware of the modules. It is for instance possible to change the relation in the motor itself when a winding or a module should fail so that the wheel can remain functioning. The vector generator forms the operating system. The encoder and the Hall sensors with the accompanying electronics in the described embodiment form the measuring system. [0000] 4. CPU or Central Processing Unit [0105] The first three stages are housed together in the wheel. The CPU is situated outside the wheel and communicates with the several wheels according to the invention that may be present on a car, by means of an optical ring data bus line (ORDABUL). It is also able to carry out calculations needed for the AGV's (automatic guided vehicles) regarding the road covered, odometrics when taking bends and diagnosing the complete driving concept. Each stage guards and reports the data important for the operational situation to the CPU. An error report is immediately reported to the stage above and this one immediately reacts by taking the necessary measures, before damage may arise. The stage above is able to activate an emergency program, which reacts to the error in the correct manner. As a result an error in one module hardly influences the entire vehicle. [0106] The modular system makes it possible to make a simple error diagnosis and to quickly locate the relevant components without having to subsequently perform complex adjusting or setting activities. [0107] An important difference with the usual control of Asynchronous/synchronous motors is the fact that in a preferred embodiment all motor windings are divided into three groups, each preferably consisting of 30 independent windings, electrically separated from each other and each winding being driven by its own 4Q-module. Here the 4Q-modules are merely connected to each other by means of the power supply voltage, as a result of which the following advantages arise: [0108] 1: Only two phases of the normal 3-phase drive are guarded and controlled. [0109] The currents in the third phase are calculated from the behaviour of the other two phases. This means a much greater freedom in operating the electronics, and for instance in buffering the failure of one or more modules. [0110] 2: The current distribution can be adjusted exactly so that each motor winding generates the same field strength. As a result the actual moments of torque in each winding, generated by the field, can be adjusted and are independent from the irregularities in the electric variables of the separate windings. [0111] 3: The magnetic tolerances of each winding can be calibrated separately by means of the vector generator. [0112] 4: When a 4Q-module fails or one of the windings has short circuited, the motor can still remain operational. A fuse or relay is able to separate the defect module or phase of the other 2 4Q-modules or phases without influencing them. In this way the motor is still able to brake or, when several wheels are used, to support them. The advantages of a stage-wise structure come to the fore here in particular. [0113] The functionality of the electronics described and their connection is further elucidated in FIG. 4 . By means of a block diagram the connection is schematically shown here and the hierarchy of wheels, wheel struts and other control and operating means in an electrically driven vehicle, such as for instance a remote or automatically controlled vehicle. A central processing unit or computer 200 controls the overall exchange of data between the several parts, and ensures the possible automatic control of the vehicle. The computer 200 is connected to energy management system 300 , namely the batteries, possible generators, fuel cells or solar panels, by means of data communication lines, for instance optical data communication lines. Additionally the computer 200 is connected to a display screen 400 on which the data are presented regarding the status of the various systems. The central computer 200 is also connected to various sensors that supply information regarding the vehicle position, possible obstacles, inside climate, and the like. The central computer moreover is connected to for instance two or more wheel struts 100 according to the invention. The numbers in the figure here correspond to the parts already described. [0114] The central computer 200 is moreover connected to at least one or more wheels 1 according to the invention. It can be seen that the wheel comprises three groups of windings 9 , 9 / 1 and 9 / 11 , control systems 32 , 32 / 1 and 32 / 11 for each group, and measuring systems 30 , 30 / 1 and 30 / 11 for each group. Additionally the wheel comprises the already described encoder 31 , which supplies data regarding the relative position of the rotor with respect of the stator to the operating system 33 superior to it. In the figure the three groups of the preferably in total at least 30 windings 9 , 9 / 1 and 9 / 11 in a wheel 1 according to the invention are shown. The windings 9 are preferably divided into three groups, each having another phase φ 1 , φ 2 and φ 3 . The current through each group of windings 9 , 9 / 1 and 9 / 11 is measured by a Hall sensor 30 . The value measured is passed on to the control system 32 . The control system 32 controls the current through a group of windings by means of 2 IGBT's. The control systems 32 are operated by an operating system 33 . Said operating system also receives data from an encoder 31 , which supplies angle information about the rotor with respect to the stator. As a result the operating system 33 is capable of choosing a good phase setting for an optimised working. The operating system 33 is coupled to a central processing unit 200 in a vehicle by means of data communication means 34 , preferably suitable for optical data communication. [0115] FIG. 5A shows a top view of a vehicle provided with four wheels 1 according to the invention. Said wheels 1 are each attached to a wheel strut 100 according to another aspect of the invention that has also been described. Said wheel struts are each provided with means in the wheel strut as a result of which each wheel is able to rotate and in which way it is possible to drive the vehicle. The vehicle is furthermore equipped with a central processing unit 200 and batteries and control systems 300 for them. In FIG. 5B a side view of the vehicle of FIG. 5A is shown. [0116] FIG. 6 shows an alternative embodiment of the wheel according to the invention. The reference numbers correspond as much as possible to those in FIGS. 1 and 2 . The vehicle side is shown with arrow A. The wheel according to FIG. 6 is provided with for instance water cooling. The inlet and outlet, respectively, of the cooling liquid is indicated by number 30 . The inlet and outlet 30 debouch in a space 31 around the shaft through which cooling liquid circulates. In this embodiment the measuring, control and operating means have been arranged in space 32 . The electronics are arranged with the print plates oriented towards a vehicle. The cooling liquid, preferably water, mainly serves to cool the windings. [0117] It will be clear that the above description was merely included to illustrate the working of an exemplary embodiment and not to limit the scope of protection of the present patent application. Variations and embodiments of the embodiments elucidated in the description above that are evident to an expert are also a part of the scope of protection of the present invention.

4y

BACKGROUND OF THE INVENTION 1. Field of Invention The present invention relates to the field of process management in a workflow environment on computer systems and the field of computerized transaction processing. More particularly, the invention relates to the implementation of computerized event-activities within workflow management systems (WFMS). 2. Definitions The following definitions of acronyms used throughout the specification may be useful in providing a better understanding of the subject matter of the present invention: 2PC: Two-Phase-Commit Protocol ACP: Atomic Commit Protocol DTS: Distributed Transaction Services ISO: International Standard Organization ODA: Object Definition Alliance OMG: Object Management Group OTS: Object Transaction Services TM: Transaction Manager TP: Transaction Processing WfMC: Workflow Management Coalition WFMS: Workflow Management System XID: Transaction Identification A transactional work item, or transaction in general, are not to be construed to be limited to a local or distributed transaction. Accordingly, a transaction may be of any of these types. Moreover, when referring generally to a transaction, the textual context will define if a general concept is meant or if a transactional work item as a specific embodiment of a transaction is denoted. 3. Description and Disadvantages of Prior Art A new area of technology, with increasing importance, is the domain of Workflow-Management-Systems (WFMS). WFMS supports the modeling and execution of business processes. Business processes control which piece of work of a network of pieces of work will be performed by whom and which resources are exploited for this work, i.e. a business process describes how an enterprise will achieve its business goals. The individual pieces of work might be distributed across a multitude of different computer systems connected by a network. The process of designing, developing and manufacturing a new product, and the process of changing or adapting an existing product, presents many challenges to product managers and engineers to bring the product to market for the least cost and within schedule while maintaining or even increasing product quality. Many companies are realizing that the conventional product design process is not satisfactory to meet these needs. They require early involvement of manufacturing engineering, cost engineering, logistic planning, procurement, manufacturing, service and support with the design effort. Furthermore, they require planning and control of product data through design, release and manufacturing. The correct and efficient execution of business processes within a company, e. g. development or production processes, is of enormous importance for a company and has significant influence on a company's overall success in the market place. Therefore, those processes have to be regarded similar to technology processes and have to be tested, optimized and monitored. The management of such processes is usually performed and supported by a computer-based process or workflow management system. Copies of the documentation for the following prior art is available through IBM branches: In D. J. Spoon: "Project Management Environment", IBM Technical Disclosure Bulletin, Vol. 32 , No. 9A, February 1990, pages 250 to 254, a process management environment is described including an operating environment, data elements, and application functions and processes. In R. T. Marshak: "IBM's FlowMark, Object-Oriented Workflow for Mission-Critical Applications", Workgroup Computing Report (USA), Vol. 17, No. 5, 1994, pages 3 to 13, the object character of IBM FlowMark as a client/server product built on a true object model that is targeted for mission-critical production process application development and deployment is described. In H. A. Inniss and J. H. Sheridan: "Workflow Management Based on an Object-Oriented Paradigm", IBM Technical Disclosure Bulletin, Vol. 37, No. 3, March 1994, page 185, other aspects of object-oriented modeling on customization and changes are described. In F. Leymann and D. Roller: "Business Process Management with FlowMark", Digest of papers, Cat. No. 94CH3414-0, Spring COMPCON 94, 1994, pages 230 to 234, the state-of-the-art computer process management tool IBM FlowMark is described. The meta model of IBM FlowMark is presented as well as the implementation of IBM FlowMark. The possibilities of IBM FlowMark for modeling of business processes as well as their execution are discussed. The product IBM FlowMark is available for different computer platforms. In F. Leymann: "A Meta Model to Support the Modeling and Execution of Processes", Proceedings of the 11th European Meeting on Cybernetics and System Research EMCR92, Vienna, Austria, April 21 to 24, 1992, World Scientific 1992, pages 287 to 294, a meta model for controlling business processes is presented and discussed in detail. The "IBM FlowMark for OS/2", document number GH 19-8215-01, IBM Corporation, 1994, represents a typical modern, sophisticated and powerful workflow management system. It supports the modeling of business processes as a network of activities; refer for instance to "Modeling Workflow", document number SH 19-8241, IBM Corporation, 1996. This network of activities, the process model, is constructed as a directed, acyclic, weighted, colored graph. The nodes of the graph represent the activities or workitems which are performed. The edges of the graph, the control connectors, describe the potential sequence of execution of the activities. Definition of the process graph is via the IBM FlowMark Definition Language (FDL) or the built-in graphical editor. The runtime component of the workflow manager interprets the process graph and distributes the execution of activities to the right person at the right place, e. g. by assigning tasks to a work list according to the respective person, wherein said work list is stored as digital data within said workflow or process management computer system. In F. Leymann and W. Altenhuber: "Managing Business Processes as an Information Resource", IBM Systems Journal, Vol. 32(2), 1994, the mathematical theory underlying the IBM FlowMark product is described. In D. Roller: "Verifikation von Workflows in IBM FlowMark", in J. Becker und G. Vossen (Hrsg.): "Geschaeftsprozessmodellierung und Workflows", International Thompson Publishing, 1995, the requirement and possibility of the verification of workflows is described. Furthermore the feature of graphical animation for verification of the process logic is presented as it is implemented within the IBM FlowMark product. For implementing a computer-based process management system, firstly the business processes have to be analyzed and, as the result of this analysis, a process model has to be constructed as a network of activities corresponding to the business process. In the IBM FlowMark product, the process models are not transformed into at executable form. At run time, an instance of the process is created from the process model, called a process instance. This process instance is then interpreted dynamically by the IBM FlowMark product. The concept of events as such, on the other hand, is known in the state of the art. Events, for example, play a role in database management systems. In database management systems, event/trigger mechanism have been developed for consistency checking in databases as described, for instance, in A. M. Kotz, Triggermechanismen in Datenbanksystemen, Springer Verlag, Berlin 1989. Also, events play a central role in the notion of active databases. In workflow systems, the semantics of an event is quite imprecise as applied by A. W. Scheer, Wirtschaftsinformatik, Springer Verlag, Berlin 1994, where the event can be a termination condition of a previous activity or an external signal, such as the arrival of a letter or, in general, an incident occurring independent from an activity informing an activity asynchroneously on some type of change. According to this prior art approach, an event is restricted to a quite limited spectrum of possible sources. The relationship between the activity and the event may be such that the activity requires that the event is signaled to it otherwise the activity will not continue beyond a certain point. It is also possible that an event signaled to an activity will be perceived by that activity and depending on that perception might modify the activity's ongoing processing. An event might result from anywhere within a computer system or even within networks of computer systems. Also, the source of an event might be a hardware device, some software construct, a human interacting with a running computer system and so forth. Whatever the precise merits, features and advantages of the above cited references, none of them achieves or fulfills the purposes of the present invention. Accordingly, it is an object of the present invention to tightly integrate event mechanisms into workflow management systems. This and other objects are achieved by the detailed description that follows. SUMMARY OF THE INVENTION Workflow management systems (WFMS), encompassing one or more computers, execute a multitude of process models consisting of a network of potentially distributed activities. Each activity information defines within the WFMS which available programs or processes execute that activity. The current invention teaches realization of an event as an event activity encompassed by said process model, said event activity being implemented as a special type of activity of said WFMS and said event activity managing an event which may occur internal or external to the WFMS. The present invention achieves a new level of integration between WFMS and event technology. By exploiting and reusing the activity features, very economic implementations for events are achieved. In addition, conceptual gaps between the concepts of activities, such as program or process and events, are completely avoided. Moreover, the approach enables handling of both, events occurring due to incidents within the WFMS, as well as events having their source external to a WFMS. By conceptually handling an event as any other activity, for instance as a process activity, this concept allows handling of any type of incident within a computer system as an event. The current approach thus supports the broadest possible spectrum of possible events. By reusing, to a certain extent, the implementations of activities, the overall system of a WFMS is not increased thereby supporting compact and very responsive overall WFMS. Event activities are implemented by inheriting features and capabilities of the class of activities or of a sub-class thereof according to the principles of object-orientation. Such an approach allows for an elegant and very simple way of reusing capabilities already available within a system. Event activities are implemented by associating with it an event generator being a program implementing said event. According to the invention an event activity may have associated with it an input container and/or an output-container, the event activity may be the source and/or target of one or more control-connectors and the event activity may be the source and/or target of one or more data-connectors. Moreover, it is taught by the present invention, that the event activity may be associated with a notification mechanism allowing to freely define one or more actions to be performed by the WFMS if the event activity is not completed within a freely defined time period. The present invention's approach to events supports a complete transparency whether an event is of internal or external nature. Nevertheless, the present invention implements the event generator as a special purpose program handling any type of event. Separating the general aspects of an event, like signaling a dedicated consumer that the event happened, from the event generator avoids that these functions have to be realized over and over again. Instead these general aspects are implemented only once within the WFMS and are handled by the WFMS automatically. Of course, all features which are available to normal activities are made available to event activities too, thus easing the implementation of events significantly. For instance, input and output containers provide an event generator with run-time information or make results of an event available to consumers of an event. The present invention introduces as one possible action, which may be performed by the notification mechanism, an automatic termination of the event if the event is not completed within a predefined time period. Such an approach provides simulation of a successful termination of an event activity if required. The present invention provides that an event activity may be the source of one or more outgoing control connectors targeted at corresponding target activities. Such a process model will then make sure that the target activities will be informed automatically by the WFMS on the event, once the event is signaled to the waiting event activity, that an event activity has been terminated. An outgoing control connector optionally may be associated with a logical predicate as an outgoing transition condition modeling the fact that a target activity will be activated if said event activity terminated and said outgoing transition condition evaluates to true. The current invention furthermore teaches that one or more incoming control connectors, of the corresponding source activities, may target at an event activity. Such a process model will then allow the WFMS to automatically start the event activity once a source activity terminated its processing. An incoming control connector optionally may be associated with a logical predicate as incoming transition condition modeling the fact that the event activity will be started only by the WFMS, if in addition, said incoming transition condition evaluates to true. The process graph provides definition via the control connectors which other activities are to be started after an event or which process activities automatically start an event activity. This technique establishes a standard approach to inform potential consumers on an event and to start an event activity and event generators. Thus the event activities, the event generators or the potential consumers are relieved from performing extra activities for that purpose. Moreover, event generators and event activities with interest in a certain event, either in creating or in waiting on an event, become significantly easier to implement. In addition, the above mentioned handling of the events are done automatically by the WFMS. The current invention does not restrict these source and target activities to a specific type of WFMS activities. Therefore, the source and/or target activities might represent standard process activities, program activities, or other types of activities, but according to the current invention it would be also possible that one or both of them represent event activities. In other words, the current invention also supports chains or even complex graphs of event activities. The WFMS is activating an event activity automatically when instantiating a process model if said event activity is not a target of a control connector. Thus no extra implementation is required to start a certain event generator. The WFMS takes care of these aspects automatically. The WFMS registers said event activity as awaiting consumer of said event once said event activity is activated by the WFMS and wherein further said WFMS registers said event as posted event once the occurrence of said event is signaled by said event generator. Due to this, the implementation of an event activity becomes much easier as the interest in a certain event is automatically detected by the WFMS by reading the process graph and the WFMS takes over responsibility to register an event activity's interest in that event. Moreover the implementation of event generators is also significantly simplified as an event signaled by an event generator is registered automatically by the WFMS as a posted event. This provides that a target activity is activated by said WFMS if, as a first condition the event activity terminated and if, as a second condition the outgoing transition condition evaluates to true independent at which point in time and in which sequence said first and said second condition are fulfilled. This behavior characteristic avoids that the signaled event is "consumed" if the transition condition is not fulfilled exactly at the point in time the event occurred. An WFMS navigator is extended by performing navigation of an operation through the process graph of a process-model by an event management system extending and inter-operating with said WFMS navigator. The event management system encompasses the component of an event monitor administering awaited events in at least one awaited event table and further administering signaled events in at least one posted event table. An event generator is signaling the occurrence of said event to said event monitor. This teaching extends the navigator with additional features to administer on one side all events which have been signaled to and to handle on the other side all potential consumers of an event and to associate both sides. Neither event generators nor activities have to take care of these aspects. The present invention provides for an event management system encompassing the component of an event manager maintaining information on the events allowing to verify correctness of an event if said event is being signaled. Such an access further increases the reliability of the overall system. The WFMS sends, if it detects that an event activity is awaiting for an event, an awaited event notification to said event monitor and if then said event monitor detects a matching posted event indication in said posted event table said event monitor indicates said event together with event data to said WFMS. If otherwise no matching posted event notification is detected, said event monitor stores an awaited event indication in said awaited event table. Also, the event generator indicates the occurrence of an event by a posted event indication to said event monitor which verifies said posted event indication by consulting said event manager and then stores said posted event indication in the posted event table and, if then said event monitor detects a matching awaiting event indication in said awaiting event table, it indicates this together with event data to the WFMS. This approach improves responsiveness of the WFMS by at once checking whenever either a new event arrived, or a new consumer is waiting, for an event whether a matching event-consumer pair can be detected allowing the WFMS to inform that consumer on the signaled event. Further additional advantages of the invention are accomplished by informing the event generator, if an awaited event indication is stored in said awaited event table, on this awaited event indication. This technique informs an event generator automatically on consumers awaiting some kind of event. Such an approach avoids that an event generator periodically has to check for possible event consumers and thus avoids performance degradations. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a diagram reflecting multiple aspects of the embedding of events as a new type of activity within a WFMS. FIG. 2 is a visualization of the two fundamental embedding modes of events as event activities within a process model. FIG. 3 reflects the major components of the Event Management System. FIG. 4 depicts the structure of the "awaited event table" and the "posted event table." FIG. 5 is a visualization of the FDL registration definitions required to model an event. FIG. 6 is a visualization of the FDL definition of an event. FIG. 7 is a visualization of the FDL definition for exploiting the notification mechanism for an event FIG. 8 is a simple sample process model reflecting the usage of event activities FIG. 9 reflects the most important data structures of the example of FIG. 8. FIG. 10 is a visualization of an event modeled as an event activity within the process model of the example of FIG. 8. DESCRIPTION OF THE PREFERRED EMBODIMENT The current invention is illustrated based on IBM's FlowMark workflow management system. Other WFMS could be substituted without departing from the scope of the present invention. Furthermore, the current teaching applies also to other types of systems which offer WFMS functionalities not as a separate WFMS but within some other type of system. INTRODUCTION The following is a short outline on the basic concepts of a workflow management system based on IBM's FlowMark WFMS: From an enterprise point of view, the management of business processes is becoming increasingly important: business processes or process for short, control which piece of work will be performed by whom and which resources are exploited for this work, i.e. a business process describes how an enterprise will achieve its business goals. A WFMS may support both, the modeling of business processes and their execution. Modeling of a business process as a syntactical unit in a way that is directly supported by a software system is extremely desirable. Moreover, the software system can also work as an interpreter basically getting as input such a model: the model, called a process model or workflow model, can then be instantiated and the individual sequence of work steps, depending on the context of the instantiation of the model, can be determined. Such a model of a business process can be perceived as a template for a class of similar processes performed within an enterprise; it is a schema describing all possible execution variants of a particular kind of business process. An instance of such a model and its interpretation represents an individual process, i.e. a concrete, context dependent execution of a variant prescribed by the model. A WFMS facilitates the management of business processes. It provides a means to describe models of business processes (build time) and it drives business processes based on an associated model (run time). The meta model of IBM's WFMS FlowMark, i.e. the syntactical elements provided for describing business process models, and the meaning and interpretation of these syntactical elements, is described next. A process model is a complete representation of a process, comprising a process diagram and the settings that define the logic behind the components of the diagram. Using various services provided by FlowMark the buildtime definitions process models are then converted into process templates for use by FlowMark at runtime. Important components of a FlowMark process model are: Processes Activities Blocks Control Flows Connectors Data Containers Data Structures Conditions Programs Staff Not all of these elements will be described below but are available as per the IBM FlowMark documents described heretofore. On this background a process, modeled by a process model within FlowMark, is a sequence of activities that must be completed to accomplish a task. The process is the top-level element of a FlowMark workflow model. In a FlowMark process, it can be defined: How work is to progress from one activity to the next Which persons are to perform activities and what programs they are to use Whether any other processes, called subprocesses, are nested in the process Of course multiple instances of a FlowMark process can run in parallel. Activities are the fundamental elements of the meta model. An activity represents a business action that is from a certain perspective a semantical entity of its own. With the model of the business process it might have a fine-structure that is then represented in turn via a model, or the details of it are not of interest at all from a business process modeling point of view. Refinement of activities via process models allows for both, modeling business processes bottom-up and top-down. Activities being a step within a process represents a piece of work that the assigned person can complete by starting a program or another process. In a process model, the following information is associated with each activity: What conditions must be met before the activity can start Whether the activity must be started manually by a user or can start automatically What condition indicates that the activity is complete Whether control can exit from the activity automatically or the activity must first be confirmed as complete by a user How much time is allowed for completion of the activity Who is responsible for completing the activity Which program or process is used to complete the activity What data is required as input to the activity and as output from it A FlowMark process model consists of the following types of activities: Program activity: Has a program assigned to perform it. The program is invoked when the activity is started. In a fully automated workflow, the program performs the activity without human intervention. Otherwise, the user must start the activity by selecting it from a runtime work list. Output from the program can be used in the exit condition for the program activity and for the transition conditions to other activities. Process activity: Has a sub-process assigned to perform it. The process is invoked when the activity is started. A process activity represents a way to reuse a set of activities that are common to different processes. Output from the process can be used in the exit condition for the process activity and for the transition conditions to other activities. The flow of control, i.e. the control flow through a running process, determines the sequence in which activities are executed. The FlowMark workflow manager navigates a path through the process that is determined by the evaluation to true of start conditions, exit conditions, and transition conditions. The results that are, in general, produced by the work represented by an activity is put into an output container, which is associated with each activity. Since an activity will, in general, require to access output containers of other activities, each activity is associated in addition with an input container too. At runtime, the actual values for the formal parameters building the input container of an activity represent the actual context of an instance of the activity. Each data container is defined by a data structure. A data structure is an ordered list of variables, called members, that have a name and a data type. Data connectors represent the transfer of data from output containers to input containers. When a data connector joins an output container with an input container, and the data structures of the two containers match exactly, the FlowMark workflow manager maps the data automatically. Connectors link activities in a process model. Using connectors, one defines the sequence of activities and the transmission of data between activities. Since activities might not be executed arbitrarily they are bound together via control connectors. A control connector might be perceived as a directed edge between two activities; the activity at the connector's end point cannot start before the activity at the start point of the connector has finished (successfully). Control connectors model thus the potential flow of control within a business process model. Default connectors specify where control should flow when the transition condition of no other control connector leaving an activity evaluates to true. Default connectors enable the workflow model to cope with exceptional events. Data connectors specify the flow of data in a workflow model. A data connector originates from an activity or a block, and has an activity or a block as its target. One can specify that output data is to go to one target or to multiple targets. A target can have more than one incoming data connector. Conditions are the means by which it is possible to specify the flow of control in a process. In FlowMark processes, models' logical expressions can be defined that are evaluated by FlowMark at runtime to determine when an activity may start, end, and pass control to the next activity. Start conditions are conditions that determine when an activity with incoming control connectors can start. The start condition may specify that all incoming control connectors must evaluate to true, or it may specify that at least one of them must evaluate to true. Whatever the start condition, all incoming connectors must be evaluated before the activity can start. If an activity has no incoming control connectors, it becomes ready when the process or block containing it starts. In addition, a Boolean expression called transition condition is associated with each control connector. Parameters from output containers of activities having already produced their results are followed as parameters referenced in transition conditions. When at runtime an activity terminates successfully all control connectors leaving this activity are determined and the truth value of the associated transition conditions is computed based on the actual values of their parameters. Only the end points of control connectors, the transition conditions of which evaluated to TRUE, are considered as activities that might be executed based on the actual context of the business process. Thus, transition conditions model the context dependent actual flow of control within a business process (i.e. an instance of a model). Business processes encompass long running activities in general; such an activity needs to be allowed to become interrupted. Thus, termination of an activity does not necessarily indicate that the associated task has been finished successfully. In order to allow the measurement of successfulness of the work performed by an activity, a Boolean expression called exit condition is associated with each activity. Exactly the activities the exit condition of which evaluated to true in the actual context are treated as successfully terminated. For determination of the actual control flow precisely the successfully terminated activities are considered. Thus the logical expression of an exit condition, if specified, must evaluate to true for control to pass from an activity or block. Besides describing the potential flow of control and data between activities, a business process model also encompasses the description of the flow of each activity itself between "resources" actually performing the pieces of work represented by each activity. A resource may be specified as a particular program, person, a role, or an organizational unit. At run time tasks are resolved into requests to particular persons to perform particular activities resulting in workitems for that person. Staff assignments are the means to distribute activities to the right people in the sequence prescribed by the control flow aspect of a business process model. Each activity in a process is assigned to one or more staff members defined in the FlowMark database. Whether an activity is started manually by the user or automatically by the FlowMark workflow manager, and whether it requires user interaction to complete or completes automatically, a staff member must be assigned to it. FlowMark staff definition entails more than identifying people at your enterprise to the FlowMark database. For each person defined, you can specify a level, an organization, and multiple roles. These attributes can be used at runtime to dynamically assign activities to people with suitable attributes. In the FlowMark workflow manager, program means a computer-based application program that supports the work to be done in an activity. Program activities reference executable programs using the logical names associated with the programs in FlowMark program registrations. The program registration can contain run-time parameters for the executable program. FlowMark consists, at the coarsest level, of a build time component and a run time component. The build time component supports the modeling of business processes according to the meta model described above and the run time component supports the corresponding semantics. Both components are implemented in a client/server structure. The client delivers the interaction with the user via an object-oriented graphical interface, invokes local tools, and provides animation. The server maintains the database for process instances, navigates through the process graph, and assigns the activities to the proper resources. Process definition includes modeling of activities, control connectors between the activities, input/output container, and data connectors. A process is represented as a directed acyclic graph with the activities as nodes and the control/data connectors as the edges of the graph. The graph is manipulated via a built-in, event-driven, CUA compliant graphic editor. The data containers are specified as named data structures. These data structures themselves are specified via the Data Structure Definition facility. FlowMark distinguishes three main types of activities: program activities, process activities, and blocks. Program activities are implemented through programs. The programs are registered via the Program Definition facility. Blocks contain the same constructs as processes, such as activities, control connectors etc. They are, however, not named and have their own exit condition. If the exit condition is not met, the block is started again. The block thus implements a Do Until construct. Process activities are implemented as processes. These subprocesses are defined separately as regular, named processes with all its usual properties. Process activities offer great flexibility for process definition. It not only allows to construct a process through permanent refinement of activities into program and process activities (top-down), but also to build a process out of a set of existing processes (bottom-up). In particular, process activities help to organize the modeling work if several process modelers are working together. It allows the team members to work independently on different activities. Program and process activities can be associated with a time limit. The time limit specifies how long the activity may take. If the time is exceeded, a designated person is notified. If this person does not react within another time limit, the process administrator is notified. It not only helps to recognize critical situations, but also to detect process deficiencies as all notifications are recorded in an audit trail. All data structures used as templates for the containers of activities and processes are defined via the Data Structure Definition Facility. Data Structures are names and are defined in terms of elementary data types, such as float, integer, or string and references to existing data structures. Managing data structures as separate entities has the advantage that all interfaces of activities and their implementations are managed consistently in one place (similar to header files in programming languages.) All programs which implement program activities are defined via the Program Registration Facility. Registered for each program is the name of the program, its location, and the invocation string. The invocation string consists of the program name and the command string passed to the program. Before process instances can be created, the process model must be translated to ensure the correctness and completeness of the process model. The translated version of the model is used as a template when a process instance is created. This allows to make changes to the process model without affecting executing process instances. A process instance is started either via the graphical interface, or via the callable process application programming interface. When a process is started, the start activities are located, the proper people are determined, and the activities are posted onto the work list of the selected people. If a user selects the activity, the activity is executed and removed from the work list of any other user to whom the activity has been posted. After an activity has been executed, its exit condition is evaluated. If not met, the activity is rescheduled for execution, otherwise all outgoing control connectors and the associated transition conditions are evaluated. A control connector is selected if the condition evaluates to TRUE. The target activities of the selected control connectors are then evaluated. If their start conditions are true, they are posted to the work list of selected people. A process is considered terminated if all end activities have completed. To make sure that all end activities finish, a death path analysis is performed. It removes all edges in the process graph which can never be reached due to failing transition conditions. All information about the current state of a process is stored in the database maintained by the server. This allows for forward recovery in the case of crashes. To achieve an integration of events within WFMS which is as seamless as possible, the basic approach of the current invention is to let events appear as a certain type of activity in terms of a WFMS. More precisely, this patent application teaches how events can be treated and implemented as a subclass of the class of activities inheriting (in the sense of object orientation) the common properties of activities. FlowMark activities are either program activities or process activities. Program activities are implemented via a program which is invoked when the activity is executed. Process activities are implemented via a sub-process which is started when the activity is executed. The sequence of execution of the various activities of a process model are described via the control connectors. Activities which are only the target of control connectors are called end activities. Activities which are only the source of control connectors, are called start activities. Which control connector is being followed is defined via predicates. Each activity is associated with an input container and an output container. The input container contains the data required by the implementation of the activity to perform the correct processing; the output container is filled by the activity with information to control the process and data to be used by subsequent activities. Data connectors are used to describe what data from which output container should be used for the data in the input container of activities subsequent according to the process graph. Activities are associated with a notification mechanism which allows to specify that an action, such as sending a notification message to a designated user, is performed if the activity has not been worked on for a defined period of time. The concept of events is the mechanism which allows the process modeler to specify that the process should wait at this point until the specified event happens. This event could be that a certain date occurs, or that a letter should be received from a customer. The occurrence of the event may be signaled from an activity within another process or from any other program, such as an agent in Lotus Notes. In general, an event is an incident occurring independent from an activity informing an activity asynchroneously on some type of change. This change might be internal or external to the WFMS. The relationship between the activity and the event may be such that the activity requires that the event is signaled to it otherwise the activity will not continue beyond a certain point. It is also possible that an event signaled to an activity will be perceived by that activity and depending on that perception might modify the activity's ongoing processing. An event might result from anywhere within a computer system or even within networks of computer systems. Also, the source of an event might be a hardware device, some software construct, a human interacting with a running computer system and so forth. The present invention shows how events can be modeled within a WFMS as a special kind of activity, the event activity. It specializes, in the sense of object orient technology, the general activity and inherits all properties of the general activity. Therefore, an event (activity) may be associated with an input and output container and may be the source and the target of control connectors as well as the source and target of data connectors; i.e. all constructs and techniques available to general activities are available to event activities according to the current teaching too. Events may have a start condition and may be associated with a notification. An event activity is associated with an event similar to process activities which are associated with programs. Thus, an "event" describes a conceptual and semantical entity, while the "event activity" is the model of that event modeled with the features of a WFMS. The programs associated with the event are called event generators and represent the means and constructs for creating or handling a particular event. FIG. 1 reflects multiple aspects of the embedding of events as a new type of activity within a WFMS according to the teaching of the current invention. The new type of activity, the event activity 100, is realized as a sub-class of the class of activities 101. Via relationship and inheritance mechanisms, the full spectrum of features and capabilities available to activities is made available to event activities too. Thus, event activities may exploit the available notification features 102, the full spectrum of data structure features 103, or the various connector features like control connectors 104 and data connectors 105. Also shown by FIG. 1 is the relationship of the model of an event 106 with one or more event activities 100 and the relationship of a program 107, an event generator implementing or handling an event, with one or more event activities 106. The control connectors originating from an event activity are treated as usual, i.e. their truth value of predicates potentially associated with those control connectors contribute to starting conditions of activities. Also, there may be more than one control connector emanating from a particular event activity. The usual navigation semantics will evaluate the transition conditions of the associated control connectors immediately; thus, events will not be physically consumed, in the sense that an event can be dedicated to a particular control connector leaving the event activity node, but are available for all originating branches. If exclusive validity of an event for a particular branch is required, it must be expressed via suitable transition conditions. An event activity can also be a target of a control connector. This means that an instance of the corresponding event is created, but not signaled, if the transition condition of the control connector pointing to the event activity is fulfilled. Using control connectors pointing to event activities can be used to explicitly activate events within particular process instance contexts. If an event is activated, the activity waiting for that event has registered for that event and all other activities being, according to the FlowMark process model, the target of a control connector originating at the event activity are then potential consumers of that event. FIG. 2 illustrates how two different cases for embedding events as event activities within a process model can be differentiated, exactly as is the case with regular activities. On the left side (1), the activity A 201 must have terminated successfully and the transition condition 202 between A and the event activity E 203 must have been evaluated to `true` before the event node E is sensitive for recognition. Thus, if an instance of E is signaled, this is not recognized before the transition condition between A and E is met. Once E is sensitive for recognition (i.e. activated) the activity B 204 has registered for the appropriate instance of E automatically through the modeled process graph. Event activities for this first type may be used, for instance, if the cause of an event is located at least partially within a process model itself. On the right side (2), the transition condition 210 between the event activity E 211 and the activity B 212 will be evaluated as soon as the event E is recognized even if the activity A 213 has not been terminated. Consequently, E is activated when the process model is instantiated, i.e. B has registered for E right away. When activating an event activity its associated input container is materialized. The usual rules for data connectors do apply. The output container of an event activity is created by the event generator associated with the subject event (see below). COMPONENTS OF EVENT MANAGEMENT SERVICES The navigator is the piece of the workflow management system that performs the navigation through the process graph. For handling events, this navigator is extended by an Event Management System encompassing event management services which are inter-operating with the navigator. These event management services are logically different components which may or may not coincide with physical means implementing those functions. FIG. 3 reflects the major components of the event management services. The event monitor 301 is responsible for keeping track of awaited and posted events. The event generators 302 are programs that signal the occurrence of an event to the event monitor. The event manager 303 keeps the information about events. When the navigator 304 detects that an event is expected by particular activities of a process instance this is indicated to the event monitor. If the event monitor finds a matching entry in its posted event table 305 it indicates so immediately to the navigator and passes the associated data with its response. Otherwise, the event monitor reflects the awaited event by an appropriate entry in the awaited event table 306. An event generator signals the occurrence of an event to the event monitor. The event monitor verifies the correctness of the event by consulting the event manager. If the event monitor detects a corresponding entry in the "awaited event table" this is indicated to the navigator. Otherwise, the event is inserted into the "posted event table". The tables "awaited event table" and "posted event table" are first of all logical objects. Physically they actually may be implemented as different or as common tables. TRACKING OF EVENTS It can be perceived that events, and their event indications within the posted and awaited event table, are managed in tabular formats as depicted in the FIG. 4. ProcID refers to the identifier of the process instance in which the event is waited for. The EventID identifies a particular event in this process instance (as node in the process model.) The EventName refers to the category of the event and the InputContainer column contains the actual values of the fields in the associated input container of the event. It has to be noted that the EventID is needed because events having an incoming control connectors are only "activated" if the transition conditions of the incoming control connectors are met and the start condition is true. An event which is not activated is not reflected in the "awaited event table". Events with no incoming control connectors are activated at process instantiation time. The posted events table is used to store generated events which are currently not waited for, as no potential consumer has registered for it. Such an event is kept in this table until somebody registers for it (potentially, an event may be kept "forever") or, if it is removed, via garbage collection. The ProcID column in this table represents an optional value for tupels of this table and can be used for specifying particular process instances which might consume the event instance. CANCELLING EVENTS An awaited event can be cancelled in two ways: (1) as the result of a notification action, such as FORCE TERMINATE, or (2) through an explicit request from the user via functions supplied by the event monitor. When an awaited event is cancelled, it is removed from the waited event table and the event monitor signals the completion of the event to the navigator. Any outgoing control connector is treated as if the event had happened normally. EVENT IDENTIFICATION The association of an incoming event, such as receiving a letter, with the waited for event is performed by comparing the identification fields provided by the event generator with the fields defined in the input container plus the fields defined in the input container by default, which is the process instance identification and the event identification. No problem arises if the event generator itself provides the process instance identification and the event identification. If the process instance identifier is not supplied, the fields in the input container are compared with the appropriate fields delivered by the event generator (signature matching). EVENT GENERATOR The event generator signals that an event has happened by calling the event monitor via the event monitor interface. The event generator can determine when the event should be signaled. This can be done by periodically querying the event monitor to determine if a new entry for the event generator has been entered in the awaited event table. An event generator may also register itself with the event monitor and request that each new registration of an awaited event is signaled to the event generator. The supplied date/time event generator, for example, has a data structure with a date field and a time field. These fields can either be filled by a data connector leading to that event or values set as defaults by the process modeler. The time/date event generator has registered with the event monitor that it should be called when a new event is registered. EVENT MONITOR PROGRAMMING INTERFACE The event monitor provides an application programming interface to allow applications to request event monitor functions. The set of functions include requests, such as querying the posted event table, removing entries from the posted event table, querying the awaited event table, removing entries from the awaited event table, and inserting entries into the posted event table. EVENT REGISTRATION An event activity is always associated with an event. The event has a number of properties: the name of the program implementing the event generator, the name of the event, and an indicator whether the event generator should be started as part of starting the FlowMark server. An important property is the operation mode of the event generator, which defines whether the event generator should be called every time a new event is added to the awaited events table or not. If specified, this allows the event generator to keep internal tables for efficient processing and does not require periodically reading the awaited event table. EVENT NOTIFICATION Events also inherit (in the sense of object oriented technology) the notion of notification from the activity. Notification allows to define actions which are taken whenever the defined time for completion is exceeded. Extensions to the notification mechanism allow to specify other actions than just sending a notification message to a designated person. These extensions include actions like terminating the activity. PROCESS MODEL ADDITIONS The support of events requires minor additions to the FlowMark Definition Language (FDL). Events are registered (in the sense of the FDL) via the EVENT section. It is similar to the PROGRAM section which supports the registration of programs. FIG. 5 shows the FDL registration of the event "Wait for Customer Response". The associated generator program is "MailCheckProgram". The program is started as a result of starting the FlowMark server, specified due to AUTOSTART, and is notified whenever an event is entered into the awaited event table, specified due to NOTIFY. Event activities of a process model are defined via the EVENT -- ACTIVITY section. This mechanism is almost identical to the PROGRAM -- ACTIVITY keyword. The event type is specified via the EVENT -- TYPE keyword followed by a string containing the event type. A particular event type may be specified only once within a process model. FIG. 6 shows how an event is defined. The data structure "Event Identification" defines the structure of the input container associated with the event. It contains all relevant information to identify the event. This information is used by the event monitor to compare it with the information supplied by the event generator. The data structure "Response Information" defines the structure of the output container associated with the event. The data is supplied by the event generator. Notification of events is enhanced to provide the capability to force terminate the event, that means that the event is considered complete even if no event has been signaled during the specified time. FIG. 7 shows how it could be specified that it should only be waited 14 days for the customer letter to arrive. ADVANTAGES The proposed method of treating events as activities has, besides the effect of offering a seamless extension and transition of workflow activities, a number of advantages over other possible approaches that treat events differently. 1 Events follow the same metaphor as activities. 1.1 Control Connectors activate an event. The predicates on the incoming control connectors, as well as, the outgoing control connectors allow to specify which event should be waited for and which activity should be executed as the result of the happening of an event. Events without an incoming control connector are immediately activated as are start activities. 1.2 Data Connectors allow to fill the input container with the event relevant data. No new mechanism is required to identify the instance of the event for which it should be waited for. 1.3 Input Containers identify to activities what the context is in which they are called. The same is true for event activities as the contents of the input container identifies the particular characteristics of the event which is waited for. 1.4 Output Containers contains the process relevant information generated by an activity. For event activities, the event signaler provides this information, for example, the identification of the letter which has been received, which is process relevant information. 1.5 Notification allows to specify what should happen if an activity has not been completed within a defined time limit. The same behavior is true for event activities, where this mechanism is used in the same way. 1.6 Events can be handled within Spheres of Joint Compensation the same way as activities. 2 Events can be graphically managed the same way as are activities. 3 Events can be described in the FlowMark Definition Language with similar constructs as program activities. 4 Treating events as activities allows to re-use the code used for processing process models, such as navigating the graph. Re-use of this code provides a number of advantages, such as 4.1 Less errors 4.2 Easier testing 5 Events can be monitored the same way as other activities via the process instance monitor. In summary, these advantages help to compress the overall system, contribute to minimize the implementation effort and thus, increase the responsiveness of the WFMS. EXAMPLE 1 A simple process model in FIG. 8 illustrates the usage of events. In a claims processing application of this example, additional information is required from a customer 801. The process waits until information is received 802. If the customer responded via fax, the fax is processed with a certain piece of software 803, otherwise another piece of software is used 804. FIG. 9 shows the definitions of the most important data structures being of importance within the example of FIG. 8. Finally, FIG. 10 is a visualization of the event modeled as an event activity "Wait for Response" in lines 5 to 9 within the process model of the example of FIG. 8. FIG. 10 further demonstrates in lines 14 to 21 usage of control connectors and in line 21 to 31 usage of data connectors for the event activity. CONCLUSION A system and method has been shown in the above embodiments for the effective implementation of events as activities in process models of workflow management systems. While various preferred embodiments have been shown and described, it will be understood that there is no intent to limit the invention by such disclosure, but rather, it is intended to cover all modifications and alternate constructions falling within the spirit and scope of the invention as defined in the appended claims.

4y

BACKGROUND The present invention relates to lifting devices and more particularly to hand operable lifting jacks of the telescoping tube type. Examples of jacks of this type are disclosed in U.S. Pat. Nos. 2,565,401 (issued Aug. 21, 1951) and 3,738,613 (issued June 12, 1973). Lifting jacks are frequently provided with covers to protect the drive mechanism from the environment. Usually, the covers require tools for removal. Furthermore, the drive mechanisms are often expensive to manufacture and difficult to service. The primary object of the present invention is to provide an inexpensive manually operable lifting jack which is easy to service. Another object of the present invention is to provide a lifting jack having an easily removable cover for the drive mechanism. SUMMARY The present invention provides a lifting jack for raising loads such as trailers and agricultural equipment. The lifting jack has a first tubular frame member, a second tubular frame member movably interconnected with the first frame member, and a selectively operable drive mechanism for moving the second frame member relative to first frame member. The drive mechanism includes a bracket fastened to the second frame member. The bracket has two apertures for pivotally mounting a shaft. A protective cover is removably fastened to shaft to protect the drive mechanism from the environment and to improve the ornamental appearance of the jack. In the preferred embodiment, the cover is formed of a resilient material and has one or two walls located near portions of the shaft. Each of the walls has a slot that is open at one of its ends and has an enlarged aperture at the other of its ends. The cap is removably snapped onto the shaft by inserting a portion of the shaft into the slot and forcing the cover against the shaft until the cover elastically deflects to permit the shaft to be seated in the enlarged aperture. The many features, objects and advantages of the present invention will become apparent to those skilled in the art when the following detailed description of the preferred embodiment is read together with the attached drawings. BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is a front elevational view of the implement jack of the present invention; FIG. 2 is a side elevational view thereof; FIG. 3 is a sectional view taken along line 3--3 of FIG. 1; FIG. 4 is a sectional view taken along line 4--4 of FIG. 1; FIG. 5 is an enlarged partial front elevational view similar to FIG. 1 but with parts of the implement jack cutaway; FIG. 6 is a view similar to FIG. 5 but illustrating an implement jack with a modified cover; FIG. 7 is a perspective view of the cover of FIG. 6; FIG. 8 is a bottom view thereof; and FIG. 9 is a sectional view taken along line 9--9 of FIG. 5; DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now to the drawing and more particularly to FIGS. 1 and 2 thereof, there is illustrated a lifting jack 10 constructed in accordance with the present invention. The lifting jack 10 has a rectangular base 12 having a flat portion 14 designed to rest horizontally upon the ground when the jack is in use. The base 12 also has four upturned edges 16a-d. As is well known in the art, a first tubular frame member 18 is attached, for example by welds (not illustrated), at its lower end 20 to the center of the flat portion 14 of the base 12. The upper portion of the first tubular frame member 116 is telescopically inserted into a second circular frame member 22, as illustrated in FIGS. 3 and 5. The second frame member may be reciprocated relative to the first frame member along their common longitudinal axis. A lifting mechanism 24, best illustrated in FIGS. 3-5, is provided to permit the user of the lifting jack 10 to selectively raise or lower the second frame member 22 relative to the first frame member 18. The lifting mechanism 24 shown in the drawing includes a disk-shaped plate 26 secured by welds 28a and 28b (FIG. 5) to the uppermost end of the second tubular frame member 22. A U-shaped bracket 30 (FIG. 5) is provided having a flat central portion 32 welded or otherwise fastened to the top surface 34 of the plate 26. Alternatively (not shown) the plate 26 may be omitted and the bracket 30 may be welded directly to the second tubular frame member 22. The bracket 30 has upwardly extending arm portions 36a and 36b on either side of the central portion 32 of the bracket. A pair of aligned apertures 38a and 38b are provided through a pair of bosses 40a and 40b of the arm portions 36a and 36b, respectively. Bushings 42a and 42b having shoulders 44a and 44b are pressed into the apertures 38a and 38b, respectively. Since the bushing 42a experiences less of a load than the bushing 42b, as will be apparent to one skilled in the art, the bushing 42a may in some cases be omitted. A crank 48 is provided having at one of its ends a shaft portion 50 journaled in the bushings 44a and 44b. A pair of C-clips 46a and 46b are inserted into appropriate annular channels (not illustrated) to secure the shaft 50 and the bushings 42a and 42b to the bracket 30. The crank 48 is formed from a single length of tubing or round stock, as shown in FIG. 1. The crank 48 has the shaft portion 50, a ninety degree (90°) bend (shown at 52), an arm portion 54, a second ninety (90°) degree bend (shown at 56) and, at its end furthest from the shaft portion 50, a handle portion 57. A handle 58 is interconnected with the handle portion 57 of the crank 48. A cover 60, shown in elevation in FIGS. 1 and 2, is fitted over the bracket 30 and the shaft 50 to partly enclose the lifting mechanism 24. As shown in the sectional views of FIGS. 3 and 4, the cover 60 is a hollow element formed of a resilient material. The specific aesthetic details of the exterior surface of the cover 60 are not important to the present invention, such details being principally of ornamental significance. The cover illustrated in FIGS. 3 through 5 has an inner compartment 62 defining an enclosure for the upper portion of the lifting mechanism 24. The cover has an arcuate top wall 64 (FIGS. 3 and 5) that blends into each of two flat side walls 66a and 66b, as shown in FIG. 3. The cover also has vertically disposed flat front walls 68a and an identical back wall 68b, as shown in FIGS. 4 and 5. A portion of the front wall 68a is recessed as shown at 70a in FIGS. 4 and 5. The back wall has a similar recess depicted at 70b. The arm portions 36a and 36b of the bracket 30 cooperate with the side walls 66a and 66b of the cover to prevent rotation of the cover relative to the bracket when the shaft 50 is rotated. Both the front wall 70a and the back wall 70b are provided with slots 72a (FIGS. 2 and 5) and 72b (FIG. 5), respectively. The slots 72a and 72b each extend vertically from an opening at the bottom of the associated recess 70a or 70b to an enlarged aperture 74a or 74b. The width of the slots 72a and 72b is less than the diameter of the shaft 50, as best illustrated in FIG. 2. The cover 60 is attached to the shaft 50 by placing the cap over the shaft with the open ends of each of the slots 72a and 72b resting over portions of the shaft on either side of the bracket arm portions 36a and 36b. A downward pressure on the cover 60 will temporarily elastically deflect a portion of the cover to permit the shaft 50 to enter the slots 72a and 72b. As the downward pressure is continued, the shaft 50 will advance along the slots 72a and 72b until the shaft enters into the enlarged apertures 74a and 74b. When the shaft 50 is seated in the enlarged apertures 74a and 74b, the elastically deflected portion of the cover will relax partially or totally (depending on the diameter of the apertures), to secure the cap in position. Removal of the cover is accomplished by manually grasping the cover at the lower portion 76a and 76b of the side walls 66a and 66b, respectively and applying an upward force. The upward force similarly elastically deflects the cover 60 to permit the shaft 50 to travel along the slots 72a and 72b. An alternate cover 60' is depicted in FIGS. 6 through 8. The alternate cover has a inner compartment 62' defined by a rectangular top 64', a flat rectangular side walls 66a' and 66b', a flat front wall 68a' and flat a back wall 68b'. The cover 60' is also provided with flanges 78a through 78d (FIG. 8) which provide further protection to the lifting mechanism 24 against the environment. The flanges 78a through 78d deflect resiliently to permit removal and attachment of the cover 60'. The flanges 78a through 78d also help to secure the cover 60' against unintentional separation from the lifting jack 10. The flanges 78a through 78d are secondary, however, to the sloted walls 68a' and 68b' which walls offer the primary resistance against removal of the cover 60. A first bevel gear 80 (FIGS. 4, 5 and 6) is pivotally mounted to the shaft 50 between the bushings 42a and 42b. The gear 80 is keyed or is otherwise constrained to rotate with the shaft 50. A second bevel gear 82 is provided at a right angle to the first gear 80 and in engagement with the first gear. The second gear 82 rests on a thrust bearing 83 which rests on the central portion 32 of the bracket 30. A lead screw 84 (FIGS. 3 and 5) is fastened at one of its ends to the second gear 82. The lead screw 84 extends downwardly from the gear 82 through suitable apertures, not illustrated, in the thrust bearing 83, in the central portion 32 of the bracket 30 and in the plate 26. The lead screw 84 extends downwardly along the common longitudinal axis of the frame members 18 and 22 partly through the center of the frame members. A ball bearing assembly 86 is supported on a shoulder 88 of the lead screw 84 located below the plate 26. As will be explained later, the shoulder 88 supports the load that is to be lifted by the jack 10. A nut 90 (FIGS. 5 and 9) is interconnected with the first tubular member 18 near its uppermost end 92. In the example illustrated, the nut 90 is provided with an annular shoulder 94. The shoulder 94 cooperates with several tabs 96a through 96d, each extending from the member 18. The tabs 96a through 96d lock the nut 90 in position and prevent the nut 90 from rotating relative to the frame member 18. In the example illustrated, the tabs 96a through 96d are formed integrally with the first frame member and are temporarily elastically deflected for attachment of the nut 90. The nut 90 is provided with an internal thread, not illustrated but well known in the art, which cooperates with an external thread 98 on the lead screw 84. When the lead screw 84 is rotated, it translates along its longitudinal axis relative to the nut 60. As shown in FIG. 5, an aperture 100 is provided in the upper portion 102 of the cylindrical wall of the second frame member 22. A grease fitting 104 is provided in the aperture 100 to permit grease to be tapped into the interior of the second frame member 22. The grease is used to lubricate the inner wall 106 of the second frame member 22 and the outer wall 108 of the first frame member 18 as well as portions of a lifting mechanism 24 within the frame members 18 and 22. A bracket 110, illustrated in FIGS. 1, 2 and 5, is provided for interconnecting the second frame member 22 of the lifting jack with a load. The bracket 110 has a first bracket member consisting of a U-shaped stamping 112. As shown in FIG. 5, a pair of identical partial circular cutaways 114a and 114b are provided in the arms of the stamping 112. The bracket 110 is welded to the second frame member 22 by means of welds 116. An aperture 118 is provided in the central portion of the stamping 112. The bracket 110 has a second bracket member consisting of a length of tube 120. The tube 120 is welded, as shown at 122, to the stamping 112 so that the passageway therethrough is aligned with the aperture 118. The tube 120 is further provided with aligned apertures 132a and 132b in its rectanglar walls. A chain 124 (FIG. 1) is fastened at one of its ends 126 to the stamping 112 of the bracket 110. The other end of the chain 124 is fastened to a ring 128 which is interconnected with one end of a locking pin 128. The pin 128 is selectively insertable into apertures 132a and 132b. Also illustrated in the drawing in FIGS. 1, 2 and 5 is a shaft 134 which is interconnected with the load. For ease of illustration, only a portion of the shaft 134 is shown in FIGS. 1 and 2. The portion of the shaft 134 not shown is interconnected, for example, by welds to a load. As illustrated in FIG. 5, the shaft 134 may be provided with apertures aligned 136a and 136b. The pin 130 may be used to temporarily lock the bracket 110 to the shaft 134 by being inserted in apertures 132a and 132b and apertures 136a and 136b. In operation, the weight of the load is transmitted through the bracket 110, the upper frame member 22, the plate 26 and the ball bearing 86 to the shoulder 88 of the lead screw 84. The load is raised by manually imparting a counterclockwise rotation to the crank 48. The counterclockwise rotation of the crank 48 is transmitted through the bevel gears 80 and 82 to the lead screw 84. The lead screw 84 raises the shoulder 88 relative to the nut 90 and, thereby, raises the load relative to the ground. It is readily apparent that the present invention provides an inexpensive manually operable lifting jack that is easy to service. The present invention further provides a lifting jack having an easily removable cover for the drive mechanism. The above constitutes a detailed description of the best mode contemplated by the inventor at the time of filing for carrying out the present invention. Modifications and variations therefrom will be apparent to those skilled in the art and are intended to be included within the scope of the appended claims.

4y

FIELD OF THE INVENTION The invention relates to a process making it possible to connect an electric cable to an end member such as a connector contact. The invention also relates to an end member usable for performing this process. BACKGROUND OF THE INVENTION The invention mainly applies to the connection of electric cables having a light metal, such as aluminium, core, covered by an insulating sheath. However, it can also be used for the connection of cables, whose core is made from any other material such as copper, particularly when it is desirable to have a sealing of the connection and/or when it is wished for the connection to take place in a non-aggressive manner for the cable. In industries such as the aeronautical industry requiring considerable electric cable lengths and for which financial and/or weight gains are desired, certain large cross-section, copper core cables have for some time been replaced by aluminium core cables. Thus, despite the need to use aluminium core cables with a larger cross-section for compensating a reduced conductivity compared with that of copper, the mass balance gives a gain of approximately 50%. In order to take greater advantage of the weight gain resulting from the use of aluminium core cables, it would be logical to also replace smaller cross-section copper core cables by aluminium core cables. This more particularly relates to the copper core cables between gauge 10 (4.9 mm 2 cross-section) and gauge 24 (0.2 mm 2 cross-section). However, although the tensile strength difference between the two materials causes no particular problems with cables with a cross-section greater than 5 mm 2 , it becomes critical for cables having a smaller cross-section. Thus, the forces exerted on the cables, particularly when producing cable bundles, may then be prejudicial to the electrical continuity of the circuits and therefore to the safety of aircraft. Another problem relates to the sensitivity of aluminium to chemical attacks. This sensitivity makes it necessary for the connection between the aluminium cable and the copper contact to be tight, so as to insulate the aluminium from the ambient medium, which is not necessary when a copper cable is used. However, bearing in mind the larger diameter of aluminium core cables compared with copper core cables for an equivalent resistivity, any diameter increase of the contacts for ensuring the sealing and tensile strength of the connection makes it difficult or even impossible to use the standardized tools necessary for the fitting and unlocking of contacts, when use is made of the most widely used connectors where the contacts are unlocked from the rear. Moreover, an increase in the diameter of the cavities formed on standardized connectors for receiving the standardized contacts is difficult to envisage without a modification to the location of the cavities, as a result of the proximity thereof to the existing connectors. However, a modification to the positions of the cavities would be the equivalent of rendering obsolete all the presently used, standardized connectors. Finally, a change in the connection technology for the use of contacts with unlocking from the front would require important modifications and the creation of novel connectors, which is clearly not desirable. GB-A-977,466 proposes the connection of an electric cable to an end member such as an electric contact by introducing the end of the cable into a blind hole or bore having a uniform diameter and machined in a connection zone of the end member. The outer surface of said connection zone is initially a truncated cone-shaped surface, whose diameter increases towards the open end of the hole. The end member is made from a ductile metal, so that a radial compacting force exerted on the connection zone has the effect of giving the outer surface of said zone a uniform diameter, cylindrical shape. Thus, a mechanical connection is formed, which opposes the separation of the end member and the cable. However, the solution described in GB-A-977,466 is not applicable to an aluminium core cable with a cross-section below 5 mm 2 in view of the limited tensile strength of such a cable. In addition, no matter what the nature of the metal from which the cable is made, the solution described in GB-A-977,466 does not make it possible to obtain a tight connection. The main object of the invention is a process making it possible to connect an electric cable, such as a small cross-section aluminium core cable, to an end member such as an electric contact so as to ensure a stable and reliable electrical connection, a satisfactory mechanical strength and the necessary sealing with respect to the external ambient, without complicating implementation, without rendering obsolete the presently used, standardized connection systems and whilst retaining to the greatest possible extent the use of existing tools. SUMMARY OF THE INVENTION According to the invention, this result is obtained by means of a process for the connection of an electric cable to an end member, whose rear connection part has a blind hole and an outer surface having at least one truncated cone-shaped portion, whose diameter increases towards an open end of the hole, in which: the cable is introduced into the blind hole and the rear connection portion is radially compacted in order to give the outer surface a cylindrical shape, characterized in that use is made of a cable having a core covered with an insulating sheath, the cable is bared over a length smaller than that of the blind hole, the cable is introduced into a stepped blind hole formed from at least two cylindrical sections each having a chamfered entrance end, so that an unbared portion of the cable is received in an entrance section of the hole, the truncated cone-shaped portion of the outer surface being positioned around the entrance section and at least one other section of the hole and the connection zone of the end member is radially compacted by wiredrawing, exerting a tension on said member, so as to pass the connection zone into a calibrated die. As a result of these characteristics, the mechanical connection between the end member and the core of the cable is completed by a mechanical connection between the end member and the insulating sheath. In view of the fact that the latter is generally made from a plastics material having high mechanical and electrical performance characteristics, the mechanical strength is improved and makes it possible to envisage the connection of a light metal core, small cross-section cable. Moreover, the thus formed connection is tight and not aggressive for the cable. In a preferred embodiment of the invention, use is made of an end member having at least one inspection hole issuing into a bottom section of the blind hole and a transparent sealing sleeve is placed in said bottom section prior to the introduction of the cable into the blind hole. The inspection hole makes it possible to treat the interior of the blind hole before positioning therein the transparent sealing sleeve. As a result of the transparency of the sleeve, it also makes it possible to check the good fitting of the core of the cable when the connection has been made. The transparent sleeve then maintains the seal of the connection. Advantageously and more particularly when using a cable with a light metal core, an interface ring made from an electrically conductive material such as silver is placed in an intermediate section of the hole before installing the transparent sealing sleeve in the bottom section and before introducing the cable into the blind hole. This interface ring serves to improve the electrical contact between the cable core and the end member whilst compensating the expansion difference between the materials forming these two parts. To facilitate the introduction of the cable into the blind hole, whilst avoiding any need for foolproofing, the interface ring is chamfered towards the inside at its two ends. The invention also relates to an end member usable during the implementation of the connection process defined hereinbefore. More specifically, it proposes an end member to be fitted by radial compacting onto the end of an electric cable, said member having a front portion and a rear connection portion, the latter having a blind hole able to receive one end of the cable, and an outer surface having at least one truncated cone-shaped portion, whose diameter increases towards an open end of the blind hole, characterized in that the end member is intended to be fitted on the end of a cable having a core covered with an insulating sheath, bared over a length smaller than that of the blind hole, the latter being stepped and formed from at least two cylindrical sections, each having a chamfered entrance end, an entrance section of the hole being able to receive an unbared portion of the cable, the truncated cone-shaped portion of the outer surface being located around the entrance section and at least one other section of the hole, and the front portion has a shoulder directed towards the rear connection portion able to serve as an anchoring means for the tension device, for the radial compacting of the rear connection portion by wiredrawing. When the blind hole formed in the connection zone of the end member comprises an entrance section, an intermediate section and a bottom section, the outer surface of said hole has a cylindrical section surrounding the bottom section of the hole and a truncated cone-shaped section surrounding the intermediate section and the entrance section of the hole. The invention is described in greater detail hereinafter relative to a non-limitative embodiment and with reference to the attached drawings, wherein show: BRIEF DESCRIPTION OF THE DRAWING FIG. 1 a partial longitudinal sectional view of an end member such as an electric contact for connection to the end of an electric cable. FIGS. 2A to 2H longitudinal sectional views diagrammatically illustrating the main stages of the realization of the connection process according to the invention. DESCRIPTION OF THE PREFERRED EMBODIMENT FIG. 1 shows an end member 10 such as an electric contact, prior to its connection to the end of an electric cable 12 formed from a core 14 and an insulating sheath 16. The core 14 of the cable 12 can be made from a random metal, although the invention is advantageously applicable to the case where said core is made from a light metal such as aluminium. The insulating sheath 16 is made from a plastics material having high mechanical and electrical performance characteristics. It covers the core 14 of the cable 12, with the exception of its end, which is bared or stripped over a predetermined length L. The end member 10 is made from an electrically conductive material having good cold deformation characteristics, such as a copper alloy. The end member 10 has a symmetry of revolution about a longitudinal axis and has a standardized front portion 10a strictly identical to the front portion of existing contacts, as well as a rear connection portion 10b, whose shape has been modified in accordance with the invention. In the case where the end member is constituted by an electric contact in the manner illustrated in FIG. 1, the front portion 10a is identical to that of standardized male contacts. However, said front portion 10a can assume other shapes and dimensions in accordance with the envisaged application. These shapes can in particular be those of a female contact or an end fitting. For a reason which will become apparent hereinafter, it is important to observe that the front portion 10a of the end member 10 has a flange 18 defining a shoulder 20 turned towards the rear connection portion 10b. The rear connection portion 10b of the end member 10, which commences immediately to the rear of the shoulder 20, has an outer surface which successively defines, starting from the said shoulder, a uniform diameter, cylindrical portion 22 and a truncated cone-shaped portion 24, whose diameter increases from the cylindrical portion 22 up to the rear end of the member 10. As illustrated by FIG. 1, the length of the truncated cone-shaped portion 24 is substantially double the length of the cylindrical portion 22. Moreover, a stepped blind hole or bore 26 is formed coaxially in the rear connection portion 10b of the end member 10 and extends up to the interior of the flange 18. Starting from the bottom, said bore or hole 26 has a cylindrical bottom section 26a with a relatively small diameter, an intermediate, cylindrical section 26b, whose diameter slightly exceeds that of the bottom section 26a and a cylindrical, entrance section 26c, whose diameter slightly exceeds that of the intermediate section 26b. At their entrance end, each of the cylindrical sections 26a,26b and 26c has a chamfer 28a, 28b and 28c respectively. Outside its end located within the flange 18, the bottom section 26a of the hole 26 is completely located within the cylindrical portion 22 of the outer surface of the rear connection portion 10b. The intermediate section 26b of the hole 26, whose length slightly exceeds that of the bottom section 26a is mainly located within the truncated cone-shaped portion 24 of the outer surface of the rear connection portion 10b and extends slightly into the cylindrical portion 22. Finally, the entrance section 26c of the hole 26 is totally located within the truncated cone-shaped portion 24 and has a length less than that of the cylindrical sections 26a and 26b. It should also be noted that the length L of the bared portion of the cable 12 is predetermined so as to slightly exceed the combined length of the sections 26a and 26b of the hole 26, but is significantly less than the total length of said hole 26. The bottom section 26a of the hole 26 has a calibrated diameter equal to the diameter of the core 14 of the cable 12, increased by a slight clearance and two thicknesses of a transparent sealing sleeve 30 provided for slight force fitting in said bottom section 26a. The transparent sealing sleeve 30 can be manufactured from a tubular, extruded plastics material sheath cut at regular intervals. It has a totally symmetrical shape, so that it can be fitted in the bottom section 26a of the hole 26 without having to carry out a long and costly foolproofing. An inspection hole 32 is made radially in the rear connection portion 10b of the end member 10, so as to issue onto the cylindrical portion 22 of the outer surface of said rear portion 10b and in the bottom section 26a of the blind hole 26. This inspection hole 32 facilitates the treatment of the surface of the blind hole 26, i.e. the optional deposition of protective coatings on said surface, as well as its rinsing. It also makes it possible to visually check the presence of the core 14 of the cable 12 when the connection has been made. The intermediate, cylindrical section 26b of the blind hole 26 has a calibrated diameter equal to the diameter of the core 14 of the cable 12, increased by a very slight clearance and two thicknesses of an interface ring 34. The interface ring 34 is slightly force fitted into the intermediate section 26b of the hole 26. It is machined in a highly conductive material making it possible to improve the contact between the core 14 of the cable 12 (e.g. of aluminium) and the end member 10 (e.g. of a copper alloy). The interface ring 34 also makes it possible to compensate the expansion difference between the materials forming these two parts (expansion coefficient approximately 17 for a copper alloy and approximately 23 for an aluminium alloy). In order to best fulfil these two functions, the interface ring 34 is advantageously made from silver. Thus, the conductivity of silver is satisfactory and its expansion coefficient is approximately 19. It is also an easily machinable and relatively malleable metal. It should be noted that it is sometimes possible to avoid the presence of the interface ring 34. This is in particular the case when the core 14 of the cable 12 is also made from a copper alloy. It is also the case when the interface ring can be replaced by a metal deposit fulfilling the same function within the hole 26. In order to facilitate the introduction of the cable 14, the interface ring 34 has at each of its ends an internal chamfer 36. This symmetrical configuration of the interface ring 34 avoids having to use a long and costly foolproofing during installation. The different stages of the connection of the electric cable 12 to the end member 10 will now be described with successive reference to FIGS. 2A to 2H. Firstly, a certain number of surface treatments are carried out on the end member 10 using conventional procedures. These surface treatments usually consist of a copper coating of all the internal and external surfaces of the member 12, facilitating the adhesion of the other deposits. A nickel coating can also take place on the front portion 10a of the member 10. There can also be either a thin gilding of all the internal and external surfaces of the member 10, or a thick, selective gilding on the front portion 10a of said member. Finally, as stated, a silver deposit can be made within the hole 26, particularly when it is wished to obviate the need for the interface ring 34. The inspection hole 32 permits the escape of the air contained within the hole 26 during electrolytic deposition and facilitates the various rinsing operations. Finally and as illustrated in FIG. 2A, the transparent sealing sleeve 30 is slightly force fitted in the bottom section 26a of the hole 26. This operation is facilitated by the presence of the chamfer 28a at the entrance of the section 26a. When completed, the transparent sealing sleeve 30 extends over the entire length of the bottom section 26a and thus tightly caps the inspection hole 32 (FIG. 2B). The interface ring 34 is slightly force fitted in the intermediate section 26b of the hole 26. This operation is facilitated by the chamfer 28b located at the entrance of the section 26b. When completed, the interface ring 34 occupies the entire length of the intermediate section 26b. Into the hole 26, equipped with the sleeve 30 and the ring 34, is then introduced the partly bared end of the cable 12, as illustrated in FIG. 2B. As the length L of the bared portion of the cable 12 is less than the total length of the hole 26 and scarcely exceeds the combined length of the sections 26a and 26b of said hole, the end of the unbared portion of the cable 12 is located in the interior of the entrance section 26c of the hole 26 in the vicinity of the chamfer 28b, when the end of the cable 10 abuts against the bottom of the hole. It should be noted that the introduction of the cable 10 is facilitated, for its core 14, by the chamfer 36 formed at the entrance of the interface ring 34 and, for its sheath 16, by the chamfer 28c formed at the entrance of the entrance section 26c of the hole 26. The penetration of the end of the core 14 into the transparent sealing sleeve 30 causes no particular problem, as a result of the internal diameter of said sleeve being slightly larger than the internal diameter of the interface ring 34. It is visually checked through the inspection hole 32 through the transparent sleeve 30. As is also illustrated by FIG. 2c, the introduction of the end of the cable 12 into the end member 10 is preceded or followed by the putting into place of the end member 10 in the crimping or swaging tool illustrated in a very diagrammatic manner. This crimping tool comprises pliers 38 and a calibrated die 40. The pliers 38 are formed by at least two jaws locking the end member 10 around the cylindrical portion 22 of its outer surface, so that it can bear on the shoulder 20, as illustrated in FIG. 2D. The die 40 is also formed from two half-shell portions, which are closed on the cylindrical portion 22 of the outer surface of the end member 10, when the pliers 38 are closed in the manner illustrated by FIG. 2D. This is followed by the radial compacting of the rear connection portion 10b of the end member 10 by wiredrawing, as illustrated by FIGS. 2E and 2F. As indicated by the arrows F therein, this wiredrawing or crimping operation is carried out by exerting a tensile stress on the end member 10, along the axis thereof, by means of the pliers 38, so as to pass over its entire length the rear connection portion 10b through the calibrated die 40. This operation transforms the outer surface of the rear connection portion 10b into a cylindrical surface, whose uniform diameter is substantially equal to the initial diameter of the cylindrical portion 22. Thus, the intermediate section 26b and the entrance section 26c of the hole 26 are given truncated cone shapes, whose diameter decreases towards the open end of the hole 26. The deformation of the intermediate section 26b of the hole leads to an identical deformation of the interface ring 34. Consequently and as illustrated in FIG. 2G, when this wiredrawing operation is at an end, there is a mechanical connection both between the end member 10 and the core 14 of the cable 12 and between the end member 10 and the cable sheath 16. This mechanical connection prevents any accidental tearing away of the end member and ensures an adequate mechanical strength when the core 14 of the cable 12 has a small diameter and is formed from a light metal such as aluminium. Moreover, the mechanical strength obtained between the end member 10 and the sheath 16 of the cable 12 ensures the sealing of the connection, together with the transparent sealing sleeve 30 to the right of the inspection hole 32 (FIG. 2H). Thus, a connection is obtained which is particularly appropriate for the use of an aluminium core cable, but whose sealing and non-aggressive character make it possible to envisage its application in the case of a cable having a core made from any other material and in particular copper.

4y

BACKGROUND OF THE INVENTION [0001] The invention relates to a coupling device for connecting an electrical/electronic structural part, in particular a sensor, having a substrate, in particular a circuit board, wherein the coupling device comprises at least one electrical connection for the making of electrical contact and at least one damper element for the decoupling of movement. [0002] Furthermore, the invention relates to an assembly having at least one electrical/electronic structural part, in particular a sensor, which can be arranged on a substrate, in particular a circuit board, and having a coupling device for connecting the structural part to the substrate, wherein the coupling device comprises at least one electrical connection for the making of electrical contact and at least one damper element for the decoupling of movement. [0003] Finally, the invention relates to a method for producing an assembly, in particular such as that described above, wherein the assembly comprises at least one electrical/electronic structural part, in particular a sensor, which can be arranged on a substrate, in particular a circuit board, and a coupling device for connecting the structural part to the substrate, wherein the coupling device comprises at least one electrical connection for the making of electrical contact and at least one damper element for the decoupling of movement. [0004] Coupling devices of the type mentioned at the beginning and a corresponding assembly with a coupling device and a method for producing the latter are known from the prior art. Thus it is known in the case of vibration-sensitive structural parts, such as for example in the case of sensors and in particular in the case of micromechanical sensors, to attach them to a substrate by means of a movement-decoupling coupling device. Within the scope of this application, the decoupling of movement should be understood as meaning mechanical decoupling, which serves primarily for decoupling vibrations occurring (vibration decoupling), but may also serve for compensating for tolerances, in particular for compensating for stresses occurring during operation. Thus, for example, there is often the problem that stresses occur between the structural part and the substrate, caused for example by different coefficients of thermal expansion, so that the structural part and the substrate expand/move differently when heated and, as a result, they become stressed with respect to each other at their points of attachment. In the worst case, this may lead to the rupturing of connecting points and consequently to the failure of the structural part. [0005] DE 10 2006 002 350 A1 discloses an inertial sensor assembly in which a sensor module is arranged on a carrier substrate with an elastically deformable coupling element interposed, wherein the material of the damper is injected into a gap present between the sensor module and the carrier substrate in the manner of a frame around the sensor module. The sensor module is then connected by means of bonding wires to a circuit arranged on the carrier substrate. It is therefore known that the coupling device is formed as two parts. SUMMARY OF THE INVENTION [0006] According to the invention, it is provided that the electrical connection is formed by a punched mesh and the punched mesh is encapsulated at least in certain regions by a damping mass as a damper element. It is therefore provided that the electrical connection of the coupling device between the substrate and the structural part is formed by a punched mesh. Punched meshes are generally known to a person skilled in the art and allow a stable electrical connection in a simple manner. According to the invention, the punched mesh is encapsulated at least in certain regions by a damping mass in such a way that the damper element is formed. As a result, the punched mesh and the damper element form a unit or a compact, almost one-part coupling device. The encapsulation of the punched mesh with the damping mass has the effect on the one hand that the punched mesh is given greater stability and on the other hand that a damping effect is provided. The fact that the punched mesh itself has a damping effect as a result of the damping mass surrounding it and the fact that the damping mass itself, which is formed as a damping element, is therefore preferably itself in direct contact with the substrate and the structural part, at least in certain regions, means that a decoupling of movement is brought about between the substrate and the structural part. [0007] Advantageously, the punched mesh forms at least in certain regions at least one spring element. Advantageously, the punched mesh has at least in certain regions a three-dimensional structure for this purpose. Thus, the spring element may, for example, be formed by a web running obliquely in relation to the rest of the punched mesh or by a bent-around spring tongue that is free at one end. Being formed in this advantageous way provides a spring-mass system with damping which can be arranged between the substrate and the structural part. [0008] Expediently, the punched mesh has contact plates that are exposed at least on one side. At least the contact plates are therefore not encapsulated on all sides by the damping mass. Rather, the contact areas rest on the damping element or on the damping mass, wherein one side, namely the side having a contact area, is freely accessible. [0009] Advantageously, the damping mass is silicone or another material having similar properties. [0010] The assembly according to the invention is distinguished by a coupling device such as that described above. It is consequently provided that the assembly comprises a coupling device by means of which the structural part can be arranged on the substrate. This provides a particularly favorable decoupling of movement, which permanently ensures the functional capability of the assembly. [0011] According to an advantageous development, it is provided that the structural part has a housing, in particular an LGA housing (Land Grid Area housing) with at least one electrical contact, which rests on the contact plate or on the contact area of the punched mesh. The resting of the electrical contact on the contact area of the punched mesh establishes the electrical connection between the structural part and the substrate. [0012] The contact is preferably soldered to the contact area. As a result, the structural part is soldered and fixedly connected to the coupling element. The coupling device can expediently also be connected correspondingly to the substrate, in particular to the circuit board, preferably by soldering. On account of the advantageous coupling device, vibrations and/or stresses occurring are compensated or eliminated, whereby the forces acting on the soldered connection(s) do not cause the soldered connection to be destroyed. [0013] Furthermore, it is provided that at least one electrical/electronic component of the structural part is arranged on the damper element. In this case, the coupling device is consequently no longer provided as an independent structural element of the assembly but rather as an integrated/integral element. The damper element of the coupling device serves here as a carrier for a component of the structural part and consequently forms a constituent part of the structural part. The direct arrangement of the component on the damper element provides a particularly compact assembly. [0014] Expediently, the component is electrically connected or operatively connected to the contact area/the contact plate of the punched mesh by means of at least one bonded connection. Consequently, it is no longer intended that the electrical contact with the structural part should be made by way of a housing of the structural part but instead it can be made with respect to the punched mesh directly by the corresponding component of the structural part. A number of contact plates are expediently provided. [0015] Finally, it is provided that the coupling device is integrated at least in certain regions with the component and the contact plate in a molded housing. In other words, in this case the housing of the structural part is applied directly to the coupling device or to the damping element and/or the component, for example by encapsulation and/or overmolding. This makes it possible to create a particularly compact and easy-to-handle unit which is immune to vibrations and/or temperature-induced stresses. [0016] The method according to the invention is distinguished by the fact that the electrical connection is formed by a punched mesh, and the punched mesh is encapsulated at least in certain regions with a damping mass to form the damper element. To do so, first the punched mesh is punched out from a base material by a punching operation and at the same time or subsequently brought into the desired shape by a stamping and/or bending operation. Subsequently, the punched mesh is arranged in a mold which forms the negative of the damper element to be created. In the mold, the damping mass is injected at least in certain regions around the punched mesh. The mold thereby gives the damper element its later contour. [0017] According to an advantageous development, it is provided that a housing of the structural part is soldered to the punched mesh. Corresponding electrical contacts provided on the housing are of course thereby soldered to the punched mesh, and in particular to exposed contact plates of the punched mesh. As a result, on the one hand the electrical contact between the structural part and the punched mesh is realized, and on the other hand the housing, and consequently also the structural part, is attached to the punched mesh or to the coupling device. Correspondingly, the punched mesh is soldered at a different point to the substrate, expediently to corresponding mating contacts of the substrate, thereby establishing a connection between the structural part and the substrate that can withstand loading. [0018] Advantageously, at least one electrical/electronic component of the structural part is arranged on the damper element and is electrically connected to the punched mesh. For the connection, preferably bonded connections are established. It is expedient in this case to dispense with an electrical connection between the housing and the punched mesh, since then the component is (already) electrically connected directly to the punched mesh. [0019] To protect the component and the bonded connections and to complete the structural part, preferably a housing is finally produced by a molding operation, so that at least the component and the bonded connections, and expediently also a further region of the damper element or of the coupling device, are housed. Preferably, the side of the coupling device having the component is completely covered by the molded housing. [0020] Altogether, a particularly favorable and easy-to-produce mechanical decoupling of movement or decoupling of vibration and stress is ensured in this way between the structural part and the substrate, wherein the coupling device preferably forms an integral constituent part of the structural part or is produced as such. BRIEF DESCRIPTION OF THE DRAWINGS [0021] The invention is to be explained in more detail below on the basis of exemplary embodiments. In the figures: [0022] FIGS. 1A to 1D show steps for producing an advantageous coupling device, [0023] FIGS. 2A and 2B show the coupling device with an electrical/electronic structural part in different views, [0024] FIG. 3 shows an alternative embodiment of the coupling device, [0025] FIG. 4 shows the coupling device as an integral constituent part of the structural part and [0026] FIG. 5 shows the structural part with the advantageous coupling device in a perspective representation. DETAILED DESCRIPTION [0027] FIGS. 1A to 1D show different steps for producing an advantageous coupling device 1 . Firstly, a punched mesh 3 is produced from a copper sheet 2 by punching out. In the present exemplary embodiment, the punched mesh 3 has a substantially square frame 4 , within which a multiplicity of square-shaped contact plates 5 and a web 6 extending over almost the entire width of the punched mesh 3 are arranged and are connected to the frame 4 by means of connecting webs 7 . The web 6 is centrally arranged, while the contact plates 5 are arranged on both sides of the web 6 , respectively running in two rows parallel to the web, wherein the row of contact plates 5 respectively lying closer to the web is generally denoted hereafter by 8 and the row of contact plates 5 respectively lying further to the outside is generally denoted hereafter by 9 . [0028] In a second step, according to FIG. 1B , the punched mesh 3 is re-shaped by a bending process in such a way that the outer-lying rows 9 of the contact plates 5 lie in a plane at a distance from the inner-lying rows 8 and the web 6 . In other words, in the present exemplary embodiment the punched mesh 1 is given a substantially U-shaped cross section. It is of course also conceivable in this respect to carry out the punching operation and the bending operation simultaneously or substantially simultaneously in one punching-bending step. The U shape of the punched mesh 3 expediently does not have members that are perpendicular to one another, but members that run at an angle, which run from the connecting webs 7 between the row 9 of outer-lying contact plates and the row 8 of inner-lying contact plates 5 . This angled form gives the punched mesh 3 resilient properties, wherein said connecting webs 7 between the rows 8 and 9 respectively form spring elements 10 of the punched mesh 3 . [0029] In a step which then follows, the punched mesh 3 is encapsulated in certain regions by a damping mass 11 in such a way that the damping mass 11 forms a damper element 12 . In particular, the spring elements 10 are encapsulated at least substantially completely. The damper element 12 likewise has a square contour. The contact plates 5 of the outer-lying rows 9 thereby rest on an upper side 13 of the damper element 12 , so that their respective side that is facing away from the damper element and is exposed forms a contact area 14 . There is a corresponding situation on the underside 15 of the damper element 12 , on which the web 6 and the contact plates 5 of the inner-lying rows 8 rest. Advantageously, the damper element 12 or the damping mass 11 consists at least substantially of silicone. [0030] In a final step according to FIG. 1D , the connecting webs 7 running in the parallel planes and the frame 4 are separated and the punched mesh 3 is thereby singulated. Only the connecting webs 7 forming the spring elements 10 are preserved. These later form the electrical connection 25 from an electrical/electronic structural part arranged on the upper side 13 to a substrate on which the coupling device 1 may be arranged by means of the underside 15 . [0031] The advantageous coupling device 1 , as it is represented in FIG. 1D , offers both an electrical connection and a spring-mass system with a damper in a simple way. [0032] The singulating of the punched mesh 3 is expediently performed by one or more punching operations. This preferably involves moving a punching tool substantially perpendicularly in relation to the upper side 13 or the underside 15 , whereby a force is respectively applied in the direction of the damping mass to the connecting webs to be separated. Since the contact plates 5 , and consequently the connecting webs to be separated, are respectively arranged outside the damping mass 11 , the punching tool directly applies a force in the direction of the damping mass 11 to the connecting webs. The force and the rate of advancement of the punching tool are preferably chosen in this case in such a way that the damping mass is merely elastically deformed during the punching operation. As a result, the separated connecting webs can subsequently be removed particularly easily from the damping mass 11 or they detach themselves. It may possibly also be provided that the force and/or the rate of advancement are chosen in such a way that the connecting webs are driven into the damping mass 11 during the punching operation, so that the damping mass 11 is also plastically deformed. In the latter case, the detached connecting webs may subsequently remain in the damping mass 11 . As a result, the damping property of the coupling device as a whole can be further changed or influenced. The electrical connections 25 lying in the damping mass 11 are intended to remain, and consequently also do not have to be taken into consideration in the punching operation. [0033] Advantageously, a multiplicity of punched meshes 3 are provided, forming a punched mesh matrix, and preferably held by a common frame and separated from one another by a separate punching operation or during the punching operation described above, which serves for singulating the respective punched mesh 3 , and are divided into individual punched meshes 3 , as represented by way of example in FIG. 1D . Consequently, a multiplicity of the advantageous coupling devices 1 according to the exemplary embodiment of FIG. 1D can be produced in a simple way. It is particularly advantageous if production does not involve encapsulating a single punched mesh 3 with damping mass but instead simultaneously encapsulating the punched meshes of a punched mesh matrix (also known as a punched mesh array) with damping mass and subsequently singulating them. [0034] In order to connect or attach an electrical/electronic structural part particularly easily to the coupling device 1 , advantageously soldering paste is respectively applied to the contact areas 14 . As a result, rapid mounting of a corresponding structural part on the coupling device is ensured. [0035] FIGS. 2A and 2B show the coupling device 1 in a side view in the direction of the longitudinal extent of the web 6 ( FIG. 2A ) and perpendicular thereto ( FIG. 2B ). An electrical/electronic structural part 16 , which is formed as a sensor 17 with movement-sensitive micromechanics, has been applied here to the coupling device 1 known from FIG. 1D . All that is shown here of the sensor 17 is a housing 18 , which is formed as a molded housing 19 and has on its side facing the coupling device 1 electrical contacts, which rest on the contact areas 14 of the coupling device 1 . The housing 18 is advantageously adhesively attached to the damper element 12 . The assembly 20 formed as a result, consisting of the coupling device 1 and the structural part 16 , can then be soldered for example on a substrate, such as for example on a circuit board, wherein the connection between the coupling device 1 and the housing 18 is also established in the same step by soldering with the aid of the soldering paste 21 . The advantageous connection of the structural part 16 to the circuit board by way of the coupling device 1 has the effect that the structural part 16 is decoupled in terms of vibration, so that the sensitive micromechanics of the sensor 17 are not influenced in an unwanted manner by vibrations. In addition, the functional capability is ensured to the extent that no stresses that could destroy the soldered connections occur between the sensor 17 and the circuit board, for example on account of tolerances during the mounting or due to temperature-induced material changes. [0036] FIG. 3 shows a further embodiment of the coupling device 1 given by way of example, before the singulation of the punched mesh 3 . As a difference from the exemplary embodiment known from FIG. 1C , the punched mesh 3 does not have a web 6 . Provided instead are a number of rows of five contact plates each, which extend over the width of the punched mesh 3 and are connected to one another by way of connecting webs 7 only in the respective row. Of course, any number of different configurations of the punched mesh 3 are conceivable. [0037] FIG. 4 shows an advantageous exemplary embodiment of a development of the assembly 20 . According to this exemplary embodiment, the coupling device 1 forms an integral constituent part of the structural part 16 or of the sensor 17 . For this purpose, in the present case two components 22 , 23 of the sensor 17 are arranged on the damper element 12 (on the upper side 13 ) between the outer-lying rows 9 of the contact plates 5 . [0038] Subsequently, the components 22 and 23 are advantageously electrically contacted or connected to the contact areas 14 of the punched mesh 3 by means of bonded connections. In the step which then follows, the coupling device 1 and the components 22 , 23 located thereupon and the contact plates 5 are housed by a molding process, whereby a molded housing 24 is formed. Subsequently, the desired connecting webs 7 are removed and the punched mesh 3 is singulated and the frame 4 removed. As a result, on the one hand the components 22 , 23 and the bonded connections are protected from external influences, and on the other hand a particularly compact and easy-to-handle assembly 20 is offered. [0039] The fact that the molded housing 24 is formed directly on the coupling device 1 , by an injecting and/or molding operation, means that the coupling device 1 is integrated in the assembly 20 . The assembly 20 configured in this way must then just be attached to a substrate—not represented here—, for example by means of soldering. In a further exemplary embodiment, not represented here, the circuit board or the substrate likewise forms a constituent part of the assembly 20 , so that, by means of a circuit board, the assembly 20 can be produced and offered as a structural unit. [0040] In principle, it is also conceivable to arrange the components 22 , 23 on the underside 15 of the damper element 12 , in particular on the copper web 6 , in order to make the creation of the bonded connections easier.

4y

RELATED APPLICATIONS [0001] This application is a continuation of application Ser. No. 10/732,326 filed Dec. 10, 2003, which in turn is a continuation-in-part of application Ser. No. 10/372,017, filed Feb. 21, 2003, now U.S. Pat. No. 6,689,262, which claims the benefit of U.S. Provisional Application No. 60/358,534, filed Feb. 22, 2002, each of which is hereby fully incorporated herein by reference. FIELD OF THE INVENTION [0002] This invention relates to the electrolytic generation of microbubbles of oxygen for increasing the oxygen content of flowing water. This invention also relates to the use of superoxygenated water to enhance the growth and yield of plants. The flow-through model is useful for oxygenating water for hydroponic plant culture, drip irrigation and waste water treatment. BACKGROUND OF THE INVENTION [0003] Many benefits may be obtained through raising the oxygen content of aqueous media. Efforts have been made to achieve higher saturated or supersaturated oxygen levels for applications such as the improvement of water quality in ponds, lakes, marshes and reservoirs, the detoxification of contaminated water, culture of fish, shrimp and other aquatic animals, biological culture and hydroponic culture. For example, fish held in a limited environment such as an aquarium, a bait bucket or a live hold tank may quickly use up the dissolved oxygen in the course of normal respiration and are then subject to hypoxic stress, which can lead to death. A similar effect is seen in cell cultures, where the respiring cells would benefit from higher oxygen content of the medium. Organic pollutants from agricultural, municipal and industrial facilities spread through the ground and surface water and adversely affect life forms. Many pollutants are toxic, carcinogenic or mutagenic. Decomposition of these pollutants is facilitated by oxygen, both by direct chemical detoxifying reactions or by stimulating the growth of detoxifying microflora. Contaminated water is described as having an increased biological oxygen demand (BOD) and water treatment is aimed at decreasing the BOD so as to make more oxygen available for fish and other life forms. [0004] The most common method of increasing the oxygen content of a medium is by sparging with air or oxygen. While this is a simple method, the resulting large bubbles produced simply break the surface and are discharged into the atmosphere. Attempts have been made to reduce the size of the bubbles in order to facilitate oxygen transfer by increasing the total surface area of the oxygen bubbles. U.S. Pat. No. 5,534,143 discloses a microbubble generator that achieves a bubble size of about 0.10 millimeters to about 3 millimeters in diameter. U.S. Pat. No. 6,394,429 (“the '429 patent”) discloses a device for producing microbubbles, ranging in size from 0.1 to 100 microns in diameter, by forcing air into the fluid at high pressure through a small orifice. [0005] When the object of generating bubbles is to oxygenate the water, either air, with an oxygen content of about 21%, or pure oxygen may be used. The production of oxygen and hydrogen by the electrolysis of water is well known. A current is applied across an anode and a cathode which are immersed in an aqueous medium. The current may be a direct current from a battery or an AC/DC converter from a line. Hydrogen gas is produced at the cathode and oxygen gas is produced at the anode. The reactions are: [0000] AT THE CATHODE: 4H 2 O+4 e − →4OH − +2H 2 [0000] AT THE ANODE: 2H 2 O→O 2 +4H + +4 e − [0000] NET REACTION: 6H 2 O→4OH − +4H + ++2H 2 +O 2 [0000] 286 kilojoules of energy is required to generate one mole of oxygen. [0006] The gasses form bubbles which rise to the surface of the fluid and may be collected. Either the oxygen or the hydrogen may be collected for various uses. The “electrolytic water” surrounding the anode becomes acidic while the electrolytic water surrounding the cathode becomes basic. Therefore, the electrodes tend to foul or pit and have a limited life in these corrosive environments. [0007] Many cathodes and anodes are commercially available. U.S. Pat. No. 5,982,609 discloses cathodes comprising a metal or metallic oxide of at least one metal selected from the group consisting of ruthenium, iridium, nickel, iron, rhodium, rhenium, cobalt, tungsten, manganese, tantalum, molybdenum, lead, titanium, platinum, palladium and osmium. Anodes are formed from the same metallic oxides or metals as cathodes. Electrodes may also be formed from alloys of the above metals or metals and oxides co-deposited on a substrate. The cathode and anodes may be formed on any convenient support in any desired shape or size. It is possible to use the same materials or different materials for both electrodes. The choice is determined according to the uses. Platinum and iron alloys (“stainless steel”) are often preferred materials due to their inherent resistance to the corrosive electrolytic water. An especially preferred anode disclosed in U.S. Pat. No. 4,252,856 comprises vacuum deposited iridium oxide. [0008] Holding vessels for live animals generally have a high population of animals which use up the available oxygen rapidly. Pumps to supply oxygen have high power requirements and the noise and bubbling may further stress the animals. The available electrolytic generators likewise have high power requirements and additionally run at high voltages and produce acidic and basic water which are detrimental to live animals. Many of the uses of oxygenators, such as keeping bait or caught fish alive, would benefit from portable devices that did not require a source of high power. The need remains for quiet, portable, low voltage means to oxygenate water. [0009] It has also been known that plant roots are healthier when oxygenated water is applied. It is thought that oxygen inhibits the growth of deleterious fungi. The water sparged with air as in the '429 patent was shown to increase the biomass of hydroponically grown cucumbers and tomatoes by about 15%. [0010] The need remains for oxygenator models suitable to be placed in-line in water distribution devices so as to be applied to field as well as hydroponic culture. SUMMARY OF THE INVENTION [0011] This invention provides an oxygen emitter which is an electrolytic cell which generates very small microbubbles and nanobubbles of oxygen in an aqueous medium, which bubbles are too small to break the surface tension of the medium, resulting in a medium supersaturated with oxygen. [0012] The electrodes may be a metal or oxide of at least one metal selected from the group consisting of ruthenium, iridium, nickel, iron, rhodium, rhenium, cobalt, tungsten, manganese, tantalum, molybdenum, lead, titanium, platinum, palladium and osmium or oxides thereof. The electrodes may be formed into open grids or may be closed surfaces. The most preferred cathode is a stainless steel mesh. The most preferred mesh is a 1/16 inch grid. The most preferred anode is platinum and iridium oxide on a support. A preferred support is titanium. [0013] In order to form microbubbles and nanobubbles, the anode and cathode are separated by a critical distance. The critical distance ranges from 0.005 inches to 0.140 inches. The preferred critical distance is from 0.045 to 0.060 inches. [0014] Models of different size are provided to be applicable to various volumes of aqueous medium to be oxygenated. The public is directed to choose the applicable model based on volume and power requirements of projected use. Those models with low voltage requirements are especially suited to oxygenating water in which animals are to be held. [0000] Controls are provided to regulate the current and timing of electrolysis. [0015] A flow-through model is provided which may be connected in-line to a watering hose or to a hydroponic circulating system. The flow-through model can be formed into a tube with triangular cross-section. In this model, the anode is placed toward the outside of the tube and the cathode is placed on the inside, contacting the water flow. Alternatively, the anodes and cathodes may be in plates parallel to the long axis of the tube, or may be plates in a wafer stack. Alternately, the electrodes may be placed in a side tube (“T” model) out of the direct flow of water. Protocols are provided to produce superoxygenated water at the desired flow rate and at the desired power usage. Controls are inserted to activate electrolysis when water is flowing and deactivate electrolysis at rest. [0016] This invention includes a method to promote growth and increase yield of plants by application of superoxygenated water. The water treated with the emitter of this invention is one example of superoxygenated water. Plants may be grown in hydroponic culture or in soil. The use of the flow-through model for drip irrigation of crops and waste water treatment is disclosed. BRIEF DESCRIPTION OF THE DRAWINGS [0017] FIG. 1 is the O 2 emitter of the invention. [0018] FIG. 2 is an assembled device. [0019] FIG. 3 is a diagram of the electronic controls of the O 2 emitter. [0020] FIG. 4 shows a funnel or pyramid variation of the O 2 emitter. [0021] FIG. 5 shows a multilayer sandwich O 2 emitter. [0022] FIG. 6 shows the yield of tomato plants watered with superoxygenated water. [0023] FIG. 7 shows an oxygenation chamber suitable for flow-through applications. FIG. 7A is a cross section showing arrangement of three plate electrodes. FIG. 7B is a longitudinal section showing the points of connection to the power source. [0024] FIG. 8 is a graph showing the oxygenation of waste water. DETAILED DESCRIPTION OF THE INVENTION Definitions [0025] For the purpose of describing the present invention, the following terms have these meanings: [0026] “Critical distance” means the distance separating the anode and cathode at which evolved oxygen forms microbubbles and nanobubbles. [0027] “Critical distance” means the distance separating the anode and cathode at which evolved oxygen forms microbubbles and nanobubbles. [0028] “O 2 emitter” means a cell comprised of at least one anode and at least one cathode separated by the critical distance. [0029] “Metal” means a metal or an alloy of one or more metals. [0030] “Microbubble” means a bubble with a diameter less than 50 microns. [0031] “Nanobubble” means a bubble with a diameter less than that necessary to break the surface tension of water. Nanobubbles remain suspended in the water, giving the water an opalescent or milky appearance. [0032] “Supersaturated” means oxygen at a higher concentration than normal calculated oxygen solubility at a particular temperature and pressure. [0033] “Superoxygenated water” means water with an oxygen content at least 120% of that calculated to be saturated at a temperature. [0034] “Water” means any aqueous medium with resistance less than one ohm per square centimeter; that is, a medium that can support the electrolysis of water. In general, the lower limit of resistance for a medium that can support electrolysis is water containing more than 2000 ppm total dissolved solids. [0035] The present invention produces microbubbles and nanobubbles of oxygen via the electrolysis of water. As molecular oxygen radical (atomic weight 8) is produced, it reacts to form molecular oxygen, O 2 . In the special dimensions of the invention, as explained in more detail in the following examples, O 2 forms bubbles which are too small to break the surface tension of the fluid. These bubbles remain suspended indefinitely in the fluid and, when allowed to build up, make the fluid opalescent or milky. Only after several hours do the bubbles begin to coalesce on the sides of the container and the water clears. During that time, the water is supersaturated with oxygen. In contrast, the H 2 formed readily coalesces into larger bubbles which are discharged into the atmosphere, as can be seen by bubble formation at the cathode. [0036] The first objective of this invention was to make an oxygen emitter with low power demands, low voltage and low current for use with live animals. For that reason, a small button emitter was devised. The anode and cathode were set at varying distances. It was found that electrolysis took place at very short distances before arcing of the current occurred. Surprisingly, at slightly larger distances, the water became milky and no bubbles formed at the anode, while hydrogen continued to be bubbled off the cathode. At distance of 0.140 inches between the anode and cathode, it was observed that the oxygen formed bubbles at the anode. Therefore, the critical distance for microbubble and nanobubble formation was determined to be between 0.005 inches and 0.140 inches. EXAMPLE 1 Oxygen Emitter [0037] As shown in FIG. 1 , the oxygen evolving anode 1 selected as the most efficient is an iridium oxide coated single sided sheet of platinum on a support of titanium (Eltech, Fairport Harbor, Ohio). The cathode 2 is a (fraction ( 1/16)} inch mesh (size 8 mesh) marine stainless steel screen. The anode and cathode are separated by a non-conducting spacer 3 containing a gap 4 for the passage of gas and mixing of anodic and cathodic water and connected to a power source through a connection point 5 . FIG. 2 shows a plan view of the assembled device. The O 2 emitter 6 with the anode connecting wire 7 and the cathode connecting wire 8 is contained in an enclosure 9 , connected to the battery compartment 10 . The spacer thickness is critical as it sets the critical distance. It must be of sufficient thickness to prevent arcing of the current, but thin enough to separate the electrodes by no more than 0.140 inches. Above that thickness, the power needs are higher and the oxygen bubbles formed at higher voltage will coalesce and escape the fluid. Preferably, the spacer is from 0.005 to 0.075 inches thick. At the lower limits, the emitter tends to foul more quickly. Most preferably, the spacer is about 0.050 inches thick. The spacer may be any nonconductive material such as nylon, fiberglass, Teflon®. polymer or other plastic. Because of the criticality of the space distance, it is preferable to have a non-compressible spacer. It was found that Buna, with a durometer measure of 60 was not acceptable due to decomposition. Viton, a common fluoroelastomer, has a durometer measure of 90 and was found to hold its shape well. [0038] In operation, a small device with an O 2 emitter 1.485 inches in diameter was driven by 4AA batteries. The critical distance was held at 0.050 inches with a Viton spacer. Five gallons of water became saturated in seven minutes. This size is suitable for raising oxygen levels in an aquarium or bait bucket. [0039] It is convenient to attach a control circuit which comprises a timer that is thermostatically controlled by a temperature sensor which determines the off time for the cathode. When the temperature of the solution changes, the resistance of the thermistor changes, which causes an off time of a certain duration. In cool water, the duration is longer so in a given volume, the emitter generates less oxygen. When the water is warmer and therefore hold less oxygen, the duration of off time is shorter. Thus the device is self-controlled to use power most economically. FIG. 3 shows a block diagram of a timer control with anode 1 , cathode 2 , thermistor temperature sensor 3 , timer control circuit 4 and wire from a direct current power source 5 . EXAMPLE 2 Measurement of O 2 Bubbles [0040] Attempts were made to measure the diameter of the O 2 bubbles emitted by the device of Example 1. In the case of particles other than gasses, measurements can easily be made by scanning electron microscopy, but gasses do not survive electron microscopy. Large bubble may be measured by pore exclusion, for example, which is also not feasible when measuring a gas bubble. A black and white digital, high contrast, backlit photograph of treated water with a millimeter scale reference was shot of water produced by the emitter of Example 1. About 125 bubbles were seen in the area selected for measurement. Seven bubbles ranging from the smallest clearly seen to the largest were measured. The area was enlarged, giving a scale multiplier of 0.029412. [0041] Recorded bubble diameters at scale were 0.16, 0.22, 0.35, 0.51, 0.76, 0.88 and 1.09 millimeters. The last three were considered outliers by reverse analysis of variance and were assumed to be hydrogen bubbles. When multiplied by the scale multiplier, the assumed O 2 bubbles were found to range from 4.7 to 15 microns in diameter. This test was limited by the resolution of the camera and smaller bubbles in the nanometer range could not be resolved. It is known that white light cannot resolve features in the nanometer size range, so monochromatic laser light may give resolution sensitive enough to measure smaller bubbles. Efforts continue to increase the sensitivity of measurement so that sub-micron diameter bubbles can be measured. EXAMPLE 3 Other Models of Oxygen Emitter [0042] Depending on the volume of fluid to be oxygenated, the oxygen emitter of this invention may be shaped as a circle, rectangle, cone or other model. One or more may be set in a substrate that may be metal, glass, plastic or other material. The substrate is not critical as long as the current is isolated to the electrodes by the nonconductor spacer material of a thickness from 0.005 to 0.075 inches, preferably 0.050 inches. It has been noticed that the flow of water seems to be at the periphery of the emitter, while the evolved visible bubbles (H 2 ) arise at the center of the emitter. Therefore, a funnel or pyramidal shaped emitter was constructed to treat larger volumes of fluid. FIG. 4 is a cross sectional diagram of such an emitter. The anode 1 is formed as an open grid separated from a marine grade stainless steel screen cathode 2 by the critical distance by spacer 3 around the periphery of the emitter and at the apex. This flow-through embodiment is suitable for treating large volumes of water rapidly. [0043] The size may be varied as required. A round emitter for oxygenating a bait bucket may be about 2 inches in diameter, while a 3-inch diameter emitter is adequate for oxygenating a 10 to 40 gallon tank. The live well of a fishing boat will generally hold 40 to 80 gallons of water and require a 4-inch diameter emitter. It is within the scope of this invention to construct larger emitters or to use several in a series to oxygenate larger volumes. It is also within the scope of this invention to vary the model to provide for low voltage and amperage in cases where the need for oxygen is moderate and long lasting or conversely, to supersaturate water very quickly at higher voltage and amperage. In the special dimensions of the present invention, it has been found that a 6 volt battery supplying a current as low as 40 milliamperes is sufficient to generate oxygen. Such a model is especially useful with live plants or animals, while it is more convenient for industrial use to use a higher voltage and current. Table I shows a number of models suitable to various uses. [0000] TABLE I Emitter Model Gallons Volts Amps Max. Ave Watts Bait keeper 5 6 0.090 0.060 0.36 Livewell 32 12 0.180 0.120 1.44 OEM 2 inch 10 12 0.210 0.120 1.44 Bait store 70 12 0.180 0.180 2.16 Double cycle 2 12 0.180 0.180 2.16 OEM 3 inch 50 12 0.500 0.265 3.48 OEM 4 inch 80 12 0.980 0.410 4.92 Water pail 2 24 1.200 1.200 28.80 Plate 250 12 5.000 2.500 30.00 EXAMPLE 4 Multilayer Sandwich O 2 Emitter [0044] An O 2 emitter was made in a multilayer sandwich embodiment. ( FIG. 5 ) An iridium oxide coated platinum anode 1 was formed into a grid to allow good water flow and sandwiched between two stainless steel screen cathodes 2 . Spacing was held at the critical distance by nylon spacers 3 . The embodiment illustrated is held in a cassette 4 which is secured by nylon bolt 5 with a nylon washer 6 . The dimensions selected were: [0000] cathode screen 0.045 inches thick nylon spacer 0.053 inches thick anode grid 0.035 inches thick nylon spacer 0.053 inches thick cathode screen 0.045 inches thick, for an overall emitter thickness of 0.231 inches thick inches. [0045] If a more powerful emitter is desired, it is within the scope of this invention to repeat the sequence of stacking. For example, an embodiment may easily be constructed with this sequence: cathode, spacer, anode, spacer, cathode, spacer, anode, spacer, cathode, spacer, anode, spacer, cathode. The number of layers in the sandwich is limited only by the power requirements acceptable for an application. EXAMPLE 5 Effect of Superoxygenated Water on the Growth of Plants [0046] It is known that oxygen is important for the growth of plants. Although plants evolve oxygen during photosynthesis, they also have a requirement for oxygen for respiration. Oxygen is evolved in the leaves of the plants, while often the roots are in a hypoxic environment without enough oxygen to support optimum respiration, which can be reflected in less than optimum growth and nutrient utilization. Hydroponically grown plants are particularly susceptible to oxygen deficit in the root system. U.S. Pat. No. 5,887,383 describes a liquid supply pump unit for hydroponic cultures which attain oxygen enrichment by sparging with air. Such a method has high energy requirements and is noisy. Furthermore, while suitable for self-contained hydroponic culture, the apparatus is not usable for field irrigation. In a report available on the web, it was shown that hydroponically grown cucumbers and tomatoes supplied with water oxygenated with a device similar to that described in the '429 patent had increased biomass of about 12% and 17% respectively. It should be noted that when sparged with air, the water may become saturated with oxygen, but it is unlikely that the water is superoxygenated. A. Superoxygenated Water in Hydroponic Culture. [0047] Two small hydroponic systems were set up to grow two tomato plants. Circulation protocols were identical except that the 2½ gallon water reservoir for the Control plant was eroated with and aquarium bubbler and that for the Test plant was oxygenated with a five-inch strip emitter for two minutes prior to pumping. The cycle was set at four minutes of pumping, followed by four minutes of rest. The control water had an oxygen content of about 97% to 103% saturation, that is, it was saturated with oxygen. The test water had an oxygen content of about 153% to 165% saturation, that is, it was supersaturated. The test plant was at least four times the volume of the control plant and began to show what looked like fertilizer burn. At that point the fertilizer for the Test plant was reduced by half. Since the plants were not exposed to natural light but to continuous artificial light in an indoor environment without the natural means of fertilization (wind and/or insects), the experiment was discontinued after three months. At that time, the Test plant but not the Control plant had blossomed. B. Superoxygenated Water in Field Culture. [0048] A pilot study was designed to ascertain that plants outside the hydroponic culture facility would benefit from the application of oxygen. It was decided to use water treated with the emitter of Example 1 as the oxygen carrier. Since water so treated is supersaturated, it is an excellent carrier of oxygen. [0049] Tomato seeds (Burpee “Big Boy”) were planted in one-inch diameter peat and dirt plugs encased in cheese cloth and placed in a tray in a southwest window. Controls were watered once a day with tap water (“Control”) or oxygenated water (“Test”). Both Controls and Test sprouted at one week. After five weeks, the Test plants were an average of 11 inches tall while the Controls were an average of nine inches tall. At this time, May 10, when the threat of frost in Minnesota was minimal, the plants were transplanted to 13 inch diameter pots with drainage holes. Four inches of top soil was added to each pot, topped off with four inches of Scott's Potting Soil. The pots were placed outside in a sunny area with at least eight hours a day of full sun. The plants were watered as needed with either plain tap water (Control) or oxygenated water (Test). The oxygenated water was produced by use of the emitter of Example 1 run for one-half hour in a five-gallon container of water. Previous experiments showed that water thus treated had an oxygen content from 160% to 260% saturation. The Test plants flowered on June 4, while the Controls did not flower until June 18. For both groups, every plant in the group first had flowers on the same day. All plants were fertilized on July 2 and a soaker hose provided because the plants were now so big that watering by hand was difficult. The soaker hose was run for one half to one hour each morning, depending on the weather, to a point at which the soil was saturated with water. One half hour after the soaker hose was turned off, about 750 ml of superoxygenated water was applied to each of the Test plants. [0050] The Test plants were bushier than the Controls although the heights were similar. At this time, there were eight Control plants and seven Test plants because one of the Test plants broke in a storm. On July 2, the control plants averaged about 17 primary branches from the vine stem, while the control plants averaged about 13 primary branches from the vine stem. As the tomatoes matured, each was weighed on a kitchen scale at harvest. The yield history is shown in Table II. [0000] TABLE II Test, grams Control, grams tomatoes from seven tomatoes from eight plants/cumulative Week of: plants/cumulative total total July 27 240 400 August 3 180 420 2910 3310 August 10 905 1325 1830 5140 August 17 410 1735 2590 7730 August 24 3300 5035 2470 10200 August 31 4150 9175 1580 11780 September 15 not weighed 3710 15490 Final Harvest September 24 6435 15620 8895 24385 [0051] The total yield for the eight Control plants was 15620 grams or 1952 grams of tomatoes per plant. [0052] The total yield for the seven Test plants was 24385 grams or 3484 grams of tomatoes per plant, an increase in yield of about 79% over the Control plants. [0053] FIG. 6 shows the cumulative total as plotted against time. Not only did the Test plants blossom and bear fruit earlier, but that the Control plants never caught up to the test plants in the short Minnesota growing season. It should be noted that the experiment was terminated because of predicted frost. All fruits, both green and red, were harvested and weighed at that point. EXAMPLE 6 Flow-Through Emitter for Agricultural Use [0054] In order to apply the findings of example 5 to agricultural uses, an emitter than can oxygenate running water efficiently was developed. In FIG. 7(A) , the oxygenation chamber is comprised of three anodes 1 and cathodes 2 , of appropriate size to fit inside a tube or hose and separated by the critical distance are placed within a tube or hose 3 at 120° angles to each other. The anodes and cathodes are positioned with stabilizing hardware 4 . The stabilizing hardware, which can be any configuration such as a screw, rod or washer, is preferably formed from stainless steel. FIG. 7(B) shows a plan view of the oxygenation chamber with stabilizing hardware 4 serving as a connector to the power source and stabilizing hardware 5 serving as a connector to the power source. The active area is shown at 6 . [0055] This invention is not limited to the design selected for this embodiment. Those skilled in the art can readily fabricate any of the emitters shown in FIG. 4 or 5 , or can design other embodiments that will oxygenate flowing water. One useful embodiment is the “T” model, wherein the emitter unit is set in a side arm. The emitted bubbles are swept into the water flow. The unit is detachable for easy servicing. Table III shows several models of flow through emitters. The voltage and flowrates were held constant and the current varied. The Dissolved oxygen (DO) from the source was 7.1 mg/liter. The starting temperature was 12.2° C. but the flowing water cooled slightly to 11 or 11.5° C. Without undue experimentation, anyone may easily select the embodiment that best suits desired characteristics from Table III or designed with the teachings of Table III. [0000] TABLE III ACTIVE DO OF* ELECTRODE CURRENT, FLOW RATE SAMPLE AT MODEL AREA, SQ.IN. VOLTAGE AMPS. GAL/MINUTE ONE MINUTE 2-Inch “T” 2 28.3 0.72 12 N/A 3-inch “T” 3 28.3 1.75 12 N/A 2-plate Tube 20 28.3 9.1 12 8.4 3-Plate tube 30 28.3 12.8 12 9.6 *As the apparatus runs longer, the flowing water becomes milky, indicating supersaturation. The one-minute time point shows the rapid increase in oxygenation. [0056] The following plants will be tested for response to superoxygenated water: grape vines, lettuce, and radishes in three different climate zones. The operators for these facilities will be supplied with units for drip irrigation. Drip irrigation is a technique wherein water is pumped through a pipe or hose with perforations at the site of each plant to be irrigated. The conduit may be underground or above ground. Since the water is applied directly to the plant rather than wetting the entire field, this technique is especially useful in arid climates or for plants requiring high fertilizer applications. [0057] The superoxygenated water will be applied by drip irrigation per the usual protocol for the respective plants. Growth and yield will be compared to the same plants given only the usual irrigation water. Pest control and fertilization will be the same between test and control plants, except that the operators of the experiments will be cautioned to be aware of the possibility of fertilizer burn in the test plants and to adjust their protocols accordingly. [0058] It is expected that the superoxygenated plants with drip irrigation will show more improved performance with more continuous application of oxygen than did the tomato plants of Example 5, which were given superoxygenated water only once a day. EXAMPLE 7 Treatment of Waste Water [0059] Waste water, with a high organic content, has a high BOD, due to the bacterial flora. It is desirable to raise the oxygen content of the waste water in order to cause the flora to flocculate. However, it is very difficult to effectively oxygenate such water. Using a 4 inch OEM (see Table I) with a 12 volt battery, four liters of waste water in a five gallon pail were oxygenated. As shown in FIG. 8 , the dissolved oxygen went from 0.5 mg/l to 10.8 mg/l in nine minutes. [0060] Those skilled in the art will readily comprehend that variations, modifications and additions may in the embodiments described herein may be made. Therefore, such variations, modifications and additions are within the scope of the appended claims.

4y

BACKGROUND OF THE INVENTION The present invention relates generally to the field of apparatus for moving persons into and out of a vehicle and more specifically relates to an improved construction and arrangement for a rotary wheelchair lift apparatus adapted to receive a conventional type wheelchair for moving a user into and out of a vehicle, such as a van or the like, of the type which incorporates a side-door opening whereby the user can easily and quickly be moved from ground level by an initial vertical lifting movement and then by a rotary pivotal movement into the van via the side-door, and then being able to reverse the procedure with the user having full control of the lift apparatus while sitting in the wheelchair to obviate any requirement to leave the wheelchair at any time. The lift apparatus of the present invention is especially suited to the use by disabled persons confined to a wheelchair mode life-style, such as paraplegics and other such disabled persons. With the advent of our society's desire to participate in various outdoor activities there has been a great expansion in the interest for outdoor recreation particularly in respect to outdoor travel via recreational vehicles, such as recreational vans commonly referred to as RV's. Fortunately, this interest in recreational vehicles has extended itself to disabled persons confined to a wheelchair life-style of living. Such persons including a great number of war veterans have sought to extend their participation in recreation along with others by being able to utilize rather technically sophisticated recreational vans or van conversions which enables the wheelchair user to drive the vehicle under his own control such as by substituting the conventional driver's seat for the wheelchair itself, for example. With this there has been developed a need for an efficient, reliable and safe system which can move the user sitting in his wheelchair into and out of the vehicle with a minimum of effort and yet at a relatively low cost. Heretofore, various types of devices and/or arrangements have been provided to move the user into and out of the vehicle. One such arrangement has been to utilize various ramp or lift mechanisms associated with the rear or side door of the van. However, these arrangements are not especially satisfactory since they require a lot of working area not conducive to limited parking areas and are not as convenient or easy to operate by the user while sitting in the wheelchair. In another arrangement, a rotary type lift apparatus has been provided for use with the side-door of the vehicle, as disclosed in U.S. Pat. No. 3,516,559, for example. In this particular lift apparatus there is not provided the structural and/or functional advantages afforded by the present invention for the reasons which will become apparent hereinafter. SUMMARY OF THE INVENTION The present invention relates to an improved rotary wheelchair lift apparatus which comprises a carriage lift assembly including a platform adapted to receive a wheelchair of standard construction. The carriage lift assembly includes an improved support column sub-assembly which mounts the platform via a plurality of rollers of generally frusto-conical construction adapted for rolling engagement on confronting generally planar surfaces of a support column member for smooth and safe operation with a minimum of "sway" to the platform mounting the wheelchair and with no bending or torquing of the components including the screw drive mechanism. In the invention, the screw drive mechanism is mounted on the vehicle chassis, i.e. 4, and extends generally parallel to the support column member and threadably connects with the carriage lift assembly while moving the lift platform vertically upwardly and downwardly upon energization from a drive mechanism mounted on the vehicle chassis, i.e. 4. The upper end of the drive mechanism is operably connected to another drive motor for rotating the carriage lift assembly about the vertical axis of the column member and into and out of the vehicle via the side-door thereof. In the invention, the respective drive motors operate via gear and pulley mechanisms operable by a control circuit which is energized from the conventional vehicle battery. In the invention, the support column and screw drive mechanism are constructed and arranged to provide a predetermined "lost motion" so that the lift platform can be completely grounded in the down-position to provide stability to the system upon a continued overdrive of the drive motor for the screw mechanism. This "lost motion" or play in the system is approximately 2 inches in respect to travel on the support column so as to accommodate vehicles, such as vans, having a ground-to-floor heighth of between 25 and 27 inches. This then would accommodate one/half or three/quarter or one ton vans. In the invention, there is further provided an improved frame structure for mounting the lift platform which incorporates the control levers for easy access by the user for controlling vertical and rotary movements of the carriage lift assembly. The frame structure further mounts a table-drive assembly operably associated with a stop mechanism mounted on the platform adapted to be automatically raised and lowered in response to vertical movement of the carriage lift for preventing the wheelchair from rolling off the platform during normal use of the lift apparatus. From the foregoing, it will be seen that the present invention provides an improved rotary wheelchair lift apparatus which is of a compact, safe and reliable construction which enables wheelchair users to get up-and-down and in-and-out of vehicles such as vans or similar types of vehicles without the need for leaving the wheelchair. The drive system for the lift apparatus is completely electric and operates the lift apparatus up and down at a smooth, safe speed and can be stopped at any position via finger-tip control accessible to the user on the frame structure. At ground level the user simply wheels off the platform or ramp, actuates a switch which then automatically returns the carriage lift assembly to its original position inside the van. The lift apparatus of the present invention allows one to use a normal vehicle parking space. Accordingly, there is no longer the problem of the user being trapped outside the van by reason of another car being parked in the next space. In this regard, the lift apparatus sits completely inside the van and utilizes a minimum amount of interior van space. In the invention, the lift apparatus requires no major modification to the vehicle. It can be installed, removed, and re-installed in another van, as desired. Significantly, the lift apparatus is completely electric. Accordingly, there are no hydraulic cylinders requiring endless maintenance, no hydraulic cylinders to malfunction in the wintertime, and no messy oil leaks to clean up. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a generally perspective view illustrating the rotary wheel chair lift apparatus of the invention installed in the side-door opening of a vehicle, such as a van; FIG. 2 is a fragmentary side elevation view, on an enlarged scale, illustrating the upper portion of the support column and carriage lift assembly of the invention; FIG. 3 is a fragmentary, side elevation view, partly in section, illustrating the lift apparatus of the invention; FIG. 4 is a fragmentary, section view, on a large scale, taken along the line 4--4 of FIG. 2; FIG. 5 is a fragmentary top plan view, on a large scale, looking down on the carriage lift and drive assemblies illustrated in FIG. 3; FIG. 6 is a fragmentary top plan view looking down on the motor and gear drive mechanism for rotating the support column about a vertical axis as illustrated in FIG. 3; FIG. 7 is a fragmentary vertical section view taken along the line 7--7 of FIG. 8; and FIG. 8 is a fragmentary, top plan view looking down on the lift platform illustrated in FIG. 3. DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring now again to the drawings and specifically to FIG. 1 thereof, there is illustrated the wheelchair lift apparatus, designated generally at 1, of the present invention. As shown, the apparatus 1 is installed for use with a conventional vehicle V, such as a recreational van or the like. As shown, the lift apparatus 1 is disposed within the side-door opening D of the vehicle adapted for rotational movement about a generally vertical axis, as shown by the arrows, at 4. Accordingly, the lift apparatus is adapted to swing inwardly and outwardly within the opening D of the van to provide ingress and egress to the user, such as an invalid. Specifically, this pivotal movement about the vertical axis, as at 4, is illustrated in FIG. 6 which illustrates the lower drive mechanism, designated generally at 19, for the lift apparatus 1. As best seen in FIG. 3, the lift apparatus 1 is mounted on the floor F of the vehicle chassis C. More specifically, the lift apparatus 1 includes a carriage assembly, designated generally at 8, which is mounted on the floor F of the chassis C as aforesaid. In the form shown, the carriage assembly 8 includes a column support mechanism 10 which comprises a vertically disposed column member 12 (FIG. 3) which is mounted on a base plate 14 (FIGS. 3 and 6) which, in turn, is mounted on the floor F of the chassis. As shown, the lower end of the column 12 is fixly attached to a driven segment gear 16 for rotation about a vertical axis. Specifically, it will be seen that the base plate 14 is disposed in the same general plane as the surface of the floor F chassis. The segment gear 16 is disposed in vertically spaced relation above the base plate 14 and is fixably attached, as at 18, to the column 12 (FIG. 6) as to rotate the column 12 vertically about its axis upon activation of a motor drive mechanism, designated generally at 20. The segment gear 16 is driven by a drive gear 13 (FIG. 3) via a drive gear 15 actuated by drive motor 20, as seen in FIG. 6. Preferably, the segment gear 16 is of a generally 90° configuration so as to impart a corresponding full 90° rotation of the column 12 about its vertical axis and so as to correspondingly rotate the lift apparatus 1 through 90° inwardly and outwardly of the door opening D. In operation, as best seen in FIG. 6, the segment gear is shown in solid line so that the lift apparatus 1 is swung outwardly completely 90° to its full open position. As shown, this would be at right angles in respect to the door opening D whereas, the illustration in perspective view of FIG. 1 illustrates the lift apparatus 1 disposed generally at approximately 45°. In FIG. 6, the lift apparatus 1 is in the full open or 90° position to receive the user. In this position, an inclined cam surface 22 (FIG. 6) activates the limit switch 24 (FIG. 6) which de-activates the motor 20 to enable the user to lower the lift apparatus 1 vertically to the ground position, as seen in dotted line at G in FIG. 3. In the reverse operation, the lift apparatus 1 is raised vertically upon actuation of the motor 20 via lever L, which raises the lift apparatus 1 vertically, as illustrated by the arrow 26 to the solid line position illustrated in FIG. 3. The user then actuates another lever L2 so as to pivot the lift apparatus 1 inwardly about a generally horizontal plane upon rotational movement of the column 12 about its vertical axis. This rotational movement brings the segment gear 16 through a rotation of approximately 90° so as to engage another limit switch 28 (FIG. 6) which then again deactivates the motor 20 which seats the lift apparatus carrying the user in grounding engagement with the floor F of the chassis of the vehicle, as illustrated in broken line in FIG. 3. In the form shown, the control includes the lever L, which activates the control circuit (not shown) for raising the lift apparatus 1 vertically, as illustrated by the arrow 26 in FIG. 3. The lever L2 actuates the control circuit (not shown) for rotating the lift apparatus 1 into and out of the van about a generally horizontal plane. In accordance with the invention, the column assembly 10 includes the column member 12 which, as illustrated in cross-section at FIG. 4, is of a polygonal, such as square-cross-sectional configuration. Specifically, the column 12 has four generally planar sides, as at 30, connected by generally flat edge portions, as at 32. In the invention, it is to be understood that the surfaces 32 could be other than flat so as to include some degree of radius, as desired. Preferably, the column 12 includes an interior strengthening plate 34 which preferably extends transversely between the flats, as at 32. Preferably, the plate 34 may extend throughout the full vertical length of the column 12 or less than such length, as desired. Now in the invention, there is employed a plurality of bearing members, designated generally at 38, for friction rolling engagement on the column member 12. Preferably, the roller bearing arrangement is structured and arranged so as to provide relief areas, as at 40, to enable full surface-to-surface engagement between the confronting surface, as at 40, of the column 12 (FIG. 4) with the corresponding confronting surface, as at 42, of the respective rollers 44 and 46. In the form shown in FIG. 3, the rollers 44 are mounted upwardly on a roller housing assembly 48 and the rollers 46 are mounted downwardly of the assembly 48, as best seen in FIG. 2. It will be seen that the upper rollers 44 include two individual generally frusto-conical rollers 45 and the lower rollers 46 include two individual generally frusto-conical rollers 45 and the lower rollers 46 include two individual generally frusto-conical rollers 47 which engage, by rolling, the column 12, as best seen in FIG. 4. As best seen in FIG. 4, the roller assembly 38 incorporates with each of the four (4) wheels 45 and 47 an adjustment device, designated generally at 50, which are of identical construction. Each adjustment device 50 includes a mounting block 52 fixably attached to the roller assembly 48. An adjustment screw 54 (FIG. 4) is threadably connected to an axle 56 which rotatably mounts the respective rollers 45 and 47 of the respective roller assemblies. The axle 56 is provided at its opposite ends with bearing surfaces, as at 58, which are disposed for sliding movement within slots, as at 60, provided in the mounting blocks 52 for limiting axle adjusting movement of the screw within the block 52. Preferably, the screws are axially adjustable via fasteners, such as nuts 64, so as to provide selective adjustment of the rollers 45 and 47. This adjustment enables full surface-to-surface engagement at a generally 45° orientation of the respective rollers 45 and 47 with the confronting planar surfaces 30 of the column 12. Preferably, each of the wheels 45 and 47 is provided with an internal anti-friction bearing mechanism, designated generally at 70. Each of the mechanisms 70 include a bearing member which is commercially available. This bearing member is press-fit within the respective rollers 45 and 47 and maintained against axial movement by a retainer ring 74. As best seen in FIGS. 2, 3 and 5, the lift apparatus 1 includes an upper drive assembly, designated generally at 80, for moving the lift apparatus 1 horizontally on the column assembly 10. As shown, this upper drive assembly 80 includes a drive motor 82 fixably mounted on a top support plate 84 which is fixably attached to the upper end of the column 12. The drive motor 82 (FIG. 3) is operably connected to a drive screw 86 via a pair of drive pulleys 88 and 90 (FIG. 5) connected by two (2) belts 87 and 89 to the input drive end 92 (FIG. 3) of the drive screw. The drive screw 86 is mounted at one end to a bracket 98 which is fixably attached to the roller assembly 48. The lower end of the drive screw 86 is mounted for rotation within a bearing, as at 100, which, in turn, is attached to a bracket member 102 (FIG. 3) fixably attached to the segment gear 16. Preferably, the bearing 100 is of a plastic, such as Teflon material, or the like. As best seen in FIG. 3, the bracket 98 is illustrated in solid line when the lift apparatus is in the full vertically oriented "up" position and in dotted line in the full vertically oriented "down" position. In the invention, the lift apparatus 1 comprising the carriage assembly 8 includes a frame structure, designated generally at 101, which is of a generally inverted U-shaped configuration as best illustrated in FIG. 3. More specifically, the structure 101 includes a generally planar ramp or platform 102 which is carried by a pair of oppositely disposed side columns 104 and 106 which are interconnected at their top ends by a cross member 108. As shown, the outerward support column 106 is inclined to provide an offset portion as at 110 to provide sufficient clearance for the wheelchair user. The members 108 and 106 are interconnected by a strengthening gusset, as at 112, to provide rigidity between the component parts. Similarly, the parts 104 and 108 are provided with another gusset, as at 114, for the same purpose. As shown the inner column 104 is provided with a brace member 116 which is fixably attached at its lower end to the platform 102. As best illustrated in FIG. 3, the cross member 108 is provided at its inner end with a control box, designated generally at 118, which mounts the controls L1 and L2, as aforesaid. As best seen in FIG. 7, the platform 102 is provided with a pair of oppositely disposed strengthening side plates 122 which are made integral with and are disposed in generally vertically upstanding relation in respect to the platform 102. As shown, the inner side plate 120 (FIG. 7) is fixably connected, as by weldments, to the inner column member 104 and to the brace member 116. Also, the side plate member 120 includes an integral flange 124 which provides a support for a freely rotatable pulley 186, as will be hereinafter more fully described. As shown, the other outer side plate 122 (FIG. 3) includes a further gusset, as at 126, for strengthening the inner connection between the side plate member 122 and the outer column member 106. It will be seen, therefore, that the frame structure defined by the columns and cross members 104, 106 and 108 define a generally inverted U-shaped configuration which is disposed substantially in the same general vertical plane with the support column member 12 which mounts the roller housing assembly 48. Similarly, the drive screw 86 is disposed in a generally vertical parallel relationship in respect to the support column 12, as best illustrated in FIGS. 2 and 3. In the invention, this parallel relationship between the component parts is achieved by a mounting bracket, as at 130, which is fixably attached at one end, as at 132 to the distal end of the support column 12 (FIGS. 1 and 5) and at the other end via a flange 134 secured, such as by screws and the like, to the column 136 of the vehicle. This bracket provides a structural support for maintaining the parallel relationship between the parts and the perpendicular relationship of these parts in respect to the floor F of the vehicle chassis. As best illustrated in FIGS. 7 and 8, the platform 102 of the frame structure 8 includes a forward stop mechanism, designated generally at 140, disposed for horizontal reciprocal movement on the platform member 102. More specifically, this mechanism includes a support plate 142 which has an upturned end, as at 144, adapted to prevent forward rolling movement of the wheelchair when installed thereon. The support plate 142 includes a pair of oppositely disposed integral flanges 146 and 148 of generally inverted L-shaped configuration. Each of the flanges mounts a pair of rollers 150 and 152 adapted for rolling engagement within correspondingly shaped U-shaped channel members 154 and 156 fixably attached to the platform 102. The guide channels 154 and 156 each include a pair of stop elements 160, which serve to limit and provide a stop for the rollers and hence, forward movement of the mechanism 140 as illustrated by the arrow 162 in FIGS. 7 and 8. More specifically, the stopping movement occurs when the rollers 152 are brought into abutment with the stops 160. The opposite end of the guide members 154 and 156 are provided with elastomeric stop members (rubber) 164 which served to provide a cushion upon resilient retracting movement of the mechanism 140. The retracting movement of the mechanism is automatically accomplished by a pair of oppositely disposed extension spring elements 166 which are attached at one end, as at 168, to flanges 169 on the respective guide members 154 and 156 and at the other end to the side flanges 146 and 148, as best seen in FIG. 8. By this arrangement, the forward stop mechanism 140 is disposed for reciprocal movement in a generally horizontal plane parallel to the general plane of the platform 102 so as to enable the wheels (not shown) of the wheelchair to engage the stop 144 so as to drive the assembly forward throughout its full through (dotted line FIG. 7) so that the rearwardmost ends of the flanges 146 and 148 are disposed generally at the center-line, as at 171, of the oppositely disposed column member 104 and 106. In this position, it has been determined that the wheels of the wheelchair can be supported by and transferred forwardly to a point sufficient such that the center of gravity, i.e. the load, of the wheelchair user including the wheelchair, is disposed slightly forward of the generally vertical plane defined by the generally inverted U-shaped structure 102 of the frame. Preferably, this load distribution is disposed at such center line or forward of the same so as to prevent accidental rolling movement of the wheelchair rearwardly and off of the lift platform during normal use thereof. As best seen in FIG. 7 a rear stop mechanism, designated generally at 170, is provided to prevent inadvertent rearward rolling movement of the wheelchair off of the platform 102. As shown, the mechanism includes a rear stop plate member 172 which is pivotably attached to the platform 102 via an elongated piano-type hinge spring 174 which is fixably attached, as by weldments, to the platform 102 and the stop 172. As best seen in FIG. 7, this spring hinge biases the stop plate 172 forwardly or in a counter-clockwise direction, as illustrated by the arrow 176. The stop plate 172 is actuated by means of the cable 178 which is fixably attached by a turn buckle, as at 180, and then threaded through a guide roller 182 and then around a guide roller 186 fixably mounted on the flange 124. At this juncture, the cable takes a 90° turn and extends vertically upwardly generally parallel to the inner column member 104 and attached at its free end to a pivotal link 188. The link 188 is pivotally attached at one end, as at 190, (FIG. 2) to a cross member 192 which is integrally connected between the roller assembly 148 and the inner column member 104. As shown, the free end of the cable 178 is attached, as at 194, adjacent the free end of the cable 178 is attached, as at 194, adjacent the free end of the pivot link 188. As best seen in FIG. 3, another cable member 196 is fixably attached, as at 198, to the pivot link 188 generally intermediate its ends. The cable 196 is fixably attached at its other end, as at 202, to a ball screw assembly 204 which receives the drive screw 86 for raising and lowering the carriage lift assembly 48 in a generally vertical direction. The operation of stop mechanism 170 can be illustrated with reference to FIGS. 3 and 7. As shown, in the full-up or solid line position illustrated in FIG. 3, the pivot link 188 is disposed in a generally 45° orientation. In this condition, the upper cable 196 is held in a taut condition by means of the upward force exerted by the ball screw assembly 204, whereas, the lower cable 178 is only under sufficient tension so as to maintain the stop member 172 in the upward position, as illustrated in FIG. 7, so as to override the biasing force of the piano spring hinge 174 thereby to hold the stop member 172 in a generally 45° opientation in relation to the platform 102. Upon actuation of the outer lever L1 the carriage lift assembly 8 is vertically lowered with the cables 196 and 178 maintained in a relatively constant load condition until platform 102 bottoms out with the ground. After grounding, continued actuation of the outer lever L1 acts to overdrive the upper drive motor 82 which, in turn, drives roller drive screw 204 downwardly. This movement causes the upper cable 196 to slack and the lower cable 178 to become under tension due to the resilient biasing of the piano spring hinge 174. This causes pivotal movement of the pivot link 188 in a generally clockwise direction (FIG. 2) which enables the stop plate member 172 to pivot downwardly, as shown by the arrow 176 (FIG. 7) into the general plane of the platform member 102. In this position, a limit switch 210 mounted on the cross member 192 is contacted which stops further vertical downward movement of the ball screw 204. In the invention, the cable 178 has a 2000 p.s.i. at test capability and the stop plate 172 has a 1600 p.s.i. force capability. The lift platform 102 has a lifting capacity of 960 pounds and a stationary load capacity of 2000 pounds. The upper motor 82 has a 3000 r.p.m. and draws 28 amps at a 400 lbs. loading capacity on the platform. In the invention, there is at least a 2 to 1 safety factor in respect to the V.A. recommended lift capacity at 400 lbs. In a technical operation, with the user then positioned on the platform 102, he merely actuates the switch lever L1 which actuates motor 82 via cables 88 and 90 to rotate the screw 86 in the stationary ball screw 204 which is fixably attached to the support column 12. This raises the platform 102 to the desired height, as illustrated in solid line in FIG. 3, whereupon the lift will stop automatically upon actuation of a suitable limit switch (not shown) being utilized to automatically de-energize the motor 82. At this position, the user then actuates the other control lever L2 which activates drive motor 20 (FIG. 6) so as to rotate the lift to the door D into the van. He then again actuates control L1 so as to automatically lower the lift and platform 102 to the floor F of the van. Automatic operation of the forward stop mechanism 140 and the rear stop mechanism 170 operate during this sequence of this steps, as aforesaid. Accordingly, reversal of the above steps enables the user to readily discharge himself from the van once again to ground level, all accomplished automatically under his own control in accordance with the advantages of the present invention.

4y

SUMMARY [0001] The invention is a method that, by processing captured images by means of a submarine camera ( 10 ) located inside a fish breeding cage ( 11 ) and under the mass of fish or feeding zone ( 12 ), allow to detect and quantify in real-time the non consumed particles of food ( 13 ). The submarine camera ( 10 ) captures images that are sent ( 14 ) ( 15 ) to a computer ( 16 ), which, by means of a software, digitalizes and quantifies the particles in real-time, making alarms or actions when the number of particles reaches established patterns. DESCRIPTION [0002] One of the problems that characterizes the aquaculture is that the animals and plants involved in the farm are under the water, and the most of them can not be observed, unless by using special equipment and instrumentation. [0003] In the case of the fish aquaculture, it is very difficult to verify in a visual and permanent way the amount of food that is consumed. The impossibility to verify the consumption in real-time originates two main problems: 1) the economic lost because of the food that is not consumed; and 2) the negative environmental impact that produces the wasted food. [0004] The portion of food given to the fish is calculated in a theoretic way considering physical-chemistry parameters (temperature of water, amount of oxygen in the water, etc.), and biological parameters (age and size, etc.). In this calculation there are not considered other factors that may affect in a direct way the level of consumption of food by fish. For example, the stress caused by any activity related to the fish farm management may provoke that fish stop consuming food for many days. Another factor may be the time when fish get satisfied and stop consuming food. Both factors may be determined only by observation in real-time. Fish consume the food as long as it is dropped into the respective fish breeding cage, and in this process the fish must eat the pellets as long as they go downward through the water. The pellet that is not consumed, reach the bottom of the breeding cage and the environment and obviously became lost. [0005] As a way of example, in the salmon farm related with the industrial scale, the food costs represents about the 60% of the total production costs. Therefore, the optimization in the use of the food may influence significantly the economic result of the company. [0006] The invention introduced, comprises a system and a submarine camera located inside the cage under the big mass of fish arranged during the breeding process, providing a mean for observing the process of feeding and behavior of fish in real-time, in order to make the necessary changes in the proper time. [0007] On the other hand, the invention provides a good mean for minimizing the negative environmental impact caused by the excess of food provided to the fish. [0008] Besides, it can be used for controlling predators or other problems in the fish behavior. Even more, the invention is able to be used in any kind of fish farm in breeding raft-cages in which there is used mobile or static automatic or manual feeders, for feeding salmon, trout, croaker, sturgeon, carp, hake, sea bass, sea bream, tuna, eel and others. [0009] Currently, in the prior art, in a PCT searching, under IPC classifications A01K 61/02 and G01N 023/223 there are described some methods for monitoring by means of acoustic sounding, based on the Doppler effect in order to detect the particles of food inside a determined perimeter, which uses sensors arranged inside and outside the raft-cage in which the fish are kept. The inconvenient of these systems is their low reliability in the interpretation of the acoustic sensor, because it may not discriminate another element from a food particle, and may present mistakes in their statistics because it quantify all the interferences inside its sweeping area. [0010] PORO AB. uses a submarine camera for verifying the behavior and feeding of fish, focusing downward and using illumination systems in order to be able to observe the particles of food. The major inconvenient is that fish may be negatively affected by the illumination system. [0011] Norcan Electrical Systems Inc. uses a submarine camera connected by a serial connection to a central feeding system. An operator is visually monitoring each raft-cage from a base station, making the necessary adjustments to the feeding system. A disadvantage in this case is that all the rafts are connected to the system, therefore the operator must verify one by one each raft-cage which makes difficult to activate properly and in the right time the feeding system. [0012] In the prior art there is not disclosed any system able to capture images and quantifying in real-time the non consumed food particles, by means of a images processing system, which uses a submarine camera located under the mass of fish and that stops immediately the feeding of fish or decreases the related feeding rate when the assigned limit is exceeded. DESCRIPTION OF THE INVENTION [0013] In FIG. 1 it is shown a submarine camera ( 10 ) located inside a fish breeding raft-cage ( 11 ) of any demersal species (i.e., the ones that swim and eat in the column of water) The submarine camera ( 10 ) must be located under the group of fish formed in the feeding zone ( 12 ) during the feeding process. Depending on the specie of fish, a skilled fish farmer will determine easily the best location for the submarine camera ( 10 ), generally near the center of the cage and between 4 and 12 meters depth. [0014] The food is supplied in the top of the cage, and the fish ( 12 ) consume it as long as it gets inside the raft-cage ( 11 ) in which they are kept. The particles of food sink slowly through the column of water, therefore the images of the particles of non consumed food ( 13 ) may be easily captured by the submarine camera ( 10 ). [0015] The submarine camera ( 10 ) may be any model able to satisfy the NTSC or PAL signal requirements, preferably one of the models Equa VISION, arranged preferably focusing upward or in the best possible arrangement for a better vision. In order to take the signal from the submarine camera ( 10 ) to the computer ( 16 ), it is used a wire connected to a conventional transmitter ( 14 ), located in the upper part of the raft-cage. This transmitter ( 14 ) transmits a signal to a conventional receiver ( 15 ), where the signal is received and sent to the computer ( 16 ) by means of a wire. A transmitter equipment that meets perfectly well the requirements is the module TRUP VISION. [0016] The obtained signal of the submarine camera ( 10 ), is given to the system, by means of a image processing software, preferably the HALCON of MVTec GmbH, which controls the image acquisition card (frame grabber). A proper card according to the requirements of the present invention is one of the Falcon Family of IDS Imaging GmbH. [0017] The food particles have a shape and texture relatively clear. By mathematical algorithms commonly used for determining shape and texture, the software discriminates the images of particles having certain characteristics respect to a predefined pattern. [0018] The software programming characteristics are the following: [0019] The imaging processing software takes an image and makes a grey scale spectrum analysis. By means of an algorithm of shape and texture there are determined all those shapes representing a food particle. Methods like this are well known for any skilled person in that technical field. Then, the captured image is analyzed is analyzed by the software by algorithms that determine, in real-time, the amount of particles of food that are passing through the feeding zone or that were not consumed by fish. [0020] The system may display information in a graphic way, in a screen and may be integrated by an electronic interface with duplex communication, with the automatic feeding control software. It may export the information by internet and/or magnetic means, as well as it makes possible the data acquisition. [0021] A skilled person in this area would know how to make a recognizing algorithm like the one mentioned above and the related equations in order to develop the software that provides the information in real-time of the number of particles over the predetermined limit values. For the same reason, the invention must not be limited by the specific algorithms used. On the contrary, the scope of the invention is to be limited only by the following claims.

4y

[0001] This is a Continuation-in-Part application of Ser. No. 11/699,151, filed on Jan. 29, 2007, which is herein incorporated by reference in its entirety. BACKGROUND OF THE INVENTION [0002] (1) Field of the Invention [0003] The invention relates to the treatment of wastewater and more particularly, to a septic system design with true siphon dosing and effluent filtration with backwash. [0004] (2) Background of the Invention and Description of Previous Art [0005] It is common knowledge among sanitary engineers that to prolong the life of septic fields it is necessary to clean or filter the effluent from the septic tank and to rapidly discharge a measured quantity (dose) of filtered effluent to flood the septic fields. The dose volume is normally about 70% of the septic field volume. This procedure extends the life of the septic field by distributing the effluent, and more importantly, the residual solids contained in the effluent, over the entire field rather than only near the entrance to the field where they will accumulate and eventually clog the first few feet of the septic field thus rendering a portion of the field's capacity to percolate effluent useless. Once this deterioration starts it will overload the remaining functioning portion of the field, which will lead to a total failure of the field in due time. The replacement of a failed septic system is very costly and messy operation. [0006] Before describing the prior state of the art in this field it would be useful to keep in mind that septic tanks are buried underground to prevent freezing or for esthetic reasons. There is, in general, six inches to a foot or two of earth on top of the tank. To remove the tank covers for pumping out the tank contents or to inspect for malfunctioning components of the system, earth over the tank covers must be dug out to gain access. Access to the septic tank is not easy and is generally beyond the aptitude of most building owners. Typically a functioning septic tank should be pumped out once every two or three years. [0007] The following patents were examined to ascertain the prior state of the art in this field. [0000] Hanford, William E., U.S. Pat. No. 4,040,962 Ball, Harold L., U.S. Pat. No. 4,439,323 Gavin, Norman, U.S. Pat. No. 4,838,731 Daniels, Byron C., U.S. Pat. No. 5,198,113 Graves, Jan D., U.S. Pat. No. 5,207,896 Richard, James G., U.S. Pat. No. 5,290,434 Ball, Eric S., U.S. Pat. No. 5,492,635 Stuth, William L., U.S. Pat. No. 5,690,824 Wilkins, Charles A., U.S. Pat. No. 6,231,764 [0008] Methods and apparatus for improving the performance of septic system as described in the above mentioned patents have found limited use due to one or more of the following drawbacks. 1. High initial investment. 2. Cannot be retrofitted in existing installations. 3. Costly maintenance and operation. 4. Complexity and bulk. 5. High elevation differential requirements. 6. Not true siphons. 7. No dosing provision. 8. Insufficient or no filtration. 9. No provision to indicate the need for backwash or filter replacement. 10. Need for external power (electric pumps). 11. Need for frequent refill of chemicals. 12. Not intended for Septic Systems. [0021] It is important to recognize the enormity of the job a residential septic system must perform over its intended life time which is typically between 20 or more years. A typical single family consumes approximately 1000 gallons of water every day. Over a 25 year period the septic system processes over 9 million gallons or 76 million pounds of effluent. The quality of domestic waste dumped into the septic system varies greatly with the lifestyle of each family, particularly if a food disposal unit is utilized to grind kitchen waste and send it to the septic tank. The amount of sludge and flotsam removed by frequent tank pump outs will also vary over a wide range. [0022] The suspended solids are of most concern because they clog up the septic fields. Daniels, '113 utilizes open cell polymeric foam to filter the effluent from the septic tank. No information is provided regarding the particle size of the solids, which will pass through the filter medium. However it is easy to guess from the general description that the particle size will be fairly small. Although the filter will remove most of the suspended solids from the effluent, frequent replacement of the filter element is necessary. This requires shoveling away the earth to expose the cover, removing the cover and replacing the filter, replacing the cover and the earth, not a welcome task with the ground frozen solid in winter. The reference also requires an electric pump to move the filtered effluent from the dosing chamber to the septic septic fields, thereby requiring the provision of electric service at the tank. [0023] Ball, '635 describes a series of multiple size filters the smallest of which has an opening of ⅛ th of an inch. Here too an electric pump is required, and has no backwash system. A ⅛ th of an inch opening in the filter will pass 3,175-micron particles. Graves, '896 describes a multistage filtration process, which aims to filter particles as small as 1000 microns. However this process is dependent upon chlorination, aerobic agitation, and optional de-chlorination, thus requiring electrical power and chemicals. When the filters clog, the unit must be removed and cleaned. As with the previous reference this requires exposing and opening the tank to clean or replace the filter, again a substantial undertaking. No dosing mechanism is provided so, with the exception of the filter, the septic system has the site limitations of a simple gravity fed system. [0024] Filtration systems are generally categorized by the particle size, which will pass through them. Particle size is generally measured in microns. A Micron is one millionth of a meter or 40 millionth of an inch. For reference the high quality drinking water filters block particles larger than 5 microns from passing through them. Some coarse drinking water filters would pass 30 micron particles. With respect to filtration in a septic system, to pass solids of over 3,000 microns is tantamount to no filtration at all. A great majority of suspended particles in a septic tank are much smaller; therefore much finer filter media are necessary to clean the effluent significantly. It becomes clear why Ball, '635 cites that the filter requires cleaning only as often as the container (the septic tank) requires pumping to remove accumulated sludge. [0025] It is difficult to establish the suspended particle size distribution of the effluent, because each family's life style is different. Assuming a linear distribution of particle size the following table will illustrate the importance of filtration medium. [0000] TABLE I Quantity of suspended solids in 76 million lbs (38,000 Tons) of effluent processed over a lifetime of 25 years. Percent (by Weight) Quantity 1.0% (10,000 ppm.) 380 Tons 0.1%  (1,000 ppm.)  38 Tons 0.001%    (100 ppm.)  3.8 Tons 0.0001%      (10 ppm.) 760 lbs. [0026] Even at the lower concentrations there is sufficient quantity and volume of suspended solids, which if not removed by filtration would plug up any septic field. Clearly, the importance of good effluent filtration cannot be overemphasized. [0027] By comparison this invention filters particles as small as 100 to 200 microns by using a super fine filter. A 100 mesh screen (10,000 holes per square inch) will filter 180 micron or larger particles and a 150 mesh screen (22,500 holes per square inch) which will filter 100 micron or larger particles, and the effluent will be almost as clean with respect to suspended particles as the domestic water supply, a great benefit for the life of the septic field. [0028] The present invention shows the use of a precision and true siphon to dose and filter the liquid extracted from the central clear zone of a septic tank. The unit is contained in a housing mounted and ported on the discharge side of a septic tank. Liquid flows into the housing from the bottom thereof, passes through a fine mesh basket strainer or filter, and rises in the housing until enough is collected to start the siphon. Then the siphon is initiated through the lifting of a float and the proper dose is delivered to a distribution box. After delivery of the dose volume the siphon is broken, and a predetermined short time thereafter a remote timer triggers a solenoid valve, which sends pressurized domestic water to backwash the filter for a predetermined time after which the system becomes ready for the next dosing cycle. [0029] Referring now to FIG. 11 , there is shown a typical septic system 120 comprising a septic tank 122 , a drainpipe 124 , and a distribution box 126 . The inflow 127 to the septic system 120 is delivered through a pipe 121 emanating from a building or house (not shown) and received at the inlet of the septic tank 122 . A septic field towards which the outflow 128 from the distribution box 126 is directed is not shown. [0030] The total elevation difference 130 is defined as the difference in elevation between the bottom of the inlet pipe 121 and the bottom of the lowest level in the distribution box 126 . The total elevation difference 130 can be further broken down to the sum of the septic tank drop 132 , the pitch drop 134 , and the distribution box drop 136 . [0031] The selection of an effluent delivery system i.e. a gravity siphon, or a pump system depends on the total elevation difference 130 . In most health jurisdictions the minimum required difference 132 between the inlet and outlet of the septic tank is about three inches, but in some cases it can be as much as six inches or more. The pitch drop 134 depends upon the distance 135 between the septic tank and the distribution box. Most health departments require that a pitch or gradient of 1 in 100 or about ⅛ of an inch per foot of drainpipe length be maintained. The distribution box drop 136 is normally about one inch. The pitch drop 134 dictates the choice of an effluent disposal system as follows: a. If the pitch drop 134 is insufficient to maintain the required pitch or if the distribution box is at a higher elevation than the liquid level in the septic tank, then it becomes necessary to install a pumping system. b. If the pitch drop 134 is just enough to maintain a pitch of 1 in 100, then a simple gravity system is the only choice. c. If the pitch drop 134 is large enough to meet the incremental elevation differential requirements, then a classical Bell Siphon (not shown) or the so-called siphon systems (some of which are included in the list of patents cited i.e. Ball, '323 and Richard, '434) on the market can be used. [0035] Referring to FIG. 12 , these systems 140 require a dosing chamber 148 downstream of the septic tank 142 , which holds the entire dose volume. Depending upon the dose volume, which governs the dimensions of the dosing chamber 148 , the incremental siphon drop 147 can be anywhere from 6 to 18 inches on top of the pitch and distribution box drop 149 . The pitch drop here is measured from the input to the drainpipe 144 near the bottom of dosing chamber 148 . The dose volume is denoted in the figure by 146 . The septic tank drop 143 is measured between the bottoms of the entry and exit pipes of the tank 142 , and plays no role in the performance of the above mentioned so called siphon systems. [0036] Neither, Ball, '323 nor Richard, '434 are true siphons, because the effluent is always under a positive hydrostatic head, and there is no vacuum anywhere in the drainpipe. A true siphon is defined as a continuous tube (siphon tube) that allows liquid to drain, without requiring pumping assistance, from a reservoir at a higher elevation to a point at a lower elevation, where the tube passes through an intermediate point that is higher than the reservoir. The up flow from the reservoir is driven by the pressure difference created by the vacuum formed by the siphon process at the highest point of the siphon tube. SUMMARY OF THE INVENTION [0037] It is an object of this invention to provide an economical and reliable true siphon operated dosing system to prolong the life of septic fields of residential dwellings or commercial buildings. [0038] It is yet another object of this invention to provide an economical and reliable true siphon operated dosing system that can be deployed in cases where the pitch drop is insufficient even for a simple gravity system. [0039] It is still another object of this invention to provide an economical and reliable true siphon operated dosing system that utilizes the septic tank drop to provide additional hydrostatic head to increase the flow rate of the siphon. [0040] It is another object of this invention to provide an economical and reliable true siphon operated dosing system that utilizes the full difference in elevation to drive the siphon flow at a high velocity. [0041] It is yet another object of this invention to provide an economical and reliable true siphon operated dosing system that utilizes a float-operated valve to initially block the flow of screened effluent into the drainpipe. [0042] It is still another object of this invention to provide an economical and reliable true siphon operated dosing system that passes the effluent through a fine mesh screen filter prior to its entry into the working section of the siphon. [0043] It is still another object of this invention to provide an economical and reliable true siphon operated dosing system that backwashes the fine mesh filter screen after each dosing cycle. [0044] These objects are accomplished by a precision siphoning unit containing two cylindrical control floats arranged respectively above and below, and concentric with a stationary cylindrical member having large central flow passages surrounded by a plurality of smaller flow passages. An elastic sealing surface on the underside of the upper float provides a seal across inner and outer valve seats on top of the cylindrical stationary member thereby blocking flow through the large flow passages. An elastic sealing surface on top of the lower float seals the plurality of smaller flow passages protruding out of the bottom of the stationary member. The floats and the stationary member are housed in a cylindrical barrel having a top cover, an open bottom, and a side opening. The stationary member is sealed to the inside of the barrel. A fine mesh screen basket filter of a diameter, slightly larger than that of the barrel is supported in a wire mesh basket, which in turn is fastened to the bottom of the barrel. A central pipe passes through the barrel, the floats, and the stationary member. A rotatable sprinkler arm is attached to the bottom of the central pipe with a rotatable seal. The sprinkler arm fits inside the basket filter. The barrel assembly with the basket filter and sprinkler are contained in a larger diameter cylindrical outer housing with a top cover. A water pipe passes through the top covers of the barrel and the outer housing, and is connected, through a solenoid valve, to a pressurized domestic water supply in the house or building, which is served by the septic system. The water pipe enters the central pipe concentrically and terminates therein. The outer cylindrical housing is mounted on the discharge side of the septic tank service the house or building. [0045] Effluent from the clear zone of the septic tank passes through an inlet pipe into the bottom of the outer cylindrical housing, where it first passes through the basket filter. As the liquid level rises in the septic tank due to incoming waste, the now filtered effluent is blocked from passing through to the discharge port of the precision siphon unit by cooperation of the floats and the stationary member. When the liquid rises above the end of the inner water pipe, the air pressure therein begins to rise. The liquid continues to rise in the housing and in the central pipe, building up head, until it passes through spillover ports at the top of the annulus between inner and outer central pipes. The spilled over liquid falls into the compartment surrounding the upper float. The float then becomes buoyant, rises, and releases a sudden surge of flow through the central flow passages. The flow passes through the exit port of the barrel taking along with it most of the air in the upper float compartment, and the drainpipe. [0046] Just prior to the upper float becoming buoyant a pressure switch, located in the building and connected to the water pipe, senses the increase in air pressure in the water pipe. At a preset pressure, the pressure switch triggers a timer which, after a time delay, initiates the opening of a solenoid valve in the building which sends a flow of high pressure domestic water through the water pipe for a short time period (about one minute). This sudden rush of high-pressure water pushes the remaining air out of the siphon unit, the drainpipe, and the system, now primed, initiates the siphon flow. The flow of liquid continues at a gradually diminishing rate as the liquid level in the tank drops. When the liquid level between the barrel and the outer housing falls below vent openings in the barrel, which are located below the level of the floats, air enters the barrel, the floats drop, and the siphon is broken. [0047] After a time delay to assure that the siphon flow has ceased, the timer in the building or house again opens the solenoid valve for about five minutes to send a second flow of pressurized domestic water through the central pipe causing the sprinkler in the siphon unit to back flush the fine mesh basket screen filter, thereby driving the accumulated particulate matter on the filter screen back into the septic tank. [0048] It is yet another object of this invention to provide a method for retrofitting the precision siphon unit of this invention into an existing conventional gravity septic system without removing any of the components of the original system. [0049] This object is accomplished by lowering the exit port of the existing septic tank by creating a new exit port and plugging the old port, placing a new smaller diameter flexible drainpipe into the existing drainpipe, and fitting a new discharge pan into the existing distribution box. [0050] It is another object of this invention to provide an economical and reliable true siphon operated dosing system to prolong the life of septic fields of residential dwellings or commercial buildings wherein backwashing of said fine mesh filter is accomplished without a water supply connection of the dosing unit to the building being serviced thereby eliminating the need for a control box in the building. [0051] This object is accomplished by backwashing the fine mesh filter with the volume of liquid trapped in the dosing unit after the siphon is broken. BRIEF DESCRIPTION OF THE DRAWINGS [0052] FIG. 1 shows a cross section of a modern two-compartment septic tank with the precision siphon unit of the present invention attached on the outside and downstream of the septic tank. [0053] FIG. 2 shows a cross section of the precision siphon-dosing unit taught by this invention. [0054] FIG. 3 is an isometric view of the core floats and spray assembly of the precision siphon unit taught by this invention. [0055] FIG. 4 is a top view of the lower float of the float and spray assembly of this invention. [0056] FIG. 5 a is a top view of the stationary central unit of the float and spray assembly of the invention. [0057] FIG. 5 b is a top view of the upper float of the float and spray assembly of the invention. [0058] FIG. 6 is a block diagram showing the layout of the interface between the building or house and the precision siphon-dosing system (installed on the outside of the septic tank) of this invention. [0059] FIGS. 7 a and 7 b are a cross sectional views showing the configuration of a distribution box arrangement including a discharge pan and discharge elbow which cooperates with the precision siphon-dosing unit taught by this invention. [0060] FIG. 7 c is a top view of the discharge pan illustrated in FIGS. 7 a and 7 b showing an arrangement of drain holes in the pan and the locations of webs which physically connect the discharge elbow to the pan. [0061] FIGS. 8 a through 8 e are cross sections of the float assembly region of the precision siphon unit of this invention showing the position of the floats and the location of effluent within the unit as the effluent level rises within the unit and falls during siphon flow. [0062] FIG. 9 is a diagram of the configuration of a control box for the precision siphon dosing system taught by this invention [0063] FIG. 10 is a diagram showing a retrofit conversion of an existing conventional septic tank system to the system using the precision siphon dosing system taught by this invention. [0064] FIG. 11 is a diagram showing the configuration of a conventional septic tank waste disposal system. [0065] FIG. 12 is diagram showing a conventional septic system utilizing prior art dosing technology. [0066] FIG. 13 is a cross sectional diagram showing the installation of the precision siphon unit taught by this invention inside a conventional septic tank. [0067] FIG. 14 shows a vertical cross section of the precision siphon-dosing unit taught by a second embodiment of this invention. [0068] FIG. 15 a is an isometric view of the chamber partition of the second embodiment of this invention as seen from above. [0069] FIG. 15 b is an isometric view of the chamber partition of the second embodiment of this invention as seen from below. [0070] FIG. 16 is an isometric drawing showing details of the retainer stem of the second embodiment of this invention. [0071] FIG. 17 is a horizontal cross-section of the second embodiment of this invention denoted by the line A-A in FIG. 14 as viewed from above, showing the upper flow passages 225 which extend from the outer chamber 214 through openings in the inner tube 229 into a space over the metering orifice 228 . [0072] FIG. 18 a through 18 f are vertical cross sections of the of the second embodiment of this invention illustrating the operation thereof by showing the position of the floats and the location of effluent within the unit as the effluent level rises within the unit and falls during siphon flow. [0073] FIG. 19 is a view of a portion of the vertical cross section of the precision siphon-dosing unit taught by a second embodiment of this invention illustrating the clearance volume. DESCRIPTION OF THE PREFERRED EMBODIMENTS [0074] In a first embodiment of this invention the construction and functioning of an economical and reliable true siphon operated dosing system to prolong the life of septic fields of residential homes or commercial buildings is described. Referring first to FIG. 1 , there is shown a cross section of a modern two-compartment septic tank 10 . The tank is generally made of cast concrete but may be constructed of a tough polymer material. The tank 10 is provided with removable covers 11 and 11 a , which provide access to compartments 12 and 13 respectively. In the figures boxed arrows indicate the flow of effluent Septic waste effluent 15 a emanating from a building or a house (not shown) enters the first compartment 12 of the tank 10 through an inlet port 16 . Over time, a settling process takes place as well as fermentation caused by the action of anaerobic bacteria. Solids in the effluent settle to the bottom to form a sludge layer 17 . A scum layer 18 of buoyant solids forms on top of a relatively clear liquid 15 . Clear liquid from the first compartment flows through an opening in a baffle 19 into the second compartment where the settling process continues but far less scum and sludge are produced. [0075] The precision siphon apparatus 20 of the invention is enclosed in an outer housing 21 . Effluent 15 from the clear center zone of the septic tank 10 enters the housing 21 through an inlet conduit 22 at the bottom and rises therein as the flow accumulates in the septic tank. The bottom of the outer housing 21 is conical, and the inlet conduit 22 is pitched down towards the septic tank 10 to facilitate the return of debris to the septic tank during backwash of the siphon unit. The draw down 71 in the septic tank 10 and precision siphon 20 combination, that is, the difference between the highest 23 and lowest 24 liquid levels is determined by the configuration of the precision siphon apparatus 20 . The draw down 71 will be presented later when the functioning of the precision siphon is described. An air vent 26 from the top of outer housing 21 into the top portion of the septic tank above the highest liquid level is provided. A water pipe 27 is connected to the domestic water supply and a control box in the building or house (not shown). Note that the level 23 represents the highest level of septic effluent in the combined septic tank 10 and precision siphon 20 and is determined by a feature of the precision siphon unit, which will be discussed later. [0076] Referring now to FIG. 2 a cross section of the precision siphon-dosing unit 20 as taught by this invention is shown. The isometric view of the core float and spray assembly 28 of the unit shown in FIG. 3 may be of help in visualizing the construction. The float and spray assembly 28 consists of a lower float 29 , an upper float 30 , and a stationary central unit 31 in between, the three components operating within a cylindrical barrel 34 . The two floats have a smaller diameter than the inside diameter of the barrel so that the may travel freely along the axis of the barrel, guided by a central pipe 27 a . The barrel 34 is formed of PVC, high density polyethylene, or other inert polymer material, which will not corrode or deform in the septic effluent environment. The barrel 34 has an inner diameter of about 4 inches. The upper float 30 , the larger of the two floats, has a diameter approximately 1/16 th of an inch smaller than the inner diameter of the barrel 34 . This clearance also allows liquid to flow around the float towards the bottom. The float 30 preferably consists of an injection molded outer shell made of the same material as the barrel 34 . The cavity is filled with a closed cell foam and is weighted to meet the performance requirements for the float 30 . An elastic gasket disk 35 is bonded onto the lower surface of the float 30 . The lower float 29 is also preferably made of the same material as the barrel and the upper float. Both upper and lower floats are designed so that their weight is about half the weight of the volume of displaced liquid respectively. It is the intent that when fully submerged in the liquid, each float has a net upward buoyancy approximately equal to its weight so that it can exert sufficient force to close the respective flow passages without leakage. [0077] The elastic gasket disk 35 is formed of a soft durable rubber or a synthetic elastic polymer. The thickness of the elastic gasket disk is approximately one sixteenth of an inch. The upper float 30 has an additional design requirement that it be of sufficient weight to block the passage of effluent thru the main flow passages 47 by exerting sufficient down force on the seating surfaces 45 and 46 when the liquid is near its highest level 23 . [0078] The weight of the upper float 30 including the gasket disk 35 bonded thereto is preferably between about 10 and 20 percent greater than the maximum upward hydrostatic force exerted on the bottom of the float between the inner and outer sealing seats 45 and 46 in the closed position when the liquid level in the septic tank is at its highest. The volume of the upper float 30 preferably should be such that its net buoyancy when totally immersed in liquid is equal to or more than the combined weight of the upper float 30 and the gasket disk 35 . [0079] Referring to FIG. 5 b , there is shown a top view of the upper float 30 . In operation the upper float becomes buoyant only when liquid enters the upper chamber 64 from above. The liquid passes down along the sides of the upper float 30 . In order to assure free flow of liquid to the base of the float, channels 48 are formed along the sides of the float. [0080] The lower float 29 has an outer segment 36 and a concentric inner segment 37 ( FIG. 2 , not shown in FIG. 3 ) connected to the outer segment by hollow structural webs (not shown). Large flow passages 38 between the inner segment 37 and outer segment 36 assure rapid deployment of the dose once the siphon cycle begins. Vertical sleeves 52 b pass through the body of the lower float allow the passage of retaining bolts 52 . The retaining bolts 52 serve as alignment guides as well as supports when the lower float is not buoyant. An elastic gasket 40 , made of the same material as elastic gasket 35 , is bonded to the top surface of the lower float 29 . The gasket 40 has punched openings corresponding to the flow passages 38 and retaining bolt sleeves 52 b . The hollow cavity inside each float segment is filled with closed cell foam. The combined weight of the float 29 and the elastic gasket 40 should be about half the weight of displaced volume of liquid. The elastic gasket material forms a watertight seal when the lower float rises and presses against drain tubes 42 , which pass through and extend beneath the bottoms of the inner and outer sections of the stationary member 31 as will be explained later. When the lower float is not buoyant it rests upon the wide heads 52 a of the retaining bolts 52 which are threaded into the lower part of the central unit 31 through the lower float. [0081] A top view of the lower float 29 is shown in FIG. 4 . The places of contact 43 where the drain tubes 42 press into the elastic gasket 40 are shown in phantom in the figure. The structural webs which connect the outer 36 and inner 37 segments lie under the regions 39 of the gasket 40 . [0082] The stationary member unit 31 is a solid, cast or molded body which houses the seating surfaces for the two floats. The stationary member 31 is sealed into the barrel 34 and onto the central pipe 27 a to make it water tight all around its outer and inner perimeters. The sealing seats for the lower float 29 consist of the machined sharp edged bottoms of the drain tubes 42 , which project beneath the bottom of the stationary member 31 and have already been mentioned supra. The seating surfaces 45 and 46 for the upper float are machined and sharp edged to seal off the main flow passages 47 which pass through the stationary member 31 and the subjacent lower float 29 , thereby preventing the flow of filtered effluent around the outer portion of the upper float 30 and inner portion around the central pipe 27 , to prevent it from becoming buoyant and prematurely releasing the main surge which will initiate the siphon. FIG. 5 a is a top view of the stationary member 31 showing the configuration of the seals 45 and 46 and the drain tubes 42 . The structural webs 32 between the flow passages 47 connect the inner and outer portions of the stationary member 31 . The retaining bolts 52 which pass through the sleeves 52 b in the lower float are threaded into the underside of the stationary member 31 . The threaded holes 52 c which receive these bolts are shown in phantom in FIG. 5 a. [0083] Returning to FIGS. 2 and 3 , the remaining features of the precision siphon are described. A fine mesh screen filter 53 a is supported on a rigid wire basket 53 b . The basket 53 b is fastened to a lip 25 a on the base of the barrel 34 and is also supported by a second lip 25 b extending from the housing 21 . A rotatable sprinkler tube 50 is attached to the bottom of the central pipe 27 a with a rotatable seal 51 . The sprinkler tube 50 fits within the basket 53 b . A plurality of small openings 54 are arranged along the bottom and one side of the sprinkler tube 50 so that when pressurized water is forced through the openings the sprinkler tube 50 rotates slowly, dislodging and flushing collected particulates from over the entire surface of the filter 53 a in a backwashing action. [0084] The outer housing 21 has a tightly fitting top cover 21 a through which the vent pipe 26 and the water pipe 27 enter the unit. The bottom portion 21 b of the housing 21 . is funnel shaped towards the inlet conduit 22 . [0085] The exit port of the precision siphon-dosing unit consists of a drainpipe 60 emanating at approximately at the same level as the upper float 30 at rest on its seats 45 and 46 . A tube 63 is routed from an opening 62 at the top of the drainpipe 60 to the chamber 64 in the top of the barrel 34 , which is fitted with an airtight cover 65 . [0086] A plurality of spillover ports 66 is located in the top of the annulus between the central pipe 27 a and the extension 27 b . of the water pipe 27 . The spillover ports allow effluent to flow into the upper chamber 64 . The elevation of the spillover ports 66 in the dome 65 a determines the highest level 23 of liquid in the entire system. The lowest liquid level 24 is defined in the vicinity of openings 70 at the base of the barrel 34 . The distance 71 now becomes the draw down of the entire system. [0087] To start the operation of the siphon, on the cue of a pressure sensor, a short burst of high pressure domestic water is delivered into the unit via the water pipe 27 . The water comes out of the spillover ports 66 after the upper float 30 has either lifted or is about to be lifted, the water fills the upper chamber 64 completely, and pushes any remaining air through the siphon tube 63 into the drainpipe 60 and eventually out of the system. The top of central pipe 27 a protrudes into a dome 65 a at the top of the cover 65 and is fastened to the inner pipe 27 b which is the extension of the water pipe 27 into the unit. [0088] The net flow through area of the fine mesh screen filter 53 a is preferably at least about ten times the flow area of the drainpipe 60 . This reduces the impact velocity of the suspended particles against the fine mesh screen thus making it easier to dislodge them by the subsequent backwash action. The net flow through area of a 100 mesh screen is about 45% of the face area and a 150 mesh screen is about 35% open. [0089] The draw down 71 and the diameter of drainpipe 60 determine the internal configuration of the precision siphon unit. If the inner diameter 73 of the drainpipe 60 is fixed at 2 inches nominal, the minimum height of the barrel 34 above the bottom of drainpipe 60 or from the top of the seats 45 and 46 should be the sum of the inner diameter 73 of the drainpipe and the top clearance 74 which must be the height of upper float 30 including the thickness of the soft elastic disk 35 . This height plus the height of spillover ports 66 in the dome 65 a determines the maximum hydrostatic pressure that the upper float 30 must withstand in order to keep the liquid from discharging into the drainpipe 60 . After the liquid level in the annulus between the central pipe 27 a and concentric inner pipe 27 b pipes has reached the spillover ports 66 the upper chamber 64 of the barrel begins to fill. For the upper float 30 to become buoyant it is necessary that liquid should accumulate in the space around the lower half of the float and on the outside of seating surfaces 45 and 46 . The upper float 30 should be immersed in the liquid to a depth, which is near the depth to which the float will sink while freely floating in the liquid. To achieve this accumulation of liquid, a drainpipe uplift 75 is provided. The cross sectional area of the flow passages 38 and 47 must be equal to or greater than the internal flow area of the drain pipe 60 to assure efficient operation of the siphon. [0090] Referring now to FIG. 6 there is shown a block diagram of a complete septic system taught by this invention including a building 92 , from which the septic flow emanates and enters the septic tank 10 and precision siphon 20 assembly (FIG. 1 , 2 ). The drainpipe 60 delivers a dose from the siphon unit to a discharge pan 83 in the distribution box 80 ( FIG. 7 a ), which in turn passes it into the septic field 95 . The pipe 27 is connected to a domestic water supply in the building 92 through a solenoid switch. The dashed line 96 indicates the grade of the land. The pipe 27 must be buried or otherwise insulated to protect from freezing and damage. It is also laid from the building to the dosing unit at a downward pitch to allow for drainage into the dosing unit 20 when the water is turned off. [0091] A control box 94 located within the building 92 , illustrated in detail in FIG. 9 , communicates with the precision siphon unit 20 through the water pipe 27 . When the pipe is empty and at atmospheric pressure, the system senses the dormancy of the siphon cycle. When sensor switch 97 senses a predetermined increase in air pressure in the pipe due to rising effluent in the dosing unit, it indicates that the liquid level in the annulus between inner and outer pipes 27 a and 27 b in the siphon unit 20 is at or near the top. At this time the sensor switch 97 triggers the timer 98 which, in turn, energizes the solenoid valve 99 . The control box 94 receives electrical power to operate its components from the buildings electrical supply E. The solenoid valve 99 operates to deliver timed flows of pressurized water from the buildings domestic water supply W through the water pipe 27 and into the dosing unit, first to initiate the siphon flow and later to backwash the filter 53 a . The timer 98 is set to allow a fixed time to elapse to assure that the siphon cycle is completed before starting the backwash. The timer 98 then actuates the solenoid valve 99 for a predetermined period, typically about five minutes, causing a flow of domestic water to operate the backwash sprinkler 50 for a predetermined time after which operation ceases and the siphon unit 20 is returned to its starting configuration, ready to accumulate the next dose. Using a sensing system as described here, eliminates the need to supply electric service to the siphon unit 20 , which would have been costly and hazardous. [0092] The distribution box 80 , which receives the dosed output of the precision dosing unit 20 through the discharge pipe 60 , also must be modified in order to cooperate with the dosing unit during a siphon flow. [0093] FIG. 7 a shows installation of discharge pan 83 in a standard distribution box 81 . The box 80 is fitted with a cover 82 . The discharge pan 83 is connected to the drainpipe elbow 87 by connecting webs to secure the spacing between the two. The webs 83 a are illustrated in the top view and cross section of the pan assembly shown in FIGS. 7 b and 7 c respectively. There are small openings 85 on the lower side and bottom of the drain pan 83 , which allow the tray to drain after the siphon ceases. During siphon flow, drainage through the small openings 85 is insignificant and the tray is quickly filled and the primary discharge therefrom is overflow. However, it is essential to drain the tray 83 , particularly in colder climates, to avoid freezing. The small openings 85 serve this purpose. The overflow is discharged from the distribution box 80 though the exit opening 90 at the bottom of the box and into the septic field (not shown). [0094] During a siphon operation in the precision siphon unit 20 the filtered effluent discharge therefrom is delivered into the distribution box 80 though the drainpipe 60 entering at the input port 86 . of the distribution box 80 . A discharge elbow 87 is fitted on the end of the pipe 60 to deliver the effluent vertically into the tray 83 . The discharge elbow 87 must extend into the tray 83 so that when the tray is filled, the discharge end of the elbow 87 must be submerged at least one fourth of an inch in the liquid to form an air lock. In order to provide unrestricted flow area, the end of discharge elbow 87 must be above the bottom of the tray 83 one fourth of the inside diameter at the end of the elbow. This geometry is fixed by the connecting structural webs 83 a between the tray 83 and the elbow 87 . [0095] Referring now to FIG. 7 b , there is shown a cross section of the discharge pan at the end of the discharge elbow 87 , illustrating the fastening of the elbow to the pan with structural webs 83 a . FIG. 7 c is a top view of a horizontal cross section of the discharge pan taken at the level b-b′. where four webs and four drainage holes are shown. While additional openings and webs may be added, it is found that the arrangement of openings and webs shown in the figures is sufficient. [0096] The detailed step-by-step operation of the precision siphon of this embodiment will now be described and is illustrated in FIGS. 8 a through 8 e which show the status of the precision siphon unit at several liquid levels 68 . The left hand sides of these figures show the corresponding liquid level 68 a in a portion of the septic tank 10 during each step. [0097] The starting point of the siphon cycle is chosen here to be the point at which the level of septic effluent 15 has reached the openings 70 in the bottom of the barrel 34 . This point is reached on the initial filling of the septic tank 10 and also thereafter when the siphon is broken at the end of each dose delivery. [0098] In FIG. 8 a clear effluent 15 from the septic tank 10 has risen in the unit 20 through the input pipe 22 , (see also FIG. 2 ), passed through the fine mesh screen filter 53 a , where any residual particles are trapped and reached the level of the openings 70 . The liquid level continues to rise in the housing 21 and into the bottom of a cylindrical barrel 34 where it reaches the bottom of a lower float 29 . In the absence of liquid, the lower float 29 rests upon wide heads of the orientation retaining bolts 52 . Referring to FIG. 8 b , as the liquid continues to rise, the lower float 29 lifts from the heads of the support bolts 52 and rises to meet the bottom of the drain tubes 42 . The elastic layer 40 seals off the drain tubes 42 preventing flow into the region of the barrel 34 surrounding the upper float 30 . In FIG. 8 c , the effluent level has risen further in the region between the barrel 34 and the surrounding housing 21 as well as in the water pipe 27 a but the sealed drain tubes 42 have kept the effluent from entering the upper region of the barrel above the stationary member 31 , thereby keeping the upper float 30 from becoming buoyant. [0099] When the liquid rises above the bottom of the water pipe extension 27 b the pressure in the air filled water pipe 27 begins to increase because the solenoid valve in the building is closed. This pressure increase is sensed by the pressure switch 97 in the control box 94 . The pressure switch is set to trigger the timer 98 to start when the pressure reaches a pre-set value which can be determined either by experiment or by calculation from the overall volume of the water pipe. This value is the pressure reached in the pipe 27 approximately when the effluent level is near the level 23 of the spillover ports 66 . [0100] When the level of the effluent finally reaches spillover ports 66 as shown in FIG. 8 c , the liquid begins to overflow 78 into the upper chamber 64 . The elevation 75 in the attached drain pipe 60 prevents the outflow of effluent from the barrel 34 to the drainpipe 60 and allows sufficient accumulation to cause the upper float 30 to become buoyant. Once this occurs the seal between the seating surfaces 45 and 46 and the elastic polymer 35 under the upper float 30 is broken and a sudden rush of effluent passing though the main passages 38 and 47 is released slamming the upper float 30 against the barrel top cover 65 as shown in FIG. 8 d. [0101] At about the same time, the timer, which has been started by the pressure switch, completes a preset time delay and triggers the solenoid valve 99 to open releasing a burst of water through the water pipe 27 driving any residual air from the upper regions of the chamber 64 and the tube 63 causing the onset of siphon flow indicated by the boxed arrow in FIG. 8 d . The burst of water is maintained only for approximately a minute or less after which the timer triggers the solenoid valve 99 to close. [0102] Once the siphon begins and the drain pipe 60 is filled, the pan 83 in the distribution box fills and provides an air tight seal to sustain the siphon until the entire dose is delivered, and the level of effluent in the precision siphon unit 20 drops down to the level of the vent holes 70 in the barrel 34 , allowing air through the vent pipe 26 on top of the septic tank 10 to enter the flow and break the siphon. [0103] The space at the top of septic tank 10 is connected to the atmosphere via the vents in the plumbing system of the building. This keeps the pressure on top of the liquid layer in the tank always at atmospheric level. If this were not so, then immediately after the start of the siphon, a vacuum would start to develop at the top of liquid in the septic tank 10 , and the siphon will cease to operate. [0104] FIG. 8 e shows the liquid levels 68 and 68 a in the siphon unit and in the septic tank respectively near the end of the siphon flow. As the liquid level outside of the barrel 34 continues to drop, the openings 70 are eventually exposed, and air rushes into the lower portion of the barrel. The barrel begins to drain, and the siphon is broken. Now the upper float 30 drops down, and seals off the larger passages 38 and 47 . The lower float 29 also drops down, and opens the heretofore sealed drain tubes 42 which now permit total drainage of the barrel 34 , returning the liquid level in the barrel to the lower limit line 24 . Air now fills the space in the barrel 34 and the water pipe 27 all the way up to the solenoid valve 99 in the control box. [0105] After a short delay the timer causes the solenoid valve 99 to open once again at a time when the siphon cycle has reliably been completed. Pressurized domestic water again flows through the water pipe 27 down the central pipe 27 a of the siphon unit 20 and out the openings 54 of the sprinkler arm 50 , which initiates the post siphon backwash of the filter 53 a within the precision unit. The backwashing is sustained for between 5 and 10 minutes after which the timer closes the solenoid valve 99 . The backwashing time is preset in the timer 98 and is determined mainly by the amount of debris collected during the dosing period which depends on the particular application. Typically the back wash period is between about 5 and 10 minutes. Once the backwashing is complete the water now drains out of the pipe 27 and the cycle is complete. [0106] While in the foregoing embodiment the precision dosing unit 20 was mounted externally on the septic tank 10 , it may also be mounted in the septic tank on the wall having the exit port. FIG. 13 illustrates a suitable installation wherein the unit 20 is supported by its inlet pipe 141 which is now perforated at the top to accommodate the incoming liquid and the returning backwash debris. Alternately the unit may be fastened onto the inner wall of the septic tank 10 (not shown). The vent pipe 26 is now already in the tank. The water pipe 27 and the drain pipe 60 are fed in through side openings in the tank. The compartment cover 11 a provides ready access to the unit. An advantage of this internal mounting is added protection of the unit. [0107] The key component of the present invention, with regard to dosing, is the upper float 30 which, when resting on the sealing surfaces 45 , 46 , blocks the flow of liquid into the drain pipe as well as into the upper region of the barrel surrounding the upper float while the liquid level elsewhere in the siphon unit and in the septic tank rises to a higher level, thereby building up the dose volume and hydrostatic head beneath the float. The maximum head achieved when the liquid level has risen well above the upper float, is not sufficient to force the float off the seals. However, as liquid begins to come out of the spillover ports 66 , and accumulates around the lower half of the upper float, it becomes buoyant, and breaks the seal at 45 and 46 . The sudden rush of liquid from below slams the upper float up against the cover. The resulting surge of liquid, supplied by the large volume in the septic tank, quickly forces most of the air out of the drainpipe. Any remaining air in the system is quickly expelled by the entrance of high-pressure water from pipe 27 via the sprinkler jets 54 and the spillover ports 66 , and the siphon starts. [0108] The lower float 29 serves only to block the flow of liquid into the upper float region through the drain tubes 42 . The drain tubes 42 are needed to drain the liquid remaining in the upper chamber of the barrel after the upper float has dropped back and re-sealed the main flow passages 47 at the end of the siphon cycle. [0109] While the sprinkler backwash assembly plays no role in the dose accumulation and delivery, it is nevertheless a necessary item, which greatly extends the functionality of the fine mesh filter 53 a ; so much so that the filter needs no service even when the septic tank is pumped out and cleaned. [0110] Referring now to FIG. 10 there is shown a block diagram, which illustrates how the precision siphon can be retrofitted into an existing conventional gravity fed septic system. The existing septic tank 100 can be either a single or double compartment unit. The conventional exit port of the septic tank is typically too high for use with the precision siphon system and must therefore be plugged 101 . A new opening 102 is made below the original and the precision siphon unit 103 described supra is mounted onto the septic tank connecting the inlet pipe 104 to the new opening. The siphon units vent tube 105 is also fitted into a second new opening in the top air region of the septic tank 100 . Because the drain pipe required for the precision siphon unit is significantly smaller in diameter (about 2 inches) than the conventional drain pipe (nominally 4 or 5 inches), the new flexible drain pipe 106 is easily inserted within the original drain pipe 107 . Depending on the original layout, this may have to be done prior to mounting the new unit 103 . The new drainpipe is mechanically protected by the original pipe 107 and may be made of a flexible material or of a polymer such as PVC. [0111] The existing distribution box 108 may also be re-used and outfitted with a pan 109 . The end of the drainpipe 106 is fitted with a discharge elbow 110 which is fastened to the pan, having the same relationship to the pan 109 as the corresponding items 87 and 83 in the distribution box 80 supra. The output 111 of the distribution box 108 is left connected to the septic field as is. The input 112 to the septic tank 100 is left undisturbed. Finally a control box and water pipe connection 114 must be made connecting the retrofitted unit to the buildings water and electric supply. This retrofit clearly requires a very minimum (5-10 cubic feet) of excavation and labor making it highly cost effective. [0112] The precision siphon dosing system can be deployed even in those cases where some pitch drop is available, but is insufficient for a simple gravity system, and would normally require the installation of a pump system. If the pitchdrop is enough to maintain a slope of 1 in 200 or even 1 in 300 or 400. The precision siphon dosing can be used as explained below. [0113] If the effluent is cleaned by filtration, as it is in this embodiment, then the customary 1 in 100 pitch is excessive, and there is no justification for it. For comparison the pitch in natural streams or other channels is generally in the range of 1 in 1000, and it still makes the water rapidly flow forward in the downhill direction. Reducing the pitch in half or 1 in 200 or less will still generate sufficient open channel flow velocity to empty the drainpipe quickly after the siphon is broken. It is necessary to empty the drainpipe quickly to prevent freezing of effluent in colder climates. [0114] The precision siphon described by present invention provides the following advantages: 1. It eliminates the need for hazardous and costly electrical service to the septic tanks, thereby eliminating the need for pumps, and other electrical devices in the septic tank. 2. It also eliminates the need for costly, bulky, and separate dosing chambers by effectively using the internal volume of the septic tank, by incorporating into the dose volume the presently unutilized volume represented by the septic tank drop of three inches or more. To make up the entire dose volume it only needs about four inches of the volume below the exit port of the conventional septic tanks. The above-mentioned volume is never available to delay the need for pumping out the sludge from the septic tank, because if the sludge has accumulated to a level to block the passage of liquid through the partition baffle 19 then the system is not functioning and the tank needs to be pumped out anyway. 3. The precision siphon uses the full force of the head provided by the difference in elevation between the bottom of the entrance pipe to the septic tank and the bottom of the distribution box. 4. The precision siphon unit 20 is small enough to fit in a five-gallon bucket. [0119] In a second embodiment of this invention the construction and functioning of an economical and reliable true siphon operated dosing system to prolong the life of septic fields of residential homes or commercial buildings wherein the backwashing of the fine mesh filter is accomplished entirely within the unit without the use of a water pipe or any other support from the building which is serviced by the septic system. The siphon dosing unit is housed entirely within the septic tank and backwashes its filter by return flow of the septic effluent trapped within the unit after the siphon breaks. [0120] Referring to FIG. 14 , there is shown a cross section of the siphon dosing unit 200 housed in a conventional septic tank 10 having a cover 11 a . The outlet pipe 232 of the unit 200 passes through the septic tank wall and to a distribution box configured in the same manner as that of the first embodiment described supra and shown in FIGS. 7 a and 7 b . The unit 200 is supported within the tank either by a post structure as shown in FIG. 13 or by the exit pipe 232 itself. [0121] A chamber partition 209 supports both upper 221 and lower 205 floats. The chamber partition is sandwiched between the upper 215 and lower 235 portions of the barrel housing of the dosing unit, providing an airtight connection, and is shown in greater detail in FIGS. 15 a and 15 b . The chamber partition 209 controls flow between upper and lower chambers by operation of the floats 205 and 221 . [0122] A siphon tube 204 , supported on the bottom flange 234 , passes vertically through and is sealed, to make the connection airtight, onto the top cover 226 of the unit 200 , and extends several inches above the highest liquid level 23 in the septic tank 10 , thereby assuring a continuous exposure of the opening of this tube to atmosphere. A tee 270 is included on top of siphon tube to prevent debris from entering the tube. A hole 203 on the side and near the bottom of the siphon tube 204 determines the lowest liquid level 24 in the septic tank 10 . As in the first embodiment, the siphon dosing operates between these two levels. The difference between these two levels, as in the first embodiment is referred to as the drawdown 71 of the dosing unit. [0123] A fine mesh filter screen 201 is sandwiched across the bottom input collar 237 of the dosing unit 200 between the inner collar 236 and the locking collar 238 . The locking collar 238 may be a snap-ring/o-ring combination permitting easy removal and replacement of the filter 201 . [0124] Referring now also to FIG. 15 a , the chamber partition 209 is provided with multiple openings 217 which connect the outer chamber 214 (the annular space between the outer cylindrical barrel 215 and the inner cylindrical barrel 216 ) of the dosing unit with the lower chamber 202 , to enable liquid to freely flow between the upper and lower chambers. In the same pattern, opening 204 a provides a passthrough for the siphon tube 204 , while the groove 216 a receives the bottom of the inner cylindrical barrel which is sealed thereto, separating the inner 218 and outer 214 chambers. [0125] The outer drain passages 211 (i.e., outside of upper float seals 223 ) pass through the three structural webs 239 to connect to the vertical inner drain passages 210 , which drain into the space between the lower seals 207 and 208 . The lower float 205 is suspended from the center of the chamber partition 203 by a retainer stem 212 which also contains a drain passage 230 to empty the central tube 229 at the end of the siphon cycle. The features of the lower float can be best seen in FIG. 16 where the drain 230 in the retainer stem 212 is illustrated showing a vertical passage 230 a which connects to a horizontal passage 230 b . On assembly the retainer stem 212 is glued into the opening in the center of the lower float 205 . When assembled, the horizontal passage 230 b in the retainer stem is just above the top of the sealing gasket 206 as shown in FIG. 14 . In operation, when the lower float 205 rises, the gasket 206 engages the inner and outer circular seats 207 and, 208 , thereby sealing off the openings from drain passages 210 and 211 , as well as the passage 230 in the retainer stem 212 , thereby preventing liquid from flowing into the upper chamber 218 as well as into the central tube 229 . [0126] The circular seats 207 and 208 engaged by the lower float 205 as well as the circular seats 222 and 223 engaged by the upper float gasket 222 are machined on the bottom and top surfaces respectively of the chamber partition 209 which is important in order to obtain a tight seal. FIG. 15 b , illustrating the underside of the chamber partition 209 , shows the lower float sealing surfaces 207 and 208 and the openings 210 of the vertical drain passages. [0127] The top cover of the siphon dosing unit 200 contains the features for filling the upper chamber 218 and starting the siphon flow when the septic fluid level reaches its highest level 23 . FIG. 17 illustrates a section of the top cover 226 perpendicular to the line A-A′ in FIG. 14 . Referring now to FIG. 14 with reference to FIG. 17 there are three passages 225 in the top cover 226 through which septic effluent flows from the outer chamber 214 into the inner tube 229 when the highest level 23 in the septic tank has been reached. The effluent passes through metering orifice 228 located within the top of the inner tube 229 . When tube 229 is filled liquid overflows through openings 231 into the inner chamber 218 , eventually causing the upper float assembly 221 , 220 to become buoyant and starting the siphon flow. This process is similar to that described in the first embodiment and will be detailed for the present embodiment later. The elevated bend 235 in the discharge tube 232 has the same function as in the first embodiment and is designed to permit just the right amount of liquid to accumulate to make the upper float assembly 221 , 220 buoyant enough to lift, and to start the rapid onset of the siphon flow. The volume of the upper float assembly 221 , 220 is such that its maximum buoyancy when totally immersed in liquid is about twice its weight. For the upper float assembly 221 , 220 to become buoyant it is necessary that liquid should accumulate in the space around the lower half of the float and on the outside of seating surfaces 222 and 223 . The upper float assembly 221 , 220 should be immersed in the liquid to a depth, which is near the depth to which the float will sink while freely floating in the liquid. To achieve this accumulation of liquid, a discharge tube uplift 235 is provided. [0128] Referring now to FIG. 18 a , the operational cycle of the second embodiment of this invention will be described. In the figure the septic liquid level is at its lowest 24 . The lower float is suspended from the retainer stem 212 . As more liquid enters the septic tank 10 , the level in the dosing unit 200 rises with liquid flowing through the fine mesh screen filter 201 and into the lower chamber 202 . In FIG. 18 b the level has risen sufficiently to cause the lower float assembly to become buoyant, rising to seal the passages 210 to the upper chamber 218 as well as the passage 230 at the base of the inner tube 229 . [0129] In FIG. 18 c the liquid continues to rise unobstructed into the siphon tube 204 through siphon port 203 , and into the outer chamber 214 through openings 217 in the chamber partition 209 . In FIG. 18 c , when the liquid level has reached the maximum level 23 and begins to flow through the passages 225 in the top cover 226 and down through the opening 228 a in the metering orifice 228 , thereby beginning to fill 252 the inner tube 229 from the top. [0130] When the liquid level in the inner tube 229 reaches the overflow passages 231 the liquid begins to spill over 254 into the inner chamber 218 as shown in FIG. 18 d . In the figure, enough liquid has flowed into the inner chamber 218 to bring the level in the discharge tube 232 to near the top of the bend 235 , and the upper float 221 is about to break free. [0131] Further rise of the liquid level in the inner chamber 218 , but before overflow at the bend 235 occurs, provides enough incremental buoyancy (by design) to lift the upper float 221 , when said overflow occurs and raise it to the bottom of top cover 226 . The upper float assembly 221 pushes the air in the inner chamber 218 into the discharge tube 232 . There is ample clearance between the float 221 and inner wall of the inner barrel 216 and the outer wall of the inner tube 229 to allow the escape of air. [0132] In a very short period (a few seconds) the inner chamber 218 is filled with liquid and the discharge pipe 232 starts filling up. Quickly thereafter all the air in the system is pushed out through the discharge pipe 232 and the discharge pan 83 in the distribution box 80 (see FIG. 7 a ), and the siphon operation begins. [0133] As the siphon proceeds, the liquid level in the septic tank 10 , siphon tube 204 , and the outer chamber of the dosing unit 200 , begins to drop. Referring now to FIG. 18 e , when the liquid level in the septic tank 10 and in the siphon tube 204 drops to near its lowest level 24 , the siphon port 203 becomes exposed to air. Air 260 begins to bubble in and through the annular passages 217 and 219 and starts entering simultaneously into the inner chamber 218 and outer chamber 214 , thus breaking the siphon, and causing the trapped liquid to begin to drain downwards. Liquid from the outer and inner chambers flows 262 back into the septic tank 10 through the fine mesh filter 201 . This flow backwashes and cleans the filter. [0134] After a few seconds the upper float assembly 221 , 220 starts to drop. Liquid trapped in the outer chamber 214 only starts to drop once air bubbles enter the device, and flow through passages 217 . Trapped liquid displaced by air in chamber 218 flows down through passages 219 . [0135] Before the inner chamber 218 is fully emptied, the upper float assembly 221 , 220 falls back onto the seals 222 and 223 , thereby blocking further flow of liquid from the inner chamber 218 into the lower chamber 202 , and leaving residual liquid in a clearance volume 266 , as shown in FIG. 18 f . The clearance volume 266 is illustrated in FIG. 19 and represents the maximum amount of liquid that can remain in the upper chamber after the upper float assembly has dropped. The residual liquid 267 ( FIG. 18 f ) in the clearance volume 266 must be removed so that upper float assembly 221 , 220 does not rise prematurely during the next siphon cycle. [0136] Liquid continues to flow back into the septic tank to seek equilibrium. Eventually the lower float 205 drops to its suspended position, releasing the seals against the drain passages 210 / 211 and thereby allowing the residual liquid in the clearance volume 266 , as well as liquid in the inner tube 229 , to drain back into the lower chamber, through passages 210 / 211 and through discharge tube 232 , respectively. At the same time the inner tube drains through the passage 230 in the stem retainer 212 completing the filter backwash and returning the liquid level in the dosing unit to the initial condition shown in FIG. 18 a . When all the liquid above the lowest liquid level 24 has drained back the siphon cycle is completed, and the unit is ready for the next cycle. [0137] While this invention has been particularly shown and described with reference to the preferred embodiments thereof, it will be understood by those skilled in the art that various changes in form and details may be made without departing from the spirit, principles, and scope of the invention.

4y

BACKGROUND OF THE INVENTION [0001] 1. Field of the Invention [0002] The present invention relates generally to locks and more particularly, to a zipper lock that can be unlocked forcibly. [0003] 2. Description of the Related Art [0004] A luggage or any other similar bag or case that is provided with a zipper may be mounted with a zipper lock to lock the two zipper tabs together, prohibiting others to open the zipper. [0005] Conventionally, a combination lock having a set of notched rotating discs is widely used as a zipper lock. When opening this kind of zipper lock, the user must rotate the notched rotating discs to show the preset combination. If the user forgets the correct combination, the user cannot open the zipper lock, and must deliver the luggage or bag to the distributor or a locksmith to open the zipper lock. Therefore, the aforesaid conventional zipper lock is not a convenient design, and may bring trouble to the user. SUMMARY OF THE INVENTION [0006] The present invention has been accomplished under the circumstances in view. It is the primary objective of the present invention to provide a zipper lock, which is the assembly of a combination lock and a pin tumbler lock and allows the user to open the zipper lock through the combination lock or the pin tumbler lock selectively, enhancing the convenience of use. [0007] To achieve this objective of the present invention, the zipper lock comprises a lock housing in which a combination lock, a pin tumbler lock, a swivel member and first and second latches engageable with two pull-tabs of a zipper which are insertable into the lock housing are mounted. When the combination lock is set in an unlocked manner from a locked manner, the swivel member is forced by a part of the combination lock to move to a position where the swivel member is disengaged from the latches for allowing movement of the latches relative to the lock housing such that the two pull-tabs of the zipper can be inserted into or pulled away from the lock housing to be engaged with or disengaged from the latches. When the combination lock is set in the locked manner from the unlocked manner, the swivel member is engageable with the latches to prohibit movement of the latches. The pin tumbler lock has an actuating block rotatable with the key to move the swivel member away from the latches for allowing movement of the latches Therefore, the user is allowed to selectively unlock the zipper lock either by means of the combination lock or the pin tumbler lock. [0008] In a preferred embodiment of the present invention, the lock housing has a first lock notch and a second lock notch. The first latch has a locking rod movable in and out of the first lock notch. The second latch has a locking rod movable in and out of the second lock notch. Two spring members respectively bias the first latch and the second latch to support the first latch and the second latch in the first lock notch and the second lock notch in normal manner. The swivel member is moveable between a first position where the swivel member is stoppable against the first latch and the second latch to prohibit movement of the first latch and the second latch, and a second position where the swivel member is spaced from the first latch and the second latch for allowing movement of the first latch and the second latch relative to the lock housing. The combination lock includes a plurality of number wheels and a movable plate coupled to the number wheels. The number wheels each have a retaining notch. The movable plate has a plurality of retaining protrusions and a push portion. The retaining protrusions engage the retaining notches of the number wheels respectively and the push portion is stopped against the swivel member to bias the swivel member from the first position to the second position when the combination lock is unlocked. The retaining protrusions are disengaged from the retaining notches of the number wheels and the push portion is disengaged from the swivel member when the combination lock is locked. The pin tumbler lock is rotatable between a locking position and an unlocking position. The pin tumbler lock has an actuating block stopped against the swivel member when the pin tumbler lock is in the unlocking position. The actuating block is separated from the swivel member when the pin tumbler lock is in the locking position. [0009] Further scope of applicability of the present invention will become apparent from the detailed description given hereinafter. However, it should be understood that the detailed description and specific examples, while indicating preferred embodiments of the invention, are given by way of illustration only, since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description. BRIEF DESCRIPTION OF THE DRAWINGS [0010] The present invention will become more fully understood from the detailed description given herein below and the accompanying drawings which are given by way of illustration only, and thus are not limitative of the present invention, and wherein: [0011] FIG. 1 is a perspective view of a zipper lock according to a preferred embodiment of the present invention; [0012] FIG. 2 is an exploded view of the zipper lock according to the preferred embodiment of the present invention; [0013] FIG. 3 is a bottom view of the zipper lock of the present invention after removal of the bottom cover plate, showing that the combination lock is unlocked; [0014] FIG. 4 is similar to FIG. 3 but showing that the combination lock is locked, and FIG. 5 is similar to FIG. 3 but showing that the pin tumbler lock is unlocked. DETAILED DESCRIPTION OF THE INVENTION [0015] As shown in FIGS. 1 and 2 , a zipper lock 10 in accordance with a preferred embodiment of the present invention comprises a lock housing 20 (see FIG. 1 ), a first latch 30 , a first spring member 40 , a second latch 50 , a second spring member 60 , a swivel member 70 , a combination lock 80 , and a pin tumbler lock 90 . [0016] The lock housing 20 includes a casing 21 and a bottom cover plate 22 . The bottom cover plate 22 is covered on the bottom open side of the casing 21 , defining with the casing 21 an accommodation chamber 23 . The casing 21 has two lock notches 212 at one lateral sidewall thereof in communication with the accommodation chamber 23 for receiving the two pull-tabs (not shown) of a zipper (not shown), three through holes (not shown) at the other lateral sidewall in communication with the accommodation chamber 23 , a pin tumbler lock hole 214 at the top wall in communication with the accommodation chamber 23 , two inside flanges, namely, the first inside flange 24 and the second inside flange 25 protruding from the inside wall and respectively extending around the lock notches 212 , two inside openings 242 and 252 respectively formed on the inside flanges 24 and 25 , an inside stop plate 26 protruding from the inside wall and facing the opening 252 on second inside flange 25 , and an inside pivot rod 27 protruding from the inside wall and disposed adjacent to the stop plate 26 . [0017] The first latch 30 is mounted in the accommodation chamber 23 of the lock housing 20 , having a protrusion 32 at its one side, a locking rod 34 extending from one side of the protrusion 32 and inserted through the opening 242 on the first inside flange 24 corresponding to one lock notch 212 and stopped against the inner surface of the first inside flange 24 (see FIG. 4 ), and a retaining post 36 protruding from the other side of the protrusion 32 . The locking rod 34 has a beveled edge 342 . [0018] The first spring member 40 is sleeved onto the retaining post 36 of the first latch 30 and stopped between the protrusion 32 of the first latch 30 and the outer surface of the second inside flange 25 . [0019] The second latch 50 is mounted in the accommodation chamber 23 of the lock housing 20 below the first latch 30 , having a protrusion 52 perpendicularly extending from its one end, a locking rod 54 extending from one side of the protrusion 52 and inserted through the opening 252 on the second inside flange 25 corresponding to the other lock notch 212 and stopped against the inner surface of the associating second flange 25 (see FIG. 4 ), and a retaining post 56 protruding from the other side of the protrusion 52 . The locking rod 54 has a beveled edge 542 . [0020] The second spring member 40 is sleeved onto the retaining post 56 of the second latch 50 and stopped between the protrusion 52 of the second latch 50 and the stop plate 26 . [0021] The swivel member 70 has a pivot portion 71 , which defines a pivot hole 712 that is coupled to the inside pivot rod 27 for allowing turning of the swivel member 70 about the inside pivot rod 27 of the lock housing 20 , a torsional spring 72 , which works in such a manner to allow turning of the swivel member 70 about the inside pivot rod 27 within a limited angle between a first position and a second position, a stop portion 73 extending from the periphery of the pivot portion 71 , a wing portion 74 , and a connection portion 75 connected between the pivot portion 71 and the wing portion 74 . When the swivel member 70 is in the first position as shown in FIG. 4 , the stop portion 73 is stoppable against the first latch 30 and the second latch 50 to prohibit movement of the first latch 30 and the second latch 50 relative to the lock housing 20 . When the swivel member 70 is in the second position as shown in FIG. 3 , the stop portion 73 is moved away from the first latch 30 and the second latch 50 , allowing movement of the first latch 30 and the second latch 50 relative to the lock housing 20 . [0022] The combination lock 80 is mounted in the accommodation chamber 23 of the lock housing 20 , including three number wheel assemblies 81 , a movable plate 82 and a spring member 86 . Each number wheel assembly 81 includes a rotating disc (with inscribed numerals) 83 , a retaining wheel 84 , and a spring member 85 . The rotating discs 83 are respectively disposed corresponding to the through holes of the casing 21 and exposed to the outside of the lock housing 20 . The retaining wheels 84 are respectively disposed at the bottom side of the rotating discs 83 , each having a retaining notch 842 . The spring members 85 are respectively connected between the bottom side of each of the retaining wheels 84 and the bottom cover plate 22 of the lock housing 20 . The movable plate 82 has three receiving open spaces 822 for receiving the retaining wheels 84 respectively, three retaining protrusions 824 respectively suspending in the receiving open spaces 822 at one side, and a push portion 826 . The push portion 826 has a beveled edge 828 . Further, the spring member 86 is connected between one end of the movable plate 82 and a part of the casing 21 . [0023] The pin tumbler lock 90 is mounted in the pin tumbler lock hole 214 of the casing 2 I of the lock housing 20 , having a keyway 92 in the top side and a bottom actuation member 94 at the bottom side. The bottom actuating block 94 has a beveled edge 942 . [0024] When wanting to open the zipper lock 10 , rotate the rotating discs 81 to show the set permutation of the combination lock 80 , and therefore the combination lock 80 is unlocked. At this time, as shown in FIG. 3 , the retaining notches 842 of the retaining wheels 84 are respectively aimed at the retaining protrusions 824 of the movable plate 82 , and the movable plate 82 is forced by the spring power of the spring member 86 toward the rotating discs 81 to engage the retaining protrusions 824 into the retaining notches 842 of the retaining wheels 84 , and at the same time the beveled edge 828 of the push portion 826 of the movable plate 82 is forced against the connection portion 75 of the swivel member 70 to turn the swivel member 70 from the first position to the second position. Thus, the stop portion 73 of the swivel member 70 is disengaged from the first latch 30 and the second latch 50 , making the first latch 30 and the second latch 50 moveable. The user can thus insert the two pull-tabs of the zipper into the two lock notches 212 of the casing 21 . When inserting the pull-tabs of the zipper into the two lock notches 212 of the casing 21 , the pull-tabs are forced against the beveled edge 342 of the locking rod 34 of the first latch 30 and the beveled edge 542 of the locking rod 54 of the second latch 50 respectively, moving the first latch 30 and the second latch 50 in direction toward the pin tumbler lock 90 , and therefore the spring members 40 and 60 are compressed. After the pull-tabs of the zipper have been inserted into position in the respective two lock notches 212 of the casing 21 , the first latch 30 and the second latch 50 are forced by the spring power of the associating spring members 40 and 60 to move the respective locking rods 34 and 54 into the eyelets (not shown) of the pull-tabs of the zipper. Thereafter, the user can then rotate the rotating discs 81 to move the retaining notches 842 of the retaining wheels 84 away from the retaining protrusions 824 of the movable plate 82 . At this time, the retaining wheels 84 force the movable plate 82 outwards to disengage the push portion 826 from the connection portion 75 of the swivel member 70 , allowing the swivel member 70 to be returned by the spring power of the torsional spring 72 from the second position to the former first position to have the stop portion 73 of the swivel member 70 be stopped against the first latch 30 and the second latch 50 again (see FIG. 4 ), and therefore the two pull-tabs of the zipper are locked to the lock notches 212 of the casing 21 . [0025] Referring to FIG. 5 , if the user cannot remember the correct permutation of the combination lock 80 , the user can insert the key into the keyway 92 of the pin tumbler lock 90 and rotate the key to move the beveled edge 942 of the bottom actuating block 94 against the wing portion 74 of the swivel member 70 , thereby moving the swivel member 70 from the first position to the second position where the the stop portion 73 of the swivel member 70 is disengaged from the first latch 30 and the second latch 50 to unlock the pull-tabs of the zipper. In other words, the user can unlock the pull-tabs of the zipper by using either the combination lock 80 or the pin tumbler lock 90 . [0026] The invention being thus described, it will be obvious that the same may be varied in many ways. Such variations are not to be regarded as a departure from the spirit and scope of the invention, and all such modifications as would be obvious to one skilled in the art are intended to be included within the scope of the following claims.

4y

FIELD OF INVENTION The current invention relates to compositions for reducing the linting and dusting tendency of printing paper during printing. Moreover, the invention relates to a coated paper, comprising such composition, and use thereof. BACKGROUND Linting and dusting are terms used to define the tendency of a paper surface to shed loose and weakly bonded particles and accumulate these on the blanket during offset printing. Linting is a fibre, fibre fragment, ray cell or vessel element removal phenomenon related to both pulp and paper properties as well as printing conditions. Dusting is the result of loss of filler or other fine materials that are not firmly attached to the paper surface. When removed during printing, linting and dusting materials easily accumulate on the printing blanket, especially in the first printing unit when multiple printing units are used. The mechanism of linting is not entirely understood and solving problems related to linting may be difficult processes. The mechanism of linting can generally be ascribed the inter-fibre bonding strength on the paper surface. That is to say, lint and dust are removed from the surface of the paper when the external forces exceed the forces holding the sheet together. Picking is another aspect when it comes to the printability of paper. Picking stands for the pulling out of fibres or small clusters of fibres. Picking may in extreme cases result in sheet delamination, whereby large uniform areas are lifted from the paper surface. Picking occurs when the split resistance of the ink and hence the stress perpendicular to the paper surface exceeds the local strength of the paper surface at the outlet of the nip. Picking may result in linting. Material removed from the paper surface consists mostly of poorly fibrillated fibres, non-fibrous cell materials (such as ray cells, vessels, bagasse pith etc) as well as fibre fragments, fines and debris. It is well-known that coarse and stiff fibres require a higher energy input during refining in order to minimize linting. The energy input hence is probably one of the more important parameters affecting linting. Surface sizing is a known procedure for alleviating the linting tendency of newsprint. The linting problem cannot, however, be regarded solely as a papermaking problem. Printing press variables have a strong influence on paper linting performance and must by carefully controlled. Important press room factors include edition size, web lead configuration through the press (departure angle etc.), ink properties (viscosity and tack) and the fountain solution (quantity and quality). Linting can also be caused by an incorrect ink/water balance. From earlier studies, it can be concluded that several press variables often contribute to linting. Linting results in deterioration of the print quality to the point where the press must by stopped and cleaned. This cleaning process is both tedious and costly. The linting tendency of paper can therefore have a strong effect on pressroom efficiency, particularly in high volume printing operations such as newspaper production. The continued trend towards increased use of offset printing in high volume multi-colour printing operations has made linting a considerable economic problem and a source of frequent customer complaints. Consequently, there exists a need for improved sheets of paper with reduced linting and dusting propensity and additionally compositions for affecting said improvements. SHORT DESCRIPTION OF THE INVENTION In a first aspect of the current invention, there is provided a composition for coating of printing paper, said composition comprising microfibrillated cellulose (herein below referred to as MFC) and one or more polysaccharide hydrocolloid to reduce the linting and dusting propensity of said paper during printing. The polysaccharide hydrololloid may be any starch or gum. Gums that are suitably used in accordance with the current invention are exemplified by the group comprising locust bean gum, karaya gum, xanthan gum, gum arabic, gum ghatti, gum agar, pectin, gum targacanth, alginates, cellulose gums (e.g carboxymethyl cellulose, alkylcellulose, hydroxyalkylcellulose, hydroxyethylcellulose, hydroxypropylcellulose), guar gum, tamarind gum, and carrageenan. In one embodiment of the invention, the polysaccharide hydrocolloid is starch. The starch used may be any commercially available starch, comprising any combination of the two starch polymers amylase and amylopectin. The starch may be used in its native, in an anionic or cationic form. The starch may be modified using any of the following treatments; enzymes, thermo treatment, APS peroxide, etherification, esterification, oxidation (e.g. hypochlorite), acid hydrolysis, dextrinose, catioinization, hydroxyethylation, carboxymethylation, and acetylation. Additionally, other polysaccharide hydrocolloids selected from the group consisting of guar, tamarind, locust, karaya cellulose ether, xanthan, pectin, alginates, carrageenin, or agar may form part of the starch formulation binder. The composition may consist exclusively of MFC and polysaccharide hydrocolloid(s), such as starch. Exemplary plants from which starch may be obtained comprise potatoes, cassava, barley, wheat, corn, rice, tapioca, arrowroot, sago. Although a variety of different starches may be used, it will be recognized by those skilled in the art that differences in amylose content, branching, molecular weight and content of native lipid between various starch varieties will result in different chemical and physical properties and will thus influence the characteristics of the coating. Processes for the manufacture of MFC are disclosed in e.g. WO2007/091942 and Swedish patent application SE 0800807-0. Said microfibrillated cellulose (also commonly referred to as nanocellulose, nanofibrillated cellulose, nanofibres, microfibers) may be manufactured from any cellulose containing fibres, which may be found in chemical pulp, mechanical pulp, thermomechanical pulp, chemi(thermo)mechanical pulp (CMP or CTMP). The pulp used may consist of pulp from hardwood, softwood or a combination of both types of wood. The pulp may e.g. contain a mixture of pine and spruce or a mixture of birch and spruce. The chemical pulps that may be used in accordance with the present invention include all types of chemical wood-based pulps, such as bleached, half-bleached and unbleached sulphite, kraft and soda pulps, and mixtures or combinations of these. The pulp may during manufacture of MFC be of any consistency, ranging from low consistency through medium consistency to high consistency. The fibre origin may be wood or any other cellulose containing plant. Normally, said fibres are treated in suspension with the aid of a mechanical comminution device, and said device may e.g. be a refiner, a fluidizer, a homogenizer or a microfluidizer. A pre-treatment of the fibres may also be performed prior to the treatment in said device. Of the component parts of the composition, the polysaccharide hydrocolloid has a better ability than the MFC to penetrate the paper during coating, whereas the upper part of the coating to a greater extent consists of MFC. MFC as such has problems penetrating the paper, due to its high water retention capacity and particle size. Consequently, there exists a great synergistic effect of the composition disclosed. The advantage of the composition of MFC and the polysaccharide hydrocolloid is three-fold: it offers a coating that holds the linting particles in place, partially anchors the particles internally in the sheet and anchors the MFC layer to the sheet. The polysaccharide hydrocolloid used may be branched or unbranched, and may be native or modified, such as nonionic ethers, anionicilly modified or cationic. When choosing the combination of MFC and polysaccharide hydrocolloid, attention is directed towards reducing the agglomeration propensity of the combination. This may be seen to by adjustment of the pH or salt content of the combination. Adjustment of said variables is well within the competence of the person skilled in the art. One measure to reduce the agglomeration propensity is to ensure that the MFC and polysaccharide hydrocolloid used have substantially the same charge. For example, anionic MFC may be combined with anionic polysaccharide hydrocolloid to minimize agglomeration. In one embodiment of the invention, the composition comprising MFC and the polysaccharide hydrocolloid comprises 1-90% by weight of MFC, with the balance comprising a polysaccharide hydrocolloid. In another embodiment of the invention, said composition comprises 2-50% by weight of MFC, with the balance comprising polysaccharide hydrocolloid. In yet an embodiment of the invention, the composition comprises 3-25% by weight of MFC, with the balance comprising polysaccharide hydrocolloid. In another embodiment, the composition comprises 5-15% by weight of MFC, with the balance comprising the polysaccharide hydrocolloid. % by weight is as used herein calculated based on the total weight of the respective composition or mixture, unless defined otherwise. The compositions of the invention are suitable for both coating and surface sizing applications. In one embodiment, there is provided a paper coated with the composition comprising MFC and the polysaccharide hydrocolloid. This paper has reduced linting propensity, while at the same time retaining acceptable ink absorbency. The ink absorbency may be in the same range as that of a conventional, uncoated paper. In a second aspect of the invention, there is provided a coated paper, comprising a first layer of the polysaccharide hydrocolloid, and a second layer of MFC. The number of layers may be varied according to preferences. The polysaccharide hydrocolloid layer(s) form a foundation, to which the MFC is sufficiently bound. The polysaccharide hydrocolloid, enhances the interface between the MFC layer(s) and the paper surface. Thereby, the linting and dusting propensity of the final paper is reduced. MFC may be used to e.g. reinforce the surface characteristics of e.g. commercial newsprint sheet. The polysaccharide hydrocolloid layer(s) of the coated paper in one embodiment comprises starch chosen from the group consisting of branched or unbranched native starch, anionic starch and cationic starch, peroxidized starch, etherified starch, esterified starch, oxidized starch, hydrolyzed starch, dextrinozed, starch hydroxyethylated starch, and acetylated starch, respectively. The starch used may be any commercially available starch, comprising any combination of the two starch polymers amylase and amylopectine. In another embodiment of the invention, the polysaccharide hydrocolloid is chosen from the group consisting of locust bean gum, karaya gum, xanthan gum, gum arabic, gum ghatti, pectin, targacanth, alginates, cellulose gums, guar gum, tamarind gum. In one embodiment, the coated paper has an amount of MFC in the region of 0.1-60 g/m 2 of the paper product. In another embodiment, the coated paper has an amount of MFC in the region of 0.5-40 g/m 2 of the paper. In yet an embodiment, the coated paper has an amount of MFC in the region of 1-30 g/m 2 of the paper. In still another embodiment, the coated paper has an amount of MFC in the region of 3-20 g/m 2 of the paper. In a third aspect of the invention there is provided use of the composition comprising starch and MFC to provide a barrier on a paper. In a fourth aspect of the invention, there is provided use of the paper coated with the composition comprising MFC and starch as a barrier. In a fifth aspect of the invention, there is provided a method for reducing the linting and/or dusting of a paper, comprising coating of a paper with any composition as herein described. “Paper” as used herein comprises any paper, sheet of paper and any other wood fibre based product. The present invention will now be described with reference to the accompanying drawings. The embodiments and examples shall merely be seen as an illustration of the spirit and scope of the current invention, and in no way whatsoever as a limitation. SHORT DESCRIPTION OF THE FIGURES FIG. 1 shows the linting tendency of reference sheets with different amounts of C-starch for internal treatments. FIG. 2 shows the linting tendency of sheets (with 2% C-starch, internal treatment) which were surface treated using different chemicals at similar coating levels. FIG. 3 shows the linting tendency of sheet (with 5% C-starch, internal treatment) which were surface treated using different chemicals at similar coating levels. FIG. 4 shows images on the print disc at end of the print speed=3.18 m/s, whereby the reference sheets were treated without any surface chemical. FIG. 5 shows images on the print disc at delaminating critical print speed=4.64 m/s, whereby the reference sheets were coated with MFC at 2.1 g/m2. FIG. 6 shows the linting propensity of blank sheets with different chemical treatments at the same addition level (1%). FIG. 7 shows the linting propensity of blank sheets with different chemical treatments at the same addition level (2%). FIG. 8 shows oil drop volume vs. time, whereby different chemical treatments have been performed. FIG. 9 shows oil absorbency (displayed as volume decrease of oil droplet between 1 and 5 s of contact time) of sheets with different chemical treatments. FIG. 10 shows the linting tendency of commercial newsprint with different levels of MFC coatings. FIG. 11 shows the fibre rising tendency (FRT) results of commercial newsprint with different amounts of MFC surface treatment. FIG. 12 shows ESEM micrographs of sheet surfaces with different coatings. FIG. 13 shows ESEM micrographs of cross-sections of sheets with different coatings. DETAILED DESCRIPTION OF THE INVENTION Material Pulp and Paper Materials In the linting experiments, a never dried commercial spruce ( Picea abies ) thermo mechanical pulp (TMP) from Hallsta Paper mill (Holmen Paper, Sweden), was used. For preservation reasons, the pulp was frozen and thawn. After the pulp was thawned, the freeness in deionized water was 173 CSF (ISO 5267-2). Freeness measured at the mill was 102 CSF. In another set of linting experiments a commercial newsprint (improved newsprint, grammage=60 g/m2, Bendtsen surface roughness=150-230 ml/min) was used (Hallsta Paper mill, Holmen Paper, Sweden). In the manufacture of MFC, a commercial sulphite softwood-dissolving pulp (Domsjo Dissolving Plus; Domsjö Fabriker AB, Sweden), from 60% Norway spruce ( Picea abies ) and 40% Scottish Pine ( Pinus sylvestris ), with a hemicellulose content of 4.5% (measured as solubility in 18% NaOH) and a lignin content of 0.6% was used. The pulp was thoroughly washed with deionized water and used in its never-dried form. Internal Treatment Chemicals Cationic Starch (C-Starch) For the internal treatments, a commercial potato C-starch was used (Amylofax PW, Degree of substitution (D.S.)=0.035, Avebe, The Netherlands). In order to gelatinise the C-starch, the C-starch was mixed with 200 mL deionized water to a concentration of around 1.5 wt-% and was heated to 90-95° C. and kept at this temperature for 15 minutes. After cooling, the solution was diluted to a volume of 1 L. Anionic Polyacrylamide (A-PAM) A-PAM (PL156, anionic charge density: 40 mole-%, Ciba, UK) was used as an adjuvant to retain C-starch (by complexation) at high C-starch dosages. In order to prepare an A-PAM solution, 0.125 g of A-PAM was soaked in 1.5 ml ethanol for 2 minutes. After an addition of 50 ml deionized water, the composition was mixed thoroughly for 2 minutes. Then the composition was stirred for 2 hours and left over night without stirring. Surface Treatment Chemicals Anionic Starch (A-Starch) In the surface size treatments, an anionic oxidized potato starch (Perlcoat 158, charge density=153.2 μeq/g, Lyckeby Industrial AB, Sweden) was employed. In order to gelatinise the A-starch, the A-starch was mixed with deionized water to a concentration of around 10 wt-% and was then heated to 95° C. and kept at this temperature for 15 minutes. The pH was adjusted to pH 8 prior to the sizing experiments. Micro Fibrillated Cellulose (MFC) The dissolving softwood-pulp was first carboxymethylated to a D.S. of approximately 0.1 following a method described elsewhere (Wågberg, L., Decher, G., Norgren, M. Lindström, T., Ankerfors, M., and Axnäs, K. Langmuir (2008), 24(3), 784-795). Thereafter, the pulp was made into a an MFC by passing the carboxymethylated pulp at a concentration of 2 wt-% once through a high-pressure homogenizer (Microfluidizer M-110EH, Microfluidics Corp., USA) equipped with two differently sized chambers (diameter of 200 μm and 100 μm connected in series) with 170 MPa as the operating pressure. The formed MFC, which was a highly viscous gel, was diluted with deionized water to 0.56 wt-%, and was then dispersed with one pass through the high-pressure homogeniser in the same way as before. MFC/A-Starch Formulations Based on the concentrations of MFC and A-starch, blends of MFC and A-starch (50%:50%, mass ratio) were prepared in the following way: A composition of MFC and A-starch was passed once through a high-pressure homogenizer (Microfluidizer M-110EH, Microfluidics Corp., USA) equipped with two differently sized chambers (diameter of 200 μm and 100 μm connected in series) with 170 MPa operating pressure. After that, the composition was treated using an ultrasonic bath (Bransonic Ultrasonic Cleaner 5510E-MT, Bransonic Ultrasonics Corp., USA) for 10 minutes and was then placed on a vibrating table for 40 minutes to remove the entrapped air bubbles in the gel. Methods Hand-Sheets and Internal Treatments The freeze dried TMP pulp was, thawn and hot-disintegrated at 85-95° C. at 1200 rpm for 10 minutes in order to reduce the latency of the pulp. For the internal treatments, the pulp was treated with 1, 2 and 5% C-starch for 10 minutes before sheet-forming. When 5% C-starch was used 0.1% A-PAM was used as an adjuvant (complexing agent) to secure an almost quantitative C-Starch deposition onto the TMP-furnish. In this case the A-PAM was added 10 sec after the C-starch and then left 10 minutes before sheet-forming. Tap water was used and the pH was set to pH=8 Sheets with a basis weight of 100±2 g/m 2 were made in the Formette Dynamique Sheet former (CTP, Grenoble, France) (Sauret et al. 1969). The sheets were pressed together with blotters at 8.1 kg/cm 2 for 5.5 minutes, then the blotters were replaced with new ones and the sheet was pressed at the same pressure for 2 minutes more. The drying of the sheets was performed against a hot gloss Photo-dryer. Surface Treatments The surface sizing was done with a bench coater (KCC coater M202, RK Print-coat Instruments Ltd., UK) equipped with wire-wound rods. Sizing was performed at a speed of the moving rod of approx. 5 m/min. The surface sizing operation was performed on the top side only on the Formette Dynamique sheets and along the MD direction. The sheets were pre-dried at room temperature until the tackiness disappeared and finally dried against a hot gloss Photo-dryer. All surface sized sheets were dried for the same time. Repeated and parallel surface sizing operations were carried out. The basis weight of the paper was 100 g/m 2 , while the coat weight was varied up to 5 g/m 2 . The following chemicals were surface sized: A-starch, MFC and 50/50 weight-% A-starch/MFC composition. In the experiments, at least 3 different surface sizing levels were used. All samples, including blank or reference sheets making, sheets by internal treatments and sheets by surface treatments, were prepared according to the matrix shown in Table 1. TABLE 1 Experimental matrix Internal treatment TMP TMP (1% TMP (2% (without C-starch + C-starch + TMP Coating any 0.1% A- 0.1% A- (5% C-starch + Chemical chemicals) PAM) PAM) 0.1% A-PAM) Reference * * * * A-starch * * * * MFC * * * * A-starch + MFC * * * * Calendaring Pre-Calendaring All sheets were pre-calendered in a soft nip laboratory calender (DT Laboratory Calender, DT Paper Science Oy, Finland), under a line pressure of 16 kN/m at a roll temperature of 22° C. for one time. Thereafter, the sheets were calendered twice on each side of the sheets, which gave a Bendtsen surface roughness around 200±50 ml/min (see below). This is a normal value for commercial newsprint sheets. Post-Calendaring The surface sized sheets were also calendered after the surface sizing treatment. Firstly, the surface sized sheets were conditioned according to the standard method SCAN-P 2:75 (Scandinavian Pulp, Paper and Board Testing Committee) for at least 48 hours. The sheets were then calendered once in the soft nip laboratory calender under a line pressure of 12 kN/m at a roll temperature of 22° C. before further surface analysis and printing tests were performed. Analysis Grammage and Surface Roughness Grammage and weight of coating layer was determined according to standard method SCAN-P 6:75 (Scandinavian Pulp, Paper and Board Testing Committee). The Bendtsen method (ISO 8791-2) was used for the determination and control of surface roughness. Linting tendency-Lint Pick Test In this method, developed at STFI-Packforsk AB, Sweden, a paper sample is placed on an IGT-printability tester and the steel disc, made sticky with a thin film of pick-test oil is pressed against the paper. A print is then made at an accelerating speed. The disc is then photographed with a CCD-camera in a stereomicroscope. The disc is divided into 20 segments, which correspond to each photo taken by the camera. Since the acceleration is not linear, the four first and the two last segments on the disc were left out of the analysis. Hence, the measurements are performed on segments 5-18. The photos from these segments are analyzed and the amount of particles present (particles that have been removed from the surface of the sheets) is counted (particles/cm 2 ). The result is a number of particles, which have been shed from the surface at a specific speed. The particle counting was performed using an image analysis software (Linting Large Part, STFI-Packforsk AB, Sweden). This software distinguishes between four different groups of particles in the images: fibres, clusters, particles and small particles. The criteria for the groups are: Fibre: The object's circumference is >2 mm and its rectangularity is <0.3 i.e. the object is long. Cluster: The object's area is >0.3 mm2 or its circumference is >2 mm and its rectangularity is >0.3. Particle: The object's area is 0.02-0.3 mm2. Small particle: If none of the above, the object is a small particle. The LPT-measurements in this work were based on the IGT pick resistance method (ISO 3783) using an IGT-printability tester (IGT AIC 2-5, Reprotest b.v., The Netherlands). The steel disc was made sticky using 13.7±1.1 mg of pick-test oil (IGT Pick Test Oil (404.004.020) middle viscosity, Paper Test Equipment, Sweden). Instead of detecting the start of the pick on the test strip, the particles picked up on the print disc were detected using a CCD-camera (Model ICD 700, Ikegami, Japan, used resolution=15 μm/pixel) connected to a stereomicroscope (Model SZ-CTV, Olympus Sverige AB, Sweden). The maximum print speed measured was 5.0 m/s. The Fibre Rising Tester is a method developed by STFI-Packforsk in the beginning of the 1990's (Hoc 2005). Fibre rising tendency (FRT) is defined as the amount and the size of fibres that rises from the paper surface when the paper is wetted, dried and then transported over a thin roll. This method gives information of how the bonds between the surface fibres can resist wet induced fibre rising. It is also possible to measure the dry dusting by just turning the wetting procedure off. The principle is that a paper sample is wetted with a certain amount of water and is then dried with IR-heating element. The amount of fibre rising and roughness is continuously registered by a CCD-camera as the sample is being bent over a thin roll. Dampening Drying Recording Image Analysis When the paper is exposed to moisture and heat, different types of structural changes may occur on the surface. The FRT evaluates the sample based on two types of changes, referred to as Long Fibre Rising and Short Fibre Rising. Long fibres are bonded only at one end and extend more than 0.1 mm above the surface, while the short fibres are bonded along most of their length and extend no more than 0.1 mm above the surface. It is the long fibres that can cause linting problems due to their relatively long free ends and they are expressed as total length in millimetres. Changes in the surface structure appear when the fibre network of the paper in the surface comes into contact with water and heat. These changes give rise to two separate effects, roughening and fibre rising. Both these effects can be described by the measurement of four parameters: LRC (Long Rising Component) is a parameter, which describes the extent of the fibre rising as the total measured length of all fibres which rise from the paper surface after the surface treatment. SRA (Short Rising Area) is a parameter, which describes the increase in surface roughness (roughening) as the measurement of the total area of all the particles which have been lifted from the paper surface but cannot be identified as fibres since the height of each of these particles is less than 0.1 mm. TRA (Total Rising Area) is a parameter, which is defined as the total area of all the raised fibres including the area of all the particles which have been lifted from the paper surface but which are not fibres. Q (Fibre Quantity) is the number of identified fibres, i.e. the particles whose length is greater than 0.1 mm. In this work, the samples were cut in 4.0 cm wide and at least 10 cm long strips. Ordinary copy paper was taped to the ends of the strips to make the test more material efficient (the FRT needed a longer sample than the area it actually needed for performing the test). The sample was placed in the FRT (FIBRO 1000, Fibro system AB, Sweden) and tested in the machine direction (MD). The sample was wetted with 6.0 g/m 2 of water. After that the paper was dried using IR-heating element until the paper surface had a temperature of 110° C. The sample was then transported over the thin roller and a CCD-camera registered rising fibres and roughness. In total 100 images were analysed by the equipment. Three specimens per sheet sample were measured. Oil Absorbency To estimate the ink absorbency for sheets, contact angle measurements were performed using a Dynamic Angle Tester (DAT 1100, Fibro system AB, Sweden). The measurements were performed by dropping a drop of castor oil (Castor oil USP, density=0.96 g/cm 3 , Sigma-Aldrich Inc., USA) on the top side of the sheets. The initial drop volume was 7.0 μL and the change in drop volume over time (time span 0-12 s), drop base diameter and contact angle was measured. For each sheet sample, 8 parallel paper strips were measured (8 drops/paper strip) to get an average value. Environmental Scanning Electron Microscope-Field Emission Gun (ESEM-FEG) ESEM micrographs of sheet surfaces and cross-sections were taken to study the surface morphology and the layer structure of the sheets. The ESEM-micrographs were captured using ESEM model XL30 ESEM-FEG (Environmental Scanning Electron Microscope-Field Emission Gun) from Philips, The Netherlands. The working conditions were as follows: accelerating voltage=10 kV, WD=9 mm (working distance), low vacuum mode with BSE detector (backscattered electrons), and pressure in sample chamber=0.1 kPa. ESEM micrographs of the paper surfaces were also taken in high vacuum mode using SE detector (Secondary Electrons) at the same accelerating voltage 10 kV. WD was somewhat shorter ca 8.5 mm. For high vacuum mode the sheet surfaces were coated with a thin conducting layer of gold to prevent charging. ESEM micrographs of the cross-sections, giving z-direction information about the sheet structure, were obtained from the embedded papers. The paper samples were embedded in epoxy resin Spurr, grounded and then polished to obtain a smooth surface. Results Linting Tendency Analysis Compared with the conventional IGT pick resistance method, according to which the start of the pick on the test strip is recorded, the particles picked up on the print disc were evaluated with image analysis regarding the area coverage, number and size classification in the STFI-LPT method. Furthermore, LPT describes the tendency of a paper to shed particles as a function of printing speed. Hence, the results of the LPT are believed to be a good quantification of the linting tendency. To simplify the analysis result, the area coverage of particles picked up in the LPT-results as a function of print speed is discussed in the following. Linting Tendency of the Sheets with Internal Sizing Treatments The TMP sheets were made with a reference sheet and with the addition of C-starch (1%, 2% and 5% C-starch+0.1% A-PAM) to the wet stock. A-PAM was used as a co-additive in order to retain the non-adsorbed extraneous C-starch at the highest addition level. Basically, the retention of C-starch to the fibres was quantitative. The LPT results from these internally sized sheets are displayed in FIG. 1 . It was clearly observed that, at the same linting tendency, the print speed could be increased with the addition of C-starch. In other words, the surface strength of the sheets was increased by the addition of C-starch. An excess of more than 1% C-starch was, however, necessary in order to significantly improve the linting tendency of the TMP sheets. Linting Tendency of the Sheets with Different Surface Treatments In FIG. 2 , a reference sheet (internally sized with 2% C-starch) was surface sized with A-starch, MFC, and a mixture of MFC with A-starch (50%:50%, mass ratio), respectively, at a similar addition level. From FIG. 2 it is clear that both surface sizing with A-starch and MFC effectively reduces the linting tendency of the sheets. Secondly, there is also shown that there is a synergistic effect of adding both MFC and A-starch to the surface of the papers. FIG. 3 displays a similar series of experiments, where a reference sheet (internal sized with 5% C-starch) was surface sized using A-starch, MFC, and a mixture of MFC with A-starch (50%:50%, mass ratio) at similar addition levels. In this series of experiments an important observation was made. Despite the covering of the paper surface with a continuous MFC film, the sheet coated using MFC was easily delaminated when exceeding a certain critical printing speed. When the print disc was examined (see FIGS. 7 and 8 ) it was observed that the print disc was cleaner prior to delamination and that when the sheet was delaminated chunks of debris (film plus debris) was found. The MFC has a very high water retention capacity, hence it will not penetrate the sheet and a weak zone is formed at the interface between the MFC-film and the paper surface. This explains the synergistic role of using MFC and A-starch together. The A-starch will simply enhance the interface between the MFC-film and the paper surface, strongly decreasing the linting propensity of the sheet. Several series of experiments with different levels of internal and surface sizing additions using MFC, A-starch and C-starch using TMP were then exercised. In order to correct for slightly different addition levels in the various experiments a software (DataFit 7.0) was used to calculate the interpolated values at the addition levels of 1, 2 and 5%. The results so obtained are displayed in FIGS. 9 , 10 and 11 . Hence, FIG. 6 displays the effects of 1% internal C-starch addition and 1% surface addition of MFC, A-starch and a mixture of MFC/A-starch (50/50%). The effect of the internal addition of C-starch was again small, whereas both A-starch and MFC gave significant reductions in linting tendency. The synergism of adding a mixture of A-starch and MFC was again clear. FIG. 7 displays the results with an addition of 2% and the results are essentially similar to those in FIG. 8 , but the surface strength of the sheets are, of course, stronger. The Effects of Internal and Surface Sizing on Oil Absorbency of TMP-Sheets A surface treatment of a newsprint sheet may jeopardize the ink absorbency of the sheet, resulting in ink set off and slow drying of the ink. Therefore, treated sheets were tested with respect to the oil absorbency after internal or surface sizing treatments. In the oil absorbency test the volume of an oil drop on the surface of a paper sheet is recorded versus time and typical results are displayed in FIG. 8 . The data were also displayed as a decrease of the oil drop vs. time as displayed in FIG. 9 . Both an internal sizing treatment and a surface treatment results in a slightly lower oil absorption. Surface treatments results in a barrier type retarded absorption, whereas an internal treatment results in a more consolidated sheet resulting in retardation of the oil absorbency. However, in comparison with the blank sheet, the decreasing tendency of oil absorption is limited. Application Test on a Commercial Newsprint Sheet The Formette Dynamique laboratory paper sheets used in the previous part of the report, are characterized as having superior formation characteristics and in one series of experiments, commercial newsprint was also coated with MFC for comparison. The results are shown in FIG. 10 . MFC-coatings alleviate the linting propensity for commercial newsprint sheets just as for the laboratory sheets. The oil absorption was also investigated. All these experiments demonstrate the efficiency of MFC to reinforce the surface characteristics of a commercial newsprint sheet. Fibre Rising Tendency of Commercial Newsprint Using MFC Surface Treatments Fibre rising is defined as the amount and the size of fibres that rise from the paper surface when the sheet is wetted, dried and then transported over a thin roller. The commercial newsprint was surface treated with MFC and the results of FRT are shown in the following FIG. 11 . FIG. 11 shows that the long fibre rising content (LRC) was decreased after the MFC surface treatment. However, the short fibre rising area (SRA) and total fibre rising area (TRA) were decreased firstly but increased when the amount of coating MFC exceeded a certain point ESEM Analysis Examples of ESEM images of starch, MFC and MFC/starch coated sheets illustrate an appearance of both sheet surfaces ( FIGS. 16 a - d ) and cross-sections ( FIGS. 17 a - d ). As can be seen on the reference sheet before coating ( FIG. 12 a ) the surface is fairly rough. The coating results in a smoother surface ( FIGS. 16 b - d ). The MFC coating results a smoother surface than the A-starch. This probably is a result of a better film forming for the MFC. This difference can also be seen in cross section images if FIG. 13 b (A-starch) is compared to FIG. 13 c (MFC). The MFC seems to form a relatively thick film that lays on top of the sheet surface while the A-starch forms a thinner film which also penetrates into the sheet in a different way. As was disclosed above, the weakness of the MFC film is that it seems to be less anchored to the sheet which causes delamination between the MFC layer and the sheet (see FIG. 5 ). The weakness with the A-starch is instead that it is not as effective in decreasing the linting. This might be due to the poorer film forming by the A-starch seen in FIG. 13 b . By combining A-starch and MFC it is still possible to form a film on top of the sheet (see FIG. 13 d ). This film is probably mainly composed of MFC. The A-starch, can instead penetrate into the sheet in a better way. Based on the linting results shown above, one could speculate that a combination of MFC and A-starch is beneficial since it offers a possibility to both coat the sheet with a film that holds the linting particles in place as well as partially anchoring the particles internally in the sheet as well as anchoring the MFC film to the sheet. Advantages of the Invention The linting tendency of newspaper can be alleviated via surface sizing treatments with MFC, starch or a mixture of the two additives. Compared with merely internal treatment with C-starch, the surface treatment is more efficient in decreasing linting tendency. The MFC gel does not penetrate easily into the base sheet due to its high water retention capacity. Therefore, a sheet coated with MFC may delaminate at higher printing speeds than a sheet coated with A-starch or MFC+A-starch. It was found that there is a synergism in using a mixture of MFC and A-starch, which decreased the linting propensity more than the application of either MFC or A-starch. A-starch functions to reinforce the phase boundary between the MFC and the base sheet. It was also found that the long fibre rising tendency strongly decreased with MFC surface applications. Oil absorbency was found to decrease somewhat with increasing amount of coating chemicals.

4y

CROSS REFERENCE TO RELATED APPLICATION This is a continuation-in-part of co-pending application Ser. No. 840,434, filed Mar. 14, 1986, now abandoned. TECHNICAL FIELD The present invention relates generally to fluid filters of the spin-on type. More particularly, this invention concerns a reinforced spin-on filter incorporating a rigid, unitary cover which is connected to the housing by means of an inwardly folded lip that engages ribs on the end of the cover to secure the cover and housing against both separation and rotation in a manner which improves fatigue strength. BACKGROUND ART Spin-on filters have been employed heretofore in a variety of applications including hydraulic systems and engine lubrication systems. Such filters generally include a filter element within a can or housing having a cover or attachment plate at one end thereof by which the filter can be screwed onto or off of a filter head. A central opening and several surrounding openings in the cover direct fluid flow through the filter, which flow can be in either an inside/out or outside/in direction relative to the filter element. A circular gasket on the outside of the cover serves as the external seal between the filter and the filter head, while another circular gasket on the inside of the cover functions as the internal seal between the filter element and cover. A spring is often provided in the lower end of the housing to maintain the filter element in sealing engagement with the cover. Spin-on filters are usually intended to be used only once before removal and replacement. Although satisfactory in low- and medium-pressure applications, most spin-on filters of the prior art have not been particularly suitable for use in high-pressure applications, such as in hydraulic transmission pumps, where spikes or surges up to about 1,000 psi can occur. Many of the spin-on filters currently available are adaptations of the type used in engine lubrication systems. The covers of such spin-on filters are typically constructed of a stamped steel-based disc and a relatively thinner secondary disc spot welded thereto. The base disc includes an extruded, relatively shallow, internally threaded neck portion by which the filter can be connected to a filter head. Flow openings are punched into the base disc around the neck portion. The lip at the open end of the housing is connected by means of a lock seam to the periphery of the secondary disc, which is also formed to serve as a seat for the external gasket. In spin-on filters of this type, any fatigue failure is most likely to occur at the rolled lock seam or at the spot welds. Any burst failure is most likely to occur either upon bending of the cover, which allows leakage past the external gasket, or upon unfolding of the rolled lock seam. The prior spin-on filters of this type have thus been susceptible to failure at the cover and/or at the connection between the cover and the housing. Various attempts have been made to strengthen and otherwise increase the pressure capacities of the prior spin-on filters. Different materials and/or increased material thicknesses have been used, improved lock seams have been developed, and reinforcing profiles have been formed into the cover plates. These efforts have resulted in increasing the burst capacities of such spin-on filters up to about 500 psi, and have therefore been of some success; however, even filters of such capacity can be marginal in certain applications. In addition, reinforcing efforts of this type tend to increase the cost of such filters. It will be understood that manufacturing limitations and production economies can be important factors in the construction of such spin-on filters. More recently, U.S. Pat. No. 4,369,113 issued to Donaldson Company, Inc., for an improved high-strength spin-on filter which overcomes many of the disadvantages of the prior art. This spin-on filter is capable of withstanding pressure surges and spikes up to about 1,000 psi or more, and has met with considerable commercial success. While suitable for use in many high-pressure applications, however, it has been found that fatigue strength can be just as important as pressure capacity in certain applications, such as hydrostatic transmissions and charge pump circuits, involving cyclical operational loads. There is thus a need for an improved reinforced spin-on filter of high pressure capacity and better fatigue rating. SUMMARY OF INVENTION The present invention comprises an improved high-strength spin-on filter which overcomes the foregoing and other difficulties associated with the prior art. In accordance with invention, which is an improvement over the filter shown in U.S. Pat. No. 4,369,113, there is provided a high-strength spin-on filter comprising a generally cylindrical filter housing having open and closed ends. A generally cylindrical filter element is disposed within the housing. A cover is secured to the open end of the housing. The cover, which is preferably is of one-piece integral construction, includes a central hub and a plurality of radial ribs interconnecting the hub and a circular rim. The cover also includes flow openings that terminate on opposite sides of the filter element inside the housing. Gasket seats are formed in the outer end and the side surface of the rim of the cover. The open end of the housing is folded inwardly over the rim of the cover in a manner which approximates the effect of a flat bottom in a pressure vessel, whereby stresses are reacted in shear rather than bending. In particular, a plurality of radial teeth are provided about the outer end of the cover in a circular groove therein for direct engagement with the folded connection so as to constrain the cover and housing against both separation and rotation while avoiding points of stress concentration that would otherwise be susceptible to fatigue during use in high-pressure charging circuits and the like. BRIEF DESCRIPTION OF DRAWING A better understanding of the invention can be had by reference to the following Detailed Description in conjunction with the accompanying Drawing, wherein: FIG. 1 is a top view of a spin-on fluid filter incorporating a first embodiment of the invention; FIG. 2 is an enlarged axial section view taken along lines 2--2 of FIG. 1 in the direction of the arrows; FIGS. 3 and 4 are top and bottom views, respectively, of the cover of the spin-on fluid filter of the invention; FIG. 5 is an enlarged view of a portion of the spin-on fluid filter shown in FIG. 2; FIG. 6 is a cross-sectional view taken along 6--6 of FIG. 5 in the direction of the arrows showing the details of the cover/housing connection of the first embodiment; FIG. 7 is a top view of a spin-on filter incorporating a second embodiment of the invention; FIG. 8 is a top view of the cover of the filter shown in FIG. 7; FIG. 9 is an enlarged partial axial section view taken generally along lines 9--9 of FIG. 7 in the direction of the arrows; and FIG. 10 is an.enlarged partial cross-sectional view taken generally along lines 10--10 of FIG. 9 in the direction of the arrows showing the details of the cover/housing connection of the second embodiment. DETAILED DESCRIPTION Referring now to the Drawing, wherein like reference numerals designate like or corresponding elements throughout the views, and particularly referring to FIGS. 1 and 2, there is shown a spin-on fluid filter 10 incorporating a first embodiment of the invention. As will be explained more fully hereinafter, the filter 10 is particularly adapted for filtration of oil in hydrostatic transmissions and other systems characterized by cyclical high-pressure loads. The filter 10 incorporates several components which are substantially similar to the filter shown in my prior U.S. Pat. No. 4,369,113. For example, filter 10 includes a generally cylindrical filter housing 12 having an open top end 14 and a closed bottom end 16. The housing 12 is a generally thin-walled construction, and is typically formed by stamping or drawing from metal such as steel or other suitable material. For example, housing 12 can be formed from deep drawn steel of about 0.040-inch wall thickness. A filter element assembly 18 is positioned inside the filter chamber defined by housing 12. The filter element assembly 18 includes a perforated core 20 surrounded by a filter element 22, both of which are generally cylindrical and supported between a pair end pieces 24 and 26. The bottom end piece 26 extends across and closes the bottom end of the perforated core 20, which can be paper or other suitable media, while the upper end piece 24 includes a central opening for receiving a portion of a cover 28 secured within the open end 14 of the housing 12. The filter element 22 can be potted in place or otherwise secured between the end pieces 24 and 26 as shown. Standoff-spacers 29 are provided about the bottom end piece 26 for pressure equalization. The spacers 29, three of which can be utilized at equal circumferentially spaced intervals, are preferably formed integral with bottom end piece 26. The cover 28 includes a central hub 30 which is interconnected by a plurality of radial webs or ribs 32 with a circular outer rim 34. As illustrated, cover 28 includes six ribs 32 at equally spaced intervals, although the precise number of ribs and spacing therebetween are not critical to practice of the invention. The hub 30 defines an axial opening 36 extending through cover 28. Openings 38 are also defined in the cover 28 between hub 30, ribs 32 and rim 34. The openings 36 and 38 serve as flow ports whereby fluid to be filtered is circulated through filter 10 in either an inside/out or outside/in flow direction through the filter element assembly 18. Threads 40 are provided on the upper inside surface of the hub 30 for connecting the filter 10 to a filter head (not shown). The cover 20 is preferably formed by casting or the like from metal, such as aluminum, or other suitable material, into a rigid integral unit. Three seals are provided on the cover 28. A seal 42 is located on the inner end of the cover 28 between the hub 30 and the upper end of the filter assembly 18. Another seal 44 is located in a circumferential groove formed around the rim 34 between cover 28 and the upper end 14 of the housing 12. Yet another seal 46 is located in a groove on the outer end of the cover 28 surrounding openings 36 and 38 for external sealing purposes between the filter 10 and the filter head (not shown). The groove within seal 46 is seated preferably includes a plurality of radial projections 48, which are best seen in FIGS. 2 and 3, for releasably retaining the seal in place during handling of the filter 10. The cover 28 and housing 12 are secured together by a folded connection 50. In particular, cover 28 includes a peripheral lip 52 defining a groove in the outer end of the rim 34 surrounding the inner groove containing the O ring seal 46. A plurality of circumferentially spaced-apart, outwardly extending radial projections 54 are provided in the outer groove opposite lip 52. As illustrated, six projections 54 at equally spaced intervals have been used, although any suitable number can be utilized. The upper end 14 of housing 12 surrounds the rim 34 and extends inwardly over the lip 48, with the terminus of the upper end being folded inwardly and underneath itself in deforming engagement over projections 54 and behind the lip. A spinning operation is preferably utilized to accomplish folding. This particular connection between housing 12 and cover 28 comprises a critical feature of the present invention. Use of the folded connection 50 approaches the effect of a flatbottom pressure vessel, resulting in greater resistance to unrolling and straightening so that the stress is reacted more in shear than in bending whereby a higher pressure capacity can be achieved. As the folded connection 50 is formed, the folded terminus of the end 14 of housing 12 deforms over projections 54 so that the resultant folded connection serves to secure the housing 12 and cover 28 together against rotation as well as separation. The folded connection 50 thus serves two purposes and eliminates the need for extended ribs and corresponding indentations in the side of the housing, as in my prior filter, which secure the housing and cover against rotation, but which can also become areas of stress concentration that would otherwise be susceptible to fatigue failure in pulsating high-pressure hydraulic circuits. Preliminary test results have confirmed that this construction improves the fatigue life of the filter 10 about four to ten times over that of my prior filter. For example, direct comparison tests have been conducted between the improved filter herein and its predecessor shown in U.S. Pat. No. 4,369,113. The filters were of identical size and construction, except for the side versus end cover/housing interlock feature. The covers of both filters were of cast aluminum, and their housings were of 0.048 inch deep drawn mild steel. Both filters were subjected to cyclic pressure loads of 0 to 400 psi at 2 hertz or two times per second, under both sine wave and square wave loads. Under sine wave loads, the old filter failed after an average of 124,300 cycles, whereas the new filter failed after an average of 1,233,900 cycles, for an increased fatique life ratio or factor of about 9.9. Under square wave loads, the old filter failed after an average of 165,900 cycles, whereas the new filter failed after an average of 566,800 cycles, for an increased fatigue life factor of about 3.4. The overall average increased fatigue life factor of the new filter over the old filter for both sine and square wave loads during these tests was about 5.5. As for failure mode, the old filter failed when the housing cracked at the side rib/detent interlocks which, as explained above, are areas of stress concentration. The new filter failed when the cover cracked or when the housing cracked at its closed or "dome" end, confirming the structural superiority of the new filter. FIGS. 7-10 illustrate an improved spin-on fluid filter 60 incorporating a second embodiment of the invention. The filter 60 utilizes several components which are substantially identical in construction and function to components of the filter 10 herein. Such components have been identified with the same reference numerals utilized hereinbefore in conjunction with the description of filter 10, but have been differentiated therefrom by means of prime (') notations. The primary distinction between the spin-on filters of the two embodiments herein resides in the fact that filter 60 includes a plurality of inwardly extending radial projections 62 for interlock with the folded connection 50', instead of outwardly extending radial projections 54 of filter 10. As illustrated, the filter 60 includes twelve projections 62 at equally spaced intervals, although any suitable number can be utilized. The projections 62 are relatively smaller and more numerous than projections 54, but function in the same manner so that the folded connection 50' of the filter 60 interlocks the housing 12' and cover 28' against both rotation and separation. In all other respects, the filter 60 is structurally and functionally similar to filter 10. From the foregoing, it will thus be apparent that the present invention comprises an improved high-strength spin-on filter having several advantages over the prior art. Improved fatigue strength without additional parts, manufacturing steps and increased cost are but some of the advantages. Other advantages will be evident to those skilled in the art. Although particular embodiments of the invention have been illustrated in the accompanying Drawing and described in the foregoing Detailed Description, it will be understood that the invention is not limited only to the embodiments disclosed, but is intended to embrace any alternatives, equivalents, modifications and/or rearrangements of elements falling within the scope of the invention as defined by the following claims.

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RELATED U.S. APPLICATION DATA [0001] This application is a Continuation-in-Part of co-pending U.S. patent application Ser. No. 11/434,583, filed 10 May 2006. STATEMENT OF GOVERNMENT INTEREST [0002] The invention described herein may be manufactured and used by or for the Government of the United State of America for governmental purpose without payment of any royalties thereon or therefore. BACKGROUND OF THE INVENTION [0003] Most of the materials presently used to coat naval platforms and to encapsulate acoustic sensors have been around for decades. The performance of these materials from a variety of perspectives is truthfully characterized as “barely adequate.” Because of these limitations, design engineers have had to accept many compromises concerning cost and/or service lifetime. These compromises now threaten the viability of some of the U.S. Navy's most cherished future hardware concepts, such as miniaturized, distributed sensors, large area sensors smart skins, and hi-powered acoustic sources. They are also inconsistent with the Navy's current “total ownership cost reduction” thrusts in the areas of service lifetime extension and reduced maintenance requirements. Using existing materials alone many of these advanced concepts and reliability improvements simply cannot be realized. The existing materials are used because of their ease of application and because other concerns and material requirements (primarily acoustical) are viewed as more important than their barrier properties. [0004] The encapsulants used in acoustic applications must be acoustically clear. The term “acoustically clear” means that acoustic energy is able to enter and transit through the material with a minimal amount of reflection, loss, distortion or absorption. Only a small set of polymers have been found to possess the physical properties and chemical structures that ensure acoustic clarity. Of these materials, those that are castable, such as polyurethane, tend to exhibit greater water permeability than those that are vulcanizates, such as butyl rubber, EPDM (ethylene propylene diene monomer) rubber, and polychloroprene rubber. [0005] Castable materials are preferred because they can be poured into molds and cured at room temperature or at moderate temperatures in an oven. Commonly used acoustic devices include sensors and sources. These devices are made from materials such as piezoelectric crystals and polymers, are temperature sensitive, and cannot be subjected to high temperatures and pressures. The vulcanizates require higher temperatures and pressures to cure. Thus they are typically made in the form of a boot or covering that is then adhesively bonded or mechanically clamped to the acoustic device. Modification of castable, acoustically clear materials to make them less permeable to water is highly desirable. Any such modifications would have to preserve the superior acoustic properties of such materials while at the same time, greatly enhancing their barrier properties. [0006] Nanomaterials and polymer nanocomposite technology might be able to enhance current encapsulants. As its name implies, a nanocomposite contains particles with at least one nanoscale (10 −9 meter) aspect (length, width or thickness). Because of the enormous surface area a dispersion of such particulates possesses, relatively small loadings (typically a few weight percent) in a suitable polymer matrix may exhibit orders of magnitude-scale improvements in certain physical properties and/or influence the structure of the polymer matrix in ways not possible to achieve with conventional technology. Careful selection of the chemistry and geometry of the nanoparticles frequently allows the bulk properties of the resulting polymer nanocomposite to be close to those of the unfilled polymer matrix: while greatly enhancing a specifically targeted physical property of interest. Such “input/output” selectivity promises to deliver significantly improved coatings and encapsulants for naval applications including coatings with orders of magnitude lower water/gas permeability and encapsulants with ten times the normal polymer thermal conductivity. [0007] The barrier-property-enhancing fillers are nanoscale (ca. 3-10 nanometers thick by several hundred to several thousand nanometers across) plates derived from a variety of different phyllosilicate clay minerals, such as montmorillonite, hectorite, saponite, bentonite and the like. These materials are known as “sheet silicates” because they are made up of tiny particles which are themselves composed of a large number of extremely thin mineral sheets (like mica). Thousands of these individual sheets stacked on top of each other form an individual clay mineral particle. The sheets are only loosely held together in the vertical direction by Van der Waals forces. Thus, the particles are permeable in the X-Y direction (between sheers), but they are essentially impermeable in the Z direction (through the sheets). Clay minerals are preferred as starting materials because they are composed of nano-to-micron scale particles that can be converted (with the proper chemical pre-treatment) into large numbers of individual sheets/plates with large aspect ratios (typically 100:1 or greater). [0008] These fillers are not typically used in acoustic applications because they are not acoustically transparent. The speed of sound, c, in the composite is approximately equal to: [0000] c = M ρ ( 1 ) [0000] where: M=modulus of elasticity; and ρ=density. For acoustic clarity, the product of sound speed, c, and density, ρ, of the coating/encapsulant must be as close to the ρc product of the surrounding medium, seawater. Unfilled polyurethane has a ρc product approximately equal to that of seawater. Adding a filler of higher density, like clay, causes the ρc product of the resulting composite to deviate from the ρc product of seawater. The more filler, the higher the density. Also, as filler is added, the modulus increases, and thus, so does the sound speed, c. In conventional composites it is common to add 20-30% by weight of filler. This makes the composite material no longer acoustically transparent. Thus, the use of fillers in polyurethane has always presented a problem. [0009] There are three possible particle-matrix in clay particulate-based polymer nanocomposites shown in FIGS. 1A , 1 B and 1 C. First, in FIG. 1A , the composite 10 A is shown with the clay particles 12 dispersed within the polymer matrix 14 in their natural state. This geometry does not lead to especially interesting or useful properties because the clay particles 12 are porous and do not present an obstacle to liquid travel. FIG. 1B shows the “exfoliated” or “delaminated” geometry as 10 B. In this geometry, the individual sheets 16 comprising each clay particle are separated from each other and dispersed individually within the polymer matrix 14 . Sheets 16 are disposed randomly in the matrix. Because the individual sheets 16 are not overlapped, they do not present significant barriers to fluid travel. The third polymer-particulate geometry is shown in FIG. 1C . The geometry of sample 10 C is referred to as “intercalated.” In this arrangement, a single layer of polymer chains 18 is infiltrated between the individual sheets/layers 20 that comprise a clay particle. A polymer matrix 14 is formed outside of the intercalated particles. This geometry leads to alternating, thin layers of silicate and polymer a few nanometers apart. [0010] Both the exfoliated and the intercalated geometries lead to improvements in the barrier properties (including a significant decrease in water permeability) of the resulting nanocomposite; however, the intercalated geometry leads to significantly better properties. The primary difference between creation of the geometries is the time and extent of mixing or sonicating. As mixing increases, the clay particles become delaminated and are more likely to form the exfoliated geometry. [0011] For applications in which water permeation is a critical concern, hydrophobic, non-polar polymers such as EPDM and butyl rubber are typically used. These materials are vulcanizates which are crosslinked through the use of heat in pressurized molds. These materials must be molded first, and then bonded to the sensor. Their non-polar nature makes it difficult to bond anything else strongly to them. Thus, most EPDM and butyl rubber boots are secured to the underlying sensor (where possible) by metal bands or other mechanical means. What marine sensor designers would really like to have is an acoustically “clear” encapsulants that will cure in place where it is poured, and which, when cured, will exhibit very low water permeability constants similar to (or better than) those of EPDM and butyl rubber. At the present time, no such materials exist. SUMMARY OF THE INVENTION [0012] Accordingly, this invention is an acoustically transparent low water permeability encapsulant made from an acoustically clear polymer such as polyurethane. High aspect ratio clay nanoparticles are positioned in the substrate in overlapping layers with layers of the substrate interposed. The invention also provides a method for forming an acoustically transparent castable low permeability encapsulant. The method includes treating high aspect ratio clay nanoparticles to make them organophilic. The treated nanoparticles are then mixed in a polymer resin. A curing agent is added to the mixture, and the mixture is allowed to set. [0013] These and other features, aspects and advantages of the present invention will become better understood with reference to the following drawings, description and claims. BRIEF DESCRIPTION OF THE DRAWINGS [0014] FIG. 1A illustrates a conventional mix of clay nanoparticles in a polymer matrix; [0015] FIG. 1B illustrates a delaminated mix of clay nanoparticles in a polymer matrix; [0016] FIG. 1C illustrates an intercalated mix of clay nanoparticles and polymer in a polymer matrix; and [0017] FIG. 2 is a cross-sectional view of an encapsulated acoustic device. DETAILED DESCRIPTION OF THE INVENTION [0018] The present invention utilizes chemically modified clay nanoparticles to significantly lower water permeation through acoustically clear polyurethane. The use of nanoparticle clay fillers allows avoidance of filler/acoustic clarity problems. This is because the amount of filler needed to achieve a large decrease in permeability is low, ca. 2-8%. This minimizes the change in density, ρ, and sound speed, c. [0019] In order to form an intercalated nanocomposite, the appropriate particles must be selected. The particles should be stacks of particles having a mean diameter at least 100 times the mean thickness. In other words, preferably, the aspect ratio should be greater than 100. An intercalated dispersion of the particles must be achieved. The polymer can then be allowed to polymerize between the plate-like particles to form a nanocomposite that functions as a permeation barrier similar to a tile roof on a building. The intercalated geometry is essential for proper functioning of the nanocomposite. If the particulates are too thoroughly dispersed or poorly dispersed, the scientific literature indicates that the desired decrease in permeability will not be realized. [0020] A considerable advantage of nanocomposites over traditional composites is that the large improvements in physical properties are achieved with relatively low filler loading levels. In some applications filler content is not a concern, but for acoustics, it is very important. As inorganic fillers such as clay particles are added to a polymer; two critical variables, density and sound speed, will increase, and the composite's acoustic clarity will degrade as a result. Because of this, nanocomposites are intriguing for use as sensor encapsulants not only because of the great decrease in water permeability that may be realized, but also because these physical property enhancements occur at low filler levels (about 5% by weight). Thus, for the first time, it should be possible to make ultra-low permeability and acoustically clear composites. [0021] In order to make these kinds of nanocomposites, it is necessary to chemically modify the clay particulates. For charge balance, clay minerals typically contain cations such as Na + , Li + and Ca 2+ between the individual sheets. Chemical pretreatment is necessary to convert these normally hydrophilic silicate surfaces into organophilic surfaces that are compatible with polymers. Suitable pretreatments include ion-exchange reactions with organic cations (typically alkylammonium ions), or alteration with silanes. [0022] The weight percentage of particles to polymer must be sufficient to provide barrier protection, but not so much as to interfere with the mechanical properties of the polymer. An ideal range of particle to polymer weight percentages is expected to be around 2-8%. At this weight percentage the resulting material has essentially the same acoustic characteristics as the polymer without the particles. (The addition of these particles may reduce permeability by a factor of 100.) Above this range, the material properties, including the acoustic properties decline. About 10% would be the maximum amount of particles for use in acoustic applications. Below 2%, the particles offer an insufficient barrier to permeating gasses or fluids. [0023] The polymer resin is preferably a polyurethane resin having good acoustic properties. It has been found that the commercially available polyurethane resin Uralite FH-3140 manufactured by H.B. Fuller has acceptable acoustic properties. This resin is used with the standard diamine curing agent. Other polyurethane resins and curing agents having “acoustically clear” properties are expected to be acceptable, as well. [0024] Once the clay particulates have been chemically pretreated, they are mixed into the polymer resin. The polymer resin infiltrates between the individual layers. A curing agent is added to the polymer resin mixture, and it polymerizes in situ. If the proper density of sheets/plates is achieved, the individual sheets will overlap each other, and the layers will function in a manner akin to shingles or tiles on a building roof. [0025] Solution and melt intercalation methods can also be used to form the intercalated polymer. In the solution method the treated nanoparticles are placed in a polar organic solvent having the polymer dissolved therein. The solvent is allowed to evaporate leaving the polymer disposed between layers of the nanoparticles leaving a polymer composite having intercalated nanoparticles. In the melt intercalation method, treated nanoparticles are mixed into a molten thermoplastic. The molten thermoplastic is poured into place and allowed to cool resulting in a solid composite having intercalated nanoparticles. [0026] Permeating molecules cannot pass through the sheets, and will need to spend a considerable amount of time moving mound each sheet to reach the next polymer-sheet layer, etc. Thus, permeation though such a coating is greatly retarded, and might be so slow that it could be considered to be negligible during the planned lifetime of the underlying sensor. The development of specially-modified clay nanoparticulates/polyurethane composites with good acoustic characteristics is critical for the manufacture of miniaturized distributed sensors. Fick's first law is an important component of permeation theory: [0000] J = - D  ∂ c ∂ z ( 2 ) [0027] In this equation, “J” is the flux of the permeating material; “D” is the diffusion coefficient; “c” is the concentration of the permeable material; and “z” is the thickness of the barrier coating. The flux of the permeating material, J, can also be expressed as a function of permeability: [0000] J = DS  ( p h - p l ) z ( 3 ) [0028] In this equation, S is the sorption coefficient, p h is the partial pressure of the diffusing species at the leading edge; p l is the partial pressure of the diffusing species at the trailing edge: and “DS” is the permeability coefficient. The above expressions for flux indicate that J and z are inversely related. Thus, if everything else remains the same, a reduction in z will result in an increase in the flux of permeating water, thereby shortening the useful working life of the coated device if conventional encapsulants are used. The introduction of clay nanoparticulates into a polymer reduces the flux of permeating water by lowering the diffusion constant, D. [0029] The addition of the modified clay nanoparticles has been shown to reduce permeability (DS) by at least an order of magnitude and possibly by several orders of magnitude in some polymers. If permeability were to be reduced by a factor of 100 by this method, then the thickness of the nanocomposite encapsulant layer could be reduced by the same factor while maintaining the same level of protection for the underlying sensor. If the thickness of the nanocomposite encapsulant layer were reduced only by a factor of 10, then the level of protection for the underlying sensor would be ten times greater than what is possible with existing, unmodified encapsulants, and one would expect the sensor to function in the marine environment ten times longer than normal. [0030] A reduction in encapsulant thickness without a corresponding loss of protection is desirable by itself, because polymeric coatings, by their very nature, increase the volume and mass of the sensor, and also exhibit non-zero acoustic attenuation values. The thicker the encapsulant layer, the greater the amount of acoustic attenuation. Attenuation disperses acoustic energy throughout the polymer as heat, and it can hamper or even prevent the detection of very weak, low-energy signals. Thus, sensor designers would prefer to use the thinnest possible encapsulant layer that will still protect the underlying electronics for the desired period of time. The development of polymer-clay nanocomposites should enable a considerable reduction in encapsulant thickness (and a corresponding increase in acoustic sensitivity) without any decrease in performance or service life. [0031] Significant improvements in barrier coatings would yield additional benefits to naval hardware. Many marine components that include metal to polymer bonds fail because of a process known as “cathodic delamination.” During cathodic delamination water and dissolved oxygen permeate through a protective polymeric coating (encapsulant, paint, etc.) and reach an underlying, cathodically polarized metal surface. At the polymer-metal interface, a reaction occurs that generates hydroxide ions from the water and oxygen and free electrons in the metal. An osmotic potential is set up between the bond-line region and seawater that results in the formation of pressurized water blisters that debond the polymer from the metal surface. In some cases, the hydroxide ions might also directly attack the metal-polymer bond. Coatings with greatly improved barrier properties could prevent, or at least significantly slow down, the cathodic delamination process, thereby extending the usable service lifetimes of many pieces of naval hardware. The potential savings in maintenance and replacement costs are considerable. [0032] In FIG. 2 , there is shown a device 22 having a low permeability encapsulant 24 formed thereabout. The device 22 can be any kind of acoustic device known in the art. These devices include transducers, accelerometers, piezoelectric crystals, piezoelectric composites, fiber optic devices and the like. A communications path 26 extends from the device 22 . The encapsulant 24 is cast around the device 22 and communication path 26 according to well known methods. Nanoparticles 28 are shown in the encapsulant 24 . This drawing is not to scale. With the methods taught herein, the encapsulant 24 can be thinner than previously known encapsulants while having the same or lower water permeability. [0033] It should be understood, of course, that the foregoing relates to preferred embodiments of the invention and that modifications may be made without departing from the spirit and scope of the invention as set forth in the following claims.

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[0001] This application claims benefit of Serial No. 98/MUM/2012, filed 11 Jan. 2012 in India and which application is incorporated herein by reference. To the extent appropriate, a claim of priority is made to the above disclosed application. FIELD OF THE INVENTION [0002] The present invention relates to an electrical vehicle battery packaging and more particularly to a swappable battery packaging offering a structural rigidity to the vehicle. BACKGROUND OF THE INVENTION [0003] The concept of the electric/hybrid vehicle is highly researched subject matter in an automobile field. The electric/hybrid vehicle produces zero emission of carbon as it requires energy produced by the battery modules for propulsion. [0004] Battery modules disposed in the electric vehicle provide power to the vehicle. The power of the vehicle can be increased by introducing more number of battery modules to the vehicle. [0005] Conventionally, all electric vehicles require a large battery module. In the current battery technology the pack occupies a significant portion of the total vehicle mass and requires substantial volume as well. In addition, such structured battery pack has limited life constraint by capacity and weight of battery packs. [0006] For recharging the battery, the driver has to halt the vehicle at several charging stations. Thus more time is wasted each time for recharging or driver has to swap for a fresh battery. [0007] Swapping of conventional battery module arrangement is not easy as the battery module is not standardized due to its shape, weight and capacity. Therefore, swapping of battery modules is a time consuming and cumbersome task. One such system for swappable battery pack for electric vehicle is disclosed in the US patent application number 20100181129 by Vahid Hamidi, which discloses a swappable feature of a battery pack, constraining to swapping of each individual battery modules only, and not to a complete battery pack. [0008] Thus, from users' perspective one who may not be necessarily proficient enough to repair the battery, replacing an individual battery module from the battery pack is complex task. Further, during displacement of the entire battery, the disassembly of electric connections, outer case and linear actuators in the vehicle is difficult and time consuming task. Furthermore, the battery packs disclosed hitherto, believed to force augmentation structural instability and blemish the ruggedness of the vehicle body. [0009] Thus, there exists a need for providing swappable battery to address the long-standing problem of swappable battery packaging system that is further adapted to provide a structural rigidity to the vehicle architecture resulting in an overall mass optimization. OBJECTS OF THE INVENTION [0010] The principal object of the present invention is to provide a swappable and configurable battery pack structure for an electric vehicle. [0011] It is another object of this invention to offer a self-repairable battery packing system, to even a novice user thereof, offering each of replacement or recharging operations. [0012] It is another object of the present invention to provide a battery pack that contributes to the structural rigidity of the vehicle allowing for overall mass optimization. [0013] It is another object of this invention to provide a battery package designed to support multiple configurations of batteries allowing for desired variable capacity. [0014] It is another object of this invention to provide a battery package comprising a plurality of cooling ports for cooling an interior ambient of the battery pack. [0015] It is yet another object of this invention to secure a battery packs in defined position via a securing means such that the securing means is adapted to prevent the batteries from loose connections that would result in loss of power. [0016] Further objects and advantages of this invention will become apparent from consideration of the drawings and descriptions that follow. SUMMARY OF THE INVENTION [0017] Before the assembly, components and methods are described, it is to be understood that this invention is not limited to the particular assembly and methods described, as there can be multiple possible embodiments of the present invention, which are not expressly defined in the present disclosure. It is also to be understood that the terminology used in the description is for the purpose of describing the particular versions or embodiments only, and is not intended to limit the scope of the present invention which will be limited only by the appended claims. [0018] In one aspect of the invention, an apparatus for battery packaging for an electric vehicle is provided , the apparatus comprising a plurality of battery modules, each of the battery module having a first electrical receptacle at bottom thereof; an housing commensurating with geometry of the battery module, the housing is adapted to compactly accommodate the plurality of battery modules; an internal base surface of the housing covered with an electro-mechanical insulator and a pair of bus bar mounted thereon, the electro-mechanical insulator, is adapted to extend an electrical contacts to the first electrical receptacles of each of the battery module; a plurality of interlocking blocks affixed at an outer surface of at least one face of the housing, each block having a hole on the surface thereof; a plurality of locator pin disposed on an adjoining vertical surface of the vehicle, each of the locator pin is adapted to mechanically secure a corresponding interlocking block; a slidable racket beneath the interlocking blocks comprising plurality of alternately placed slidable depressions to lock the interlocking blocks there within; and a second electrical receptacle extending there from at least one surface of the housing for establishing an electrical connection with the corresponding electrical contacts of the vehicle. [0019] In one aspect of the invention, a method for swappable battery package for an electric vehicle is provided, the battery package disposed within a housing, the method comprises: configuring a plurality of battery modules within the housing; coating an internal base surface of the housing with an electro-mechanical insulator and a pair of bus bar mounted thereon; affixing a plurality of interlocking blocks at an outer surface of at least one face of the housing, each block having a hole on a surface thereof; disposing a plurality of locator pins on an adjoining vertical surface of the vehicle, disposing a slidable ratchet beneath the interlocking blocks comprising plurality of alternately placed slidable depressions to lock the interlocking blocks therewith in; and disposing a second electrical receptacle extending there from at least one surface of the housing for establishing an electrical connection with corresponding electrical contacts of the vehicle. BRIEF DESCRIPTION OF DRAWINGS [0020] The foregoing summary, as well as the following detailed description of preferred embodiments, is better understood when read in conjunction with the appended drawings. For the purpose of illustrating the invention, there is shown in the drawings example constructions of the invention. However, the invention is not limited to the specific assembly and methods disclosed in the drawings. The present invention will now be described with reference to the accompanying drawing, in which: [0021] FIG. 1 illustrates an apparatus for a battery packaging for an electric vehicle. [0022] FIG. 2 illustrates an outer, inner base surface of housing with lid according to one exemplary embodiment of the invention. [0023] FIG. 3 illustrates battery housing disposed with the battery module according to one exemplary embodiment of the invention. [0024] FIG. 4 illustrates positioning of an electro-mechanical insulator according to one exemplary embodiment of the invention. [0025] FIG. 5 illustrates a mechanism of battery pack located to the vehicle structure according to one exemplary embodiment of the invention. [0026] FIG. 6 illustrates one possible configuration for air cooling of the battery. [0027] FIG. 7 illustrates battery pack configured for alternative capacity by varying the amount of modules in the pack. [0028] FIG. 8 illustrates an example for an integral battery apparatus contributing to overall vehicle structure. DETAILED DESCRIPTION OF THE INVENTION [0029] Some embodiments of this invention, illustrating all its features, will now be discussed in detail. The words “comprising,” “having,” “containing,” and “including,” and other forms thereof, are intended to be equivalent in meaning and be open ended in that an item or items following any one of these words is not meant to be an exhaustive listing of such item or items, or meant to be limited to only the listed item or items. It must also be noted that as used herein and in the appended claims, the singular forms “a,” “an,” and “the” include plural references unless the context clearly dictates otherwise. Although any assemblies and methods similar or equivalent to those described herein can be used in the practice or testing of embodiments of the present invention, the preferred, systems, assemblies and methods are now described. The disclosed embodiments are merely exemplary of the invention, which may be embodied in various forms. [0030] The present invention provides an apparatus and a method for battery packaging for an electric vehicle. The battery packaging apparatus comprises a plurality of battery modules where each of the battery module having a first electrical receptacles at bottom thereof. The battery packaging apparatus further comprises an housing commensurating with a geometry of the battery module wherein the housing is adapted to compactly accommodate the plurality of battery modules. The housing comprises an internal base surface of the housing covered with an electro-mechanical insulator and a pair of bus bar mounted thereon. Further, the electro-mechanical insulator is adapted to extend an electrical contacts to the electrical receptacles of each of the battery module and a plurality of interlocking blocks affixed at an outer surface of at least one face of the housing where. Each of the interlocking having a hole on the surface thereof and a plurality of locator pin disposed on an adjoining vertical surface of the vehicle. Each of the locator pin is adapted to mechanically secure a corresponding interlocking block and a slidable ratchet beneath the interlocking blocks comprising plurality of alternately placed slidable depressions to lock the interlocking blocks there within. Further, a second electrical receptacle extending there from at least one surface of the housing for establishing an electrical connection with the corresponding electrical contacts of the vehicle. [0031] FIG. 1 illustrates an apparatus for battery packaging for an electric vehicle. [0032] Referring to FIG. 1 , an apparatus ( 100 ) for battery packaging for an electric vehicle comprises a main structural housing ( 102 ), a configurable rack, a cooling vent ( 106 ), an interlocking block ( 108 ), a communication port ( 110 ), and a main electrical point ( 112 ). [0033] According to preferred embodiment of the invention, the housing ( 102 ) comprises an outer base surface and an inner base surface . The configurable rack is disposed on the inner base surface . The housing ( 102 ) is configured with the at least one cooling vent ( 106 ) such that it provides an air cooling to interior portion of the housing ( 102 ). The communication port ( 110 ) is disposed on the inner base surface adapted to provide current flow from the battery to the main electrical point ( 112 ). The main electrical point ( 112 ) is connected with the vehicle main vehicle electrical housing providing power to the vehicle. [0034] According to another embodiment of the invention, the housing ( 102 ) provides dual purpose of protecting the batteries and providing additional support to the overall structural performance of the vehicle. The interlocking block ( 108 ) is of adequate design to transmit structural load. The plurality of interlocking blocks ( 108 ) affixed at the outer surface of the housing ( 102 ), the interlocking block ( 108 ) having a hole ( 206 ) on the surface thereof. The interlocking blocks ( 108 ) are positioned on both sides of the housing ( 102 ). The interlocking blocks ( 108 ) provides support as attachment point for the housing ( 102 ). The interlocking blocks ( 108 ) can be coupled to structure disposed with a locator pin ( 502 ). According to exemplary embodiment of the invention, the interlocking blocks ( 108 ) are used to fix the apparatus ( 100 ) to the vehicle structure. According to another exemplary embodiment of the invention, the housing ( 102 ) is fabricated from a molded reinforced plastic such as fiber glass filled polypropylene. [0035] FIG. 2 illustrates an outer and inner base surface of main housing according to exemplary embodiments of the invention. [0036] Referring to FIG. 2 , the apparatus ( 100 ) further comprises a lid ( 208 ) for covering the housing ( 102 ) thus providing protection to the battery from water and dust ingress. The lid ( 208 ) is disposed with an attachment means for attaching the lid ( 208 ) with the housing ( 102 ) to make it complete assembly. The lid ( 208 ) is attached to the housing ( 102 ) via fastening means. According to one exemplary embodiment of the invention the fastening means are made from steel of sufficient grade to withstand calculated forces. The fastening means used in the invention is a screw. [0037] According to preferred embodiment of the invention, the apparatus ( 100 ) further comprises a bus bar ( 212 ) and a plug/connection block ( 214 ). The bus bar ( 212 ) is disposed on the inner surface of the housing ( 102 ) allowing the main voltage and current to be conducted. The plug/connection block ( 214 ) is disposed on the inner surface of the housing ( 102 ) allows a battery modules ( 302 ) to be plugged or unplugged. According to one exemplary embodiment of the invention, the bus bar ( 212 ) used is copper bus bar. [0038] FIG. 3 illustrates a battery housing disposed with the battery module according to one exemplary embodiment of the invention. [0039] Referring to FIG. 3 , according to preferred embodiment of the invention, the housing ( 102 ) comprises the configurable rack disposed on the inner base surface adapted to compactly accommodate the plurality of battery modules ( 302 ). The plurality of battery modules ( 302 ) has a first electrical receptacle at bottom thereof. The housing ( 102 ) is designed to achieve maximum configuration of the battery modules ( 302 ). [0040] According to another embodiment of the invention, the internal base surface ( 204 ) of the housing ( 102 ) covered with an electro-mechanical insulator ( 402 ) (shown in FIG. 4 ) and a pair of bus bar ( 212 ) mounted thereon, the electro-mechanical insulator ( 402 ) is adapted to extend an electrical contacts to the first electrical receptacles of each of the battery module ( 302 ). According to one exemplary embodiment of the invention, the electro-mechanical insulator ( 402 ) is manufactured from synthetic rubber. [0041] FIG. 4 illustrates positioning of electro-mechanical insulator according to one exemplary embodiment of the invention. [0042] Referring to FIG. 4 , the apparatus ( 100 ) for battery packaging is to be a structural member, the battery modules ( 302 ) may be mechanical insulated from the housing ( 102 ). This is achieved by disposing the electro-mechanical insulator ( 402 ) on the inner base surface and forming an insulated layer in order to protect the housing ( 102 ) from heat and electric leakage When the battery modules ( 302 ) are required to be structural member, the battery modules ( 302 ) are mechanically insulated from the housing ( 102 ) by inserting damping pads. Disposing of the electro-mechanical insulator ( 402 ) on the inner base surface such as damping pads is apparent to those skilled in the art. [0043] FIG. 5 illustrates a mechanism of battery packing apparatus located to the vehicle structure according to one exemplary embodiment of the invention. [0044] According to one embodiment of invention, to securely fix and hold the housing ( 102 ) to the body of the vehicle, the hole ( 206 ) of each interlocking block ( 108 ) is aligned with the locator pin ( 502 ) on the body of said vehicle and the locator pins ( 502 ) fit in the holes ( 206 ) of the interlocking blocks ( 108 ) as depicted in FIG. 5 . The final action that secures the apparatus ( 100 ) to the vehicle body is provided by sliding an interlocking bar ( 504 ) with matching vacancies that accommodate all of the interlocking blocks ( 108 ). [0045] The sliding bar ( 504 ) is securely fixed to the structural part of the vehicle body. It can be moved in and out of position using ratcheting mechanism. [0046] In an embodiment of the invention, connection between the vehicle and the battery module ( 302 ) is of adequate rigidity such that the battery modules ( 302 ) supports in structural performance of the vehicle. Bolts of threaded form are used in order to make the swapability effortless and during removal. [0047] FIG. 6 illustrates one possible configuration for air cooling of the battery. [0048] FIG. 7 illustrates battery pack configured for alternative capacity by varying the amount of the battery modules in the pack. EXAMPLE [0049] FIG. 8 illustrates an example for an integral battery apparatus contributing to overall vehicle structure. [0050] The integral battery pack ( 1 ) is rigidly attached to the vehicle frame. Considering a scenario of side impact, the force resulting from the impact ( 2 ) has to be absorbed by the vehicle structure ( 3 ) in a way to minimize danger to occupants. [0051] Using the integral battery modules ( 1 ), force can be absorbed in part by the overall vehicle structure ( 3 ) and in part by the battery module ( 4 ). Thus, the battery module( 1 ) can contribute to the structural strength of the vehicle. [0000] Operating Ranges Associated with the Invention: a) Battery total weight—120 to 200 kg b) Battery total volume—0.08 cu m to 1.4 cu m c) Air flow required—25 cu m per hour per kWhr of installed battery capacity time to swap out battery pack—less than 10 minutes ADVANTAGES OF THE INVENTION [0055] The technical advancements of the present invention include: The system is providing dual purpose of protecting the batteries and contributing to the overall structural performance of the vehicle. The system is also providing the space for battery modules which can be filled with a varying number of modules to achieve variable battery ratings. The system is making battery swapping simple and efficient.

4y

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heat resistant alloy member which is used at high temperatures or in corrosive environments at high temperatures. 2. Description of the Prior Art Techniques for improving the heat resisting property of structural members of gas turbines operated by high temperature gas have been investigated with a view for improving the thermal efficiency of gas turbine power stations. The establishment of the above-mentioned techniques is necessary for coal gasification power stations having higher cost of fuel in order to enhance its economically competitive ability against the other kind of power stations. There is therefore a demand for improved heat resisting alloy members in order to cope with the intention to increase the gas temperatures for gas turbine power stations. A principal method of providing members with heat resistance at higher temperatures is to develop new materials for forming such members. Among various types of metal materials, Ni or Co-based alloys have heat resistant temperatures of about 850° C. On the other hand, ceramics have a sufficient heat resisting property for high temperatures but involve certain problems with respect to their toughness and so on, particularly when they are used in moving blades which serves as high-speed rotors. Thus another method of achieving the technique for improving a heat resisting property is to prevent any increase taking place in the temperature of the relevant members. An example of this method is the combination of cooling members and coating members with ceramics having a low degree of thermal conductivity. Such a coating is called a thermal barrier coating (referred to as "TBC" hereinafter). TBC comprises a base metal composed of a heat resisting alloy and a coating of ceramics having physical properties which are different in numerical value from those of the base metal. An important technical problem of TBC is thus to reduce the thermal strain and thermal stress produced owing to the difference in the numerical values of the physical properties between the base metal and the ceramic coating. In particular, damage such as separation or the like may occur in the ceramic coating layer owing to the thermal stress based on a cyclic heating from starting to stopping of a gas turbine. A known method of reducing thermal stress is the method in which an intermediary layer is provided which serves to reduce the difference in thermal expansion coefficient between the ceramic coating layer and the base metal composed of a heat resisting alloy. Such an intermediary layer is disclosed in, for example, Japanese Patent Laid-Open No. 211362/1987. The intermediary layer is generally a mixture layer comprising ceramics and a metal. Although the thermal expansion coefficient of such a mixture layer depends upon the mixing ratio used, it is generally considered that the mixture layer should have a thermal expansion coefficient of a value midway between those of the ceramics and the metal. When this sort of mixture layer is interposed between a ceramic layer and a base metal, a function of reducing thermal stress can, as a matter of course, be expected. On the other hand, since the ceramic coating layer used in TBC is mainly formed by spray coating, it is a porous substance. This porous ceramic coating layer is capable of reducing thermal stress by itself by virtue of its porous structure. However, since the ceramic coating layer may be used in corrosive environments at high temperatures, high temperature oxidation or high temperature corrosion takes place in the mixture layer provided below the ceramic coating layer through the ceramic coating layer which consists of a porous substance. The inventors have thus conducted oxidation tests on mixture coating layers comprising ceramics and metals. Each of the test pieces employed was made by forming a mixture coating layer on a surface of a base metal and then removing the base metal to form a sample comprising a mixture. Each of the thus-formed test pieces was then subjected to an oxidation test under heating at 1000° C. for 1000 hours in the atmosphere. As a result, internal oxidation proceeded to a significant extent in each of the test pieces comprising mixtures in the oxidation tests. It is thought that such internal oxidation proceeds through cavities present at grain boundaries in the coating layers which comprises the mixture of ceramic powder and metal powder and which is simply formed by laminating the two types of powder by spray coating. Such internal oxidation in a mixture layer proceeded to a significant extent in a ceramic-coated test piece comprising a ceramic coating layer, a mixture layer and a base metal. The ceramic layer in this ceramic-coated test piece became separated after a high-temperature oxidation test at 1000° C. for 1000 hours. Thus the mixture layer provided for the purpose of reducing thermal stress cannot achieve the intended purpose. It is thought that the separation of the ceramic layer is caused by the thermal stress newly produced in the mixture layer owing to the internal oxidation in the mixture layer itself and by a reduction in the adhesion between the ceramic coating layer and the mixture layer owing to the oxidation at the boundary therebetween. Such a problem causes a reduction in the reliability of TBC. On the other hand, a thermal barrier effect required for TBC is increasingly improved as the working temperature of a gas turbine is raised. In other words, it is necessary to increase the thickness of the ceramic coating layer for the purpose of improving the thermal barrier effect. In this case, the thermal stress produced by a repeated heat load or the like is of course increased. It is therefore necessary to improve the durability of the ceramic coating by reducing the thermal stress produced in the ceramic coating layer owing to a repeated heat load or the like. As described above, although TBC provided with a mixture layer is provided for the purpose of reducing the thermal stress produced between a ceramic coating layer and a base metal, the mixture layer does not always possess a sufficient function of reducing thermal stress under high temperature conditions because the resistance to oxidation of the mixture layer at high temperatures is inadequate. In addition, the mixture layer does not always possess sufficient corrosive resistance at high temperatures. SUMMARY OF THE INVENTION Accordingly, it is an object of the present invention to provide a ceramic-coated heat resisting alloy member which enables a mixture layer comprising ceramics and a metal to exhibit its function of reducing thermal stress to an adequate extent even under corrosive conditions at high temperatures, this function of the mixture layer being the primary purpose of the provision thereof. The present invention provides a ceramic-coated heat resisting alloy member comprising a heat resisting alloy base metal, a mixture layer which comprises ceramics and a metal and which is deposited on the external surface of the base metal, and a ceramic coating layer which is deposited on the mixture layer, the alloy member being characterized in that an alloy layer comprising an alloy material which is superior to the base metal with respect to its resistance to high temperature oxidation and resistance to high temperature corrosion is provided on the outside of the mixture layer. The alloy layer has the function of protecting the mixture layer from oxidation and corrosion which proceed at high temperatures through the porous ceramic coating layer. That is, since the mixture layer comprises a mixture of ceramic grains and metal grains and has a thermal expansion coefficient of a value midway between those of the ceramics and the metal, it has the function of reducing the thermal strain produced between the ceramic coating layer and the heat resisting alloy base metal and the thermal stress produced owing to this strain. Since the mixture layer does not possess a sufficient degree of resistance to high temperature oxidation and or high temperature corrosion because cavities are present at the grain boundaries, however, the outside portion of the mixture layer is protected by the alloy layer provided between the mixture layer and the ceramic coating layer, whereby high temperature oxidation and high temperature corrosion are prevented. The mixture layer consequently remains stable even under conditions of high temperature oxidation and high temperature corrosion and is thus able to satisfactorily exhibit its primary function of reducing the thermal stress between the ceramic coating layer and the heat resisting alloy base metal. Examples of ceramics used in the present invention include ceramics containing ZrO 2 as a main component and Y 2 O 3 , MgO or CaO which is added thereto. The composition of the ceramics is at least one of ZrO 2 and 4 to 20 wt % of Y 2 O 3 , ZrO 2 and 4 to 8 wt % of CaO and ZrO 2 and 4 to 24 wt % of MgO. Spray coating powders of ZrO 2 -based ceramics having such a composition are produced by grinding and sizing ZrO 2 -based ceramics containing Y 2 O 3 , CaO or MgO which is formed by an electric melting method or a calcination method, each powder containing the above-described additive. Each of materials used for forming alloy layers contains at least one of Ni and Co as a main component, 13 to 40 wt % of Cr, 5 to 20 wt % of Al and a total content of 0.1 to 3 wt % of at least one of Hf, Ta, Y, Si and Zr. Alloys having such a composition has excellent resistance to high temperature oxidation and resistance to high temperature corrosion. In addition, heat resisting alloy base metals are super alloys having a composition comprising Ni as a main component, 7 to 20 wt % of Cr, 1 to 8 wt % of at least one of Ti and Al and Ta, Nb, W, Mo or Co, e.g., IN-738 (produced by Inconel Corp.) comprising Ni, 16% Cr, 8.5% Co, 3.4% Al, 3.4% Ti, 2.6% W, 1.7% Mo, 1.7% Ta, 0.9% Nb and 0.1% Zr, or a composition comprising Co as a main component, 25 to 35 wt % of Cr and Ni and W, e.g., FSX-414 (produced by GE Corp.) comprising Co, 30% Cr, 10% Ni, 2.0% Fe and 7.0% W. The ceramic-coated heat resisting alloy member in accordance with the present invention exhibits an improved level of durability as compared with conventional alloy members, and the durability does not deteriorate even if the thickness of the ceramic coating layer is increased. The heat resisting alloy member therefore makes a significant contribution to the inhibition of any increase in the temperature of the heat resisting alloy base metal. When the alloy layer is interposed between the ceramic coating layer and the mixture layer, as well as an oxide layer mainly composed of Al being formed at the boundary between the alloy layer and the ceramic coating layer, the same effect as that described above can be obtained, and the adhesion between the ceramic coating layer and the alloy layer is improved. Thus the level of durability can be maintained even if the thickness of the ceramic coating layer is increased for the purpose of improving the thermal barrier effect. The object, advantages and novel characteristics of the present invention are described in detail below with reference to the attached drawings. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic sectional view of an embodiment of the ceramic-coated heat resisting alloy member in accordance with the present invention; FIGS. 2, 3, 4 are respectively schematic sectional views of other embodiments of the ceramic-coated heat resisting alloy member in accordance with the present invention; and FIGS. 5 and 6 are respectively schematic sectional views of conventional ceramic-coated heat resisting alloy members. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention is described in detail below with reference to embodiments. FIG. 1 is a schematic sectional drawing of a ceramic-coated heat resisting alloy member in an embodiment of the present invention. FIGS. 5 and 6 are respectively schematic sectional views of conventional ceramic-coated heat resisting alloy members. In each of FIGS. 1, 5 and 6, reference numeral 1 denotes a ceramic coating layer; reference numeral 2, a heat resisting alloy base metal; reference numeral 3, an alloy layer comprising an alloy exhibiting resistance to high temperature oxidation and resistance to high temperature corrosion which are superior to the resistance of the base metal; and reference numeral 4, a mixture layer comprising the above-described alloy and ceramics. The material comprising the ceramic coating layer 1 is a ZrO 2 -type ceramics which is composed of ZrO 2 as a main component and Y 2 O 3 , MgO, CaO and so on as additional components. The material comprising the alloy layer 3 is composed of at least one of Co and Ni, Cr and Al and at least one of Hf, Ta, Y, Si and Zr. The mixture layer 4 comprises a mixture containing ZrO 2 -type ceramics and the alloy material. In the embodiment of the present invention shown in FIG. 1, the two alloy layers 3 may comprise the same alloy or alloys composed of different components. The method of forming each of the layers is not particularly limited, but a plasma spray coating method is preferable from the viewpoint of the high material deposition velocities and the good workability. An electron beam vacuum evaporation method or a sputtering method may be used as a method of forming a coating layer such as an alloy layer or the like with a relatively small thickness. EXAMPLE 1 An Ni-based alloy IN-738 was used as a base metal, and a surface thereof was then degreased and then subjected to blasting using an alumina grit. An alloy layer was then formed on the base metal by plasma spray coating using an alloy material comprising 32% by weight of Ni, 21% by weight of Cr, 8% by weight of Al, 0.5% by weight of Y and the balance composed of Co. The plasma spray coating was performed at pressure of 200 Torr in an atmosphere of Ar. The power of plasma was 40 kW. The alloy layer formed under these conditions had a thickness of 0.1 mm. A mixture comprising a ceramic powder containing ZrO 2 and 8% by weight of Y 2 O 3 and alloy powder having the above-described composition was then spray-coated on the alloy layer formed. The mixing ratio between the metal and ceramic power was 2:1. The conditions of spray coating were the same as those employed in the formation of the alloy layer. In this way, a mixture layer comprising the mixture of ceramics and a metal was formed on the alloy layer. The thickness of the mixture layer was 0.02 to 0.6 mm. An alloy powder having the above-described composition was then spray-coated on the mixture layer under the same conditions as those employed in the formation of the alloy layer to form an alloy layer having a thickness of 0.02 to 0.6 mm. A powder comprising ZrO 2 and 8% by weight of Y 2 O 3 was further spray-coated on the alloy layer formed. The spray coating was performed with a plasma power of 50 kW in the atmosphere. The thickness of the coating layer comprising ZrO 2 and 8% by weight of Y 2 O 3 was 0.3 to 1.2 mm. Heating treatment was then effected at 1120° C. for 2 hours under vacuum so that the base metal and the alloy layer in contact with the base metal were subjected to diffusion treatment. Conventional TBC test pieces comprising a base metal, an alloy layer and a ceramic coating layer and comprising a base metal, an alloy layer, a mixture layer and a ceramic coating layer were also produced for the purpose of comparison. The production conditions and coating material used were the same as those of the TBC test pieces of the present invention. Each of the test pieces had a size of 20 mm×70 mm×3 mm. Table 1 shows the results of repeated load tests conducted for the ceramic-coated test pieces of the present invention and conventional ceramic-coated test pieces which were formed for the purpose of comparison. In Table 1, Sample Nos. 1 and 8 concern the conventional ceramic-coated test pieces and Sample Nos. 9 to 23 concern the ceramic-coated test pieces of the present invention. Each of the repeated heat load tests was performed by repeatedly heating and cooling between 170° C. and 1000° C., and evaluation was conducted by examining the presence of damage in each of the ceramic-coated test pieces. The thickness of the ceramic coating layers in each of the ceramic-coated test pieces of the present invention is preferably 1.0 mm or less. TABLE 1______________________________________Results of Repeated Heat Load TestsThickness of (mm)Sample Ceramic Alloy Mixture AlloyNo. layer layer I layer layer II N*______________________________________ 1 0.3 -- -- 0.1 500 2 0.4 -- -- 0.1 250 3 0.6 -- -- 0.1 70 4 0.4 -- -- 0.05 230 5 0.4 -- 0.2 0.1 90 6 0.6 -- 0.2 0.1 45 7 0.8 -- 0.2 0.1 25 8 0.4 -- 0.4 0.1 120 9 0.4 0.1 0.2 0.1 125010 0.6 0.1 0.2 0.1 90011 0.8 0.1 0.2 0.1 75012 1.0 0.1 0.2 0.1 60013 1.2 0.1 0.2 0.1 9514 0.4 0.02 0.2 0.1 25015 0.4 0.03 0.2 0.1 90016 0.4 0.3 0.2 0.1 120017 0.4 0.5 0.2 0.1 80018 0.4 0.6 0.2 0.1 16019 0.4 0.1 0.02 0.1 27020 0.4 0.1 0.03 0.1 95021 0.4 0.1 0.3 0.1 110022 0.4 0.1 0.5 0.1 85023 0.4 0.1 0.6 0.1 200______________________________________ N*: Number of times of repeated heat load until damage occurs in ceramic coating There is a tendency that the durability of a test piece to the repeated heat load test deteriorates if the thickness of the ceramic coating layer is more than 1 mm, as in Sample No. 13 shown in Table 1. The thickness of the alloy layer (the alloy layer 1 shown in Table 1) between the ceramic coating layer 1 and the mixture layer 4 is preferably within the range of 0.03 to 0.5 mm. There is also a tendency that the durability to the repeated heat load test deteriorates if the thickness of the alloy layer I is out of the above-described range, as in Sample Nos. 14 and 18 shown in Table 1. If the thickness of the alloy layer I is small, the alloy layer is unsatisfactory as a layer for preventing any oxidation or corrosion through the ceramic coating layer. On the other hand, if the thickness of the alloy layer I is large, the alloy layer itself functions as a layer which newly produces thermal stress and thus cancels the thermal stress reducing function of the mixture layer 4. The thickness of the mixture layer 4 is preferably within the range of 0.03 to 0.5 mm. When the thickness of the mixture layer is out of the above-described range, as in Example Nos. 19 and 23 shown in Table 1, the durability to the repeated heat load test deteriorates. When the thickness of the mixture layer is small, the mixture layer has an unsatisfactory function of reducing thermal stress. While when the thickness of the mixture layer is large, the mixture layer itself has a relatively low level of strength, as compared with the alloy layer and so on, and is thus broken owing to the thermal stress produced by the increase in the thickness of the mixture layer. The thickness of the alloy layer II shown in Table I is not particularly limited, but it is preferably within the range of 0.03 to 0.5 mm. The reason for this is the same as the alloy layer I shown in Table 1. The mixing ratio between the ceramics and the metal in the mixture layer is not particularly limited. The mixing ratio of the metal to the ceramics in each of the mixture layers shown in Table 1 is 2/1. When the inventors have investigated mixture layers with other mixing ratios, the results obtained with the other mixing ratios were substantially the same as those shown in Table 1. Investigations have also been made on mixture layers in which a mixing ratio was gradually changed from a high ratio of metal to a high ratio of ceramics. The effect was not so clear and was substantially the same as that obtained by the provision of a mixing layer with a uniform mixing ratio. After each of the test pieces had been subjected to the high temperature oxidation test, it was subjected to a repeated heat load test which was the same as that described above. The temperature of the high temperature oxidation test was 1000° C., and the oxidation time was 500 hours. As a result, the ceramic coating layer of each of the ceramic-coated test pieces of Sample Nos. 5 to B shown in Table 1 was damaged and separated. On the other hand, as a result of repeated heat load tests of the other test pieces, each of the test pieces of Sample Nos. 1 to 4 exhibited a number of the times of heat load tests repeated until damage occurred which was reduced by 20 to 40% and thus exhibited deteriorated durability. While the ceramic-coated test pieces shown in Table 1 within the range of the present invention exhibited substantially the same results as those shown in Table 1. It was also observed that some of the test pieces within the range of the present invention exhibited increased numbers of the times of tests repeated until damage occurred. Each of the test pieces was then subjected to a high temperature corrosion test using a molten salt coating method. The test was conducted by a method in which a molten salt comprising 25% NaCl and 75% Na2SO4 was coated on each of the test pieces which was then heated at 850° C. for 300 hours in the atmosphere. Each of the test pieces was then subjected to the repeated heat lead test which was the same as that described above. As a result, the ceramic coating of each of the test pieces of Sample Nos. 5 to 8 shown in Table 1 was damaged after the high temperature corrosion test. The results of the repeated heat load tests showed that each of the test pieces of Sample Nos 5 to 8 exhibited a number of the times of tests repeated until damage occurred in the ceramic coating which was reduced by 20 to 0%, and thus exhibited slightly deteriorated durability. While the test pieces shown in Table 1 within the range of the present invention exhibited a number of the times of the tests repeated until damage occurred in the ceramic coatings which were the substantially the same as the results shown in Table 1 and particularly no deterioration in the durability thereof. FIGS. 2, 3 and 4 respectively show other embodiments of the present invention. In each of the embodiments, reference numeral 1 denotes a ceramic coating layer; reference numeral 2, a base metal; reference numeral 3, an alloy layer; reference numeral 4, a mixture layer; and a reference numeral 5, an oxide layer mainly composed of Al. In each of the embodiments shown in FIGS. 2 and 4, the oxide layer mainly composed of Al can be formed by heat treatment of the ceramic coated alloy member. The heat treatment is preferably carried out in the atmosphere under such conditions that the temperature is within the range of 600° to 1200° C. and the time is 1 to 200 hours. The thickness of each oxide layer is preferably 0.1 μm to 20 μm. If the oxide layer is thin, the oxide layer exhibits a reduced level of the effect, while if the oxide layer is thick, the oxide layer itself newly produces thermal stress. In each of FIGS. 3 and 4, the embodiment has a structure in which the mixture layer directly contacts with the base metal. In the ceramic coating of the present invention, since the thermal stress reducing function of the mixture layer is stably maintained under the conditions of high temperature oxidation or high temperature corrosion, there is no particular problem even if no alloy layer is interposed between the mixture layer and the base metal. Although the method of producing the alloy layer in any of the above-described ceramic-coated heat resisting alloy member of the present invention is not particularly limited, it is preferably to use plasma spray coating at a pressure which is reduced to a value below the atmospheric pressure in an atmosphere which comprises a shield gas or an inert gas. The method of producing the mixture layer of ceramics and a metal is the same as that above described. In the case of the alloy layer formed by plasma spray coating in an atmosphere at a reduced pressure, the alloy powder used is not easily oxidized during spray coating, and thus the alloy layer formed is a coating layer having a dense structure in which no contaminants such as oxide coating is mixed. In the mixture layer, the alloy powder comprising the mixture layer is not easily oxidized, and thus the metal portion in the mixture layer is a coating layer having no contaminants such as the oxide coating mixed therein. In addition, when each of the embodiments of the ceramic-coated heat resisting alloy member of the present invention shown in FIGS. 1 and 3 is used for a long period under conditions of high temperature oxidation, an oxide layer mainly composed of Al is formed at the boundary between the ceramic coating layer and the alloy layer. As described above, in each of conventional known ceramic-coated members, the mixture layer itself which comprises a mixture of a metal and ceramics is damaged and thus cannot exhibit its primary function of reducing the thermal stress produced between the ceramic coating layer and the base metal under the conditions of high temperature oxidation or high temperature corrosion. The mixture layer rather produces new thermal stress and thus exhibits durability which is inferior to that of a ceramic coating provided with no mixture layer, for example, in a repeated heat load test. While, in the ceramic coating of the present invention, the mixture layer exhibits its function of reducing thermal stress even at high temperature or under high temperature corrosive conditions and is thus effective to improve the durability of the ceramic coating. In addition, when the thickness of the ceramic coating layer is increased, the ceramic-coated heat resisting alloy member formed exhibits no deterioration in its durability, as well as exhibiting a high level of heat barrier effect and high performance. EXAMPLE 2 Pretreatment of an Ni-based alloy IN-738 which was used as a base metal was performed by the same method as in Example 1, and an alloy layer and a mixture layer were then formed using the materials and the method which were the same as those used in Example 1. The thickness of the alloy layer formed was 0.1 mm and the thickness of the mixture layer was 0.2 mm. The mixing ratios between the ceramics and the metals used in the mixture layers are as shown in Table 2. An alloy powder having the same composition as in Example 1 was then spray-coated on the mixture layers under the same conditions as those employed in Example 1 to form an alloy layer having a thickness of 0.1 mm. A ceramic layer was then formed on the alloy layer using the materials and the method which were the same as those employed in Example 1. The thickness of the ceramic layer was 0.4 mm. Heating treatment was then effected at 1120° C. for 2 hours under vacuum so that the base metal and the alloy layer in contact with the base metal were subjected to diffusion treatment. TABLE 2______________________________________Number of Times of Heat Load Tests Repeated UntilDamage Occurs in Ceramic CoatingTest Mixing ratio.sup.(4) (M/C)method 4/1 2/1 1/1 1/2 1/4______________________________________Repeated heat load test.sup.(1) 1170 1250 1200 1270 1150Repeated heat load test 1250 1170 1250 1350 1100after high temperatureoxidation test.sup.(2)Repeated heat load test 1100 1150 1150 1170 1050after high temperaturecorrosion test.sup.(3)______________________________________ .sup.(1) Repeated heat load test: 1000° C. .sub.[ 170° C. .sup.(2) High temperature oxidation test: 1000° C., 500 hours (heating in the atmosphere) .sup.(3) High temperature corrosion test: 850° C., 300 hours (25% NaCl + 75% Na.sub.2 SO.sub.4) .sup.(4) M/C: a ratio by volume of the metal to ceramics Each of the thus-formed ceramic-coated heat resisting alloy test pieces was then subjected to the repeated heat load test which was the same as that described above. Table 2 shows the number of the times of heat load tests repeated until the ceramic coating of each of the test pieces was damaged. In the high temperature oxidation tests at 1000° C. for 500 hours, no damage was observed in any ceramic coating after the oxidation tests. When the repeated heat load tests of the test pieces were conducted in the same way as that described above, the numbers obtained of the times of tests repeated until the ceramic coatings were damaged are shown in Table 2. When a molted salt comprising 25% NaCl and 75% Na 2 So 4 was then spray-coated on each of the test pieces which were then subjected to high temperature corrosion tests performed by heating in the atmosphere at 850° C. for 300 hours, no damage was observed in any ceramic coating. When the repeated heat tests using the test pieces which had been subjected to high temperature corrosion tests were conducted in the same manner as that described above, the number obtained of the times of tests repeated until each ceramic coating was damaged are shown in Table 2. On the other hand, a conventional ceramic-coated test pieces formed for the purpose of comparison showed substantially the same results as those exhibited by Samples Nos. 1 to 8 in Table 1. The ceramic coating of the present invention is therefore superior to conventional coating with respect to its resistance to high temperature oxidation and resistance to high temperature corrosion, as well as exhibiting excellent thermal durability. EXAMPLE 3 Pretreatment of a Ni-based alloy IN738 which was used as a base metal was effected by the same method as that employed in Example 1. An alloy layer and a mixture layer were then formed on the base metal using the materials and the method which were the same as those employed in Example 1. The mixing ratio between the ceramics and the metal in the mixture layer was 1:1. The thickness of the mixing layer was also the same as that in Example 1. An alloy layer having a thickness of 0.02 mm was then formed on the mixture layer by sputtering using as a target an alloy material comprising 32% by weight of Ni, 21% by weight of Cr, 8% by weight of Al, 0.5% by weight of Y and the balance composed of Co. The sputtering was performed under such conditions that the applied voltage was 2 kV and the treatment time was 2 hours. A ceramic coating layer was then formed in the same method as that employed in Example 1. Heat treatment was then effected at 1120° C. for 2 hours so that diffusion treatment was effected. When the thus-formed ceramic-coated heat resisting alloy test piece was subjected to the durability test in the same manner as that in Example 1, the results obtained were substantially the same as those in Example 1. EXAMPLE 4 A ceramic-coated heat resisting alloy test piece was formed by using the materials and the method which were the same as those employed in Example 1. The thus-formed test piece was then heated in the atmosphere at 950° C. for 20 hours to form an oxide layer mainly composed of Al 2 O 3 at the boundary between the ceramic coating layer and the alloy layer. As a result of observation of the cross-section texture of the test piece, the thickness of the oxide layer was about 5 μm. As a result of X-ray microanalyzing observation, Al and O were present in a large part of the portion which correspond to the oxide layer, with Cr being present in part of the portion. The thus-formed ceramic-coated heat resisting alloy test piece was then subjected to the durability test which was conducted in the same way as in Example 1. As result, the performance of the test piece was substantially the same as that obtained in Example 1. EXAMPLE 5 Pretreatment of a Co-based alloy FSX414 used as a base metal was performed by the same method as that employed in Example 1. A ceramic-coated heat resisting alloy test piece was formed by using the same materials those used in Example 1. The method of producing the test piece was a method in which a mixture powder comprising a metal and ceramics in a mixing ratio of 1:1 was spray-coated on a surface of the base metal. The spray coating was effected at pressure of 200 Torr in an atmosphere of Ar. The plasma power was 40 kW. The thickness of the mixture layer was 0.3 mm. An alloy layer was then formed on the mixture layer by spray coating under the same conditions as those employed in the formation of the mixture layer. The thickness of the alloy layer was 0.1 mm. A ceramic coating layer was then formed on the alloy layer by spray coating in the atmosphere with a plasma power of 50 kW. The thickness of the ceramic coating layer was 0.4 mm. The thus-formed ceramic-coated heat resisting alloy test piece of the present invention was then subjected to the durability test which was the same as in Example 1. The results obtained were substantially the same as those obtained in Example 1. EXAMPLE 6 A ceramic-coated heat resisting alloy test piece was formed by using the materials and the method which were the same as those employed in Example 5. The test piece was then heated in the atmosphere at 1000° C. for 15 hours to form an oxide layer mainly composed of Al 2 O 3 at the boundary between the ceramic coating layer and the alloy layer. As a result of observation of the cross-sectional texture of the test piece, the thickness of the oxide layer was about 7 μm. The result of X-ray microanalyzing observation showed that Al and O are present in a large area of the oxide layer, with Cr being present in part of the oxide layer. When the thus-formed ceramic-coated heat resisting alloy test piece of the present invention was then subjected to the durability test which was the same as that employed in Example 1, substantially the same results were obtained. As described above, the present invention is capable of preventing the progress of high temperature oxidation or high temperature corrosion of the mixture layer comprising a metal and ceramics. The function of reducing thermal stress which is the principal purpose of the provision of the mixture layer can thus be stably maintained, as well as the reliability of the ceramic-coated heat resisting alloy member formed being improved.

4y

TECHNICAL FIELD The present invention relates generally to diesel particulate filter systems, and more particularly to a diesel particulate filter system utilizing a ceramic filter to trap particulate exhaust in combination with a localized target of microwave absorbing media positioned in close proximity to regions of particulate buildup within the ceramic filter such that heating the target causes the particulate build-up to undergo combustion and vaporization so as to clean the filter. The cavity housing the ceramic filter and microwave absorbing media is adapted to accept inputs of microwave-frequency electromagnetic radiation through input couplers excited 90 degrees out of phase with each other to reduce radial non-uniformity in heating patterns across the target so as to promote uniform particulate removal across the filter. BACKGROUND OF THE INVENTION The use of ceramic filters to entrap particulates carried by a diesel engine exhaust flow is known. In operation, such ceramic diesel particulate filters accept exhaust flow at one end and trap particulates as exhaust gases diffuse through thin channel walls and exit out the other end. Particulate buildup which is allowed to continue causes the filter to become clogged thereby giving rise to an undesirable increased pressure differential across the filter and leading to back pressure that reduces the engine efficiency. Thus, it is necessary to clear the particulate buildup before critical levels of obstruction are achieved. Such particulate removal may be carried out by raising the temperature at the location of particulate buildup to a level above the flash point of the hydrocarbon particulates thereby causing combustion and vaporization of the particulates. Once the particulates are vaporized, the combustion products may be swept out of the filter by the exhaust stream. In order for localized heating to efficiently remove particulates from the filter, such heating is preferably applied across substantially the entire cross-section of the filter. In the event that zones across the filter cross-section are left unheated, the particulates at those zones will not be vaporized and the filter will develop a pattern of plugged zones. Thus, it is desired to provide an efficient method of uniform heating across substantially the entire plane of the filter so as to promote particulate combustion across the entire filter plane. The use of microwave-frequency electromagnetic radiation is known to be effective for heating dielectric materials in other environments. However, a challenge in using microwave-frequency radiation is the achievement of uniform temperature distributions across a target material. In particular, the use of microwave-frequency radiation in linearly polarized modes is highly susceptible to the creation of target hot sports and cold spots. As explained above, such nonuniformity is generally inconsistent with the requirements for particulate filter regeneration. Moreover, the environment of a particulate filter in a diesel exhaust system provides challenges with regard to space availability and cost constraints. Suitable systems for diesel exhaust filter regeneration based on microwave heating are not believed to have been previously available. SUMMARY OF THE INVENTION The present invention provides advantages and alternatives over the known art by providing a diesel particulate filter including a microwave-absorbing target at a defined position disposed within a waveguide cavity adapted to accept microwave-frequency electromagnetic radiation through input couplers 90 degrees out of phase with each other to excite circular polarization (CP) heating modes. Through excitation of CP modes, mode patterns are time-averaged azimuthally to smooth out the hot and cold spots in the heating pattern, thereby providing greater uniformity relative to corresponding linearly polarized modes. Still further uniformity may be realized by exciting combinations of CP modes so as to eliminate radial cold rings from the heating profile. It is contemplated that the microwave-absorbing target material is preferably embedded at or near the inlet end of the diesel particulate filter although other positions along the length of the filter may also be utilized if desired. The heating of the microwave absorbing media causes the particulate buildup to be vaporized and removed from the filter by the exhaust stream flow. BRIEF DESCRIPTION OF THE DRAWINGS The following drawings which are incorporated in and which constitute a part of this specification illustrate an exemplary embodiment of the present invention and, together with the general description above and the detailed description set forth below, serve to explain the principles of the invention wherein: FIG. 1 is a cut-away view of a diesel particulate filter system incorporating a microwave-absorbing target positioned across a ceramic filter within a cavity adapted to accept a split signal of microwave-frequency electromagnetic radiation through input couplers excited 90 degrees out of phase with each other to excite circular polarization (CP) heating modes; FIG. 2A illustrates the heating pattern of a target in a right circular cavity with conductive walls for the linearly polarized TE11 mode; FIG. 2B illustrates the heating pattern of a target in a right circular cavity with conductive walls for the circularly polarized TE11 mode according to the present invention; FIG. 3A illustrates the heating pattern of a target in a right circular cavity with conductive walls for the linearly polarized TE21 mode; FIG. 3B illustrates the heating pattern of a target in a right circular cavity with conductive walls for the circularly polarized TE21 mode according to the present invention; FIG. 4A illustrates the heating pattern of a target in a right circular cavity with conductive walls for the linearly polarized TE12 mode; FIG. 4B illustrates the heating pattern of a target in a right circular cavity with conductive walls for the circularly polarized TE12 mode according to the present invention; FIG. 5A illustrates the heating pattern of a target in a right circular cavity with conductive walls for the linearly polarized TE22 mode; FIG. 5B illustrates the heating pattern of a target in a right circular cavity with conductive walls for the circularly polarized TE22 mode according to the present invention; FIG. 6 illustrates the heating pattern of a target in a right circular cavity with conductive walls for excitation of the combination of circularly polarized TE11 and TE21 modes; and FIG. 7 is a plot of heating intensity relative to distance from the center of the target in FIG. 6 illustrating substantial uniformity over an extended portion of the radius. While embodiments of the invention have been illustrated and generally described above and will hereinafter be described in connection with certain potentially preferred embodiments and procedures, it is to be understood and appreciated that in no event is the invention to be limited to such embodiments and procedures as may be illustrated and described herein. On the contrary, it is intended that the present invention shall extend to all alternatives and modifications as may embrace the broad principles of this invention within the true spirit and scope thereof. DESCRIPTION OF THE PREFERRED EMBODIMENT Reference will now be made to the various drawings wherein to the extent possible like elements are designated by corresponding reference numerals in the various views. In FIG. 1 , there is illustrated a diesel particulate filter assembly 10 for disposition along the exhaust gas flow path down stream from a diesel engine (not shown). The direction of gas flow is illustrated by the directional arrow within the figure. According to the illustrated construction, the diesel particulate filter includes a cavity portion 12 that serves to contain a porous ceramic filter 14 and microwave-absorbing material 16 disposed in embedded contacting relation substantially across the cross-section of the filter 14 . The cavity portion 12 may be formed of suitable materials such as metal and the like. In such a construction utilizing a metal cavity the interior walls surrounding the filter 14 may be conductive. The microwave-absorbing material 16 may be any one or a combination of well known substances which undergo heating upon exposure to microwave radiation. By way of example, such materials may include SiC (Silicon Carbide), ITO (Indium-Tin Oxide), various ferrites, and the like including combinations of such materials as may be known to those of skill in the art. As illustrated, the diesel particulate filter assembly 10 is provided with a pair of microwave coupling input ports 20 as will be well known to those of skill in the art for operative connection to an external high power microwave source 22 of greater than 1 kW such as a standard 2.45 GHz/2 kW source as will be well known and readily available. Microwave reflectors 24 which permit gas flow but which prevent excess of trapped microwave energy are provided at the inlet and outlet ends of the diesel particulate filter assembly 10 . As illustrated, a 0-90 power divider 26 is disposed between the microwave source 22 and the input ports 20 . The power divider 26 modifies the power by dividing it equally between the two input ports while simultaneously shifting the phase of the signal delivered to one of the input ports by 90 degrees. The power divider is connected to the input ports via low loss connections. The input ports 20 are preferably situated on a plane of circular cross section and are spaced with an angular separation of approximately 90 degrees. The collective effect of the spacing between the input ports 20 and the 90 degree phase shift between the power signals delivered to the input ports is to excite a circularly polarized mode within the cavity 12 . By exciting circularly polarized modes, heating patterns are smoothed out azimuthally relative to linearly polarized modes to substantially eliminate the occurrence of hot and cold spots on a heated target in favor of transitional temperature rings thereby providing a more uniform average temperature profile. In operation, diesel exhaust enters through an inlet aperture 32 , passes into the filter 14 through intake channels, diffuses through the filter channel walls, flows out of the filter output channels and exits the cavity through the exhaust output aperture 34 . In the flow process, particulates carried by the exhaust flow are deposited where the gases diffuse through the channel walls upon exiting the filter. As the engine continues to run, the particulate mass builds up until the exhaust gas flow is impeded. At a selected optimum point based on measured back pressure within the system, the microwave power source 22 is activated such as by a switch connected to a pressure sensor (not shown) and microwave energy enters the chamber thereby heating the microwave-absorbing material 16 . The microwave-absorbing material 16 is disposed in close relation to the area of particulate buildup and as it absorbs energy, it heats to a point beyond the flash point of the accumulated hydrocarbon particulates. The particulates are thus ignited and are removed in vaporized form by the flow of exhaust gas. As previously noted, according to the potentially preferred practice, a circularly polarized mode is intentionally excited within the cavity to eliminate azimuthal variation. That is, points on a circular target defined by the microwave-absorbing material that are equidistant from the center are characterized by substantially the same heating profile regardless of their positional angle. This provides a degree of enhanced uniformity to the heating profile of the target by eliminating localized hot spots and cold spots. The enhanced uniformity in heating profile is illustrated by comparison of the heating patterns for linearly polarized modes illustrated in FIGS. 2A , 3 A, 4 A, and 5 A with those of the corresponding circularly polarized modes in FIGS. 2B , 3 B, 4 B and 5 B respectively. In particular, FIG. 2A illustrates the heating pattern of a target in a right circular cavity for the linearly polarized TE11 mode while FIG. 2B illustrates the heating pattern for the circularly polarized TE11 mode. FIG. 3A illustrates the heating pattern of a target in a right circular cavity for the linearly polarized TE21 mode while FIG. 3B illustrates the heating pattern for the circularly polarized TE21 mode. FIG. 4A illustrates the heating pattern of a target in a right circular cavity for the linearly polarized TE12 mode while FIG. 4B illustrates the heating pattern for the circularly polarized TE12 mode. FIG. 5A illustrates the heating pattern of a target in a right circular cavity for the linearly polarized TE22 mode and FIG. 5B illustrates the heating pattern for the circularly polarized TE22 mode. In these figures lighter regions correspond to higher temperatures while darker regions correspond to lower temperatures. As can be seen in FIGS. 2A , 3 A, 4 A and 5 A, the linearly polarized modes yield both radial variation and azimuthal or angular variation. That is, points that are equidistant from the center but at different angles relative to a hypothetical equatorial line may have temperatures that are substantially different from one another (i.e. azimuthal variation) as well as being different from points at the same angle but at different distances from the center (i.e. radial variation). Conversely, as illustrated in FIGS. 2B , 3 B, 4 B, and 5 B, the circularly polarized modes eliminate the occurrence of azimuthal variation, although radial variation in the form of rings at different distances from the center may still be present. The elimination of azimuthal variation allows a more regular temperature distribution across the target without hot and cold points. Thus, the available heating is more uniform overall. For example, the circularly polarized TE11, circularly polarized TE21 and circularly polarized TE22 modes exhibit temperature variations of less than 50% over more than 50% of the cross sectional surface area. This is a substantial improvement over the heating patterns for linearly polarized modes. While the single circularly polarized mode heating patterns represent a substantial improvement over linearly polarized mode heating patterns, it is contemplated that heating pattern uniformity may be improved still further by exciting combinations of circularly polarized modes that overlap to eliminate radial cold rings. By way of example only, and not limitation, FIG. 6 illustrates the heating pattern for the combination of the circularly polarized TE11 and TE21 modes which overlap to eliminate the hot spot in the center of the TE11 mode pattern and the high temperature zone near the wall of the TE21 mode pattern. A pattern with more gradual blended radial distribution is thus achieved. These benefits are illustrated graphically in FIG. 7 wherein it is seen that the intensity of the heating pattern varies less than 50% over the total cross section and varies less than 20% over 70% of the cross section. It is contemplated that standard microwave excitation techniques can be used to simultaneously excite two modes within the cavity 12 without any need to change the configuration of the source or input port configurations illustrated and described in relation to FIG. 1 . By way of example only, and not limitation, one technique for simultaneous excitation of two modes is to design the cavity radius and length to be simultaneously resonant in both modes by satisfying the resonant length equations for both modes. LB z,TE11 =n and LB z,TE21 =m Where L is cavity length, m and n are integers and B z,TE11 and B z,TE21 , are the respective axial mode wavenumbers. It is to be understood that while the present invention has been illustrated and described in relation to potentially preferred embodiments, constructions, and procedures, that such embodiments, constructions, and procedures are illustrative only and that the invention is in no event to be limited thereto. Rather, it is contemplated that modifications and variations embodying the principles of the invention will no doubt occur to those of ordinary skill in the art. It is therefore contemplated and intended that the present invention shall extend to all such modifications and variations as may incorporate the broad aspects of the invention within the true spirit and scope thereof.

4y

BACKGROUND OF THE INVENTION [0001] As the rules and regulations pertaining to automobile efficiency increase in severity, it is becoming increasingly important to consider sources of energy loss other than friction and other forces related to propulsion. For example, on a hot day, a vehicle's air-conditioning system may account for a noticeable fraction of the vehicle's energy use. To combat this loss of energy, certain steps are being taken to decrease the need for air-conditioning. One example of this is the use of solar control windows that reflect a substantial portion of incident solar radiation while maintaining substantial visible light transmittance. [0002] While this applied layer may serve the noted function, i.e., reducing solar heating of the vehicle interior, the inventors have observed that it can also cause problems with vehicle radio and other RF performance. Specifically, solar reflective glazing blocks radio waves from entering the vehicle, and therefore conventional antennae cannot be placed on the glass or inside the vehicle, including cellular and GPS antennae. Conventional vehicle antennae are configured such that the vehicle chassis serves as the antenna ground. This configuration may seriously degrade the performance of on-glass antennas at microwave frequencies, including 1-10 GHz, due to electrical distance from the chassis to the antenna. [0003] Thus, it is an object in part of this invention to take advantage of the solar-reflective glazing process by equipping vehicles with slot antennas, which can be patterned into a metallic solar-reflective glazing layer. Additionally, it is another object in part of the present invention to provide an antenna feed for a slot antenna capable of being adhered to solar-reflective glazing material with a virtual ground that is at a short electrical distance from the antenna. [0004] However, while these objects underly certain implementations of the invention, it will be appreciated that the invention is not limited to systems that solve the problems noted herein. Moreover, the inventors have created the above body of information for the convenience of the reader and expressly disclaim all of the foregoing as prior art; the foregoing is a discussion of problems discovered and/or appreciated by the inventors, and is expressly not an attempt to review or catalog the prior art. BRIEF SUMMARY OF THE INVENTION [0005] The invention provides an apparatus and method for providing an antenna feed to a slot antenna patterned or fabricated on a conductor layer sandwiched between dielectric layers, such as a solar-glazing conductor layer in a vehicle windshield, wherein the antenna feed may also provide a virtual ground without relying on either the vehicle chassis or an electrical connection to the conductor layer as the antenna ground. [0006] In one implementation, the slot antenna is patterned into a conductive film that is sandwiched between two dielectric layers, and the antenna feed is attached to one of the dielectric layers using electrically insulating adhesive or some other suitable method such that it partially covers the slot. The antenna feed accepts a coaxial cable and electromagnetically couples it to the slot antenna. The feed may comprise a printed circuit board with a signal trace, a ground trace, and a means to connect the coaxial cable or other two-conductor transmission line. The printed circuit board may be either flexible or rigid, and the coaxial cable may be connected by means of a connector or directly soldered to it. The signal trace is electrically connected to the center conductor of the coaxial cable, and the ground trace is electrically connected to the ground/shield of the coaxial cable. The signal trace travels towards the slot antenna and crosses the slot at least once (either perpendicularly or obliquely), thereby coupling the coaxial center conductor to the slot antenna, and the signal trace is terminated in an open circuit. [0007] In a further implementation, the ground trace may travel away from the slot and may take the form of a quarter-wave open circuited stub or a radial stub, thereby RF short-circuiting the coaxial shield to the ground plane and making the ground connection. [0008] Other objects and advantages of the invention will become apparent upon reading the following detailed description and upon reference to the drawings. BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS [0009] FIG. 1 is a schematic structural diagram of one implementation of an antenna feed for a slot antenna presenting a see-through view from above; [0010] FIG. 2 is a schematic structural diagram of the implementation shown in FIG. 1 from a cross-sectional side view; [0011] FIG. 3 is a schematic structural diagram of one implementation of an antenna feed in the context of a vehicle windshield coated with solar-reflective glazing presenting a see-through view of the vehicle windshield; [0012] FIG. 4 is a schematic structural diagram of the implementation shown in FIG. 3 from a cross-sectional view of the vehicle windshield. [0013] FIG. 5 is a flowchart illustrating a process for fabricating an antenna feed in the context of a vehicle windshield coated with solar reflective glazing. DETAILED DESCRIPTION OF THE INVENTION [0014] Turning to FIG. 1 and FIG. 2 , the components of an antenna system 100 ( 200 ) for a slot antenna include a plate or sheet of conductive material 101 ( 201 ) with a slot formed 103 ( 203 ), at least one dielectric layer 105 ( 205 ), and an antenna feed 107 ( 207 ). A slot antenna is a type of antenna made out of a sheet or plate of electrically conductive material, i.e., a conductive metal or alloy. A slot missing from the sheet or plate is used to radiate electromagnetic waves when a driving frequency is applied, similar to certain other types of antenna (e.g. the dipole antenna). Advantages of the slot antenna include its adaptability, light weight, simple structure, ease of fabrication, and high power capability. [0015] FIG. 1 depicts the system from above, while FIG. 2 depicts the system from a cross-sectional side perspective. It will be appreciated by one of ordinary skill in the art that the slot antenna may be a half-wave slot, full-wave slot, annular slot, or any other type of slot antenna, and that the positioning and physical properties of the various components can be varied depending on the desired antenna configuration. [0016] In one implementation, the antenna feed 107 ( 207 ) is a printed circuit board with a signal trace 109 , a ground trace 111 , and a connection point accepting a coaxial cable or other two-conductor transmission line 113 . The signal trace 109 travels towards the slot antenna and crosses the slot at least once either perpendicularly or obliquely. The signal trace 109 is terminated in an open circuit. The printed circuit board may be either flexible (e.g. Kapton film) or rigid (e.g. FR-4 fiberglass epoxy laminate). It will be appreciated by one of ordinary skill in the art that the printed circuit board is not limited to these two materials and may consist of other flexible or rigid materials. [0017] Turning now to FIG. 3 and FIG. 4 , the antenna system 100 ( 200 ) of FIG. 1 and FIG. 2 is depicted in the context of the solar-reflective glazing of a vehicle windshield 300 ( 400 ). FIG. 3 depicts a straight-on view of the windshield, while FIG. 4 depicts a cross-sectional view of the windshield. For simplicity, only a section of the windshield 300 ( 400 ) and the solar-reflective glazing layer 301 ( 401 ) are depicted, and details from the antenna feed 309 ( 107 ) are omitted. The solar-reflective glazing layer 301 ( 401 ) is located between two dielectric layers 305 and 307 , e.g., comprising tempered glass or the like in a typical windshield. The conductive material used for solar-reflective glazing is patterned or fabricated with a slot 303 ( 403 ) such that the solar-reflective glazing layer 301 ( 401 ) can be used as a slot antenna. The antenna feed 309 ( 409 ) may then be adhered to the windshield 300 ( 400 ) in an appropriate orientation with respect to the slot antenna using a non-conductive adhesive 411 . A coaxial cable or other two-conductor transmission line 315 may be connected to the coaxial connection point 313 on the antenna feed 309 ( 409 ) to drive the antenna. It will be appreciated by one of ordinary skill in the art that the positioning of the slot antenna within the solar-reflective glazing layer may be arbitrarily varied and is not limited to the corner as shown. It will also be appreciated that different types of solar-reflective glazing material and dielectric material can be used. [0018] Turning back to FIG. 1 , with further reference to the context of FIG. 3 and FIG. 4 , in a further implementation, the ground trace 111 travels away from the slot and may take the form of a quarter-wave open circuited stub or a radial stub 115 . A quarter-wave open circuited stub or a radial stub may RF short-circuit the coaxial shield to the ground plane and act as a virtual ground for the slot antenna. This implementation allows the slot antenna system to be grounded a very short electrical distance from the slot antenna, enabling efficient excitation of microwave antennas. It also allows the placement of the antenna at arbitrary distances from the vehicle chassis, as the ground is no longer dependent upon the vehicle chassis. [0019] Turning to FIG. 5 , the process 500 for providing an antenna feed to a slot antenna patterned or fabricated into a conductive solar-reflective glazing layer is shown via the illustrated flowchart. First, a conductive solar-reflective layer may be patterned or fabricated with a slot at stage 501 , wherein the properties of the slot depend on the desired antenna configuration. A printed circuit board comprising a signal trace, a ground trace, and a connection point for a coaxial or other two-conductor cable may also be prepared for use as an antenna feed at stage 503 . The signal trace may be printed such that it ends in an open circuit. The ground trace is printed such that it provides a virtual ground to the antenna system, and may take the form of a quarter-wave open circuited stub or a radial stub. The solar-reflective glazing layer is disposed between the two glass layers of the windshield at stage 505 . [0020] The antenna feed may then be attached to the windshield at stage 507 using non-conductive adhesive (or another suitable method) such that the signal trace of the antenna feed crosses the slot at least once, either perpendicularly or obliquely, and the ground trace of the antenna feed travels away from the slot. A coaxial cable or other two-conductor cable is then connected to the connection point on the antenna feed at stage 509 . The coaxial or other two-conductor cable may be attached to the connection point by a standard connection unit or may be directly soldered together. [0021] It will be appreciated by one of ordinary skill in the art that some processes depicted by FIG. 5 may be performed in a different order or in parallel. For example, a coaxial or other two-conductor cable may be attached to the antenna feed before the antenna feed is adhered to the dielectric. [0022] It will be appreciated that the described system and method provide an antenna feed for a slot antenna that may be patterned into a solar-reflective glazing layer with a virtual ground that is a short electrical distance from the antenna. It will also be appreciated, however, that the foregoing methods and implementations are merely examples of the inventive principles, and that these illustrate only preferred techniques. [0023] It is thus contemplated that other implementations of the invention may differ in detail from foregoing examples. As such, all references to the invention are intended to reference the particular example of the invention being discussed at that point in the description and are not intended to imply any limitation as to the scope of the invention more generally. All language of distinction and disparagement with respect to certain features is intended to indicate a lack of preference for those features, but not to exclude such from the scope of the invention entirely unless otherwise indicated. [0024] The use of the terms “a” and “an” and “the” and similar referents in the context of describing the invention (especially in the context of the following claims) are to be construed to cover both the singular and the plural, unless otherwise indicated herein or clearly contradicted by context. The terms “comprising,” “having,” “including,” and “containing” are to be construed as open-ended terms (i.e., meaning “including, but not limited to”) unless otherwise noted. Recitation of ranges of values herein are merely intended to serve as a shorthand method of referring individually to each separate value falling within the range, unless otherwise indicated herein, and each separate value is incorporated into the specification as if it were individually recited herein. All methods described herein can be performed in any suitable order unless otherwise indicated herein or otherwise clearly contradicted by context. The use of any and all examples, or exemplary language (e.g., “such as”) provided herein, is intended merely to better illuminate the invention and does not pose a limitation on the scope of the invention unless otherwise claimed. No language in the specification should be construed as indicating any non-claimed element as essential to the practice of the invention. [0025] Accordingly, this invention includes all modifications and equivalents of the subject matter recited in the claims appended hereto as permitted by applicable law. Moreover, any combination of the above-described elements in all possible variations thereof is encompassed by the invention unless otherwise indicated herein or otherwise clearly contradicted by context.

4y

BACKGROUND This invention relates generally to data centers, and more particularly to efficient cooling of computing devices within a data center. Heat removal is a prominent factor in computer system and data center design. The number of servers deployed in a data center has steadily increased while the increase in server performance has increased the heat generated by the electronic components in the servers during operation. Because the reliability of servers used by the data center decreases if they are permitted to operate at a high temperature over time, a portion of the data center's power is used for cooling electronics in the servers. As the number or servers included in a data center increases, a greater portion of the power consumed by the data center is used to cool electronics within the server. Conventionally, the servers in the data center are individually equipped with a cooling system to dissipate heat produced during operation. Commonly, each server includes a fan to dissipate heat generated by the server during operation. However, these internal fans generally consume about 10%-15% of the power used by the servers, and they also produce heat during operation, thereby limiting the ability of these fans to dissipate heat. Additionally, in conventional configurations, an internal server fan is initiated to cool the server when the server temperature reaches a threshold temperature. As the server temperature is dependent upon the number of data processing requests, data retrieval requests, data storage requests or other requests processed by the server, the number of requests processed by a server are limited so that a temperature spikes during processing of requests does not cause the server to exceed the threshold temperature. Hence, operation of conventional internal fans impairs server performance by placing an upper bound on the number of requests that can be processed by a server. SUMMARY Embodiments of the invention balance the number of requests, or “load,” processed by a plurality of servers and use an external cooling supply to cool servers within a data center. Hence, embodiments of the invention reduce or eliminate the need for internal fans to cool servers in a data center, at least under normal operating conditions, and dynamically adjust the number of requests processed by various servers to avoid large variations in the temperature of different servers. In one embodiment, a data center includes a cold aisle adjacent to one side of a set of server that that receives cold air from a cooling system. An exhaust system included in a hot aisle adjacent to a second side of the servers directs air from the hot aisle outside of the data center, causing the hot aisle to have a pressure less than the pressure of the cold aisle. This pressure difference between the cold aisle and the hot aisle causes cold air to flow from the cold aisle through the servers to the hot aisle, thereby cooling the electronic components in the servers (and heating the air flow). For example, a fan included in the hot aisle extracts heated air from the hot aisle and directs the heated air outside of the data center. In one embodiment, one or more sensors monitor the pressure of the hot aisle and the pressure of the cold aisle and calculate a pressure difference between the hot aisle and the cold aisle. Additionally, the one or more sensors may also monitor air flow proximate to the servers. A load balancer receives requests for processing by one or more servers from one or more devices and also receives the calculated pressure difference. For a plurality of servers in the data center, the load balancer includes data associating a workload with a pressure difference. For example, data stored in the load balancer identifies a maximum workload capable of being processed by a server for a pressure difference without increasing the temperature of a server beyond a threshold temperature. In one embodiment, the load balancer includes a table associating a workload with a pressure difference for each server in the data center. In a different embodiment, the load balancer includes a table associating a maximum workload with a pressure difference for different types or models of servers included in the data center. Based on the calculated pressure difference and the maximum workload associated with the pressure difference for each server, the load balancer determines a number of requests for communication to different servers. For example, based on the maximum workload associated with the calculated pressure difference, the load balancer directs requests to various servers to maximize the number of requests processed by different servers without increasing server temperature above a threshold amount. In an embodiment, a cold air supply unit that is external to the servers, such as a fan, supplies the cold air to the cold aisle from a cooling system to contribute the pressure difference between the cold aisle and the hot aisle. The heated air from the hot aisle may be cooled and then recirculated through the cold aisle, or the cool air may be obtained elsewhere, such as ambient air. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a side view of a data center for cooling servers without relying on internal fans showing airflow throughout the data center in accordance with an embodiment of the invention. FIG. 2A is a tabular example of data included by a load balancer for a server associating a pressure difference with a server workload in accordance with an embodiment of the invention. FIG. 2B is a graphical example of using data included by a load balancer to determine a workload for different servers based on a pressure difference in accordance with an embodiment of the invention. The Figures depict various embodiments of the present invention for purposes of illustration only. One skilled in the art will readily recognize from the following discussion that alternative embodiments of the structures and methods illustrated herein may be employed without departing from the principles of the invention described herein. DETAILED DESCRIPTION Data Center Architecture One embodiment of a data center 100 cooling one or more servers 105 is illustrated in FIG. 1 , which shows a side view of the airflow through data center 100 that is capable of cooling the servers 105 without depending on fans within the servers 105 . The arrows shown in FIG. 2 indicate the flow of air throughout the data center 100 . A cooling system 130 is coupled to a cold air supply 115 and to an exhaust unit 125 . While FIG. 1 shows a single cold air supply 115 and a single exhaust unit 125 , other embodiments may have multiple cold air supplies 115 and/or multiple exhaust units 125 . A load balancer 160 receives requests for processing from one or more clients and communicates the requests to one or more servers 105 for processing. A control system 150 is coupled to the load balancer 160 and to the exhaust unit 125 , allowing data from the load balancer 160 to modify control signals communicated to the exhaust unit 125 . In one embodiment, a cold aisle 110 is adjacent to a first side of a partition 102 and a hot aisle 120 is adjacent to a second side of the partition 102 . In an embodiment, the partition 102 includes one or more servers 105 oriented so that a first side of the one or more servers 105 is adjacent to the cold aisle 110 and a second side of the one or more servers 105 is adjacent to the hot aisle 120 . The cold aisle 110 includes a cold air supply 115 while, in an embodiment, the hot aisle 120 includes one or more exhaust units 125 . Additionally, one or more sensors 117 proximate to one or more servers server 105 , are included in the cold aisle 110 and in the hot aisle 120 . The partition 102 includes one or more openings though which air is able to flow. In an embodiment, the partition 102 comprises a rack or other structure to which one or more devices, such as one or more servers 105 or other electronic devices, may be attached. For example, the one or more servers 105 are mounted to one or more racks and the one or more servers 105 may have different sizes, such as 1 to 12 rack units (“U”). The partition 102 is designed to increase airflow through the servers 105 included within the partition 102 . For example, the partition 102 includes a server rack that is designed to increase the amount of air directed through the servers 105 included in the rack. A server 105 has one or more input openings on a first side and one or more output openings on a second side. A server 105 is oriented so the one or more input openings are adjacent to the cold aisle 110 and the one or more output openings are adjacent to the hot aisle 120 . Air from the cold aisle 110 enters the server 105 via the one or more input openings, travels through the server 105 and exits the server through the one or more output openings into the hot aisle 120 . Hence, the input and output openings allow air to travel through the server 105 to cool components included in the server 105 . In another embodiment, the system further includes air ducts configured to direct the cold air over the hot server components. Cold air is supplied to the cold aisle 110 from a cold air supply 115 , such as a large fan or other air distribution device. In an embodiment, the cold air supply 115 is coupled to a cooling system 130 , further described below. As used herein, “cold air” may refer to air having a temperature less than an ambient air temperature, air having a temperature below a specified temperature, or air having a lower relative temperature than air in a different region. For example, air included in the cold aisle 110 , referred to as “cold air,” has a first temperature, while air included in the hot aisle 120 , referred to as “hot air,” has a second temperature that is higher than the first temperature. In different embodiments, the position of the cold air supply 115 relative to the cold aisle 110 may differ. For example, the cold air supply 115 may be positioned above, below, or to the side of the cold aisle 110 . Additionally, in some embodiments, multiple cold air supplies 115 provide cold air to the cold aisle 110 and may have different positions relative to the cold aisle 110 . For example, cold air supplies 115 are positioned above and below or below and to the side of the cold aisle 110 . For purposes of illustration, FIG. 1 shows an implementation with a cold air supply 115 positioned above the cold aisle 110 . By receiving cold air from the cold air supply 115 , the cold aisle 110 has a higher pressure than the hot aisle 120 . This pressure difference causes cold air to flow from the higher pressure cold aisle 110 through the one or more input openings of a server 105 , or of the partition 102 , to the lower pressure hot aisle 120 . The cooling system 130 comprises a Heating, Ventilating and Air Conditioning (“HVAC”) system, which extracts heat from air. For example, the cooling system 130 uses free-air cooling, such as air-side or liquid-side economization to cool the air. In an embodiment, the cooling system 130 also includes secondary cooling systems, such as an evaporative cooling system, an absorption cooling system, an adsorption cooling system, a vapor-compression cooling system, or another cooling system to extract additional heat from air. In another embodiment, the cooling system 130 also modifies the humidity of the cool air to improve reliability and/or longevity of the servers 105 being cooled. For example, the cooling system 130 produces cold air having a humidity within a specified range, such as 20% to 60% humidity, to the cold aisle 110 . In certain conditions, increasing the humidity may also reduce the temperature of the air. One or more exhaust units 125 are included in the hot aisle 120 to extract air from the hot aisle 120 and to direct air from the hot aisle 120 outside of the data center 100 . In one embodiment, the one or more exhaust units 125 direct air from the hot aisle 120 to the cooling system 130 , where the heated air is again cooled. Hence, the one or more exhaust units 125 may implement a closed-loop where air is cooled by the cooling system 130 and recirculated to the cold aisle 110 via the cold air supply 115 . Alternatively, cold air enters the hot aisle 120 and is directed outside of the data center 100 by the one or more exhaust units 125 . In an embodiment, the hot aisle 120 includes one or more exhaust units 125 , such as exhaust fans, which extract air from the hot aisle 120 . While FIG. 1 shows an example hot aisle 120 with one exhaust unit 125 , in other embodiments, the hot aisle may include a different number of exhaust units 125 . The one or more exhaust units 125 receive control signals from a control system 150 . The control signals modify one or more operating characteristics of the one or more exhaust units 125 to modify the pressure difference between the cold aisle 110 and the hot aisle 120 . For example, in response to receiving a control signal from the control system 150 , an exhaust fan operates at a higher speed to extract more heated air from the hot aisle 120 and increase the pressure difference between the cold aisle 110 and the hot aisle 120 . As another example, responsive to receiving a second control signal from the control system 150 , the exhaust fan operates at a lower speed to extract less heated from the hot aisle 120 and decrease the pressure difference between the cold aisle and the hot aisle 120 . By modifying operation of one or more exhaust units 125 , the control system 150 is able to modify the amount of air travelling through the one or more servers 105 and/or the partition 102 by adjusting the pressure drop between the cold aisle 110 and the hot aisle 120 . The control system 150 may also modify the operation of the fan driving the cold air supply 115 . Moreover, the system need not have fans on both the cold aisle 110 and the hot aisle 120 , as a single fan on either side may create sufficient pressure to cause the air to flow the servers. In such a case, the control system 130 may drive this single fan. The load balancer 160 is coupled to the exhaust unit 125 and also communicates with a plurality of servers 105 . Additionally, the load balancer 160 receives requests from one or more computing devices and communicates the received requests to one or more servers 105 . For example, the load balancer 160 receives requests from a computing device for a server 105 to process data, requests from a computing device for a server 105 to retrieve data, requests from a computing device for a server 105 to store data or other requests for a server 105 to manipulate or modify data. The load balancer 160 also includes data includes data associating a number of requests for processing by a server 105 , or a server “workload” with a pressure difference between the cold aisle 110 and the hot aisle 120 . For example, data stored in the load balancer 160 identifies a maximum number of requests capable of being processed by a server 105 for a pressure difference between the cold aisle 110 and the hot aisle 120 . The maximum number of requests indicates the number of requests which can be processed by a server 105 at a specific pressure difference without increasing the temperature of a server 105 beyond a threshold temperature or without increasing the temperature of the server 105 by a threshold amount. For example, the load balancer 160 includes a table associating a server workload with a pressure difference for each server 105 in the data center 100 . In a different embodiment, the load balancer includes a table associating a server workload with a pressure difference for different types, or groups, of servers 105 included in the data center 100 . If organized into groups, the servers 105 may be selected for a group wherein the servers 105 in a group generate the same amount of heat for a given load. In one embodiment, the load balancer 160 receives the pressure difference between the cold aisle 110 and the hot aisle 120 from one or more sensors 117 in the hot aisle 120 and in the cold aisle 110 . Alternatively, the load balancer 160 receives an absolute pressure of the cold aisle 110 from a sensor 117 included in the cold aisle 110 and an absolute pressure of the hot aisle 120 from a sensor 117 included in the hot aisle 120 and calculates the pressure difference between the cold aisle 110 and the hot aisle 120 . In a typical server, there may be a correlation between the server work load and the power consumed by the server, as well as a correlation between the air flow through the server, or the pressure differential across the server, and the ability to remove a given amount of heat from the server. Based on the pressure difference, the load balancer 160 determines from the stored data the maximum number of requests a server 105 is capable of processing and directs requests to different servers 105 based on the maximum number of requests a server 105 is capable of processing based on the pressure difference. For example, the load balancer directs requests to different servers 105 so that each server processes the same number of requests or so that the workload of various servers 105 is maximized with respect to the pressure difference. Hence, the load balancer 160 maximizes the amount of work done by different servers 105 for a specified pressure difference between the cold aisle 110 and the hot aisle 120 . By distributing requests to different servers 105 based on the pressure difference between the cold aisle 110 and the hot aisle 120 , the load balancer 160 regulates the workload of different servers 105 to reduce temperature variations between different servers 105 . This increases the efficiency with which different servers 105 are cooled for a specific pressure difference between the cold aisle 110 and the hot aisle 120 . Operation of the load balancer 160 to regulate server 105 load is further described below in conjunction with FIGS. 2A and 2B . The coupling between the load balancer 160 and the control system 150 allows the load balancer 160 to modify operation of one or more exhaust units 125 . For example, as the workload of various servers 105 increases beyond the maximum server workload for a first pressure difference, the load balancer 160 causes the control system 150 to generate a control signal increasing the amount of air that the exhaust unit 125 draws out of the hot aisle 120 , which increases the pressure difference between the cold aisle 110 and the hot aisle 120 . By modifying operation of the exhaust unit 125 in response to increases in server workload, the load balancer 160 allows dynamic modification of server cooling 105 . In one embodiment, the cooling system 130 receives heat from the exhaust units 125 included in the hot aisle 120 , cools and dehumidifies the received air, and supplies the cooled and dehumidified air to the cold air supply 115 which supplies the cooled and dehumidified air to the cold aisle 110 . In this embodiment, the cooling system 130 may be a closed system which recirculates air from the hot aisle 120 to the cold aisle 110 once the air is cooled and dehumidified. Cooled air travels from the cooling system 130 to the cold air supply 115 , which supplies the cold air to the cold aisle 110 . In an embodiment, the cold air supply 115 comprises one or more fans or one or more air nozzles, one or more air jets, or other device for directing air flow. Cooled air from the cold air supply 115 enters the cold aisle 110 . Because the cold aisle 110 has a higher pressure than the hot aisle 120 , and the partition 102 includes one or more openings for air flow, the cold air flows from the cold aisle 110 to the lower pressure hot aisle 120 . To flow from the cold aisle 110 to the hot aisle 120 , the cold air passes through the openings in the partition 102 , so that the cold air is drawn through the partition 102 . In an embodiment, the partition 102 includes one or more servers 105 having one or more input openings on a first side adjacent to the cold aisle 110 and one or more output openings on a second side adjacent to the hot aisle 120 . The input openings allow cold air to enter the server 105 , travel through the server 105 , flowing over components within the server 105 . After traveling through the server 105 , the output openings enable air to exit the server 105 into the hot aisle 120 . As cool air travels through the partition 102 and/or a server 105 from the cold aisle 110 to the hot aisle 120 , a portion of the air travels across, or through, one or more sensors 117 included in the cold aisle 110 and in the hot aisle 120 . The sensors 117 monitor attributes of the airflow, such as air temperature, air humidity, absolute air pressure of the cold aisle 110 , absolute air pressure of the hot aisle 120 or a pressure difference between the cold aisle 110 and the hot aisle 120 . The sensors 117 communicate the monitored attributes to the control system 150 and/or the load balancer 160 . The control system generates a control signal modifying operation of the cold air supply 115 and/or the cooling system 210 to modify the cold air supplied to the cold aisle 110 . For example, responsive to a sensor 117 detecting a temperature above a threshold value, an air flow below a threshold flow rate or a pressure difference between the cold aisle 110 and the hot aisle 120 falling below a threshold value, the control system generates a control signal increasing the rate or direction at which the cold air supply 115 supplies cold air to the cold aisle 110 or generates a control signal directing cold air from the cold air supply 115 towards certain areas in the cold aisle 110 needing increased cooling. For example, the control signal causes the cold air supply 115 to more cold air towards a region of the partition 102 where a sensor 117 indicates a temperature above a threshold value or an airflow rate below a threshold value. Alternatively, the control system generates a control signal causing the cooling system 210 to further reduce the temperature of the air provided to the cold aisle 110 . In an embodiment, the partition 102 is configured so that air flow paths external to the servers 105 are substantially blocked such that the airflow path of least resistance from the cold aisle 110 to the hot aisle 120 is through the servers 105 . Configuring the partition 102 so that the airflow path of least resistance is through the servers 105 allows more efficient server 105 cooling by increasing the amount of air passing through the servers 105 . In another embodiment, the partition 102 blocks substantially all airflow from the cold aisle 110 to the hot aisle 120 except for the airflow through the servers 105 , so that substantially all of the airflow from the cold aisle 110 to the hot aisle 120 is through the servers 105 . To facilitate airflow from the cold aisle 110 to the hot aisle, in one embodiment the cold aisle 110 may be pressurized while the hot aisle 120 is depressurized to facilitate airflow from the cold aisle 110 to the hot aisle 120 . As the cold air passes through the server 105 , it flows over components within the server 105 , dissipating heat generated from operation of the electric components in the servers 105 . In different embodiments, the cold air supply 115 may statically or dynamically control the amount of air supplied to the cold aisle 110 to modify the airflow through the servers 105 . In an embodiment where the air supply is statically controlled, the cold air supply 115 is louver-based and supplies cold air in different directions, at different flow rates, and/or at different temperature levels. In an alternative embodiment, the cold air supply 115 dynamically modifies the airflow supplied to the cold aisle 110 by changing the speed of one or more supply fans, repositioning one or more air supply louvers (or otherwise redirecting the airflow), or changing the temperature to which the airflow is cooled. Modifying the supply fan speed, supply louver position, and/or air temperature allows the cold air supply 115 to more suitably cool the servers 105 included in the partition 102 . Hence, implementations of the cold air supply 115 allow non-uniform air flow and/or air temperature throughout the cold aisle 110 , enabling different locations within the cold aisle 110 , such as locations proximate to different servers 105 , to have a different air flow rate and/or a different air temperature. Additionally, the air flow from the cold air supply 115 may be determined or modified based on the size of the servers 105 being cooled. After flowing through the servers 105 , cold air enters the hot aisle 120 because it has a lower pressure than the cold aisle 110 . Because the air extracts heat from components within one or more servers 105 , when passing from the cold aisle 110 to the hot aisle 120 , the air temperature increases so that air in the hot aisle 120 has a higher temperature than air in the cold aisle 110 . The data center 100 also includes one or more sensors 117 in locations where air flows from the cold aisle 110 to the hot aisle 120 . The sensors 117 monitor air flow, air temperature, air humidity, absolute air pressure, differential air pressure, or any other data that describes air flow or air temperature, and combinations thereof. In an embodiment, the sensors 117 are placed in locations where airflow is likely to be less than other locations, such as a ceiling or a wall where the partition 102 abuts another surface, so that the temperature of the sensor locations is likely to be higher than other locations. For example, sensors 117 are placed in various locations in the cold aisle 110 to monitor airflow through these locations, the temperature of these locations, the pressure difference between the cold aisle 110 and the hot aisle 120 or another value characterizing air flow through the sensor location. In another embodiment, sensors 117 are positioned at locations within the cold aisle 110 , at locations within the hot aisle 120 , at locations within one or more servers 105 or in any combination of the above-described locations. The sensors 117 communicate with a control system coupled to, or included in, the cooling system and/or the cold air supply 115 to modify how air is cooled by the cooling system or how cold air is supplied to the cold aisle 110 by the cold air supply 115 . The control system generates a control signal responsive to data from one or more sensors 117 to modify operation of the cooling system and/or the cold air supply 115 . For example, responsive to detecting a temperature reaching a threshold value, an air flow reaching a threshold flow rate, or a pressure difference between the cold aisle 110 and the hot aisle 120 falling below a threshold value, a sensor 117 communicates with the control system, which generates a control signal increasing the rate at which the cold air supply 115 supplied to the cold aisle 110 or modifying the direction in which cold air is supplied to the cold aisle 110 by the cold air supply 115 . Hence, the sensors 117 and control system implement a feedback loop allowing the data center 100 to modify how cold air flows through the servers 105 responsive to changes in the data center environment, improving the cooling efficiency. Because the pressure differential between cold aisle 110 and hot aisle 120 causes air to flow through the partition 102 , and electronic devices included in the partition 102 , electronic devices included in the data center 100 are cooled without relying on air moving devices, such as fans, operating at individual electronic devices. Additionally, reducing the use of locally-implemented air moving devices reduces power consumption of the electronic devices, making the data center 100 more power efficient. This is due, at least in part, to the increased efficiency of the larger fans as compared to the smaller fans typically found in servers. Server Load Balancing By modifying the workload of various servers 105 within a data room 110 , a load balancer 160 dynamically adjusts the number of requests processed by various servers to avoid large variations in the temperature of different servers which reduces or eliminates the need for internal fans to cool the server 105 , at least under normal operating conditions. For multiple servers in the data room 110 , the load balancer includes data associating a number of requests for processing by a server 105 , or a “server workload,” with a pressure difference between a cold aisle 110 and a hot aisle 120 in the data room 100 . FIG. 2A shows one example of a load balancing table 200 maintained by the load balancer 160 . In one embodiment, the load balancer 160 includes a load balancing table 200 associated with each server 105 in a data room 100 , allowing modification of individual server workload. In another embodiment, the load balancer 160 includes load balancing tables 200 associated with various groupings of servers, so that the workload of different groups of servers is modified by the load balancer 160 . For example, different load balancing tables 200 are associated with different types or configurations of servers, allowing modification of the workload of multiple types or configurations of servers. For purposes of illustration, the example load balancing table 200 shown in FIG. 2A associates a pressure difference between the cold aisle 110 and the hot aisle 120 with a server workload, such as a number of requests per second. This allows the load balancing table 200 to identify a maximum server workload for a particular pressure difference. Each entry in the load balancing table 200 identifies a maximum server workload for a specified pressure difference. When the load balancer 160 receives a pressure difference from one or more sensors 117 , the load balancer 160 determines the maximum workload for a server 105 at the received pressure difference and directs requests to different servers 105 based on the maximum server workload for the received pressure difference. For example, the load balancer 160 allocates received requests to different servers 105 so that multiple servers 105 operate at their maximum workload for the received pressure difference. For purposes of illustration, the example load balancing table 200 shown in FIG. 2A includes data associated with a single server 105 ; however, in other embodiments, the load balancing table 200 may include data associated with different groups of servers. For example, the load balancing table 200 may include data associated with different models, or types, of servers. As shown in the example of FIG. 2A , in addition to data associating workload with a pressure difference, the load balancing table 200 may also include additional data. For example, the load balancing table 200 may identify the server power and the cubic feet per minute of air flowing from the cold aisle 110 to the hot aisle 120 at different pressure differences. This additional information may be used to determine server 105 and/or data room 100 characteristics at various combinations of server workloads and data room pressure differences. FIG. 2B graphically illustrates use of the load balancing table 200 to determine server workload based on the pressure difference between the cold aisle 110 and the hot aisle 120 of the data room 110 . For purposes of illustration, FIG. 2B shows a graph illustrating server workload against pressure difference is shown for three servers 210 A, 210 B, 210 C. After receiving data describing a pressure difference 220 between the cold aisle 110 and the hot aisle 120 from one or more sensors 117 in the data room 100 , the load balancer 160 identifies server workloads associated with the pressure difference 220 . As shown in FIG. 2B , at the pressure difference 220 , a first server 210 A has a first maximum workload 230 while a second server 210 B and a third server 210 B have a second maximum workload 230 B and a third maximum workload 230 C, respectively. Based on the maximum workload 230 A, 230 B, 230 C of the servers 210 A, 210 B, 210 C, the load balancer 160 allocates requests to each of the servers 210 A, 210 B, 210 C. For example, based on the maximum workload 230 A, 230 B, 230 C, the load balancer 160 modifies the workload of each server 210 A, 210 B, 210 C so that each server operates at, or near, the maximum workload 230 A, 230 B, 230 C. In one embodiment, the load balancer 160 directs received requests to the servers 210 A, 210 B, 210 C to increase the number of requests processed by each server 210 A, 210 B, 210 C until each server 210 A, 210 B, 210 C is operating at its maximum workload 230 A, 230 B, 230 C. For example, the load balancer 160 directs requests to the first server 210 A until the a first server 210 A is operating at its maximum workload 230 A or at a fraction of its maximum workload 230 A then directs requests to the second server 210 B or the third server 230 C. In the example of FIG. 2B , at the pressure difference 220 , the third workload 230 C of the third server 210 C is larger than the first workload 210 A of the first server 210 A, allowing the third server 210 C to process more requests at the pressure difference 220 . This allows the load balancer 160 , at the pressure difference 220 , to allocate requests so that the third server 210 C receives a greater number of requests than the first server 210 A. Thus, by modifying the server 210 A, 210 B, 210 C used to process requests, the load balancer 160 allows each server 210 A, 210 B, 210 C to operate at maximum performance by maximizing the number of requests processed by each server 210 A, 210 B, 210 C at a particular pressure difference 220 . In one embodiment, when each server 210 A, 210 B, 210 C is processing the maximum number of requests at a pressure difference 220 and the load balancer 160 receives additional requests, the load balancer 160 communicates a control signal to the control system 150 so that the exhaust unit 125 draws more heated air from the hot aisle 120 . This increases the pressure difference between the cold aisle 110 and the hot aisle 120 . Pressure in the cold aisle 110 may also be increased by increasing the supply of air from the cold air supply 115 . Based on the increased pressure difference, the load balancer 160 allocates the additional requests so that different servers 210 A, 210 B, 210 C have their maximum workload at the increased pressure difference. SUMMARY The foregoing description of the embodiments of the invention has been presented for the purpose of illustration; it is not intended to be exhaustive or to limit the invention to the precise forms disclosed. Persons skilled in the relevant art can appreciate that many modifications and variations are possible in light of the above disclosure. Some portions of this description describe the embodiments of the invention in terms of algorithms and symbolic representations of operations on information. These algorithmic descriptions and representations are commonly used by those skilled in the data processing arts to convey the substance of their work effectively to others skilled in the art. These operations, while described functionally, computationally, or logically, are understood to be implemented by computer programs or equivalent electrical circuits, microcode, or the like. Furthermore, it has also proven convenient at times, to refer to these arrangements of operations as modules, without loss of generality. The described operations and their associated modules may be embodied in software, firmware, hardware, or any combinations thereof. Any of the steps, operations, or processes described herein may be performed or implemented with one or more hardware or software modules, alone or in combination with other devices. In one embodiment, a software module is implemented with a computer program product comprising a computer-readable medium containing computer program code, which can be executed by a computer processor for performing any or all of the steps, operations, or processes described. Embodiments of the invention may also relate to an apparatus for performing the operations herein. This apparatus may be specially constructed for the required purposes, and/or it may comprise a general-purpose computing device selectively activated or reconfigured by a computer program stored in the computer. Such a computer program may be stored in a tangible computer readable storage medium, which include any type of tangible media suitable for storing electronic instructions, and coupled to a computer system bus. Furthermore, any computing systems referred to in the specification may include a single processor or may be architectures employing multiple processor designs for increased computing capability. Embodiments of the invention may also relate to a computer data signal embodied in a carrier wave, where the computer data signal includes any embodiment of a computer program product or other data combination described herein. The computer data signal is a product that is presented in a tangible medium or carrier wave and modulated or otherwise encoded in the carrier wave, which is tangible, and transmitted according to any suitable transmission method. Finally, the language used in the specification has been principally selected for readability and instructional purposes, and it may not have been selected to delineate or circumscribe the inventive subject matter. It is therefore intended that the scope of the invention be limited not by this detailed description, but rather by any claims that issue on an application based hereon. Accordingly, the disclosure of the embodiments of the invention is intended to be illustrative, but not limiting, of the scope of the invention, which is set forth in the following claims.

4y

TECHNICAL FIELD OF THE INVENTION The present invention is directed to the production of arterial grafts, and, more particularly, to a method of producing storable, surgically-ready protein-impacted grafts. BACKGROUND OF THE INVENTION Human blood vessels damaged beyond repair by disease or injury are typically replaced with artificial blood vessels, commonly known as vascular grafts. Most grafts in use today are porous in nature, being typically formed of knitted or woven fibers. However, in order for the porous graft to conduct fluid without leaking, it must be impregnated with a material that ensures hemorrhage-free conduction of blood. One proposed method for forming an artificial vascular graft is disclosed in U.S. Pat. No. 4,842,575. As taught therein, an aqueous slurry of collagen fibrils is deposited in the lumen of a previously prepared graft and manually massaged to ensure intimate mixing of the collagen into the porous structure of the graft substrate. After massaging, the collagen is dried and cross-linked by exposure to a formaldehyde vapor. This procedure is repeated as necessary to ensure a blood-tight graft. There are numerous drawbacks to grafts produced by this method. First, grafts produced by manual massaging will have an uneven distribution of collagen throughout the graft walls, resulting in uneven porosity. This requires repeated applications by manual massaging, typically six applications, according to the teachings of the patent. In addition, these grafts may have excess collagen deposited throughout the interior wall of the graft, yielding an uneven flow surface. This can result in excess collagen being carried away by the blood flow, and can cause postsurgical complications. Hence, this method lacks the ability to control the internal wall flow surface characteristics and does not provide consistent uniformity in each graft. Because this method is labor intensive, it is slow, inefficient, and unreliable. Consequently, there is a need for a method of efficiently producing storable, surgically-ready, protein-impacted grafts that enables reliable control over the rate and direction of impaction. SUMMARY OF THE INVENTION The present invention is directed to a method of producing a storable, surgically-ready protein-impacted material, ideally a vascular graft. The method comprises the steps of soaking an untreated graft in a flow of protein suspension, preferably a collagen suspension, fixing the collagen in the graft, softening the collagen-impacted graft in a softening solution, and air-drying the protein-impacted graft prior to packaging. While collagen will be used herein as the preferred protein, it is to be understood that the invention has applicability to other proteins, as will be described more fully below. In accordance with another aspect of the present invention, the step of soaking the graft in a flow of collagen suspension includes the step of preparing a buffer solution comprised of 0.5% to 25% weight/volume (w/v) sodium chloride and 0.5% to 25% w/v sodium acetate in aqueous solution. A collagen suspension is then prepared by mixing 1% to 7% w/v collagen, ideally a Type 1 Bovine Fibrous Collagen with the buffer solution. Preferably, the mixture is blended for at least 4 minutes then set aside until the collagen suspension and foam are separated, after which the collagen suspension is collected. It is to be understood that other proteins may be used, such as 1% to 10% w/v gelatin. In addition, 0.3% to 25% w/v albumin may be added to the collagen, gelatin or a mixture of collagen and gelatin. In accordance with yet another aspect of the present invention, the step of soaking the graft comprises mounting the graft in a reactive tube and subjecting the graft to a flow of heated water and then to a flow of collagen suspension at an elevated temperature and at a pressure differential between the inside and outside wall surfaces that forces the collagen suspension into the walls of the graft. In accordance with still yet another aspect of the present invention, the collagen is thermally fixed on the exterior surface of the collagen-impacted graft by placing the graft in a refrigerator or freezer and exposing the graft to subfreezing temperatures to gel the collagen impacted in the graft. Ideally, the graft is placed in the freezer for approximately ten minutes. In accordance with yet another aspect of the present invention, the collagen is chemically fixed in the collagen-impacted graft by subjecting the graft to a cross linking agent, such as various aldehydes, for a predetermined period of time, preferably by soaking the graft in a formaldehyde solution having a concentration of 0.5% to 20% volume/volume (v/v) for at least one hour. In accordance with a further aspect of the present invention, the graft is softened by soaking in a solution of alkyl alcohol containing at least two hydroxyl groups, preferably glycerin, for a predetermined period of time, preferably at least one hour. The glycerin can be diluted with water to concentrations exceeding 10% v/v. In accordance with yet a further aspect of the present invention, after rinsing and soaking in the glycerin solution, the collagen-impacted graft is air-dried for a predetermined period of time, preferably at least 12 hours. The preferred methodology for such prosthesis may additionally comprise the step of treating the prosthesis with a glycine solution prior to the drying procedure. The glycine solution is preferably a 1% to 10% w/v aqueous solution. As will be readily appreciated from the foregoing description, the present invention does not require any presoaking of the graft prior to placement in a soaking apparatus. This saves time as well as the cost of the chemicals. Mechanically impacting the graft with a dynamic flow of protein suspension enables more precise control of the amount of protein impregnated in the graft walls. In addition, a smooth inner wall surface of consistent quality is formed in each succeeding graft produced because the process is easily automated. Furthermore, thermal fixation enables soaking the graft in a formaldehyde solution without having the impacted protein washed out. This avoids the use of formaldehyde vapor, which is difficult to work with and requires a special apparatus to treat the materials. Finally, the protein suspension can be used again to treat additional grafts. Accordingly, the present invention provides a controllable, reliable and efficient method of producing protein-impacted grafts with very low water permeability that are storable in a surgically-ready state. BRIEF DESCRIPTION OF THE DRAWINGS The foregoing features and advantages of the present invention will be more readily appreciated as the same becomes better understood from the detailed description of the preferred embodiment when taken in conjunction with the following drawings, wherein: FIG. 1 is a schematic representation of the method of producing a protein-impacted graft in accordance with the present invention; and FIG. 2 is a partial cross-sectional view of a graft soaking in a flow of collagen suspension inside a reactive tube. DETAILED DESCRIPTION In accordance with the method of the present invention, an untreated graft is impregnated with a protein, packaged, and sterilized for later use during surgery. Because these grafts are well known in the art and commercially readily available, they will not be described in detail herein. Briefly, these grafts are typically porous because they are constructed of fibrous material to enhance bonding with living tissue. As a result of this porosity, it is necessary to impregnate the graft with a material that enables the graft to provide a leak-proof conduit for blood. It is to be understood that while the following description denotes certain quantities in connection with the preparation of a protein impregnated graft, these quantities may be varied proportionately to enable preparation of more grafts. In addition, while the following description recites the use of a collagen suspension, it is to be understood that other proteins may be used, such as gelatin, or a mixture of gelatin and collagen. A mixture of albumin with collagen and/or gelatin in predetermined proportions can also be used. Referring initially to FIG. 1, in accordance with a preferred method 10 of the present invention of producing a protein-impacted graft, a buffer solution 12 is first prepared. The preparation of the buffer solution 12 requires mixing 0.5% to 25% w/v sodium chloride with 0.5% to 25% w/v sodium acetate in an aqueous solution. This solution can be stored at room temperature for at least a week. In the next step, a protein suspension 14 is prepared. Ideally, 1% to 7% w/v of Type 1 Bovine Fibrous Collagen is combined in the buffer solution in a blender for at least 4 minutes or until a homogenous suspension is formed. While this may involve an increase in temperature during the mixing or homogenization process, this temperature increase is acceptable. The collagen suspension is transferred to a beaker and placed in a water bath at 35 to 40 degrees Centigrade. The mixture is left undisturbed for the collagen suspension and foam to separate. When separation is complete, the collagen suspension is collected and placed in another beaker. The collagen suspension can be stored in a sterile environment at 35±10% degrees Centigrade for no more than 48 hours or it can be frozen and liquified before use. Mounting 16 and soaking 24 of the graft 22 will now be described in conjunction with FIG. 2. Illustrated in FIG. 2 in cross section is a reactive tube 18 that has a longitudinal axial bore 20. Mounted in the bore 20 is an untreated prosthesis or artificial graft 22, also shown in cross section. Ideally, the graft 22 is a straight graft, 6 or 8 millimeters in diameter, that is readily commercially available and will not be described in detail herein. In the step of mounting 16 the graft 22, one end of the graft 22 is secured so that the graft 22 hangs in a vertical position. Preferably, a 400 gram weight is attached to the free end of the graft 22 to stretch the material of the graft 22. The graft 22 is measured to 35.5 inches from the clamped end and the excess material is detached. Typically, most mechanical perfusion devices can handle up to twelve grafts, which should all be measured and cut in the manner described above. The internal assembly of the reactive tube 18 is removed from the apparatus and each graft 22 is loaded into a reactive tube 18 according to conventional procedures. The graft 22 and reactive tube 18 are secured back in the apparatus prior to operation. Initially, water is pumped through the graft to open the pores or interstices of the graft wall. The temperature of the water is held in the range of 50-65 degrees Centigrade. After a predetermined period of time, the water is drained and replaced with the collagen suspension which is heated in the range of 38-40 degrees Centigrade. The graft is soaked in a flow of the previously prepared collagen suspension until it is completely saturated to complete the dynamic soaking process 24. As shown in FIG. 2, the velocity of the internal flow V int of collagen suspension in the graft 22 generates an internal force F int having force component Fn int normal to the interior of the graft wall that is less than the external force component Fn ext normal to the exterior of the graft wall generated by the velocity V ext of an external flow of collagen suspension which forces the suspension into the walls from the inside out. This simulates the flow of blood through the graft and enables control of the quality of the internal wall. The fixation process 26 comprises two general steps, thermal fixing and chemical fixing. In the thermal fixation process, the collagen-impacted graft is removed from the reactive tube 18 and placed in a freezer where it is exposed to subfreezing temperatures. This causes the exterior of the collagen to gel and thereby hold the collagen in place in the interstices of the graft walls and prevent it from being washed out during the chemical fixation process. Ideally, the graft is exposed to the subfreezing temperatures for approximately ten (10) minutes. Once thermal fixation is complete, a formaldehyde solution 28 is prepared for the chemical fixation step. The formaldehyde solution preferably has a concentration of 0.5% to 20% v/v in aqueous solution. If necessary, this solution can be stored at room temperature for at least a week. The graft 22 is placed in sufficient formaldehyde solution to completely cover the graft. The graft is permitted to soak for a predetermined period of time, preferably at least one to three hours. The chemically-fixed collagen-impacted grafts are then removed from the formaldehyde solution and subjected to a water wash 30. This wash is conducted in a laminar flow hood using aseptic technique. The graft is placed in a sterile container and rinsed with sterile water. Enough sterile water is then added to cover the grafts and the container is closed. The grafts then soak for a predetermined period of time, preferably at least one to two hours. A glycine solution 32 is then prepared consisting of 1% to 10% w/v aqueous solution. The glycine solution should be used within one (1) week after the preparation date. In the glycine wash procedure 34, a laminar flow hood using aseptic technique is used. The washed grafts are placed in a sterile container and the glycine solution is added to cover the grafts. The grafts are rinsed and the solution is drained out of the container. The grafts are then covered with a glycine solution and again allowed to soak, this time for at least one to three hours. To be sure that all free aldehyde groups are removed during the washing and soaking steps, a sterile syringe is used to draw out approximately a 10 mL sample of the glycine solution, which sample is then checked for the absence of free aldehydes. Assuming the absence of free aldehyde groups, the grafts are then stored in a sterile container. In the plastification procedure 36, the grafts are first softened by soaking in a glycerin solution. Glycerine solution 37 preparation can be accomplished by mixing glycerin with sterile water. The glycerin solution may be diluted with water to a concentration of at least 10% v/v. This solution can be stored at room temperature for at least a week. The grafts are rinsed with sterile water, placed in a sterile container, and enough glycerin is added to cover the grafts. The grafts are allowed to soak for a predetermined period of time, preferably at least one to three hours. In the final air drying process 38, the grafts are removed from the glycerin solution and gently shaken to remove residual glycerin. The grafts are then placed in a sterile environment and allowed to air dry for a predetermined period of time, preferably at least ten to twelve hours. After each graft has dried, it is placed in a package for sterilization, and stored. While a preferred embodiment of the invention has been illustrated and described, it is to be understood that various changes may be made therein without departing from the spirit and scope of the invention. For instance, the glycine wash may be omitted, if desired. In addition, the dynamic soaking process may consist of subjecting the graft to only an internal flow of protein suspension. This will still force the suspension into the graft walls from the inside out. Finally, other porous materials such as flat sheets may be prepared with this method by simultaneously subjecting it to a different flow rate on each side to control the rate and direction of impaction. Consequently, the invention is to be limited only by the scope of the claims that follow.

4y

BACKGROUND OF THE INVENTION The present invention relates to a spherical bearing for use in, for instance, transmission and steering wheel portion of an automobile, and a link motion mechanism of various automation machines, and more particularly to an oilless spherical bearing and a method of production thereof. Hitherto, as a spherical bearing of this type, for instance, one shown in FIG. 11 is known (refer to the Japanese Patent Publication No. 42569/1976). Referring to FIG. 11, an inner ring 100 has an outer peripheral surface formed spherically, and the inner ring 100 is slidably fitted with an outer ring 101 whose inner peripheral surface is similarly formed spherically. In addition, a liner 102 formed of fluoride resin or the like is interposed between the inner ring 100 and the outer ring 101 to realize an oilless spherical bearing. As illustrated in FIG. 12, such a spherical bearing is arranged as follows. The surface of the inner ring 100 is coated with a self-lubricating thin plate 103 formed of a low-friction high-polymer material, and the thus prepared inner ring 100 is accommodated in a mold 104 like a core, the mold 104 having a configuration that matches with that of the outer ring 101. A low-melting-point alloy is cast into a cavity therebetween, which completes the formation of the outer ring 101 and, at the same time, the assembly. In addition, sliding surfaces are formed between an outer surface of the inner ring 100 and the above-described self-lubricating thin plate 103 secured to the outer ring 101 at the time of casting. Furthermore, since the free rotation of the inner ring 100 is hampered as a result of the shrinkage of the outer ring 101 during cooling and hardening, the outer ring 101 is compressed in the axial direction after casting, as shown in FIG. 13, so that the outer ring 101 is subjected to slight plastic deformation in the form of a chevron in which a central part thereof is bent in terms of its vertical cross section, and a slight gap required is hence formed between the thin plate 103 and the inner ring 100. In such a prior art, however, bonding between the self-lubricating thin plate 103 and the outer ring 101 is effected by fusing the surface of the thin plate 103, which is brought into contact with the molten metal during casting, to the inner surface of the outer ring 101 by means of heat thereof. However, the affinity between resin and metal is generally poor, the bonding strength is weak if they are simply fused to each other, and there is a possibility that the thin plate 103 may become exfoliated due to a shearing force acting on the bonded surfaces, causing the position of the thin plate 103 to be offset. When the position of the thin plate 103 is offset, the metal surface of the outer ring 101 is exposed, and the metallic portion is brought into direct contact with the inner ring 100, which results in increased sliding resistance and causes rattling due to the partial wear of the sliding surface. In addition, since the liner 102 is formed of a resin, the compressive strength thereof is low, and has the possibility of becoming damaged if the compressive load applied to the inner ring 100 becomes large. Moreover, even if damage does not result, there is a problem in that crip deformation may occur, making it impossible to bear a large load. Furthermore, since the fluoride-based resin has a small conductivity, the fluoride-based resin is unable to allow the heat generated by friction with the inner ring 100 during use to escape effectively, so that there has also been the problem of the sliding surface becoming overheated and seized. Meanwhile, in production, the thin plate 103 is coated on the surface of the inner ring 103, but, during casting of the outer ring 101, it is necessary to prevent the molten metal from flowing to the side of the inner ring 100. Namely, if the molten metal enters between the thin plate 103 and the inner ring 100, the molten metal hardens, with the result that a metallic foreign substance is interposed between the thin plate 103 and the inner ring 100 and the surface of the inner ring 100 becomes worn by the metallic foreign substance during use. In addition, the thin plate 103 also becomes damaged by wearing powders, so that the characteristics of the bearing are lost. This problem would be satisfied with a technique that the thin plate 103 is held in close contact with the outer surface of the inner ring 100 during casting, but since the outer surface of the inner ring 100 is spherically shaped, it has been difficult in terms of molding to hold the sheet-like thin plate 103 in close contact with such a spherical portion. For instance, even if the thin plate 103 is formed into a spherical shape in advance, if an attempt is made to insert the inner ring 100 into such a spherically formed one, the inner ring 100 cannot be inserted since its central portion is expanded. If an attempt is made to insert it forcedly, there has been the problem that the thin plate 103 becomes broken. In addition, if the thin plate 103 is formed into the shape of a strip and if the thin plate 103 is wound around the outer surface of the inner ring 100, and the both ends of the wound thin plate 103 are provisionally attached to each other by means of an adhesive tape, there has been the problem that the molten metal flows round to the side of the inner ring 103 from the seam of the thin plate 103. On the other hand, in a conventional example, since a very small gap is formed between the thin plate 103 and the inner ring 100 by applying an axial external force to the shrunk outer ring 101, it has been impossible to form this small gap uniformly. In other words, the outer ring 101 has been bent into the chevron shape by an external force, the very small gap is large at the central portion of the inner peripheral surface of the outer ring 101 and is small at edge portions 101a,101a. For that reason, the swinging resistance of the inner ring 100 becomes nonuniform, and the smooth movement of the inner ring 100 is hampered. In addition, since the gap is nonuniform, the edge portions of the thin plate 103 are partially brought into contact with the outer surface of the inner ring 100 when the load is applied. As a result, the contact area between the thin plate 103 and the inner ring 100 is narrowed, and a concentrated load is applied to the vicinity of the edge portions, making it impossible to bear a high load. In addition, there have also been such problems that partial wear is likely to occur at the edge portions, resulting in play. Furthermore, it has been unavoidable to increase the very small gap in order to prevent the partial contact between the thin plate 103 at the edge portions 101a,101a and the inner ring 100, so that there has been another problem that this results in a weakness against an impact load as well as a large amount of play, possibly causing a delay in the transmission of a force in, for instance, a link mechanism. SUMMARY OF THE INVENTION Accordingly, an object of this invention is to substantially eliminate defects or drawbacks encountered to the conventional technique described above and to provide an improved spherical bearing capable of increasing the bonding strength between a liner and an outer ring, increasing the strength of the liner itself and making uniform a small gap between the liner and the inner ring. Another object of this invention is to provide an improved spherical bearing which facilitates a molding process for forming the same, has a good heat conductivity and a long life and makes it possible to prevent molten metal from flowing round to the side of the inner ring. A further object of this invention is to provide a method of manufacturing a spherical bearing of the superior characteristic features described above. These and other objects can be achieved according to this invention in one aspect by providing a spherical bearing comprising an outer ring, an inner ring located inside the outer ring to be slidable, and a liner disposed between the outer and inner rings, the liner comprising a liner body made of resin and a metallic mesh member embedded in the liner body, the metallic mesh member partially biting an inner peripheral portion of the outer ring so as to achieve firm engagement of the liner with the outer ring. In another aspect of this invention, there is provided a method of manufacturing a spherical bearing in which an inner ring is slidably fitted in an outer ring through a liner comprising the steps of coating an outer surface of the inner ring to be coated with a resin made sheet, embedding a metallic mesh member in the coated resin made sheet, disposing the inner ring in a mold, preparing a molten metal and casting the molten metal around the resin-made sheet coated on the inner ring to mold the outer ring, filling the molten metal in meshes of the mesh member so as to bond the resin-made sheet to the outer ring, and pressing the outer ring against an outer surface of the inner ring and spreading the same by applying a radially inwardly-oriented external force to the outer ring of a molding removed from the mold after cooling and hardening, thereby forming a very small gap between the resin-made sheet bonded to an inner periphery of the outer ring and the outer surface of the inner ring. According to the spherical bearing of the character described above and the method of manufacturing the same, the liner is firmly bonded to the outer ring by means of the mesh member and is not exfoliated by frictional resistance or the like during use. In addition, the strength of the liner is reinforced by the metallic mesh member, and the mesh member functions as a core and permits molding into a desired shape. Furthermore, the frictional heat during use is allowed to escape through the mesh member, and the sliding surface of the inner ring is cooled effectively. Moreover, even if a resin portion of the liner becomes worn and the mesh member is exposed as a result, favorable self-lubricating function is maintained since the meshes of the mesh member are filled with the resin. Meanwhile, since the sheet made of the resin is held in close contact with the outer surface of the inner ring due to the deformation of the mesh member before casting of the outer ring, the molten metal does not enter between the inner ring and the sheet. In addition, if the outer ring which has shrunk after cooling and hardening is spread by applying an external force thereto inwardly in the radial direction, the inner periphery of the outer ring is spread along the outer surface of the inner ring, and the mesh member bonded to the inner periphery of the outer ring expands by a portion in which the outer ring has been spread. Furthermore, as the mesh member is expanded, the resin portion of the resin-made sheet is also stretched, so that a uniform, very small gap is formed between the resin-made sheet and the outer surface of the inner ring over the entire periphery thereof. The preferred embodiments of this invention will be described in detail hereunder with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS In the accompanying drawings: FIG. 1 is a vertical cross-sectional view of a spherical bearing in accordance with an embodiment of the present invention; FIG. 2 is an enlarged cross-sectional view of a bonded portion between a liner and an outer ring both shown in FIG. 1; FIG. 3 is a perspective view of the liner taken out; FIG. 4 is a schematic perspective view of the bearing shown in FIG. 1; FIG. 5 is a vertical cross-sectional view of an inner ring; FIGS. 6A and 6B are views illustrating a resin-made sheet to be preprocessed; FIG. 7 is a vertical cross-sectional view illustrating a mouth portion to be throttled of the resin-made sheet coated on the inner ring; FIG. 8 is a vertical cross-sectional view of the inner ring for which the mouth-portion throttling process has been completed; FIG. 9 is a schematic vertical cross-sectional view of a mold in a casting process; FIG. 10 is a schematic vertical cross-sectional view of the bearing in a gap forming process after casting; FIG. 11 is a vertical cross-sectional view of a conventional spherical bearing; FIG. 12 is a vertical cross-sectional view of the mold in a process of casting the outer ring of the bearing of FIG. 11; and FIG. 13 is a schematic vertical cross-sectional view of the apparatus illustrating a process of forming a very small gap after the casting of the outer ring of FIG. 12. DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereafter, the present invention will be described on the basis of an embodiment illustrated in the accompanying drawings. FIGS. 1 to 4 illustrate a spherical bearing in accordance with an embodiment of the present invention. In the drawings, an inner ring 1 has an outer surface formed into the form of a spherical strip, and the inner ring 1 is slidably engaged with an inner periphery of an outer ring 3 via a liner 2. The inner ring 1 is spherically shaped, and a through hole 4 for mounting a journal therein is formed in the direction of a central axis thereof. Meanwhile, the outer ring 3 has a configuration of a flat cylinder, and its inner peripheral surface is formed into a spherical shape whose diameter is slightly larger than that of the above-described inner ring 1. In addition, the liner 2 is a cylindrical member which is expanded into the shape of a spherical strip matching with the configuration of the inner periphery of the above-described outer ring 3, and is constituted by a liner body 21 made of resin and a metallic mesh member 22 embedded in this liner body 21. As the liner body 21, a resin which has a low coefficient of friction and excels in frictional resistance and also excels in heat resistance is employed. In this embodiment, a fluoride-based resin such as tetrafluoroethylene resin is used, which has a high load resistance and a large thermal conductivity in addition to the aforementioned characteristics, and its coefficient of thermal expansion is small. In addition, as the mesh member 22, bronze, stainless steel, or the like which is flexible and rigid is used. As for a state in which the mesh member 22 is embedded, the mesh member 22 is embedded in such a manner that a sliding surface side S which is brought into contact with the inner ring 1 has a thick resin portion, while the side of its surface contacting the outer ring 3 is thin. Meanwhile, the inner surface of the outer ring 3 is joined to the liner 2 in a state in which the inner surface bites into the inside of the meshes 22a of the aforementioned mesh member 22. As for the mesh member 22, wires constituting the same are welded together at a seam, and the meshes do not become loose even if a high load (4,000 kg/cm 2 or thereabout) is applied thereto, and the mesh member 22 firmly binds and holds the resin layer to prevent the deformation or flow thereof. In addition, the mesh member 22 has a property of speedily radiating heat which is generated on the surface of the bearing. A method of producing the spherical bearing having the above-described arrangement will be described with reference to FIGS. 5 to 10. First, the inner ring 1 is produced, as shown in FIG. 5. The inner ring 1 is finished after quenching, and a spherical portion la is finished by lapping. The process of coating with a sheet 5 made of a resin will be described with reference to FIGS. 5 to 8. First, the resin-made sheet 5 is formed in advance into a cylindrical shape, as shown in FIG. 6A. Next, the resin-made sheet 5 is cut in round slices at predetermined widths by a portion to be coated on the inner ring 1, and this portion is applied on the outer surface of the inner ring 1. Further, as shown in FIG. 7, both end portions of the sheet 5 are throttled by using press dies 6, 7, and, as shown in FIG. 8, the sheet 5 is made to be closely adhered to the outer surface of the inner ring 1 over the entire periphery thereof. Furthermore, as shown in FIG. 9, the inner ring 1 is inserted into a mold 8 and die casting is effected. The mold 8 is a split type to be splittable into two parts along a perpendicular line Y which passes through a central point O of the inner ring 1 and is perpendicular to a central axis X thereof. Inside the mold 8, an annular empty chamber 9 for forming the outer ring 3 is formed around the inner ring 1, and the outer ring 3 is formed as molten metal is poured from a casting channel 10 which communicates with this empty chamber 9. As for the molding material of the outer ring 3, zinc (melting point: 400° C.), aluminum (melting point: 600° C.), or the like is used. It should be noted that a specific alloy for a bearing may not be used as the material of the outer ring 3. According to the present invention, since the resin-made sheet 5 is held in close contact with the outer surface of the inner ring 1 in a preprocessing process, it is possible to completely prevent the molten metal from flowing round from the end portions of the sheet 5 to the side of the inner ring 1 during casting. Owing to the heat of the molten metal poured, the contact surfaces of the resin sheet 5 and the molten material are fused by the heat, and the metal enters the meshes 22a of the mesh member 22, with the result that the sheet is firmly bonded to the inner peripheral surface of the outer ring 3. Subsequently, after the internal molten material has been cooled and hardened, the mold is opened to take out the molded product. Furthermore, after the molded product is removed from the mold 8, the shrunk outer ring 3 is spread by applying an external force to the outer periphery thereof inwardly in the radial direction, as shown in FIG. 10, so as to form a very small gap d between the sheet 5 and the outer surface of the inner ring 1. Namely, the inner surface of the outer ring 3 is pressed against the outer surface of the inner ring 1 by the external force, so that the inner surface of the outer ring 3 is spread by conforming to the outer spherical surface of the inner ring 1. The mesh member 22 bonded to the inner peripheral surface of the outer ring 3 is expanded by the portion in which the outer ring 3 has spread, and the resin portion of the resin-made sheet 5 is also spread by the spreading of the mesh member 22, so that the very small gap d with a uniform width is formed between the resin-made sheet 5 and the outer surface of the inner ring 1 over the entire periphery thereof. Finally, the outer peripheral surface and the both end surfaces of the outer ring 3 are subjected to cutting to remove flashes and the like, and surface finishing is provided, thereby completing the processing. According to the thus formed spherical bearing, since the metal for the outer ring 3 bites into the meshes 22a of the mesh member 22 of the liner 2, the resin-made sheet 5 does not become offset by the pressure or movement of the pressure molten metal, and the liner 2 can be formed at a predetermined position of the outer ring 3 with a high degree of accuracy. In addition, since the liner 2 is thus bonded firmly, there is no possibility that the liner 2 is offset with respect to the outer ring 3 or removed by a shearing force acting on the bonding portion when the spherical bearing is used under high load and at high speed. Meanwhile, even if a large load is applied from the inner ring 1 to the liner 2, since the liner 2 is reinforced by the metallic mesh member 22, the liner 2 is not crushed by a compressive load. In addition, the creep deformation of the resin portion is prevented by the location of the mesh member 22. The frictional heat generated on the bearing surface during use is allowed to escape to the outer ring through the metallic mesh member 22, and the sliding portion is cooled efficiently. Furthermore, even if the resin portion of the liner 2 becomes worn and the mesh member 22 is exposed as a result, since the meshes 22a are filled with the resin, the resin powders loaded in the meshes 22a are the mesh member, the bonding strength can be made far stronger than a case where a resin-made thin plate is directly fused to the outer ring, as in the conventional case, and the reliability can be enhanced. In addition, since the liner itself is reinforced by the mesh member, its strength is high, and its load resisting capability can be improved. Furthermore, the heat generated on the bearing surface during use is transmitted speedily from the mesh member to the outer ring, and the cooling efficiency of the bearing can be enhanced. Moreover, even if the resin portion of the liner becomes worn, the resin powders loaded in the meshes of the mesh member are spread in the form of a film over the entire sliding surface as a lubricant, so that the lubricating performance can be maintained and a long life can be ensured. Meanwhile, in the present invention, since a resin-made sheet is applied to the spherical surface of the inner ring in a closely adhered state prior to the casting of the outer ring, it is possible to completely prevent the molten metal from flowing round to the side of the inner ring during the casting of the outer ring, it is possible to protect the sliding surfaces of the liner and the inner ring, and the reliability of the product can be improved. In addition, as an external force is applied to the outer ring inwardly in the radial direction, it is possible to spread in the form of a film as a lubricant over the entire sliding surface during the rotation of the inner ring 1, so that a favorable self-lubricating function is maintained. Furthermore, since the gap d between the liner 2 and the inner ring 1 is formed by compressing the outer ring 3 inwardly in the radial direction and by spreading the outer ring 3 by conforming with the outer peripheral surface of the inner ring 1, a uniform size is obtained over the entire sliding surface. Accordingly smooth movement of the inner ring 1 is ensured, and since the contacting area is large, it is possible to bear a high load, and the load resisting capability is kept to be high. In addition, partial wear does not occur, and it is hence possible to prevent rattling or the like resulting from the partial wear. It should be noted that, although, in the present invention, a description has been given of a spherical bearing having a cylindrical outer ring, the present invention is also applicable to one having a rod, as in the case of a conventional example, i.e., a rod end bearing. The present invention is constituted by the above-described arrangement and operation, and since a liner is bonded to an outer ring by using a liner with a metallic mesh member embedded therein and by embedding the inner peripheral surface of the outer ring in the meshes of uniformly form the very small gap formed between the resin-made sheet and the inner ring, so that smooth movement of the inner ring can be ensured. Also, since the inner ring is not brought into partial contact with the liner, it is possible to provide large contacting areas, making it possible to increase the load resisting capability and to prevent the occurrence of partial wear. In addition, since the very small gap can be made uniform, the size of the gap can be made as small as possible. This results in improved shock resistance and smaller play between the inner ring and the liner, and it is possible to improve the response characteristics of transmission of a force when the spherical bearing is used in, for instance, a link mechanism. Thus, the present invention makes it possible to obtain various effects.

4y

BACKGROUND OF THE INVENTION This invention relates to maintenance-free, non-pneumatic vehicle and cart tires, particularly intended for wheelchairs, pushchairs, tricycles, bicycles, trollies, carts, and gurneys. Non-pneumatic tires offer important maintenance advantages over pneumatic tires. With non-pneumatic tires there is no need to check and adjust air pressure and there is never a worry about a flat or punctured tire, thus avoiding these common inconveniences encountered when using pneumatic tires. Especially for persons using wheelchairs, surveys show that tires are the biggest repair problem for all kinds of wheelchairs, see "Wheelchair III: Report of a Workshop" Bethesda, Md.: Rehabilitation Engineering Society of North America, 1982. Solid and foamed rubber tires, which do not contain air under pressure, do not become dysfunctional when punctured. Here, the use of the word `rubber` is intended to cover that group of materials which has the ability to undergo large deformations and to recover quickly. However, solid rubber tires are extremely heavy, with a high rolling resistance, and have a very high spring constant, giving an uncomfortable ride. Foamed rubber tires offer improvements over solid rubber tires but are prone to cutting and destruction by fatigue failure due to the very low fatigue strength associated with foamed materials: Atkins, A. G., and Y-W Mai, `Elastic and Plastic Fracture`, E. Horwood Ltd., 1985, (p. 799). All conventional tires, including standard pneumatic tires, are made in standard vulcanizing moulds, and a special mould is required for each size of tire. In addition, there are expensive complications in the moulding process such as mould cores and reinforcement materials being required. U.S. Pat. No. 4,493,355 issued to Ippen et al., and assigned to Bayer Aktiengesellschaft, (hereafter: `the Bayer patent`) discloses a `puncture-proof` tire consisting essentially of a single vulcanisable material and comprising a tread thicker than the side walls, a continuous encircling empty space between the base and the tread, with the moment of inertia of the latter being at least six times greater than that of the side walls, and an encircling annular reinforcement of plastics material in the base, hardened after the tire is fitted on the rim of the wheel. This invention suffers from the disadvantages, inter alia, it is not possible to remove the tire from the rim, and this is inconvenient; that the maximum stresses in the tire material that may occur in practice are too high to give a satisfactorily long fatigue life; that its spring constant appears to be too low to cope with sudden very large deflections, i.e. on impact; and that it requires an extra (and, as will be demonstrated below, unnecessary) manufacturing step of introducing a hardenable plastics material. Moreover, we have established that the Bayer patent is using oversimplified criteria for a very complicated problem. The moment of inertia ratio is calculated as follows. Assuming the load carried over a length of tire is b, the two moments of inertia I are given by: I tread =(1/12)b h t 3 and I side wall =(1/12)b h sw 3 , where t stands for tread, sw stands for side wall, and h for height (thickness). Thus, I t /I sw =h t 3 /h sw 3 . For the Bayer patent design h t =11 mm, and h sw =6 mm; then, I.sub.t /I.sub.sw =11.sup.3 /6.sup.3 =6.16. The Bayer patent criterion (I t /I sw >6) would suggest that the maximum stress under load would be similar for the tread region and the side wall region. The Bayer patent's criterion, I(tread)/I(side wall)>6, is related to the concept that the arching type cross-section acts like a bridge in bending, and to have the same bending stress everywhere in the arch requires that the thickness of the arch increase towards the top of the arch where the load is applied. Thus, I t must increase in comparison to I sw . However, this ratio is not a required criteria for tire design. For example, one could let the side wall be 1 mm thick and still require I t /I sw >6, but the tire would collapse under load. We have discovered that it is not necessary to require I t /I sw >6 for a satisfactory design. Using I t /I sw >1 we were able to design the tire so that the maximum stress in the tire did not exceed the fatigue stress limit for long life. For good tire design one must consider all of the physical phenomena involved: 1. contact stress theory, 2. thick walled cylinder theory, 3. rubber stress-strain properties, and 4. fatigue theory. In addition, one must consider a great number of other variables associated with compounding rubber. For example, the amount of wax to introduce into the compound is very important, etc. One method which we have used is the finite element analysis approach to tire design. This method takes into account most of the physical theory involved. Our results show that the Bayer criterion is not a real requirement for good design, and we find that I t /I sw >1 will produce well designed tires. AIMS OF THE INVENTION An aim of the present invention is to provide a tire for vehicles and carts, particularly for wheelchairs and pushchairs, which does not lose its load-bearing capacity even in the event of punctures and/or other minor damage such as small cuts or nicks to the tire, and moreover has very good cushioning properties, as measured by its low spring constant. Another aim of the invention is to provide a tire which will maintain its position on the rim of the wheel under all operating conditions but which is removable, if desired. A further aim of the invention is to provide a tire construction wherein appreciable weight and material can be saved by maintaining at a value the ratio of the moments of inertia of the tread and of the side walls substantially lower than in the prior art, e.g. between 0.75-3.0, and wherein the maximum stresses in the tire material are low for long service life. In addition, yet another aim of the invention is to employ modern mass-production techniques, such as extrusion of the cross-section, curing, cutting to length and joining the ends together to produce a tire of any size appropriate for the rim of the wheel, using dies which are easier and simpler to fabricate. Still another aim of the invention is to provide a tire which can take overloads or side loads without deforming in an unstable fashion. Accordingly, one aspect of the present invention provides a non-pneumatic tire comprising a base for attachment to a vehicle wheel rim, side walls and a tread merging with one another, wherein: (a) the tire includes at least one continuous encircling empty space between the said base and the said tread; (b) the size of the said encircling empty space(s) is selected so as to result in a tire wall thickness providing a spring constant similar to conventional tires; (c) the said tire contains reinforcing means to maintain the position of the tire on the wheel under substantially all operating conditions; and wherein the improvement consists in that. (d) the said tread and side wall are of generally constant thickness along any radius of the tire cross-section. According to another aspect of the invention, there is provided a non-pneumatic tire comprising a base for attachment to a vehicle wheel rim, side walls and a tread merging with one another, wherein: (a) the tire includes at least one continuous encircling empty space between the said base and the said tread; (b) the size of the said encircling empty space(s) is selected so as to result in a tire wall thickness providing a spring constant k in the range of 100-200 N/mm, (c) the said tire contains reinforcing means to maintain the position of the tire on the wheel under substantially all operating conditions; (d) the ratio of the moment of inertia of the said tread to that of the said side walls is substantially 0.75-3.0. By `non-pneumatic` tire is meant a tire that may or may not have at least one air-filled cavity in which the air in said cavity is essentially at atmospheric pressure, i.e. not pressurized; and the tire does not have a valve or other device to allow air under pressure to be introduced into the said cavity. The preferred material for the tire is one which has the ability to undergo large deformations and to recover quickly. Natural and synthetic rubber, and other rubber-like polymers, unfilled or filled with reinforcing materials, are candidate materials for use in the tires according to the invention. The tread of the tires may be smooth or may be provided with profiles. It is preferable that the profiles, such as beads or grooves, be continuous over the periphery of the tire, applied e.g. by an embossing tool, as is well-known in the extrusion art. In the case where the tire is extruded and then moulded it is understood that any process known to the art may be applied for producing treads or embossing tires. Preferably, there are two encircling empty spaces in the tire, the spaces being juxtaposed across the width of the tire such that a rib extending in the direction from the base to the tread is formed therebetween, the dimensions of said spaces being selected such that the height and width of said rib are effective to produce a tire with a low spring constant, preferably below 200 N/mm. In principle, the one or two encircling empty spaces between the base and tread may be of any cross-sectional shape. The preferred shape of the one or two empty space(s) is, however, circular as being the shape that will minimize fatigue failure of the material; it is well-known that sharp corners are sites for stress concentration leading to early fatigue failure. It is desirable to have a spring constant k for the tire that is similar to that of a pneumatic tire, of the order of 100-200 N/mm, most preferably k=130 N/mm, as it has been shown that the low spring constant of a pneumatic tire gives the most comfortable ride: Gordon, J., Kauzlarich, J. J. and Thacker, J. G. `Tests of Two New Polyurethane Foam Wheelchair Tires`, Journal of Rehabilitation R & D, V. 26, No. 1, 1989, pp. 33-46. DESCRIPTION OF THE DRAWINGS Preferred embodiments of tires according to the invention are described below, purely by way of example, with reference to the accompanying drawings, wherein: FIG. 1 is a cross-section through a press-fitted tire according to a first embodiment of the invention; FIG. 2 is a cross-section through a tire according to a second embodiment of the invention in which the base of the tire is joined to the wheel rim; and FIG. 3 is a cross-section through a tire according to another preferred embodiment of the invention. DESCRIPTION OF THE PREFERRED EMBODIMENTS Throughout the description the same reference numbers have been used to designate the same or functionally equivalent parts. Referring first to FIG. 1, a cross-section through a tire 10 for a slow-moving vehicle (wheelchair, cart) that has been press-fitted to the rim of a wheel is shown. The tire 10 has a tread 11 which is essentially of constant cross-section or thickness across the width of the tire 10. It is preferably provided with profiles 12 and is connected by way of side walls 13 to the base 14 of the tire adapted to the contour of the rim 15 of a wheel. The height of the tire 10 from the tread 11 to rim 15 is designated by H. The body of the tire 10 contains two circular encircling cavities or empty spaces 16 which, in this example, are juxtaposed in a widthwise spaced apart, parallel relationship to form a rib 20 therebetween. Their function is to control the spring constant of the tire by establishing the effective width W of the centrally located vertical rib 20 of the tire. The relation between the height H of the tire and the width w of the rib, along with the appropriate modulus of elasticity of the rubber according to equation (1), see below, can be adjusted to optimize the spring constant to a low value, preferably 100-200 N/mm. One or more layers of cord or spiral wire (or other reinforcing means) 17 serve to reinforce the tire so as to prevent disengagement of the tire 10 with the rim 15 under operating conditions. The ratio of the moment of inertia of the tread 11 to that of the side walls 13 is generally in the range of 0.75 to 3.0, most preferably close to unity. FIG. 2 is a cross-section of another preferred tire joined to the rim 15 of a wheel the tire-rim interface 21. In FIG. 2 the cords or spiral wire 17 (or other reinforcing means) are omitted and the base 14 of the tire is joined to an extension 30 of the wheel rim 15 by any suitable method of attaching rubber to metal or plastic; the joining methods may or may not involve vulcanization processes and are well-known to the tire industry, e.g. `Chemlock` bonding agents. Again, the tire includes two encircling empty spaces 16 placed to ensure a comfortable ride by controlling the height (H) to rib width (W) ratio in accordance with equation (1), see below. In this embodiment, H is measured from the tread 11 to the nearest point of the base, namely to the proximate surface of the flange 30. The joint between the tire and wheel rim contains a lip 27 to reduce the joint stress at the rim and tire joint. In the preferred embodiments of the invention shown in FIGS. 1 and 2, the spring constant k for the tire is found to obey approximately the following simple equation derived from the theory of strength of materials: k=E×A/H=k.sub.o ×E×W/H (1) where E is modulus of elasticity of the material, preferably rubber, A is the effective loaded cross-sectional area of the vertical rib 20, H and W are as before, and k o is a coefficient depending upon the particular embodiment of the invention. In the case of FIG. 1 the value of k o is found to be of the order of 75 mm, and for FIG. 2 k o is of the order of 70 mm. Thus, using equation (1) it is possible to predict the effect on the spring constant (k) of changing the modulus of elasticity, E, of the rubber, for example. The properties of the rubber have been selected so that the design variables are optimized as to spring constant as well as other desirable tire characteristics. FIG. 3 is a cross-section of another preferred tire including a single, central encircling empty space (16) effective to control the side wall thickness so that the spring constant of the tire will be low and the tire gives a cushioned ride. One or more layers of cord 17, spiral wire or other reinforcing means serve to reinforce the tire. Whilst for high vertical and side loads the embodiments of the invention using two encircling empty spaces and shown in FIG. 1 and FIG. 2 are preferred, the embodiment of the invention according to FIG. 3 is primarily applicable to wheelchairs and pushchairs where the vertical and side loads are less severe. The side wall thickness must not be too thin so as to cause high stresses in the material or collapse under loads. As in the previous preferred embodiments of the invention, so also in the FIG. 3 embodiment with its single encircling empty space 16, finite element analysis of the complicated Hertz stresses and consideration of thick-walled shell stresses are required to design the wall thickness of the tire so that the beneficial low spring constant is achieved while maintaining sufficiently low stresses due to loads so as to avoid early fatigue failure of the material. Where large side loads are encountered the tire design with two encircling empty spaces 16 is required for stability of the structure, see Kauzlarich, J. J.: "FEA of Solid Rubber Wheelchair Tires", Proc. of Contact Analysis Meeting, Inst. of Physics Short Meeting Series No. 25, London 1990, pages 15-22. As shown in FIG. 3, the tread and side wall are of constant thickness along any radius (i.e., from center of empty space 16) of the tire cross-section. With the embodiments having two encircling empty spaces 16, i.e. FIG. 1 and FIG. 2, the side walls 13 act to support the central vertical encircling rib 20 of the tire. The action of the side walls 13 is somewhat analogous to that of the flying buttresses of a classical European cathedral, in that the side walls 13 are abutments for the central rib 20 of the tire and are thus especially effective in stabilizing the tire against overloads and side forces. The base 14 of the tire itself is adapted in its shape to the contour of the rim of the wheel. When the base 14 of the tire is not joined to the wheel rim the base of the tire contains cords or spiral wire 17 (or other reinforcing means) joined to the material of the tire, and the cords or spiral wire 17 as reinforcement to prevent the tire from detaching from the rim under operating conditions. Alternatively, the cords or spiral wire 17 could be located in the encircling empty spaces 16 of the tire and the cords or spiral wire would be tied before joining the ends of the extrusion to form a tire. In principle, any cord, spiral wire or other reinforcing means that makes a bond with the rubber may be used as reinforcement in the base of the tires which are designed to be press-fit to the rim of the wheel (cf. FIG. 1 and FIG. 3). For cord, spiral wire or other reinforcing means inserted in the encircling empty spaces and tied with a knot it is not necessary that the cord, wire or other reinforcing means are bonded to the rubber. The production of tires according to the invention is simplified by comparison with conventional pneumatic tires because such tires are particularly amenable to production by extrusion and vulcanization of the properly shaped cross-section of the tire, including (for the FIG. 1 and FIG. 3 embodiments) cord, spiral wire or other reinforcing means, and tread patterns. Accordingly, the economic saving with respect to producing pneumatic tires is considerable. DESCRIPTION OF MATERIALS The tires according to the invention may be made of any natural or synthetic rubber having the following desirable characteristics. The material is selected to: (a) minimize the wear; (b) minimize compression set; (c) minimize hysteresis losses; (d) maximize fatigue strength; (e) give satisfactory extrusion and moulding characteristics; (f) make no tire marks to a floor (where required), and (g) minimize cost. Optimizing all of the above factors has been accomplished by using the following rubber mixture: Polymer Natural rubber (NR) synthetic rubbers such as polyisoprene, styrene-butadiene rubber or polybutadiene or Superior Processing (SP) rubbers or blends of those polymers. SP rubbers are a special type of natural rubber made from mixtures of pre-vulcanized latex and normal latex which are subsequently processed similarly to conventional NR. Typical market grades include SP20, SP40, SP50, PA80. The numeral indicates the percentage of pre-vulcanized latex. SP rubbers may be blended with other grades of NR or synthetic rubber. Improvements in extrusion characteristics are observed when SP rubbers are incorporated in the mix. Suggested composition ranges: ______________________________________Polymer as defined above 100Non-black filler.sup.1 30-60Rubber-filler coupling agent.sup.2 0-6Process aid.sup.3 0-5Zinc oxide 1-10Stearic acid 0-5Antioxidant, non-staining.sup.4 0-3Wax 0-10Biocide.sup.5 0-3Antistatic agent.sup.6 0-20Whitening agent 0-20Accelerator.sup.8 0.3-4.0Sulphur 0-4Silica activator.sup.9 0-3______________________________________ .sup.1 e.g. precipitated silica .sup.2 e.g. Triethyoxysilylpropyl tetrasulphide, such as SI69 (Degussa) .sup.3 e.g. Struktol WB16 (Schill & Seilacher) .sup.4 e.g. Wingstay L (Goodyear) .sup.5 e.g. Preventol G (Bayer) .sup.6 e.g. Antistaticum (Rhein Chemie), aluminium flake or sodium aluminium silicate .sup.7 e.g. Titanium dioxide .sup.8 e.g. Vulkacit J (Bayer) .sup.9 e.g. Diethylene glycol or triethanolamine The materials suitable for tires according to the invention will now be further described with the aid of three non-limiting Examples. ______________________________________ Ex- Ex- Ex- ample 1 ample 2 ample 3______________________________________Preferred compositionsNR 100 50 100SP40 (SP rubber) -- 50 --Ultrasil VN3 Silica (filler) 40 40 40SI69 (rubber-filler coupling 5 4 3agent)Struktol WB16 (process aid) 4 4 4Zinc Oxide 5 5 5Stearic Acid 2 2 2Wingstay L (antioxidant) 1 1 --Antioxidant 2246 -- -- 1Preventol G (biocide) 1 1 1Wax 5 5 5Titanium dioxide (whitener) 1 1 --Vulkacit J (accelerator) 3.4 2.7 --Sulphur -- -- 3.5N-cyclohexylbenzothiazole-2- -- -- 1.0sulphenamide (cross-linkingaccelerator)Diethylene glycol (silica -- -- 1.5activator)Physical PropertiesCure time min/150° C. 60 60 35Density 1.11 1.12 1.11Hardness, IRHD 65 66 66DIN abrasion, mm.sup.3 145 180 230M100, MPa 2.7 2.3 2.6M300, MPa 12.2 11.0 8.1TS, MPa 25.5 26 26EB, % 480 525 620Compression set, %3 days at 23° C. 12 12 131 day at 70° C. 15 18 28Trouser tear (ISO34), N/mm 10 13 23Ring fatigue life, Kilocycles 57 54 49to failure 0-100% extensionTension hysteresis, % 10 15 11______________________________________ M100 and M300 stand respectively for the modulus of elasticity at 100% an 300% extension, TS stands for tensile strength, and EB for extension to break point. The following Table illustrates the improved performance characteristics of a wheelchair tire made according to the invention: ______________________________________Performance Characteristics Comparisona.Tire according to theinvention, 60 cm dia. b. Pneumatic Tire, 60 cm dia.______________________________________1. MAINTENANCEa. Maintenance-free b. 4.35 kg/cm.sup.2 or 60 psig inflation pressure2. WEIGHTa. 880 grams (1.94 lbs) b. 734 grams (1.62 lbs)(tire & tube)3. SKID MARKINGa. Non-marking b. Non-marking4. ROLLING RESISTANCEper tire (of 7.5% hysteresis rubber), 27.25 kg (60 lbs) load,2.4-4.8 kph (1.5-3 mph)a. 265 grams (0.59 lb) b. 263 grams (0.58 lbs)5. COEFF. OF FRICTION (CONCRETE FLOOR)a. 0.85 (dry or wet) b. 0.656. TIRE SPRING CONSTANT [0-27.25 KG (0-60 LBS) LOAD](low spring constant indicates good ride quality)a. 130 kg/cm or 730 lbs/inch b. 124 kg/cm or 694 lbs/inch7. ROLL-OFF (12 deg. max)a. No b. No8. ABRASIVE INDEX (WEAR RATE)Higher values = lower wear rate.a. 110 b. 199. COMPRESSION SET (23° C.)a. 13% b. 10.6%10. LIFEa. Exceeds life of wheelchair b. 3 years (average puncture period)______________________________________ Note: the rolling resistance will vary in proportion to the hysteresis of the rubber. TIRE TESTING The current design of testing machine proposed as an international standard device consists of two rotating drums, one under the rear wheels and one under the front wheels. The drums have bump slats 10 mm high impacting the tires, and the drums are rotated about an off axis axle to twist the wheelchair frame. Initial work with this machine by the applicants on non-pneumatic tires showed that the foamed polyurethane tires failed by crack propagation and chunking and cutting at an early life. It is believed that the very low fatigue endurance limit for foamed elastomers contributes mainly to this problem. Tires according to the invention overcome the above problem by its very high fatigue endurance limit. In comparison to all other white rubber tire materials preferred compounds according to the invention show (1) less heat build-up, (2) higher endurance in service, (3) better tear, chipping, chunking and cutting properties, especially at elevated temperatures, and (4) higher modulus retention at elevated temperatures. RUBBER COMPOUNDING The preferred compounds use SI-69, a silane coupling agent that is a reinforcing agent for siliceous fillers developed by DEGUSSA, see Wolff, S., `Theoretical & Practical Aspects of SI 69 Application in Tires`, DEGUSSA AG, Paper 2148. This new agent solves the following problems usually associated with silica fillers: (a) Small additions of SI-69 reduces the compound viscosity to the same or lower level as compounds using carbon black; (b) The cure characteristics of SI-69 based compounds avoid reduction in cure rate and cross-linking density; and (c) at the same surface area as carbon blacks SI-69 promotes the erection of filler-to-rubber bonds which causes a strong increase in the in-rubber surface area of the silica filler comparable to values close to the in-rubber surface of N-220 carbon black.

4y

The development of the technology described herein was supported by NSF Grant No. EEC-96-15774 for the study of high-speed, high-resolution micro-optical scanners. The U.S. Government may have certain rights in this technology. BRIEF DESCRIPTION OF THE INVENTION This invention relates generally to optical scanners and displays. More particularly, this invention relates to an optical raster-scanning microelectromechanical system. BACKGROUND OF THE INVENTION Scanning micromirrors fabricated using surface-micromachining technology are known in the art. As used herein, a micromirror, a microscopic device, a micromachined device, a micromechanical device, or a microelectromechanical device refers to a device with a third dimension above a horizontal substrate that is less than approximately several milli-meters. Such devices are constructed using semiconductor processing techniques. Scanning micromirrors have numerous advantages over traditional scanning mirrors. For example, they have smaller size, mass, and power consumption, and can be more readily integrated with actuators, electronics, light sources, lenses and other optical elements. More complete integration simplifies packaging, reducing the manufacturing cost. These factors add motivation to the development of microfabricated scanners. In addition to displays, high-speed, high-resolution micro-optical scanners have numerous additional applications in medicine, lithography, printing, data storage and data retrieval. U.S. Pat. No. 5,867,297 (the '297 patent) entitled “Apparatus and Method for Optical Scanning with an Oscillatory Microelectromechanical System” describes early seminal work in the field of oscillatory micromirrors. The contents of the '297 patent are expressly incorporated by reference herein. The required system tolerances in a system of the type described in the '297 patent are extremely high. For example, bending of torsional hinges causes system wobble, defined as rotation about an axis in the mirror plane orthogonal to the primary scan axis. In a two mirror system including a fast mirror and a slow mirror fast mirror wobble of less than 1% of the total deflection angle will cause scan lines to overlap and seriously degrade image quality. In the slow mirror, rotational errors known as jitter, attributable to errors in following the driving signal, can induce non-uniform line spacing. It would be highly desirable to establish improved mechanical linkages to enhance mirror performance. Large mirror diameters and rotational angles, facilitated by a tilt-up mirror design, are key to the resolution of a scanning system. Moving a large mirror quickly through a large angle requires high-force actuators and stiff springs to achieve a high resonant frequency. Mechanically, the image resolution is limited by the number of lines that the fast mirror can scan during the refresh period of the slow mirror. Optically, the resolution is given by the size, flatness and rotational angle of the mirror. Increasing the mirror diameter results in higher resolution only if the mirror is flat, or if its curvature is optically corrected. It would be highly desirable to provide a method of characterizing and correcting static mirror curvature to improve the performance of an optical raster-scanning system. SUMMARY OF THE INVENTION A method of operating a micromechanical scanning apparatus includes the steps of identifying a radius of curvature value for a micromechanical mirror and modifying a laser beam to compensate for the radius of curvature value. The identifying step includes the step of measuring the far-field optical beam radius of a laser beam reflected from the micromechanical mirror. The measured far-field optical beam radius is then divided by a theoretical far-field optical beam radius reflected from an ideal mirror to yield a ratio value M. An analytical expression for M is curve-fitted to experimental data for M with the focal-length as a fitting parameter. The focal-length value determined by this procedure, resulting in a good fit between the analytical curve and the experimental data, is equal to half the radius of curvature of the micromechanical mirror. The micromechanical scanning apparatus is operated by controlling the oscillatory motion of a first micromechanical mirror with a first micromechanical spring and regulating the oscillatory motion of a second micromechanical mirror with a second micromechanical spring. The invention provides an improved optical raster-scanning micromechanical system. Mirror performance in the system is improved through the technique of characterizing and correcting static mirror curvature. Improved mechanical linkages that exploit symmetry reduce mirror wobble. A triangular control signal maximizes the linearity of the scan. BRIEF DESCRIPTION OF THE DRAWINGS For a better understanding of the invention, reference should be made to the following detailed description taken in conjunction with the accompanying drawings, in which: FIG. 1 illustrates an optical raster-scanning apparatus in accordance with an embodiment of the invention. FIG. 2 illustrates an optical raster-scanning apparatus in accordance with another embodiment of the invention. FIG. 3 illustrates an optical raster-scanning apparatus in accordance with still another embodiment of the invention. FIG. 4 is a perspective view of a fast mirror for use in accordance with an embodiment of the invention. FIG. 5 is a top view of a spring utilized in accordance with an embodiment of the invention. FIG. 6 is a side view of the spring of FIG. 5 . FIG. 7 is a perspective view of a slow mirror for use in accordance with an embodiment of the invention. FIG. 8 is an enlarged perspective view of a portion of the slow mirror of FIG. 7 . FIG. 9 illustrates the frequency response of a fast mirror constructed in accordance with an embodiment of the invention. FIG. 10 illustrates the frequency response of a slow mirror constructed in accordance with an embodiment of the invention. FIG. 11 illustrates far-field optical effects of a curved mirror; this information is used in accordance with the invention to compensate for mirror curvature. FIG. 12 illustrates the aperture effect of a mirror in the far-field. FIG. 13 illustrates the effect of mirror deformation due to comb drive actuation. Like reference numerals refer to corresponding parts throughout the drawings. DETAILED DESCRIPTION OF THE INVENTION FIG. 1 is a simplified representation of an optical raster scanning system 20 constructed in accordance with an embodiment of the invention. The system 20 processes a laser beam 22 with a first mirror 30 , implemented as a micromechanical device. The first mirror 30 may be a “fast mirror”, as described below, which pivots about a first axis of rotation 26 , causing first rotational motion, as shown with arrow 28 . As described below, the first rotational motion is achieved by pushing or pulling the bottom edge of the mirror 30 . FIG. 1 also illustrates a second mirror 24 , which is also implemented as a micromechanical device. The second mirror 24 may be a “slow mirror”, as described below, which pivots about a second axis of rotation 32 , causing second rotational motion, as shown with arrow 34 . As described below, the second rotational motion is achieved by pushing or pulling the left and right sides of the mirror 24 . By controlling the motion of the slow mirror 24 and the fast mirror 30 , the laser beam 22 is projected onto a screen 36 to establish a predetermined pattern, as will be discussed further below. FIG. 2 is a more detailed depiction of an optical raster scanning system 20 in accordance with an embodiment of the invention. The system 20 of FIG. 2 has its mirrors 24 and 30 fabricated on a single semiconductor substrate 38 . A laser 40 generates a laser beam 22 , which passes through an acousto-optic modulator 42 . The laser beam 22 is subsequently directed through a spatial filter 44 and through a mechanical shutter 46 . Thereafter, in accordance with a feature of the invention, the laser beam 22 is processed by mirror curvature compensation optics 48 . The optic assembly 48 operates to compensate for mirror curvature features that would otherwise degrade optical performance, as discussed in detail below. The laser beam 22 is then controlled by the first mirror 30 and the second mirror 24 , with the laser beam 22 output being directed by an output mirror 50 . Output optics 52 may process the laser beam 22 before it is applied to a camera 54 or screen. The system of FIG. 3 corresponds to the system of FIG. 2 with two exceptions. First, in the system of FIG. 3, the mirrors 24 and 30 are not formed on a single substrate, instead they are individually fabricated. Second, imaging optics 60 are used between the first mirror 30 and the second mirror 24 . The micro-mirrors 24 and 30 are synchronized with a modulated light source. Modulation of the light source is used to display information with the raster-scanner. Switching the light on-and-off defines the pixels in the display. Grey-scale images can be generated with the use of analog or digital modulation of the light source. Laser diodes and light-emitting diodes are suitable for this application. Instead of a projection device 54 , light from the micro-mirror display system can be projected directly on to the retina of the user. Projection on to the retina eliminates the need for a display screen in a head-mounted display. Such an embodiment reduces the weight and cost of the system. FIG. 4 illustrates a fast mirror 30 constructed in accordance with an embodiment of the invention. The mirror 30 is positioned within a mirror frame 62 . Torsional bars 64 A, 64 B connect the mirror 30 to the mirror frame 62 . The torsional bars 64 operate in the manner described in the previously referenced '297 patent. FIG. 4 further illustrates a mirror frame lift 66 and a mirror lifter 68 . These devices may be fabricated and otherwise operate in accordance with prior art techniques. The mirror 30 of FIG. 4 has an associated comb drive 70 , which is controlled by electrodes 71 A, 71 B, and 71 C. A comb drive central beam 72 is driven by the comb drive 70 in a controlled manner. The motion from the comb drive central beam 72 is transferred to a mirror slider 73 , which pushes or pulls the mirror 30 . More particularly, it pushes or pulls the bottom of the mirror 30 to rotate the reflected laser beam. The features discussed in connection with FIG. 4 are consistent with those described in the '297 patent, with the following exception. In accordance with the invention, the comb drive central beam 72 is attached to micromechanical springs 74 A and 74 B. The springs 74 operate to improve the controlled motion of the mirror 30 . In the embodiment of FIG. 4, the springs 74 are axially aligned with the comb drive central beam 72 . This configuration has been particularly successful in enhancing the range of motion for the fast mirror 30 . FIG. 5 is a top view of a spring 74 utilized in accordance with an embodiment of the invention. The spring 74 is attached to the comb drive central beam 72 . The spring 74 includes two interior beams 82 A and 82 B, two exterior beams 82 C, and 82 D, and connecting bars 80 A and 80 B. Beams 82 A and 82 B are attached to an anchor 84 . FIG. 6 is a side view of the spring 74 taken along the line 6 — 6 of FIG. 5 . As shown in FIG. 6, the anchor 84 operates to suspend the spring 74 over its substrate 86 . In particular, FIG. 6 illustrates that beam 82 B is attached to the anchor 84 , holding the beam 82 B and the remaining portion of the spring above the substrate 86 . Back and forth motion, as illustrated by arrow 90 in FIG. 5, imparted by the comb drive central beam 72 from the comb drive 70 causes the beams 82 to flex in a controlled manner to improve the resultant motion imparted to the mirror 30 . FIG. 7 illustrates a slow mirror 24 positioned on a substrate 90 . The slow mirror 24 has torsion bars 92 A and 92 B respectively positioned at the top and bottom of the mirror 24 . A mirror frame 94 supports the mirror 24 , via the torsion bars 92 A and 92 B. A mirror frame lift 96 and mirror lifter 98 position the mirror 24 over the substrate 90 . FIG. 7 also illustrates individual comb drives 100 A and 100 B. Each comb drive 100 A and 100 B respectively controls an individual comb drive central beam 102 A and 102 B. Each comb drive central beam 102 A/ 102 B is attached to a mirror slider. Each mirror slider comprises a first transverse member (e.g., 105 A), which is transverse to its linked comb drive central beam (e.g., 102 A), an aligned member (e.g., 108 ), which is aligned or parallel with its associated comb drive central beam (e.g., 102 A), and a second transverse member (e.g., 110 A). The second transverse members 110 A and 110 B are respectively connected to mirror flanges 112 A and 112 B. The motion of the slow mirror 24 is controlled by springs 114 A and 114 B, of the type described in connection with FIGS. 4-6. FIG. 7 illustrates that the spring 114 A has deflected beams (e.g., 116 ). The orientation of the deflected beams indicates that the mirror 24 is being pulled at flange 112 A (left side of the mirror out of the page) and pushed at flange 112 B (right side of the mirror into the page). As in the case of the fast mirror 30 , the motion of the slow mirror 24 is controlled by springs. That is, the springs 114 improve the motion of the mirror slider components 108 , 105 , and 110 , which improves the motion imparted to the mirror flanges 112 . The configuration of FIG. 7 has symmetric actuation imparted by the comb drives 100 to produce improved mirror motion. FIG. 8 is an enlarged view of the bottom portion of the slow mirror 24 . The figure illustrates the torsion bar 92 B. The torsion bar 92 B may be connected to a conventional pin and staple hinge 130 . FIG. 8 also illustrates the mirror flange 112 A, which includes a box frame 122 at its terminal end. The second transverse member 110 of the mirror slider includes a T-shaped termination member 124 , which is positioned over the bottom link of the box frame 122 . The T-shaped termination member 124 insures that the second transverse member 110 and the mirror flange 112 stay assembled. A similar linkage mechanism is used between the fast mirror 30 and its slider 73 . Note that the mirror slider components 105 , 108 , and 110 are suspended over the substrate 90 , allowing controlled motion. FIG. 8 also illustrates a portion of each individual comb drive 100 A and 100 B. Comb drive segment 131 of comb drive 100 B is electrically connected to comb drive segment 132 of comb drive 100 A. Similarly, comb drive segment 134 of comb drive 100 B is electrically connected to comb drive segment 133 of comb drive 100 A. If a voltage is applied to comb drive segments 133 and 134 , the mirror slider pushes the mirror flange 112 A into the plane of the page, while the opposite mirror slider pulls the opposite mirror flange out of the plane of the page, resulting in a clock-wise motion. The physical components of the apparatus of the invention have now been described. Attention presently turns to a more detailed discussed of attributes associated with various physical implementations of the device. A detailed discussion of the operation of the device will also follow. In particular, the following description will address improvements in the control signals used in connection with the apparatus and techniques to improve the optical output of the apparatus by compensating for mirror shape anomalies. Standard MEM processing techniques may be used to fabricate the mirrors and springs of the invention. In one embodiment of the invention, two free-standing polysilicon layers are used to create the mirrors ( 24 , 30 ), comb-drives ( 70 , 100 ) and tilt-up frames ( 66 , 96 ). The devices may be fabricated with the Multi-User Microelectromechanical Systems Processes (MUMPs) described by K. W. Markus, et al., in “MEMS Infrastructure: The Multi-User MEMS Processes (MUMPs)”, Proc. SPIE , Vol. 2639 (Micromachining and Microfabrication Process Technology, Austin, Tex. USA, 23-24, Oct. 5, 1995), p. 54-63. Similarly, the processing techniques described in the previously referenced '297 patent may be utilized. After fabrication, the devices may be released in a 49% Hydroflouric (HF) acid solution and dried in a supercritical Carbon Dioxide (CO 2 ) chamber. After release and drying, the chips may be covered with 50 nm of aluminum by blanket evaporation to enhance mirror reflectivity. Overhanging polysilicon structures are preferably used to avoid electrical shorts caused by metal deposition. This design feature was tested successfully on the single-chip scanner. The mirrors ( 24 , 30 ) and torsion beams ( 64 , 92 ) have been implemented with 1.5 μm-thick polysilicon. The tilt-up frames, comb-drives and folded springs have been implemented with 3.5 μm-thick polysilicon. The tilt-up frames are used to raise the mirrors out-of-plane and hold them securely. The frames are connected to the mirrors by torsional hinges and to the chip surface by pin-and-staple hinges, as illustrated in FIGS. 4 and 7. The frames and mirrors may have 3 μm-diameter etch holes spaced on a 30 μm grid for fast release in HF. Each mirror, originally fabricated flat on the chip surface, may be assembled using a probe on a micropositioner. The probe is used to push forward the lifters 68 , 98 which are connected to the back of the frames 62 , 94 . The mechanical stability of the scanning mirrors can be improved by fixing the frame joints with epoxy. As previously discussed, the mirrors are actuated by comb-drives that are connected to the mirrors through hinges near the chip surface. The comb-drives move in the plane of the chip. The folded springs ( 74 , 114 ) provide the majority of the stiffness for the actuator-mirror system. All comb-drives used to actuate the mirrors can be operated bi-directionally, i.e. two sets of comb teeth are used, one set pulling in the opposite direction of the other. At resonance, a mirror need only be driven in one direction, and the inertia of the system will cause it to oscillate nearly symmetrically about its equilibrium point. If a mirror is operated below its resonant frequency, it is must be driven bi-directionally to achieve maximum deflection. As previously illustrated, the fast mirror 30 rotates about an axis parallel to the chip surface, and the slow mirror 24 rotates about an axis perpendicular to the surface. The fast mirror 30 may be implemented with a 65-by-500 μm rectangle flanked by two 500 μm-diameter half-circles, making the mirror nearly circular. In one embodiment, it rotates about its long (565 μm) axis, and has a resonant frequency of 4.68 KHz (FIG. 4 ). Fast-mirror frequency-response curves were collected from devices on several chips. Each mirror had a slightly different resonant frequency, ranging from 4.54 KHz to 4.68 KHz. All fast mirrors were driven at 4.6 KHz when used to generate the horizontal component of a raster-scan. The device characterized in FIG. 9 is from a single-chip display. The fast-mirror torsional hinges 64 may be 50 μm×3 μm×1.5 μm, and the folded spring 74 may be 299 μm×3 μm×3.5 μm, supporting opposing banks of 66 comb teeth, each 40 μm×3 μm×3.5 μm. The measured optical scan angle of the fast mirror is 15 degrees when operated at resonance, driven with a 36.1 V rms sine wave and zero DC offset. The slow mirror 24 may have the same shape as the fast mirror but may be elongated along its axis of rotation by the insertion of a 253-by-565 μm rectangle to collect the light from the fast-mirror scan. The slow mirror 24 may be actuated symmetrically by two banks of comb-drives ( 100 A, 100 B), each driven with a triangular voltage waveform at 60 V pp and zero DC offset. Driving the opposing comb-drives at 90 degrees out-of-phase results in a net triangular-force waveform. Using a triangular-shaped waveform instead of a sinusoidal driving signal increases the linear region of the slow-mirror scan. The comb drives 100 A, 100 B for the frame-refresh (slow) mirror 24 of FIG. 7 are used to produce a push-pull force on the frame-refresh mirror 24 . The frame-refresh mirror 24 must be driven in both directions because it is operating below its resonant frequency. It is advantageous for the mirror angle versus time to follow a triangular waveform centered about zero. By making a fast reversal of the scan direction at each edge of the frame scan (at the peak or valley of a triangular waveform), and holding a constant velocity over the majority of the frame, fast-scan lines can be easily projected with uniform spacing. Correction for non-linear velocity changes are not necessary. The opposing comb drives 100 A, 100 B allow the use of piecewise linear, symmetric triangle waves to achieve a triangular force waveform for mirror actuation. If just one comb drive were used, the net electrostatic force would be proportional to the square of the applied voltage. If a triangular waveform were applied to a single comb drive, the resulting force would not be piecewise linear. A triangular voltage waveform applied to a mirror with the opposing comb drive design yields a net electrostatic force that is proportional to the input voltage (and phase-shifted). The optical modulation for the display need not be modified to correct for non-linear motion of the mirror. The slow-mirror folded springs 114 may be 600 μm×3 μm×3.5 μm. The comb tooth design is the same as that found on the fast mirror, except 132 teeth are available to drive the mirror in each direction. The slow mirror deflects the optical beam through 15 degrees on an axis orthogonal to the fast mirror and has a resonant frequency of 1.14 KHz, as illustrated in FIG. 10 . The slow mirror 24 moves at a sub-harmonic frequency of the fast mirror 30 . This simplifies the driving electronics for the optical modulator. There are an integer number of line-scan cycles in the image refresh mirror cycle. The resolution of a raster-display is determined by both mechanical-system issues and the optical quality of the mirror surfaces. The resonant frequency of the fast mirror limits the display resolution by restricting the number of lines that can be canned during the image refresh period. In visual display systems, ergonomics must be considered when determining the image refresh rate. Factors that affect flicker perception include the location of the image in the visual field, the average luminance of the display, and direction of the raster scan. A high-quality scanning display should require an image refresh rate of about 100 Hz. Raster-scan images described herein make use of the left-to-right and top-to-bottom portions of the fast and slow mirror scans, respectively. Using the other half-cycle of the fast and slow-mirror scans boosts the mechanically-limited resolution by a factor of four. The optical resolution is a function of the maximum optical scan angle divided by the angular divergence of the reflected laser beam, as described below. Curvature of the mirror surface increases the divergence angle of the reflected beam. Mirror curvature caused by actuation forces or stress gradients inherent in the fabrication process will therefore severely degrade the scan resolution if left uncorrected. The laser 40 of FIGS. 2 and 3 may be a 5 μW, 633 μm Helium-Neon (HeNe) laser source. Unlike spatially incoherent sources, nearly all of a laser's optical power can be focused onto the surface of a micro-scanning mirror, and eventually to the display screen 36 (FIG. 1 ). This simplifies the transfer of high-optical power density through micro-optical systems. In addition, optical analysis is simplified by the narrow spectral and uniform phase characteristics of the laser. The following discussion assumes that the light source is monochromatic and spatially coherent with a transverse Gaussian distribution. Within the Gaussian beam propagation model, the best resolution for an optical scanner is obtained by positioning the waist of the incident optical beam at the surface of the micromirror and the image plane in the far-field. A number of different geometries will achieve the same resolution as this configuration, but none are likely to improve performance. The standard rule of thumb for analog (scanning) cathode ray tube designs is that neighboring pixels should be separated by the Full Width at Half Maximum (FWHM) of their intensity. Given this criterion, the number of resolvable spots for a one-dimensional scanner is given by: N = απω m 1.178  λ ( Equation     I ) where α is the optical scan angle, ω m is the radius of the optical beam waist on the mirror (in this discussion, optical beam radius always refers to the radius of the laser beam at its 1/e 2 intensity value), and λ is the optical wavelength. To improve the resolution, it is necessary to increase the product αω m . Mirrors that accept a large optical beam and rotate through large angles are desired. Equation I represents an ideal scanning mirror that is perfectly flat and of infinite extent. Curvature and imperfections of the optical surface, as well as the finite size of a real mirror, will reduce the resolution. Stress-gradient-induced mirror curvature is dominant among these. In the disclosed two-mirror display system, mirror curvature will typically cause an increase in the area of the far-field optical beam by a factor of more than 1000 if left uncorrected. By approximating the curved-mirror profile as parabolic, one can calculate the increase in the far-field beam size and the proportional reduction in resolution. This may be expressed as the ratio M of the actual optical beam radius to the theoretical beam radius for an ideal, flat mirror of infinite extent M = 1 | f | λ  ( fλ ) 2 · ( πω m 2 ) 2 ( Equation     II ) where ƒ is the focal length of the mirror and ω m is the radius of the incident optical beam waist on the mirror. To optically compensate for the curvature of a micromirror, its radius of curvature, or equivalently, the focal length of the mirror, must be found. To do this, the far-field optical beam radius is measured for several laser beam waist sizes on the mirror. Dividing the measured far-field optical beam radius by the theoretical far-field optical beam radius of a perfectly flat, infinitely large mirror yields the value of M. Typical examples of experimentally determined values of M for scanners of the invention are plotted in FIG. 11 . Equation II is fitted to these points with ƒ as a fitting parameter. Equation II is, strictly speaking, only valid for a mirror of infinite extent, but may be used to fit data for the following reasons. First, for small incident beam-waist-radii less than three times the mirror radius, there is effectively no diffraction off the mirror edges. Second, larger incident optical beams are greatly expanded by the mirror curvature in the far-field, causing the relative influence of the aperture effect to be small. Testing with polysilicon mirrors indicates that resolution loss due to curvature is small for an incident beam waist less than 50 μm. Equation I, however, shows that larger beam radii, and thus larger mirror sizes, are desired to increase resolution. Increasing the radius of the laser beam on the mirror causes an increased sensitivity to mirror curvature. The mirror characterized in FIG. 11 has an edge-to-center bow of approximately 1.2 μum, which is enough to cause an increase in the far-field optical beam area by a factor of 506 when the mirror is filled with a 250 μm-radius waist. Stress gradients in the polysilicon, inherent to the fabrication process, are the suspected cause of curvature in the mirror. While it may be difficult to flatten the mirror by entirely eliminating stress gradients from the polysilicon, an optical correction is achieved in accordance with the invention. Once the focal length is known, the mirror curvature can be optically canceled by appropriately forming the phase front of the incident optical beam. Using the Gaussian beam propagation model, a two or three-lens system can be designed to pre-form the laser beam such that the waist of the reflected beam is at the surface of the second mirror in a two-mirror system. Orthogonal axes on each mirror can be independently optimized with cylindrical optics. Curvature is the dominant factor in reducing resolution. By correcting for curvature in a two-mirror system, the radius of the optical beam in the image plane is reduced by a factor typically between 30 and 40. This brings the measured far-field optical beam size to within 12% of its diffraction limit (including the aperture effect, see below) simultaneously on both axes of a single-chip scanner. Once the mirror curvature is optically compensated in accordance with the invention, the aperture effect of the mirror becomes significant in determining the diffraction-limited far-field optical beam size. Truncation of the Gaussian laser beam at the mirror broadens the far-field intensity distribution and causes side lobes to appear about the central intensity maximum, as illustrated in FIG. 12 . The relative power in the central and side-lobes is dependent upon the ratio of the incident optical beam radius to the mirror radius. As stated above, if the radius of the mirror is at least three times the radius of the optical beam, the aperture effect of the mirror becomes negligible. Increasing the radius of the incident optical beam reduces the central lobe width of the diffraction patterns. A larger incident beam radius also increases the power in the side-lobes, which is undesirable for display applications. In addition, reflection off of the tilt-up frame surrounding the mirror increases with incident optical beam size, causing artifacts in the raster-scanned image. Taking these factors into consideration, a 250 μm-incident beam radius may be chosen, roughly equivalent to the fast mirror size. For this case, minimal reflection off of the frame is observed, and the power in the side lobes is low. The central lobe, however, expands by about 49% compared to an un-apertured beam, as demonstrated in FIG. 12, and this expansion leads to a proportional reduction of the number of resolvable spots compared to the infinite-mirror case (equation I). Actuation forces on the mirrors will also influence the resolution. The actuators disclosed herein are connected directly to the bottom edges of the mirrors through hinges. The comb-drives induce a torque about the mirrors' torsional hinges, with the mirror surface acting as the moment arm. The applied force at the edge of the mirror causes bending of the optical surface that varies with the rotational position of the mirror. FIG. 13 documents the effect of mirror bending on the far-field optical beam size. The optical beam size at zero deflection is 400 μm, close to the 361 μm-predicted diffraction-limit for a 250 μm beam on a 250 μm mirror and a 30 cm-focal-length output lens. Through the entire range of actuation shown in FIG. 13, the difference between the optical beam radii on perpendicular axes in the far-field remained less than 15%, indicating bending along both axes of the mirror surface. Connecting the comb-drives to an independent lever arm that is attached to the mirror near the torsional hinges will remedy the problem of curvature induced by static actuation forces. Inertial and dynamic forces can also play a role in bending the mirror surface. Preliminary data suggest that dynamic curvature of the fast mirror has a measurable influence on the far-field beam size when the scanner is operated at resonance. The preceding mechanical and optical analyses were used in the design and testing of individual micromachined scanners. The two-mirror raster-scanner design relies on information collected from individual mirrors. The following discussion focuses on the results from single-chip and dual-chip raster scanners. In the single-chip design, the fast and slow mirrors are positioned opposite each other, separated by an optical path length of 936 μm. One method of optical correction for the mirror curvatures requires that the incident optical beam form a virtual waist behind the fast mirror. The fast mirror is tilted back approximately 3 degrees from the perpendicular, allowing the converging incident laser beam to reach the mirror without grazing the chip surface. The slow mirror is normal to the chip surface. The stationary output mirror accepts light from the slow mirror and re-directs it through the output optics to the display screen or camera. A 5.02 cm-focal-length lens, followed by a cylindrical concave lens with focal length -833.3 cm and a 10 cm-focal-length lens correct for the combined curvature of the two-mirror system. The output mirror, made of single-crystal silicon, has negligible curvature. The optical surface of the output mirror must be within approximately 50 μm of the chip surface to capture the full raster scan, and the top of the mirror must tilt away from the slow mirror to direct the light off-chip. To produce a sharp edge at the base of the mirror, the silicon was etched in a KOH bath along a crystalline plane at 54.7 degrees with respect to the polished mirror surface. A micropositioner orients and holds the output mirror in place. The output optics consist of a 10 cm-focal-length lens and additional optics used to photograph the scan. Due to the geometry of the camera, two 30 cm-focal-length lenses in an 4-f configuration were needed to transfer the image, found at the back focal plane of the 10 cm lens, into the camera. After exiting the second 30 cm-focal-length lens, the light falls directly onto the film. Direct imaging of the display onto film eliminates speckle, commonly found in laser projection systems. Speckle is caused by optical interference in the light scattered from a projection screen due to roughness of the screen surface. To increase the rigidity of the tilt-up frames, all stationary hinge joints are preferably epoxied, with the exception of two joints at the base of the slow mirror frame. Epoxy was not applied to these stationary hinges because the adhesive could potentially spread to nearby actuator members, causing them to freeze in position. An acousto-optic modulator in the beam path adjacent to the laser source (element 42 in FIGS. 2 and 3) switches the light on-and-off with a signal that is synchronized to the mirror driving voltages. The acousto-optic modulator turns off the light in a narrow region (about 7% of the display width) at each edge of the horizontal scan. This non-linear turnaround region of the fast-mirror is not used for image display. A mechanical shutter 46 selects a half-cycle of the slow mirror to expose the film. The corrected optical beam size in the center of the image plane was within 12% of the theoretical diffraction-limited prediction. The smallest pixel size is at the center of the display, with no voltage applied to the actuators. If the display were filled with pixels of this size, its resolution would be 176 by 176. Accounting for the turn-around region on the horizontal scan, the resolution is 151 by 176. However, the pixel size varies according to mirror angle. The highest-resolution region in the image plane is a rectangle running the full height of the display and covering about 25% of the horizontal scan width. In this portion of the display, there is little deviation of the optical beam size from its minimum. Outside of this area, the scan lines become blurred. At the extreme edges of the display, the far-field beam size expands by roughly a factor of 2.5. By linear approximation, the laser beam expands in size by an average factor of 1.75 over 75% of the display. The horizontal display resolution can be approximated based on average pixel size to be 0.86*176*(0.25+0.75/1.75)=102 pixels. This average pixel size is used to define the horizontal line spacing because the optical beam is essentially circularly symmetric. Therefore, the vertical resolution based on average pixel size is approximately 176*(0.25+0.75/1.75)=119, because the fast and slow mirrors rotate through the same angle. There is effectively no resolution loss to turn-around regions in the slow-mirror scan because it is driven by a triangular waveform. Several raster-scanned images were photographed to demonstrate the display system. Dynamic effects, such as jitter and wobble, degrade the image quality. Jitter in the slow mirror causes bright horizontal lines, resulting from overlapping line scans. Three effects play a role in expansion of the far-field optical beam size at the end of the fast mirror scan line: static mirror deformation, dynamic mirror deformation, and wobble of the fast mirror. Wobble amplitude in the single-chip design appears to be less than the average pixel width. Sub-harmonic wobble was found in the two-chip raster-scanner, which is discussed below. A second optical raster-scanning system was tested independently of the single-chip scanner. The two-chip raster-scanner makes use of two fast mirrors oriented with orthogonal scan axes, as shown in FIG. 3 . One of the fast mirrors performs the same function as the slow mirror in the single-chip design. In this embodiment, none of the tilt-up frames were epoxied. The fast and slow-moving mirrors were operated at 5.3 and 5.7 degrees of optical deflection, respectively. Both mirror frames were tilted back with an angle of approximately 7 degrees from the perpendicular. The curvature-correction optics described in the previous section are used with the exception of the cylindrical lens. An optical assembly 60 with two 6.29 cm-focal-length lenses in a 4-f configuration is inserted between the mirrors to image the fast mirror onto the slow-moving mirror. These lenses could also be used to correct for mirror curvature. The output optics consists of a 30 cm-focal-length lens. The camera is positioned at the back-focal-plane of the output lens. The corrected far-field optical beam size in the image plane is 17% larger than the predicted diffraction limit. Compared to the single-chip design, a proportionally smaller region of the image is affected by curvature due to actuation because the scan angle is smaller. The resolution based on average pixel size is estimated to be 61 by 65 pixels. Jitter of the slow-moving mirror in the two-chip system is less prominent than in the single-chip display. The basic mechanical design of the fast mirror, when used as a slow-moving mirror in the two-chip display, may have superior jitter characteristics over the slow mirror design in the single-chip display. The fast-mirror wobble amplitude in the two-chip display, however, is significantly greater than the corresponding wobble amplitude found in the single-chip design. This may be due to more motion of the supporting frames because they were not epoxied in place. The wobble amplitude is greater than the horizontal line separation and the wobble frequency is lower than the rotational frequency of the fast mirror. When the system is operating as a display, the acousto-optic modulator selects the upper half-cycle of each line-scan, selectively switching the light off as the mirror wobbles. Mirror wobble in the two-chip system also interleaves the scan lines, causing the horizontal lines from top-to-bottom to be drawn out of sequence. To display the raster-image data in the correct sequence, every-other line-scan half-cycle was selected by the acousto-optic modulator. To maintain proper line spacing in this situation, the slow-scanning mirror frequency must be reduced by half. In sum, an improved surface-micromachined raster-scanning display has been disclosed. The apparatus has been implemented with a resolution of 151 by 176 pixels, and an average resolution of 102 by 119 pixels in a single-chip system. The tilt-up polysilicon mirror design allows for large mirror size and deflection, both shown to be necessary for high-resolution displays. Mirror curvature was found to be the primary factor that reduces resolution in micromachined scanners. The mirror curvature was characterized by measuring the far-field intensity distributions for a series of incident optical beam sizes and fitting the data to a theoretical curve. Information gathered from this technique determines the configuration of curvature-correcting optics that pre-form the optical beam incident on the scanners. This method successfully reduced the laser beam radius in the image plane of the single-chip raster scanner by more than an order of magnitude, bringing it to within 12% of the theoretically-predicted diffraction limit. Once the static mirror curvature was corrected, the factors limiting resolution and image quality were actuation-induced bending, jitter and wobble of the scanning mirrors. Modifying the fast mirror design by removing the direct connection of the comb-drive to the bottom of the mirror is expected to increase the resolution of the display. Deformation of the mirror can be avoided by connecting the comb-drive to the mirror through separate polysilicon beams that attach to the edges of the mirror near its rotational axis. To reach VGA resolution, the mirrors must increase in size and tilt-angle, and the resonant frequency of the fast mirror should be boosted. Maximizing the mechanical force output of the comb-drive actuators will be required to reach a sufficiently high resonant frequency. It is likely that stiffening of the fast-mirror surface to reduce dynamic bending will also be necessary. Those skilled in the art will appreciated that the disclosed technology can be used in light-weight, low-power, and low-cost video displays. For a flicker-free video display, the slow mirror should operate between 30-100 Hz. The video line-scan rate should be between 30-100 kHz. In the demonstrated single-chip display, one line is drawn for each half-cycle of the fast mirror, and no lines are drawn during half of the low mirror cycle. If information is displayed during both half-cycles of the fast and low mirrors, the effective line-scan rate (the number of lines drawn during one slow mirror cycle) increases by a factor of four. A 10 kHz fast-mirror that has already been demonstrated could produce an equivalent line-scan rate of 40 kHz, which is sufficient to display video. The following mechanical enhancements will improve system performance: increasing rotational angle and size of the mirror enables higher resolution displays, increasing the stiffness of the mirror springs increases the line-scan rate, and increasing the mirror stiffness ensures uniform pixel size across the display. Those skilled in the art will appreciate that a variety of techniques may be used to measure mirror curvature. A mirror may be placed in a device designed to measure the mirror curvature. The far-field characteristics of an optical beam reflected off of a micro-mirror can be used to compute the mirror curvature. The instruments used to measure the far-field optical beam size may be placed anywhere in the far-field (this can be advantageous) at a known distance from the mirror, and only one measurement may be required. From these measurements, the mirror curvature can be theoretically extracted and used to design corrective optics. The corrective optics may be placed before, between, or after the mirrors. In some cases it may be advantageous to place lenses in two or all three locations. In the case of a micro-display system, it may be advantageous to place all of the optics after the mirror system to minimize the number of micro-lenses that need to be mounted on the chip. It is not necessary to remove a micro-mirror from the display system to measure micro-mirror curvature. Corrective optics can be optimized for the curvature of an individual mirror by adjusting lens positions or adjusting the placement of the projection screen in the display system, using the display system laser as the measurement beam. This process finds the mirror curvature and tunes the corrective optics at the same time, potentially simplifying the process of building a working display. Placement of bulk mirror-curvature correction optics that lie external to the microscopic system may be used in manufacturing micro-displays. In such a case, the light source and mirrors are assembled on a substrate and are incorporated into a package, without the need to customize the optics in the package. Mirror curvature correction is performed later with a macroscopic lens. Mirror curvature can be corrected by appropriate selection of the output optics, optimum placement of the display screen, or a combination of the two. There are numerous causes of mirror curvature, including stress-gradients, thermal expansion and contraction, static, dynamic, and inertial forces. A system can be engineered to cancel the combined effect of mirror curvature in both mirrors without inclusion of external curvature-correcting optics. A convex mirror immediately following a concave mirror with the same absolute radius of curvature can be used to cancel the effect of mirror curvature. Similarly, a concave mirror followed by a convex mirror with the same absolute radius of curvature cancels the curvature effect. In micromachined systems, curvature due to stress-gradients is often uniform over the small region of the substrate on which the display is fabricated. By fabricating one mirror with its optical surface facing down, and the other mirror with its optical surface facing up (before assembly), the mirrors have opposite concavity after release. After release and assembly, one mirror is convex and the other concave. The divergence or convergence that the first mirror induces in the reflected optical wavefront is largely canceled after reflection from the second mirror. The foregoing description, for purposes of explanation, used specific nomenclature to provide a thorough understanding of the invention. However, it will be apparent to one skilled in the art that the specific details are not required in order to practice the invention. In other instances, well known circuits and devices are shown in block diagram form in order to avoid unnecessary distraction from the underlying invention. Thus, the foregoing descriptions of specific embodiments of the present invention are presented for purposes of illustration and description. They are not intended to be exhaustive or to limit the invention to the precise forms disclosed, obviously many modifications and variations are possible in view of the above teachings. The embodiments were chosen and described in order to best explain the principles of the invention and its practical applications, the thereby enable others skilled in the art to best utilize the invention and various embodiments with various modifications as are suited to the particular use contemplated. It is intended that the scope of the invention be defined by the following claims and their equivalents.

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CROSS REFERENCE TO RELATED APPLICATIONS [0001] This application claims priority to U.S. Provisional Patent Application No. 60/178,627 entitled “Alerting Users To Web Sites Of Current Interest And Handling Large Increases In User Traffic” filed Jan. 28, 2000 which is incorporated herein by reference for all purposes. [0002] This application is related to co-pending U.S. patent application Ser. No. ______ (Attorney Docket No. INT1P209) entitled “Quantifying The Level Of Interest Of An Item Of Current Interest” filed concurrently herewith, which is incorporated herein by reference for all purposes; and co-pending U.S. patent application Ser. No. ______ (Attorney Docket No. INT1P210) entitled “Normalizing A Measure Of The Level Of Current Interest Of An Item Accessible Via A Network” filed concurrently herewith, which is incorporated herein by reference for all purposes. FIELD OF THE INVENTION [0003] The present invention relates generally to communications and computer networks. More specifically, alerting users to dynamic content accessible via a communications or computer network that is of interest at the time of the alert is disclosed. BACKGROUND OF THE INVENTION [0004] The use of the Internet, and in particular the World Wide Web, and other communication and computer networks has grown dramatically in recent years. The emergence of technologies for broader bandwidth communications, better compression technology, and new and less expensive digital recording and imaging technology, have all contributed to explosive growth in the volume and diversity of content available via communication and/or computer networks, such as the World Wide Web. [0005] However, this proliferation of content, such as audio, image, and video content, presents certain challenges from the perspective of users seeking content of current interest. First, the shear volume of content available makes it difficult for users to find the content in which they are most interested in accessing at any given time. Apart from having to sort through the enormous volume of content available, much of the content of potentially greatest interest, at least to many users, is dynamic. At certain times, a file or other electronic resource may be of great interest while at other times, or perhaps even most of the time, it is not of great interest or not interesting at all. [0006] For example, thousands of and perhaps in excess of a hundred thousand web cameras, or “webcams”, are in use. Webcams are cameras used to provide images of a target of interest via a site on the World Wide Web. Images are updated in varying manners and at varying intervals, depending on the site. A webcam might be used, for example, to provide images of a watering hole in Africa. Typically, users would access a website associated with the webcam to view activity at the watering hole. However, there would be many periods during which nothing of particular interest (e.g., no animals, etc.) would be happening at the watering hole. Conversely, there would be occasional periods when activity of great interest would be occurring, such as the presence of a rare or endangered animal at the watering hole. Users would have no way of knowing when such activity would be occurring, and might miss the most interesting images if they did not happen to check the website at the right time. The same problems arise with respect to files or other electronic resources other than webcam content provided via the World Wide Web, including other media such as audio. [0007] As a result, there is a need for a way to alert users to web content or other electronic resources available via a communications or computer network that are of interest at a particular time. To meet this latter need, there is a need to provide a way to become aware that dynamic web content or an electronic resource other than web content is of interest at a given time, and to quantify the degree or level of current interest. In addition, there is a need to consider the interests of a user when determining which web content or other electronic resources likely will be of the greatest interest to the user. [0008] There is also a need to ensure that interested users receive alerts with respect to web content or other electronic resources that are of interest only to a relatively small community of users, or that are of interest on only relatively rare or infrequent occasions. There is a risk, otherwise, that indications of current interest regarding such files and other electronic resources would be masked by more voluminous or frequent activity with respect to more widely popular or pervasive resources or types of resources (such as pornography sites on the World Wide Web). SUMMARY OF THE INVENTION [0009] Accordingly, alerting users of items of current interest is disclosed. The level of current interest of a particular file or other electronic resource is determined based on indications received from alerting users. One or more users receive an alert that the item is of current interest. Normalization of the level of current interest of a file or other resource, such as to adjust for items of current interest to a small community or for items of current interest only infrequently, also is described. [0010] It should be appreciated that the present invention can be implemented in numerous ways, including as a process, an apparatus, a system, a device, a method, or a computer readable medium such as a computer readable storage medium or a computer network wherein program instructions are sent over optical or electronic communication links. Several inventive embodiments of the present invention are described below. [0011] Disseminating to a participant an indication that an item accessible by the participant via a network is of current interest is disclosed. In one embodiment, an indication that the item is of current interest is received in real time. The indication is processed. The participant is informed that the item is of current interest. [0012] In one embodiment, a computer is configured to receive in real time an indication that an item is of current interest; process the indication; and inform a participant that the item is of current interest. A database, associated with the computer, is configured to store data relating to the item. [0013] In one embodiment, a computer program product for disseminating to a participant an indication that an item accessible by the participant via a network is of current interest comprises computer instructions for receiving in real time an indication that the item is of current interest; processing the indication; and informing the participant that the item is of current interest. [0014] These and other features and advantages of the present invention will be presented in more detail in the following detailed description and the accompanying figures, which illustrate by way of example the principles of the invention. BRIEF DESCRIPTION OF THE DRAWINGS [0015] The present invention will be readily understood by the following detailed description in conjunction with the accompanying drawings, wherein like reference numerals designate like structural elements, and in which: [0016] [0016]FIG. 1 is a schematic diagram illustrating a system used in one embodiment to alert users to dynamic content of interest at the time of the alert (also referred to herein as an “item of current interest”). [0017] [0017]FIG. 2A is a series of three screen shots showing three different states of an alert submission display 200 used in one embodiment. [0018] [0018]FIG. 2B is an illustration of the data structure used in one embodiment for alerts submitted by an alerting user. [0019] [0019]FIG. 3 is a flow chart illustrating a process used in one embodiment to alert users of items of current interest. [0020] [0020]FIG. 4 is a flow chart illustrating a process used in one embodiment to receive an alert, as in step 302 of FIG. 3. [0021] [0021]FIG. 5 is an illustration of the data structure used in one embodiment for the alert object. [0022] [0022]FIG. 6 is a flowchart illustrating a process used in one embodiment to process an alert, as in step 304 of FIG. 3. [0023] [0023]FIG. 7 is an illustration of six database tables 700 used in one embodiment to store data concerning alerts received with respect to items of current interest associated with URLs. [0024] [0024]FIG. 8A is a flowchart illustrating a process used in one embodiment to update the intensity sum for a URL, as in step 606 of FIG. 6. [0025] [0025]FIG. 8B is a flowchart illustrating a process used in one embodiment to update the intensity rank for a URL to reflect the intensity of the current alert. [0026] [0026]FIG. 8C is a flowchart illustrating a process used in one embodiment to update the interest category weight for a URL with respect to the interest category indicated in an alert. [0027] [0027]FIG. 9 is a flowchart illustrating a process used in one embodiment to purge records for URLs that are determined to be no longer of current interest by calculating a time decayed intensity rank at intervals, even if no new alert has been received, and purging from the database the records for a URL if the time decayed intensity rank is below a prescribed threshold. [0028] [0028]FIG. 10 is a flowchart illustrating a process used in one embodiment to disseminate an alert to a participant, as in step 306 of FIG. 3. [0029] [0029]FIG. 11 shows an exemplary participant display 1100 used in one embodiment to disseminate alert information to a participant. [0030] [0030]FIG. 12 is a flowchart illustrating a process used in one embodiment to build a list of hot URLs responsive to a request, as in step 1008 of FIG. 10. DETAILED DESCRIPTION [0031] A detailed description of a preferred embodiment of the invention is provided below. While the invention is described in conjunction with that preferred embodiment, it should be understood that the invention is not limited to any one embodiment. On the contrary, the scope of the invention is limited only by the appended claims and the invention encompasses numerous alternatives, modifications and equivalents. For the purpose of example, numerous specific details are set forth in the following description in order to provide a thorough understanding of the present invention. The present invention may be practiced according to the claims without some or all of these specific details. For the purpose of clarity, technical material that is known in the technical fields related to the invention has not been described in detail so that the present invention is not unnecessarily obscured. [0032] [0032]FIG. 1 is a schematic diagram illustrating a system used in one embodiment to alert users to dynamic content of interest at the time of the alert (also referred to herein as an “item of current interest”). The system 100 includes at least one alerting user 102 who accesses dynamic content associated with a uniform resource locator (URL), determines the content is of current interest, and sends an alert indicating that the URL is of current interest, as described more fully below. The system 100 also includes at least one participant 104 . In one embodiment, participant 104 provides an indication of the participant's interests and receives a list of URLs providing the location of dynamic content, such as web content on the World Wide Web, that may be of interest to the participant at the time of the alert, as described more fully below. Both the alerting user 102 and the participant 104 are connected to a web server 105 via the Internet. Web server 105 is a computer system configured to present web pages and other web browser readable file, and to receive data from users, via the World Wide Web. Web server 105 is connected to an application server 106 and is configured to provide data to and receive data and instructions from application server 106 . Application server 106 is configured to perform the application logic functions described more fully below. In one embodiment, the functions performed by the application server, as described more fully below, are divided among two or more computers so as to optimize the distribution of work load among the computers and to minimize the time the system takes to respond to inputs and queries from users. [0033] When an alert has been received and is being processed, as described more fully below, the application server 106 comprises an alert software object 108 used to store data relating to and perform certain processing with respect to an alert, as described more fully below. The alert software object 108 uses data provided in an alert sent by alerting user 102 , along with data retrieved from database 110 associated with the application server 106 , to process the alert. Certain of the data that results from the processing performed by alert software object 108 is then stored in database 110 . In one embodiment, database 110 is stored in memory in application server 106 . In one embodiment, database 110 is stored in a separate structure, such as a database server, connected, either directly or through a communication link, with application server 106 . [0034] In one embodiment, when a request from a participant for a list of URLs for items of current interest is received, the application server 106 comprises a hot list software object 112 used to store certain data concerning and perform certain operations with respect to the request from the participant and the response thereto. In one embodiment, the hot list object 112 comprises an interest category array 114 . In one embodiment, the interest category array 114 is comprised of one or more interest category objects, each of which stores data relating to one interest category identified in the participant's request as being of interest to the participant. In one embodiment, the hot list object 112 comprises a hot token array 116 . The hot token array 116 is comprised of a hot token object for each URL of current interest in the database for the category or categories indicated in the participant's request. [0035] As indicated in FIG. 1, an alert sent by an alerting user includes, in one embodiment, at least the URL of the web content considered by the alerting user to be of current interest. In one embodiment an alert may also include an interest selection, meaning a category or subject area to which the alerting user believes the web content relates, and/or a caption in which the alerting user may provide text indicating what the alerting user believes to be of current interest in the web content. [0036] [0036]FIG. 2A is a series of three screen shots showing three different states of an alert submission display 200 used in one embodiment. One view is comprised of blank alert submission display 202 . Blank alert submission display 202 includes a submission button 204 used to submit an alert with respect to the URL of the web content currently being accessed by the alerting user. Blank alert submission display 202 also includes an interest category selection area 206 . In one embodiment, as illustrated in FIG. 2A, the interest category selection area 206 is configured as a pull down menu activated by selecting the downward arrow on the right side of interest category selection area 206 . Blank alert submission display 202 also includes a caption area 208 in which an alerting user may enter text associated with the alert, such as text indicating why the alerting user believes the URL to be of current interest. As shown in interest category selection display 212 , when the downward arrow button on the right side of interest category selection area 206 is selected, a pull down menu 214 is presented, and an alerting user may select one of the interest categories listed in the pull down menu 214 in the manner well known in the art. As shown in the completed alert submission display 222 of FIG. 2A, the interest category selected by the alerting user is shown in the interest category selection area 206 . In the example shown in FIG. 2A, the category selected is “NATURE”. In addition, the caption entered by the alerting user, the comment “rhino!” in the example shown in FIG. 2A, appears in the caption area 208 of the alert submission display. As noted above, the alerting party posts the alert to the application server via the Internet and the web server by selecting the submission button 204 . [0037] [0037]FIG. 2B is an illustration of the data structure used in one embodiment for alerts submitted by an alerting user. The alert includes an ALERTER_ID field 240 in which data identifying the alerting user is provided. The alert also includes a URL field 242 in which the URL of the web content or other electronic resource being accessed by the alerting user when the alert was sent is stored. The alert also includes an INTEREST SELECTION field 244 in which the interest category selected by the alerting user, if any, is provided. Finally, the alert includes a CAPTION field 246 in which the caption entered by the alerting user, if any, is provided. [0038] [0038]FIG. 3 is a flow chart illustrating a process used in one embodiment to alert users of items of current interest. The process begins in step 302 in which an alert indicating that an item is of current interest is received. Next, in step 304 , the alert is processed. Finally, in step 306 , the alert is disseminated to one or more participants, as described more fully below. [0039] [0039]FIG. 4 is a flow chart illustrating a process used in one embodiment to receive an alert, as in step 302 of FIG. 3. The process begins with step 402 in which a transmission comprising an alert is received from an alerting user. As noted above, in one embodiment an alert includes at least the URL of the web content being accessed by the alerting user at the time the alert was sent. In one embodiment, as described above, the alert also includes data indicating the identity of the alerting user. In addition, as noted above, the alert may include, at the option of the alerting user, an interest selection and/or a caption for the alert. The process shown in FIG. 4 continues with step 404 in which a new alert software object is created at the application server, such as application server 106 of FIG. 1. Next, in step 406 , the data provided in the alert is stored in the alert object. In step 408 , a time stamp indicating the time when the alert was received is stored in the alert object. Finally, in step 410 , an ALERT_ID, which uniquely identifies the alert and distinguishes the alert and its associated object from other alerts and their associated objects, is obtained and stored in the alert object. [0040] [0040]FIG. 5 is an illustration of the data structure used in one embodiment for the alert object. Data field 502 is used to store the ALERT_ID described above. Data field 504 is used to store the time stamp described above. Data fields 506 - 512 are used to store the ALERTER_ID, URL, INTEREST SELECTION, and CAPTION described above, respectively. ALERT INTENSITY field 514 is used to store a number indicating the intensity or weight to be afforded to the incoming alert. The ALERT INTENSITY is determined as described below. The alert object also stores properties retrieved from various database tables, described more fully below. For example, the alert object includes a LAST_TIME field 516 used to store data retrieved from the database indicating the time of the most recent prior alert. The alert object also includes an LAST_RANK field 518 used to store a numerical ranking retrieved from the database that indicates the overall level or degree of current interest of an item as indicated by all of the alerts that have been submitted with respect to a URL during the current period of activity with respect to the URL through the most recent prior alert. The alert object also includes a LAST_WEIGHT field 520 used to store data retrieved from a database table, as described below, that represents the number of prior alerts received for the URL in the interest category indicated by the current alert, as described more fully below. The alert object also includes a LAST_INTENSITY_SUM field 522 in which the sum of the intensities of all prior alerts for the URL during the current period of activity with respect to the URL, which sum is retrieved from a database table described more fully below, is stored. Finally, the alert object includes a LAST_NORMAL_TIME field 524 used to store the time, retrieved from a database table as described more fully below, when the last normalization calculation was performed. [0041] [0041]FIG. 6 is a flowchart illustrating a process used in one embodiment to process an alert, as in step 304 of FIG. 3. The process begins with step 602 in which the intensity of the alert is determined. The term intensity as used herein refers to the weight or value to be assigned to a particular alert regarding an item. In one embodiment, the intensity is a value between 0 and 1. In one embodiment, the value assigned for the intensity is higher if the alerting user selects an interest category for the alert than it would have been if the same alerting party had not selected an interest category. In one embodiment, the intensity value is higher if the alerting party provides a caption for the alert than it would have been if the alerting party had not provided a caption. In one embodiment, the intensity of an alert is increased if it is determined that the alerting party is a party that has provided particularly relevant or helpful alerts in the past, or is trusted for some other reason, such as expertise, academic credentials, or reputation within a particular community of interest. In one embodiment, the intensity of an alert is decreased if it is determined that the alerting party has provided unhelpful or erroneous alerts in the past, or if it is determined that the alerting party cannot be trusted as much as other alerting parties for other reasons, such as reputation in the relevant community. In one embodiment, it is possible to provide both an active alert by selecting an alert button and to provide a passive alert by merely accessing a URL with respect to which an alerting party previously submitted an active alert. In one embodiment, an active alert is assigned a higher intensity value than a passive alert. [0042] For example, a passive alert may be arbitrarily assigned a baseline intensity value of 0.3 and an active alert a baseline intensity value of 0.5. For an active alert, 0.1 could be added for each of the following conditions that is satisfied by the alert: an interest category selection was included in the alert; a caption was included in the alert; and/or the source of the alert is particularly trusted. Conversely, 0.1 could be subtracted from the intensity of an alert from a source known to be unreliable. Alternatively, alerts from sources known to be unreliable may be blocked and not assigned any intensity value. [0043] The process illustrated in FIG. 6 continues with step 604 in which data values for the alert object data fields described above that are not included in the alert transmission received from the alerting party are retrieved from the database. [0044] Next, in step 606 , the intensity sum for the URL, which is the sum of the intensity values for all of the alerts with respect to the URL, is updated. Next, in step 608 , the intensity rank for the URL is updated to reflect the new alert. In step 610 , the interest weight value, which represents the number of alerts for a particular URL in which a particular category of interest was indicated, is updated. Finally, in step 612 , the updated data values are stored to the database. [0045] [0045]FIG. 7 is an illustration of six database tables 700 used in one embodiment to store data concerning alerts received with respect to items of current interest associated with URLs. The database tables 700 include an INTEREST_ID table 702 used to provide a unique identifier, labeled INTEREST_ID in FIG. 7, for each interest category, denominated INTEREST_CAT in FIG. 7. Database tables 700 also include a URL_ID table 704 used to provide a unique identifier, labeled URL_ID in FIG. 7, for each URL. [0046] Database tables 700 also include an INTERESTS table 706 used to store the interest weight, denominated WEIGHT in FIG. 7, for each interest category with respect to which an alert has been submitted for a URL. As noted above, in one embodiment, the weight is the total number of alerts received within a given interest category for a URL. For example, if five alerts indicating the interest category People and three alerts indicating the interest category Nature have been submitted for a URL, there will be two entries for the URL in the interest table, one for each interest category. The weight in the entry for the category People would be “5” and the weight for the URL in the category Nature would be “3”. [0047] The database tables 700 also include a RANK, table 708 used to store a rank value for each URL associated with an item of current interest, a time stamp when the rank was last calculated, and a data entity denominated NUM_ALERT in FIG. 7, which represents the total number of alerts submitted for the URL. [0048] The database tables 700 also include a COMMENTS table 710 used to store any comment submitted with an alert and to associate each comment with the corresponding URL. Finally, the database table 700 include a NORMALIZE table 712 used to store the sum of the intensities of the alerts submitted for a URL (INTENSITY_SUM) and a time stamp indicating when the last normalization was performed. [0049] [0049]FIG. 8A is a flowchart illustrating a process used in one embodiment to update the intensity sum for a URL, as in step 606 of FIG. 6. The process begins with step 802 in which the current intensity sum is retrieved from the database, as in step 604 of FIG. 6. If there is no existing record for the URL in the NORMALIZE table (i.e., the alert being processed is the first alert for the URL), a URL_ID is assigned for the URL, a record for the URL is created in the NORMALIZE table, and the retrieved current intensity sum is set to zero. Next, in step 804 , the intensity sum is incremented by the amount of the intensity of the current alert. For example, if the previous intensity sum was 4.7 and the intensity for the current alert was 0.5, the intensity sum would be incremented to the value of 4.7+0.5=5.2. Finally, in step 806 , the intensity sum time stamp stored in NORMALIZE table 712 shown in FIG. 7 (which is the same as the LAST_NORMAL_TIME stored in field 524 of FIG. 5) is updated to the time stamp of the current alert. In one embodiment, the intensity sum is updated, and a normalization is performed as described more fully below, each time a new alert is received for a URL. In such an embodiment, the time stamp stored in the NORMALIZE table 712 of FIG. 7 will be the same as the time stamp stored in the RANK table 708 of FIG. 7, as both the rank and the intensity sum are updated each time an alert is received. [0050] [0050]FIG. 8B is a flowchart illustrating a process used in one embodiment to update the intensity rank for a URL to reflect the intensity of the current alert. The process begins with step 822 in which the current intensity rank is retrieved from the database, as in step 604 of FIG. 6. As shown in FIG. 7, in one embodiment, this value is retrieved from the RANK table 708 . If there is no entry in the RANK table for the URL, i.e., the alert being processed is the first alert for the URL, a record in the RANK table is created for the URL (identified by the URL_ID assigned to the URL) and the current intensity rank is set to zero. Next, in step 824 , the intensity rank is updated to reflect the intensity of the current alert. In one embodiment, if the current alert has been received within a predetermined time interval τ after the last alert for the URL, the updated intensity rank is a function of the last rank and the intensity of the current alert in accordance with the following formula: r ′=( k−r )* I alert +r [0051] Where k is the maximum intensity value, which as noted above is one in one embodiment, r is the last rank, r′ is the updated rank, and I alert is the intensity value for the current alert. Restating the formula to reflect the fact that in one embodiment, the maximum intensity level k=1, the formula becomes: r ′=(1 −r )* I alert +r [0052] If an alert is the first alert received for a URL, the last rank is considered to be zero (r=0) and the above formula results in the new rank being equal to the intensity value for the current alert. For example, if the intensity value for the current alert is 0.5, the updated heat rank r′=(1−0)*0.5+0=0.5. If a subsequent alert of intensity 0.6 is received, the formula results in the updated intensity rank being calculated as follows: r ′=(1−0.5)*0.6+0.5=0.8 [0053] As the example illustrates, so long as additional alerts are received within the time interval each incoming alert will cause the intensity rank for the URL to increase until the intensity rank approaches the maximum intensity value k (in the example, the rank would approach k=1). The speed with which the intensity rank for a particular URL approaches the maximum value k depends on the intensity value of the incoming alerts and the frequency with which alerts are received. [0054] In one embodiment, if the predetermined time interval τ referred to above has expired between the last alert and the current alert, the updated intensity rank is calculated by a modified formula which reduces the updated intensity rank in accordance with an exponential decay function that effectively adjusts the updated intensity rank downward to account for the passage of time between the last alert and the current alert. All other things being equal, this adjustment would result in a site that received alerts more frequently to have a higher rank than a site that received alerts separated by more than the predetermined time interval. To determine the updated intensity rank as adjusted for the passage of time, the following formula is used in one embodiment: r ′=[( k−r )* I alert +r]*e −a(Δt−t) . [0055] In this formula, k, r, and I alert are the same as above, a is the weight assigned to the decay function (a higher value for a will result in a greater amount of decay per unit time), Δt is the amount of time that has elapsed between the current alert and the previous alert, and τ is the predetermined time interval referred to above. [0056] In one embodiment, the updated intensity rank is normalized by multiplying the updated intensity rank by two factors. The first factor is a low frequency enhancement factor designed to enhance the intensity rank of URLs with respect to which alerts are received relatively less frequently relative to the intensity rank of URLs regarding which alerts are received more frequently. The purpose of this enhancement factor is to ensure that sites that are of current interest only from time to time are not masked by the intensity ranking calculated for sites that are of current interest more frequently. In one embodiment, the low frequency enhancement factor is the time of the current alert minus the time of the last update to the intensity rank. [0057] The second factor by which the updated intensity rank is multiplied is a low volume enhancement factor The purpose of this factor is to ensure that the intensity rank of URLs that are of current interest only to a smaller community of users will not be overshadowed by the intensity rank of URLs that are of current interest to a large community. In one embodiment, the low volume enhancement factor is the inverse of the intensity sum for the URL. Accordingly, in one embodiment, the normalized intensity rank is determined by the following formula: r″=r ′*( t current −t first )*1 /n [0058] Where r″=normalized intensity rank [0059] r′=updated intensity rank before normalization [0060] t current =timestamp of current alert [0061] t first =timestamp of first alert for URL [0062] n=intensity sum=sum of all alert intensities for URL [0063] Once the intensity rank has been updated and normalized, the process shown in FIG. 8B continues with step 826 in which the time stamps for the normalization and intensity rank tables are updated to the time stamp of the current alert. [0064] [0064]FIG. 8C is a flowchart illustrating a process used in one embodiment to update the interest category weight for a URL with respect to the interest category indicated in an alert. The process begins with step 842 in which the database is queried to determine if a record exists for the URL for the interest category indicated in the alert. In step 844 , it is determined whether the query performed in step 842 identified an existing database table entry for the URL for the interest category indicated in the alert (i.e., whether a prior alert indicated the same interest category for the URL). If it is determined in step 844 that a database entry does not exist for the interest category with respect to the URL, the process proceeds to step 846 in which a record in the INTEREST table is created for the URL with respect to the interest category of the alert. The process then proceeds to step 850 in which the weight value is incremented for the URL with respect to the interest category by increasing the value from zero to one for the new record. [0065] If it is determined in step 844 that there is an existing record for the interest category for the alert with respect to the alert URL, the process proceeds to step 848 in which the weight value stored in the record is retrieved. The process then continues to step 850 in which the retrieved weight is incremented by one to reflect the current alert. For example, if the retrieve weight were 7, the weight would be incremented to 8 in step 850 to reflect the current alert. [0066] [0066]FIG. 9 is a flowchart illustrating a process used in one embodiment to purge records for URLs that are determined to be no longer of current interest by calculating a time decayed intensity rank at intervals, even if no new alert has been received, and purging from the database the records for a URL if the time decayed intensity rank is below a prescribed threshold. The process shown in FIG. 9 begins with step 902 in which the intensity rank for a URL is retrieved. In one embodiment, the intensity rank is retrieved and process shown in FIG. 9 is performed, at a predetermined arbitrary time interval τ. [0067] The process shown in FIG. 9 continues with step 904 in which an intensity rank adjusted for time decay is calculated for the URL. In one embodiment, the time decayed intensity rank is determined by the following formula: r t =e −a(Δt−r) *r [0068] Where [0069] r t =time decayed intensity rank [0070] a=weight of decay function [0071] Δt=time elapsed since last alert [0072] τ=predetermined time interval referred to above [0073] r=stored intensity rank [0074] As can be seen from the above formula, the time decayed intensity rank decays exponentially over time if no new alerts are received. If it is determined in step 906 of the process shown in FIG. 9 that the time decayed intensity rank is below the intensity rank threshold, the process proceeds to step 908 in which the record for the URL is deleted. If it is determined in step 906 that the time decayed intensity rank is not below the intensity rank threshold, the process proceeds to step 910 in which the intensity rank as stored in the database is left unchanged. [0075] [0075]FIG. 10 is a flowchart illustrating a process used in one embodiment to disseminate an alert to a participant, as in step 306 of FIG. 3. The process begins with step 1002 in which a request containing interest category filter selections made by the participant is received. Next, in step 1004 , a hot list software object is created at the application server, as shown in FIG. 1 and described above. Then, in step 1006 , an array of interest categories, such as the interest category array 114 described above with respect to FIG. 1, is created within the hot list object. Next, in step 1008 , a list of hot URLs responsive to the request is built. Finally, in step 1010 , the list of hot URLs responsive to the request is sent to the participant. [0076] [0076]FIG. 11 shows an exemplary participant display 1100 used in one embodiment to disseminate alert information to a participant. The display 1100 includes a URL entry and display area 1102 . The URL for the web content or other electronic resource currently being accessed by the participant is displayed in the URL entry and display area 1102 , and the participant may enter the URL for the web content or other electronic resource the participant wishes to access manually in the URL entry and display area 1102 , as in the URL or address field for a World Wide Web browser. The display 1100 also includes a content display area 1104 in which the web or other content for the URL listed in URL entry and display area 1102 is displayed. For example, if the URL is the URL of web content accessed via the Internet, the web content associated with the URL will be displayed in URL display area 1104 . [0077] The display 1100 also includes an interest category filter selection area 1106 in which interest categories are listed along with a check box for each category listed. The participant selects the check box for each interest category for which the participant would like URLs of current interest to be included in the participant's hot list. [0078] In one embodiment, filter selection area 1106 includes for each category a sensitivity entry area (not shown in FIG. 11) to be used to provide an indication of the participant's degree or level of interest. For example, in one embodiment a participant may enter a whole number from 1 to 5, with 1 indicating the lowest level of sensitivity (e.g., the participant does not want to receive a notification regarding a URL in the category unless a significant number of alerts have been received regarding the URL, or only when the intensity rank for the URL exceeds a predetermined, relatively high threshold) and 5 representing the highest level of sensitivity (e.g., the participant wants to receive a notification even if there has only been one or relatively few alerts concerning a URL, or if one or more alerts have been received but the intensity rank for the URL is relatively low). [0079] In one embodiment, a request is sent to the application server automatically at predetermined intervals. The request contains the interest categories that are in the selected state at the time the request is sent. In one embodiment, the display 1100 includes a submit button (not shown in FIG. 11) that, when selected, causes a request containing the interest categories selected by the participant at the time to be posted to the application server via the Internet. [0080] The display 1100 also includes a hot list display area 1108 in which the hot list of URLs returned by the system to the participant in response to a request is presented. As shown in FIG. 11, in one embodiment, each URL is represented by a hypertext link that, when selected, causes the URL of the listed cite to appear in the URL entry and display area 1102 and the content associated with the URL to be displayed in the URL display area 1104 . [0081] In one embodiment, the display 1100 is modified to include an alert submission display area such as the alert submission display shown in FIG. 2A. This would permit a participant to send an active alert to the application server if the participant encounters a URL of current interest. [0082] [0082]FIG. 12 is a flowchart illustrating a process used in one embodiment to build a list of hot URLs responsive to a request, as in step 1008 of FIG. 10. The process begins with step 1202 in which all URLs of current interest within the categories indicated in the request are found. [0083] Next, in step 1204 , a “hot token” object is created in a hot token array within the hot list object for each URL found in step 1202 , as described above with respect to hot token array 116 shown in FIG. 1. Each hot token object holds the URL_ID, the WEIGHT for the URL with respect to the interest category indicated in the request, the sum of the WEIGHT values for each category associated with the URL in the database, and the intensity rank (RANK) for the URL. [0084] Next, in step 1206 , a list rank is determined for each URL retrieved in response to the request. In one embodiment, a list rank value is calculated for each URL and is used to determine the list rank (or the order in which the responsive URLs will be placed to determine which URLs will be provided). In one embodiment, an initial list rank value is calculated for each URL based on the interest category weight(s) for the URL with respect to the interest category or categories in the request, along with the interest weight for any interest category or categories that are associated with the URL in the database but which are not among the categories indicated in the request. In one embodiment, the initial list rank value “v” of a URL number “n” (v n ) is calculated according to the following formula: v n = ∑ f k ∑ f m [0085] Where v n =initial list rank value of URL “n” [0086] f k = =interest weight for URL for each request category [0087] f m =interest weight for each category associated with URL in database [0088] For example, if at the time of the request there had been ten alerts submitted for a particular URL and three of the alerts were associated with a first category, two with a second category and five with a third category, and if a request were received that included among the request categories the first and third categories, the initial list rank value “v” for URL number “n” calculated in accordance with the above formula would be as follows: v n = 3 +     5 3 + 2 + 5 ≈ 0.74 [0089] It should be noted that the use of the square root of the weight for each category tends to give relatively greater effect to the weight of interest categories associated with the URL by a minority of alerting users because using the square root reduces the net effect of the greater weight value associated with interest categories indicated by the majority of alerting users. As with the normalization of the intensity rank described above, this has the effect of giving more visibility to matters of interest to a relatively smaller community. [0090] In an embodiment in which the participant indicates a level of sensitivity with respect to each selected interest category, as described above, the formula for the initial list rank value is modified to take into consideration the sensitivity “s” indicated for each category of interest. In one embodiment, the initial list rank value formula is modified as follows: v n = ∑ s k * f k ∑ s m * f m [0091] Where v n =initial list rank value of URL “n” [0092] f k = =interest weight for URL for each request category [0093] f m =interest weight for each category associated with URL in database [0094] s k =sensitivity indicated for request category “k” [0095] s m =sensitivity indicated for request category corresponding to interest category “m”, if any (s m =1 for interest categories not in request). [0096] For example, in the example described above, assume the participant indicated a sensitivity level of 1 with respect to the first category and 5 with respect to the third category, the initial list rank value would be calculated as follows: v n = 1 * 3 + 5 * 5 1 * 3 + 1 * 2 + 5 * 5 ≈ 0.83 [0097] (As noted above, the sensitivity level s m used for the second category, having weight “2” in the denominator, is set at “1” because in the example the participant did not select that category.) [0098] The initial list rank value determined by this calculation (0.83) is greater than the initial list rank value found in the above calculation of an initial list rank value in an embodiment in which sensitivity levels are not assigned or considered (0.74). This illustrates the effect of assigning sensitivity levels. The initial list rank value determined in the second calculation, which takes into account a sensitivity level for each category, is higher than it would have been found to be without regard to sensitivity because the participant indicated a higher sensitivity for one of the categories with respect to which alerts had been received for the URL. [0099] In this way, high-sensitivity users are more likely to become aware of and access a URL with respect to which one or more alerts have been received in a category for which the user has indicated a high sensitivity. If such a high-sensitivity users chose to send alerts of their own with respect to the URL, such activity would increase the intensity rank for the URL (as described above) and would tend to propagate the original alert or alerts to lower-sensitivity users (because the intensity rank is factored into the final list rank used to identify the final list of URLs to be provided to a participant, as described below). If such lower-sensitivity users were to send even more alerts, the original alerts would be further propagated to even lower-sensitivity users, and so on. [0100] In one embodiment, the initial list rank value determined by the interest category weights, as described above, is used along with the intensity rank for the URL to calculate a final list rank value for the URL. In one embodiment, the final list rank value for URL number “n” is calculated in accordance with the following formula: v n ′=r n (α+(1−α) v n ) [0101] Where [0102] v n ′=final list rank value [0103] r n =intensity rank for URL [0104] α=weight factor (0≦α≦1) [0105] v n =initial list rank value [0106] In the above equation, the weight factor α determines the relative weight afforded to the intensity rank for the URL and the initial list rank calculated based on the interest category weights as described above. If the value for α is selected to be 1, the final list rank would be equal to the intensity rank for the URL and the initial list rank would not factor into the final list rank at all. Therefore, a higher weight factor will tend to increase the influence of the intensity rank for the URL and decrease the effect of the initial list rank. Stated another way, a low weight factor tends to give more effect to the extent to which the interest categories associated with the URL in the database match the interest categories indicated in the request from the participant. Conversely, a higher weight factor tends to give greater effect to the overall popularity of the URL as measured by the intensity rank. [0107] Once the list rank for each retrieved URL has been calculated in step 1206 , in step 1208 the retrieved URLs are sorted by list rank. Then, in step 1210 , the top ten URLs by list rank are selected as the hot list of URLs to be sent to the participant in response to the request. The number ten is an arbitrary number and either a fewer number or greater number of URLs may be included. [0108] Although the foregoing invention has been described in some detail for purposes of clarity of understanding, it will be apparent that certain changes and modifications may be practiced within the scope of the appended claims. It should be noted that there are many alternative ways of implementing both the process and apparatus of the present invention. Accordingly, the present embodiments are to be considered as illustrative and not restrictive, and the invention is not to be limited to the details given herein, but may be modified within the scope and equivalents of the appended claims.

4y

This is a division of application Ser. No. 07/545,941, filed Jun. 29, 1990, now abandoned. BACKGROUND OF THE INVENTION The present invention relates to an optical recording process which provides on a substrate a recording film having such optical properties as are variable by means of light, heat, and so forth and performs the recording, reproduction, and erasure of information through its utilization of changes in the said optical properties and more particularly to improvements an such an optical recording process so that it is capable of maintaining the recorded information over a long period of time. The principal parts of the optical recording medium used for this type of optical recording process are comprised, for example, of (a) a pre-groove for use in focusing and in tracking servo operation as shown in FIG. 49, (b) a light-transmissive substrate in which the said pre-groove (a) is formed, (c) a recording film formed uniformly over the surface of this substrate (b), and (d) a protective film formed uniformly over the surface of this recording film (c), and the optical recording process perform the reproduction of the information recorded on the said medium by irradiating the convergent beam of light (f) from the light source, such as a semiconductor laser unit, onto the recording film (c) of this optical recording medium and having the reflected light thereof input into a light-receiving element (not illustrated in the Figure), such as a photodiode. In this regard, the conventional optical recording process is available in two types, namely, the recording and reproducing type of the process, which is not capable of performing the rewriting of the recorded information, and the recording, reproducing and erasing type of the process, which is capable of performing the rewriting of the recorded information, and the known processes of the former type, i.e. the recording and reproducing type, are the "ablative process" and the "bubble process". The "ablative process" is a process whereby a laser beam or the like is irradiated onto the surface of the recording film (c) on the optical recording medium mentioned above, as shown in FIG. 50, so that the recording film (c) in the irradiated area is thereby caused to have a dissolution resulting in the exposure of the surface of the substrate (b). Thus, this process performs the recording and reproduction of information through its utilization of the difference between the reflection factor of the opened area (g) and that of the unopened area. On the other hand, the "bubble process" is a process which irradiates a laser beam, as shown in FIG. 51, and heats some part of the substrate (b), thereby forming bubbles (h) in the irradiated area by using the pressure of the gas generated from the substrate (b). Thus, this process performs the recording and reproduction of information through utilization of the difference between the reflection factor of the area where the bubbles are formed and that of the area where such bubbles are not formed. On the other hand, the process of the latter type, namely, the recording, reproducing and erasing type, which is capable of rewriting the recorded information, is a process which reversibly changes the optical properties of the above-mentioned recording film (c) by such means as light and heat, as shown in FIG. 52, and performs the recording, reproduction, and erasure of information through its utilization of the said changes in the optical properties of the recording film. The known processes realized in concrete form are the "phase changing process" and the "magneto-optical process". In specific terms, the "phase changing process" consists of irradiating a high output laser spot onto a part of the recording film (c) in the crystalline state (cr) as shown in FIG. 53 and thereby transforming the irradiated area from its crystalline state (cr) into its amorphous state (am) through the application of a high speed high temperature heating treatment and a high speed quenching treatment to the irradiated area, and performing the recording and reproduction of information through the utilization of the difference in the reflection factor between the area in the crystalline state (cr) and the area in the amorphous state (am) (See FIG. 54). In the meanwhile, this process performs the erasure of recorded information by irradiating a laser spot beam at a low output onto the recorded area of the recording film (c) mentioned above, as shown in FIG. 55, thus applying a heating treatment at a low temperature and a cooling treatment at a relatively slow pace, thereby transforming the irradiated area from its amorphous state (am) into its crystalline state (cr), i.e. the state of the recording film prior to recording. On the other hand, the "magneto-optical process" irradiates a laser spot beam onto the recording film (c) composed of magnetic material while it is in the state where a magnetic field is applied in the direction indicated by the arrow mark, as shown in FIG. 56, and, using a change in the Kerr rotating angle (Refer to FIG. 57) as effected by changing the said angle by reversing the direction of magnetization in the irradiated area, this process performs the recording and reproduction of information. This process performs the erasure of recorded information by irradiating a laser spot beam to a recorded area of the recording film (c) in the state where the direction of the magnetic field is reversed from that at work at the time of recording, as shown in FIG. 58, thereby putting the direction of magnetization in the irradiated area back to the state of the area prior to recording. However, these existing optical recording processes present such problems as those mentioned below. First, the "ablative process" and the "bubble process" of the recording and reproducing type have the problem that the shapes of the openings and those of the bubbles formed on the recording film, as well as the recording film itself, are susceptible to change over the passage of time, thus lacking stability for the maintenance of recorded information. In addition, it is not possible for the processes to rewrite the recorded information. On the other hand, the "phase changing process" of the recording, reproducing, and erasing type has the problem that it lacks stability for the maintenance of the recorded information, as is the case of the "ablative process" mentioned above, since the amorphous region, which is in a semi-stable state, tends to be crystallized over the passage of time because the crystalline region and the amorphous region, which are different from each other in terms of their energy levels, are present side by side on the recording film after the completion of recording of information thereon by the process which, as described above, performs the recording, reproduction, and erasure of information through its utilization of the changes in optical properties attending the phase change between the crystalline state and the amorphous state. Moreover, the "magneto-optical process" of the recording, reproducing, and erasing type, which is a process for reproducing the recorded information by detection of the Kerr rotating angle as described above, also harbors the problem that it lacks stability for the maintenance of recorded signals because such readily oxidized materials as Tb and Fe contained in the recording film are oxidized along with the passage of time. SUMMARY OF INVENTION In view of the above problems of the prior art, it is an object of this invention to provide an optical recording process which is capable of maintaining recorded information over a long period of time. According to the present invention, an optical recording process provides on a substrate a recording film having such optical properties as are variable by means of light, heat, and so forth and performs the recording and reproduction of information or the recording, reproduction, and erasure of information through its utilization of changes in the optical properties. Thus, the optical recording process is characterized by achieving a selective phase separation of the recording film by such means as light and heat, thereby changing the optical properties in the region of the film. In particular, the recording process of the present invention is characterized by the formation of the above-mentioned recording film with recording material wherein the miscibility gap line appears in the liquid phase region as observed in the phase diagram and also by rewriting the information by means of one beam, which is a single record-erasing beam yielding selectively variable output onto the surface of the recording film mentioned above. Moreover, the recording process of the present invention is characterized by providing a heat interfering layer having heat radiating effect in the area adjacent to the recording film mentioned above and by causing the occurrence of a phase separation attending a spinodal decomposition by applying a high temperature heating treatment and a quenching treatment to the recording film. BRIEF DESCRIPTION OF THE DRAWINGS The manner by which the above objects and other objects, features and advantages of the present invention are attained will be fully evident from the following detailed description when it is considered in light of the accompanying drawings, wherein: FIG. 1 through FIG. 5 illustrate the examples of preferred embodiments of the present invention; FIG. 1 is a schematic sectional view of the optical recording medium used in the first example of preferred embodiments of the present invention; FIG. 2 is a quasi binary phase diagram for the material which constitutes the recording film; FIG. 3 through FIG. 5 respectively illustrate approximate sectional views of the optical recording media used in the second through fourth examples of preferred embodiments of the present invention; FIG. 6 and FIG. 7 illustrate the binodal decomposition and the spinodal decomposition; FIG. 6 is a graph showing the relationship between the free energy difference (ΔG) and the molar fraction (χ) in the binary alloy system composed of A and B. FIG. 7 is a graph showing the binodal decomposition region and the spinodal decomposition region; FIG. 8 is an enlarged chart illustrating the structure of the region where the phase separation has occurred along with the binodal decomposition; FIG. 9 is an enlarged chart illustrating the structure of the region where the phase separation has occurred along with the spinodal decomposition; FIG. 10 through FIG. 48 respectively present the quasi binary phase diagrams for the materials which can be used for the recording film as defined herein for the present invention; FIG. 49 is partial perspective view of the optical recording medium used for the conventional optical recording process; FIG. 50 through FIG. 52 are partial enlarged views of what is shown in FIG. 49; FIG. 53 through FIG. 55 illustrate the principles of recording, reproduction, and erasure by the "phase change process"; and FIG. 56 through FIG. 58 illustrate the principles of recording, reproduction, and erasure by the "magneto-optical process". DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The term, "phase separation", as used hereinabove is a thermodynamically explainable characteristic phenomenon which occurs in common to a group of materials composed of a plurality of constituents, including inorganic and organic compounds, regardless of the differences in their structure, and denotes the phenomenon whereby the initial phase of the materials in the group mentioned above separates into two phases mutually different in composition by the effect of thermal processes suitable for the respective conditions. With regard to the forms of such phase separation, there are two form, one being a binodal decomposition, in which the decomposition is accomplished through a process which can be regarded as a thermodynamically balanced process (which, in specific terms, is a process consisting of heating and gradual cooling), and the other being a spinodal decomposition which is attained through a thermodynamically imbalanced process (which specifically is a process consisting of heating and quenching). In addition, there is a micro phase separation, which occurs typically in such organic compounds as copolymers. Moreover, the phase separation described above is a phenomenon clearly distinguishable from the thermodynamic viewpoint from such phenomena as segregation, peritectogenesis and eutectogenesis as known in the field of metallurgy, and, with reference to the phase diagram, it is a phenomenon which appears typically in such diagrams as those called miscibility gap or solubility gap, which does not include any invariant reaction. The materials which compose the recording film according to the present invention are those materials which have properties subject to the occurrence of a binodal decomposition or a spinodal decomposition by such means as light and heat--for example, such inorganic compounds as alloys, oxides, halogenides, and non-stoichiometric compounds, blends of polymers, which can be regarded as matters composed of two constituents, such organic compounds commonly called "polymer alloys", and those materials which have properties subject to the occurrence of a micro phase separation by such means as light and heat--for example, such random copolymers, alternate copolymers, block copolymers, graft copolymers, stoichiometric high molecular compounds, and so forth. At this point, a detailed description is made of the "binodal decomposition" and the "spinodal decomposition" mentioned above, with reference to the accompanying drawings. First, FIG. 6 presents a graph showing the variation in the difference of free energy (ΔG) to χ in the homogeneous mixture system and the heterogeneous mixture system of a mixture consisting of two constituents, i.e., the constituent A in the ratio of χ molar %! and the constituent B in the ratio of (1-χ) molar %! in their mixture, as observed at the temperature T c and T 1 . In this graph, the curve for ΔG-χ at the temperature T c indicates that the A-B system will be more stable when it is present as a homogeneous mixture in the entire region of composition, and the ΔG-χ curve at the temperature T 1 indicates that the system, in terms of the composition of a and b, will be more stable when it is present in the form of a heterogeneous mixture composed of a and b. Moreover, the curve (A) shown in solid line in FIG. 7 indicates the locus as plotted for the temperature at the point a and the point b on the curve ΔG-χ described above. On the other hand, the curve (B) shown in broken line indicates the locus as plotted for inflection points c and d on the curve ΔG-χ curve given above and demonstrates that the temperature-composition region enclosed by the curve (A) given above is the miscibility region. Then, the temperature-composition region enclosed by the curve (A) and the curve (B), which are miscibility gap lines, in FIG. 7 is called the binodal region, and the phase separation in this region progresses by the binodal decomposition mechanism. This is tantamount to saying that, within this region, only those fluctuations in composition in excess of a given limit value, among the fluctuations which occur in composition in a single phase, will survive in a steady state and that those surviving fluctuations work as the nuclei for the phase separation, which progresses through the growth of such nuclei. Then, the difference in composition is distinct in the interfacial region between the two phases from the initial stage of the phase separation and, as shown in the enlarged approximation of an electronic microscope photograph in FIG. 8, the nuclei which have attained growth are set in a spherical crystalline structure (or in an amorphous structure in some cases) different in composition from what is found in the original phase and have the Rayleigh scattering in them. Accordingly, there arises a difference in the reflection factor between the region where this phase separation has taken place and the region where the phase separation has not occurred, and it becomes possible to perform the optical recording through utilization of this difference in the reflection factor. On the other hand, the temperature-composition region enclosed by the curve (B) in FIG. 7 is called "spinodal region" and, within this region, the phase separation progresses by the spinodal decomposition mechanism. That is to say, the minute fluctuations which occur initially in the composition in a single phase within this region promote the phase separation, which progresses with the predominance of diffusion. Then, in the initial period of the phase separation, the difference in the composition in the interfacial region of the two phases is continuous, and, as shown in the enlarged approximation of the electronic microscope photograph presented in FIG. 9, the phase separation structure assumes a form with the two phases in maze pattern with each other, giving rise to the Rayleigh scattering in the same way as in the case of the binodal decomposition. Therefore, also in this case, a difference occurs in the reflection factor between the region where the phase separation has taken place and the region where it has not occurred, and it is consequently possible to perform the optical recording process through utilization of this difference in the reflection factor. At this juncture, it is noted that the spinodal decomposition does not accompany any nucleus formation, as compared with the binodal decomposition, and consequently requires proportionately less energy for the decomposition, so that the phase separation progresses at a faster speed than in the case of the binodal decomposition. The present invention makes effective use of this property of the spinodal decomposition, and thus the recording process which utilizes the spinodal decomposition, therefore, offers the advantage that the process is capable of performing the recording operation at a speed faster than the process which uses the phase separation attending the binodal decomposition. Furthermore, it is possible to cause the occurrence of the spinodal decomposition in the region which has already been processed for its phase separation by the binodal decomposition mechanism, and, conversely, it is possible to cause the occurrence of the binodal decomposition in the region where the phase separation has already been elicited by the spinodal decomposition. In specific terms, it is possible to cause the shift of the region processed by either of these processes to the state of phase separation attained in the other process by restoring the recording film which is in either one of the states to the state of a single phase by heating it to a temperature higher than the miscibility gap line and thereafter causing a binodal decomposition in this recording film by giving a gradual cooling treatment to the film or causing a spinodal decomposition in the film by giving a quenching treatment to it. Then, since there emerges a difference in the reflection factor between the region where the binodal decomposition has occurred and that where the spinodal decomposition has taken place, it is possible also to perform optical recording by utilizing this difference in the reflection factor, namely, setting the state of phase separation in one region in correspondence to the recording state and the state of phase separation in the other region in correspondence to the erasing state. Moreover, in this recording process which utilizes the spinodal decomposition and the binodal decomposition, it is possible to give the quenching treatment and the gradual cooling treatment to the recording film by switching the output of the irradiating beam. Therefore, this process offers the advantage that the information can be rewritten by one beam by applying a single recording and erasing beam which can thus be selectively switched over for a change of its output. Furthermore, in addition to the above-mentioned recording process which makes use of the phase separation between the spinodal decomposition and the binodal decomposition, it is possible to perform the rewriting of information by one beam, for example, also in the process which utilizes the difference in the optical properties between the amorphous phase of the recording material and the phase separation attending the binodal decomposition in the film. That is to say, it is possible to cause a shift of one state of phase to the other by causing a phase separation attending the binodal decomposition by giving a gradual cooling treatment to the recording film, or by changing it into its amorphous phase by giving it a quenching treatment, after once restoring the recording film, which is in either one of the states, to its single phase state by heating it to a temperature higher than its miscibility gap line. Consequently, it becomes possible to rewrite the information by one beam, for example, by setting the amorphous phase in correspondence to the recording state and setting the other state of phase separation in correspondence to the erasing state. Furthermore, in case the phase separation is in the course of its progress by the binodal decomposition accompanying the nucleus growth, it sometimes happens that the spinodal decomposition progresses in parallel within this nucleus. In this case, a maze pattern structure is observed within the nucleus, in comparison with the case in which the binodal decomposition occurs independently, and the reflection factor in this region where this phase separation has occurred is different from that found in the case where the binodal decomposition occurs alone. Therefore, it is possible also to record tertiary value signals by using the differences in the reflection factor among the region where the phase separation has not occurred, the region where the binodal decomposition and the spinodal decomposition have occurred, and the region where only the binodal decomposition has occurred. Next, the miscibility gap mentioned above appears in the solid phase region (for example, refer to the phase diagrams or the like given in FIG. 10 through FIG. 14) in some cases and appears in the liquid phase region (for example, refer to the phase diagrams or the like given in FIG. 15 through FIG. 17) in other cases in a mixed body composed of two constituents as expressed by the constituent A and the constituent B. In case either one of these recording materials is applied, it is necessary to set the condition for the irradiation of a laser beam or the like for the performance of recording at a temperature higher than its miscibility gap line. Here, in case of the application of a recording material for which the miscibility gap appears in the liquid phase region, the recording film undergoes dissolution by the irradiation of a laser beam set at the prescribed temperature, and the mixture of the two constituents in the recording film is thereby mixed into a state of a single phase, and the recording film is thereafter cooled to shift again to a new state and to attain a phase separation. Thus, this process offers the advantage that it is capable of rewriting the information by one beam as mentioned above through adjustment of this cooling speed. Moreover, according to the present invention, a process which makes dexterous use of the recording material in which this miscibility gap line appears in the liquid phase region and is characterized by its performance of the rewriting of information with one beam by irradiating a single beam for recording and erasing with its output changed selectively. On the other hand, in case a recording material in which the miscibility gap mentioned above appears in the solid phase region, the recording film remains in the state of its solid phase even under the temperature condition that the temperature in the irradiating conditions of a laser beam or the like is set at a level higher than the miscibility gap line, and consequently the diffusing speed is so low that the recording film will not necessarily form any completely uniform phase, in which case it is not possible to apply the process of rewriting the information with one beam as described above. Therefore, in case any material in which the miscibility gap appears in the solid phase region is applied, it will be made possible to apply the information rewriting process with one beam if the irradiating condition for the laser beam or the like is set at a temperature above the liquid phase region, which is still higher than the solid phase region mentioned above. However, in case the information rewriting process with one beam is not employed, it is of course feasible to set the irradiating condition for the laser or the like mentioned above at a temperature within the solid phase region. Moreover, the materials which cause the binodal decomposition or the spinodal decomposition as described above are alloys and mixtures containing two or more oxides or halogenides out of the oxides and halogenides of the individual elements selected out of the following groups of elements: IA group (Li, Na, K, Rb, Cs, Fr) IIA group (Be, Mg, Ca, Sr, Ba, Ra) IIIA group (Sc, Y) IVA group (Ti, Zr, Hf) VA group (V, Nb, Ta) VIA group (Cr, Mo, W) VIIA group (Mn, Tc, Re) VIIIA group (Fe, Co, Ni, Ru, Rh, Pd, Os, Ir, Pt) IB group (Cu, Ag, Au) IIB group (Zn, Cd, Hg) IIIB group (B, Al, Ga, In, Tl) IVB group (Si, Ge, Sn, Pb) VB group (As, Sb, Bi) VIB group (Se, Te, Po) Lanthanoids (Ce, Pr, Nd, Pm, Sm, bu, Gd, Tb, Dy, Ho, Br, Yb) Actinoids (Ac, Th, Pa) To name specific materials, the following alloys which have been ascertained to cause the binodal decomposition from the binodal curve (A) in the phase diagrams given in FIG. 10 through FIG. 12 and the following alloys which have been ascertained to cause the spinodal decomposition from the spinodal curve (B) in the phase diagram given in FIG. 13 can be listed as such materials: Mixtures of PbTe--GeTe (FIG. 10) Mixtures of Au--Pt (FIG. 11) Mixtures of Au--Ni (FIG. 12) Mixtures of PbS--PbTe (FIG. 13) and Mixtures of GeSe 2 --GeSe (For example, Ge 41 .25 Se 58 .75) Mixtures of As--Ge--Te (For example, As 4 Ge 15 Te 8 ) Also, the following materials, which are oxide-oxide mixtures that have been ascertained to cause the binodal decomposition or the spinodal decomposition in light of the literature cited in the brackets: Mixtures of Li 2 O--SiO 2 (Y. Moriya, D. H. Warrington, and R. W. Douglas, Phys. Chem. Glasses, 8,19, (1967)) Mixtures of Na 2 O--SiO 2 (Y. Moriya, D. H. Warrington, and R. W. Douglas, Phys. Chem. Glasses, 8,19, (1967)) Mixtures of BaO--SiO 2 (T. P. Seward, D. R. Uhlmaznn, and D. Turnbull, Phys. Chem. Glasses, 51,278 (1967)) Mixtures of Al 2 O 3 --SiO 2 (J. F. Macdowell and G. H. Beal, J. Am. Ceram. Soc., 52,17 (1969)) Mixtures of B 2 O 3 --SiO 2 (R. J. Charles and F. G. Wagstagg, J. Am. Ceram. Soc., 51,16 (1968)) Mixtures of Li 2 O--B 2 O 3 (R. R. Shaw and D. R. Uhlmann, J. Am. Ceram. Soc., 51,377 (1968)) Mixtures of Na 2 O--B 2 O 3 (R. R. Shaw and D. R. Uhlmann, J. Am. Ceram. Soc., 51,377 (1968)) Mixtures of K 2 O--B 2 O 3 (R. R. Shaw and D. R. Uhlmann, J. Am. Ceram. Soc., 51,377 (1968)) Mixtures of Rb 2 O--B 2 O 3 (R. R. Shaw and D. R. Uhlmann, J. Am. Ceram. Soc., 51,377 (1968)) Mixtures of Cs 2 O--B 2 O 3 (R. R. Shaw and D. R. Uhlmann, J. Am. Ceram. Soc., 51,377 (1968)) Mixtures of PbO--B 2 O 3 (J. H. Simons, J. Am. Ceram. Soc., 56,286 (1973)) Also, the following materials which are mixtures of oxide-oxide and ascertained to cause the phase separation from the miscibility gap line (A) in the phase diagrams given in FIG. 14 through FIG. 30 can be listed as such materials: Mixtures of ZrO 2 --ThO 2 (FIG. 14) Mixtures of CaO--SiO 2 (FIG. 15) Mixtures of B 2 O 3 --PbO (FIG. 16) Mixtures of B 2 O 3 --V 2 O 3 (FIG. 17) Mixtures of SnO 2 --TiO 2 (FIG. 18) Mixtures of NiO--CoO (FIG. 19) Mixtures of Al 2 O 3 --Cr 2 O 3 (FIG. 20) Mixtures of SiO 2 --Al 2 O 3 (FIG. 21) Mixtures of ZnWO 4 --MnWO 4 (FIG. 22) Mixtures of CaWO 4 --NaSm(WO 4 ) 2 (FIG. 23) Mixtures of CaWO 4 --Sm 2 (WO 4 ) 3 (FIG. 24) Mixtures of MnMoO 4 --ZnMoO 4 (FIG. 25) Mixtures of Fe 2 TiO 4 --Fe 3 O 4 (FIG. 26) Mixtures of Ca 3 Cr 2 Si 3 O 12 --Ca 3 Fe 2 Si 3 O 12 (FIG. 27) Mixtures of 65MgSiO 3 /35FeSiO 3 --CaSiO 3 (FIG. 28) Mixtures of LiAl 5 O 8 --LiFe 5 O 8 (FIG. 29) Mixtures of NaAlSi 3 O 8 --KAlSi 3 O 8 (FIG. 30) In addition to these group of materials, the following mixture is to be listed: Mixtures of Na 2 O--B 2 O 3 --SiO 2 In addition, the following materials containing halogenide-halogenide mixtures which have been ascertained to cause the phase separation from the miscibility gap line (A) given in the phase diagrams presented in FIG. 31 through FIG. 45 can be listed as such materials: Mixtures of LiCl--NaCl (FIG. 31) Mixtures of KCl--NaCl (FIG. 32) Mixtures of CsCl--TlCl (FIG. 33) Mixtures of CaCl 2 --MnCl 3 (FIG. 34) Mixtures of CaCl 2 --SrCl 2 (FIG. 35) Mixtures of LiBr--AgBr (FIG. 36) Mixtures of AgBr--NaBr (FIG. 37) Mixtures of KBr--NaBr (FIG. 38) Mixtures of TlBr--CsBr (FIG. 39) Mixtures of KI--NaI (FIG. 40) Mixtures of NaI--CaI 2 (FIG. 41) Mixtures of (GaI 2 ) 2 --NaGaI 4 (FIG. 42) Mixtures of (GaI 2 ) 2 --KGaI 4 (FIG. 43) Mixtures of (GaI 2 ) 2 --RbGaI 4 (FIG. 44) Mixtures of GaAlI 4 --Ga 2 I 4 (FIG. 45) Also, as materials causing the binodal decomposition or the spinodal decomposition mentioned above, it is possible to list the non-stoichiometric compounds of oxides, halogenides, and so forth. Here, the term "non-stoichiometric compounds" means those compounds which are composed of the element M and the element X and yet have their composition deviating from the standard ratios, and, in the case of those non-stoichiometric compounds in which the element M and the element X are compounded in the ratio of (m-δ) versus n (wherein, m and n express positive integral numbers while δ expresses a number which satisfies the relation, 0<δ<1), δ represents th extent of the deviation from the standard ratios of composition and is accordingly called the "non-stoichiometric ratios". Such a deviation from the standard ratios of composition occurs in consequence of a lattice defect present in either the element M or the element X. In case the lattice defect is in the form of a void lattice, for example, in the element, attraction works between void lattices, and this is one factor accountable for the fact that such a non-stoichiometric compound assumes properties different from those of the regular stoichiometric compound. Then, in such a non-stoichiometric compound, the element M and the element X, which constitute the compound, can be regarded as forming a mixture consisting of the two constituents, and such compounds cause the binodal decomposition or the spinodal decomposition in the same way as the recording materials mentioned above. That is to say, such non-stoichiometric compounds cause the occurrence of the binodal decomposition or the spinodal decomposition by the effect of a change in temperature and undergo their phase separation between the phase with more void lattice points and the phase with less of such lattice points (that is to say, between two phases with differences in their non-stoichiometric ratios). To form such non-stoichiometric compounds, it is possible to apply any compound formed of at least one of the metal elements as selected out of the following list: Beryllium (Be), Boron (B), Magnesium (Mg), Aluminium (Al), Silicon (Si), Scandium (Sc), Titanium (Ti), Vanadium (V), Chromium (Cr), Manganese (Mn), Iron (Fe), Cobalt (Co), Nickel (Ni), Copper (Cu), Zinc (Zn), Gallium (Ga), Germanium (Ge), Arsenic (As), Selenium (Se), Rubidium (Rb), Yttrium (Y), Zirconium (Zr), Niobium (Nb), Molybdenum (Mo), Technetium (Tc), Ruthenium (Ru), Rhodium (Rh), Palladium (Pd), Silver (Ag), Cadmium (Cd), Indium (In), Tin (Sn), Antimony (Sb), Tellurium (Te), Hafnium (Hf), Tantalum (Ta), Tungsten (W), Rhenium (Re), Osmium (Os), Iridium (Ir), Platinum (Pt), Gold (Au), Thallium (Tl), Lead (Pb), Bismuth (Bi), Cerium (Ce), Praseodymium (Pr), Neodymium (Nd), Promethium (Pm), Samarium (Sm), Europium (Eu), Gadolinium (Gd), Terbium (Tb), Dysprosium (Dy), Holmium (Ho), Erbium (Er), Thulium (Tm), Ytterbium (Yb), Lutetium (Lu), and Uranium (U) and at least one element selected out of the following: Oxygen (O), Sulfur (S), Nitrogen (N), Hydrogen (H), Iodine (I), Bromine (Br), and Chlorine (Cl). Moreover, such inorganic materials which show a monotonous curve with a convex upward contour in relation to temperature as observed in the phase diagram usually have the miscibility gap mentioned above and can be applied as recording material for the present invention. Then, as specific examples of the non-stoichiometric compounds and inorganic materials mentioned above, it is possible to list such recording material groups as the following material groups which have been ascertained to cause the phase separation in light of the miscibility gap line (A) in the phase diagrams presented in FIG. 46 through FIG. 48: CeO h group (FIG. 46) Mixtures of Bi--Bi 2 O 3 (FIG. 47) Mixtures of CaCO 3 --MnCO 3 (FIG. 48) Moreover, as organic materials applicable as the recording materials mentioned above, there are polymer blends called "polymer alloys", which cause the occurrence of the binodal decomposition or the spinodal decomposition, and random copolymers, alternate copolymers, block copolymers, graft copolymers, and stoichiometric high molecular compounds, which cause a micro phase separation. The following is a description of a case in which an inorganic recording material is applied. The inorganic material mentioned above which causes the binodal decomposition or the spinodal decomposition is coated in the form of a film on the substrate and this film is conditioned to assume a single crystalline state or amorphous state, and this conditioned recording film is then irradiated with a beam of light or heat to achieve a phase separation thereof, and, with a change made in the reflection factor in this region, information is written to the film, so that the film is available for use as an optical recording medium for use exclusively for recording and reproduction, or, with a beam of light or heat being irradiated on the region where the phase separation is thus achieved, the irradiated region is caused to undergo dissolution, and, by restoring this dissolved region to its initial state, the film is available for use as an optical recording medium for use in recording, reproduction, and erasure. Moreover, in case an inorganic recording material which has a miscibility gap appearing in its liquid phase region is applied, or in case an inorganic recording material which has a miscibility gap appearing in its solid phase region is used and yet the irradiating condition of the laser beam or the like is set at a temperature above the level of its liquid phase region, it is possible to apply the information rewriting system with one beam as described above. On the other hand, in the case in which an organic recording material is applied, which is described below, the organic material which causes the binodal decomposition or the spinodal decomposition or a micro phase separation is coated in the form of a film on the substrate and conditioned to the state of a single phase, and, with a beam of light or heat irradiated on the recording film as so conditioned, the film is caused to have selective phase separation, and, with information written to the film through utilization of the changes in the reflection factor in this irradiated region, the recorded film thus processed is offered for use as an optical recording medium exclusively in recording and reproduction, or, with the beam of light or heat or the like being irradiated on this region where the phase separation has thus been produced, the irradiated region of the film is caused to undergo its dissolution, thereby being restored to its initial state, and the film so prepared is offered for use as an optical recording medium for recording, reproduction, and erasure. At this juncture, the materials for the substrate which is used for the formation of the recording film mentioned above are glass and such light-transmissive resin materials as acrylic resin, polycarbonate, and epoxy resin for the type of process in which a beam of light is irradiated from the substrate side. On the other hand, such metal materials as aluminium can be used in the type of process in which a beam of light is irradiated from the side opposite to the substrate. Moreover, in case resin material is used for the substrate, it is feasible to set up a heat interfering layer composed, for example, of SiO 2 , ZrO 3 , and ZnS between the substrate and the recording film in order to thereby prevent the thermal damages of the substrate. If a heat interfering layer made of SiO 3 or the like and having heat radiating effect is installed in a position adjacent to the recording film, it is possible to give high temperature heating and quenching treatments to the recording film and consequently it is made possible to apply the present invention which utilizes the phase separation attending the spinodal decomposition as the means of recording the information. Furthermore, a protective film layer composed of the material forming the above-mentioned heat interfering layer or any such materials as resin hardened by the ultraviolet rays, acrylic resin, polycarbonate, and epoxy resin may be coated over the recording film for the purpose of protecting its surface. In addition, a highly refractive layer made of ZnS or the like may be formed on the surface of the recording film for the purpose of increasing the quantity of light to be reflected from the recording film mentioned above. Next, with regard to the means of coating on the substrate the recording film composed of inorganic material having such properties as cause the binodal decomposition or the spinodal decomposition, it is possible to apply such processes as the thermal vaporization process, the ion plating process, the reactive sputtering process, the chemical vapor phase deposition process (CVD), the ion-aided deposition process (IAD), and the molecular beam epitaxial process (MBE). On the other hand, with regard to the means of coating an the substrate the recording film composed of organic material having such properties as cause the occurrence of the binodal decomposition, the spinodal decomposition, or the micro phase separation, it is feasible to form the film by having the copolymers or the like perform their polymerizing reaction directly on the substrate or to dissolve such copolymers into their secondary compound and to coat the compound on the substrate by some appropriate means. In this regard, the technical means of accomplishing this is applied to the recording, reproducing, and erasing type of the recording film since it is capable of rewriting the recorded information. Yet, in view of the favorable stability in the maintenance of the recorded information, the means according to the present invention can, of course, be applied also to the recording and reproducing type of the recording film, as described above. According to the present invention, the recording film is caused to undergo the phase separation by such means as light and heat, so that the optical properties in the processed region are changed. Therefore, the recording film is not susceptible to changes in the recording film with the passage of time, and it is consequently capable of maintaining the state of its phase separation over a long period of time. Further, according to the present invention, the recording film is formed of such recording material as has a miscibility gap line appearing in its liquid phase region as observed in the phase diagram and the recording film also performs the rewriting of information with a single recording-erasing beam with selectively changeable output, which is irradiated on the surface of the above-mentioned recording film, so that the present invention attains simplification in the rewriting operation. Furthermore, according to the present invention, a heat interfering film has a heat radiating effect and is positioned in the region adjacent to the recording film and causes the recording film to have its phase separation attending the spinodal decomposition by the high temperature heating and quenching treatments applied to the recording film. Therefore, the present invention achieves a reduction of the time required for the phase separation. The present invention has the advantage of the maintenance of the state of phase separation in the recording films of the present invention over a long period of time as discussed below. Specifically, if the region of the recording film where the phase separation has occurred is to resume its original state, it is necessary for the considerably large number of atoms to attain their diffusion over a considerable distance. However, for the recording film which is in the state of its solid phase at least under the room temperature, the speed of diffusion of the atoms of which this recording film is composed is extremely low and their diffusion does not occur in their groups. It is primarily conceivable that these factors are accountable for the point that the recording film mentioned above is less susceptible to change over time. Also, in light of the fact that secular changes occur in the phase change type recording material by the effect of minute fluctuations in the arrangement among the adjacent atoms in it, it is possible to infer that the recording film according to the present invention is not liable to changes over the passage of time. Referring to the drawings, preferred embodiments of the present invention will now be described with reference to the accompanying drawings. FIRST EXAMPLE Now, the optical recording medium used in this first example of preferred embodiments has its principal parts constructed, as shown in FIG. 1, with a heat-resistant plastic (polycarbonate) substrate (1) with a thickness of 1.2 mm and a diameter of 51/4 inches (ISO standard), a heat interfering layer (2) made of SiO 2 in the thickness of 1000 Å and coated on the surface of the substrate (1), and a recording film (3) made of a mixture of LiO 2 and SiO 2 formed on the surface of this heat interfering layer (2). In this regard, the recording film (3) is coated on the heat interfering layer (2) on the substrate (1) by depositing a mixture of (LiO 2 ) 25 and (SiO 2 ) 75 thereon by applying the sputtering process using two targets LiO 2 and SiO 2 and by conditioning the formed film to the crystalline state in a single phase. Then, the optical recording medium is rotated at 1,800 rpm, and, while the medium is kept in this state, a laser beam with an output of 10 mW and a frequency of 3.7 MHz is irradiated onto the recording region of the recording film (3), and, with the temperature in the irradiated region of the recording film (3) being set at the temperature for the miscibility region as shown in the phase diagram given in FIG. 2, the binodal decomposition is caused to occur in the partial region of the recording film, so that the film undergoes its selective phase separation in the region, and information is written to the region by the effect of the changes in the reflection factor in the region. For reproduction, the optical recording medium mentioned above is rotated at 1,800 rpm, and, in this state, a laser beam with the output of 1 mW is irradiated onto the recording film (3), and the reflected beam thereof is read by the light receiving element, and the reproduction of the information is thereby performed. The C/N ratio of the reproduced signal was 50 dB. Moreover, this optical recording medium has been applied as a recording medium for its use exclusively in recording and reproduction. SECOND EXAMPLE The optical recording process as described in this example of preferred embodiments is approximately the same as in the optical recording process shown in the first example of the preferred embodiments, except that this process uses an optical recording medium which is provided additionally with a layer (4) with a high index of refraction, being made of ZnS, a material with a high index of refraction, over the recording film (3) mentioned above. Therefore, this example not only has the same advantages as those of the first example of preferred embodiments, but also offer the additional advantage that it achieves an improvement on the C/N ratio of the reproduced signals to 53 dB (whereas the C/N ratio is 50 dB in the first example) because it can secure an increased quantity of light from the recording film (3) owing to the effect of the layer (4) with a high index of refraction mentioned above. THIRD EXAMPLES The optical recording process described in this example of preferred embodiments is approximately the same as the process described in the first example, except that the recording film (3) of the optical recording medium (Refer to FIG. 4) used in this process is composed of TeO x , which is a non-stoichiometric compound, and that this recording film (3) is formed directly on the substrate (1). Here, the recording film (3) mentioned above is prepared by coating TeO x on the substrate (1) by the RF ion plating process using a Te target in the state in the atmosphere of oxygen gas and by conditioning the film to assume a crystalline state in a single phase. In this regard, the mark x as used in TeO x given above has the value, x=1.75. Moreover, the conditions for setting the RF ion plating process are as follows: ______________________________________Target vaporizing process: Resistance heating Electron beam vaporizationAtmosphere:Ar pressure 1 × 10.sup.-2 to 1 PaO.sub.2 pressure 1 × 10.sup.-2 to 1 PaRF power: 100 to 1,000 KWRate: 0.5 to 10A/sec.______________________________________ Moreover, for the operation for writing information to the optical recording medium mentioned above, the optical recording medium is rotated at 1,800 rpm, and, in this state, a laser beam with an output of 6 mW at the frequency of 3.7 MHz is irradiated onto the recording region of the recording film (3), and, after the recording film (3) in the irradiated region is once dissolved, it is cooled down to cause the binodal decomposition, so that the processed region of the film has a selective phase separation, and the writing of information to the recording medium is thus performed. On the other hand, this process performs the reproduction of the recorded information by rotating the above-mentioned optical recording medium at 1,800 rpm and irradiating, while the medium is kept in this state, a laser beam with an output of 1 mw onto the recording film (3) of the medium and reading the reflected light of the beam by means of the light receiving element. The C/N ratio of the reproduced signal is 55 dB. The fact that the recording film (3) formed of TeO x has the phase separation occurring in it has been ascertained on the basis of the observation that the structure in the irradiated region as viewed in a TEM photograph (a photograph taken under a transmissive type electronic microscope) exhibits a structure peculiar to the binodal decomposition. As a result, the optical recording process as described in this example of preferred embodiments has an excellent advantage in stability for the maintenance of the recorded information, and, above all, it attains a C/N ratio in the reproduced signals at the level of 55 dB, as mentioned above. Thus, the process in this example has proved to be superior to the process described in the second example of preferred embodiments (The process in the second example recorded a C/N ratio at 53 dB). Moreover, this optical recording medium is applied exclusively for recording and reproduction. FOURTH EXAMPLE The optical recording process described in this example of preferred embodiments is almost the same as the recording process described in the third example of preferred embodiments, except for the point that this process is provided with a heat interfering layer (2) made of SiO 2 on its substrate, as shown in FIG. 5, and that it uses an optical recording medium with a recording film (3) made of TeO x coated on the surface of this heat interfering layer (2). Thus, the optical recording medium of which the recording film (3) mentioned above is conditioned to assume a crystalline state in a single phase is rotated at 1,800 rpm, and, while the recording film is kept in this state, a laser beam with an output of 10 mW and a frequency of 3.7 MHz is irradiated onto the recording region of the recording film (3), so that the recording film (3) in the irradiated region is once dissolved and thereafter cooled to cause a selective phase separation therein, and information is thus written to the recording film. This optical recording medium is applied exclusively in recording and reproduction in the same way as in the third example of preferred embodiments. In this example, the output from the beam in the writing process is as high as 10 mW for the operation in which information is written by the irradiation of the laser beam onto the surface of the recording film (3) of the optical recording medium mentioned above, and, unlike the optical recording medium described in the third example, the medium in this example is provided with a heat interfering layer (2). By the heat radiating effect of this heat interfering layer (2), the temperature in the recording film in the irradiated region is cooled more sharply than in the case of the third example of preferred embodiments. Consequently, rather than the binodal decomposition, the spinodal decomposition occurs in the irradiated region of the recording film in this example. Therefore, in contrast with the optical recording process in the third example, which is performed through utilization of the feature that the reflection factor in the region where the binodal decomposition has occurred becomes lower than in the other region, the optical recording process in this example is performed through utilization of the feature that the reflection factor in the region where the spinodal decomposition has occurred will be higher than in the other region. The optical recording process described in this example of preferred embodiments also offers the advantage that it has excellent stability for the maintenance of recorded information as is the case with the processes in the other examples, and, in addition, this process has recorded 50 dB in the C/N ratio of the reproduced signal, thus marking a value higher than that achieved in the existing process. Furthermore, the optical recording process described in this example performs the recording of information through utilization of the phase separation attending the spinodal decomposition and consequently offers the additional advantage that it can operate at a higher writing speed than in the process described in the third example. FIFTH EXAMPLE The optical recording process described in this example is almost the same as the process in the fourth example, except that this process applies the optical recording medium described in the fourth example and that this process performs the rewriting of information with one beam through its utilization of the phase separation between the spinodal decomposition and the binodal decomposition in the recording film (3). In this case, the phase separation attending the spinodal decomposition is set in correspondence with the recording state while the phase separation attending the binodal decomposition is set in correspondence with the erasing state. That is to say, the optical recording medium in which the recording film (3) is conditioned to assume a crystalline state in a single phase is rotated at 1,800 rpm, and, while the medium is held in this state, a laser beam with an output of 8 mw and a frequency of 3.7 MHz is irradiated uniformly over the surface of the recording film (3) mentioned above and the recording film (3) is thereby dissolved once. Then, the recording film (3) is gradually cooled, by which a phase separation attending the binodal decomposition is elicited uniformly in the recording film (3), and its initialization is thereby effected. Next, with the initialized optical recording medium being rotated at 1,800 rpm, and, while the medium is kept in this state, a laser beam an the output of 10 mW and a frequency of 3.7 MHz is irradiated onto the recording region on the recording film (3) mentioned above, and the recording film (3) in the irradiated region is thereby dissolved once and thereafter cooled sharply, by which the said recording film is caused to have a phase separation attending the spinodal decomposition, and the writing of information is performed in this state of the film. For reproduction, the optical recording medium to which information has been thus written is rotated at 1,800 rpm, and, while the said medium is kept in this state, a laser beam with an output of 1 mW is irradiated onto the recording film (3) of the medium and also the reflected beam is read by the light receiving element, the reproduction of the recorded signal being thereby performed. Moreover, the C/N ratio of the reproduced signal is almost the same as that recorded in the fourth example of preferred embodiments. Moreover, for the rewriting of the information written to the optical recording medium mentioned above, this optical recording medium is rotated at 1,800 rpm, and, while the medium is kept in this state, a single recording-erasing laser beam (with an output of 10 mW for recording, an output of 8 mW for erasing, and a frequency of 3.7 MHz) which can be selectively switched for different output levels is irradiated onto the said recording film, by which the rewriting of the recorded information is performed. The optical recording process described in this example of preferred embodiments also has excellent stability for the maintenance of the recorded signal in the same way as in the processes in the other examples of preferred embodiments, and this process exhibits a high C/N ratio of the reproduced signal as compared with the value attained by the existing process. Furthermore, the optical recording process described in this example of preferred embodiments performs the writing and rewriting of information by one beam using the phase separation between the spinodal decomposition and the binodal decomposition, and this process therefore offers the advantage that it is capable of rewriting the recorded information and that it can perform this with simpler operation as compared with the case of the processes described in the other examples. SIXTH EXAMPLE The optical recording process described in this example of preferred embodiments is almost the same as the process in the first example of preferred embodiments, except that the recording film for the optical recording medium used in this process is composed of tri-block copolymer coated directly on the substrate and causes the occurrence of the micro phase separation. Here, the recording film mentioned above is formed directly into a film by the living copolymerizing process of a tri-block copolymer in the structure, (polystyrene)--(polyisoprene)--(polystyrene), and is conditioned to be in the single phase state. Here, instead of this film-forming process, it is also feasible to form a recording film set in the state of a single phase by once dissolving the tri-block copolymer mentioned above into such a solvent as alcohol and applying the solution by spin coating to the surface of the substrate and thereafter forming a recording film set in the state of a single phase by evaporating the above-mentioned solvent, such as alcohol. Then, the operation for the writing of information to the optical recording medium mentioned above is performed by rotating the optical recording medium at 1,800 rpm and, while keeping the medium in this state, irradiating the recording region of the recording film with a laser beam with an output of 7 mW and a frequency of 3.7 MHz, and once dissolving the recording film in the irradiated region and thereafter cooling the film, thereby selectively causing a micro phase separation to occur in the film. The reproduction of the recorded information is performed by rotating the optical recording medium mentioned above at 1,800 rpm and irradiating a laser beam with an output of 0.8 mW to the recording film (3) of the recording medium, while the recording medium is kept in this state, and causing the light receiving element to read the reflected light of this beam. This optical recording medium has been applied as a recording medium exclusively in the recording and reproduction of information. This optical recording process described in this example of preferred embodiments also has the advantage that it is excellent in the stability for the maintenance of the recorded information, and this process has also proved to produce a favorable C/N ratio of the reproduced signal. SEVENTH EXAMPLES The optical recording process described in this example is almost the same as the process described in the fifth example, except that the optical recording medium used in this process is composed of a blend of the following polymers which are placed to form a coat of film on the substrate and cause the spinodal decomposition and the binodal decomposition, depending on the cooling condition applied to them. In this case, moreover, the phase separation attending the binodal decomposition is set in correspondence with the recording state while the phase separation attending the spinodal decomposition is set in correspondence with the erasing state. At this juncture, the recording film mentioned above has been formed into a film by coating the polymer blend of (polystyrene)--(polyisoprene) dissolved in acetone on the substrate and conditioning the film to assume the state of a single phase. The recording film (3) as adjusted to the state of a single phase is rotated at 1,800 rpm, and a laser beam with an output of 8 mW and a frequency of 3.7 MHz is irradiated uniformly over the surface of the recording film (3) mentioned above, the recording film being thereby once dissolved, and thereafter the film is quenched and thereby caused to undergo a uniform phase separation attending the spinodal decomposition, and the initialization of the recording film (3) is thus effected. Next, the initialized optical recording medium is rotated at 1,800 rpm, and, while the medium is kept in this state, a laser beam with an output of 6 mW and a frequency of 3.7 MHz is irradiated onto the recording region of the recording film (3) mentioned above, thereby once dissolving the recording film (3) in the irradiated region. Thereafter, the region is gradually cooled, which causes a phase separation attending the binodal decomposition, and the writing of information is thus performed. For reproduction, the optical recording medium containing the information written to it is rotated at 1,800 rpm, and, with the medium kept in this state, a laser beam with an output of 0.8 mW is irradiated on the recording film (3) of the medium and the reflected beam is read with the light receiving element, and the reproduction of the recorded information is thus performed. In case the information written to the optical recording medium mentioned above is to be rewritten, the optical recording medium is rotated at 1,800 rpm, and, while this recording medium is kept in this state, the rewriting of the recorded information is performed by irradiating a single erasing beam (with an output of 6 mW for recording, an output of 8 mW for erasing, and a frequency of 3.7 MHz), which can be switched selectively for generating variable output, onto the recording film of the recording medium. This optical recording process described in this example of preferred embodiments also has the advantage that it has excellent stability for the maintenance of the recorded information, in the same way as in the case of the other examples of preferred embodiments, and this process also attains a high C/N ratio of the reproduced signal in comparison with the value recorded by the existing process. Furthermore, the optical recording process described in this example of preferred embodiments performs the writing and rewriting of information through utilization of the phase separation between the spinodal decomposition and the binodal decomposition in the same manner as in the fifth example of preferred embodiments, and this process, therefore, offers the advantage that it is capable of performing the rewriting of the information and also offers simplicity and convenience in its operation, as compared with the processes described in the other examples of preferred embodiments. According to the present invention, the recording film undergoes its selective phase separation by applying such means as light and heat, thereby producing changes in the optical properties of the processed region. Therefore, the recording film mentioned above is not susceptible to the occurrence of changes in its state over the passage of time, so that it becomes possible to maintain the state of the phase separation over a long period of time and, consequently, the recorded information for a long time. Further, according to the present invention, a recording film of material having its miscibility gap line appearing in its liquid phase region as seen in the phase diagram enables the performance of the rewriting of the recorded information with one beam by irradiating a single record-erasing beam having an output which can be changed selectively. Therefore, this process offers the advantage that the rewriting operation is thereby simplified. Furthermore, the present invention provides a heat interfering layer having a heat radiating effect in a position adjacent to the recording film and causes the recording film to undergo its phase separation attending its spinodal decomposition by applying high temperature heating and quenching treatments to the recording film. Thus, this process achieves a reduction in the duration of time required for the phase separation and can therefore accomplish the advantageous effect that it improves the rewriting speed.

4y

CROSS-REFERENCE TO RELATED APPLICATION [0001] The subject matter of this application is related to the subject matter of U.S. patent application Ser. No. ______ entitled “MESSAGE-BASED SCALABLE DATA TRANSPORT PROTOCOL”, filed of even date with this application, having the same inventor as this application, assigned or under obligation of assignment to the same entity as this application, and which application is incorporated by reference herein. STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT [0002] Not applicable. FIELD OF THE INVENTION [0003] The invention relates to the field of information technology, and more particularly to a platform configured to initiate and process large-scale network and other data backups or transfers via efficient message-based sessions. BACKGROUND OF THE INVENTION [0004] The increased demand for data enterprise and other storage solutions has fueled corresponding demand in data backup and management tools. Companies, government and scientific organizations and others may require the reliable backup of gigabytes or terabytes of data, or more for archival and other purposes. While physical storage media such as storage area networks, optical storage media, redundant arrays of inexpensive disk (RAID) and other platforms have increased the total archival capacity available to data managers, the ability to efficiently harvest large data backups to host facilities has not always similarly progressed. [0005] For instance, a network administrator may periodically wish to extract the data updates stored to network storage, such as server drives on a local area network (LAN), and transport that data to a secure backup repository at a remote site. However, scheduling and executing that type of large-scale data transport is not always efficient using current technology. For instance, in the case of storing LAN data to a remote site, the administrator may attempt to move that quantity of data using a conventional network protocol, such as the Transfer Control Protocol (TCP). [0006] However, TCP as one transport solution may prove to be a difficult vehicle to communicate the data backup to the remote host, in part because TCP tends to decompose data into comparatively small packets, on the order of a few tens of bytes to a few thousands of bytes. When attempting to drive gigabytes of original or update data to a remote host, that scale will not suffice for efficient transport. Moreover, when performing data flow control on the channel, TCP may pause to seek available bandwidth or capacity on the channel as small as a few thousand bytes, stop and fill that available space in the pipe, and then wait for additional open slots. Again, pushing data on the order of megabytes, gigabytes or more through an intermittent channel at those scales is not efficient when using the granularity of TCP API. Better large-scale and other data backup technologies are desirable. Other problems exist. SUMMARY OF THE INVENTION [0007] The invention overcoming these and other problems in the art relates in one regard to a system and method for message-based scalable data transport, in which one or more individual servers or other nodes communicate data backups and other information to a remote storage host via a communication engine. In embodiments, the communication engine may interface to an underlying transport layer, such as TCP or other protocols, and mediate the data flow from the nodes to the remote store. The communication engine may decompose the data awaiting transport into a set of message objects which are buffered out over connections bundled into established data pipes. The encapsulation of the data into fundamental message objects permits more continuous delivery of the data payload, since the messaging continues as long as the connection is not occupied and is clear, in contrast for instance to pure TCP transport which may exhibit stop-and-go or “chatter” type behavior. In embodiments, one originating session may transmit data over more than one connection, to maximize channel utilization. The communication engine may perform traffic control based on the polling of completion ports to indicate message completion, or other channel mechanisms, but in general not requiring acknowledgment of individual packets or other comparatively smaller data objects. High throughput through the inventive platform and protocol may be achieved. BRIEF DESCRIPTION OF THE DRAWINGS [0008] [0008]FIG. 1 illustrates an illustration of an overall network arrangement for processing data backups or other transfers, according to an embodiment of the invention. [0009] [0009]FIG. 2 illustrates an architecture for message-based data transfer, according to an embodiment of the invention. [0010] [0010]FIG. 3 illustrates a state diagram for message-based data transfer, according to an embodiment of the invention. [0011] [0011]FIG. 4 illustrates a flow diagram of message-based data transfer and associated protocol, according to an embodiment of the invention. DETAILED DESCRIPTION OF EMBODIMENTS [0012] [0012]FIG. 1 illustrates an architecture in which a system and method for message-based scalable data transport may operate, according to an embodiment of the invention. As illustrated in that figure, in embodiments a set of data sources 102 may communicate with each other and with remote resources via network 104 . In embodiments, the set of data sources 102 may include, for instance, individual servers, clients or other nodes or assets having hard disk, magnetic tape, optical or other storage media. Network 104 may in embodiments be or include a local area network (LAN) such as an Ethernet network, a wide area network (WAN), or other network type or topology. Network 104 may in further embodiments be or include a dedicated network for purposes of data backup, a shared network utilized periodically to effect data transport, the Internet, or other networks or facilities. However, in general one or more of the data sources in the set of data sources 102 may have a requirement to backup data in whole or part, on a periodic or other basis and in comparatively large amounts. [0013] As illustrated, when data backups or other data transfers are generated, in embodiments the data transmitted by one or more of the data sources in the set of data sources 102 may be communicated to a storage server 106 , which in turn communicates the data to storage 108 . Storage 108 may in embodiments be or include hard disk resources such as RAID banks, optical media such as rewritable CD-ROMs or DVD-ROMs or others, magnetic tape drives, electronic storage capacity such as random access memory, flash memory or other electronic components, or other storage media. In embodiments, storage 108 may likewise be, include or interface to data storage resources such as storage area networks (SANs) or other assets. In embodiments, storage 108 may be equipped to accept and store relatively large-scale amounts of data backup, for instance megabytes, gigabytes, terabytes or more for enterprise and other purposes. [0014] As illustrated in FIG. 2, according to an embodiments of the invention each of the sources within the set of data sources 102 may communicate with communication engine 110 to initiate, manage and complete a data transport session to data server 106 or other remote or local destination. Communication engine 110 may include or interface to an application programming interface (API) 112 which may expose variables, calls and other interface parameters to the set of data sources 102 to carry out effective data transfer. In the embodiment as shown, each of the data sources in the set of data sources 102 may generate or be associated with a corresponding session within a set of sessions 114 . The set of sessions 104 may contain a queue of input/output buffers 116 , with one or more input/output buffer being allocated to each session. Other arrangements of sessions, queues, buffers and other resources are possible. An example of illustrative code which may in embodiments instantiate a new session from a session object class follows: TABLE 1 CSession Object: typedef enum { CE_SS_SEND_SYNC, // NEED to send sync CE_SS_APP_CONFIRM — // NEED to send ACK ACCEPT_ACK, from app CE_SS_APP_CLOSE — // NEED to send FIN SESSION, CE_SS_ACTION — REQUIRING_STATE, CE_SS_NULL, // null CE_SS_SENDING_SYNC, // Sending SYNC CE_SS_WAITING_ACK, // Waiting for ACK from machine Z CE_SS_WAITING_FOR — // Waiting for ACK ACCEPT_ACK, from app CE_SS_SENDING_APP — // Sending ACK from machine SESSION_ACK, Z to A CE_SS_SESSION_WAITING — // Waiting for WRITE FOR_SYNC_COMPLETE, complete // after WRITE (SYNC) CE_SS_SENDING_FIN, // Sending FIN CE_SS_SESSION_CLOSED, // Session is CLOSED CE_SS_SESSION_READY, // Session is ready } CE_SESSION_STATE; Client Thread: CSession *pSes = new CSession; hr=pSes->Init (L“175.1.1.10”, //IP address of backup LAN or just DNS name 33701, // TCP port L“DLS_SERVER_1”, // principal's name 2*1024*1024, // Output queue length 2 MB 4*1024*1024, // Input queue length 4 MB pSesContext, // points to “GUID_REPLICA” dwSesContextLen ); hr=pCE->CreateSession (pSes); // completes immediately, response on IOCP [0015] Other code, languages or modules or different APIs are possible. [0016] As shown, each of the sessions in the set of sessions 114 may in turn communicate with a dispatcher module in the set of dispatcher modules 118 . The set of dispatcher modules 118 may themselves secure connections to one or more of a set of connections 120 . The set of connections 120 (which may be one or more) may in embodiments use multiple possible underlying communications mechanisms like TCP via Winsock, pipes or others. Each connection in the set of connections 120 aggregated into a logical pipe 122 may communicate with storage server 106 , or other remote or local hosts or resources. In embodiments pipe 122 may be established before establishing the set of connections 120 within that structure, but other setup phases and configurations are possible. In embodiments, the invention may support or employ a large number of connections in one or more pipes, for instance on the order of 1000 simultaneous connections, or more or less depending on implementation. [0017] As illustrated, the storage server 106 may contain a destination input/output queue 124 , to buffer incoming and outgoing message traffic to the storage server 106 or other ultimate destination. More particularly, at fixed, periodic, selected or other times, one or more of the sources in the set of data sources 102 may initiate a data transfer to the storage server 106 via communication engine 110 and associated resources. The data transfer may be or include, for instance, the backup of a server hard disk or other storage, the capture of large-scale scientific or commercial data, or other data transport tasks. Communication engine 110 may decompose the resident data from the one or more sources in the set of sources 102 into a set of message objects, for more efficient queuing and transfer. [0018] As shown, the session illustrated as Session A in the set of sessions 114 may generate two messages, labeled Message 1 and Message 2 , for transfer to storage server 106 . Those and other messages may in embodiments be on the order of many megabytes, or larger or smaller, in size. Likewise illustrated Session B has generated a message labeled Message 3 for transport to storage server 106 . Session C is illustrated as receiving a message labeled Message 4 , on the intake side. [0019] Dispatcher modules in the set of dispatcher modules 118 may bind multiple message streams from the set of input/output buffers 116 to one or more connections in the set of connections 120 and multiplex messages from different sessions into the same pipe of connections. As illustrated, dispatcher module labeled D 1 communicates traffic from Session A including Message 1 and Message 2 to Connection 1 , while dispatcher module D 2 combines the message stream to and from Session B and Session for connection to Connection 2 . Other combinations are possible. As shown, communication engine 110 interacting with the set of sessions 114 and the set of dispatchers 118 and other resources may attempt to drive the greatest possible number of pending messages through the set of connections 120 of pipe 122 , to achieve the greatest possible utilization of available bandwidth to storage server 106 . In embodiments, individual sessions in the set of session 114 may specify different types of network connections, such as ports, sockets or other parameters, for different messages or sets of messages. [0020] Each of the data sources in the set of data sources 102 , as well as individual connections in the set of connections 120 and other links in the transport chain to storage server 106 , may have different available bandwidths or other transmission characteristics. The queue of input/output buffers 116 in conjunction with the other transmission resources permit buffering action to accommodate the slowest link or links in that chain and varying characteristics of traffic both on sender and receiver side, while driving data transport to the greatest possible utilization. The communication engine 110 may for instance continuously or periodically scan the set of connections 120 to determine whether they are occupied with an outgoing or incoming message stream. [0021] In embodiments those probes or scans may be made using the completion port facility available under the Microsoft Windows™ family of operating systems, according to which the GetQueuedCompletionStatus and other commands may return messages indicating the departure of a given message from queue, or not. Since the communication engine 110 , set of dispatchers 118 and other resources may rely upon a message object as the fundamental unit of data transfer, the overall operation of the invention in embodiments may be directed toward fast large-scale transfers, since there is no stop and go effect from the processing of individual pieces of data as in pure TCP transmission modes. Rather, according to the invention a comparatively large-scale message may be generated, entered into queue in the queue of input/output buffers 116 , and released for transmission to storage server 106 or other destination. [0022] In embodiments, each session in the set of sessions 114 or communication engine 110 may wait to replenish the queue until the session itself determines that the transmission of the message object is complete. Since the duty to confirm that status resides on the transmitter side, there is no feedback loop from the receiver end, and that type of overhead cost is avoided. The set of sessions 114 may instead wait for confirmation from the queue of input/output buffers 116 that space in queue has opened, to prepare the next message for transmission. The set of sessions 114 thus may not attempt to refill the queue until whole message units are processed. The set of sessions 114 may incorporate a timeout function, to remove a message from the queue of input/output buffers 116 if the corresponding input/output buffer does not confirm the departure of the message to the set of connections 120 within a fixed amount of time, such as 1 minute. The set of sessions 114 may use other timeout or other checking criteria, such as variable delay times, a fixed or variable number of repeat attempts to be made before retiring a message, or others. [0023] Each of the message objects themselves may be communicated via the connections in the set of connections 120 using TCP itself as a lower level protocol. Other protocols are possible. Because the communication engine 110 and its associated message-based protocols govern flow control at a higher level, TCP datagrams may flow without small-scale flow control, error checking or other processing which would tend to slow down large, scalable transfers of the type managed by embodiments of the invention. [0024] In embodiments, the communication engine 110 , API 112 and other resources may introduce layers of security protection to protect the data transported to the storage server 106 or other destination. For instance, each session in the set of sessions 114 or connection in the set of connections 120 may be authenticated via digital certificates such as Kerberos, X.509 or other objects, secure socket layers or other mechanisms, before being permitted to be aggregated into pipe 122 . Individual messages themselves may likewise be encrypted to deter interception or alteration of the data being moved to storage server 106 . Various security, encryption or other techniques, such as Microsoft™ Security Support Provider Interface (SSPI), public key such as RSA standards, private keys such as Digital Encryption System (DES) mechanisms, or others may be employed to protect message content or other aspects of the transmission process. In embodiments, authentication, encryption and related information may be exposed at the level of API 112 . [0025] [0025]FIG. 3 illustrates a set of state machines 126 representing successive states of communications processing, according to an embodiment of the invention. As illustrated in that figure, the API 112 may present an interface to invoke communications resources to effect message-based data transport, such as server backup, large-scale data taking such as scientific or commercial data capture, or other purposes. Delivery of messages via the set of sessions 114 may in embodiments be reliable, in the sense of individual messages either being transmitted in whole, or queued for retransmission. As shown, multiple sessions may be established to multiple destinations, illustratively Session 1 connecting to Destination 1 , Session 2 connecting to Destination 1 , and Session 3 connecting to Destination 3 . As shown, Session 1 and Session 2 may loop between states 1 and 2 , awaiting completion of transmission of respective messages to Destination 1 or other triggering events. Communication with Destination 1 may be via a Connection 1 state machine for Session 1 , and Connection 2 state machine for Session 2 . Each of Connection 1 and Connection 2 may communicate with associated encryption and authentication state machines, to safeguard against unauthorized viewing or alteration of message objects. Each of Connection 1 and Connection 2 may likewise communicate with a respective Socket I/O State Machine which regulates access to respective Socket 1 and Socket 2 connections to Destination 1 . Session 3 may communicate with similar state machines processing transmission, encryption, authentication and socket connections to Destination 3 . In embodiments, transmission of individual messages may be asynchronous, in that messages may be queued and released according to channel occupancy and other factors, rather than according to timed slots. The creation of individual connections and sessions may likewise in embodiments be asynchronous. Additional state machines and interconnections are possible, and other states are possible for each state machine or process. [0026] Overall data transport processing is illustrated in FIG. 4. In step 402 , one or more sessions in the set of sessions 114 may be generated. In step 404 , a session sync message may be transmitted from a data source in the set of data sources 102 and transmitted to the destination input/output buffer 124 of storage server 106 . In step 406 , a completion message for session sync may be posted to storage server 106 . In step 408 , the storage server 106 may accept the session request. [0027] In step 410 , a session sync acknowledgement message may be transmitted from the destination input/output buffer 124 of storage server 106 to the corresponding input/output buffer in the set of input/output buffers 114 for the requesting data source. In step 412 , a completion message for session acknowledgement may be posted to the originating data source in the set of data sources 102 . In step 414 , the transmitting data source may transmit a first message, denoted Message 1 , to its associated input/output buffer in the set of input/output buffers 114 . In step 416 , the transmitting data source may transmit a second message, denoted Message 2 , to its associated input/output buffer in the set of input/output buffers 114 . In step 418 , the transmitting data source may transmit a third message, denoted Message 3 , to its associated input/output buffer in the set of input/output buffers 114 . In step 420 , the data source may receive an error message indicating that the corresponding input/output buffer is full, so that Message 3 is not accepted into queue. In step 422 , Message 1 may be transmitted to the destination input/output buffer 124 of storage server 106 . In step 424 , a completion message for the transmission of Message 1 may be posted to storage server 106 or other destination. In step 426 , an acknowledgement message acknowledging receipt of Message 1 may be transmitted to the input/output buffer of the data source of that message. In step 428 , a completion message for Message 1 may be transmitted to the corresponding data source. [0028] In step 430 , Message 2 may be transmitted to the destination input/output buffer 120 of storage server 106 or other destination. In step 432 , a completion message for Message 2 may be posted to the storage server 106 . In step 434 , Message 3 may be retransmitted to the input/output buffer corresponding to the data source of that message. In step 436 , an acknowledgment message indicating receipt of Message 2 with a window size (WndSize) of zero units may be transmitted to the input/output buffer of the data source for that message. In step 438 , a completion message for Message 2 may be posted to that source. In step 440 , Message 4 may be transmitted from a data source among the set of data sources 102 to its corresponding input/output buffer among the queue of input/output buffers 116 . [0029] In step 442 , the client application or other resource to receive Message 1 retrieves Message 1 from the destination input/output buffer 124 . In step 444 , an acknowledgement message for Message 2 with a window size (WndSize) of 1 unit may be transmitted to the corresponding input/output buffer of the source of that message. In step 446 , Message 3 may be transmitted to the destination input/output buffer 124 of storage server 106 . In step 448 , processing may terminate, repeat, or return to a prior processing point. [0030] The foregoing description of the invention is illustrative, and modifications in configuration and implementation will occur to persons skilled in the art. For instance, while the invention has in embodiments been described in terms of multiple data sources communicating via one communications link to a remote host, in embodiments one or more nodes or sessions may communicate via separate physical or logical links to a remote data host or other destination. [0031] Similarly, while the invention has in embodiments been described as transporting backup data to a single remote host, in embodiments the data may be delivered to separate logical or physical hosts or media. Other hardware, software or other resources described as singular may in embodiments be distributed, and similarly in embodiments resources described as distributed may be combined. The scope of the invention is accordingly intended to be limited only by the following claims.

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BACKGROUND OF THE INVENTION Field Of The Invention Rechargeable batteries, as for example, lead-acid storage batteries have been used for many years as sources of portable low-voltage electricity. In such batteries, chemical energy is converted directly into electrical energy and a number of cells are connected in series. In this manner, each cell adds its voltage to the total voltage of the voltage cells in the string below it. The output voltage of such cell depends upon the type of cell and material used within the cell. For example, galvanic cells such as the lead-acid storage batteries produce an open circuit voltage of approximately 2.2 volts per cell. The concept of connecting voltage cells in series to produce a useful working voltage is easily accomplished as long as the performance of each voltage cell closely matches the performance of the other cells in the stack. However, if for some reason, a voltage cell does not perform in the same manner as the other cells in the group and presents a higher impedance to the current flowing through it, localized heating may occur within the cell which can cause permanent damage to the cell. In some cases, the cell polarization reverses to produce a potentially dangerous situation. This performance imbalance, localized heating, and reversal of cell polarization readily occur in galvanic cells which are deeply discharged. The aforementioned problems are exacerbated in modern sailing craft which incorporate two banks of batteries for operating automatic furling, lighting and other electrical apparatus. In such craft, it is common practice to use one bank of batteries on odd days of the month and the other bank of batteries on even days. On those days when one bank of batteries is being used, i.e., discharging, the other bank of batteries may be charged when the boat's motor is in use. This results in deep cycling of the batteries and greatly shortens the effective life of the battery. Placing the two batteries banks in a parallel circuit offers a number of advantages. By doing so, one obtains twice the power and capacity which reduces the cycling, heat, plate warpage, and the like. In addition, both battery banks will be charged whenever the engine is used so that each bank of batteries will be maintained at near capacity or a fully charged state. It has now been found that placing the two battery banks in parallel has greatly increased the useful life of the batteries. For example, in one boat, two banks of five year batteries lasted only one year when used alternately. By contrast, two battery banks of two year batteries in a parallel circuit, have lasted under similar conditions for several years with no evidence of deterioration. Nevertheless, there is one serious problem associated with placing the battery banks in a parallel circuit. The problem is that if a single cell fails, it can short out both banks of batteries so that there is a total loss of power. For this reason, it is highly desirable to include an early warning device to indicate any impending battery failure due to the degeneration of one cell. Then, at the first indication of cell degeneration, the battery can be switched out of the circuit and the other battery bank relied upon until such time that the weakened battery can be replaced. BRIEF SUMMARY OF THE INVENTION In essence, the present invention contemplates a battery monitor for detecting cell degeneration in a circuit which includes a pair of rechargeable batteries. The circuit includes a first bank of battery cells which are connected in series and a second bank of battery cells which are also connected in series. First circuit means are provided and connect the first bank of battery cells and the second bank of battery cells in parallel with one another. The second circuit means connects a midpoint between the plurality of cells in the first bank of battery cells and a midpoint between the plurality of cells in the second bank of batteries. This second circuit means also includes means for indicating a voltage change due to the degeneration of a cell when the voltage change exceeds a predetermined value. In the preferred embodiment of the invention, the second circuit includes a Wheatstone bridge. As indicated above, the invention is especially suitable for maritime applications, in which it is desirable to build redundancy into the power supplies by connecting banks of batteries in parallel and providing switches for disconnecting banks requiring servicing. The principle objective of the invention is to provide continuous real time monitoring of the condition of the battery cells using a single measuring device connected at an appropriate location between the cells. It is a further objective of the invention to provide a power supply circuit for such applications, and to provide real time monitoring not only of the changes in overall voltage output, but also an indication of which bank of cells is responsible for the changes in order to permit one of the individual banks to be serviced while the other bank continues to operate. It is yet another objective of the invention to accomplish the above objectives with a minimum of circuit connections. These objectives are accomplished, according to a preferred embodiment of the invention, by connecting the battery cells in two parallel connected banks of mutually series connected cells such that the total internal resistance of cells in good condition is equal on either side of a midpoint in each of the banks, and by connecting a measuring device across the midpoints of the cells to form a bridge circuit, with the measuring device being thereby responsive to changes in internal resistance of cells on either side of the midpoint, and with the polarity of resulting voltage changes between the midpoints determining the bank containing the cells whose internal resistance has changed. The foregoing, as well as other objects and advantages of the invention, will become apparent from the following detailed description when considered in conjunction with the accompanying drawings, wherein like reference characters designate like parts throughout the several views, and wherein: BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a circuit diagram illustrating a first embodiment of the invnetion; FIG. 2 is a circuit diagram illustrating a second embodiment of the invention; and FIG. 3 is a schematic illustration of a preferred embodiment of the invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS As illustrated in FIG. 1, power to the load 2 is normally supplied by two banks of batteries, each of which is made up of a plurality of individual batteries cells mutually connected in series. Typically, each bank includes a pair of batteries 10,20 and 30,40, and each battery is made up of six two volt cells, with the two banks of batteries being connected to the load through respective switches 50 and 60. When switches 50 and 60 are both closed, the two pairs of batteries are connected in parallel, and when either of the switches is open, the associated bank is disconnected from the load, leaving the other bank connected in series with the load. Normally, both switches are closed to provide increased battery life, with the appropriate switch being opened to disconnect the corresponding pair of batteries in order to permit replacement or servicing of an individual battery. It will be appreciated by those skilled in the art that the batteries 10-40 may take a variety of forms, and that the invention is not limited to pairs of 12 Volt batteries made up of individual two volt battery cells. Each bank can be made up of an arbitrary number of batteries, each consisting of an arbitrary numbers of internal battery cells connected in parallel or series. However, irrespective of the battery structure, each of the batteries can be represented as an ideal voltage source and an internal resistance, so that the overall circuit can be represented by the equivalent circuit in which the total internal resistances R10-R40 of the respective batteries are connected as illustrated in FIG. 2 to a voltage source which represents the combined voltage output of the battery banks. In both FIGS. 1 and 2, the series connections between the batteries in each bank are represented by letters A and C, and the common parallel connections by letters B and D. The use of parallel connected banks of batteries is of course conventional. The unique aspect of the circuit shown in FIG. 1, and its equivalent shown in FIG. 2, is that a measuring device 70 is connected between points A and C, as will be described below, for purposes of monitoring the condition of the batteries in the bank. While points A and C could in theory be located at points other than the midpoints of the two banks of batteries, at the physical connections between respective batteries in each pair, for purposes of convenience it is preferred that the total number of cells on each side of connection points A and C be equal, so that resistances R10-R40 in the equivalent circuit of FIG. 2 are equal when the batteries are in good condition. If not equal, then at least the ratio R10/R20 should equal the ratio R30/R40. The objective of the circuit configuration illustrated in FIG. 1 is to provide a convenient way of monitoring the conditions of the batteries in the respective banks and to provide a warning when one or more battery cells in either bank needs to be serviced or replaced. The reason the circuit is able to accomplish this objective is that when a battery cell fails, the internal resistance of the cell increases, at which time a potential difference occurs between points A and C, which can be measured by the measuring device 70 connected between the points. By connecting the measuring device across the midpoints of the banks of batteries, a baseline of zero can be used to indicated normal operation of the batteries, so that the presence of any non-zero potential difference indicates a failing cell. If the ratios of the resistances on either side of the ammeter have been chosen to be equal (i.e., R10*R40=R20*R30) when the batteries are operating properly, so that no current will appear at device 70, when the internal resistance of any cell rises as a result of aging or defect, then the ratios of the resistances will change and a current will be measured, the direction of the current depending on which bank includes the defective battery. The magnitude of changes that can be measured in this way depends solely on the sensitivity of the measuring device 70, and thus it is possible to provide a warning for very small changes in battery condition, if desired. As a result, it can be seen that the measuring device 70 can be any current responsive device, including a micro-ammeter, lighting circuit, sound generator, computer, or combination of the above. In addition, a threshold activating current can be chosen so that the measuring device does not respond to minimal changes in battery function such as might be caused by temperature differences rather than battery cell deterioration, a computer can be used to monitor current fluctuation patterns in order to separate aging patterns from ordinary fluctuations. One of the advantages of the illustrated arrangement is the simplicity of the connection required to monitor battery condition, namely a single connection or bridge between points A and C. Because of this simplicity it might, in hindsight, appear that this is the most obvious way to monitor the condition of a parallel connected bank of batteries. However, this is not the case. In general, the usual way to monitor battery condition is to periodically measure, using a voltage measuring device, the voltage output of individual batteries or the total voltage output of the banks of batteries. What the inventor has recognized is that, in a parallel configuration involving multiple batteries in each bank, the internal resistances of the batteries form what is referred to in the art as a Wheatstone bridge. While Wheatstone bridges are also known, the usual way of applying the Wheatstone bridge concept is to connect a component whose resistance is to be measured as one of the resistors in the bridge, with the other three resistors being in the form of components of known resistance. To conceive of the parallel connected batteries as forming a bridge circuit actually allows simplification of the measuring circuit, and at the same time provides continuous monitoring and the ability to generate a warning without the relatively complex circuitry that would be required using conventional battery monitoring equipment. Furthermore, it will be appreciated that the illustrated configuration not only provides continuous real time monitoring of cell condition, but also that the it provide an indication of which of the banks contains a defective cell. This can easily be accomplished by making measuring device 70 responsive to the polarity of the potential difference between points A and C. This is especially important where one of the banks must remain connected while the other is being serviced, as is the case for a ship at sea. Thus, when the measuring device indicates that one of the banks needs to be service, the corresponding switch 50 or 60 can be opened, either manually or automatically under control of the measuring device, to disconnect the defective bank from the main power supply circuit. Because of the parallel configuration, the remaining bank will still provide sufficient voltage to maintain operation of the load. As is apparent from the above, the invention requires a minimum of four discrete battery cells. However, the upper limit on the number of cells is unlimited. In addition, where the number of batteries is greater than four, additional monitors could be added by forming additional bridge connections, and the sophistication of the monitoring equipment represented by measuring device 70 can be increased as desired. Consequently, it will be appreciated that the invention is not intended to be limited to the specific configuration shown, but rather should include all variations and modifications fairly included within the scope of the appended claims. While the invention has been described in connection with its preferred embodiment, it should be recognized and understood that changes and modifications may be made therein without departing from the scope of the appended claims.

4y

CROSS-REFERENCE TO RELATED APPLICATIONS [0001] This application is a continuation of U.S. application Ser. No. 10/775,442, filed Feb. 10, 2004, now allowed, which is a division of U.S. application Ser. No. 09/990,422, filed Nov. 21, 2001, now U.S. Pat. No. 6,719,784, which are incorporated herein by reference. FIELD OF THE INVENTION [0002] This invention relates to methods of preparing tubular prostheses, and, more particularly, to techniques for forming multi-layered prostheses. BACKGROUND OF THE INVENTION [0003] Formation of prostheses from polytetrafluoroethylene (PTFE), particularly expanded polytetrafluoroethylene (ePTFE) is well known in the prior art. ePTFE includes a node and fibril structure, having longitudinally extending fibrils interconnected by transverse nodes. The nodes are not particularly strong in shear, and, thus, ePTFE structures are susceptible to failure in a direction parallel to the fibril orientation. ePTFE structures (tubes, sheets) are typically paste extruded, and, the fibrils are oriented in the extrusion direction. [0004] Vascular grafts formed of ePTFE are well known in the art. Where sutures have been used to fix such grafts, suture hole elongation and propagation of tear lines from suture holes have been noted. [0005] To overcome the deficiencies of the prior art, techniques have been developed which re-orient the node and fibril structure of an ePTFE element to be transverse to the extrusion direction. By orienting the fibrils at an angle relative to the extrusion direction, the tear strength of a respective product may be greatly improved. In one technique set forth in U.S. Pat. Nos. 5,505,887 and 5,874,032, both to Zdrahala et al., an extrusion machine is described having a counter-rotating die and mandrel arrangement. Accordingly, upon being extruded, a single-layer unitary PTFE tube is formed having an outer surface twisted in one helical direction, and an inner surface twisted in an opposite helical direction. Although tubes formed in accordance with the method of U.S. Pat. Nos. 5,505,887 and 5,874,032 are expandable to form an ePTFE structure, the fibrils of the structure are oriented generally parallel to the expansion direction after expanding as shown in the micrograph of FIG. 5 in U.S. Pat. No. 5,874,032. Also, the tube tends to thin out unevenly under expansion, and, suffers from “necking”. SUMMARY OF THE INVENTION [0006] To overcome the deficiencies of the prior art, a method is provided wherein ePTFE tubes are counter-rotated, coaxially disposed, and fixed one to another to form a composite multi-layer prosthesis. By rotating the tubes, the tubes each becomes helically twisted with its node and fibril configuration being angularly offset throughout from the longitudinal axis of the tube (and, thus, angularly offset from the extrusion direction of the tube). With counter-rotation, the nodes and fibrils of the two tubes are also angularly offset from each other, resulting in a relatively strong composite structure. The composite multi-layer structure is akin to plywood, where alternating layers have differently oriented grain directions. [0007] These and other features will be better understood through a study of the following detailed description and accompanying drawings. BRIEF DESCRIPTION OF DRAWINGS [0008] FIG. 1 is an elevational view of an ePTFE tube; [0009] FIG. 2A is an elevational view of a helically wound tube twisted in a first rotational direction; [0010] FIG. 2B is a schematic of the node and fibril orientation of the first tube in a helically wound state; [0011] FIG. 3A is an elevational view of a helically wound tube twisted in a second rotational direction; [0012] FIG. 3B is a schematic of the node and fibril orientation of the second tube in a helically wound state; [0013] FIG. 4A is an elevational view of a prosthesis formed in accordance with the subject invention; [0014] FIG. 4B is a schematic of the node and fibril orientations of the composite prosthesis; and, [0015] FIG. 5 is an exploded view of a prosthesis having a radially-expandable support member. DETAILED DESCRIPTION OF THE INVENTION [0016] The invention herein provides a multi-layer prosthesis which may be used as a graft to replace a portion of a bodily passageway (e.g., vascular graft), or within a bodily passageway to maintain patency thereof, such as an endovascular stent-graft. In addition, the prosthesis can be used in other bodily applications, such as the esophagus, trachea, colon, biliary tract, urinary tract, prostate, and the brain. [0017] The prosthesis is composed of multiple layers, including coaxially disposed ePTFE tubes. To illustrate the invention, reference will be made to the use of two ePTFE tubes, although any number may be utilized consistent with the principles disclosed herein. With reference to FIG. 1 , an ePTFE tube 10 is shown which extends along a longitudinal axis 12 . The ePTFE tube 10 is preferably formed by extrusion, thus having its fibrils generally parallel to the extrusion direction of the tube, which coincides with the longitudinal axis 12 . The ePTFE tube 10 includes a wall 14 (which is seamless if extruded), that extends about a lumen 16 . The wall 14 includes an inner luminal surface 18 facing the lumen 16 , and an outer, abluminal surface 20 . The ePTFE tube may be formed of any length and of various dimensions, although it is preferred that the dimensions be generally constant throughout the length thereof. In describing first and second tubes of the invention, like reference numerals will be used to describe like elements, but with the extensions “A” and “B” for differentiation. Elements associated with a first tube will have the extension “A”, while elements associated with a second tube will have the extension “B”. [0018] Referring to FIG. 2A , a first ePTFE tube 10 A is shown disposed along a longitudinal axis 12 A. The first tube 10 A is twisted about its longitudinal axis 12 A in a first rotational direction, such as clockwise, as shown in FIG. 2A . The tube 10 A may be twisted over any given range of degrees, although it is preferred that the tube be twisted at least 10 degrees. Accordingly, as represented by the hypothetical reference axis 22 A, the first tube 10 A is helically wound in the first rotational direction. As a result and as shown in FIG. 2B , fibrils 24 A are generally parallel to the reference axis 22 A, with the fibrils 24 A being angularly offset an angle a from the longitudinal axis 12 A, and, thus, being also angularly offset the angle a from the original extrusion direction of the first tube 10 A. Nodes 26 A are generally perpendicular to the fibrils 24 A. With the fibrils 24 A, and the nodes 26 A, being obliquely disposed relative to the longitudinal axis 12 A, failure along the longitudinal axis 12 A may be reduced. [0019] Referring to FIGS. 3A and 3B , a second ePTFE tube 10 B is shown being twisted in a second rotational direction different than the first rotational direction of the first tube 10 A. As shown in FIG. 3A , the second ePTFE tube is twisted in a counterclockwise direction. The particular rotational direction of twisting may be switched for the first and second tubes 10 A and 10 B. As with the first tube 10 A, the amount of twisting of the second tube 10 B maybe varied, although it is preferred that at least a 10 degree displacement be provided. The helically wound distortion of the second tube 10 B is represented by the hypothetical reference axis 22 B. As shown in FIG. 3B , fibrils 24 B are generally parallel to the reference axis 22 B and are angularly offset an angle P from the longitudinal axis 12 B (and, thus, the extrusion direction). Nodes 26 B are generally perpendicular to the fibrils 26 A. The oblique disposition of the fibrils 24 B and the nodes 26 B resists failure along the longitudinal axis 12 B. [0020] FIG. 4A shows a prosthesis 100 including the first tube 10 A, in its twisted helical state being coaxially disposed within, and fixed to, the second tube 10 B, in its twisted helical state. It is preferred that the tubes 10 A and 10 B be generally coextensive, although the ends of the tubes need not be coterminous. Because of the different rotational orientations of the node and fibril structures of the tubes 10 A and 10 B, the node and fibril structures are angularly offset from each other. In particular, as shown schematically in FIG. 4B , because of the coaxial arrangement of the tubes 10 A, 10 B, the longitudinal axes 12 A and 12 B are generally colinear. Also, the fibrils 24 A of the first tube 10 A are angularly offset from the fibrils 24 B of the second tube 10 B by an angle γ. The angular offset of the fibrils 24 A and 24 B provides the prosthesis 100 with resistance against failure not provided by either tube 10 A, 10 B alone. In a preferred embodiment, with the angles α and β being each at least 10 degrees, the angle γ will be at least 20 degrees. Preferably, the node and fibrils of each of the tubes 10 A, 10 B are generally-equally angularly offset throughout the respective tube 10 A, 10 B. [0021] Because the first tube 10 A is disposed within the second tube 10 B, the second tube 10 B is formed dimensionally slightly larger to accommodate the first tube 10 A within its lumen 16 B. [0022] As an alternative, only one of the tubes 10 A, 10 B may be twisted. The node and fibrils of the two tubes 10 A, 10 B would, nevertheless, be angularly offset. [0023] In a preferred manner of preparing the prosthesis 100 , the first tube 10 A is provided and mounted onto a mandrel where it is twisted into its desired helical configuration. The twisted configuration of the first tube 10 A is maintained. The second tube 10 B is provided and twisted as desired, and in its twisted state telescoped over the first tube 10 A. The first and second tubes 10 A and 10 B are fixed together using any technique known to those skilled in the art, preferably sintering. Adhesive may also be used to bond the tubes, such as a thermoplastic fluoropolymer adhesive (e.g., FEP). Once fixed, the prosthesis 100 is prepared. [0024] Although reference has been made herein to extruded ePTFE tubes, tubes formed by other techniques may also be used, such as with rolling a sheet, or wrapping a tape. Generally, with these non-extrusion techniques, the fibrils of the ePTFE will not initially be oriented parallel to the longitudinal axis of the tube, but rather transverse thereto. These non-extruded tubes may replace one or more of the tubes 10 A, 10 B in a non-twisted state or in a twisted state. [0025] As shown in FIG. 5 , the prosthesis 100 may also include a radially expandable support member 28 , which may be disposed interiorly of the first tube 10 A, exteriorly of the second tube 10 B, or interposed between the two tubes 10 A, 10 B. Additionally, multiple support members located at the aforementioned locations may be provided. The radially expandable support member 28 may be fixed to the tubes 10 A, 10 B using any technique known to those skilled in the art, such as bonding. Additionally, with the radially expandable support member 28 being interposed between the tubes 10 A, 10 B, the tubes 10 A, 10 B may be fixed together through any interstices formed in the radially expandable support member 28 . [0026] The radially expandable support member 28 may be of any construction known in the prior art which can maintain patency of the prosthesis 100 . For example, as shown in FIG. 5 , the radially-expandable support member 28 may be a stent. The particular stent 28 shown in FIG. 5 is fully described in commonly assigned U.S. Pat. No. 5,693,085 to Buirge et al., and the disclosure of U.S. Pat. No. 5,693,085 is incorporated by reference herein. The stent may be an intraluminally implantable stent formed of a metal such as stainless steel or tantalum, a temperature-sensitive material such as Nitinol, or alternatively formed of a superelastic alloy or suitable polymer. Although a particular stent construction is shown with reference to the present invention, various stent types and stent constructions may be employed for the use anticipated herein. Among the various useful radially-expandable support members 28 include, without limitation, self-expanding stents and balloon expandable stents. The stents may be capable of radially contracting as well. Self-expanding stents include those that have a spring-like action which causes the stent to radially expand or stents which expand due to the memory properties of the stent material for a particular configuration at a certain temperature. Other materials are of course contemplated, such as stainless steel, platinum, gold, titanium, tantalum, niobium, and other biocompatible materials, as well as polymeric stents. The configuration of the radially-expandable support member 28 may also be chosen from a host of geometries. For example, wire stents can be fastened in a continuous helical pattern, with or without wave-like forms or zig-zags in the wire, to form a radially deformable stent. Individual rings or circular members can be linked together such as by struts, sutures, or interlacing or locking of the rings to form a tubular stent. [0027] Furthermore, the prosthesis 100 may be used with additional layers which may be formed of polymeric material and/or fabric. Furthermore, any layer or portion of the prosthesis 100 , including the tubes 10 A, 10 B, may be impregnated with one or more therapeutic and pharmacological substances prior to implantation of the prosthesis 100 for controlled release over an extended duration. It is anticipated that the prosthesis 100 can be partially or wholly coated with hydrophilic or drug delivery-type coatings which facilitate long-term healing of diseased vessels. Such a coating is preferably bioabsorbable, and is preferably a therapeutic agent or drug, including, but not limited to, anti-thrombogenic agents (such as heparin, heparin derivatives, urokinase, and PPack (dextrophenylalanine proline arginine chloromethylketone); anti-proliferative agents (such as enoxaprin, angiopeptin, or monoclonal antibodies capable of blocking smooth muscle cell proliferation, hirudin, and acetylsalicylic acid); anti-inflammatory agents (such as dexamethasone, prednisolone, corticosterone, budesonide, estrogen, sulfasalazine, and mesalamine); antineoplastic/antiproliferative/anti-miotic agents (such as paclitaxel, 5-fluorouracil, cisplatin, vinblastine, vincristine, epothilones, endostatin, angiostatin and thymidine kinase inhibitors); anesthetic agents (such as lidocaine, bupivacaine, and ropivacaine); anti-coagulants (such as D-Phe-Pro-Arg chloromethyl keton, an RGD peptide-containing compound, heparin, antithrombin compounds, platelet receptor antagonists, anti-thrombin antibodies, anti-platelet receptor antibodies, aspirin, prostaglandin inhibitors, platelet inhibitors and tick antiplatelet peptides); vascular cell growth promotors (such as growth factor inhibitors, growth factor receptor antagonists, transcriptional activators, and translational promotors); vascular cell growth inhibitors (such as growth factor inhibitors, growth factor receptor antagonists, transcriptional repressors, translational repressors, replication inhibitors, inhibitory antibodies, antibodies directed against growth factors, bifunctional molecules consisting of a growth factor and a cytotoxin, bifunctional molecules consisting of an antibody and a cytotoxin); cholesterol-lowering agents; vasodilating agents; and agents which interfere with endogenous vascoactive mechanisms. [0028] Various changes and modifications can be made in the present invention. It is intended that all such changes and modifications come within the scope of the invention as set forth in the following claims.

4y

This application claims the benefit of: U.S. Provisional Application Ser. No. 60/098,547, filed Aug. 31, 1998; U.S. Provisional Application Ser. No. 60/097,831, filed Aug. 31, 1998; U.S. Provisional Application Ser. No. 60/098,566, filed Aug. 31, 1998; U.S. Provisional Application Ser. No. 60/098,567, filed Aug. 31, 1998; and U.S. Provisional Application Ser. No. 60/098,573, filed Aug. 31, 1998. BACKGROUND The present invention generally relates to an open ended, woven fabric which is designed for use in a papermaking, cellulose or board manufacturing machine. The fabric has a plurality of loops at each end to form a seam for rendering the fabric endless. As will be known to those skilled in the art, papermaking machines generally include three sections commonly referred to as the forming, press and dryer sections. The present invention finds particular application in the press section of a papermaking machine. Typically, press felts include a supporting base, such as a woven fabric, and a paper carrying or supporting layer. Frequently, the paper support layer is a homogeneous, non-woven batt that has been affixed to the base. Base fabrics are typically woven fabrics which are used as an endless loop. Such an endless loop fabric may be woven endless with no seam or the fabric may be woven with two ends which are joined by a seam. Typical seams include pin type seams which utilize a pintle inserted through seam loops to close the fabric. Some prior art seams have employed threads in the seam area to increase batt adhesion. However, these efforts have not always produced the desired contact area or the desired interconnection between paper and machine side machine direction threads. As a result, there exists a need in seam loop construction to provide increased surface contact in the seam zone for better batt anchorage and a better interconnection between the paper and machine sides. SUMMARY The present invention relates to an open ended papermaker's fabric of a type woven from a longitudinal thread system and a transverse thread system. A plurality of seam loops are formed at each end of the fabric by the threads of the longitudinal thread system. A seam zone exists at each end of the fabric between the respective seam loops and the last thread of the transverse thread system. At least one additional transverse thread interwoven in at least one seam zone with the longitudinal thread system in a repeat pattern that includes a mid-plane float that extends between at least two pairs of paper side and machine side longitudinal threads. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 shows a portion of the longitudinal seam loops in a fabric having additional cross machine direction threads in accordance with the present invention. FIG. 2 is a front elevation of the seam loops and additional threads shown in FIG. 1 . FIG. 3 illustrates one weave repeat pattern for one of the additional threads. FIG. 4 illustrates one weave repeat for a second additional thread. FIG. 5 shows the weave repeats of FIGS. 3 and 4 combined but without the seam loops as shown in FIG. 2 . FIG. 6 is a top plan view of the combined weave patterns as illustrated in FIGS. 1, 2 and 5 . FIG. 7 illustrates the weave repeat for one additional thread in accordance with a second embodiment. FIG. 8 illustrates the weave repeat for a second additional thread in accordance with the second embodiment. FIG. 9 shows the weave repeats of FIGS. 7 and 8 in combination. FIG. 10 illustrates the weave repeat for one additional thread in accordance with a third embodiment. FIG. 11 illustrates the weave repeat for a second additional thread in accordance with the third embodiment. FIG. 12 shows the weave repeats of FIGS. 10 and 11 in combination. FIG. 13 illustrates the weave repeat for one additional thread in accordance with a fourth embodiment. FIG. 14 illustrates the weave repeat for a second additional thread in accordance with the fourth embodiment. FIG. 15 shows the weave repeats of FIGS. 13 and 14 in combination. FIG. 16 illustrates the weave repeat for one additional thread in accordance with a fifth embodiment. FIG. 17 illustrates the weave repeat for a second additional thread in accordance with the fifth embodiment. FIG. 18 shows the weave repeats of FIGS. 16 and 17 in combination. FIG. 19 illustrates the weave repeat for one additional thread in accordance with a sixth embodiment. FIG. 20 illustrates the weave repeat for a second additional thread in accordance with the sixth embodiment. FIG. 21 shows the weave repeats of FIGS. 19 and 20 in combination. DESCRIPTION OF THE PREFERRED EMBODIMENTS The preferred embodiments will be described with reference to the drawing figures wherein like numerals represent like elements throughout. Referring to FIG. 1, it shows a portion of the base fabric seam loops with additional threads woven in accordance with the present invention. The base fabric 1 comprises a top layer of MD longitudinal threads, 10 , 12 , 14 , 16 , 18 , 20 , 22 , and 24 , and a bottom layer of MD longitudinal threads, 11 , 13 , 15 , 17 , 19 , 21 , 23 and 25 . It will be understood that the top and bottom layers are essentially continuous threads which form the seam loops 35 - 1 to 35 - 8 between the top and bottom layers. Typically, the phantom CMD threads 2 - 5 are interwoven with the top and bottom MD longitudinal threads in a given repeat pattern to form the body of the fabric. The weave of the body of the fabric forms no part of the present invention. A seam zone 40 exists between the final CMD thread 2 and the seam loops 35 - 1 to 35 - 8 . Reference is now made to FIGS. 3, 4 and 5 . Although some benefits will be obtained with a single additional thread, the preferred embodiments employ two additional threads for more uniformity in the paper side surface. The two additional CMD threads 50 and 51 are interwoven in the seam zone 40 with both layers of MD threads 10 through 25 . Additional CMD thread 50 preferably weaves in a repeat pattern that passes over MD threads 10 - 11 , between MD thread pairs 12 - 13 , 14 - 15 , 16 - 17 , 18 - 19 , 20 - 21 , over threads 22 - 23 and under MD threads 24 - 25 . With reference to FIG. 4, the second additional thread 51 is woven in a complementary pattern to that of the thread 50 . The CMD thread 51 weaves in a repeat that passes between thread pairs 10 - 11 , 12 - 13 , over threads 14 - 15 , under threads 16 - 17 , over threads 18 - 19 and between thread pair 20 - 21 , 22 - 23 , 24 - 25 . The complementary pattern of the repeats can be seen from FIG. 5 . From FIG. 5 it can be seen that the shifted weave repeats of threads 50 and 51 result in a transverse weave repeat that appears as a plain weave on the paper side surface of the fabric, and a mid-plane float between each MD pair 10 - 11 , 12 - 13 , 14 - 15 , 16 - 17 , 18 - 19 , 20 - 21 , 22 - 23 , and 24 - 25 of the repeat. Finally, these weave repeats result in minimum interlacings on the machine side of the fabric. This allows the mid-plane floats to migrate relative to one another, thereby effectively creating a virtually continuous mid-plane float across the width of the fabric, see FIG. 6 . This is particularly beneficial in two-layer fabric constructions. With reference to FIGS. 7, 8 and 9 , there is shown a second embodiment of the present invention. In this embodiment, the transverse additional thread 55 weaves between MD threads 10 - 11 , under MD threads 12 - 13 , between MD threads 14 - 15 , over MD threads 16 - 17 , between MD thread pairs 18 - 19 , 20 - 21 , 22 - 23 and over MD threads 24 - 25 . The additional transverse thread 56 weaves in a complementary pattern. Thread 56 weaves over MD threads 10 - 11 , between MD thread pairs 12 - 13 , 14 - 15 , 16 - 17 , over MD threads 18 - 19 , between MD threads 20 - 21 , under MD threads 22 - 23 , and between MD threads 24 - 25 . As can be seen from FIG. 9, these complementary weave patterns produce a sheet side weave pattern with pairs of transverse weave knuckles alternating with pairs of MD threads that are over both of the additional transverse threads 55 and 56 . In addition to producing long continuous mid-plane floats, these patterns also increase the thread's transition length as it passes from layer to layer. Here, the threads 55 and 56 transition under three sheet side MD threads while passing under only one machine side MD thread. This embodiment provides minimum machine side surface interlacings, and long transitions that appear to provide a continuous a mid-plane float between six of the eight MD pairs. A third embodiment of the present invention is shown in FIGS. 10-12. The fabric of this embodiment repeats on twenty four MD threads 10 - 33 . The two additional threads 70 and 71 are interwoven in the seam zone 40 with both layers of longitudinal threads 10 through 33 . Additional CMD thread 70 weaves in a repeat pattern that passes between MD threads 10 - 11 , under MD threads 12 - 13 , between MD thread pairs 14 - 15 , 16 - 17 , and then weaves a continuous portion of plain weave with top layer MD threads 18 , 20 , 22 , 24 , 26 , 28 , 30 before transitioning down between MD threads 32 - 33 . With reference to FIG. 11, the second additional thread 71 is woven in a complementary pattern to that of thread 70 . Additional thread 71 weaves a plain weave construction with top layer threads 10 , 12 , 14 before transitioning into a mid-plane float between MD thread pairs 16 - 17 , 18 - 19 , 20 - 21 , 22 - 23 weaving under MD threads 24 - 25 and transitioning back to a mid-plane float between thread pairs 26 - 27 , 28 - 29 , 30 - 31 , 32 - 33 . As can be seen from FIG. 12, two additional threads interwoven in accordance with FIGS. 10 and 11 produce a weave repeat structure having the appearance of a plain weave in the upper layer and two crossover points 73 and 74 which are spaced apart by at least three MD threads. This results from the additional longitudinal thread being in a continuous portion 80 of the weave repeat with seven adjacent MD threads between transitions from the machine or paper side longitudinal threads. Since the repeat pattern extends over twelve pairs of MD threads with only a single interlacing in the machine side MD layer and the additional threads can shift relative to each other, threads 70 and 71 tend to act as one thread in a continuous plain weave on the top layer. As a result of the long transitions and the interlacing patterns, the additional threads can migrate relative to each other to produce the desired sheet side weave pattern while also providing mid-plane floats and long transitions. The combined threads provide two mid-plane floats, each floating between five of six MD thread pairs. With reference to FIGS. 13-15, there is shown a fourth embodiment of the present invention. In this fourth embodiment, the first additional thread 75 weaves between MD thread pairs 10 - 11 , 12 - 13 , beneath MD threads 14 - 15 , between MD thread pairs 16 - 17 , 18 - 19 , 20 - 21 , and then in a plain weave repeat with the upper layer MD threads 24 , 26 , 28 , 30 , 32 . The second additional thread 76 weaves in the mirror image of thread 75 . As shown by FIG. 15, the threads 75 and 76 produce a plain weave pattern on the paper sheet side, relatively long transitions which combine in a virtual mid-plane float and widely spaced crossover points 77 , 78 which encourage migration of the threads relative to each other. As with the prior embodiment, this embodiment provides a continuous portion 81 of the weave repeat that extends over at least five adjacent paper side longitudinal threads between transitions from the machine or paper side longitudinal threads and two mid-plane floats, each floating between five of six MD thread pairs. Referring to FIGS. 16-18, a fifth embodiment is shown. Additional CMD thread 100 weaves in a repeat pattern that passes between MD threads 10 - 11 , under MD threads 12 - 13 , between MD thread pairs 14 - 15 , 16 - 17 , floats over MD threads 18 - 23 , between MD threads 24 - 25 , floats over MD threads 26 - 31 and between MD threads 32 - 33 . With reference to FIG. 17, the second additional thread 101 is woven in a complementary weave pattern to that of thread 100 . Additional thread 101 weaves over MD threads 10 - 15 , between MD thread pairs 16 - 17 , 18 - 19 , 20 - 21 , 22 - 23 , under MD threads 24 - 25 and between MD thread pairs 26 - 27 , 28 - 29 , 30 - 31 , 32 - 33 . It will be noted from FIG. 17 that additional thread 101 forms two mid-plane floats between four pairs of MD threads 16 - 17 , 18 - 19 , 20 - 21 , 22 - 23 and 26 - 27 , 28 - 29 , 30 - 31 , 32 - 33 . As can be seen from FIG. 18, the two additional threads 100 , 101 as interwoven in FIGS. 16 and 17 produce a weave repeat structure having the appearance of an over three, under one repeat in the upper layer. The two crossover points, 103 , 104 are spaced apart by at least three MD threads. This creates a long continuous portion of the second additional thread 101 which generally forms mid-plane floats that complement the long transition of the first additional thread 100 . Since the repeat pattern extends over twelve pairs of MD threads with only a single interlacing in the machine side MD layer and the additional threads can shift relative to each other, threads 100 and 101 tend to act as one thread in a continuous over three, under one weave pattern on the top layer. With reference again to FIG. 16 and additional thread 100 , it can be seen that the weave repeat of thread 100 includes a subrepeat of over three, under one which repeats twice within the pattern. This weave repeat permits the relatively loose interlacing of the thread 101 but enables the pattern to be continued throughout the upper layer when the threads 100 , 101 are combined in accordance with FIG. 18 . Again, the combined threads 100 , 101 provide two mid-plane floats, each floating between five of six MD thread pairs. With reference to FIGS. 19-21, there is shown a sixth embodiment of the present invention. In this sixth embodiment, the first additional thread 105 weaves between MD thread pairs 10 - 11 , 12 - 13 , beneath MD threads 14 - 15 , between MD thread pairs 16 - 17 , 18 - 19 , 20 - 21 and then in two repeats of the subrepeat pattern of over two, under one with upper MD threads 22 , 24 , 26 , 28 , 30 , 32 . The second additional thread 106 weaves in the mirror image of thread 105 . As shown by FIG. 21, the threads 105 and 106 produce an over two, under one weave pattern on the paper sheet side, relatively long transitions in virtual five thread mid-plane floats and crossover points 107 , 108 which encourage migration of the threads relative to each other. As with the prior embodiment, this embodiment provides a weave repeat that includes two repeats of the subrepeat in adjacent paper side longitudinal threads between the transitions from the machine or paper side longitudinal threads. It will be appreciated that batt adhesion to the additional thread(s) of the various embodiments will be most improved on the sheet side surface but that improved machine side batt adhesion will be achieved. The additional CMD threads 50 , 51 , 55 , 56 ; 70 , 71 , 75 , 76 , 100 , 101 , and 105 , 106 can be multifilament, spun, braided, knitted, or bicomponent. If the thread is of a bicomponent nature, the bicomponent material may have a core material with a higher melting point surrounded by a covering of a lower melting point material. This allows the covering to melt and adhere to the batt material during finishing without affecting the core structure of the thread. Threads may be made from polymeric resins selected from a group consisting of polyamide, polyurethanes, polyesters, polyaramids, polyimides, polyolefins, polyetherketones, polypropylenes, PET, PBT, PTT, phenolics, and copolymers thereof.

4y

BACKGROUND [0001] The invention relates to the field of push button latches, and more particularly is a sealed push button latch that resist the ingress of moisture and debris, and has a drain feature in case moisture or debris does enter the push button latch. Push button latches are used in a variety of applications including for use in securing cabinet doors and glove box doors in a closed position, such as on golf carts and the like. Push button latches include a push button which actuates a latch which is released or retracted to allow opening of the door. [0002] A shortcoming of existing push button latches is that they are not completely resistant to the ingress of moisture and debris, and when they become wet or inundated with debris, this can interfere with the latch's optimal operation. Moreover, when this occurs, corrosion is more likely to take place and can lead to premature failure of the latch. Lastly, the designs of many push latches remain unnecessarily complex and expensive to manufacture and assemble. [0003] There accordingly remains a need for improved sealed push button latches that are simple in design, easy to assemble, reliable in operation, low in cost, resistant to moisture and debris infiltration, and self-draining. SUMMARY OF THE INVENTION [0004] The invention comprises a sealed push button latch having a housing with an outer sidewall defining an upper cavity and a lower cavity separated by a wall with an aperture. The upper cavity preferably has a vertically oriented notch on its sidewall. The lower cavity has a latch opening formed in its sidewall, and preferably has drain/return clip apertures formed on the sidewall of the housing. These drain/return clip apertures are preferably formed generally opposite the latch opening and are provided so that any liquid that might have entered to housing will freely drain therefrom, regardless of the orientation and position of the push button latch mounted to a door. The push button (with or without a keyed lock) axially moves up and down in the upper portion of the housing to actuate a latch. [0005] In cases where the push button has an integral keyed lock, and it is desirable to provide for additional sealing between the keyed lock and the push button, a seal, e.g., such as an O-ring, will be placed in a groove formed around an outside wall of the keyed lock. The keyed lock will then be engaged with the push button, with the O-ring providing for additional sealing between the keyed lock and the push button. To provide for sealing between the push button and the housing, a seal, e.g., such as an O-ring, will be placed in a groove that will be formed around an outside wall of the push button. This O-ring will contact with the housing and help prevent the ingress of water and debris between the push button and the housing. [0006] The push button (or its keyed lock) connects at its bottom to an actuator having a pin, which pin passes through the aperture in the separating wall and extends downwardly in the lower portion. A coil spring positioned in the upper cavity is placed above the separator wall and around the actuator's pin and pushes it up into contact with the push button. This also biases the push button upwardly. A latch leg with a protrusion extending downwardly from the push button is aligned so that the protrusion is received in the vertically oriented notch on the sidewall of the housing, and prevents the push button from becoming separated from the upper cavity of the housing. In cases where the push button has a keyed lock, turning the keyed lock will rotate the actuator. The actuator has tabs and grooves formed thereon, which when turned by the keyed lock in a locked position will be aligned with stop rails and a guide rail formed on the inside wall of the upper cavity to prevent the push button from being depressed and actuating the locking latch. When the keyed lock is in its opened position, the actuator will be rotated such that its tabs and grooves clear the stop rails and the guide rail of the housing, so that the push button is free to be pushed down to operate the locking latch. [0007] The locking latch is located in the lower cavity. The locking latch has an outwardly facing slanted slam surface and an interior ramp surface which is aligned to be impinged by downward motion of the actuator's pin. In an extended mode of the locking latch, the outwardly facing slanted slam surface will project out of the housing. The slanted slam surface and the interior ramp surface both slant inwardly and downwardly towards the middle of the locking latch. A latch spring is located in the lower cavity and acts to bias the locking latch to project outside of the housing. The locking latch is adapted to be moved back into the lower housing portion in response to both a downward movement of the actuator and its pin, which pin impinges on the ramp surface, and the impact of the slanted slam surface of the locking latch with a strike plate. [0008] An optional return clip can be engaged with the housing to help maintain a tight and vibration-free contact between the sealed push button latch and the door frame to which the door is hinged, and also helps to pop open the closed door. The return clip will include a front lip portion from which extends two spaced apart forks. At the ends of the spaced apart forks are protrusions. The spaced apart forks are inserted into the latch opening above the locking latch, and the protrusions are passed through the drain/return clip apertures and thus secure the return clip to the housing. BRIEF DESCRIPTION OF THE DRAWINGS [0009] FIG. 1 is an exploded view showing various parts of an exemplary embodiment of a sealed push button latch of the invention. [0010] FIG. 2 is a partially exposed view of the housing of the push button latch of FIG. 1 . [0011] FIG. 3 is a top view of the housing of the push button latch of FIG. 1 . [0012] FIG. 4 is a perspective view of the push button and its engaged keyed lock of the push button latch of FIG. 1 . [0013] FIG. 5 is another perspective view of the push button and its engaged keyed lock of FIG. 4 , but rotated by 180 degrees. [0014] FIG. 6 is a bottom view of the push button and keyed lock of the push button latch of FIG. 1 . [0015] FIG. 7 is a bottom view of the actuator of the push button latch of FIG. 1 . [0016] FIG. 8 is a side view of the push button and keyed lock engaged with the actuator in a locked mode. [0017] FIG. 9 is a bottom view of the push button with attached actuator in a locked mode of FIG. 8 . [0018] FIG. 10 is a side view of the push button with attached actuator in an unlocked mode. [0019] FIG. 11 is a bottom view of the push button with attached actuator in an unlocked mode of FIG. 10 . [0020] FIG. 12 is front view of the housing of the push button latch of FIG. 1 . [0021] FIG. 13 is a rear view of the housing of the push button latch of FIG. 1 . [0022] FIG. 14 is a front view of the exemplary embodiment of the assembled push button latch of FIG. 1 . [0023] FIG. 15 is a left side view of the exemplary embodiment of the push button latch of FIG. 14 . [0024] FIG. 16 is a right side view of the exemplary embodiment of the push button latch of FIG. 14 . [0025] FIG. 17 is a back view of the exemplary embodiment of the push button latch of FIG. 14 . [0026] FIG. 18 is a top view of the exemplary embodiment of the push button latch of FIG. 14 . [0027] FIG. 19 is a bottom view of the exemplary embodiment of the push button latch of FIG. 14 . [0028] FIG. 20 is a longitudinal cross-section view of the assembled push button latch through view lines 20 - 20 of FIG. 14 with the push button in an un-depressed mode and with the locking latch projecting outside of the housing. [0029] FIG. 21 is longitudinal cross-section view of the assembled push button latch of through view lines 21 - 21 of FIG. 15 and with the locking latch projecting outside of the housing. [0030] FIG. 22 is a longitudinal cross-section view of the assembled push button latch with the push button in a depressed mode to retract the locking latch into the housing. [0031] FIG. 23 is a left side perspective view of the push button latch of FIG. 14 mounted on a door in a horizontal position. [0032] FIG. 24 is a right side perspective view of the push button latch of FIG. 14 mounted on a door in a horizontal position. [0033] FIG. 25 is a left side perspective view of the push button latch of FIG. 14 mounted on a door which is canted slightly from a vertical position and with its locking latch directed generally upwards and with its drain/return clip apertures directed generally downwards. [0034] FIG. 26 is a left side perspective view of the push button latch of FIG. 16 mounted on a door which is canted slightly from a vertical position and with its locking latch directly generally downwards. DETAILED DESCRIPTION OF THE INVENTION [0035] Turning now to the drawings, FIG. 1 is an exploded view showing various parts of an exemplary embodiment of a sealed push button latch 10 of the invention. It includes a push button 12 , and in the case where a locking feature is desired, a keyed lock 14 . An opening 16 is formed in the push button 12 into which the keyed lock 14 is inserted. For provision of improved sealing between the keyed lock 14 and the push button 12 , a groove 18 is formed around an outside wall 20 of the keyed lock 14 . The keyed lock 14 has a head 22 with a key entrance. A seal, such as an O-ring 24 A, is placed in the groove 18 . The push button 12 has an outer wall 26 on which is formed an optional groove 28 . For provision of improved sealing between the push button 12 and a housing 50 into which the push button 12 engages, a seal, such an O-ring 24 B, is placed in the groove 28 . The push button 12 has a latch leg 30 . An actuator 32 is provided which is adapted to engage with the keyed lock 14 . The actuator 32 has an engagement 34 formed on its head 36 . The head 36 has tabs 38 formed thereon, the purpose of which will be described further below. A pin 40 extends downwardly from the head 36 . A coil spring 42 is placed around the pin 40 and biases the actuator 32 upwardly so that the engagement 34 in the head 36 of the actuator is brought into contact with a complementary engagement 44 on the bottom of the keyed lock 14 , which when the keyed lock is turned, will cause the actuator 32 to also rotate. The housing 50 has an upper opening 52 sized to slidably receive the push button 12 . The housing 50 also has an enlarged retention head 54 , and preferably has threads 56 formed on an outer wall 58 of the housing 50 below the retention head 54 . The housing 50 is preferably non-cylindrical, e.g., it can have flats 60 formed on sides thereof, to prevent the housing 50 from rotating once it is mounted in place, such as on a door “D”, as best shown in FIGS. 23-26 . A latch opening 62 is formed through the outer wall 58 and communicates with a lower cavity 64 of the housing 50 . A vertically oriented notch 66 is formed in the sidewall 58 of the housing 50 , and is adapted to receive the latch leg 30 of the push button 12 . The latch leg 30 has a protrusion 68 at its end which will be captured in the vertically oriented notch 66 and prevent the push button 12 and its keyed lock 14 from being completely withdrawn from the housing 50 once the push button 12 has been inserted therein. This likewise makes assembly of the sealed push button latch of the invention extremely simple and a tool-free operation. [0036] A locking latch 70 is adapted to be received in the lower cavity 64 and transversely slide therein and be extendable outside of the latch opening 62 . The locking latch 70 has a front slanted slam surface 72 which extends up and out from a bottom 74 to a top 76 of the locking latch 70 . A latch spring 78 is placed in the lower cavity 64 between the locking latch 50 and acts to bias the locking latch 70 so that its front slanted slam surface 72 extends outside of the latch opening 62 , as shown FIGS. 14-16 and 21 . An optional return clip 80 can be used to help stabilize the sealed push button latch 10 when it is latched to a frame and prevent the door from rattling. The return clip 80 has two spaced apart forks 82 with protrusions 84 at ends thereof, and a front lip portion 86 . Stops 88 are located rearwardly of the lip 86 . As the return clip 80 is engaged with the housing 50 , the two spaced apart forks 82 will flex together and the protrusions 84 at the ends of the forks 82 will pass through drain/return clip apertures 90 formed through the outer wall 58 of the housing 50 opposite the latch opening 62 . If desired, additional indents 92 can be formed at the top of the lower cavity at the entrance of the latch opening 62 to accommodate the passage of the forks 82 . After the return clip 80 is fully inserted into place with the housing 50 , the stops 88 will rest against the outer wall 58 of the housing 50 and the two forks 82 will spring apart and the protrusion 84 will lock in place in the drain/return clip apertures 90 . A lock washer 96 and nut 98 are used to retain the sealed push button latch 10 to a closure, such as a door “D”, as shown in FIGS. 23-26 . [0037] FIG. 2 is a partially exposed view of the housing 50 the push button latch 10 of FIG. 1 , and FIG. 3 is a top view of same. The housing 50 includes the upper opening 52 sized to slidably receive the push bottom 12 (not shown). The housing 50 also has an oversized retention head 54 that will seat on an aperture formed in closure, such as shown in FIGS. 23-26 . The housing 50 preferably has threads 56 formed on its outer wall 58 below the head 54 . The latch opening 62 is formed through the sidewalls and communicates with a lower cavity 64 of the housing 50 . The vertically oriented notch 66 is formed in the sidewall 58 of the housing 50 . A dividing wall 100 is located above the lower cavity and has an aperture 102 through which will pass the pin 40 of the actuator 32 , as shown in FIGS. 20-22 . The lower cavity 64 has a lower end wall 104 , which can have tracks 106 formed thereon to guide the sliding motion of the locking latch 70 , as shown in FIG. 20 . A spring keeper 108 is used to retain the coil spring 78 in place. Above the dividing wall 100 is the upper cavity 110 . It is in the upper cavity 110 that the push button 20 is received. Formed on inside walls 112 of the housing 50 is an elongate push button guide rail 114 . The push button 20 has a complementary elongate slot 116 formed on an outer surface thereof (see FIG. 4 ), and when the push button 20 is placed in the upper cavity 110 , the push button 20 will thereby be allowed to move up and down but not rotate by virtue of the elongate push button guide rail 114 riding in the complementary elongate slot 116 . Also located on the inside sidewalls of the upper cavity 110 are stops 118 . The stops 118 are designed so that when the keyed lock 14 is operated and its locked position, the actuator 32 will be turned so that its tabs 38 will be aligned to intersect with the stops 118 , and thereby prevent the push button 12 from being pushed down. However, when the keyed lock 14 is in its opened position, the actuator 32 is turned so that its tabs 38 clear the stops 118 , thereby allowing the push button 12 to be pushed down. The upper region of the upper cavity 110 is defined by smooth inner sidewalls 130 which will provide a contact surface for the O-ring 24 B on the push button 12 in the groove 28 to ride along and provide a water tight yet moveable seal, which is best shown in FIGS. 20-22 . An inner rim 132 is formed along the inside of the retention head 54 extends slightly inwardly to create a slightly smaller diameter opening. [0038] FIG. 4 is a first side view of the push button assembled with its keyed lock 12 +14 of the push button latch of FIG. 1 , and FIG. 5 is another side view of same rotated along its axis by 180 degrees. FIG. 6 is a bottom view of same. The push button 12 has an outer wall 26 with an O-ring 24 B placed in the groove thereon (not shown). The latch leg 30 with it protrusion 68 are also shown. Also shown is the complementary engagement 44 on the bottom of the keyed lock 14 , and the elongate slot 116 . [0039] FIG. 7 is a bottom view of the actuator 32 . The engagement 34 formed on its head 36 and the tabs 38 formed thereon are shown. Also shown is a notch 130 . The notch is designed to allow the latch leg 30 and its terminal protrusion 68 to swing inwardly as the push button 12 is slide into the upper cavity 110 during assembly of the push button lock. [0040] FIG. 8 is a side view of the push button with attached actuator 12 +14 in a locked mode, and FIG. 9 is a bottom view of same. The O-ring 24 B is positioned in the groove (not shown) in the sidewall 26 of the push button 12 . The different positions of the tabs 38 are shown as the keyed lock 14 is moved from the locked mode, to the unlocked mode, shown in FIG. 10 , which is a side view of the push button with attached actuator 12 +14 in an unlocked mode, and FIG. 11 , which is a bottom view of same. Also shown is how the notch 130 aligns with the latch leg 30 to allow it and its proximal protrusion 68 to swing inwardly during insertion of the push button lock 12 into the upper cavity 110 of the housing 50 . In these views, the complementary elongate slot 116 formed on an outer surface 26 of the push button 12 is shown, as well as the pin 40 of the actuator 32 . [0041] FIG. 12 is front view of the housing 50 and FIG. 13 is a rear view of the housing 50 of the push button latch 10 of FIG. 1 . The various features shown include the retention head 54 , the threads 56 formed on the outer wall 58 of the housing below the head 54 , the drain/return clip apertures 90 , indents 92 , the vertically oriented notch 66 , its upper end 124 , the dividing wall 100 between the lower cavity 64 and the upper cavity, the lower end wall 104 with its tracks 106 , and the spring keeper 108 . [0042] FIG. 14 is a front view, FIG. 15 is a left side view, FIG. 16 is a right side view, FIG. 17 is a back view, FIG. 18 is a top view, and FIG. 19 is a bottom view of the exemplary embodiment of the assembled push button latch 10 . In these views there are shown the push button 12 , the keyed lock 14 , the retention head 54 , the threads 56 formed on the outer wall 58 of the housing below the head 54 , the drain/return clip apertures 90 , the indents 92 , the vertically oriented notch 66 , and the protrusion 68 on the latch leg 30 (not shown), which protrusion 68 captures at the upper end 124 of the vertically oriented notch 66 , the locking latch 70 with its front slanted slam surface 72 , and the lower end wall 104 . In FIG. 18 the keyed locked 14 is shown. [0043] Turning to FIGS. 20-22 , there are shown various cross-sections views of the push button latch 10 . FIG. 20 is a longitudinal cross-section view of the assembled push button latch 10 through view lines 20 - 20 of FIG. 14 with the push button 10 in an un-depressed mode with the locking latch 70 extending outside of the housing 50 . FIG. 21 is longitudinal cross-section view of the assembled push button latch through view lines 21 - 21 of FIG. 15 with the push button in an un-depressed mode. Lastly, FIG. 22 is a longitudinal cross-section view of the assembled push button latch with the push button in a depressed mode to retract the latch into the housing. The push button and its keyed locked 12 +14 are retained in the upper cavity 110 by virtue of the protrusion 68 on the latch leg 30 being captured at the upper end 124 of the vertically oriented notch 66 . A lower end 122 of the pin 40 of the actuator 32 will pass through the aperture 102 in the dividing wall 100 and contact an inwardly slanted surface 120 of the locking latch 70 . One end of the coil spring 78 is retained by the spring keeper 108 and the other end of the coil spring 78 is retained in a tunnel 126 formed through a back wall 128 of the locking latch 70 . The bottom 74 of the locking latch 70 rides on the lower end wall 104 of the housing and the track 106 located therein, and the top 76 of the locking latch 70 rides generally below the dividing wall 100 . The upwardly and outwardly slanted surface 72 of the locking latch is available for contact with a slam surface, such as a catch on a door frame (not shown.) The coil spring 78 will provide a biasing force that tends to bias the locking latch 70 out of the latch opening 62 of the lower cavity 64 , with the lower end 122 of the pin 40 extending into the locking latch 70 to prevent it from becoming completely separated from the lower cavity 64 . The coil spring 42 is placed around the pin 40 and at its upper extreme contacts an underside of the head 34 of the actuator, with the lower extreme of the coil spring 42 contacting the dividing wall 100 . As can be best seen in FIG. 22 , when the push button 12 is in the opened position and is pushed down into the housing 50 , the lower end 122 of the pin 40 of the actuator 32 will impinge on the inwardly slanted surface 120 of the locking latch 70 and cause it to be drawn into the lower cavity 64 , thereby compressing the coil spring 78 . In these figures, the O-ring 24 B is seated in the groove 28 on the push button 12 and will lightly ride along the inside walls 130 of the housing 50 to provide a water resistant seal therewith. In the locked position shown in FIGS. 20 and 21 , the O-ring 24 B will also seat against the inner rim 132 formed along the inside of the retention head 54 . This seating of the O-ring 24 B with the inner rim 132 will help prevent the chance for water, other fluids, or debris from entering the push button lock. Indeed, in the normal condition, the push button latch 10 will be un-depressed, and therefore, a good seal will be maintained. When the push button 12 is depressed, however, the O-ring 24 B will be moved out of contact with the inner rim 132 , and therefore, a less tight seal between the O-ring 24 B and the inside walls 130 is required, thereby helping to ensure that the operation of the push button latch is smooth and unimpeded. This also eliminates the need for an unnecessary strong coil spring 42 to return the push button 12 to its locked position of FIGS. 20 and 21 . Also shown is the locking engagement between the engagement 34 in the head 36 of the actuator 32 and the complementary engagement 44 of the keyed lock 14 . The coil spring 42 ensures that the actuator 32 is maintained in contact with the keyed lock 14 . Also shown is the O-ring 24 A which is placed in the groove 18 on the outside wall 20 of the keyed lock 14 . Once the keyed lock 14 is inserted into the push button 12 , its locks into place, and the O-ring 24 A helps prevent any moisture or debris from traveling between the outside walls of the keyed lock 14 and the inside 140 of the inner walls of the push button 12 . [0044] FIG. 23 is a left side perspective view of the push button latch 10 of FIG. 15 mounted on a door “D” which is in a generally horizontal position and FIG. 24 is a right side perspective view of the push button latch 10 mounted on door “D” which is in a generally a horizontal position. The nut 98 is used to retain the sealed push button latch 10 with its retention head 54 resting on one side of the door “D” and with the push button and keyed lock 12 +14 accessible on an “outside” of the door “D”. In case moisture or debris were to enter the sealed push button lock 10 from the outside, such moisture could pass though the housing 50 and exit through the latch opening 62 formed in the housing 50 around edges of the locking latch 70 , and/or thorough the drain/return clip apertures 90 formed through the outer wall 58 of the housing 50 . [0045] FIG. 25 is a left side perspective view of the push button latch 10 mounted on the door “D” and being canted slightly from a vertical position and with its locking latch 70 directly generally upwardly and with the drain/return clip apertures 90 being at a lower point. In this position, any moisture that might have entered the push button latch 10 can drain out through the drain/return clip apertures 90 , which are not completely block by the retention clip 80 . FIG. 26 is a left side perspective view of the push button latch 10 mounted on the door “D” and being canted slightly from a vertical position and with its locking latch 70 directly generally downwardly. In this position, any moisture that might have entered the push button latch 10 can drain out through the latch opening 62 formed in the housing 50 . In FIGS. 25 and 26 , the optional return clip 80 is engaged with the housing 50 , and can be used to help prevent the door “D” from rattling when it is closed and to provide a spring force that will tend to spring the door “D” open as soon as the push button lock is activated to withdraw the locking latch 70 into the housing 50 . The return clip 80 is engaged with the housing 50 so that its two spaced apart forks 82 with protrusions 84 at ends thereof are inserted into the drain/return clip apertures 90 . The front lip portion 86 will extend generally above the top locking latch 70 . The stops 88 located rearwardly of the front lip portion 86 will rest against the outside of the housing. As the return clip 80 is engaged with the housing 50 , the two spaced apart forks 82 will flex together and the protrusions 84 at the ends of the forks 82 will pass through drain/return clip apertures 90 formed through the outer wall 58 of the housing 50 opposite the latch opening 62 . Inclusion of the optional indents 92 in the housing 50 provide a place for the forks 82 to remain in place without impinge on the locking latch 70 . Even when engaged with the housing, the optional return clip 80 will not interfere with draining from the drain/return clip apertures 90 . [0046] Although the sealed push button lock 10 has been described as utilizing the O-rings 24 A and/or 24 B to provide for improved sealing and water-tightness, if the application is one where moisture is not expected to be an issue, such as the interior of an automobile, then one or both of the seals need not be included. However, in applications where moisture and debris entering the push button lock is more of a concern, such as golf carts, which are often cleaned by spraying down with water and detergent after use, and there is a chance that water, detergent, other moisture, and debris of entering the push button lack, including the seals is highly beneficial. [0047] Although embodiments of the present invention have been described in detail hereinabove in connection with certain exemplary embodiments, it should be understood that the invention is not limited to the disclosed exemplary embodiments, but, on the contrary is intended to cover various modifications and/or equivalent arrangements included within the spirit and scope of the present invention.

4y

[0001] The present invention relates in general to an emergency release tool for a connector designed for sub sea operation, and to a method for emergency release of such clamp connector, applying the tool. [0002] More specifically, the present invention relates to an emergency release tool for a clamp connector adapted for sub sea operation, which tool is applied, when release of a subsea connector by normal mechanism is not possible. [0003] More particularly, the present invention relates to an emergency release tool according to the preamble of claim 1 and to a method for releasing a subsea clamp connector, according to the preamble of claim 9 . [0004] The clamp connector emergency release tool is adapted to be handled and operated remotely by a work class ROV tool. TECHNICAL BACKGROUND OF THE INVENTION [0005] In onshore and offshore operations such as for hydrocarbon exploration and production, application of subsea clamp connectors is very common. These connectors are applied for attachment of various subsea assemblies. Examples may be marine risers, production flow lines attached to well heads and so on. [0006] It is also common knowledge that subsea assemblies need to be removed after the desired operation is over, or if there is some problem with the line. For that purpose, the clamp connectors securing the line need to be unlocked/released in a subsea environment. This has to be done remotely with the assistance of a ROV carrying a ROV tool. [0007] After operation for a substantial period of time, the clamp connector may get jammed up and normal release of the connector is not possible by applying conventional torque tool. In such a case, an emergency release tool needs to be applied, which should be possible by subsea operation of the ROV. [0008] Over the years, there has been a requirement for such emergency release tool, for release of clamp connectors, which is capable of sub sea operation when remotely applied, such that the connector is released in a safeguarded manner, ensuring proper detachment of the concerned subsea assemblies. However, significant achievement in this respect is yet to be achieved. [0009] The present invention relates to a clamp connector emergency release tool designed for subsea operations when normal release of a clamp connector is not possible, which tool is handled and operated by a work class ROV tool able to cut around the jack screw of a clamp connector in order to open up the clamp connector. [0010] Granted U.S. Pat. No. 5,273,376 teaches an emergency release tool for forcefully removing a marine assembly from a subsea assembly. The marine assembly has a first flange and the sub sea assembly has a second flange. The tool has a U-shaped frame which is transported and positioned between the flanges by ROV. Hydraulic means is mounted on the frame. This hydraulic means exerts pressure on the flanges when it is actuated by a hydraulic fluid. The hydraulic fluid is supplied from means located on ROV. On doing so, the hydraulic means generates a force normal to the frame and pushes the flanges apart. [0011] From the paragraph above, it should be understood that this US patent leaves scopes of malfunctioning of the complicated arrangement and the methodology applied, which involves forcefully prying and breaking the clamps open. This requires a much larger force to be generated than cutting through the clamp. Hence, achieving the emergency release in a safeguarded manner, enabling ensured and clear release is not achieved. [0012] US 2005145389A1 discloses a subsea well casing cutting tool comprising a casing gripper and a rotary cutter drive assembly. This merely discloses an arrangement for straightaway cutting a subsea well casing and removing it, for example, when it is abandoned. It is not directly related to sub sea emergency release of a clamp connector used for locking sub sea assemblies. [0013] Similar comments as above are applicable in respect of granted U.S. Pat. No. 4,557,628, which discloses an apparatus and method for remotely cutting broken parts of an underwater upright structure for emergency removal of such broken parts. Hence, this also is not directly related to sub sea emergency release of a clamp connector, used for locking sub sea assemblies. [0014] Similarly, US 2008/0304915A1 discloses a method and device for attaching a cutting assembly to a sea bed, the cutting assembly comprising a frame work for holding the object to be cut and a cutter head. [0015] All the above prior art relate to sub sea operation and involve cutting operation including a cutter drive. None of these have the teaching of the present invention as described herein and claimed in the appended claims. OBJECTS OF THE INVENTION [0016] It is the principal object of the present invention to provide an emergency release tool, capable of releasing a jammed up clamp connector and suitable for sub sea operation by means of a work class ROV, such that the connector is released in a safeguarded manner, enabling clear and emergency release of the clamped sub sea assemblies. [0017] It is a further object of the present invention to provide an emergency release tool for use on a clamp connector suitable for sub sea operation by means of a work class ROV, which works when conventional techniques applying a torque tool fails. [0018] It is yet another object of the present invention to provide an emergency release tool for use on a clamp connector which is adapted to be applied in emergency situations to release a “Horizontal Connection Module” (HCM) from a “Clamp Connector” (CC), if the usual method of applying the conventional torque tool fails. [0019] It is a further object of the present invention to provide an emergency release tool for use on a clamp connector, suitable for sub sea operation by means of a work class ROV which is simple in use and construction, and does not involve complicated operating steps or components. [0020] It is another object of the present invention to provide a method for releasing a sub sea clamp connector by applying an emergency release tool with the help of a work class ROV, such that the connector is released in a sacrosanct manner, enabling clear and emergency release of the clamped sub sea assemblies. [0021] How the foregoing objects are achieved and some other advantageous features, still not disclosed in prior art, will be clear from the following non-limiting description. [0022] All through the specification including the claims, the words, “connector”, “clamp connector”, “hydraulic fluid”, “work class ROV”, “piston”, “cylinder assembly”, “hole saw”, “hydraulic cylinder”, “jack screw” are to be interpreted in the broadest sense of the respective terms and includes all similar items in the field known by other terms, as may be clear to persons skilled in the art. Restriction/limitation, if any, referred to in the specification, is solely by way of example and understanding of the present invention. SUMMARY OF THE INVENTION [0023] Accordingly, the present invention provides a clamp connector emergency release tool designed for subsea operations, when normal release of a subsea clamp connector is not possible. This tool is handled and operated remotely by a work class ROV tool. The tool according to the invention, includes a clamp connector adapter housing arranged to engage with and connect to the clamp connector body, a rotatable hole saw mounted on the adapter housing, a rotary motor in driving connection with the rotatable hole saw and a piston and cylinder assembly arranged to advance the rotatable hole saw into the clamp connector body while cutting around a jack screw of the clamp connector, in order to separate the jack screw together with a threaded portion of the clamp connector body from the remainder of the clamp connector body, for its perfect releasing. [0024] Preferably, the rotary motor is hydraulically operated and driven and the piston and cylinder assembly are hydraulically actuated. [0025] Preferably, the tool also includes an upper pack box and lower pack box for having hydraulic fluid sealing arrangement. [0026] In one preferred embodiment, the tool includes an indicator for indicating the engage position and disengage position of the hole saw, with respect to the clamp connector body. [0027] Moreover, the tool may include a ROV handle arranged on the hydraulic piston cylinder. [0028] Preferably, the tool includes guiding means arranged on the clamp connector adapter housing for facilitating its landing on the clamp connector body. [0029] More preferably, the tool includes a landing indicator for indicating correct landing of the housing on the clamp connector body. [0030] In one embodiment the clamp connector is of the kind having two hinges and three links. [0031] The present invention also provides a method of emergency release of a subsea located clamp connector by use of a connector emergency release tool, when normal release of a clamp connector is not possible, which tool is handled and operated by a work class ROV tool. The method comprises operating the tool and advancing it into the clamp connector body by cutting the clamp connector body adjacent to its jack screw. This ensures cutting loose the jack screw together with a thread portion of the clamp connector body for separating the jack screw from the clamp connector body. Hence, perfect release of the subsea clamp connector is ensured. [0032] Preferably, the cutting operation as described in the preceding paragraph, takes place by use of a hole saw driven by a rotary motor and advanced by means of a hydraulic piston and cylinder. BRIEF DESCRIPTION OF THE ACCOMPANYING FIGURES [0033] Having described the main features of the invention above, a more detailed and non-limiting description of a preferred embodiment is given in the following with reference to the drawings, in which: [0034] FIG. 1 a and 1 b illustrate an isometric view and a sectional view respectively, of the emergency release tool according to the present invention. [0035] FIG. 2 a illustrates the emergency release tool according to the present invention, mounted on a clamp connector. [0036] FIG. 2 b illustrates an enlarged view of a portion shown in FIG. 2 a to clearly show the landing indicator. [0037] FIG. 3 illustrates in more detail the position indicator of the emergency release tool according to the present invention. [0038] FIG. 4 a illustrates a longitudinal cross section through the emergency release tool and the clamp connector according to the present invention. [0039] FIG. 4 b illustrates an enlarged view of a portion shown in FIG. 4 a to clearly show the position of the hole saw on the clamp connector body. [0040] FIG. 5 a illustrates a stage when the emergency release tool illustrated in FIG. 4 a has advanced into the body of the clamp connector. [0041] FIG. 5 b illustrates an enlarged view of the portion of FIG. 5 a , that shows the stage where the hole saw has already cut through the main clamping portion. [0042] FIG. 6 illustrates in more detail the position indicator of the emergency release tool according to the present invention, in engaged position. [0043] FIG. 7 a illustrates the emergency release tool mounted on the clamp connector as in FIG. 2 a when seen from the front. [0044] FIG. 7 b illustrates an enlarged view of a portion shown in FIG. 7 a to clearly show the position indicator in disengaged position. DETAILED DESCRIPTION OF THE INVENTION [0045] The following provides a detailed non-limiting description of a preferred embodiment of the present invention which is purely exemplary. [0046] The present invention discloses a clamp connector emergency release tool designed for subsea operations when normal release of a clamp connector is not possible. This tool is handled and operated by a work class ROV tool such that the clamp connector is released by cutting the body of the clamp connector, around the jack screw, for opening up the clamp connector. [0047] The emergency release tool has a simple construction and can be applied by the ROV in subsea condition, for cutting around the jack screw as explained in the preceding paragraph. Here lies the uniqueness of the emergency release tool of the present invention which achieves releasing of a clamp connector, in a subsea environment in a sacrosanct manner, such that the clamped assemblies may be removed. [0048] The present invention also relates to a method of releasing a subsea located clamp connector by applying the connector emergency release tool when normal release of a clamp connector is not possible. This may happen after prolonged sub sea operation, when the clamp connector gets jammed up. [0049] Thus, the emergency release tool according to the present invention can be effectively applied in emergency situations to release a “Horizontal Connection Module” (HCM) from a “Clamp Connector” if the usual method, using the conventional “Torque Tool”, fails. [0050] The unique constructional features of the emergency release tool and the method of its working is explained later, in detail with reference to the accompanying drawings. It is known and as stated under the heading “Technical Background of the Invention”, sub sea clamp connectors are applied for attaching sub sea assemblies. [0051] A clamp connector 14 (best shown in FIG. 2 a ) of this kind has three arc shaped links 14 ′ hingedly connected to each other. Each link 14 ′ is made up by a pair arc shaped link pieces placed in parallel a distance apart from each other and connected by pivot pins providing the hingedly connection between the respective links 14 ′. Such clamp connectors, when activated, forces two pipe flanges axially towards each other. The activation takes place by turning a jack screw by use of a conventional torque tool. [0052] The jack screw 15 (best shown in FIG. 4 a ) is simply a heavy gauge bolt with external threads through most of its entire extension and terminates in a square or hexagon bolt head, normally not wider than the bolt shaft. As stated above, such clamp connectors 14 are generally of a two hinged 14 ″ construction, with three links 14 ′ and can be opened up to be withdrawn from a pipe joint, or closed to be tightened around the pipe joint. The connector 14 is able to retain a metal-to-metal seal intended to be located between the pipe flanges. [0053] The jack screw 15 passes through a centrally located seal plate and transversally extending blocks arranged on respective clamp connector link ends, with the blocks facing each other when the clamp connector is closing. One of the blocks has internal left hand threads, while the other is provided with internal right hand threads, which engage with corresponding threads on the jack screw 15 . The jack screw 15 is rotatable in the seal plate, but still retained by the plate. This is the location where the right hand and left hand threads of the jack screw 15 meet. Thus, by turning the jack screw 15 in one direction the blocks are drawn towards each other in order to tighten the clamp connector 14 . By turning the jack screw 15 in the other direction, the clamp connector 14 is opened up and released. The configuration of the clamp connector 14 is not shown in closer detail, since this design is not part of the present invention and is per se known to persons skilled in the art. [0054] The emergency release tool 1 ′ is illustrated in figures la and lb. As shown in FIG. 1 a , the tool 1 ′ has a hydraulic cylinder comprising of a lower cylindrical housing 5 , encasing another housing 4 of a hydraulic piston 3 (best shown in the cross-sectional view 1 b ). A ROV handle 8 is installed on the cylindrical housing 5 for operating by a ROV (not shown). The tool 1 ′ also has a clamp connector adapter housing 7 at its lower end. This housing 7 is adapted to land on a clamp connector body 14 (best shown in FIGS. 2 a , 4 a , 5 a ) and engage therewith. The housing 7 is also provided with disengage/engage position indicator 6 / 6 ′, the functions of which are explained later. [0055] As shown in FIG. 1 b , a rotation rod 10 is operatively connected to a hydraulic rotary motor 1 . FIG. 1 a also shows the motor bracket 2 . A hole saw 11 is connected to the rotation rod 10 , which in turn is forced down by the hydraulic piston 3 during operation. The rod 10 is rotatable by the motor 1 , so that the rod 10 acts as the rotatable drive of the hole saw 11 . [0056] The FIG. 1 b also shows an upper pack box 9 and a lower pack box 9 ′ which provides a hydraulic fluid sealing arrangement, for preventing leakage under pressure thereof On the wall opposite to the disengage/engage indicator 6 / 6 ′, the clamp connector adapter housing 7 is provided with a landing indicator 13 , which indicates proper landing of the housing 7 on the clamp connector body 14 . The guide plates 12 enhance this landing process with precision. [0057] How the various features function is now explained with reference to the FIGS. 2 a , 2 b , 3 , 4 a , 4 b , 5 , 6 a , 6 b , 7 a and 7 b where like reference numerals represent like constructional features as detailed hereinbefore. [0058] The operation starts with the landing of the emergency tool on the clamp connector body 14 . This is effected by ROV (not shown). Incidentally, the ROV secures the emergency release tool 1 ′ in position during the operation and also effects the operation as now explained in detail. [0059] FIG. 2 a shows this position where the emergency release tool 1 ′ has landed on the clamp connector body 14 . The landing indicator 13 shown in FIG. 2 b , gives the indication for correct landing of the tool 1 ′ on the clamp connector body 14 by the ROV (not shown). The landing position in FIG. 2 a , is shown in detail in FIG. 2 b. [0060] The next step involves activating the piston 3 inside the cylinder 4 by actuating hydraulic means (not shown) so that the hole saw 11 is positioned co-axially to and around the jack screw 15 on the connector body 14 . The FIG. 3 in detail shows the indictor position 6 at this stage, which indicator helps in monitoring and effecting the operation. The FIG. 4 a illustrates this position of the hole saw 11 of the emergency release tool, around the jack screw 15 . The FIG. 4 b illustrates an enlarged portion of FIG. 4 a to precisely show this position. [0061] The position as detailed in the preceding paragraph is the precutting position. [0062] Now the hydraulic motor 1 is started and the drive of the hole saw 11 , i.e. rotation rod 10 starts rotating the hole saw 11 . The cylinder 5 is actuated hydraulically by release of hydraulic fluid in the cylinder 5 , so that the cylinder 4 with the piston rod 3 comes further down. This ensures that the hole saw 11 starts cutting down into the upper transversal block of the clamp connector 14 around the jack screw 15 and performs penetration. FIG. 5 a shows this stage. [0063] It can be seen from FIG. 5 a that the hole saw 11 has penetrated and been cutting through the clamp connector body 14 around the jack screw 15 , and also into and through the seal plate. The enlarged view in FIG. 5 b further clarifies this. [0064] The FIG. 6 shows the position 6 ′, as indicated by the indicator where the cutting operation is finished. This again facilitates perfect monitoring of the operation, to take a decision where the operation should end. At this stage (not shown in closer detail), the hole saw 11 has, as mentioned, penetrated the clamp connector body 14 and the seal plate, and around the jack screw 15 . By making the piston and cylinder 4 , 5 longer, it would be possible to penetrate into the lower block of the clamp connector body 14 around the jack screw 15 , actually all the way through if required. [0065] Now, the clamp connector 14 is totally released since the hole saw has cut the body around the jack screw 15 together with a thread portion of the block(s) of the clamp connector 14 . [0066] From this position, disengagement of the hole saw 11 is started. The hydraulic cylinders 4 , 5 are pressurized in the opposite direction to pull up the hole saw 11 and the indicator starts to move to disengaged position 6 , as shown in detail in FIG. 7 b . The operation now is just reverse of the one described above. [0067] When the indicator is at position 6 , the motor drive 1 is stopped and the emergency release tool is ready for upward removal from the clamp connector body 14 . Of course, the motor may be stopped immediately after the cutting operation is over, i.e. before the pulling up operation of the hole saw 11 . [0068] The gas compensator camera (not shown) helps avoiding large pressure inside the tool body, during operation. Emergency pressure release valve (not shown) may be deployed for this purpose as well. [0069] FIG. 7 a is a front view of the tool, side view whereof is shown in FIG. 2 a . This is again in the ideally disengaged position, as in FIG. 2 a . This is shown in closer detail in FIG. 7 b , as stated before, which is an enlarged view of the front portion of the clamp connector adapter housing 7 . This is the position shown as 6 by the position indicator. [0070] At this stage shown in FIG. 7 a , the tool may be removed from the top of the clamp connector body 14 by an ROV utilizing the handle 8 on the cylinder 5 . Once the emergency release tool 1 ′ is removed, the clamp connector 14 is disengaged since the jack screw 15 and the thread portion of the clamp connector 14 has become loose from the remainder of the clamp connector 14 . Due to the weight and hinged construction of the links 14 ′, the lower transversal block of the lower link 14 ′ will pull the jack screw 15 down from and through the upper block. [0071] Thus, emergency release of a sub sea clamp connector is facilitated by the tool of the present invention which is operable by an ROV. [0072] The emergency clamp connector release tool of the present invention and the method of applying it, as discussed hereinbefore is thus unique, hitherto unknown. [0073] From the foregoing description and also from the appended claims it would be clear to persons skilled in the art, that all the objectives of the present invention are achieved. [0074] The present invention has been described with reference to a preferred embodiment and drawings for the sake of understanding only and it should be clear to persons skilled in the art, that the present invention includes all legitimate modifications within the ambit of what has been described hereinbefore and claimed in the appended claims.

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CROSS-REFERENCE TO RELATED APPLICATIONS [0001] This application is a continuation-in-part of and claims priority in U.S. patent application Ser. No. 13/760,821, filed Feb. 6, 2013, now U.S. Pat. No. 9,026,106, issued May 5, 2015, which claims priority in U.S. Provisional Patent Application No. 61/595,536, filed Feb. 6, 2012, both of which are incorporated herein by reference. BACKGROUND OF THE INVENTION [0002] 1. Field of the Invention [0003] The present invention relates generally to satellite communication systems and, more particularly, to such a system which communicates from a communication hub to a remote station on one band and from the remote station to the hub on another band. [0004] 2. Description of the Related Art [0005] Modern telecommunication systems provide means for communicating vocal conversations, email, and various kinds of data from originating sources to destinations over twisted pair landlines, coaxial cables, fiber optic cables, and radio frequency communication links. Satellite communications have become an important mode of communications for large and small entities for both one-way services, such as television signals, and two-way services such as data processing services, satellite internet services, and the like. Two-way communication satellite services are typically set up as a head-end or hub station which is interfaced to a large scale communication network, such as the public switched telephone network (PSTN) infrastructure, and remote stations which communicate through a communication satellite to the hub station and through the hub station to the PSTN. The PSTN provides conventional telephone services and data communication over dedicated lines, the internet, and other links. Equipment for remote satellite stations has evolved to what is known as VSAT or very small aperture terminal satellite dishes. [0006] The present standard for VSAT satellite communications is the use of Ku band (12 to 18 GHz) satellite technology in order to use meter or sub-meter sized satellite antennas and to avoid costly licensing and frequency coordination. The problem with Ku band satellite technology is that it is highly susceptible to local rain or weather fade due to the nature of the frequencies used. For this reason, networks have to be tolerant of frequent signal fades or outages during the presence of rain, snow, and storm clouds. This occurs in all Ku band transmissions whether it is for residential satellite television or VSATs. [0007] Some networks attempt to mitigate the fade through the use of automatic uplink power control at the customer VSAT location. This technology gradually increases the transmit power at the remote customer location via a command from the hub location when the hub location senses that there is attenuation somewhere in the path between the remote location and the hub. This works some of the time quite well, but the same local weather anomaly that causes the problem with the inbound signal to the hub also creates a problem with the outbound power control signal to the remote site. Eventually, the control signal cannot reach the remote site electronics with sufficient strength and the remote site shuts down until it can receive a valid command. [0008] This is very bad for reliability and, as a result, Ku band networks are generally designed to be out of service for about 50 hours per year due to weather. For government and customer applications that need to know weather and other critical information, these 50 hours of down time cannot be tolerated. [0009] Heretofore there has not been available a dual-band satellite communications system with the features and elements of the present invention. SUMMARY OF THE INVENTION [0010] The present invention provides a hybrid satellite communication system in which a hub station transmits signals to remote stations through a satellite at a relatively low frequency which is unaffected by weather effects and in which the remote stations transmit signals to the hub station at a relatively higher frequency which enables the use of more economical equipment at the remote stations. The hub station senses the signal quality or strength received from each remote station and transmits power control signals to remote stations with poor signal strengths to cause such remote stations to increase their output power to overcome weather effects. The power control signals are transmitted on the lower frequency to prevent the power control signals from being masked by the weather effects. [0011] An embodiment of the present invention provides a technique to send the outbound signals from the hub at a much lower C band (4 to 8 GHz) frequency that is virtually unaffected by weather via the same satellite that is receiving a Ku band signal from the remote site. As a consequence, the remote site never or nearly never loses its control signal and is always changing its power in response to weather effects to thereby eliminate outages. This requires judicious selection of satellite transponders, special antennas, and specially designed feeds that allow simultaneous transmission of Ku band while receiving C band. [0012] An embodiment of the present invention provides a hybrid satellite antenna for the remote stations to enable the remote station to transmit and receive signals on different bands using a single antenna assembly. [0013] An embodiment of the present invention employs an offset feed/clear aperture antenna dish to enable the use of a reduced size dish without causing interference effects by receiving signals from or transmitting signals to multiple satellites. [0014] Various objects and advantages of the present invention will become apparent from the following description taken in conjunction with the accompanying drawings wherein are set forth, by way of illustration and example, certain embodiments of this invention. BRIEF DESCRIPTION OF THE DRAWINGS [0015] The drawings constitute a part of this specification and include exemplary embodiments of the present invention illustrating various objects and features thereof [0016] FIG. 1 is a diagrammatic view illustrating an embodiment of a hybrid C/Ku band satellite communication system. [0017] FIG. 2 is a block diagram illustrating components of an embodiment of the present invention. [0018] FIG. 3 is a side elevational view of an axial feed antenna dish which may be employed in an embodiment of the present invention. [0019] FIG. 4 is a side elevational view of an offset feed, clear aperture antenna dish which may be employed in an embodiment of the present invention. [0020] FIG. 5 is a schematic diagram of a hybrid C/Ku band satellite communication system comprising a first modified embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS I. Introduction and Environment [0021] As required, detailed aspects of the present invention are disclosed herein, however, it is to be understood that the disclosed aspects are merely exemplary of the invention, which may be embodied in various forms. Therefore, specific structural and functional details disclosed herein are not to be interpreted as limiting, but merely as a basis for the claims and as a representative basis for teaching one skilled in the art how to variously employ the present invention in virtually any appropriately detailed structure. [0022] Certain terminology will be used in the following description for convenience in reference only and will not be limiting. For example, up, down, front, back, right and left refer to the invention as orientated in the view being referred to. The words, “inwardly” and “outwardly” refer to directions toward and away from, respectively, the geometric center of the aspect being described and designated parts thereof. Forwardly and rearwardly are generally in reference to the direction of travel, if appropriate. Said terminology will include the words specifically mentioned, derivatives thereof and words of similar meaning II. Hybrid Dual-Band Satellite Communication System 1 [0023] Referring to the drawings in more detail, the reference numeral 1 generally designates an embodiment of a hybrid C/Ku band satellite communication system according to the present invention. The illustrated system 1 generally includes a satellite teleport facility or hub station 3 which communicates with a plurality of remote stations 5 by means of a geostationary communication satellite 7 . The hub station 3 is interfaced to a large scale communication network, such as the public switched telephone and data network (PSTN) 9 which provides telephone and data communication services. The remote stations 5 include communication devices, such as computers 12 and telephones 14 , which communicate with the PSTN 9 by way of the system 1 . [0024] Referring to FIGS. 1 and 2 , the illustrated hub station 3 includes a hub server 17 which is a processor or computer that controls the flow of data through the hub station 3 . The hub server 17 includes network interface circuitry 19 which interfaces the hub server 17 to the PSTN 9 . The illustrated hub station 3 includes a C band transmitter 21 which receives data from the hub server 17 and transmits the data through a C band antenna 23 to the satellite 7 on a C band frequency in the range of about 3.7 to 4.2 GHz. The hub station 3 includes a Ku band receiver 25 which receives data from a Ku band antenna 27 from the satellite 7 on a Ku band frequency in the range, as illustrated, of about 14 to 14.5 GHz. The transmitter 21 and receiver 25 are interfaced to the hub server 17 . [0025] Each remote station 5 includes a remote server 30 which is a processor or computer that controls the flow of data through the remote station 5 . The remote station 5 includes interface circuitry 32 to interface the remote server 30 to the computers 12 and telephone sets 14 communicating therewith. The illustrated remote server 30 outputs data to the satellite 7 through a Ku band transmitter 34 and a hybrid C/Ku band antenna 36 on the same Ku band frequency range as the hub receiver 25 and receives data from the satellite 7 through the hybrid antenna 36 through a C band receiver 38 on the same C band frequency range as the hub transmitter 21 . The use of the hybrid antenna 36 economizes the implementation of the remote station 5 as far as the purchase and mounting of an antenna and wiring therefor. [0026] The illustrated satellite 7 shown in FIG. 1 carries a plurality of C band and Ku band transponders (not shown). The transmission of signals from the hub station 3 and the satellite 7 on C band frequencies assures that such signals will reach the remote station 5 , since the C band range of frequencies are virtually immune to deterioration from weather effects. The hub server 17 monitors the signal quality of the Ku band signals received from the remote stations 5 . The output power of the remote Ku band transmitter 34 can be controlled by the remote server 30 to increase or decrease as needed to provide reliable signal quality from the remote station 5 to the satellite 7 and from there to the hub station 3 . The hub server 17 can control a remote server 30 to increase the output power of its transmitter 34 by an uplink power control UPC signal to overcome deterioration or fade of the signal from the remote station 5 due to weather effects. The UPC signal is sent at the C band frequency range to assure that it is received by the remote station 5 . [0027] A geostationary satellite 7 is a satellite which has an orbital period equal to the Earth's rotational period (one sidereal day), and thus appears motionless, at a fixed position in the sky, to ground observers. A geostationary orbit can only be achieved by locating a satellite at an altitude very close to 35,786 km (22,236 mi) above the surface of the earth and directly above the equator. Communications satellites and weather satellites are often given geostationary orbits so that the ground antennas that communicate with them do not have to move to track them, but can be pointed permanently at the position in the sky where they stay. Because of efforts to maximize the coverage of geostationary satellites, there tend to be clusters of closely spaced satellites positioned over the equator to serve national or continental areas, such as the North American continent from coast to coast. However, there is a limit to how closely satellites can be spaced to avoid interference issues when using economical sized antenna dishes on the ground. Currently, the minimum spacing is about two degrees of arc. [0028] Smaller sized dishes tend to be more economical than larger dishes and require less rugged mounting structure. However, smaller dishes have larger beam angles than larger dishes. The larger beam angle of a small dish may receive signals from two or more adjacent satellites and transmit signals to two or more satellites. The reception of signals from multiple sources either at the satellite or ground station may be interpreted as interference and cause undesired effects. [0029] Referring to FIG. 3 , a common type of dish for communicating with satellites is an axial feed dish 42 which has a feed assembly 44 located along the axis 46 of the dish 42 . Typically, the dish 42 is oriented to intersect the axis 46 thereof with the satellite with which it is intended to communicate. The axial feed dish 42 has no simple mechanism for avoiding transmitting to or receiving from multiple satellites if the size is reduced below a certain diameter. Thus an axial feed dish such as the dish 42 must be sized large enough to control its beam angle. [0030] Referring to FIG. 4 , an embodiment of the system 1 employs an offset feed/clear aperture dish 50 as the hybrid antenna 36 . The dish 50 has a feed assembly 52 located at an angle which is offset from the axis 54 thereof. The illustrated dish 50 is nominally a 2.4 meter dish and is appropriate for use on both C band and Ku band frequencies. The dish 50 is referred to as a clear aperture type dish because the offset feed assembly 52 does not block energy reflected from the dish surface, as can occur with an axial feed dish 42 . The dish 50 may be implemented as a 2.4 meter Model 1244 or 1251 dish manufactured by Prodelin Corporation (www.prodelin.com). Alternatively, other types of dishes may be used, such as the 3.8 meter Model 1383, also manufactured by Prodelin. The feed assembly 52 is a dual band feed assembly which is designed to receive in a C band frequency range and transmit in a Ku band range. The feed assembly 52 may be implemented as a Prodelin Model 0800-4487-1 or the like. The illustrated feed assembly 52 is supported by struts 56 and 58 in spaced and angled relation to the surface of the dish 50 to radiate radio frequency energy toward the dish 50 or to receive energy reflected from the dish 50 . [0031] Because the feed assembly 52 is angularly offset from the axis 54 , aiming of the dish 50 toward the satellite 7 is complicated somewhat, since the surface of the dish 50 must be angled in such a manner as to reflect the signal energy from the satellite toward the feed assembly 52 and from the feed assembly 52 toward the satellite. However, the offset feed dish 50 can be used to reduce the multiple satellite interference effect of the beamwidth thereof, such that a smaller size dish can be used than would otherwise be possible. [0032] While the system 1 has been described using C band frequencies from the hub station 3 to the remote stations 5 and Ku band frequencies from the remote stations 5 back to the hub 3 , it is foreseen that other sets of bands could be employed, such as Ka band frequencies (26.5 to 40 GHz) from the remote stations 5 to the hub station 3 . [0033] FIG. 5 shows a hybrid, dual-band satellite communication system 101 comprising a first modified embodiment of the present invention. The system 101 can operate at any suitable frequencies, including C and Ku band frequencies. Without limitation, examples of extended frequency ranges for different models of block up converters (BUCs) and low-noise block converters (LNBs) for the system 101 are as follows: [0000] TABLE 1 Ku-Band Variations Transmit Frequency Receive Frequency (GHz) (GHz) Extended Ku-Band 13.25-14.5 10.95-12.75 [0000] TABLE 2 C-Band Variations Transmit Frequency Receive Frequency (GHz) (GHz) Extended C-Band 5.850-6.725 3.400-4.800 [0034] Moreover, the antennas can comprise 3.8 m Prodelin antennas, e.g. Model No. 1241 and Model No. 1385. A variety of other antenna sizes and configurations can be used with the systems of the present invention. Without limitation, typical antenna dish sizes can range from about 1.5 m to about 4.6 m. The systems of the present invention can use a separate Ku band uplink with a C band downlink. [0035] It is to be understood that the invention can be embodied in various forms, and is not to be limited to the examples discussed above. The range of components and configurations which can be utilized in the practice of the present invention is virtually unlimited.

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RELATED APPLICATION [0001] This application claims priority to Provisional Patent Application Ser. No. 62/257,897, filed Nov. 20, 2015, the disclosure of which is incorporated herein by reference. FIELD OF THE INVENTION [0002] This invention relates generally to the utilization of phase change materials in buildings to reduce energy consumption and lower energy costs for the cooling and heating of the buildings and more particularly to such a system utilizing bio-based phase change materials encapsulated in plastic layers having heat transfer capabilities. BACKGROUND OF THE INVENTION [0003] The utilization of phase change materials within a building to enhance the thermal performance of a building is well known. Phase change material is a highly productive thermal storage medium which can be utilized through the change of its physical state within a certain temperature range to mitigate the amount of energy consumed in maintaining the temperature of a building structure. When the temperature of the phase change material is obtained which causes it to transition from a solid to a liquid state, the phase change material absorbs and stores a large amount of latent heat. When the temperature of the phase change material then passes so that the material goes from a liquid to a solid state, the stored latent heat is released into the environment. The thermal effects which are obtained by utilizing a phase change material within a building structure is a cooling effect caused by the latent heat absorption of the phase change material, a heating effect caused by the latent heat release of the phase change material. This provides a regulating effect of the temperature within the building from either latent heat absorption or latent heat release of the phase change material. [0004] It is, therefore, desirable to provide a phase change material of a specific type and constructed in a specific manner which enhances the reduction of the energy consumption within a building adapted for human habitation. SUMMARY OF THE INVENTION [0005] A system for energy consumption savings and cost reduction in structures adapted for human habitation which includes a building having a room including a ceiling and having a plenum area above the ceiling, a first mat including a phase change material encapsulated within layers of plastic material having heat transfer capability disposed in the plenum area, a second mat including phase change material encapsulated within layers of plastic material also having heat transfer capability disposed within the plenum area but spaced from the first mat. The amount of phase change material contained within each mat being between 0.15 lbs. and 1.0 lbs. per square foot and the solid to liquid transition point for said phase change material is from 72° F. to 76° F. and the liquid to solid transition point for said phase change material is from 71° F. to 68° F. BRIEF DESCRIPTION OF THE DRAWINGS [0006] FIG. 1A is a perspective view of a mat containing phase change material constructed in accordance with the principles of the present invention; [0007] FIG. 1B is a side view of the structure illustrated in FIG. 1A ; [0008] FIG. 2A is a perspective view of a typical assembly of the structures illustrated in FIG. 1A for installation in a plenum area; [0009] FIG. 2B is a side view of the structure as shown in FIG. 2A ; [0010] FIG. 3A is a perspective view illustrating an assembly of the type shown in FIG. 1A installed on the underside of a ceiling in a structure; [0011] FIG. 3B is a side view of the structure as shown in FIG. 3A ; [0012] FIG. 4A is a perspective view illustrating an assembly wherein more than one mat is installed in the plenum area of a structure; [0013] FIG. 4B is a side view of the structure as shown in FIG. 4A ; [0014] FIG. 5A is a perspective view illustrating an assembly wherein a plurality of mats are disposed within a plenum area above the upper surface of the ceiling; [0015] FIG. 5B is a side view of the structure as shown in FIG. 5A ; [0016] FIG. 6A is a perspective view of an assembly positioned directly on top of a perforated ceiling or ceiling tile materials in lieu of typical ceilings or ceiling tiles; [0017] FIG. 6B is a side view of the structure illustrated in FIG. 6A ; [0018] FIG. 7A illustrates a side view of mats containing phase change material as shown in FIG. 1 disposed in a vertical position within a plenum and with the mats equally spaced; [0019] FIG. 7B is similar to FIG. 7A but with the mats positioned at different heights and different spacings; [0020] FIG. 8A is a perspective view of an assembly such as that shown in FIG. 1A installed vertically against the wall in the plenum space; and [0021] FIG. 8B is a side view of a structure of FIG. 8A , but further including insulation materials. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS [0022] The inventors have developed organic and inorganic phase change material (PCM) applications which are engineered to significantly reduce energy consumption and lower energy costs for the cooling and heating of residential and non-residential buildings. While PCMs have been used and tested as thermal mass components in buildings for at least 40 years, the engineering and adoption of PCMs into the marketplace has been hampered by lack of valid and accurate engineered solutions to support effective designs and installations of high performance PCM assemblies. The challenge has been to develop PCM assemblies that accomplish significant energy and cost savings while at the same time meeting reasonable economic models for an acceptable Return on Investment (ROI) and First Cost. Numerous studies show that PCMs can reduce energy consumption by reducing and shifting peak energy use loads yet there is little market penetration due to poor performance and long ROI's for existing PCM products. This is largely due to the lack of engineering, technical development and performance optimization of the PCM product assemblies themselves. [0023] The inventors have developed practical and economical PCM applications for new and existing buildings comprised of various phase change materials (PCM) called StasisPCM, which are assemblies consisting of bulk PCMs, various containment options for packaging, and various engineering and installation methods which, when combined or used individually, cause the PCM assemblies to store energy (heat) by undergoing a solid-to-liquid phase transition, the melting point, and release energy by undergoing a liquid-to-solid phase change, the freezing point, at specific, engineered temperatures. StasisPCM utilizes optimized engineering of the bulk PCM combined with enhanced packaging and installation to create PCM assemblies which yield significantly greater energy savings and shorter ROI than any other PCM product available in the marketplace. StasisPCM can be installed in new or existing residential or commercial buildings in the space above ceilings or ceiling tiles and between floors in multi-story buildings or below the roof in single story buildings or in conjunction with metal roofs like the standing seams roof. StasisPCM mitigates and manages the thermal energy in these areas, whether caused separately or in combination by internally generated (occupant, lights and equipment) loads, or by external loads (caused by solar gain from the sun and thermal gain due to the ambient, outside air temperature.) StasisPCM assemblies can be installed in one or more layers, over complete building areas or part of the building areas, and are part of an engineered solution designed to reduce energy consumption due to heating and cooling and to reduce costs and create energy savings. [0024] Bulk PCMs are readily available both domestically and internationally and generally are separated into three major categories, differentiated by their active materials: organic, inorganic and bio-based. [0025] Organic PCMs are petroleum based and most commonly derived from paraffinic compounds. They are chemically stable and melt congruently, however they are flammable, can generate harmful fumes on combustion, have generally lower latent heat capacities and usually are microencapsulated with compounds such as acrylic to decrease flammability but this process often insulates the PCM and decreases effectiveness of the product. [0026] Inorganic PCMs are salt hydrates or eutectic salts or similar compounds which typically have a high latent heat capacity, generally non-flammable and relatively inexpensive but can be highly corrosive and exhibit a high level of instability, erratic re-solidification and suffer from cycle degradation which shortens life cycle and yields poor performance. [0027] Bio-based PCMs are the newest type of PCMs and have evolved due to the above mentioned disadvantages of the Organic and Inorganic compositions. They are primarily naturally occurring fatty acid compounds, such as natural palm, date and coconut oils, but can also be beef tallow and certain types of algae. They possess high latent storage capacities, show no performance degradation due to cycling and their flammability and combustibility levels are suitable for construction products and with proper containment or packaging pass flame and fire test standards required for commercial grade building materials. [0028] There are also a few hybrid PCM compounds available which are generally derived by mixing two or more PCMs together but these are generally marginal products that have not been scientifically developed or supported by technical research. [0029] The inventors use bio-based PCM as the primary type of bulk PCM for their assemblies. High latent heat capacities, stable compounds, low flammability, extended life cycle and no degradation of performance over time are critical to developing a long lasting and high performance product. Through rigorous experimentation and testing of our PCM assemblies, the inventors have determined the variables affecting the performance of PCMs installed in a building space, and which must be considered when engineering a PCM solution: [0030] The building and the HVAC system must be analyzed, and variables such as internal loads (from occupants, lighting and equipment), external loads (from solar heat gain and ambient air affects), schedule of occupancy, systems controls, Building Automation Systems, plenum air velocities and temperatures, thermostat set points, geographic location, physical orientation of building, type of building construction, building thermal resistance, amount of glass in combination with the amount and type of envelope building materials covering the building exterior, must be identified and evaluated in order to design a high performance engineered PCM solution. [0031] The PCM must be optimized for latent heat storage capacity over specific melting and freezing temperature ranges that are necessary for optimized PCM performance for specific building temperatures, territories and operational profiles. The bulk PCM assemblies and specific melting and freezing properties may also be optimized for specific climate zones. [0032] The actual amount of bulk PCM selected for an installation is determined by the needs of the client and building owner. In some cases the ROI drives product selection and in others the amount of energy reduction is the determining factor. [0033] The amount of bulk PCM installed per square foot of packaging can vary from 0.15 lb/sf up to 1.0 lb/sf, depending upon design requirements. The amount per SF of bulk PCM is optimized by determining the total thermal load affecting the specific building installation, whether internal, external or comprised of both, measured in BTU/SF/HR, and analyzing the total loads as they occur over a 24 hour period, paying particular attention to the hours of building occupancy and use, using proprietary PCM design software. Once the specific magnitude and occurrence of the thermal load targeted for mitigation is identified, then the appropriate bulk PCM formulation is selected to provide the best performance based upon the unique temperature profile of the bulk PCM, so that the melting and freezing ranges of the PCM selected occurs within the normal temperatures encountered within the building assembly. Once the specific bulk PCM formulation is selected, then the joules/gram of latent heat capacity is known (as each temperature formulation has a different j/g latent heat value) and the amount of material used per square foot is determined by using enough bulk PCM per square foot to counteract the amount of total thermal load targeted for mitigation. This process yields a PCM assembly that is specifically engineered for volume, weight, latent heat capacity and temperature profile to offset the thermal loads by capturing a specific amount of BTUs over a specific time period. [0034] For example, for an internal zone of a multi-story office building in any climate zone, where the PCM assembly is installed in the space between the top of ceiling or ceiling tile and the bottom of the floor above (the plenum area), and the space is subject to a thermal load due to lights, equipment and occupants, of 8 BTU/SF/HR and the space is occupied for 11 hours per day, then the total load over the 11 hours is 88 BTU/SF of thermal energy introduced into the space. Using a bulk PCM that has been selected for the appropriate temperature melt and freeze ranges (in this example, a melt range from 76° to 72° F. and a freeze range from 71° to 68° F., with a latent heat value of 192 j/g), a PCM assembly containing 0.5 lb to 0.67 lb/SF may be selected. The melting temperature range of the bulk PCM is selected due to the fact that this range of melting temperatures corresponds very closely to the occupied space temps controlled by the HVAC system and thermostat set points, and the freezing temp range is selected because it is lower temperature than the melting range and also can be easily reached by typical HVAC cooling systems or by using “free” economizer cooling if cool nighttime temperatures below 68° F. are common for the specific climate zone. In this example, the 0.5 lb/SF package has 42 total BTU/SF of latent heat storage capacity and the 0.67 lb/SF has 55 BTU/SF. Depending upon the actual cost per KWh of electricity charged by the utility company, and whether or not peak pricing energy rates in effect, the PCM assembly yielding the most advantageous energy savings is selected and placed directly on top of the ceiling or ceiling tile in the interior offices. (It should be noted that if even greater energy savings is desired, then more than one layer of PCM assembly may be installed using the techniques and methods described below to suspend more than one layer of PCT). [0035] For an external zone of a multi-story office building in the Los Angeles climate zone (specifically Burbank, Calif.), where the PCM assembly is installed in the space between the top of ceiling or ceiling tile and the bottom of the floor above, in the South and West perimeter rooms (adjacent to the building exterior), and the space is subject to an internal thermal load due to lights, equipment and occupants, of 88 BTU/SF/over the occupied hours, and a combined external solar gain and ambient thermal load gain over the same period of 180 BTU/SF, then the total thermal load is 268 BTU/SF, however this load is not uniform and increases in magnitude over the 11 hour period of occupied use. Using a bulk PCM that has been selected for the appropriate temperature melt and freeze ranges (in this example, a melt range from 76° to 72° F. and a freeze range from 71° to 68° F. which has a latent heat value of 192 j/g), PCM assemblies containing 0.5 lb to 0.67 lb/SF may be selected. In this example, the 0.5 lb/SF package has 42 total BTU/SF of latent heat storage capacity and the 0.67 lb/SF has 55 BTU/SF. In this example for Burbank, Calif., the utility company offers peak and off peak pricing for energy, so the strategy is to “shift” as much of the energy use to off-peak, nighttime hours. In this example, this can best be accomplished by installing the PCM assemblies in combination to yield the most advantageous energy savings. A PCM package containing 0.5 lb/SF of bulk PCM is installed directly on top of the ceiling or ceiling tile and one or more 0.67 lb/SF PCM packages are installed elevated in the space above the first PCM package, using techniques and methods described below. Elevated PCM packages are installed at varying heights, varying from 4″ to 12″ above the first package. One 0.67 lb/SF PCM package is installed above the first package if the shortest ROI is desired, and two or more packages are installed if the client desires the maximum energy savings over shortest ROI. [0036] This same building, for the North and East facing exterior zone perimeter offices, the total magnitude of combined thermal load is less than for West and South facing offices. In this example, the total internal load is 88 BTU/SF and the total external load is 100 BTU/SF for a total load of 188 BTU/SF, which increases in magnitude over the period of occupancy. In this example for Burbank, Calif., the best performing PCM assembly ROI is to install 0.67 LB/sf of bulk PCM directly on top of the ceiling or ceiling tile, in the same temp and latent heat capacities described above, or can be modified to include an elevated package of bulk PCM is maximum energy savings is desired. [0037] Using the strategies for engineering and savings described above to design and install PCM assemblies, this example of a Burbank, Calif. multi-story building can yield energy consumption savings related to cooling from 25-45% and cost reductions from 40-55% related to cooling, annually, dependent upon the final result desired by the client. [0038] Similar engineering solutions can be applied for other buildings in other climate zones throughout the country, where all of the unique factors affecting energy usage are determined and then the most appropriate and highest performing PCM assembly is deployed. [0039] The PCM assemblies may also be optimized to completely or partially capture and shift daytime energy use load to low-use or low-demand, off peak hours, as established by the utility company or power providers. [0040] The packaging or assembly of the bulk PCM must also be engineered to optimize the performance of PCM, specifically related to maintaining high surface area to volume ratios and overall size and shape of the PCM packaging, as these factors dramatically affect PCM performance. [0041] The physical properties and composition of the packaging material are also designed and selected based upon the specific thermodynamic conditions and heat transfer mechanisms governing the specific installation and intended use, whether the heat transfer is conductive, convective or radiant. [0042] The overall size of PCM assemblies are manufactured as follow: 1 ft×2 ft, 1 ft×4 ft, 2 ft×2 ft, 2 ft×4 ft. These sizes are the most suitable for installation above ceiling or ceiling tiles and generally mirror the overall dimensions of commercial ceiling tiles. For some applications, particularly when the assemblies are installed vertically, as in a wall cavity, the overall length of the PCM assemblies are manufactured in lengths as required for ease of installation. [0043] In some cases the PCM is optimized to incorporate “free economizer cooling”, provided by cool, nighttime ambient, outside air, available in some climate zones during certain parts of the year, where it is possible to use “free”, outside ambient air to freeze the PCM assemblies during the night time in lieu of mechanically conditioned air. [0044] For the interior zone of multi-story commercial office buildings, (central core space which is buffered by offices exposed to the building exterior and typically not affected by external thermal loads), the ideal bulk PCM melting point range is from 72 to 76° F. and the freezing point range is from 71 to 68° F. [0045] For the exterior zones of all buildings, the ideal bulk PCM melting and freezing point ranges may vary and are determined by performing an engineering analysis of the building variables and climate zone in order to optimize PCM assembly performance. [0046] For multi-story commercial office buildings, in certain territories, the use of “free” economizer cooling can be utilized and combined with various PCM assemblies to yield dramatic reductions in energy consumption and energy cost. [0047] In some cases the StasisPCM is placed directly on top of the ceiling or installed above the ceiling tile and the packaging is selected for optimized heat transfer determined by the location and method of installation. [0048] In all cases, the packaging material selected for the top and bottom faces of the PCM assembly are multi-layer films with unique compositions, where the top film and the bottom film are sealed using heat and in some cases adhesives, that are engineered for the specific PCM installation. [0049] For most of our PCM assemblies, we use a multi-layer film composed of individual layers, bonded together, of Nylon, Adhesive, Polyethylene Tie EVOH barrier and Tie Polyethylene sealant for exposed surfaces of packaging and add titanium dioxide to the side bearing on the ceiling tile or ceiling. Aluminum may also be added to one or both faces of packaging for assemblies required to meet fire test standards. [0050] If the PCM package is in physical contact with the ceiling or ceiling tile below, the contact surface may be selected to optimize conductive heat transfer, and the exposed surface of the package may be optimized for convective air transfer, induced by air circulating within the plenum area above the ceiling or tile. [0051] In some cases, the top and bottom (exterior faces) of the PCM assembly may be designed to retard convective and or conductive heat transfer. [0052] In some cases, the top and bottom of the PCM assembly may be designed using reflective or radiative facings. [0053] In some cases, more than one layer or level of PCM assemblies are installed and separated from adjacent assemblies, either vertically or horizontally, by providing space between individual layers or levels by utilizing the a grid to install more than one PCM package or assembly and can increase the convective heat transfer between layers or levels of PCM and increases the total latent heat storage capacity of the PCM installation. [0054] Individual levels or layers of PCM may be the same temperature profile or may be of different temperature profiles, may be of same or different packaging, depending on the engineering of the application. [0055] The ability to install more than one PCM assembly in the vertical space above a ceiling tile or ceiling is key to optimizing and increasing StasisPCM performance, whether the multiples of PCM assemblies are manufactured or field assembled, whether they are of the same packaging or different, on one or both faces, whether the PCM is installed as separate elements or as part of a single or multi-part assembly, whether the bulk PCM in any given package is of identical formulation or whether they are different formulations for temperature, latent heat storage potential and or melt and freeze ranges. [0056] The method of installing one or more PCM assemblies may be accomplished by supporting the PCM directly on top of the ceiling or ceiling tile or by utilizing the ceiling tile grid work for support or by suspension from the framing members above the ceiling or ceiling tile, by use of racks, trays or cassettes wherein more than one mat or package is installed either horizontally or vertically separated from the adjacent package, either beside or below. [0057] Multiple PCM assemblies, racks, trays, called the StasisGRID system, or other multiple package assemblies may also be supported by wires, structural elements attached to building sub framing located above the ceiling or ceiling tile, or may be suspended by wires, mesh or grids hung vertically or horizontally throughout the space above the ceiling or ceiling tile. [0058] In some cases, the plurality of mats, assemblies or packages may be installed attached to or adjacent to the underside of framing above the ceiling or ceiling tile, whether the framing is a subfloor or underside of roof construction element. [0059] By using individually or by combining one or more of the methods above, additional latent heat storage capacity can be increased to significantly reduce energy consumption, shift the energy demand load to off-peak usage, and reduce the cost of energy used for heating and cooling. [0060] Use of PCM assemblies also results in increased life expectancies of HVAC units and reduced maintenance costs of the equipment. [0061] Other PCM assemblies which reduce energy consumption and energy costs include: Combining the PCM assemblies with metal ceiling tiles or panels which can also be perforated, by replacing or installing the metal in lieu of ceiling tiles. Combining the PCM assemblies with “egg crate” ceiling tiles or lighting panels, whether made of plastic, metal, PVC, foam or wood, by replacing or installing the “egg cate” in lieu of ceiling tiles. Combining PCM assemblies with one or more layers of building insulation, whether on one or both sides, to manage and affect the flow of thermal energy through the PCM by inhibiting the release of thermal energy from one side of the assembly. Combining the bulk PCM with metal or composite additives to enhance thermal conductivity and heat transfer within the PCM assembly. Combining the bulk PCM with metal or composite inserts, located within the packaging and surrounded by bulk PCM, which increase thermal conductivity and heat transfer throughout the PCM assembly. Combining the PCM assemblies with metal roof or wall panels for new and retrofit applications, where building insulation is installed between metal panels and PCM assemblies to increase thermal resistance or R-value of the overall assembly. [0068] One of the additional challenges faced by PCM product companies to successfully introduce their PCM products to the marketplace has been the lack of accurate, validated design and engineering software suitable to creating an optimized and high performance PCM design for new or existing residential or commercial buildings. Current software products do not accurately predict the performance of PCM assemblies for many different reasons. The inventors have developed engineering, design, estimating and optimization software for PCMs in numerous construction applications, including new designs and retrofit applications for existing building. [0069] The software developed by the inventors incorporates numerous proprietary algorithms which have been developed as a result of rigorous testing and experimentation of their PCM assemblies in lab, small scale and full scale test installations. The software may be used for existing (retrofit) applications, for new construction projects or designs and for evaluating the potential downsizing of the HVAC system capacity due to use of PCMs. This software is capable of designing, engineering and estimating PCM applications and optimizes for performance and cost. [0070] The software is an engineering software product that performs analysis and design of PCM applications for both new and retrofit construction. [0071] The software has unique input variables for: [0072] Latent heat capacity of the bulk PCM formulation used; [0073] Specific Melt Temperature Range; [0074] Specific Freeze Temperature Range; [0075] Physical Properties of the top and bottom and sides of the containment system used, including specific heat, specific gravity, heat transfer coefficients, thermal insulating of materials used, heat flux and related variables for conduction and convective heat transfer mechanisms; [0076] Analysis of more than one melt and freeze point within the same formulation; [0077] Evaluation of the effects of self-insulation and sub cooling on the bulk PCM; [0078] Analysis and optimization of the PCM assembly for specific engineering solution and installation of the PCM assembly, including determining performance based upon the specific ΔT (delta T) and time over which the PCM is intended to perform. [0079] The software also has the ability to generate data interface and data transfer files to communicate with the most commonly used Energy Modeling Software products available in the marketplace. [0080] FIG. 1A and FIG. 1B illustrate a typical manufactured assembly of PCM in a pouch or sachet based package, where each pouch or sachet is filled with a specific amount of bulk PCM, inserted into the packaging while the PCM is in liquid state. The configuration shown contains 56 individual pouches or sachets, evenly spaced, over a 1 ft×2 ft PCM assembly. The individual pouches or sachets ( 1 . 2 ) are sized to contain specific amounts of bulk pcm ( 1 . 1 ) and will vary dependent upon PCM volume but will maintain maximize surface area of packaging while observing the maximum depths of the pouches or sachets, as too much volume of bulk PCM inhibits the performance of the PCM assembly. Quantity of pouches or sachets will also vary according to quantity of bulk PCM required by design per each square foot of package or PCM assembly. In some cases, the PCM assembly will consist of larger packages, pouches, pans, trays, slabs or other assemblies to contain the bulk PCM in an assembly intended to be installed above the ceiling or ceiling tile and below the floor above or roof framing above. The PCM assembly is installed over ceilings or ceiling tiles and the overall dimensions of the packaging may vary to accommodate different sizes of ceiling tiles. The PCM packaging shown consists of two multi-layered films, the top layer ( 1 . 3 ) and the bottom layer ( 1 . 4 ), which are sealed together ( 1 . 5 ) at predetermined points to create pouches or sachets. Individual pouches or sachets of PCM are separated by joints ( 1 . 6 ) which may be heat seals or heat seals combined with adhesive sealants to create individual pouches. The materials top and bottom layers of films may be the same or may be of different compositions, and are optimized for conductive heat transfer, convective heat transfer, depending upon use and design of the PCM assembly. In some cases reflective and radiant facings may be selected as required by design. In certain applications the multi-layered films used for PCM packaging are designed to be fire resistive and to meet or exceed the ASTM E 84, UL 723 or NFPA 255 fire test procedures. [0081] FIG. 2A and FIG. 2B illustrate a typical PCM assembly installation, where the PCM Assembly ( 2 . 1 ) is placed directly on top of the ceiling or the ceiling tile ( 2 . 2 ), which is itself supported by ceiling tile grid or bar support systems ( 2 . 2 ) and suspended by support wires or other attachments ( 2 . 4 ) which are attached to the upper framing materials above. The individual faces of the PCM packaging material itself may be selected to optimize heat transfer where the face of packaging in contact with the ceiling or ceiling tile is optimized for conductive and the face of exposed packaging above optimized for convective heat transfer. In all cases, one or both faces of the PCM assembly ( 2 . 1 ) may be comprised of special multi-layer facings which are specifically designed and selected based upon their unique heat transfer properties in addition to their ability to meet or exceed fire and smoke test standards, as required by design. [0082] FIG. 3A and FIG. 3B illustrate a typical PCM assembly installation where the PCM assembly ( 3 . 6 ) is placed directly under and adjacent to the underside of roof or floor framing ( 3 . 1 ) and held in place by fasteners ( 3 . 2 ) attaching the PCM assembly directly to the floor or roof structure or can be held in place by duct pins, wind lock washers, wires, racks, grids or other methods of attachments designed to hold the PCM assembly snug to the underside of roof or floor framing to enhance conductive heat transfer between the underside of roof or floor and the PCM assembly. Roof framing materials may be steel, concrete, wood, masonry or other common construction materials. In some cases the upper face of PCM assembly may be installed using the methods of attachment shown but with an air gap between the upper face of PCM assembly and the underside of floor or roof framing, as required by design, and where the upper surface of PCM packaging ( 3 . 3 ) may be optimized for convective heat transfer (not shown). The bottom side of the PCM assembly packaging ( 3 . 4 ) may also selected to increase the thermal efficiency of the PCM assembly, specifically for convective heat transfer, when the lower face of packaging is exposed (detail not shown). In some cases the bottom of the PCM assembly may be covered by a layer of insulating material ( 3 . 5 ) to retard thermal energy transfer through the bottom face of the PCM assembly packaging, in which instance the packaging materials composition is selected for a low rate of conductive heat transfer through the PCM assembly surface in contact with the insulation. [0083] FIG. 4A and FIG. 4B illustrate a typical PCM assembly installation, where more than one PCM assembly is installed in the building space between top of ceiling and underside of roof or floor framing above. The first PCM assembly ( 4 . 1 ) is placed directly on top of a ceiling or ceiling tile ( 4 . 2 ), which is itself supported by ceiling tile grid or bar support systems ( 4 . 3 ) and suspended by support wires or other attachments ( 4 . 4 ) which are attached to the upper framing materials above. In some cases the first PCM assembly may be installed directly adjacent to the underside of the floor or roof framing above. The second PCM assembly ( 4 . 7 ) is installed on top of or supported by an elevated support system ( 4 . 5 ) that raises the PCM assembly above the upper surface of the ceiling or the ceiling tile ( 4 . 2 ). The elevated support system as shown ( 4 . 6 ) is bearing directly upon the top of the ceiling tile or ceiling, but may also be supported independently from the ceiling or tile by bearing on the ceiling tile support grid work or T-Bar system, or may be suspended from underside of roof or floor framing above using racks, wires, brackets, trays, baskets or other support members to suspend the PCM assembly above the surface of the ceiling tile or ceiling or below the underside of floor or roof framing and expose both surfaces of the PCM assembly to convective heat transfer. The PCM assembly packaging films may be selected to improve convective heat transfer between the PCM assembly and the surrounding air or to optimize thermal energy transfer between adjacent PCM assemblies. The measurement between the PCM assemblies themselves and the measurement between the PCM assemblies and the ceiling or ceiling tile below, or the roof or floor framing above, is determined by engineering for the best placement of PCM assemblies based upon unique building variables for best performance. In some cases the raised PCM assemblies may be installed at different heights or may be installed at the same heights. In some cases the PCM assembly placed adjacent to the top of ceiling or ceiling tile or against the underside of floor or roof framing may be omitted, and only raised or suspended PCM assemblies subject to convective heat transfer on both exposed surfaces are installed. The thermal performance, freeze and melt ranges, and latent heat capacity of the bulk PCM contained in each assembly can be either the same or different, depending upon design and performance requirements. [0084] FIG. 5A and FIG. 5B illustrate a typical multiple package PCM assembly installation, where more than one PCM Assembly ( 5 . 1 , 5 . 2 ) is placed directly on top of an elevated support systems ( 5 . 3 , 5 . 4 ) that raise the PCM assembly above the upper surface of the ceiling or the ceiling tile ( 5 . 5 ), which is itself supported by ceiling tile grid or bar support systems ( 5 . 6 ) and suspended by support wires or other attachments ( 5 . 7 ) which are attached to the upper framing materials above. The elevated support system as shown ( 5 . 3 ) is bearing directly upon the top of the ceiling tile or ceiling ( 5 . 8 ), but may also be supported independently from the tile by bearing on the ceiling tile support grid work or T-Bar system, or may be suspended from above using racks, wires, brackets, trays, or other support members ( 5 . 4 ) to elevate additional PCM assemblies ( 5 . 1 , 5 . 2 ) above the surface of the ceiling tile or ceiling or below roof or floor framing above and expose both surfaces of the PCM assembly to convective heat transfer. In some cases multiple PCM assemblies may be installed to create a multi-layer of PCM assemblies, as required by design. The PCM assembly packaging material may be selected to improve convective heat transfer between the PCM assembly and the surrounding air and between adjacent PCM assemblies. In some cases the PCM packaging may be the same on both exposed faces or may be different within one package assembly and between one or more package assemblies. The measurement between the PCM assembly and the top of ceiling or ceiling tile below or the bottom of roof or floor framing above is determined by engineering for the best placement of PCM assemblies for best performance. In some cases, the elevation of the raised PCM assemblies may vary or may be of the same elevation. In some cases the PCM assembly may also be installed bearing either on top of the ceiling or ceiling tile or attached to the underside of roof or floor framing above (not shown) in addition to the suspended PCM assembly or assemblies. The thermal performance, freeze and melt ranges, and latent heat capacity of the bulk PCM contained in each assembly can be either the same or different, depending upon design and performance requirements. [0085] FIG. 6A and FIG. 6B illustrate a typical installation of a PCM assembly directly on top of perforated ceiling or ceiling tile materials in lieu of typical ceilings or ceiling tiles. Perforated ceiling materials or ceiling tiles ( 6 . 1 ) may be used in combination with any of the above methods previously described above. Perforation or otherwise removing material from the element separating the PCM assembly and the space below the ceiling or ceiling tile increases the rate and transfer of thermal energy into the PCM assembly ( 6 . 4 ) by reducing thermal resistance and increases the performance of the PCM assembly. Using a perforated material, such as a perforated metal grid or panel, egg crate, lighting grills or other materials which may be metal, plastic, wood or foam, allows for faster melting and freezing rates of the bulk PCM which can increase overall PCM assembly performance. Perforated assemblies are typically installed into standard ceiling tile support systems ( 6 . 2 ) and supported by attachment to framing above ( 6 . 3 ) but in some cases replace the support systems in their entirety or just partially over the occupied space below. More than one PCM assembly can be installed in the space above the perforated ceiling or ceiling tile and below the underside of floor or roof framing by using methods previously described. Bulk PCM formulations and performance and PCM assembly packaging can also be designed and installed as previously described. In all cases, one or both faces of the PCM assembly may be comprised of special multi-layer facings which are specifically designed and selected based upon their unique heat transfer properties in addition to their ability to meet or exceed fire and smoke test standards, as required by design. [0086] FIG. 7A and FIG. 7B illustrate a typical installation of one or more PCM assemblies installed in a vertical or upright orientation in the space between the top of ceiling or ceiling tile and below the underside of floor or roof framing. Vertical PCM assemblies ( 7 . 1 ) can be attached to upper framing ( 7 . 2 ) by fasteners, brackets or held in place by grids, cassettes, wires ( 7 . 3 ) or hangars or in some cases be supported by ceiling mounted assemblies that bear on the ceiling and allow the PCM assemblies to hang or drape vertically from or over framing (not shown). The PCM assemblies can be installed at the same height or distance from ceiling below ( 7 . 4 ) or roof above ( 7 . 5 ) or they can be installed at alternating or different heights or distance from ceiling below ( 7 . 6 , 7 . 12 ) and roof above ( 7 . 7 ), depending upon design. The measurement between PCM assemblies ( 7 . 8 ) can also be varied per design requirements. In some cases multiple PCM assemblies may be installed to create a multi-curtain of PCM assemblies. In some cases horizontal PCM assemblies (not shown) may also be installed on top of the ceiling or ceiling tile ( 7 . 9 ), which is supported by ceiling or ceiling tile framing ( 7 . 10 ) and hung from the underside of floor or roof framing above ( 7 . 11 ). The PCM assembly packaging material may be selected to improve convective heat transfer between the PCM assembly and the surrounding air and in some cases the PCM packaging may be the same on exposed both sides or may be different within one package assembly and between one or more package assemblies. The orientation of the PCM assemblies may be altered to increase or decrease the convective heat transfer between the vertical PCM assemblies and the direction of the air flow in the space between the ceiling below and the framing above, whether such orientation is parallel, perpendicular or some angle in between, relative to the direction of the air movement. The thermal performance, freeze and melt ranges, and latent heat capacity of the bulk PCM contained in each assembly can be either the same or different, depending upon design and performance requirements. In all cases, one or both faces of the PCM assembly may be comprised of special multi-layer facings which are specifically designed and selected based upon their unique heat transfer properties in addition to their ability to meet or exceed fire and smoke test standards, as required by design. [0087] FIG. 8A and FIG. 8B illustrate a typical installation of a PCM assembly installed vertically against the wall or walls in the attic or plenum space between the top of ceiling or ceiling tile and the underside of floor or roof framing above. The PCM assembly ( 8 . 1 ) is attached on the inside of wall framing ( 8 . 2 ) by fasteners ( 8 . 3 ), brackets, tabs, wires or other installation materials. Where the face of PCM assembly package is in contact with the inside face of wall framing ( 8 . 4 ), the packaging material may be optimized for conductive heat transfer between wall materials and PCM assembly. In some cases there is an air gap between the face of wall framing and the face of PCM packaging (not shown). The outside face of the PCM packaging ( 8 . 5 ) may be installed against insulation materials ( 8 . 6 ) attached to the PCM assembly and in such case the inside face of packaging may be selected for low rates of thermal energy transfer. In some cases there is no insulation (not shown) and then the inside face of PCM package assembly is selected for high convective heat transfer properties. In all cases, one or both faces of the PCM assembly may be comprised of special multi-layer facings which are specifically designed and selected based upon their unique heat transfer properties in addition to their ability to meet or exceed fire and smoke test standards, as required by design. [0088] There has thus been disclosed a system having a phase change material encapsulated between layers of heat transfer material to form mats which can be installed in the plenum areas of rooms within a building to generate energy consumption reduction and cost savings in the HVAC of the building.

4y

PRIOR ART [0001] The invention relates to a method for producing a shaft, and an apparatus containing such a shaft according to the general class of the independent claims. [0002] An apparatus was made known in the German utility-model patent GM 297 02 525.2 that is used, for example, to move window panes, sunroofs, or seats. In order to prevent an undesired axial end play of the armature shaft, it is proposed there that a damper rubber be pressed into a recess of the housing on at least one of its faces. The armature shaft presses a stop disk against this damping rubber. By means of the firmly locking into position and the elastic properties of the damping rubber, the armature shaft remains firmly fixed in place despite ageing processes and signs of wear. Additionally, the armature shaft can be installed very easily and cost-effectively together with the damping rubber. However, the elimination of the axial end play of the armature by means of such a damping rubber limits the maximally permissible tolerance in the production of the armature shaft. Narrower tolerances lead to higher production costs, however, which are undesired in a mass production of the armature shaft. ADVANTAGES OF THE INVENTION [0003] The method according to the invention having the features of claim 1 has the advantage that the favorable offset of end play with the damping rubber can continue to be used even when the shaft is fabricated not very exact to length in production. By introducing an additional working step, the manufacturing-related length of the shaft subject to tolerance can be decoupled from the elimination of the end play of the shaft. This also makes a very cost-effective and simple manufacture of the endless screw on the armature shaft possible. The end play is suppressed even more reliably as compared with earlier means for attaining the object of the invention, because the tolerance stack-ups are markedly lower after the material displacement than before. The useful life of the armature shaft is increased as a result and clicking noises produced when the direction of rotation changes are reliably prevented. [0004] Advantageous further developments of the method according to claim 1 are made possible by means of the features listed in the subclaims. If the material displacement takes place near an end of the shaft, the stability of the shaft across the entire length is largely maintained. Additionally, the material displacement at this point does not take up any additional space. If the material displacement is carried out by means of burnishing, this is a cost-effective, exact and easy-to-use process. Burnishing brings about a continuous elongation of the shaft that can be well-controlled. The burnishing results in an even constriction, which also has a very advantageous effect on the stability of the shaft. It is also possible to achieve the material displacement simply by means of squeezing, however. Such a working step is less expensive than burnishing, but it does not entirely achieve the same dimensional accuracy. [0005] If the length of the shaft is measured during the material displacement, the nominal dimension of the shaft can be achieved rapidly and exactly in one working cycle. [0006] It proves to be particularly favorable when the shaft is installed in the pole well of the electric motor before the material displacement is started. The tolerances that are stacking up are eliminated as a result. Moreover, the armature shaft then lies in “its” bearings, so that the dimensional accuracy and the position of the material displacement can be coordinated with the eventual site of application, particularly when burnishing the material displacement. [0007] It is advantageous to measure the length of the part of the installed shaft extending over the pole well, because the shaft can then be produced to the nominal dimension in the installed state. As a result, the tolerance stack-up of the end play can be markedly reduced. [0008] A further alternative is to measure the set value for the end play during material displacement with the shaft in the installed state. This has the advantage that the measured value of greatest interest—the end play—can be measured directly and it can be adjusted exactly to the set value by means of the material displacement. With this method, all manufacturing and fitting tolerances are completely eliminated. [0009] Efficient process engineering is a further advantage of material displacement by means of burnishing. The endless screw of the armature shaft can be produced and the material displacement can be carried out using just one tool. Even if one tool each is used for the burnishing of the endless screw and the burnishing of the material displacement, one complete working step is spared, because the shaft need be chucked only once for this process. This makes rapid and cost-effective production possible. [0010] The apparatus according to the invention having the features of the independent claim 9 has the advantage that a high-quality product with narrow tolerances is created despite initially great production tolerances of the shaft after installation. [0011] The material displacement located at the end of the shaft and the semicircular cross-sectional area of the circumferential groove have an advantageous effect on the preservation of stability of the shaft. It is advantageous that the shaft diameter can be reduced up to one-half of the original value. DIAGRAM [0012] An exemplary embodiment of an apparatus according to the invention is presented in the diagram, and it is explained in greater detail in the subsequent description. [0013] [0013]FIG. 1 shows a sectional drawing of an apparatus, and [0014] [0014]FIG. 2 shows an enlarged section of the shaft according to II in FIG. 1. DESCRIPTION [0015] An adjusting drive 10 is shown in FIG. 1 that comprises a motor 12 and a multisectional housing 16 enclosing a gear 14 . The motor 12 is electrically commutated and comprises an armature 18 , a commutator 20 , and an armature shaft 22 supported in bearings in multiple locations that extends into the region of the gear 14 . An endless screw 26 that communicates with a worm gear 24 is rolled onto the armature shaft 22 . This is supported at the faces 28 and 30 of the armature shaft 22 via stop disks 32 and 34 and at the housing 16 or a part of the housing 16 via a damping means 36 . [0016] The housing 16 comprises a recess 38 in the region of the face 28 of the armature shaft 22 , into which a damping rubber 40 is pressed as damping means 36 . The damping rubber 40 comprises a firmly specified elastic region 42 . The conception according to the invention therefore consists of the fact that the tolerances of the armature shaft 22 and the housing parts 16 , together with the assembly tolerances, may not exceed the dimension of the elastic region 42 (refer to FIG. 2), in order to effectively prevent play in the armature shaft. Instead of the damping rubber 40 , other damping means 36 such as spring elements or rigid stops are feasible as well. [0017] In order to adhere to such a narrow tolerance, according to the invention, the shaft 22 is brought to a nominal dimension 44 by means of material displacement 46 after the endless screw 26 is rolled on. The tolerance of this nominal dimension 44 is markedly smaller than the elastic region 42 of the damping rubber 40 . The material displacement 46 is realized by constricting the shaft 22 , by way of which the shaft 22 increases. The material displacement 46 is applied to one end region 29 between the endless screw 26 and the face 28 in a region where the shaft 22 is not radially supported in bearings. [0018] Methods of material displacement 46 are also feasible in which the shaft 22 is swaged, which would result in a shortening of the shaft 22 . Theoretically, there are a plurality of points on the shaft 22 where a material displacement would not disturb the structure. In order to maintain the overall stability of the shaft 22 , however, it presents itself to displace material on the ends 29 , 31 of the shaft 22 in the region toward their faces 28 , 30 . [0019] A simple method for material displacement 46 is given by the burnishing of the shaft 22 on its end 29 . This method is to be preferred over others because a burnishing device 54 must be held in front anyway in order to produce the endless screw 26 on the armature shaft 22 . The burnishing for material displacement 46 can thereby be carried out in one working step, i.e., simultaneously with the burnishing of the endless screw 26 26 , or one directly after the other during one chucking on the burnishing machine 54 . [0020] The length of the shaft 22 is measured simultaneously during the material displacement 46 . The shaft 22 is deformed until the length measurement of the armature shaft 22 shows the nominal dimension 44 . The nominal dimension 44 is thereby based on the entire length of the armature shaft 22 between its two faces 28 , 30 . [0021] In a second exemplary embodiment, the armature shaft 22 is installed in a part of the housing 16 —in a pole well housing 13 in this case—before its length is changed. The part of the armature shaft 22 extending over the pole well 13 is thereby measured simultaneously during its material displacement 46 . In this case, the nominal dimension 44 ′ (FIG. 1) is only based on the part of the armature shaft 22 extending out over the pole well 13 . The tolerances of the field frame 13 can thereby be eliminated as well. [0022] In a further exemplary embodiment, the length of the armature 22 is not measured as a nominal dimension 44 , but rather, the axial end play 44 ″ (indicated in FIG. 2 with a dotted line) of the shaft 22 is measured directly in its installed state. After the armature shaft 22 is completely installed and the housing 16 is fully assembled, the material displacement 46 of the armature shaft 22 is thereby carried out via one or more openings in the housing 16 . The armature axial end play 44 ″ is measured by means of an electric voltage or the current drawn by the electric motor that is applied to the electric motor 12 . If the end play is great, the motor 12 reaches its final speed already at relatively low amperage. If the length of the armature shaft 22 is now extended during the current measurement in this case, the armature shaft 22 presses axially against the damping rubber 40 at any time. As soon as the shaft 22 touches the damping rubber 40 , a certain braking torque is produced that can be measured via an increase in current or a decrease in speed of the motor 12 . If the current and/or the speed reach certain values, this is an indication that the end play has been eliminated or stopped in predetermined fashion. [0023] [0023]FIG. 2 shows the material displacement 46 on the end 29 of the armature shaft 22 in detail. The material displacement 46 is shaped in the form of a ring groove, i.e., encircling the entire shaft. Such a groove 48 is easy to produce by means of burnishing. The cross-sectional area 50 of the groove 48 is semicircular, i.e., the more the shaft 22 must be elongated, the deeper a segment of a circle is pressed into the shaft. It must be ensured that the cross-section 50 of the shaft 22 is not reduced to too great of an extent at the point of material displacement 46 . A reduction of the shaft diameter 52 to 50% of the original value is regarded as the limit value. [0024] In further exemplary embodiments, the cross-sectional area 50 of the ring-shaped groove 48 has a form other than a semicircular form. This is the case, for example, when the burnishing tool 54 is not shaped radially, but rather takes on another, random shape. Possible shapes of the cross-sectional area 50 are a trapezoid 50 ′ or a rectangle 50 ″ (dotted lines in FIG. 2). With such a profile, more material is displaced along one side of the trapezoid or rectangle from the beginning onward during burnishing, while little material is displaced at the beginning with a semicircular profile of the groove 48 . [0025] It is also feasible that the groove 48 is not ring-shaped around the entire circumference of the shaft 22 , but rather comprises one or more notches distributed around the circumference, for example. Such a method creates difficulties, however, with regard for a precise nominal dimension 44 of the shaft 44 , or it can produce unbalanced states. The selection of the exact point of material displacement 46 is variable between the face 28 and the start of the endless screw 26 on the motor shaft 22 .

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BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates to coated multi-denier mixed woven textile fabrics for use in inflatable vehicle occupant restraint systems and, more particularly, to coated textile fabrics woven with fibers and yarns of different materials and denier sizes in either or both of the warp and fill directions to provide air bags and side curtains with improved physical characteristics. 2. Description of the Related Art Current restraint systems for automotive vehicles include driver and passenger side air bags that are instantaneously gas-inflated by means such as by explosion of a pyrotechnic material at the time of a collision to provide a protective barrier between vehicle occupants and the vehicle structure. Much of the impact of a collision is absorbed by the air bag, thus preventing or lessening the possibility of serious bodily injury to occupants of the vehicle. Such air bags are located, typically, in a collapsed, folded condition housed in the steering wheel, to protect the driver, and in the dashboard, to protect a passenger seated next to the driver. Recently, the automotive industry also has introduced air bags that are stored in the back of the front seats or in the rear seats to protect the cabin occupants in the event of a collision occurring on either side of the vehicle. More recently still, a further safety feature that is made available for passenger vehicles, especially the so-called sport utility vehicles or SUVs, are side-impact protective inflatable side curtains designed to provide a cushioning effect in the event of side collisions or rollover accidents. These side curtains are stored in the roof of the vehicle and, in the event of a collision, deploy along the interior side walls of the SUV's cabin. Each of these different types of air bags has different design and physical property requirements, such as gas (air) holding permeability, air pressure and volume, puncture resistance and adhesion of the coating material to a woven substrate. For example, driver side air bags must have little or no permeability and, as a result, are often made from a material having very little or no permeability. Passenger side air bags, on the other hand, require a controlled permeability, and are most often made from materials having some degree of permeability. Furthermore, all such vehicle air restraint devices must have superior packageability and anti-blocking qualities. Packageability refers to the ability for a relatively large device to be packaged in a relatively small space. Anti-blocking refers to the ability of the device to deploy almost instantaneously without any resistance caused by the material sticking to itself. The air holding capability of side curtains is critical since they must remain inflated for an extended period of time to protect passengers in multiple rollovers. Unlike air bags which are designed to inflate instantaneously, and to deflate almost immediately after inflation in order to avoid injury to the driver and front seat passenger, air curtains used in SUVs, or in ordinary passenger vehicles, must be capable of remaining inflated in the range of from about three (3) to about twelve (12) seconds, depending upon the size of the curtain and the type of vehicle. An average passenger vehicle would require a side curtain of from about 60 inches to about 120 inches in length as measured along the length of the vehicle, and a larger vehicle, such as a minivan, would require an even longer side curtain. The maximum inflation period of a side curtain should be sufficient to protect the cabin occupants during three (3) rollovers, the maximum usually experienced in such incidents. When such air bags are deployed, depending upon their specific location or application, they may be subjected to pressures within a relatively broad range. For example, air bag deployment pressures are generally in the range of from about 50 kilopascals (kpa) to about 450 kpa, which corresponds generally to a range of from about 7.4 (pounds per square inch) psi to about 66.2 psi. Accordingly, there is a need for fabric products and air bags which can be made to be relatively impermeable to fluids under such anticipated pressures while being relatively light in weight. One means of improving air holding capability in vehicle restraint systems has been through coatings such as chloroprene and silicone rubber coatings, applied to the textile substrate. Wherever coated fabrics are used there exists the problem of insufficiency of adhesion of the coating to the fabric substrate. More particularly, the smoother the substrate surface, generally the more difficult it is to obtain strong adhesion of the coating material to the substrate. Furthermore, with some coatings such as silicone rubber, radio frequency (RF) heat sealing techniques cannot be used to form the bag. Thus in such instances bags are usually made by stitching, a process which requires the addition of an adhesive sealant in the stitched areas. There have recently been developed improved polyurethane, acrylic, polyamide and silicone coatings that are coated in layers on the fabric substrates. It has been found that adhesion characteristics are greatly improved with such layered coatings. Examples of such coated fabrics and methods of coating such fabrics are disclosed in commonly assigned application Ser. Nos. 09/327,243, 09/327,244 and 09/327,245, filed Jun. 7, 1999, the disclosures of which are incorporated herein by reference and made a part of this disclosure. In general, yarn sizes are measured by a well known weight indicator referred to as “denier” and identified as units “D”. The greater the denier (D), the thicker and heavier is one unit of length of the yarn. The most common denier yarns presently used in such air holding devices are 420D nylon, in a 46×46 or 49×49 count weave, for driver side air bags, and 630D nylon, in a 41×41 count weave, for passenger side air bags. However, deniers as low as 210D, in a 72×72 count weave, have been used where the air bag must be housed in a tight fit, and, to a lesser extent, a 315D yarn, in a 60×60 count weave. U.S. Pat. No. 5,704,402 discloses an uncoated air bag fabric in which weave constructions are stated to provide air bags with air permeability which does not increase by more than about fifty percent from the untensioned state when the fabric is subjected to tensile forces. These textile fabrics are stated to include yarns of different deniers within the weaves. Air bags of this type are typically used as passenger side air bags and are unsuitable for use in driver side air bags or side curtains, which must have little or no air permeability. U.S. Pat. No. 5,863,644 discloses woven or laid structures using hybrid yarns comprising reinforcing filaments and lower melting matrix filaments composed of thermoplastic polymers to form textile sheet materials of adjustable gas and/or liquid permeability. During the formation of textile fabrics in accordance with the disclosure, polyester fibers in the weaves are melted by the application of heat to form textile sheet materials which are stated to have predetermined gas and/or liquid permeability. U.S. Pat. No. 5,881,776 relates to a rapier woven low permeability air bag fabric and an air bag for use in a motor vehicle. The fabric is of plain weave construction and has an air permeability of less than approximately 5.0 CFM. The air bag is comprised of a plurality of panels connected together about their respective peripheries. While these known fabrics represent somewhat successful attempts to control permeability through the incorporation of one or more features, none of these attempts have adequately solved the problem of providing a fabric of adequate impermeability whereby controlled permeability may be incorporated, where required. The present invention relates to a mixed woven coated textile fabric having yarns of different denier sizes woven for use in such inflatable air bag or side curtain restraint systems which not only provides improved adhesion of the coating to the textile substrate, but more effectively limits permeability and provides enhanced physical properties of the woven substrate, yet leaving available controlled permeability through the use of selectively sized venting apertures or other means. SUMMARY OF THE INVENTION It has been found that by weaving yarns of different deniers, as for example, a low denier yarn with a higher denier yarn of the same or different continuous filamentary or fibrous materials in either or both of the warp or fill directions, coating adhesion and other physical properties of the woven textile fabric are greatly improved. In particular, if for example, nylon yarns of different deniers are interwoven, the difference in deniers creates an uneven, or relatively rough surface to which polymer coatings will adhere more securely than if the surface were smooth. Further, if nylon yarns of one denier are interwoven with, for example, yarns of a different denier and different fiber material, such as aramid fiber, the woven textile fabric would not only have greater adhesion capability for coatings, but would also have increased puncture resistance properties. In addition, the use of low denier yarns woven with high denier yarns greatly improves the packageability of the air bag or side curtain for storage, while reducing the weight of the bag. Broadly stated, fabrics for such air bags generally can weigh from about 4.0 ounces per square yard (osy) to about 10.0 ounces per square yard (osy). In actual use, however, on the average, fabrics for such air bags generally weigh from about 5 to about 6 ounces per square yard. It has now been found that by combining different size and types of yarns in a single fabric weave, the strength and weight of the resultant fabric can be selectively controlled. For example, yarns of a given denier can be utilized in the warp with yarns of a lesser denier in the fill direction. Also, the warp yarns can be comprised of yarns of different deniers in an alternating regular or random fashion and the fill yarns can be comprised of yarns of the same denier or of varying or alternating deniers. Moreover, individual yarns can be comprised of continuous filaments of varying sizes blended together, or blended with other natural or synthetic fibers to control strength and weight factors inherent in the final fabric product. As will be seen hereinbelow, such combinations provide not only strength and weight benefits, but also surface adhesion properties for coating the fabrics to render them substantially impermeable to fluid pressure. A coated woven textile fabric is disclosed, which comprises synthetic yarns of more than one denier, and a polymeric coating on at least one side thereof, the yarns and the polymeric coating being preselected respectively in deniers and thickness so as to render the fabric substantially impermeable to fluid under pressure. According to one preferred embodiment the fabric is comprised of warp yarns of about 315D nylon and fill yarns of about 210D nylon. According to another embodiment the fabric is comprised of warp yarns of about 420D nylon and fill yarns of about 315D nylon. According to yet another embodiment the fabric is comprised of warp yarns of from about 315D to about 420D nylon and fill yarns of from about 195D to about 380D aramid. An embodiment of the invention is disclosed wherein the fabric is comprised of warp yarns of more than one denier and fill yarns of more than one denier. This fabric may be comprised of warp yarns of from about 210D to about 315D nylon and fill yarns of about 210D nylon, and the yarns are selected from the group consisting of nylon, polyester, aramid and graphite and combinations thereof. The coating on at least one side of the fabric is preferably a thin polyurethane layer, but may also be comprised of polysiloxane, polyamide or acrylic type polymers. The same or an alternative coating may be provided on the other side of the fabric. It has been found that the coated fabric according to the invention provides excellent fluid impermeability while retaining packageability and anti-blocking qualities. A flexible lightweight air bag for receiving and containing fluid under pressure for use in a vehicle air restraint system is also disclosed, which comprises a textile fabric according to the invention which is woven of synthetic yarns of more than one denier, and has a polymeric coating on at least one side of the fabric. The yarns and the polymeric coating are preselected respectively in deniers and thickness so as to render the air bag capable of receiving and retaining fluid under pressure in a vehicle air restraint system. The polymeric coated fabric is substantially impermeable to the fluid. The coating on at least one side of the fabric is preferably a thin polyurethane layer, but may also be comprised of polysiloxane, polyamide or acrylic type polymers. The same or an alternative coating may be provided on the other side of the fabric forming the air bag. It has been found that the fabric according to the invention provides excellent fluid impermeability while retaining packageability and anti-blocking qualities. BRIEF DESCRIPTION OF THE DRAWINGS Preferred embodiments of the invention are described hereinbelow with reference to the drawings, wherein: FIG. 1 is a partial cross-sectional side elevational view of a driver's side of an automobile showing a deployed air holding restraint bag made of the lightweight textile fabric constructed according to the present invention; FIG. 2 is a greatly enlarged, partial schematic representation of a lightweight woven fabric of the invention, comprised of nylon yarns of different deniers; FIG. 3 is a cross-sectional view of the fabric of FIG. 2, taken along line 3 — 3 of FIG. 2, with a polymeric coating added to one side thereof; FIG. 4 is a greatly enlarged partial schematic view of an alternative embodiment of the lightweight woven fabric of the invention, comprised of nylon yarns of alternative different deniers; FIG. 5 is a cross-sectional view of the fabric of FIG. 4, taken along line 5 — 5 of FIG. 4 with a polymeric coating added to one side thereof; FIG. 6 is a greatly enlarged partial schematic view of another alternative embodiment of the lightweight fabric of the invention, comprised of nylon and aramid yarns of different deniers; FIG. 7 is a cross-sectional view of the fabric of FIG. 6, taken along line 7 — 7 of FIG. 6, illustrating an alternative embodiment of the invention wherein a polyurethane coating is added to both sides of the fabric; FIG. 8 is a greatly enlarged view of still another alternative embodiment of the lightweight fabric of the invention, comprised of blended yarns of synthetic filamentary materials and natural fibrous materials such as nylon and cotton yarns of different deniers; and FIG. 9 is a cross-sectional view of the fabric of FIG. 8, taken along line 9 — 9 of FIG. 8, with a polymeric coating added to one side thereof. DETAILED DESCRIPTION OF THE INVENTION According to the present invention it has been found that coated multi-denier mixed woven textile fabrics for use in inflatable air bags or side curtains, whether of the same or different materials, provide greatly improved coating adhesion and other desired physical properties over a textile fabric woven from yarns of the same denier. In particular, it has been found that a combination of woven yarns of differing deniers form a fabric having ridges and valleys in the weave which provide a much greater surface area for adhesion of synthetic polymeric coatings to the woven substrate which, in turn, increases the adhesion of the coating material to the woven fabric substrate. Further, the textile material of the present invention can be woven to specific tensile strength or puncture resistance requirements by selectively increasing or decreasing the denier sizes of the yarns or by introducing puncture resistant or other types of materials into the weave. Although the preferred textile materials for use in air bags are yarns of nylon and polyester, other synthetic materials can be used according to the invention. For example, aramid yarns such as Kevlar®, produced by E. I. DuPont de Nemours & Company, Spectra® produced by Allied Signal Corporation, or PBI®, produced by Celanese Corporation, can be used in the weave. Non-polymeric materials such as graphite, natural fibers or blends of natural fibers such as cotton, and synthetic filaments such as polyester can also be used to advantage in the weave. It has been found that woven combination fabrics that incorporate aramid yarns provide greater puncture protection to the side curtain where danger from broken glass exists. Weave combinations, such as nylon and cotton, for example, can also be used to create different physical properties, such as providing additional flexibility to the coated fabric. Weaves of aramid yarns alone may also be used in the invention. In general, the synthetic yarns are each formed of bundles of continuous filaments temporarily held together for weaving by a suitable sizing compound such as polyvinyl alcohol, which also provides lubricity for weaving. After weaving, the sizing compound is generally removed from the fabric by a known scouring process. Polymeric coated fabrics for uses in air-holding vehicle restraint systems and methods of coating such fabrics are disclosed in the aforementioned commonly assigned application Ser. Nos. 09/327,243, 09/327,244 and 09/327,245, filed Jun. 7, 1999, which are incorporated herein by reference. When the woven textiles of the present invention are coated as, for example, with polyurethane, silicone rubber, polysiloxane, or polyamide and acrylic type polymers, the air holding characteristics of the woven textile can be adjusted as required such as by vents or other appropriate means for the particular application involved. This allows for the use of different denier materials to be used for the driver side and front passenger type air bags than those that are used for the side curtains. Also, the thickness of the polymeric coating can be pre-selected to be combined most effectively with yarns of differing and preselected deniers to provide a coated fabric which is most effective in terms of pressure fluid impermeability, packageability, puncture resistance and the like. The yarns of the present invention can be of deniers ranging from about 70D to about 1200D to produce products having weave counts of from about 20 to about 150 yarns per inch. Textile weights can range from about 4.0 to about 10.0 ounces per square yard (osy). These types of multi-denier weave combinations exhibit improved tear resistance and adhesion on lightweight denier textiles to be used in air bag and side curtain applications. Higher denier nylon and aramid yarns provide greater tear resistance. In addition, these types of denier combinations and constructions can be woven with unsized yarns utilizing LDPF (low denier per filament) Hi-tenacity yarns, manufactured by DuPont, or with high shrinkage yarns. The woven textiles of the invention can also be blends of aramid yarn with nylon, polyester or other synthetic yarns. For purposes of this invention, weaves of different types are contemplated, such as, for example: plain weaves, consisting of yarns in an alternating fashion, one over and one under every other yarn; basket weaves, in which two or more warp yarns are alternately interlaced over and under each other; leno yarns, in which the yarns are locked in place by crossing two or more warp threads over each other and interlacing with one or more filling threads; twill weaves, characterized by a diagonal rib created by one warp yarn floating over at least two filling yarns; four harness satin weave where a filling yarn floats over three warp yarns and under one; an eight harness satin weave, which is similar to the four harness satin weave except that one filling yarn floats over seven warp yarns and under one; and high modulus weave where high impact resistance and high strength are required. Detailed descriptions of such weaves are described in textile publications such as a publication of Clark-Schwebel Joint Ventures, CS-Interglas A.G., the disclosure of which is incorporated herein by reference. A preferred construction for the multi-denier weave of the invention is a plain weave of 315D×420D nylon, with a weave count of 46×46 . A weave of this construction has been found to provide greatly improved adhesion characteristics, better packageability and excellent tensile strength. As disclosed herein, other deniers can be used within the ranges specified to provide the advantages of the invention. Similarly, when a combination of different yarns is used in the weave, such as nylon and aramid yarns, the preferred weave would be a warp nylon of 315D or 420D with a 195D or 380D Kevlar® yarn. In general, it has been found that by combining low denier yarns with high denier yarns, the lower denier yarns reduce the weight of the fabric, yet the fabric retains the benefits of strength and weight through the high denier yarns incorporated therein. Referring now to FIG. 1, there is shown a partial cross-sectional side elevational view of a driver's side of an automobile 10 showing a deployed air restraint bag 12 made of a lightweight coated fabric constructed according to the present invention. The air bag is preferably constructed of a plain weave fabric as will be described hereinbelow, coated on one side with a thin layer of polyurethane. The coating is preferably 0.001 to 0.010 inch in thickness (i.e., 1-10 mils), but may be up to about 0.020 inch in thickness (i.e., 20 mils) without substantially compromising packageability. The air restraint bag shown is exemplary of a driver's side air bag which is deployed from the steering column of the vehicle. Although not shown, as noted previously, air restraint systems including side curtains are also contemplated within the scope of the invention. One preferred embodiment of the invention, is shown in FIG. 2, in which a lightweight woven fabric 14 is comprised of nylon yarns 16 of 315D in the warp direction and nylon yarns 18 of 210D in the fill direction. This blend, when coated with a polymeric coating 20 such as polyurethane, as shown in FIG. 3, provides a woven textile air bag fabric of the type shown in FIG. 1, with little or no permeablility, improved packageability and strength, as well as improved coating adhesion properties. In particular, warp yarns 16 and fill yarns 18 are comprised of bundled nylon continuous filaments having little or no twist and held together by a suitable sizing agent such as polyvinyl alcohol, a compound which provides lubricity for weaving. The resulting fabric is as shown with yarns which are actually woven together in close proximity to permit little or no air permeability between the yarns. The greatly enlarged representation in the drawings are presented for illustration purposes whereby the spaces between the yarns are also greatly enlarged. In particular, it has been found that the particular construction of yarn deniers disclosed herein, combined with the stated preferred coating thickness, provides substantial impermeability to fluid under pressure, while retaining high strength, low weight, superior packageability and non-blocking qualities. Moreover, the fabric's puncture resistance can be modified by combining aramid fibers such as Kevlar® into the weave. In FIG. 3, a significant feature of the weave of FIG. 2 is illustrated by enlarged cross-sectional view, in that the different size yarns create a relatively uneven surface, with small crevices and interstices which more readily promote adhesion of the polyurethane coating 20 to the fabric 14 as shown. Other coating materials such as chloroprene and silicone rubber or the like have been found to adhere to the subject fabric with comparable improvement. In FIG. 4 there is shown a weave 22 of nylon yarns 24 of 420D in the warp direction and nylon yarns 26 of 315D in the fill direction. This combination of yarn weights would more commonly be used in driver side air bags or side curtains. Moreover, the weave shown in FIG. 4 provides much greater adhesion for coatings than a weave comprised entirely of a yarn of only one denier, as is evident from the enlarged cross-sectional view of the fabric shown in FIG. 5, with coating 28 of polyurethane added thereto on one side. Alternatively, the same type of coating may be placed on the opposite side of the fabric. In FIG. 6 there is shown a greatly enlarged view of a woven fabric 30 of nylon and aramid yarns in which the warp yarns 32 are comprised of 310D nylon and fill yarns 34 are aramid yarns such as 195D Kevlar® brand aramid yarns. This weave provides improved adhesion of the polymeric coating by providing peaks and valleys between the yarns, as well as small crevices and interstices therebetween, all facilitated by the combination of different yarn sizes. Also greatly improved puncture resistant properties are provided by the nylon and the aramid yarns which renders the material especially suitable for side curtains. It should be understood that weaves in which the aramid yarns are woven in the warp direction are contemplated in this invention as well. Referring to FIG. 7 there is shown a cross-sectional view of the woven fabric shown in FIG. 6, showing the multi-filament nylon yarns 32 in cross-section which are greater in size—preferably twice the size—than the Kevlar® fill yarns 34 . In FIG. 7, there is also illustrated still another alternative embodiment of the present invention whereby polymeric coatings 36 , 37 are respectively added to each side of the fabric as shown. It has been found that the improved adhesion between the fabric 30 and the coatings 36 , 37 , combined with the combination of yarn sizes as disclosed herein, provides a fabric having little or no fluid permeability without compromising packageability. Accordingly, the fabric shown uncoated in FIG. 6 will provide a finished air bag having superior qualities when coated on both sides in FIG. 7 . Referring now to FIG. 8, there is shown a top plan view greatly enlarged, of a weave construction 40 of a combination of yarns comprised of warp yarns 40 of 315D nylon continuous filaments blended with cotton fibers with standard twist to retain the fibers and the continuous filaments together in yarn form. In the woven fabric of FIG. 8, the blended yarns 40 in the warp direction are about 315D and the blended yarns 44 in the fill direction are about 160D, or about one half the denier of the blended warp yarns 40 . FIG. 9 is a cross-sectional view taken along line 9 — 9 of FIG. 8, with polyurethane coating 44 added on one side to promote impermeability. It should be understood that yarns of other synthetic and natural fibers can be used in the invention. In particular, yarns of polyester fibers are contemplated, with weaves of different denier sizes as with nylon. One example of a polyester fabric of the invention would be a weave of 440D polyester with a 650D polyester. Blended yarns of polyester and cotton are also contemplated for use in the invention. Other blends and weaves can also be used in the invention. For example, yarns of different size deniers can be used in either or both of the warp and fill directions. Thus, a weave could comprise both 210D and 315D nylon yarns in either or both of the warp and fill directions. Other denier and fiber combinations are contemplated herein and can be used in the invention. As can be seen, the present invention provides a coated woven multi-denier textile fabric for use in an air bag or side curtain having substantially improved adhesion and physical properties. Such fabrics may be of the same or different yarns and of two or more deniers. Moreover, as noted, various combinations of yarn deniers and sizes can be utilized in the fabric to control strength and weight factors. For example, as noted, different combinations of yarn deniers can be utilized in both the warp and the fill directions, depending upon the intended application. Moreover, the actual yarns can be comprised of continuous synthetic filaments of different sizes, or filaments and natural or synthetic fibers of different sizes blended to form the yarn. While the preferred embodiments of the invention have been illustrated and described, using specific terms, such description has been for illustrative purposes only, and it should be understood that changes and variations may be made without departing from the spirit and scope of the invention which is defined by the claims appended hereto.

4y

TECHNICAL FIELD OF THE INVENTION [0001] The present invention relates to novel improvements to an apparatus for uniformly decomposing compressed tablets into a uniform size powder form. More particularly, the present invention is directed to improvements to the rotor cap of such apparatus where such improvements allow the rotor cap to be easily removed from the apparatus to convert the apparatus from right hand operation to left hand operation and vice versa. Such improves also allow for disassembly and cleaning. BACKGROUND OF THE INVENTION [0002] The present invention relates to novel improvements of an apparatus for uniformly decomposing compressed tablets into a uniform size powder form. [0003] The apparatus is configured to controllably crush and shave tablets in a compressed form using a minimum amount of manual force so as to deposit the decomposed tablet powder directly into a universal patient cup of the type standardized for use in hospitals. The improved rotor cap allows the apparatus to be quickly converted from left hand to right hand operation (and vice versa). In addition, such improves allow the apparatus to be disassembled more easily for cleaning and maintenance. [0004] The present invention relates to an apparatus for solving a number of universally recognized problems. It has long been recognized that one of the preferred ways of administering medication is orally in tablet form. Medication in tablet form is the least expensive form in which to manufacture and package medication and is a preferred non-invasive delivery method. Further, compressed tablet form medication is the best form to avoid tampering. [0005] There are several recognized problems associated with administering medication in tablet form. A principal known problem is that a large number of people are subject to gag reflex response which will not permit them to swallow a tablet in solid form. A large number of bedridden patients or patients disposed in a reclined position are also not capable of swallowing tablets in solid form or in granular form. Persons or patients having to use nasalgastrological feeding tubes or other types of feeding tubes require that their medication be presented in a solution or liquid form. Medication has heretofore been taken in liquid form through a straw or in a powdered form when mixed with food. The above problems that exist with human patients also exist in the field of veterinary medicine. [0006] Heretofore, the preferred solution to the abovementioned problems of administering oral medication in tablet form is to grind, abrade (comminute) and compress fracture (crush). Heretofore, devices and apparatus for decomposing tablets in fractured particle form or in granular or in powder form have been classified in U.S. Class 241, Subclasses 168, 169 and 273 with comminution or defracture devices. [0007] Typical of such crushing devices is shown in U.S. Pat. No. 2,892,595 which shows a pair of plastic nesting conical mortar and pestle assemblies. The problem with such crushing devices is similar to the well known pharmacists hard stone-like mortar and pestle which cannot generate the necessary forces to fracture and decompose ultra-hard tablets such as calcium gluconate, etc. Such crushing devices leave particles on both assemblies that are not easily dislodged when it is necessary to transfer the crushed tablet in a glass or receptacle for consumption. [0008] Typical of such grating devices is shown in U.S. Pat. No. 2,804,896 which shows a household food grater or slicer having a hollow spool or cylinder provided with rows of sharp edge grating apertures formed therein. The article of food to be grated is placed in a hopper and a shaped follower is manually pressed down on the top of the food. This type grating device leaves a substantial amount of ungrated food in the hopper, apertures and the hollow spool, thus, cannot be used for comminuting medication in its present form or in a modified form without wasting a portion of the prescribed medication. [0009] U.S. Pat. No. 4,209,136 shows a device for chopping and crushing medicinal tablets which device is adapted from a food chopper. This chopping device will reduce tablets to a granular form by a crushing or chopping action but leaves medication on the crusher foot and in the container when transfer is made to a glass or receptacle when used for consumption. [0010] Referring now to the commonly owned U.S. Pat. No. 5,148,995 issued to Richard F. Hurst, such apparatus is configured for uniformly decomposing compressed tablets into a uniform size powder form. The U.S. Pat. No. 5,148,995 is hereby incorporated by this reference for all that it discloses. While such apparatus works well for its intended purposes, one drawback of the U.S. Pat. No. 5,148,995 device is that it can not be easily converted to from left hand operation to right hand operation (or vice versa) nor can be easily disassembled for cleaning. [0011] What is needed is an improved apparatus configured for easy conversion from a first operation orientation to a second operation orientation as well as facilitating disassembly. SUMMARY OF THE INVENTIONS [0012] Some of the objects and advantages of the invention will now be set forth in the following description, while other objects and advantages of the invention may be obvious from the description, or may be learned through practice of the invention. [0013] Broadly speaking, one principle object of the present invention is to provide an apparatus for decomposing compressed tablets into predetermined powder size and depositing the powder directly into a universal patient cup for direct use by a patient where the apparatus comprises enhanced features to allow operation orientation conversion. [0014] It is another primary object of the present invention to provide a novel apparatus for decomposing compressed tablets into a powder form comprising an improved rotor cap configured to allow conversion of the apparatus from one operation orientation to a second operation orientation. [0015] It is another primary object of the present invention to provide a novel apparatus for decomposing compressed tablets into a powder form comprising an improved rotor cap configured to allow conversion of the apparatus from a first operation orientation to a second operation orientation while also allowing for disassembly. [0016] Additional embodiments of the present subject matter, not necessarily expressed in this summarized section, may include and incorporate various combinations of aspects of features or parts referenced in the summarized objectives above, and/or features or components as otherwise discussed in this application. [0017] Those of ordinary skill in the art will better appreciate the features and aspects of such embodiments, and others, upon review of the remainder of the specification. BRIEF DESCRIPTION OF THE DRAWINGS [0018] A full and enabling description of the present subject matter, including the best mode thereof, directed to one of ordinary skill in the art, is set forth in the specification, which makes reference to the appended figures, in which: [0019] FIG. 1 is a side view in elevation of a preferred embodiment tablet decomposing apparatus according to the present invention; [0020] FIG. 2 is a front view of the apparatus shown in FIG. 1 ; [0021] FIG. 3 is a partial top view showing the rotor and crank mounted in the housing of FIGS. 1 and 2 and showing a pre-fracturing recessed trough in the handle of the housing; [0022] FIG. 4 is an enlarged view of a rotor showing dual anticlog slicing ribs according to the preferred embodiment of the present invention; [0023] FIG. 5 is an enlarge view showing another rotor having dual cutting ribs which have a tendency to clog; [0024] FIG. 6 is an enlarged view of a rotor having a continuous spiral cutting rib and a cleaning brush of the type which mounts in the housing juxtaposed the slicing ribs; [0025] FIG. 7 is a front view and partial section of the motorized version of the apparatus shown in FIGS. 1 through 6 ; [0026] FIG. 8 is an enlarge schematic view of a continuous spiral slicing rib prior to slicing and cutting a tablet which is captured between the presser foot and one of the rotors of the apparatus from a crushing action; and [0027] FIG. 9 is a side elevated view of one possible alternative embodiment of an end cap ( 50 ). [0028] Repeat use of reference characters throughout the present specification and appended drawings is intended to represent the same or analogous features or elements of the present technology. DESCRIPTION OF THE PREFERRED EMBODIMENTS [0029] Reference now will be made in detail to the embodiments of the invention, one or more examples of which are set forth below. Each example is provided by way of explanation of the invention, not limitation of the invention. In fact, it will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the scope or spirit of the invention. For instance, features illustrated or described as part of one embodiment can be used on another embodiment to yield a still further embodiment. Thus, it is intended that the present invention covers such modifications and variations as come within the scope of the appended claims and their equivalents. Other objects, features, and aspects of the present invention are disclosed in or may be determined from the following detailed description. Repeat use of reference characters is intended to represent same or analogous features, elements or steps. It is to be understood by one of ordinary skill in the art that the present discussion is a description of exemplary embodiments only, and is not intended as limiting the broader aspects of the present invention. [0030] For the purposes of this document two or more items are “mechanically associated” by bringing them together or into relationship with each other in any number of ways including a direct or indirect physical connection that may be releasable (snaps, rivets, screws, bolts, etc.) and/or movable (rotating, pivoting, oscillating, etc.) Similarly, two or more items are “electrically associated” by bringing them together or into relationship with each other in any number of ways including: (a) a direct, indirect or inductive communication connection, and (b) a direct/indirect or inductive power connection. Additionally, while the drawings may illustrate various electronic components of a system connected by a single line, it will be appreciated that such lines may represent one or more signal paths, power connections, electrical connections and/or cables as required by the embodiment of interest. [0031] Refer now to FIG. 1 showing a side view in elevation of a preferred embodiment tablet decomposing apparatus ( 10 ) which comprises a housing assembly ( 11 ), a pressor foot assembly ( 12 ), and a rotor associated with a crank assembly ( 13 ) further associated with housing ( 11 ). The housing ( 11 ) is provided with a tapered feed hopper ( 14 , 14 A) in which tablets may be placed directly or pre-crushed (pre-fractured) by placing the tablet in the pre-fracturing recess ( 15 ) and crushing and fracturing the tablets placed in the pre-fracturing recess ( 15 ) by engaging them with the pre-fracturing blade ( 16 ) mounted on the pressor foot assembly ( 12 ). Blade ( 16 ) may be made from a piece of sharp metal or integrally molded as a blade as part of the assembly ( 12 ). The pressor foot ( 17 ) is provided with a partial cylindrical shape which is adapted to match and fit the tops of the slicing ribs (not shown) which rotate in the cylindrical plane ( 18 ). As will be explained in more detail hereinafter, tablets caught between the pressor foot ( 17 ) and the plane of revolution ( 18 ) of the slicing ribs will be sliced and pulverized while being held by the forward portion of the feed hopper ( 14 ). Discharge chute ( 19 ) is shown having the same width as the diameter of the cylindrical plane ( 18 ) of the slicing ribs and is larger than the opening of the tapered feed hopper ( 14 ) at its engagement point with the slicing rotor. A patient's cup ( 21 ) is shown held in place against the bottom surface ( 22 ) of the housing ( 11 ). The patient's cup ( 21 ) is a standard plastic cup having different types of calibrations or graduations thereon. Normally the cup is provided with graduations up to one fluid ounce, graduations up to eight drams, graduations up to two tablespoons, graduations up to 30 cubic centimeters and graduations up to 30 milliliters. Such cups are known as universal patients' cups and are used throughout the world. Since the cup ( 21 ) is standard and of uniform size throughout the world, it readily fits into an annular tapered ring provided as an extension on the housing assembly ( 11 ). It should be appreciated, however, that apparatus ( 10 ) may be used with non standard cups without departing from the scope and spirit of the present invention. [0032] In the process of decomposing tablets, the size of the powder can be controlled by controlling the height of the slicing ribs as will be explained hereinafter. Since a very fine powder traps below the top of the slicing rib, a cleaning brush (not shown) may be inserted in the brush recess ( 24 ) and forms an effective means for dislodging powder. A thumb rest ( 25 ) is provided on pressor foot assembly ( 12 ) and is positioned there along to permit a person holding the decomposing apparatus ( 10 ) in one hand to apply sufficient pressure on the pre-fracturing blade ( 16 ) and pressor foot ( 17 ) to completely decompose tablets in the decomposing apparatus. [0033] Refer now to FIG. 2 showing a front view of the apparatus ( 10 ) shown in FIG. 1 . The patient's cup ( 21 ) is shown mounted in the annular tapered ring ( 23 ) which has an opening ( 26 ) which permits the top of the patient's cup ( 21 ) to be squeezed at the top and slid into place tightly against bottom surface ( 22 ). The flexing of cup ( 21 ) tightly holds the cup ( 21 ) against the surface ( 22 ) when released. [0034] The rotor assembly ( 13 ) is shown comprising a crank having a rotatable knob ( 27 ) which snaps through recess ( 28 ) during assembly. Housing ( 11 ) is provided with cylindrical bearing recesses ( 33 ) which are adapted to receive the bearings associated with the rotor in a manner which provides a seal and yet provides rotatable movement as will be explained hereinafter. [0035] Similarly end cap ( 29 ) snaps into recess ( 32 ) as shown in FIG. 2 . End cap ( 29 ) may comprise an anti-friction flange ( 31 ) and is preferably configured to urge the opposite anti-friction flange ( 31 A) into engagement with the side of the housing ( 11 ). [0036] Referring now to FIG. 9 , one alternative exemplary embodiment of the end cap (end cap ( 50 )) is presented. End cap ( 50 ) comprises a discontinuous annular ring ( 52 ) associated with at least one depending section ( 54 ). For the presently preferred embodiment, there are two depending sections ( 54 ). Depending section ( 54 ) extends from side ( 60 ) of discontinuous annular ring ( 52 ) to a point distal from discontinuous annular ring ( 52 ) thereby defining distal end ( 53 ). For such embodiment, depending section ( 54 ) comprises a partially cylindrical surface defined by two opposing faces, outer face ( 65 ) and inter face ( 64 ). While the two depending sections are shown opposing each other it will be appreciated that other configurations may be used. Depending section ( 54 ) further comprises latching surface ( 56 ) configure to mechanically associate with rotor assembly ( 13 ). As depicted in FIG. 9 , latching surface ( 56 ) defines a raised surface which is configured to reasably associate with rotor assembly ( 13 ). [0037] End cap ( 50 ) further comprises two opposed pinching surfaces ( 58 ) configured to compress the discontinuous ring by at least partially closing gap ( 56 ) when a pinching force is applied to the opposed pinching surfaces ( 58 ). For the presently preferred embodiment, such pinching surfaces are finger grips. It will be appreciated that when a pinching force is applied to pinching surfaces ( 58 ), discontinuous ring ( 52 ) is compressed or deformed along gap ( 56 ) thereby disassociating latching surface ( 56 ) from rotor assembly ( 13 ). Such an end cap ( 50 ) configuration allows the end cap ( 50 ) to be disassociated from rotor assembly ( 13 ) thereby allowing rotor assembly ( 13 ) to be removed from apparatus ( 10 ) without the use of an end cap removal tool. [0038] To identify a particular apparatus ( 10 ) device or apparatus ( 10 ) use, at least one pinching surface ( 58 ) may be configured to receive a coding tab ( 66 ). Coding tab ( 66 ) is simply a tab that may be used to distinguish one apparatus ( 10 ) from another. For example, coding tab ( 66 ) may be of a particular color or display a particular number. Such coding tabs are useful in performing several functions including: (a) distinguishing a first apparatus ( 10 ) owned by person A from a second apparatus ( 10 ) owned by person B, (b) distinguishing apparatus ( 10 ) blade configurations, (c) distinguishing an apparatus ( 10 ) that should only be use to process a particular type of pill or substance. As shown in FIG. 9 , for the presently preferred embodiment, coding tab ( 66 ) is an insert that fits over pinching surfaces ( 58 ). [0039] Refer back to FIG. 3 showing a top view of the housing assembly ( 11 ) with rotor assembly ( 13 ) mounted therein and the pressor foot assembly ( 12 ) removed. The pre-fracturing recess ( 15 ) is shown tapered and becoming progressively deeper as it approaches the tapered feed hopper ( 14 ) having a tapered side wall ( 14 A). A hinge extension ( 34 ) is provided on the handle of the housing assembly ( 11 ) and adapted to receive a pin in the recess ( 35 ) to pivotally mount the pressor foot assembly ( 12 ) thereon. When using modern injection molded techniques, it is possible to eliminate the hinge extension ( 34 ) and substitute a flexible and narrow molded sheet of plastic for the hinge ( 34 ) and pin ( 35 ). [0040] For one embodiment of the invention, the shaving means ( 36 ) preferably fills the hopper ( 14 ) and comprises raised ribs or other slicing/pulverizing means on an imperforate cylinder which preferably completely fills the hopper from wall to wall. [0041] Refer now to FIG. 4 showing an enlarged view of the shaving means ( 36 ) on a rotor assembly ( 13 ). Cylindrical bearings ( 33 A) and ( 33 B) fit snugly but rotatably in the bearing recesses ( 33 ) shown in FIGS. 2 and 3 . Shaving means ( 36 ) comprise a pair of raised ribs ( 37 ) that are discontinuous. The forward edges of ribs ( 37 ) are indicated at the lead line of the numerals ( 37 ) and are sharp protruding edges which cut or shave the bottom of a tablet which is placed in the tapered feed hopper ( 14 ). As will be explained hereinafter, the trailing edges ( 37 A) may be tapered to minimize buildup of powder from the tablets. When the rotor is rotated clockwise in the direction of the arrow, the leading or cutting edge ( 37 ) will cause powder from the tablet to collect below the top of the rib and shift to the right to the end point ( 38 ). As the powder leaves the end point ( 38 ) of the rib ( 37 ), it soon engages the next leading edge ( 37 ) of the companion rib ( 37 ) and is then shifted to the right until it either slips by the end ( 38 ) or is deposited in the discharge chute ( 19 ). It will be understood that the rotor assembly ( 13 ) may be injection molded and is preferably made as a hollow cylindrical form in which the shaving means ( 36 ) is an imperforate part of the cylindrical. Thus any powder that is sliced from a tablet is shifted to the left and back to the right and to the left and back to the right until it is discharged in the discharge chute ( 19 ) as is clearly shown in FIGS. 1 through 3 . [0042] Refer now to FIG. 5 showing another form of dual rib shaving means. The leading edges of this dual spiral rib configuration tend to trap powder in the crotch of the V shown in the center of the shaving means ( 36 ). However, the nature of this device tends to move the powder shaved from the tablets towards the center of the discharge chute ( 19 ) and has been found to be an effective shaving means for most tablets. When used in conjunction with the cleaning brushes and combs to be described hereinafter, this dual rib configuration is extremely effective and when used in conjunction with tapered trailing edges of the ribs little or no residue is accumulated even without the cleaning brushes. Rotors made from hard glass-like finish plastic do not tend to clog. [0043] Refer now to FIG. 6 showing a singular helical rib ( 39 ) having leading cutting edges ( 37 ) and tapered trailing edges ( 41 ). While this single helical rib is extremely effective in slicing tablets by removing portions at no more than the height H of the rib ( 39 ), it tends to move the powder to the right and traps powder against the side of the rib ( 39 ) which engages the right most bearing ( 33 A), however, deposits which form in this V shaped cavity can be easily removed by a resilient brush ( 41 ) which cleans the cavities below the tops of the ribs when properly inserted in the brush recess ( 24 ) shown in FIG. 1 . It will be understood that the brush 41 may be replaced with a resilient comb ( 42 ) or resilient comb shaped brush ( 42 ) as the case may be. [0044] Refer now to FIG. 7 showing a front view of a motorized version of the decomposing apparatus shown in FIGS. 1 to 6 . The major modification required for simplification or a motorized version is to change the axial direction of the shaving means ( 36 ) by 90 degrees so that the shaft ( 42 ) of the motor ( 43 ) in housing ( 44 ) can directly couple to the rotor means ( 13 A, 36 ) thus replacing the need for a crank arm. The motor ( 43 ) is preferably driven by a rechargeable battery pack ( 45 ). In the preferred embodiment of the motorized version an actuation switch ( 46 ) is provided in the thumb area and completely clear of the pressor foot assembly ( 12 A) (not shown). It will be appreciated that the rotor assembly ( 13 A) may be provided with a cap having an anti-friction flange ( 31 ) which is adapted to hold the rotor assembly in place against the housing ( 44 ) and may be inserted in the housing assembly from the flange ( 31 ) end to engage a spline or recess in the shaft ( 42 ). The side walls ( 14 B) of the hopper are shown having a taper, thus, the pressor foot (not shown) is provided with a similar taper and cylindrical shape so as to engage firmly against the slicing or cutting ribs of the rotor. [0045] Refer now to FIG. 8 showing an enlarge schematic view of a continuous spiral slicing rib ( 39 ) of a rotor assembly ( 13 ) mounted in a housing assembly ( 11 ) and having a curved pressor foot ( 17 ) engaging a tablet ( 47 ) between the pressor foot and the rotor surface ( 48 ). The force of the pressor foot ( 17 ) is seldom great enough to permit the leading edge ( 37 ) of the rib ( 39 ) to make a slice from the tablet ( 47 ) which is as thick as the height H of the rib ( 39 ). This is to say that the slicing action of the leading edge ( 37 ) actually shaves portions from the tablet ( 47 ) which never exceed the height H. The tablet ( 47 ) is urged by the inclined or helical direction of the rib ( 39 ) into engagement with a side of the housing ( 11 ) as shown. As portions of the tablet ( 47 ) are shaved or removed, the force of the pressor foot ( 17 ) will eventually cause the tablet to be crushed or fractured which further enhances the powdering and decomposition procedure even if the tablet has not been pre-fractured using the prefracturing means ( 15 , 16 ) described hereinbefore. It will be appreciated that the diagonal or helical direction of the cutting edge ( 37 ) enhances the shaving action and reduces the force required to rotate the rotor, however, various forms of ribs have been considered. A horizontal rib or protrusion provided on the rotor ( 13 ) is not as effective as a helical shape. If the ribs are placed too close together then the tablet ( 47 ) does not have adequate space to drop between the helical ribs and perform the desirable shaving action. Other forms and shapes of ribs are operable but are not as effective as the helical shape described herein as the preferred embodiment of the present invention. [0046] It will be appreciated that for the presently preferred embodiment, the universally standard patient's cup ( 21 ) fits so tightly against the bottom surface ( 22 ) that substantially no spillage will occur even when the apparatus is accidentally dropped after decomposing a tablet. In the preferred embodiment of the present invention it was found that the height H of the slicing rib ( 39 ) when made approximately 1/30th of an inch produced the best results. [0047] A feature of the present invention is that it may be made for right handed persons or left handed persons by reversing the rotor assembly in the standard housing. Unlike prior art devices, improved apparatus ( 10 ) may be configured easily by a user by removing improved end cap ( 50 ). As described above, by applying a pinching force to opposed pinching surfaces ( 58 ), gap ( 56 ) is collapsed in some degree thereby disassociating latching surface ( 56 ) from rotor assembly ( 13 ) allowing end cap ( 50 ) to be removed from apparatus ( 10 ) without the use of removal tools. Once end cap ( 50 ) has been removed, rotor assembly ( ) may be removed from a first side of apparatus ( 10 ) and inserted into a second side of apparatus ( 10 ). Once rotor assembly ( 13 ) has been reinserted into housing ( 11 ), end cap ( 50 ) is snapped into recess ( 32 ) thereby securing rotor assembly ( 13 ) at least partially within housing ( 11 ). [0048] It should be appreciated that a blade ( 39 ) comprising a reverse helical shape may be used so that the leading edge cuts in the direction in which the left handed or right handed model would ordinarily be turned. Further, the motorized version shown in FIG. 7 has been made so that the rotor-shaving means is completely removable as a unit and may be cleaned and reused by standard cleaning and/or sterilization procedures. [0049] While the novel decomposing apparatus was designed to reduce compressed tablets to a powder of a predetermined size it has been used to decompose peppercorns and coffee beans, thus, has a desirable secondary use for powdering hard and semi-hard condiments and food items. Powdered custom blend coffee may be deposited directly into a filter paper holder of the type used for a single cup of coffee made in a microwave oven or a larger filter of the type used in coffee machines. Thus, the preamble of the claims is not intended to restrict the claims to the preferred mode of use. [0050] While the present subject matter has been described in detail with respect to specific embodiments thereof, it will be appreciated that those skilled in the art, upon attaining an understanding of the foregoing may readily adapt the present technology for alterations to, variations of, and equivalents to such embodiments. Accordingly, the scope of the present disclosure is by way of example rather than by way of limitation, and the subject disclosure does not preclude inclusion of such modifications, variations, and/or additions to the present subject matter as would be readily apparent to one of ordinary skill in the art.

4y

TECHNICAL FIELD This invention relates to the manufacture of insulated members and particularly to a method and apparatus for insulating the generally annular space between a core pipe and a casing pipe as an operation in the manufacture of insulated fluid conduits. While the principles of the invention will be explained in relation to the construction of such conduit, it will be understood that these principles are applicable to the insulating of other hollow articles. More particularly, this invention relates to the placement of a foamable, curable material, usually an organic polymer, which ultimately results in a low density, rigid, foamed material when cured. BACKGROUND OF THE PRIOR ART In the past, an insulated conduit has been made by constructing a pipe section comprising a core pipe, a casing pipe positioned generally coaxially around or at least aligned with the axis of core pipe, and appropriate material between the core pipe and the casing pipe to thermally insulate the core pipe, and means to permit the connection of the pipe section to other similar sections. The insulating material, generally a foamable polyurethane material is placed in the generally annular space between the core pipe and the casing pipe. This placement is done by positioning the core pipe within the casing pipe by the use of end plugs and, if necessary, a rigid spacer in the annular space somewhere approximate the center of the pipe section. The core pipe and casing pipe were angled at approximately 15° to the horizontal. A source of the foamable, curable urethane material was connected to a flexible hose and this hose is introduced into the space. The material, in an activated but un-foamed (liquid) condition was conducted down the hose to the annular space and flowed down the pipe to a point approximate the end of the casing remote from the upper end thereof. As the material reacts, it foams, expands and flows along the axis of the elongated space and up the distance defined by the casing and the core pipe, substantially filling the elongated space. The reacting urethane becomes relatively rigid and encapsulates inumerable small gas bubbles to insulate the core pipe. Because the pipe section must be of substantial length (up to 10' to 20' or more in total longitudinal dimension) a number of problems arise from this method. Because of the distance that the material must be conducted, various parameters well known in the polymer foaming art must be adjusted to delay the reacting and foaming in order to permit the material to be deposited in the pipe before the material begins to react and foam. This delay prevents the clogging of the hose used to introduce this material and also, prevents the material from foaming up and "blocking" a portion of the space, thus entrapping a portion of air and creating a void in the insulating layer of the cured, foamed material. While pouring and foaming the insulating material in the manner described above reduces condierably the void creating problems, it often increases material usage. It was found that when an adequate amount of material was placed towards the lower end of the sloping pipe, hydrostatic pressure and slowed reaction time prevented the material from fully expanding to its optimum density during the foaming operation. This hydrostatic pressure was a result of both the fluid "head" created over a portion of the material by the mass of unfoamed/foaming material, as well as the tendency of the material to become highly viscous during its expanding process, thus limiting the degree to which the underlying foaming material could expand due to sheer forces between the viscous material and the pipe wall surfaces. Attempts to increase the rate of foaming reaction of the insulating material, and thus increase the tendency of the foam to fully expand, resulted in generating compressive forces and high exothermic reaction temperatures on the interior pipe which, if the interior pipe was made of a thermoplastic (specifically PVC), led to undue heating and subsequent collapse of the core pipe. Reducing the angle of the pipe relative to the horizontal would tend to reduce the "head" over the expanding material, and thus reduce the hydrostatic pressure and permit greater expansion. However, this would precipitate entrapping air pockets and result in the creation of cavities in the insulating material and concommitant reduction in the insulating value provided thereby. BRIEF SUMMARY OF THE INVENTION Accordingly, the present invention includes apparatus for placing insulating material around a core pipe which is axially aligned and surrounded with a casing pipe. This core pipe and casing pipe thus define an elongated space of generally annular cross section. The method comprises introducing, from a position remote from the space a source of insulating material in a flowable form, disseminating this material from the source into the elongated space adjacent this source. While continuing to disseminate this material, the source is moved relative to said elongated space along the axis thereof whereby to create a moving front of insulating material. Said front moves along the axis and presents a surface facing the direction of movement of this front such that the material accumulates at the surface of this front to substantially fill the elongated space and substantially exclude voids created by pockets of gas entrapped in the space by the insulating material. Preferably, this material comprises a curable foamable insulating material such as polyurethane foam. Also disclosed is apparatus of placing a layer of foamable settable material between at least a pair of horizontally extending spaced opposed surfaces. These surfaces are closely spaced to one another relative to their horizontal extent. This use of the inventive apparatus comprises introducing, from a position remote from a first portion of these opposed surfaces, a source of the foamable settable material in an unset unfoamed flowable condition. This material is disseminated from the source. With this dissemination, the foaming of this material is initiated whereby said the material expands during the foaming to substantially fill a portion of the space between these opposed surfaces. The source is moved relative to the surfaces during the foaming to create a moving foam front which presents a substantial surface facing the direction of the movement of this source. The distance between the surface of the foam front and the source of material is controlled while disseminating this material such that the material expands behind the foam front to substantially exclude voids created by pockets of air entrapped in the space between the surfaces and the expanding material. Also disclosed is an apparatus for placing a foamable, curable material in a space defined between a core pipe and an axially aligned casing pipe comprising a reservoir remote from this space. This reservoir provides the constituents of the material. This apparatus further comprises means for separately conducting these constituents to the space from the reservoir and means for disseminating this material within said space. This last mentioned means further includes means for intimately mixing the constituents separately conducted thereto substantially simulataneously with the disseminating of the material into the space. BRIEF DESCRIPTION OF THE DRAWINGS FIGS. 1A, 1B and 1C illustrate the method of placing the insulating material in accordance with Applicants' invention; FIG. 2 is a schematic showing of the preferred apparatus for performing the method illustrated in FIG. 1; and FIG. 3 is a cross-sectional view of a portion of Applicants' preferred embodiment. DETAILED DESCRIPTION OF THE INVENTION Turning to the drawings with particular reference to FIGS. 1A, 1B, and 1C, a typical arrangement for a factory or field insulated conduit is shown by reference numeral 10. Generally, conduit 10, as is typical, comprises a casing pipe 12 which surrounds core pipe 14 (which in the preferred embodiment is a single pipe) which is arranged to extend longitudinally along and aligned with the axis of casing pipe 12. It should be understood, of course, that conduit 10 could comprise one or a number of core pipes surrounded by a single casing pipe 12. In such a system, two or more pipes 14 are aligned with but are spaced in varying relations to the axis of pipe 12. Casing pipe 12 and core pipe 14 thus define between their respective inner and outer surfaces an elongated space 16 of generally annular cross-section. This space extends the full length of insulated conduit 10, except, of course, for end plugs or connecting means associated with the terminal ends thereof. However, a conduit 10 may or may not include such ends plugs in the preferred use of Applicants' inventive concept. An example of such a conduit is shown is in U.S. Pat. No. 3,492,029 assigned to the Assignee of the present application. In this particular conduit, end plugs are indeed provided. In the alternative, tooling may be provided to act as molding surfaces for the subsequently applied insulating layer thus eliminating the need for such end plugs. Means for disseminating insulating material comprising insulating probe 20 is shown in operative position within the to-be-insulated conduit 10. Probe 20 comprises at its distal or remote end a mix head 22 which functions as a source of the insulating material to be placed in the annular space 16. Connecting mix head 22 with a plurality of feed lines 24 (FIG. 2) is elongated means 26 which connects to actuator 28, which in turn operates mix head 22 as will be further disclosed. Also associated with mix head 22 are centering guides 30. In operation, insulating probe 20 is moved axially relative to conduit 10, either manually or automatically. This in turn moves mix head 22 generally axially along the longitudinal axis of elongated annular space 16. Conversely, of course, conduit 10 and thus the opposed closely spaced surfaces of 12 and 14 may be moved axially relative to probe 20 in order to bring about the relative movement between mix head 22 and the elongated annular space 16 defined between these surfaces. FIG. 1b and 1c show this relative movement and the substantially simultaneous dissemination of insulating material M in flowable form from mix head 22. For reasons that will become apparent, Applicants prefer to use a particular insulating system which employs the use of separate constituents which are mixed together. This mixing initiates the reaction and subsequent foaming and curing of the material. Accordingly, Applicants prefer a known system employing isocyanate and urethane resin components. These materials are mixed intimately by mix head 22 and initiate the foaming reaction to react and form the insulating material. The overall insulating material mixing and dispensing system is shown schematically in FIG. 2. Probe 20 is shown attached to flexible high pressure feed lines 24 which in turn are connected to a high pressure dispensing machine 130 and associated resin and isocyanate reservoirs 132. While any number of commercially available dispensing systems would be adaptable to Applicants' invention, Applicants prefer to use the systems disclosed in U.S. Pat. Nos. 3,765,605 and 3,627,275, which patents are hereby incorporated by reference. The dispensing system disclosed in the above-referenced patents, as well as other similar systems available commercially, dispense precisely metered amounts of active components at relatively high pressures. These components are combined in a manner to intimately intermix these components. This intermixing initiates the curing reaction. The dispensing from high pressure permits gases, either dissolved in one or both of the reactants or which result in a chemical reaction initiated by the mixing, to begin to expand and thus form gas bubbles throughout the liquid or semi-liquid reacting polymer mass. Because of the unique operation necessitated by Applicants' inventive insulating method, mix head 22 has very small vertical dimension to permit its installation between the opposed, facing surfaces of core pipe 14 and casing pipe 12. This dimensional restriction has led to the separation from the mix head 22 itself from the actuator 28. This physical separation is made possible by the provision of an elongated member 26 which has a longitudinal dimension adequate to place mix head 22 adjacent a first portion of the opposed surfaces which define the remote end of annular space 16 of the longest pipe section which is anticipated to be insulated. The preferred embodiment this dimension is about 20 feet (6 meters). Means 26 includes high pressure conduits 26a and 26b which are preferably constructed of a rigid stainless steel to provide thickness and rigidity necessary to maintain mix head 20 at a fixed distance from the actuator 28. Means 26 further includes valving rod 26c which is moved by actuator 28 a controllable axial distance to displace the end thereof positioned within mix head 22 to controllably and simultaneously mix the components provided via 26a and 26b and disseminate the resulting material. Depending upon the particular chemical system employed, conduits 26a and 26b may include electrical heater tapes in order to condition the chemical constituents passing therethrough and provide these constituents to mix head 22 in optimum condition for mixing, disseminating, foaming and curing thereof to form the insulating material. FIG. 3 shows a partial cross-section of mix head 22 showing the flow paths of the isocyanate and resin constituents to a valving and impinger assembly associated with the end of valving rod 26c. While other disseminating and mixing systems may be employed, Applicants prefer the system shown in FIG. 3, the basic principles of which are set forth in further detail in U.S. Pat. No. 3,876,145, which patent is hereby incorporated by reference. Other systems having labyrinth path type of mixing may be employed however. A system of high pressure mixing as shown in U.S. Pat. No. 3,263,928 may also be used as a substitute of the particular arrangement shown in FIG. 3. In general, the mix head 22 shown in FIG. 3 has the characteristics of mixing of the constituents and thus initiating the subsequent foaming and curing of the material disseminated therefrom simultaneously with that dissemination. Mix head 22 consists of two major components, mix head block 22a and valve block 22b which in the operative condition are fixedly attached to one another via bolt or bolts (not shown) accessible from the rear end of valve block 22b. Sealing gaskets 122 seal the flow paths of the components passing through 26a and 26b to the respective portions of mix head block 22a. The flow path of each of the components through value block 22b are generally identical, so for simplicity, the flow path of second component only will be outlined in detail. This can be seen in the lower portion of FIG. 3 elongated conduit 26a is attached to the rear portion of valve block 22b. Disconnect valve 124 can be operated by rotation of valve member 125 positioned therein to prevent loss of component from the flow channel defined therein when valve block 22b is disconnected from mix head block 22a. Component passes through filter screen 126 past check valve 128 to component channel 222. It should be noted that component channel 222 is parallel to the axial direction of elongated operating rod 26c. This parallel orientation is consistant with the flow channels passing through valve block 22b and contributes to the overall compact arrangement of mix head 22. From component channel 222 the material passes to component impinger 224. The flow channels through mix head 22 connected to component conduit 26b is generally identical to that set forth above, except of course that first component channel 226 terminates at first component impinger 228 rather than continuing forward of throat 229. This arrangement also contributes to the overall compact arrangement of mix head 22 and leads the first component contained in this flow channel to the throat 229. The operation of valve rod 225 and its relation to throat 229 and operation thereof is set forth in greater detail in U.S. Pat. No. 3,876,145 mentioned supra. Thus mix head 22, as the source of the insulating material, is positioned within space 16 and adjacent to the ultimate position of the material disseminated thereby. This close proximity or adjacency permits the employing of a chemical foaming system which has a quicker reaction time (in terms of cream time and foam time, as well as tack free time) than that employed in the prior art insulating system set forth above. The parameters controlling of such a quick reaction time chemical foam system are well known in the art. These parameter include the amount of catalyst addition, constituent selection, blowing agent, and temperature at which the materials are mixed and maintained, all of which contribute to the rate at which the disseminated material begins to foam and rise to substantially its fully foamed condition. Referring again to FIGS. 1a, 1b and 1c, the operation of the disclosed system will now be set forth. With casing pipe 12 and core pipe 14 axially aligned and substantially horizontally oriented as shown, probe 20 is moved relative thereto to bring mixing head 22 approximate to the remote end of space 16. In the preferred embodiment, mix head 22 has a vertical dimension is equal to or less than the distance between the inner wall of casing pipe 12 and outer wall of core pipe 14. In this manner, the mixing head can itself provides a local support for core pipe 14 and thus comprises means for at least partially maintaining the surfaces of pipes 12 and 14 in controlled relationship with one another. To this end, Applicants prefer to install mixing head 22 below core pipe 14 in order to counteract the tendency of gravity to cause core pipe 14 to sag. It should be understood, of course, that some means other than mix head 22 may be employed to be associated with mix head 22 to support the pipe if it is found desirable to disseminate the material from a position other than below core pipe 14. In order to aid mix head 22 in this support function, support guides 30 are pivotally attached thereto. These are positioned in cavity 16 and in contact with the outer surface of core pipe 14 and/or the inner surface of casing pipe 12 at positions lateral to mix head 22. Thus rollers 30 and mix head 22 form an adjustable U-shaped support means which conformably wraps around at least the lower-portion of pipe 14. The dissemination, and thus the initiation of the foaming and curing reaction is performed from the position shown in FIG. 1a. In practice, the initial distance between the end of space 16 (defined by either an end plug or a mold surface of appropriate tooling) and the discharge tip of mix head 22 has been found to be between 2 feet and 4 feet. The material M in liquid form sprays onto the end plug or mold surface (not shown) and the facing surfaces of core pipe 14 and casing pipe 12. After an adequate amount of material M has been disseminated the probe 20, mix head 22 begins a controlled withdrawal from space 16 while continuing to disseminate material M. The first portion of material M begins to react and the gas material disposed or created therein begins to expand to form a mass of rising foam M 1 . While a majority of the material in the preferred embodiment is placed in the lower quadrant of the annular cross-section of 16, the material in the liquid or semi-liquid state during this initial rise envelopes core pipe 14 around the entire circumference thereof. This initial rise is substantially unimpeded since additional material placed in front of M 1 has yet to substantially react and is thus not in a condition to block the free expansion of the gas bubbles. Also, in contrast with the above-disclosed prior art method, the hydrostatic "head" on material M, in any stage of foaming can be no more than the diameter of the inside surface of casing pipe 12 which, when compared to the longitudinal length of cavity 16, is minimal. This illustrates one of the many advantages of placing material M along a substantially horizontal axis as is being described. FIG. 1b shows liquid material M 2 which has been subsequently placed in the lower quadrant of space 16 and initially placed material M 1 having foamed substantially completely around core pipe 14. From this point on the reacting and foaming material M 1 creates a foam front which, because of the continuing reaction and foaming of the material M 1 as well as the continuing placement of further material M 2 in liquid form thereon, moves at a controllable rate along the axis of conduit 10. This foam front F is defined in part by a surface or interface between the placed material and the air in cavity 16 which the foaming and fully foamed material M 1 is progressively displacing. Because of this continual placement and renewal of material in liquid form onto and about that foam front, surface S thereof faces the direction of movement of the foam front F along the axis of conduit 10. It should be understood that this surface S is usually something other than a flat surface which faces directly along the axis of conduit 10. On the contrary, it is likely that this surface is of irregular nature which can be approximated by a plane P, angled to the axis of conduit 10. This angularity is in part due to the placement of the majority of the material in the lower quadrant of space 16 and also due to the tendency of the foaming and reacting material, in its semi-liquid state, to remain in the lower quadrant due to gravity. FIG. 1b shows surface S and this imaginary plane P, generally parallel to the overall surface S. It has been found desirable to maintain surface S, using the parameters set forth above, such that plane P defined thereby forms an angle "a" to an imaginary horizontal plane containing longitudinal axis A of between about 165° and about 90°. Axis A is not only the axis of pipes 12 and 14, but also the axis of elongated space 16 and hence the direction of movement of both the withdrawing mix head 22 and foam front F. The creation of foam front F results in considerable benefit. First of all, it substantially prevents the entrapment or inclusion of pockets of air within the volume of reacting material, thus reducing substantially the tendency to create cavities in the final cured insulating layer. Secondly, the foam front F and its maintenance by the dissemination of material M from mix head 22 automatically classifies the material M as to its various stages of foaming and curing. The more fully foamed material pushes ahead of it the less cured, more liquid (thus less fully expanded) material, thus eliminating the tendency of a more fully reacted material to block the expansion of this less fully expanded liquid material which may become trapped therebehind. The creation and maintenance of the foam front F is, because of the relationship of the mix head 22 and surface S, substantially independent of the orientation of and direction of progress of the filling of space 16. The horizontal mode of filling, however, is preferred since this orientation minimizes restricting the foaming and expansion of the material M, and also eliminates the handling problems associated with tilting conduits of very long dimensions. FIG. 1c shows the operation of probe 20 and shows the portion M 1 of the foam material M having reacted and cured to the point where it becomes essentially self-supporting. At this stage the material M 1 can contribute to the supporting of core pipe 14 and hence to the maintenance of the space between the opposed surfaces of core pipe 14 and casing pipe 12. In this way, core pipe 14, despite its tendency to sag is held in approximately its previously supported, centered position by the cured portions M 1 of material M. This supporting function of material M 1 works in conjunction with the vertical support provided by the terminal end of insulating probe 20 (either directly on mix head 22 or associated support means such as guides 30) and works to eliminate the need for providing space 16 with spacers or permanently fixed centering members. An example of the use of Applicants' disclosed method and apparatus will now be set forth. A conduit 10 having an overall length of about 6 meters is positioned horizontally. A core pipe 14 made of PVC and having an outside diameter of about 6 cm is positioned coaxially with casing pipe 12 of PVC and an internal diameter of 15.5 cm. These two pipes are held immobile relative to one another during the foaming operation. An end plug, in accordance with U.S. Pat. No. 3,492,029 is positioned in the remote end thereof. Insulating probe 20 with mix head 22 having a vertical dimension of about 2.5 cm is introduced beneath core pipe 14 and supports the flexible core pipe 14 slightly vertically above its precise axially centered position. Probe 22 is moved to within about 1.5 meters of the end plug (not shown). Isocyanate and resin of known chemistry and is provided to mix head 22 at 110° F. and 800 PSI. Actuator 28 withdraws valving rod 225 via 26c to intimately intermix the constituents provided via 26 a and 26b and thus initiating the curing, foaming and disseminating material M at the rate of about 6.8 K g /min from the mix head 22 into the portion of space 16 adjacent thereto and onto the inner surface of the end plug and opposed surfaces of 12 and 14. After about 10 seconds of this, mix head 22 is withdrawn from space 16 at the rate of 25 cm per second while continuing to disseminate material M at the above rate. Foam front F moves at approximately the same rate towards withdrawing probe and associated mix head 22 and is maintained at approximately 1.25 M from mix head during the withdrawal thereof. Foam front F presents surface S facing the direction of movement of foam front having a defining plane P, at an average angle "a" of about 135° to the horizontal plane cotaining axis A. The probe continues to be withdrawn and continues to disseminate material until approximately 50 cm from the open end of cavity 16. Actuator 28 is operated to move valving rod 225 forward and terminate the dissemination, mixing and initiation of material M. The mixing head 22 is now fully withdrawn and an end plug or appropriate mold surface is forced into the open end of space 16. Material M continues to react, foam and expand to fill completely the space 16. Finally, material M is permitted to fully cure. The polyurethane foaming system preferred by Applicants is one in which the cream time associated therewith is 0.1 to 0.5 seconds, the rise time is 10 to 15 seconds and the tack free time is 10 to 15 seconds. While considerable variation can take place as to each of these parameters, the above times are a guide in order to permit the full utilization of all the benefits of Applicants' invention. For example, the tack free time could be delayed for various reasons. This parameter is only important if the material making up core pipe 14 is one which requires that the fully foamed material M support a substantial portion of its weight and prevent its sagging due to gravity. If this aspect is not important, then tack free time can be delayed in order to reduce the overall temperature rise caused by the reacting foam chemistry. While Applicants have described their method and apparatus in terms of a polyurethane foam system, it should be understood that other systems embracing an insulating material having a fluid state could be used. For example, an insulating system comprising essentially dry materials which are made flowable by combining with air (for example, fiber glass blowing wool) could be used. In this case, mix head 22 would disseminate and mix a settable binder and chopped fiber glass which would, as the fiber glass accumulates, create a "front" similar to the above described "foam front" at a rate corresponding to the rate which the mix head 22 is withdrawn from the cavity. Other settable materials such as a syntactic foam comprising a reactable binding material and glass or perlite microspheres may also be employed where structural characteristics of such material are desired. In such case, the "foam front" would move along the longitudinal axis of cavity or space 16 primarily in response to the accretion of the materials as they are sprayed onto the previously deposited material by mix head 22. Hence, in contrast with the above-disclosed polyurethane foaming system, movement of the foam front F would not result from the further expansion of gas bubbles behind the surface presented by foam front F. Again, in such a system, the withdrawal of mix head 22 would be controlled to correspond with the accretion of the materials at the foam front F. Also, it may be desirable to disseminate the material M from mix head 22 in an intermittent fashion rather than continuously along the longitudinal axis of space 16 as set forth supra. In such case, material M would be disseminated on the walls and foam front. The material M would be permitted to foam to substantially its fully expanded dimension and cure, at least to the extent necessary to partially support core pipe 14. Then mix head 22 would be withdrawn by a calculated distance and a further amount of material M would be disseminated. Thus, conduit 10 would be insulated in a discrete step-wise fashion. This system would have the advantage of maintaining core pipe 14 in a precisely located, fixed position and would be advantageous where the precise centering of core pipe 14 is more vital than a rapid insulation placement and completion of each section of conduit 10.

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FIELD OF THE INVENTION The invention relates to an energy converting device, especially for conversion of mechanical energy into hydraulic energy and from the hydraulic energy into electrical energy. BACKGROUND OF THE INVENTION Renewable energy resources also include the energy of ocean waves, whose energy potential is estimated to be able to provide roughly 15% of worldwide power demand. Ocean waves inherently constitute a type of ocean movement which is less regular in terms of time and space, but no less energy-rich, such as, for example, the known motion of the tidal range. The technical implementation for obtaining the energy from the ocean can be based on different principles. One possible implementation principle is based on a dual-mass system which floats in water. The two masses are used. As a result of the natural frequencies which are distinctly different from one another, the masses have different relative motions with respect to one another due to wave motion. These relative motions of the masses with respect to one another can be converted into pump motions of working cylinders, such as hydraulic cylinders, to then obtain, for example, by a generator, electrical energy. The hydraulic energy converts into usable current by the working cylinder, caused by mechanical energy in the form of wave motion. DE 601 15 509 T2 discloses a pertinent, point-absorbing wave energy converting device for obtaining energy from wave motion on the surface of a body of liquid and with dimensions which are small compared to the wavelength of the predominant wave. The known solution has two devices which can move in relative terms opposite one another as two movable individual masses. The first device has a float. The second device has a submerged body underneath the surface of the body of liquid. Hydraulic working cylinders between these two mass devices execute lifting motions for energy transfer from mechanical into electrical energy due to the relative motion of the individual masses with respect to one another caused by the wave motion. In these dual-mass systems which float in water, often a time offset is between the wave motion and the guided motion of at least one of the masses of the dual-mass system, with the result that mass motion can be stopped or at least decelerated. This time offset, for example, when the amplitude of the wave after passing through the wave trough rises again, while at least one of the two masses following in time is still in downward motion in the direction of the wave trough and then is slowed down or even stopped in this motion by the already rising wave. The energy conversion is adversely affected or even stopped by this “retarding moment.” To counteract these failure phenomena, PCT-WO 2005/069824 A2 describes an energy converting device which makes it possible, with inclusion of the corresponding sensor technology, to briefly switch over a generator for current generation, caused by the wave motion, and a corresponding mechanical converter segment in the form of a rack and pinion drive, into motor operation. At least some of the energy obtained beforehand can then be used again to drive a mass which has been set in the direction of standstill dictated by the wave motion, such that the indicated dead point phases are overcome. Depending on the actual circumstances of the wave motion, the energy converting device can then be used either as a generator in the energy recovery mode or in motor operation as a driving control force for the respective mass of the energy converting device to ensure a basic situation of motion from which the mass can be moved more easily by the wave than if it assumes a decelerated state or even a rest state. In spite of the energy yield which is improved in this way, however, for driving the mass out of the respective wave dead point zone, energy is lost again in the motor operation of the device. Overall, this loss reduces the possible energy yield. The magnitude, height, and frequency of wave motion are highly variable, as are the absolute values of the magnitudes of motion as well as the pertinent relative value of the body excited by it in the form of the individual movable masses. Due to the variable behavior of the wave motion, in practice the conversion of the mechanical energy associated with it into electrical energy poses problems, in the sense that uniform current delivery is not achieved, and/or as a result of feedback processes the “mechanical wave machine” is stopped by the respective working cylinders being stopped or at least greatly decelerated in their motion. SUMMARY OF THE INVENTION An object of the invention is to provide an improved energy converting device which is almost free of feedback and which can convert different forms of energy into one another with very good yield. This object is basically achieved by an energy converting device according to the invention that uses as the energy transport medium a control fluid which is routed in two different control circuits which are dynamically connected to one another for energy transfer by a coupling device. One control circuit is used for energy supply, especially in the form of mechanical energy. The other control circuit is used for energy delivery in the form of converted energy, specifically electrical energy. By division into two different control circuits, the coupling device located between the circuits can be operated such that energy feed in one control circuit is separated from energy delivery in the other control circuit, at least to the extent that in their operation they do not mutually disrupt one another. Adverse feedback effects, particularly in the direction of energy feed for the converting device, are then reliably avoided. Surprisingly for one with average skill in the art in the field of energy conversion in spite of using a coupling device requiring for its operation some of the energy to be converted, one arrives at improved energy transmission results in conversion. In particular, improved uniform delivery of electrical energy to the connected consumers, even in the form of battery ampere-hour capacities is also achieved. The converting device can also be economically implemented with its components and is reliable in use. The energy converting device according to the invention need not be limited to use in wave energy systems. A host of possible applications is conceivable for example, in the field of wind power plants, in which mechanical rotor motions are to be converted into electrical current, with comparable problems as indicated above. The energy conversion chain can also be reversed in the sense that, for example, basic electrical energy is converted into mechanical energy without feedback using hydraulic energy as the intermediate medium. In one preferred embodiment of the energy converting device according to the invention, the coupling device has a hydraulic motor connected to one control circuit by a gear connection with a definable transmission ratio, which can even be 1:1. The motor drives a first hydraulic pump with a variable stroke volume, which pump is connected to the other control circuit. As a result of the variable stroke volume of the hydraulic pump, the pump is driven by the hydraulic motor only to the extent that, caused by the wave energy, the control fluid as an energy transport medium in this case can also deliver energy. Specifically, the energy-delivering control circuit is adjusted in terms of its output performance according to the wave-mass model. In a corresponding manner, in one preferred embodiment, energy delivery and energy transport in the second control circuit are then controlled by a hydraulic motor with a triggerable, variable stroke volume. Other objects, advantages and salient features of the present invention will become apparent from the following detailed description, which, taken in conjunction with the annexed drawings, disclose a preferred embodiment of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS Referring to the drawings which form a part of this disclosure and which are schematic and not scale: FIG. 1 is a side elevational view of the fundamental structure of a converting device for converting mechanical wave energy into hydraulic energy according to an exemplary embodiment of the invention; FIG. 2 is a work diagram of the respective work capacity of the converting device of FIG. 1 , plotted in a force-path diagram; FIGS. 3 and 4 are hydraulic circuit diagrams of energy converting device, including the converting unit, of FIG. 1 , divided along an imaginary intersection line S-S into two component figures with different scales; FIG. 5 is a schematic hydraulic diagram combining FIGS. 3 and 4 . DETAILED DESCRIPTION OF THE INVENTION The converting unit 10 in FIG. 1 , is made in the form of a floating buoy and, in addition to a post float ( 12 ), has a toroidal or ring float 14 . As a result of different natural frequencies, depending on the excitation, the two bodies execute relative motion. The different mass motion which accompanies different wave motion is relayed to a displacer device 18 of individual hydraulic working cylinders 19 connected on their piston side to the post float 12 and on their rod side to the ring float 14 . This converting unit 10 , is shown by example in FIG. 3 in a control diagram as a spring-mass oscillator with the corresponding cushioning element, wave passage being detected by way of example according to path (x-wave) and speed (v-wave) as a cumulative input signal in a symbolically depicted block diagram 20 . As a result of the different motions of the post float 12 with respect to the ring float 14 , for the displacer device 18 , a pumping motion of the individual hydraulic working cylinders 19 occurs. The hydraulic energy obtained thereby can in principle be supplied to a hydraulic motor which could directly drive a generator for producing electrical energy. This direct drive, however, leads to the aforementioned feedback and stability problems. Fundamentally, the following formula relationships apply: Energy: W=∫F·ds Power: dW/dt=F·v dW/dt=p·A·v On the one hand, the force F of a cylinder 19 is proportional to the pressure p which acts on its piston surface and which is produced by the load resulting from the opposite relative motion between the post float 12 and the ring float 14 . On the other hand, the power which can be obtained from the wave energy by the opposite relative motions of the masses M 1 and M 2 depends on various factors, particularly on the energy content of the partners involved. The determining factors are the selected mass and the individual speeds achieved. If, for example, the actuating pistons of the individual cylinders 19 can be pumped almost without force, then as shown in FIG. 2 , a maximum stroke is produced, but the pressure which can be generated is almost zero, and the power and the energy which can be obtained therefrom are close to zero. This curve characteristic is designated as 22 in FIG. 2 . The pressure is maximum due to the very high or excessive force, but cylinder motion in itself is blocked; i.e., the desired relative motion approaches zero, and likewise the energy which can be produced with it is also close to zero. This situation is qualitatively designated as 24 in the diagram as a curve characteristic, as shown in FIG. 2 . The maximum possible energy recovery therefore lies between these two extremes, i.e., at an average force on the piston of the cylinder 19 which allows a sufficiently large relative stroke. This average force only moderately reduces the motion not being constant, but rather arising as a function of relative velocity when the energy content of the wave is to be used as optimally as possible. The effect of this operation is that the force, like the relative velocity, must change during a stroke, with the pertinently optimum energy curve 26 being produced as an average between the extreme curves 22 and 24 (cf. FIG. 2 ). As a result of this actual wave model, meaningful energy withdrawal in the form of electrical energy using a hydraulic motor connected directly to the control circuit in addition to a generator would hardly make sense. Feedback or a reaction could lead to shutdown of the wave energy receiving device in the form of the converting unit 10 . The control devices detailed below are designed to be used to essentially ensure the pertinently optimized energy curve 26 in the operation of the converting device. At this point, the energy converting device will be detailed below using the circuit diagram as shown in FIGS. 3 and 4 . FIGS. 3 and 4 along the intersection line S-S and the two nodal points combine to show the converting device as a whole. Division into the two figures with the different scales is done for improved representation. As already described, the energy converting device in this exemplary embodiment is used for conversion of mechanical wave energy into hydraulic energy and from the hydraulic energy into electrical energy. The energy transport medium is a control fluid, especially in the form of a control oil or hydraulic oil. This control fluid is routed in two different control circuits 28 , 30 , with FIG. 3 showing the first control circuit 28 and with FIG. 4 showing the second control circuit 30 . The two control circuits 28 , 30 are dynamically connected to one another specifically by a coupling device 32 used for energy transfer. One or first control circuit 28 is used for energy supply, especially in the form of mechanical wave energy. The other or second control circuit 30 is used to deliver energy in the form of electrical energy obtained from the hydraulic energy. The coupling device 32 has a hydraulic motor 34 connected to the first control circuit 28 to carry fluid. As shown in FIG. 3 , the hydraulic motor 34 is located on the opposite side of the control circuit 28 relative to the converting unit 10 . The hydraulic motor 34 is furthermore connected to a first hydraulic pump 38 by a conventional gear connection 36 with a definable transmission ratio. The pump has an adjustable, variable stroke volume, as shown in FIG. 3 . The gear connection 36 is not, however, critically necessary for the operation of the invention. The pertinent hydraulic pump 38 is connected to the second control circuit 30 to carry fluid and in this respect circulates the control fluid of the second control circuit 30 . As already described, to feed energy into a first control circuit 28 a first converting unit 10 converts the mechanical wave energy into hydraulic energy by the first converting unit 10 actuating the displacer device 18 with the individual hydraulic working cylinders 19 . The respective working cylinders 19 , depending on the direction of motion, pump the fluid in the control circuit 28 back and forth in opposite directions. The control fluid of the first control circuit 28 is therefore supplied by the displacer device 18 in opposite directions to the component circuits 40 , 42 of the first control circuit 28 . To the extent that the component circuits 40 , 42 are addressed here, they also relate to the respective component fluid guidance upstream of a Graetz circuit 44 . The volume of the respective working cylinder 19 displaced, by analogy to electrical engineering, is rectified by the Graetz circuit 44 as a rectifier circuit. The Graetz circuit is implemented by four spring-loaded nonreturn valves 46 as shown in FIG. 3 . Viewed in the direction of FIG. 3 , the upper component circuit 40 connected is a conventional hydraulic accumulator 47 used to compensate for leaks and/or cavitation phenomena and, like the Graetz circuit 44 , is protected by a pressure limitation valve 48 relative to the lower component circuit 42 . The Graetz circuit 44 at least ensures that the hydraulic motor 34 is driven only in one direction. The motor enables hydraulic power delivery from the first control circuit 28 to the second control circuit 30 by the gearing 36 . Altogether the gearing 36 is made in the manner of a hydrostatic transmission. To trigger the hydraulic pump 38 from 0% to 100% delivery volume amount, a first control 50 is used for optimum power removal of the wave energy from the first converting unit 10 . The regulator 52 used is provided with a saturation curve and adjusts the Δp actual value to a definable Δp setpoint value, the Δp actual value resulting from the difference of the pressures in the component circuits 40 , 42 of the first control circuit 28 and the Δp setpoint value following from the Δv value which represents the resulting, changing velocity difference with respect to the relative motion of the masses M 1 and M 2 of the post float 12 and the ring float 14 . It would be possible to include other, sensor-detected characteristics of the converting unit 10 into the control here, such as the distance traversed x or the force applied F, etc. With the illustrated control, the mechanical wave energy present at the time is always optimally converted into hydraulic drive energy for the second control circuit 30 . Based on ambient conditions, a closed system is preferably used here. In an open system also only one pressure sensor P of the hydraulic first control circuit 28 is sufficient to accordingly arrive at an input quantity for the first control 50 . For energy delivery from the other, second control circuit 30 , a second converting unit 54 in FIG. 4 is used to converts hydraulic energy into electrical energy. The second converting unit 54 has another displacement device in the form of a hydraulic motor 56 which drives the generator 58 to produce electrical energy. For this conversion of hydraulic energy into electrical energy, a second control device 60 made in the manner of a slip control ensures optimum power delivery to the electrical network. In particular, the output of the second control device 60 is connected to the hydraulic motor 56 such that its stroke volume can be varied in a controlling manner. The regulator 62 of the second control unit 60 is a PID-regulator with a connected saturation curve. To implement the indicated slip control, among other things the reference quantity is the torque (T) of the generator 68 and its shaft rpm w. With the indicated slip control it is possible to keep the electrical output power of the generator 68 at an optimum output point regardless of the actual power input quantity with respect to the power output of the hydraulic pump 38 with a variable stroke volume. To implement the variable stroke volume of the hydraulic pump 38 and hydraulic motor 56 , an inclined cam plate is conventionally used whose effective degree of tilt can be stipulated by the respective control device. In one especially preferred embodiment, this slip control as shown in FIG. 4 is superimposed by feed-forward control 64 of the hydraulically available power which as the input value picks up by two pressure sensors P the pressure difference Δp in the component circuits of the second control circuit 30 upstream and downstream of the hydraulic pump 56 acting in both actuating directions. This pressure difference Δp is used as an indicator for the available hydraulic energy relative to the second control circuit 30 . The hydraulic motor 56 and the generator 58 are designed for a specific maximum flow rate, which is ultimately dictated by the hydraulic working cylinders 19 of the first displacer device 18 . Otherwise, a system which is made open would also be possible for the two circuits. If the flow rate decreases, for example as a result of smaller wave motion on the first converting unit 10 , to this same extent the control pressure in the second control circuit 30 will also decrease. This driving pressure for the hydraulic motor 56 can then drop to low values such that cavitation occurs, which can lead to shutdown of the entire energy converting device in a reaction. In order to manage this problem, the indicated slip control is superimposed by the above-indicated feed-forward control 64 with the result that, provided the flow rate falls back, the hydraulic motor 56 is triggered such that it also requires only a smaller flow rate. The output power for the generator 68 then decreases, but without shutdown phenomena of the entire converting device occurring. In this case the control 60 , 64 therefore allows setting of the electrical output power of the generator 68 for the most varied wave amplitudes relative to the input side in the form of the first converting unit 10 . The second control circuit 30 can also be provided with a hydraulic accumulator unit 66 for purposes of storing hydraulic energy. The second control circuit 30 is also protected by a pressure limitation valve 68 . The illustrated nonreturn valves 70 of the second circuit are used to ensure that vibrations of the hydraulic circuit cannot occur or that backflow in the wrong direction for the control fluid of the second circuit 30 does not accidentally occur. The solution according to the invention need not be limited to use in wave energy systems, but can also be used, for example, for other energy systems, such as wind power plants and the like. Thus, for example, a hydraulic working pump, which is not detailed, can convert the mechanical energy of the output shaft of a wind power plant accordingly into hydraulic energy of the first control circuit 28 and in this case replace the described hydraulic working cylinder 19 . It would also be possible to make available mechanical energy on the first converting unit 10 with as little loss as possible in the reverse direction to the one shown in FIG. 4 proceeding from the second electrical converting unit 54 in the reverse direction. The above-described exemplary embodiment of an energy converting device fundamentally manages even without a Graetz circuit. In this case, however, the hydraulic pump used can be swiveled in both directions. It then undertakes rectification, and absolute-value generation in the regulator is eliminated. Instead of the sensor information of the relative speed, a volumetric flow sensor in the control circuit 28 or the rotary speed (tachogenerator) of the hydraulic motor 34 can also be analogously used. This arrangement has the advantage that the sensor is not exposed to rough ambient conditions. As already described, for the sake of simplicity FIGS. 3 and 4 show only the open system with a tank. By replacing the tank with another accumulator (not shown) a closed system can be created which is especially advantageous for rough ambient conditions. The accumulator in FIG. 3 can be connected to the second component circuit 42 instead of the illustrated tank in the region of reference number 44 . The corresponding hydraulic accumulator in FIG. 4 would be used instead of the tank shown there between the nonreturn valves 70 and the pressure limitation valve 68 . While one embodiment has been chosen to illustrate the invention, it will be understood by those skilled in the art that various changes and modifications can be made therein without departing from the scope of the invention as defined in the appended claims.

4y

CROSS-REFERENCE TO RELATED APPLICATIONS [0001] This application is a non-provisional application which claims priority from U.S. provisional application No. 61/935,185, filed Feb. 3, 2014. TECHNICAL FIELD/FIELD OF THE DISCLOSURE [0002] The present disclosure relates generally to permanent magnet electric motors, and specifically to the bonding of permanent magnets to a rotor or stator of a permanent magnet electric motor. BACKGROUND OF THE DISCLOSURE [0003] In general, electric motors operate by rotating a rotor relative to a fixed stator by varying the orientation of a magnetic field induced by one or more coils. In some electric motors, both the rotor and stator include coils. In such an induction motor, the magnetic field induced by the stator coils induces current within the rotor coils which, due to Lenz's law, causes a resultant torque on the rotor, thus causing rotation. [0004] In a permanent magnet motor, on the other hand, the rotor includes one or more permanent magnets. The permanent magnets, in attempting to align with the magnetic field induced by the coils in the stator, cause a resultant torque on the rotor. By varying the orientation of the magnetic field, the rotor may thus be caused to rotate. In high-torque permanent magnet motors, multiple permanent magnets may be positioned on the exterior of the rotor (for an internal rotor permanent magnet motor). [0005] While in operation, the components of the permanent magnet motor may heat up in response to, for example, electrical resistance in the stator coils, losses in iron core of stator, induced currents in rotor caused by harmonics, mechanical friction, etc. Because of this increase in heat, the permanent magnets must be bonded to the rotor in such a way that any thermal expansion of the rotor or permanent magnets will not cause the permanent magnets to fracture or separate from the rotor. Additionally, in cases where the permanent magnets are formed by, for example, sintering, the permanent magnets themselves may be relatively brittle. Furthermore, where the permanent magnets are constructed of a material with a different thermal expansion coefficient than the rotor, as is often the case, the thermal expansion of the rotor may cause the permanent magnets to crack. SUMMARY [0006] The present disclosure provides for a method for coupling permanent magnets to a rotor. The method may include providing a rotor body, the rotor body being generally cylindrical in shape, the rotor body having an outer surface; forming a mounting hole in the rotor body, the mounting hole positioned to couple to a threaded connector; providing a permanent magnet, the permanent magnet being generally in the form of an annular section, the concave surface of the permanent magnet having a diameter generally equal to the outer diameter of the rotor body, the permanent magnet having a hole formed therein positioned to receive the threaded connector, the hole having a countersink formed therein at the convex surface of the permanent magnet; positioning the permanent magnet on the outer surface of the rotor body so that the hole of the permanent magnet is in alignment with the mounting hole; positioning an elastomeric body within the countersink; positioning the threaded connector through the elastomeric body and the hole of the permanent magnet; coupling the threaded connector to the rotor body. [0007] The present disclosure also provides for a rotor for a permanent magnet electric motor. The rotor may include a rotor body, the rotor body being generally cylindrical in shape and having an outer surface. The rotor body may include a mounting hole positioned to couple to a threaded connector. The rotor may also include a permanent magnet. The permanent magnet may be generally in the form of an annular section. The concave surface of the permanent magnet may have a diameter generally equal to the outer diameter of the rotor body. The permanent magnet may have a hole formed therein positioned to receive the threaded connector. The hole may have a countersink formed therein at the convex surface of the permanent magnet. The rotor may also include an elastomeric body positioned within the countersink between the threaded connector and the permanent magnet. [0008] The present disclosure also provides for a method. The method may include providing a rotor body. The rotor body may be generally cylindrical in shape. The rotor body may have an outer surface. The outer surface of the rotor body may have at least one dovetail channel. The method may also include providing a permanent magnet. The permanent magnet may be generally in the form of an annular section. The concave surface of the permanent magnet may have a diameter generally equal to the outer diameter of the rotor body. The permanent magnet may include at least one dovetail adapted to fit into the dovetail channel. The method may further include sliding the permanent magnet on the outer surface of the rotor body so that the dovetail couples to the dovetail channel. [0009] The present disclosure also provides for a method. The method may include providing a rotor body. The rotor body may be generally cylindrical in shape. The rotor body may have an outer surface. The method may further include providing a retaining ring. The method may further include providing a permanent magnet. The permanent magnet may generally be in the form of an annular section. The concave surface of the permanent magnet may have a diameter generally equal to the outer diameter of the rotor body. The permanent magnet may have at least one flange extending from an end of the permanent magnet. The flange may be adapted to allow the retaining ring to hold the permanent magnet to the rotor body by compressing the flange to the rotor body. The method may further include positioning the permanent magnet on the outer surface of the rotor body. The method may further include positioning the retaining ring about the rotor body and permanent magnet such that the retaining ring is generally aligned with the flange. BRIEF DESCRIPTION OF THE DRAWINGS [0010] The present disclosure is best understood from the following detailed description when read with the accompanying figures. It is emphasized that, in accordance with the standard practice in the industry, various features are not drawn to scale. In fact, the dimensions of the various features may be arbitrarily increased or reduced for clarity of discussion. [0011] FIG. 1 depicts a rotor having permanent magnets affixed thereto consistent with embodiments of the present disclosure. [0012] FIG. 2 depicts a partial cross section of the rotor of FIG. 1 . [0013] FIG. 3 depicts a partial cross section of a rotor having permanent magnets affixed thereto consistent with embodiments of the present disclosure. [0014] FIGS. 4 a , 4 b depict a rotor having permanent magnets affixed thereto consistent with embodiments of the present disclosure. DETAILED DESCRIPTION [0015] It is to be understood that the following disclosure provides many different embodiments, or examples, for implementing different features of various embodiments. Specific examples of components and arrangements are described below to simplify the present disclosure. These are, of course, merely examples and are not intended to be limiting. In addition, the present disclosure may repeat reference numerals and/or letters in the various examples. This repetition is for the purpose of simplicity and clarity and does not in itself dictate a relationship between the various embodiments and/or configurations discussed. [0016] As depicted in FIG. 1 , rotor 101 for use in a permanent magnet motor may include rotor body 103 . Rotor body 103 may be generally cylindrical in shape. In some embodiments, rotor body 103 may be coupled to output shaft 105 . As rotor 101 is rotated within the permanent magnet motor, output shaft 105 serves to transfer the rotational power generated by rotor 101 to other equipment (not shown). [0017] Rotor 101 may, in some embodiments, include one or more permanent magnets 107 positioned about the exterior surface of rotor body 103 . In some embodiments, as depicted in FIG. 1 , permanent magnets 107 may be annular in shape. The concave surface of each permanent magnet 107 may have generally the same diameter as the exterior surface of rotor body 103 . Permanent magnets 107 may be configured such that the magnetic axis of each permanent magnet is substantially aligned to be normal to the surface of rotor body 103 . In some embodiments, the magnetic field of adjacent permanent magnets 107 are in opposition, so that the magnetic pole of permanent magnets 107 alternate between North and South. In some embodiments, permanent magnets 107 may be formed by sintering of permanent magnet material such as, for example and without limitation, a rare-earth magnet such as neodymium. In other embodiments, permanent magnets 107 may be formed by a rapid solidification process as understood in the art. [0018] As depicted in FIG. 2 , permanent magnet 107 may be coupled to rotor body 103 . In some embodiments, permanent magnet 107 may have one or more holes 109 formed therein. Hole 109 is aligned so that when permanent magnet 107 is placed on the outer surface of rotor body 103 , hole 109 extends in a direction normal to the surface of rotor body 103 . In some embodiments, hole 109 may include countersink 111 . Rotor body 103 may include one or more mounting holes 113 positioned to align with holes 109 of permanent magnets 107 . In some embodiments, mounting holes 113 may be tapped to accept the thread of threaded fastener 115 . In some embodiments, threaded fastener 115 may be, for example and without limitation, a screw, bolt, or other threaded fastener. Countersink 111 may allow threaded fastener 115 to, when installed, remain below the outer surface of permanent magnet 107 which may, for example, avoid interference between threaded fastener 115 and other parts of the permanent magnet motor. [0019] In some embodiments, a thread-locking compound may be applied to threaded fastener 115 to, for example, prevent threaded fastener 115 from unintentionally unthreading from rotor body 103 . In some embodiments, a potting material or adhesive may be applied between, for example, rotor body 103 and permanent magnet 107 . [0020] In the embodiment depicted in FIG. 2 , threaded fastener 115 is a flathead screw with a matching tapered profile to that of countersink 111 . One having ordinary skill in the art with the benefit of this disclosure will understand that threaded fastener 115 may be replaced by a threaded connector having a different profile without deviating from the scope of this disclosure. Likewise, countersink 111 may have a different profile such as, for example and without limitation, a counterbore without deviating from the scope of this disclosure. For the purposes of this disclosure, the term “countersink” is intended to include both countersinks and counterbores unless specifically differentiated. [0021] In some embodiments, elastomeric body 117 may be positioned between the head of threaded fastener 115 and permanent magnet 107 when permanent magnet 107 is installed to rotor body 103 . Elastomeric body 117 may be formed of an elastomeric material, allowing elastomeric body 117 to be installed under elastic compression between threaded fastener 115 and permanent magnet 107 . Because threaded fastener 115 may have a thermal expansion coefficient and/or thermal conductivity different from that of permanent magnet 107 , threaded fastener 115 may thermally expand and increase in length more rapidly than permanent magnet 107 as permanent magnet 107 , threaded fastener 115 , and rotor body 103 increase in temperature during normal use. In such a case, the compressive stress on elastomeric body 117 between threaded fastener 115 and permanent magnet 107 may decrease. Elastomeric body 117 , being elastically deformed, increases in size as the stress thereon decreases, which may maintain the compressive force between threaded fastener 115 and permanent magnet 107 . Elastomeric body 117 may thus, for example, prevent any loosening of the attachment between permanent magnet 107 and rotor body 103 . [0022] Although depicted as a single O-ring, elastomeric body 117 may, in some embodiments, be, for example and without limitation, a single O-ring, multiple O-rings, an elastomeric washer, or a combination thereof. [0023] Likewise, as threaded fastener 115 and permanent magnet 107 decrease in temperature during normal operation of the permanent magnet motor, for example when the permanent magnet motor is shut off, threaded fastener 115 may thermally contract more rapidly than permanent magnet 107 . In this case, the compressive stress on elastomeric body 117 between threaded fastener 115 and permanent magnet 107 may increase. Elastomeric body 117 may elastically deform to, for example, prevent excess force from being exerted on permanent magnet 107 by threaded fastener 115 . Elastomeric body 117 may thus, for example, prevent threaded fastener 115 from crushing permanent magnet 107 . [0024] In order to assemble rotor 101 , a rotor body 103 may be provided. One or more mounting holes 113 may be formed in the exterior surface of rotor body 103 . In some embodiments, mounting holes 113 may be tapped to receive a threaded fastener. One or more permanent magnets 107 , having at least one hole 109 formed therein, each hole 109 positioned to align with a corresponding mounting hole 113 , each hole 109 having countersink 111 , is then positioned onto the outer surface of rotor body 103 . Elastomeric body 117 is then placed within countersink 111 . A threaded fastener, such as threaded fastener 115 , is then threaded into hole 109 and mounting hole 113 , such that the head of threaded fastener 115 mechanically couples permanent magnet 107 to rotor body 103 . [0025] Although FIG. 1 depicts a permanent magnet 107 being coupled to rotor body 103 by only one threaded fastener 115 , one having ordinary skill in the art with the benefit of this disclosure will understand that multiple screws 115 may be utilized for each permanent magnet 107 . Additionally, although depicted as being used for an internal rotor permanent magnet motor, one having ordinary skill in the art with the benefit of this disclosure will understand that permanent magnets 107 may be installed to the interior surface of a tubular rotor of an external rotor permanent magnet motor without deviating from the scope of this disclosure. Likewise, although described with permanent magnets 107 coupled to the rotor of a permanent magnet motor, permanent magnets 107 may be coupled to the stator of a permanent magnet motor in which the coils are positioned on the rotor without deviating from the scope of this disclosure. [0026] In some embodiments, rotor 201 may include rotor body 203 as depicted in FIG. 3 . Rotor body 203 may include one or more dovetail channels 205 adapted to interface with permanent magnets 207 . In such embodiments, permanent magnets 207 may include magnet dovetail 209 adapted to fit into dovetails 205 and thus retain permanent magnet 207 to rotor body 203 . In such an embodiment, permanent magnet 207 may be slid into dovetail channels 205 during assembly. In some embodiments, dovetail channels 205 may be formed by removing material from rotor body 203 . In some embodiments, dovetail channels 205 may be formed as a separate piece from rotor body 203 and affixed thereto by, for example and without limitation, threaded couplers. In some embodiments, dovetail channels 205 may be coupled to rotor body 203 by threaded couplers as described above. [0027] In some embodiments, rotor 301 may include rotor body 303 as depicted in FIGS. 4 a , 4 b . Permanent magnets 305 may include one or more flanges 307 as depicted in FIG. 4 a . Flanges 307 may, for example and without limitation, be adapted to receive retaining ring 309 when installed as depicted in FIG. 4 b . Retaining ring 309 may be adapted to encircle rotor body 303 and flanges 307 of permanent magnets 305 in order to retain permanent magnets 305 to rotor body 303 . In some embodiments, retaining ring 309 may be a split ring, the ends of which being coupled to one or more of rotor body 303 or the other end of retaining ring 309 . [0028] The foregoing outlines features of several embodiments so that a person of ordinary skill in the art may better understand the aspects of the present disclosure. Such features may be replaced by any one of numerous equivalent alternatives, only some of which are disclosed herein. One of ordinary skill in the art should appreciate that they may readily use the present disclosure as a basis for designing or modifying other processes and structures for carrying out the same purposes and/or achieving the same advantages of the embodiments introduced herein. One of ordinary skill in the art should also realize that such equivalent constructions do not depart from the spirit and scope of the present disclosure and that they may make various changes, substitutions, and alterations herein without departing from the spirit and scope of the present disclosure.

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BACKGROUND OF THE INVENTION This invention relates to personal electronic devices, such as wristwatches, pocket pagers, calculators, and organizers, having an EL lamp and a piezoelectric buzzer powered from a single inductor. An EL lamp is essentially a capacitor having a dielectric layer including a phosphor powder which glows in the presence of a strong electric field and a very low current. The dielectric layer is held between two electrodes, one of which is transparent. Because the EL lamp is a capacitor, an alternating current (AC) must be applied to cause the phosphor to glow, otherwise the capacitor charges to the applied voltage and the current through the EL lamp ceases. For personal electronic devices such as wristwatches, pocket pagers, and cellular telephones, an EL lamp is driven by an inverter which converts direct current from a small battery into alternating current. In order for an EL lamp to glow sufficiently, a peak to peak voltage in excess of about one hundred and twenty volts is necessary. The actual voltage depends on the construction of the lamp and, in particular, the field strength within the phosphor powder. While there are many ways to increase voltage, e.g. by using a transformer or a voltage doubler, most applications for an EL lamp use what is known as a “flyback” inverter in which the energy stored in an inductor is supplied to the EL lamp as a small pulse of current at high voltage. The inverter typically operates at high frequency (4 khz. or more) to minimize the size of the magnetics, i.e. the inductor or transformer, in the inverter. FIG. 1 is based upon the disclosure of U.S. Pat. No. 4,527,096 (Kindlmann). When transistor 14 turns on, current flows through inductor 15 , storing energy in the magnetic field generated by the inductor. When transistor 14 shuts off, the magnetic field collapses at a rate determined by the turn-off characteristics of transistor 14 . The voltage across inductor 15 is proportional to the rate at which the field collapses ( δi / δt ). Thus, a low voltage and large current is converted into a high voltage at a small current. The current pulses are coupled through diode 16 to the DC diagonal of a switching bridge having EL lamp 12 connected across the AC diagonal. Assuming that transistors 18 and 19 are conducting, the same amount of energy is supplied to lamp 12 each time transistor 14 turns off and, therefore, the voltage on the lamp is pumped up by a series of current pulses from inductor 15 as transistor 14 repeatedly turns on and off. Diode 16 prevents lamp 12 from discharging through transistor 14 . If transistor 14 were switched on and off continuously, the pulses would charge lamp 12 to the maximum voltage available from inductor 15 , e.g. about 140 volts. Since an EL lamp needs an alternating current or a variable direct current, the lamp would glow initially and then extinguish when the capacitance of the lamp became fully charged. To avoid this problem, the transistors in opposite sides of the bridge alternately conduct to reverse the connections to lamp 12 . The bridge transistors switch at a lower frequency than the frequency at which transistor 14 switches. The four bridge transistors are high voltage components, adding considerably to the size and cost of the circuit. In addition, the circuit is not single ended, i.e. one cannot ground one side of lamp 12 , which is preferred. One could use separate inverters for driving an EL lamp and a buzzer. In many applications, particularly watches, a second inverter is difficult to add, primarily because of the cost of a second inductor. It is known in the art to power a piezoelectric buzzer and an EL lamp from a single flyback inverter. FIG. 2 is based upon the disclosure of U.S. Pat. No. 4,529,322 (Ueda). In inverter 20 , transistor 14 is switched on and off at about 8 khz. to charge lamp 12 . When transistor 21 is conducting, lamp 12 is discharged. There is an average DC bias across lamp 12 , approximately equal to one half the maximum voltage, because the lamp is charged in only one direction and then discharged. DC bias on an EL lamp can cause corrosion and shorting of the electrodes of the lamp, particularly at elevated temperature and humidity, decreasing the life of the lamp. Another problem with inverter 20 is that transistors 21 and 22 draw current from terminal 13 through inductor 15 . This current is wasted since it does not contribute to powering lamp 12 , thereby reducing the efficiency of the inverter and decreasing battery life. A third problem with inverter 20 is that switch 25 is necessary for isolating piezoelectric buzzer 26 from the high voltage pulses applied to lamp 12 . High voltage pulses stress the piezoelectric element and can cause failure. In the Ueda patent, switch 25 is one of two ganged switches actuated by undisclosed means. FIG. 3 is based upon the disclosure of U.S. Pat. No. 5,313,117 (Kimball). Inverter 30 includes transistor 31 , inductor 32 , and transistor 33 connected in series between voltage source 34 and ground. Inductor 32 is alternately connected through transistors 35 and 37 to lamp 27 . Diode 36 is connected in a series with transistor 35 for preventing the transistor from operating in the inverse active mode, i.e. preventing transistor 35 from conducting current from the ground terminal through the forward bias based-collector junction when the voltage on lamp 27 is negative. Similarly, diode 38 prevents transistor 37 from operating in the inverse active mode when the voltage on lamp 27 is positive and greater than the battery voltage. The transistors, resistors, and diodes are implemented on a single chip. The inductor and capacitors are external devices coupled to the chip on a printed circuit board. External logic circuitry provides a series of pulse bursts alternately on output lines “X” and “Y”. These bursts are coupled to the bases of transistors 31 and 33 and cause the transistors to conduct alternately, thereby providing positive and negative half wave voltages to lamp 27 . Inverter 30 produces alternating current at a single ended output and one side of lamp 27 can be grounded. It remains a problem in the art to drive an EL lamp and a buzzer from a single inverter with as few components as possible with no waste current and with no DC bias. In view of the foregoing, it is therefore an object of the invention to provide a personal electronic device with an inverter having a single inductor for providing alternating current to an EL lamp and direct current pulses to a buzzer. Another object of the invention is to provide a personal electronic device with an inverter having no waste current. Another object of the invention is to provide a personal electronic device with an inverter having no DC bias. SUMMARY OF THE INVENTION The foregoing objects are achieved in this invention in which a personal electronic device includes an inverter having an output coupled to the junction of an EL lamp and a buzzer. The lamp and the buzzer are coupled in parallel with each other to ground or are coupled in series between a DC supply and ground. BRIEF DESCRIPTION OF THE DRAWINGS A more complete understanding of the invention can be obtained by considering the following detailed description in conjunction with the accompanying drawings, in which: FIG. 1 is a schematic of an inverter of the prior art; FIG. 2 is a schematic of an inverter of the prior art for powering an EL lamp and a piezoelectric buzzer; FIG. 3 is a schematic of an inverter of the prior art having a single ended output; FIG. 4 is a schematic of an inverter constructed in accordance with the invention; FIG. 5 is a schematic of an inverter constructed in accordance with an alternative embodiment the invention; FIG. 6 is a schematic of an inverter constructed in accordance with a preferred embodiment of the invention; and FIG. 7 is a variation of the embodiment shown in FIG. 4 . DETAILED DESCRIPTION OF THE INVENTION FIG. 4 illustrates an inverter constructed in accordance with the invention in which an EL lamp and a buzzer are coupled in parallel between the output of an inverter and ground. SCR 41 isolates buzzer 42 from the pulses produced by inductor 43 and transistor 44 . The pulses are coupled by diode 46 to bridge 47 where they are converted into alternating current through lamp 48 . Transistor 51 operates in synchronism with transistor 44 to discharge any charge accumulated on buzzer 42 . Buzzer 42 sounds when a high voltage is applied to signal input 53 . Because of the alternating current through lamp 48 , no separate discharge circuitry is needed and there is no waste current. Transistor 51 does not produce waste current because the transistor operates in synchronism with transistor 44 . FIG. 5 illustrates an inverter constructed in accordance with another aspect of the invention in which the EL lamp and the buzzer are coupled in series across the low voltage supply. In this embodiment, transistor 56 isolates buzzer 54 from the pulses produced by inductor 43 and transistor 44 . The pulses are coupled by diode 46 to the junction of bridge 47 and buzzer 54 . When transistor 56 is non-conducting, the pulses are applied to EL lamp 48 by bridge 47 to produce an alternating current through the lamp. For many applications, lamp 48 has a capacitance of about 3 nf and buzzer 54 has a capacitance of 10-15 nf. When transistor 56 is conducting, the pulses are coupled substantially through buzzer 54 , which has a much lower impedance than lamp 48 . Thus, only the buzzer appears to operate. Because of the impedance difference, only transistor 56 is needed to select between operating the lamp and operating the buzzer, simplifying the circuit. The operation of transistor 56 need not be synchronized with the operation of transistor 44 , further simplifying the circuitry. In FIG. 6, the EL lamp and the buzzer are coupled in series between supply and ground. Junction 61 is coupled to output 63 of an inverter constructed as illustrated in FIG. 3 . Lamp 64 is lit as long as the inverter is operating and as long as transistor 65 is not conducting. Applying a signal to input 66 causes transistor 65 to conduct and substantially all the current from the inverter goes through buzzer 69 , sounding the buzzer and extinguishing lamp 64 . In FIG. 7, EL lamp 71 is connected to the AC diagonal of bridge 72 and the DC diagonal of the bridge is coupled to junction 74 by diode 75 and to ground. Buzzer 76 is coupled to junction 74 by SCR 77 and is discharged by transistor 78 , which is connected in parallel with the buzzer. The base of transistor 78 is coupled to the base of transistor 79 and the two transistors switch together, thereby avoiding waste current when discharging buzzer 76 . Buzzer 76 is sounded by turning on SCR 77 , causing pulses from inductor to be coupled to the buzzer. Bridge 72 is off, preventing lamp 71 from being charged or discharged. The invention thus provides an inverter for powering an EL lamp or a buzzer by providing AC for the lamp and pulsed DC for the buzzer. Waste current is eliminated by eliminating transistors coupled in parallel with the switch transistor in series with the inductor. Having thus described the invention, it will be apparent to those of skill in the art that various modifications can be made within the scope of the invention. For example, one can interchange power and ground or substitute PNP transistors for NPN transistors, and vice-versa.

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RELATED APPLICATIONS [0001] This application is the national stage, under 35 USC 371, of international application PCT/EP2014/057212, filed on Apr. 9, 2014, which claims the benefit of the May 27, 2013 priority date of German application DE 102013105428.5, the content of which is herein incorporated by reference. FIELD OF INVENTION [0002] The invention relates to packaging, and in particular, to producing multipacks of containers. BACKGROUND [0003] A multipack is a group of containers that have been packaged together. A common way to form a multipack is by forming a container group and shrink-wrapping it. This results in additional method steps. In addition, it requires consuming a special film and expending considerable energy. To make matters worse, sometimes the film obscures the view of important features such as labels or imprints on the containers. As a result, the visual appearance of such multipacks leaves much to be desired. [0004] A known way to overcome these disadvantages is by gluing the containers together with adhesive. A variety of adhesives can be used. These include hot-melt adhesives. Such adhesives can be melted on by applying heat. After cooling, the adhesive binds the containers. [0005] The removal of individual containers from the multipack is not always problem-free however. Ideally, the individual containers are tightly bonded to one another. This implies a need for a high adhesive strength. But high adhesive strength makes it difficult to remove individual bottles from the multipack. In addition to this, a wide temperature application range is required for the adhesive used. Additionally, it is desirable to be able to peel the adhesive off the surface of the container. SUMMARY [0006] An object of the invention is that of producing multipacks of containers in a simple and economical way while still providing a mechanically stable multipack. [0007] To achieve this, the method described herein uses at least two different adhesivities for production of multipacks. This can be done by using two or more different adhesives or bonding agents. [0008] A multipack can be formed of only two containers joined by an adhesive spot. In one aspect, the adhesive spot has zones of different adhesivity. This is typically implemented by making the zones out of different adhesives. The overall adhesive strength of the adhesive spot is thus the integral of a spatially varying adhesivity over the extent of the adhesive spot. [0009] Most multipacks have 2n containers, where n>1. In these embodiments, there are at least three adhesive spots. In some embodiments, individual adhesive spots have two or more zones of different adhesivity, typically implemented by using different adhesive materials. Alternatively, different adhesive spots can be made to differ in ways that affect their adhesivity. This might include having different thicknesses, spatial extents, and expansions, or having adhesive spots that undergo different preliminary treatments, or any combinations thereof. [0010] In some embodiments, adhesive spots in an inner region of the multipack exhibit a greater expansion than at those at its periphery. As a result, the containers located in the interior of the multipacks are connected to each other more securely than containers at the periphery of the multipack. As a result, containers at the periphery of the multipack can be released more easily than those in the interior. [0011] Some embodiments rely on the fact that an adhesive spot that that has expanded substantially often has increased adhesive strength. As used herein, adhesive strength is the integral of adhesivity as measured in units of force per unit area, such as N/mm 2 . The total adhesive strength is thus the integral of adhesivity over the area of the adhesive spot. This means that the one can control the adhesive strength of an adhesive spot by controlling its area. [0012] In some embodiments, the adhesive spots have different thicknesses. This feature is useful because most multipacks are formed by assembling essentially cylindrical containers. Thus, different thicknesses are required to achieve contact between different surfaces. Additionally, the greater the layer thickness as applied, the more the spot will spread when the containers are brought into contact. Since adhesive strength depends on surface area of the spot, different spots will again have different adhesive strengths depending on the thickness of the applied adhesive. [0013] In addition to this, the adhesive spots can have different compositions. For example, an adhesive spot can have one adhesive or more than one adhesive. This makes it possible to control the overall adhesive strength of the adhesive spot and to also have adhesive spots of different adhesive strengths at different places in the multipack. [0014] Other ways to control adhesive strength on a spot-by-spot basis include applying different pre-treatments to the different adhesive spots. For example, in some spots, the adhesive is applied over a base layer or coating such that the adhesive and base layer cooperate to attain an adhesivity that differs from that of an adhesive by itself. [0015] Alternatively, pre-treatment can be carried out to control adhesivity. One way to do this is to cross-link the adhesive, for example by exposing it to ultraviolet radiation. This will polymerize the adhesive and result in increased cohesion and/or adhesive strength. [0016] In some embodiments, the adhesive spots are designed and placed such that containers near the center of the multipack or within its interior are joined with relatively high adhesive strengths, and containers near the periphery are joined with lower adhesive strengths. This results in containers at the periphery being easier to remove from the multipack than those in the interior. [0017] In another aspect of the invention, the differently formed adhesives have different chemical and/or physical properties. [0018] As noted above, it is useful to have variable adhesive strengths and/or the peel strengths. To ensure that adhesion between containers is adequate, it is useful to adhesivities in the range from approximately 0.1 N/mm 2 to 1 N/mm 2 . [0019] The “peel strength” relates to the ability of the adhesive to be able to adhere to the container. Peel strength is measured by applying a constant force to remove the adhesive and seeing how long it takes to do so. A short time indicates a low peel strength, and vice-versa. [0020] In most cases, the arrangement of adhesive spots is such that adhesive spots within the interior of the multipack tend to have greater adhesive strength and peel strength than those at the periphery of the pack. This promotes mechanical support of the inner cohesion of the multipack while concurrently permitting easy detachment of the containers at the periphery. [0021] An adhesive spot can be made out of two different adhesives. In most cases, the two different adhesives will occupy different zones of the adhesive spot. In this situation, the zones may in principle delimit one another so that they are contiguous with each other. [0022] As an alternative, or in addition, it is also possible for the zones to be spaced apart from one another, and also to be arranged relative to each other according to some preselected configuration. The zones thus take a form similar to the dots on a playing die. The dots that mark the individual zones in such cases can be formed by the different adhesives. [0023] In some embodiments, the adhesive spot has a center zone made of an adhesive with high adhesivity. Then, zones around this center zone are made of adhesive with lower adhesivity. These zones are distributed around the center zone in a circular or star-shaped fashion. In this way, the adhesives can be combined in any desired manner in order to define a particular adhesive spot. [0024] It is also advantageous in some cases for adhesive spots at different vertical locations on a container to have different adhesivities. For example, in some embodiments the adhesive spots on the bellies of the containers have higher adhesive strength than those on the base. This makes it easier for consumers to detach the container at the base and then to use the container as a lever to help detach the stronger adhesive at the belly. [0025] In most cases work is carried out with spots of bonding or adhesive agents which in each case are realized in pairs; i.e. they are located both on the belly as well as on the base of the container concerned. [0026] In another variant, adhesive spots inside the multipack are applied in different circumferential positions on the container. This affects the ease with which a container can be peeled off the multipack. A similar result can be achieved by providing adhesive spots along the container axis and varying the adhesive strength of those adhesive spots. [0027] Adhesive parameters other than adhesive strength and/or peel strength can also be varied. For example, one can use heat-resistant adhesive or cold-resistant adhesive. The heat-resistant adhesive is typically well-suited for applications in the temperature range from some 10° C. to 45° C., whereas cold-resistant adhesive is typically well-suited for a temperature range of, for example, −6° C. to 20° C. In this way, the production of the multipack can be carried out in its entirety and worldwide in the same manner and with recourse to concordant adhesives. Essentially, depending on the outside temperature or ambient temperature respectively, either the heat-resistant adhesive or the cold-resistant adhesive develops its desired effect. [0028] A suitable type of adhesive is a plastic melt adhesives. Such melt adhesives melt when heated and then develop cohesion and inner strength upon cooling. Examples of melt adhesives are those that consist basically of one or more polymers, supplemented by additives. Suitable base polymers include ethylene-vinyl-acetate (EVA), polyolefins (APAO), polyamides (PA), rubber adhesives (SIS/SBS) and others. In addition to this, additives such as waxes or resins, such as tackifiers, can be added. Such waxes serve as diluting agents and reduce the viscosity and adhesion. Tackifiers reduce the cohesion and at the same time increase the tackiness, and in consequence the attainable adhesive strength. [0029] The inventive method thus provides a way to produce multipacks that satisfies requirements that are inherently in conflict. In this way, the multipack is in the first instance produced as filmless, and it is therefore possible in practice, as heretofore, to develop the steps of film application, film shrinkage, and also the provision of the film. In addition to this, the multipacks do not have a film. Therefore, it is easier for the consumer to see the labels. [0030] Additionally, with the containers connected with adhesive spots as described herein, the mechanical stability of the multipack becomes comparable to that of a multipack that has been wrapped with film. As a result, there is no need to make accommodations when handling and transporting such a multipack. Additionally, it is possible to remove containers from the multipack with ease. [0031] In some embodiments, the adhesive strength of adhesive spots varies with location on a single container. For example, it is possible to have a highly adhesive spot at the container's belly and a less adhesive spot at the container's base. In that case it will be easier to detach the container from the top. Or, the configuration can be reversed to that the more adhesive spot is at the base and the less adhesive spot is at the belly. [0032] The invention opens up the possibility of adapting the adhesive and the adhesive spot so that one has different adhesive strengths at different locations within the multipack. This flexibility makes it possible to more easily tune the mechanical requirements to accommodate multipacks of different sizes and shapes while taking into account sizes and weights of sizes and weights of the containers. [0033] In this connection, the individual containers are, for example, initially not yet fully formed in the channels, and are formed into temporary container groups. Additionally, the separation of the containers in each channel takes place in such a way that, in the transport direction, the containers in each channel exhibit a predetermined spacing interval from one another. The respective containers are next aligned by controlled rotation about the container axis. To do this, the respective container in each case is provided with an alignment feature, in order then to be able to produce the spot of applied bonding or adhesive agent after the separation in the channel. Finally, the aligned containers are connected to one another to form in each case compacted and shaped container groups, in that, for example, a container provided with the relevant spot of applied bonding or adhesive agent is connected to a container without such a spot. The essential advantages are to be seen herein. [0034] In one aspect, the invention features a method of producing multipacks of containers by using different adhesivities to interconnect containers. This can include selecting first and second plastic melt adhesives that melt as a result of exposure to heat and that develop cohesion after cooling. Adhesive spots are then placed on surfaces of containers. The adhesive spots have at least two different adhesivities. The containers are then connected to each other using the adhesive spots, thereby forming the multipack. [0035] Practices of the invention include those in which the adhesives have different physical properties and those in which they have different chemical properties. [0036] Practices of the invention also include those in which adhesive spots differ by having different thicknesses, those in which they differ by having different compositions, those in which they differ by having different spatial extents, and those in which they differ by having undergone different pre-treatment procedures. [0037] In some practices, each adhesive spot is made of two different adhesives. Among these practices are those in which the adhesives define different zones of the adhesive spot. These zones can adjoin one another. Alternatively, they can define a zonal archipelago in which the zones are separated from each other. Among these are adhesive spots in which the zones form a pre-selected configuration. [0038] In other practices, there are two kinds of adhesive spots, one made with a first adhesive and the other made with a second adhesive. [0039] Other practices include placing die spots of adhesive in different vertical and/or horizontal positions on a container, placing die spots of adhesive in different circumferential positions on a container, placing die spots of adhesive in different radial positions on a container, and placing die spots of adhesive in different axial positions on a container. [0040] Some practices include the use of adhesives having different adhesivities, and/or adhesives that have undergone differing preliminary treatments. [0041] In yet other practices, the multipack is a filmless multipack. [0042] Also among the practices are those in which the containers are arranged according to rows and columns in the multipack. In these practices, placing adhesive spots on surfaces of containers includes placing them in a manner that causes an adhesive strength that connects rows to each other to be different from an adhesive strength that connects columns to each other. [0043] Some practices include placing adhesive spots in a manner such that the adhesive strength between containers varies as a function of location of said containers within said multipack. Among these are those practices in which a first container is at a periphery of said multipack, a second container is at an interior of said multipack, and adhesive spots are so placed as to cause the first container to bond to an adjacent container with a first adhesive strength, and to cause the second container to bond to a neighboring container with a second adhesive strength that is greater than the first adhesive strength. BRIEF DESCRIPTION OF THE DRAWINGS [0044] These and other features and advantages of the invention will be apparent from inspection of the following detailed description and the accompanying figures, in which: [0045] FIG. 1 shows a multipack of containers produced in accordance with the method according to the invention, [0046] FIG. 2 shows the multipack according to FIG. 1 , with a container detached and a close-up view of a multi-zonal adhesive spot, and [0047] FIGS. 3A and 3B show two principle methods for the application of the spot of applied bonding or adhesive agent during the realization of an alternative multipack. DETAILED DESCRIPTION [0048] FIGS. 1 and 2 show a multipack 1 having containers 2 joined to each other by adhesive spots 3 . The resulting multipack 1 avoids the use of shrink wrap or film. [0049] The particular multipack 1 shown in FIG. 1 is a six-piece multipack because it has six containers 2 . However, other numbers of containers 2 can be formed into a multipack 1 . [0050] In some multipacks 1 , the individual containers 2 are PET bottles. However, other types of containers can be used. [0051] The adhesive spots 3 are spots of bonding or adhesive agents that connect the individual containers 2 to one another. As used herein, “adhesive” refers to any bonding or adhesive agent.” An adhesive spot 3 is made of one or more of these bonding or adhesive agents. [0052] For the customer's convenience, a multipack 1 has an optional carrying handle or carrying loop 4 having first and second ends that connect to opposed first and second containers 2 as shown in FIGS. 1 and 2 . In some embodiments, the carrying loop 4 is adhesively bonded to the containers 2 . [0053] Each container 2 also has an alignment feature 5 . These alignment features 5 are used by a container-processing machine as a basis for rotating individual containers 2 about their container axes so as to bring the adhesive spot 3 into the desired position. [0054] In FIG. 2 , one container 2 has been removed from the multipack 1 to reveal the locations of the adhesive spots 3 . It can be seen that adhesive spots are placed so that every container has one or more adhesive spots 3 that face its adjacent containers. The adhesive spots 3 can be found on the belly, on the head, or near the base of a container 2 . It is of particular importance that each point of contact between two containers 2 in a multipack 1 have an adhesive spot thereon, as shown in FIGS. 3A and 3B . [0055] FIGS. 1 and 2 show a paired arrangement in which a container 2 has a pair of adhesive spots 3 at its head or, respectively, at its belly and near its base. In some cases, an adjacent container 2 does not have any adhesive spot 3 at all. In other cases, the two adhesive spots are on different containers 2 . For example one container 2 has the adhesive spot 3 on the head side and an adjacent container 2 has an adhesive spot 3 on its base. [0056] In some embodiments, it is useful for the adhesive spot 3 to made from least two adhesives. The enlarged portion of FIG. 2 shows an adhesive spot 3 formed by first and second adhesives that define first and second zones 3 ′, 3 ″ of the adhesive spot 3 . The different adhesives have different physical or chemical properties. [0057] In the embodiment show, the first and second zones 3 ′, 3 ″ of the adhesive spot 3 are spaced apart to form an archipelago of zones 3 ′, 3 ″ arranged in a preselected configuration. However, in other embodiments, the zones 3 ′ 3 ″ are contiguous, and thus do not form adhesive islands within the spot 3 . [0058] In the illustrated embodiment, the zones 3 ′, 3 ″ are arranged like the spots in a standard five-spot die from a pair of dice used in a typical casino for such games as craps. The arrangement features a centered first zone 3 ′ and four second zones 3 ″ that define vertices of a square centered about the first zone 3 ′. [0059] In the configuration shown, the first zone 3 ′ is made of a first adhesive having a high adhesive strength. In contrast, the second zones 3 ″ are made of a second adhesive having an adhesive strength that is lower than that of the first adhesive. This arrangement enables a container 2 to be easily detached from the multipack 1 , as illustrated in FIG. 2 . [0060] In the embodiments of FIGS. 1 and 2 , the adhesive spots 3 and any zones 3 ′, 3 ″ thereof are arranged in horizontal planes that are coplanar. In this situation there is the further possibility of applying the individual adhesive spots 3 , 3 ′, 3 ″ inside the multipack 1 in different positions on the container 2 , as indicated in FIGS. 3A and 3B . These can be placed in the same horizontal plane, in different vertical positions, or in different positions in relation to a longitudinal axis of the container 2 . [0061] Each container 2 has a container axis that defines a cylindrical coordinate system for that container 2 . Adhesive spots 3 can be applied anywhere on the surface of that container 2 at any axial coordinate and at any circumferential coordinate defined by the cylindrical coordinate system. [0062] FIGS. 3A and 3B show containers 2 arranged in rows and columns in a multipack 1 . Although only four containers are shown, it will be understood that a multipack is in effect a container lattice for which the arrangement shown in FIGS. 3A and 3B forms a primitive cell that is tiled to form the lattice. Thus, the description of FIGS. 3A and 3B is applicable to any subset of four containers in a larger multipack 1 . [0063] The multipack 1 consists of a first container, a second container, a third container, and a fourth container arranged to form vertices of a square. The first and second containers define a top row, the third and fourth containers define a bottom row, the first and third container define a left column, and the second and fourth containers define a right column. A first set of adhesive spots 3 ′ joins the left and right columns of containers 2 and a second set of adhesive spots 3 ″ joins the top and bottom rows of containers 2 . [0064] A convenient way to refer to the different circumferential coordinates of the adhesive spots 3 ′, 3 ″ in FIGS. 3A and 3B is by reference to different positions on a clock face. [0065] In FIG. 3A , each container in the left column has an adhesive spot 3 ′ at the three o'clock position, whereas each container in the right column has an adhesive spot 3 ′ at the nine o'clock position. These spots 3 ′ hold the two columns together. [0066] Additional spots 3 ″ hold the top row to the bottom row. In particular, the second container, which is in the top row and right column, has an adhesive spot 3 ″ at the five o'clock position while the fourth container, which is in the bottom row and the right column, has an adhesive spot 3 ″ at the one o'clock position. Meanwhile, the first container, which is in the top row and left column, has an adhesive spot 3 ″ at the seven o'clock position and the third container, which is in the bottom row and left column, has an adhesive spot 3 ″ in the eleven o'clock position. [0067] An alternative way to describe the circumferential coordinates of the adhesive spots 3 ′, 3 ″ is by identifying an inter-spot angle formed by a first line that extends from the first adhesive spot 3 ′ to the container axis, and a second line that extends from the second spot 3 ″ to the container axis. In the embodiment shown in FIG. 3A , these inter-spot angles are all obtuse angles. In contrast, in the embodiment shown in FIG. 3B , the second adhesive spots 3 ″ have been interchanged so that the resulting inter-spot angle becomes acute. [0068] In some embodiments, the adhesive strength that connects columns to each other can differ from that connecting rows to each other. This affects the manner in which one would separate containers from the multipack 1 . For instance, if the adhesive strength connecting columns to each other is the greater of the two, it will be easier to separate one row at a time from the multipack 1 . Conversely, if the adhesive strength connecting rows to each other is the greater of the two, it will be easier to separate one column at a time from the multipack 1 . [0069] This difference between adhesive strengths is suggested in FIGS. 3A and 3B by showing adhesive spots 3 ′, 3 ″ that have different thicknesses, with the second adhesive spots 3 ″ being noticeably thicker than the first adhesive spots 3 ′. Having first and second sets of adhesive spots 3 ′, 3 ″ with different adhesive strengths can be executed in different ways, for example by using different adhesive materials or different configurations of adhesive materials within a spot, or by pre-treatment of the adhesive material.

4y

CROSS-REFERENCE TO RELATED APPLICATIONS [0001] This is a continuing application, under 35 U.S.C. §120, of copending international application No. PCT/EP2006/067121, filed Oct. 6, 2006, which designated the United States; this application also claims the priority, under 35 U.S.C. §119, of German patent application No. DE 10 2005 054 507.6, filed Nov. 16, 2005; the prior applications are herewith incorporated by reference in their entirety. BACKGROUND OF THE INVENTION Field of the Invention [0002] The invention relates to a method of producing a belt package for pneumatic vehicle tires comprising at least two belt plies. The invention also relates to certain device components to be used in the method, and to a vehicle tire produced by the method. [0003] Commonly assigned German published patent application DE 41 08 260 A1 and its corresponding European patent EP 0 503 532 B1 describe a method for producing tread/belt packages for pneumatic vehicle tires that allows a large number of tread/belt packages to be produced in as short a time as possible. In this case, at least two plies of a belt are placed on a first of two belt drums which are arranged on coaxial shafts and can be driven independently of each other, the plies being drawn off from a belt ply feeder. The entire belt ply package is transferred by means of a transfer device to the second belt drum, on which a winding bandage is created by coiling and a tread is placed on. In the meantime, the belt plies for a further belt package are applied essentially simultaneously on the first belt drum. The finished tread/belt package is removed by means of a transfer device of the second belt drum. [0004] Commonly assigned German published patent application DE 40 21 672 A proposes, for the purposed of automating tire production, to wind up the individual plies of a belt on a first belt drum, a second belt drum being provided, and the second and first belt drums being configured in such a way that one can be brought axially inside the other. This allows the segments of the second belt drum to take up the package of plies, the two belt drums subsequently being removed from each other and it being possible for a further package of plies to be produced on the first belt drum. On the second belt drum, the first package of plies is then also provided if necessary with a winding bandage and subsequently completed with the tread to form a complete tread/belt package. [0005] In the successive placement of the individual plies of multiply belts, it is repeatedly found that the supporting surface of an applied belt ply is no longer cylindrical but distinctly contoured or uneven. This may be attributable to the fact that the materials placed one on top of the other for the belt plies have different thicknesses and widths or that further components, such as for instance cover strips or belt edge pads, are occasionally applied at the edges of the belt. With each web of material that is placed on and each component that is placed on, the supporting surface becomes more irregular. The contoured supporting surface produced in this way does not allow the subsequent web of material to be automatically placed on and automatically spliced with the devices that are currently available. SUMMARY OF THE INVENTION [0006] It is accordingly an object of the invention to provide a method of producing a belt package for a vehicle tire which overcomes the above-mentioned disadvantages of the heretofore-known devices and methods of this general type and which provides for a method by which the automatic placement and the automatic splicing of all the belt plies of a belt package is possible, even if additional components, such as belt edge pads, are to be applied and a contoured outer contour of the already applied belt ply or plies is obtained during the buildup of the belt. [0007] With the foregoing and other objects in view there is provided, in accordance with the invention, a method of producing a belt package for a pneumatic vehicle tire with at least two belt plies, the method which comprises: [0008] automatically placing belt plies on a belt drum and automatically splicing the belt plies to build up at least two sub-packages of belt plies independently of one another; and [0009] joining the sub-packages of belt plies together to form a complete belt package. [0010] In other words, the objects of the invention are achieved in that the belt plies are built up in at least two sub-packages, which are automatically placed on a belt drum and automatically spliced independently of one another, the sub-packages being joined together to form the complete belt package. [0011] The method according to the invention allows all the belt plies to be automatically placed and automatically spliced. The sub-packages are created in such a way that, in particular if ever a web of material were to become too uneven, to permit automatic placement and automatic splicing of the next-following belt ply, the remaining belt ply or the remaining belt plies is/are built up separately in at least one additional sub-package, the sub-packages subsequently being joined to one another. [0012] With the method according to the invention, complete belt packages can be built up and created in a very flexible way. For example, one belt ply may be created in each sub-package, or two or more belt plies may be contained in a sub-package. Usually, belt edge pads, edge strips or similar components are applied to at least one of the sub-packages as outermost components. Precisely these components would provide a very contoured, uneven supporting surface for the following belt ply. According to the invention, direct placement of the next-following belt ply is no longer necessary. [0013] The method according to the invention can, furthermore, be carried out in a very efficient way. In this connection, it is of advantage if at least one of the sub-packages is transferred from the belt drum to a belt carrying ring and remains positioned on this until it is joined together with another sub-package. In this case, the sub-package built up on a belt drum can be joined together with a sub-package held on a belt carrying ring. A further advantage of the method is that the required number of belt carrying rings and belt drums can be used. [0014] Before joining together two sub-packages, one of which is on a belt carrying ring and the second of which is on a belt drum, all that is necessary is to position the belt carrying ring over the belt drum. Joining together of the two sub-packages can be subsequently carried out in a very easy way. The alternatives available here comprise joining together by reducing the inside diameter of the belt carrying ring, joining together by increasing the outside diameter of the belt drum and a combination of these two measures at the same time. [0015] The invention also relates to a belt drum for use in the method according to the invention that is wherein its supporting surface is slightly concavely curved. On such a belt drum, the belt plies can be created in an already somewhat pre-contoured form. [0016] A belt drum configured in such a way is used with preference with a belt carrying ring on which the inner surface is slightly convexly curved. [0017] The invention also relates to a pneumatic vehicle tire produced by the method according to the invention. A tire produced in this way is of particularly high quality, since it can have a high degree of uniformity. [0018] Other features which are considered as characteristic for the invention are set forth in the appended claims. [0019] Although the invention is illustrated and described herein as embodied in method for producing a belt package for a pneumatic vehicle tire, it is nevertheless not intended to be limited to the details shown, since various modifications and structural changes may be made therein without departing from the spirit of the invention and within the scope and range of equivalents of the claims. [0020] The construction and method of operation of the invention, however, together with additional objects and advantages thereof will be best understood from the following description of specific embodiments when read in connection with the accompanying drawings. BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS [0021] FIG. 1 is a diagrammatic view of a belt drum and a belt carrier ring illustrating a first step of the method according to the invention; [0022] FIGS. 2-5 illustrate various individual steps in the buildup of a four-ply belt of a pneumatic vehicle tire using the belt drum and the belt carrying ring; and [0023] FIG. 6 shows an alternative embodiment in which the belt carrier ring has a slightly convex inner surface and the belt drum has a slightly concave surface. DETAILED DESCRIPTION OF THE INVENTION [0024] Referring now to the figures of the drawing in detail, the apparatus used in the invention comprises a belt drum 1 with a cylindrical supporting surface and a belt carrying ring 2 with a cylindrical inner surface 2 a , the lateral surface of a cylinder respectively being meant. At least one of the two components, but preferably both, is or are segmented in the known way and expandable and retractable in the radial direction. The method according to the invention is described in more detail on the basis of the buildup of a belt package comprising four belt plies 3 , 4 , 5 , 6 and having two belt edge pads 7 between the second and third belt plies 4 , 5 . A belt package built up in such a way is used, for example, in the pneumatic vehicle tires for heavy trucks. The radially innermost belt ply 3 is referred to as the first belt ply, and the radially outermost belt ply 6 is referred to as the fourth belt ply. The belt plies 3 , 4 , 5 , 6 are produced in a known way from cut-to-length webs of steel cords embedded in a rubber compound. [0025] To build up the four-ply belt package, the third belt ply 5 and subsequently the fourth belt ply 6 are automatically placed onto the cylindrical belt drum 1 and automatically spliced. Referring, first, to FIG. 1 , there is shown the finished sub-package comprising the belt plies 5 and 6 on the belt drum 1 . The belt carrying ring 2 is then moved over the belt drum 1 and retracted in the radial direction to reduce its inside diameter. By means of clamping devices that are not represented, the belt carrying ring 2 takes over the sub-package comprising the third and fourth belt plies 5 , 6 . FIG. 2 shows the belt drum 1 and the belt carrying ring 2 just before the takeover of the sub-package at the two belt plies 5 , 6 . While the two belt plies 5 , 6 remain positioned on the belt carrying ring 2 , the first belt ply 3 and subsequently the second belt ply 4 are automatically placed on the cylindrical belt drum 1 and automatically spliced. Then, the two belt edge pads 7 , profiles made of a rubber compound, are placed on at the side edges of the belt ply 4 . FIG. 3 shows this stage of the buildup of the sub-package comprising the belt plies 3 , 4 and the pads 7 . Then, the belt carrying ring 2 is positioned over the belt drum 1 , as represented in FIG. 4 . By radial expansion of the segments of the belt drum 1 , the components on the belt drum 1 —the first and second belt plies 3 , 4 and the two belt edge pads 7 —are joined to the third and fourth belt plies 5 , 6 on the belt carrying ring 2 . Then, the clamping of the belt plies 5 , 6 is released and the belt carrying ring 2 is moved into a position to the side of the belt drum 1 , as FIG. 5 shows. The finished belt package is then on the belt drum 1 . The buildup of the green tire with a belt package produced in such a manner can be carried out in a known way. In particular, the finished belt package is provided with a tread, transferred to a transfer device and transferred by the latter to an already built up tire carcass and positioned on the tire carcass. [0026] In the case of belt packages built up by the method according to the invention, the need for a belt ply to be applied directly to a substructure having a contoured supporting surface is avoided. This would be the case for instance if the third belt ply 5 were applied directly to the second belt ply 4 , provided with the two belt edge pads 7 . In this case, it would no longer be possible to place the third and fourth belt plies on automatically and splice them automatically. [0027] In the case of the embodiment represented here, the sub-package comprising the first and second belt plies 3 , 4 and the two belt edge pads 7 is increased in diameter, in order to be joined to the second sub-package comprising the third and fourth belt plies 5 , 6 . As an alternative to this, it may also be envisaged to reduce the sub-package comprising the third and fourth belt plies 5 , 6 in diameter to establish the join with the belt sub-package comprising the first and second belt plies 3 , 4 and the two belt edge pads 7 . The reduction in diameter is effected by means of the belt carrying ring 2 . In the case of a further possible alternative, the two sub-packages may be joined together by increasing the diameter of the belt drum 1 and at the same time reducing the diameter of the belt carrying ring 2 . [0028] A number of belt carrying rings and a number of belt drums may be used. As a result, the buildup of the belt package can be performed in a largely flexible manner. For instance, in the case of a further configurational variant that is not separately shown, it is possible for the spliced third belt ply 5 to be transferred from the belt drum onto a belt carrying ring and the fourth belt ply 6 to be automatically placed on its own on the belt drum and spliced. Joining together of the two belt plies 5 , 6 can be performed in a way analogous to the method steps shown in FIGS. 3 to 5 . Equally, the sub-package may be created from the first and second belt plies with the two belt edge pads 7 subsequently placed on. It may in this case be envisaged to place belt edge strips on additionally in the case of one or more of the belt plies 3 , 4 , 5 and 6 . [0029] As described, the belt drum or the belt drums can provide a cylindrical supporting surface. As an alternative to this, it is possible to provide a supporting surface that is slightly concavely contoured in cross section on the belt drum or the belt drums. In an analogous way, the segments of the belt carrying ring or rings may also be contoured, here by means of a curvature that is slightly convex in cross section. The convex surface of the ring 2 and the concave peripheral surface of the drum 1 are illustrated in FIG. 6 .

4y

BACKGROUND OF THE INVENTION 1. Field of the Invention the present invention relates to a reasoning system by knowledge activation for automatic generation of rules to execute rapid reasoning for solving problems, and composing method thereof. 2. Description of the Prior Art A reasoning system by knowledge activation having a knowledge obtaining mechanism, a failure diagnosis system for mechanical systems (Jyoho Syori Gakkaishi 30.5 (1989)) and a knowledge base system (JP-A-63-271534 (1988)) having a function for generating new logically correct rules from conventional knowledge have been disclosed. The failure diagnosis system described above is a system for discovering failed members based on structure of apparatus and behavior of composing members, and the system generates knowledge relating to failure of the composing members by eliminating candidates in normal condition from a group of failed member candidates enumerated from data of reasoning process. And the knowledge based system described above prepares new knowledge by the conversion of conventional knowledge stored in a knowledge base in another logically equivalent expression form. The above described systems have an advantage to generate knowledge which is not ready previously and to enable the knowledge be utilized for solving problems. However, it is necessary for a reasoning system by knowledge activation to have a mechanism to generate selectively effective new knowledge for solving problems when a function to generate knowledge is provided to the reasoning system by knowledge activation. Reasoning system by knowledge activation without the function described above have following problems. a) The quantity of knowledge is increased because of generation of unnecessary knowledge. b) As the result, reasoning using the knowledge needs long time for collation of condition. c) Computer memories having large capacity are necessary for storage of a large quantity of knowledge. Thus, for a large scale reasoning by knowledge activation system, the effective knowledge to solve problems, or in other words, whether or not the generated knowledge is able to reach a solution with the least amount of steps is a crucial point. SUMMARY OF THE INVENTION (1) Objectives of the Invention The object of the present invention is to provide a reasoning system by knowledge activation having a function for restraining the above described increment of the knowledge quantity and obtaining reasoning rules to find solutions rapidly. (2) Methods Solving the Problems: To achieve the objective described above, in accordance with the present invention, a target region of reasoning is composed hierarchically. An approximate rule to execute reasoning rapidly is assigned to higher hierarchy while a rule to generate the approximate rule for the higher hierarchy by detailed reasoning is assigned to lower hierarchy. Then, in the process of reasoning, the approximate rule is executed when the premise part of the approximate rule is established, and the reasoning at the lower hierarchy is continued when the premise part of the approximate rule has not been established. The approximate rule is generated by combining the premise part and the concluding part of the generation rule, that rule describing the relationship between the premise part and the concluding part of the approximate rule, only when the result of the detailed reasoning satisfies the relationship between the premise part and the concluding part of the generation rule. In accordance with the method described above, only effective knowledge for solving the problems is selectively generated because new rules are generated only in the case where the result of the detailed reasoning satisfies the relationship between the premise part and the concluding part of the approximate rule. Further, as the generated knowledge executes approximate and fast reasoning at the higher hierarchy, the problems can be effectively resolved. In other words, in accordance with the present invention, the rule for solving problems rapidly can be obtained by restraining the increment of knowledge quantity. Moreover, in accordance with the present invention only knowledge which is effective for solving problems can be selectively prepared by the rule which describes preparing condition of the knowledge. And, in accordance with the reasoning system by knowledge activation of the present invention, the rules for solving problems rapidly are not necessary to prepare the rule previously employed by system engineers or users, because the rules can be generated automatically. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a system diagram illustrating an embodiment of the reasoning system by knowledge activation of the present invention; FIG. 2 is a block diagram showing an example of a plant system; FIG. 3 is a figure showing an example of the higher hierarchy frame expression; FIG. 4 is a figure showing an expressive example of the lower hierarchy frame; FIG. 5 is a figure showing an expressive example of the approximate rule; FIG. 6 a figure showing an expressive example of the detailed rule; FIG. 7 is a figure showing an expressive example of the generation rule of approximate rule; FIGS. 8, 9 (a) 9 (b) are flow charts showing the procedure of the processing when the reasoning system by knowledge activation of the present invention is applied to a plant maintenance work planning support; FIG. 10 is a flow chart of an approximate rule generation part; FIG. 11 is a drawing showing an example of plant system and instruments arrangement; FIG. 12 is a flow chart showing the content of the processing when the reasoning system by knowledge activation of the present invention is applied to a failure diagnosis for a plant; FIG. 13 is an illustration shown an example of a display screen for correcting the relationship between the premise part and the concluding part of the approximate rule and hierarchy composition of the target system; FIG. 14 is a flow chart of the above described correction; FIGS. 15 (a) and 15 (b) are illustrations for explanation of the display screen change; FIG. 16 is a figure showing an example of corrected rule; and FIG. 17 is an example of the rule prepared by changing content of a conventional rule without using the detailed reasoning. DETAILED DESCRIPTION OF THE EMBODIMENTS FIG. 1 is a composing diagram of the reasoning system by knowledge activation of the present invention. In FIG. 1, 1 is a computing apparatus, 2 is input/output devices, 3 and 4 are memories, and 5 is a plant. In the computing apparatus 1, an input/output processor 6 for illustrating processing content of the computer program, a judging processor 7, an approximate rule executer 8, a plant data storage 9, a detailed rule executer 10, and an approximate rule generator part are included. All of the members described above show the content executed in the computing apparatus 1 with blocks. The memory 3 stores the approximate rule. The memory 4 stores detailed rule, the frame defined constitution of the object system and characteristics of component devices, and a program for executing procedure processing. In the above described drawings, arrow-headed real lines show flow of control, and arrow-headed dashed lines show flow of information. The input/output processor 6 processes the input from the input/output devices 2, and starts the judging processor 7. The input/output processor 6 also transmits the results processed to at the approximate rule executer 8 and detailed rule executer 10 to the input/output devices 2 as outputs. The content of the input and the output is explained later in detail. The judging processor 7 determines whether any approximate rule which coincides with the input condition exists or not, and if it exists, it starts the approximate rule executer 8, but if it does not exist, it starts the detailed rule executer 10. The approximate rule executer 8 executes the concluding part of the approximate rule. The detailed rule executer 10 executes detailed reasoning relating to the object system using the detailed rule. The approximate rule generator part 11 generates approximate rule when a result which satisfies the relationship between the premise part and the concluding part of the approximate rule is obtained by detailed reasoning, and registers to the knowledge base. The data registered in the plant data storage 9 is referred to judging processor 7, approximate rule executer 8, and detailed rule executer 10. Further, when the reasoning system by knowledge activation of the present invention is used as an offline system, 5 and 6 are not necessary. Next, hierarchical expression of the object system of the present invention is explained referring to FIG. 2 diagram and FIGS. 3 and 4 frame figures. FIG. 2 is a block diagram showing part of a control rod driving hydraulic system for boiling water reactor type nuclear power plants. In the present embodiment, the system shown in FIG. 2 is divided into sub-systems such as S1, S2 etc. (hereinafter called a subsystem). The subsystems S1, S2, etc. are regarded as higher hierarchy, and such devices composing the subsystem S1 and S2 etc. such as valves V1-V18, pumps P1-P2, filters F1-F4, and heaters H1-H2 are regarded as lower hierarchy. In FIG. 2, B1-B2 are branch pipes, M1 is a flowmeter, S1-S5 are parts of control rod driving hydraulic system, and S6 is a part of recirculating system. FIG. 3 is a frame representing the higher hierarchy S1. The component devices, entrance, exit, and stop line (piping without liquid flow) of the subsystem are shown in frame. The above described frame expresses the object system with data having a three layer structure of frames, slots and values. For instance, the first line means that the values of the slot which is one of the components of the frame S1 are {B1, B2, ... F2}. The symbol {} means list construction data which store a plurality of elements. FIG. 4 shows an example of the lower hierarchy frame. The frame describes the higher hierarchy (slot name is UPPER SYSTEM) of the filter F1 , including the line (piping, same hereinafter) where the F1 is installed, input device, output device, and the names of the functions which express the relationship between input and output. FIGS. 5 and 6 show examples of rules which execute reasoning using above described data. In FIG. 5, an example of shallow knowledge, namely, an approximate rule, is shown. In the example, the following three types of approximate rules are considered. Type (1) : Output change of the subsystem is obtained from internal state change of the subsystem. Type (2) : Output change of the subsystem is obtained from input change of the subsystem. Type (3) : Internal state change of the subsystem is obtained from input change of the subsystem. FIG. 5 is the rule of the above described type (2). The rule comprises rule name, premise parts ("if"parts), and concluding parts ("then"parts). In the premise parts, a conditional proposition for referring slot values of the frame is described, and, in the concluding parts, an order for renewal of the slot values of the frame is described. In the premise parts ("if"parts), stop line of the subsystem S2 and input change of B3 which is an entrance of the subsystem (take change of flow rate, temperature, and pressure for the input change 1, 2 and 3) are described. In the concluding parts ("then"parts), an order to be written in B4 which is an exit of the subsystem is described. The mark "[+]" written by the slot values means "increment", and "[0]" means "no change". B4 is the frame name. The mark "@" signifies the name of the slot. For instance, the first line condition means "the value of STOP -- LINE slot of the frame S2 includes the PIPING 04". And the operator means "equal", and "*" means (hereinafter in the same manner). By using the approximate rule shown in FIG. 5, the output change of B4, the exit of the subsystem, can be induced directly from the input change of B3, the entrance of the subsystem, and accordingly, it is not necessary to calculate input and output of the internal devices. Therefore, the reasoning can be achieved fast. If an approximate rule does not exist, the detail rule explained subsequently is executed, and the approximate rule is generated. In FIG. 6, an example of the detail rule is shown. The rule is for execution a function "exec-func" which is described in ?DEVICE -- X frame using device name (?DEVICE -- X) and its input change ?X1, ?X2 and ?X3 as parameters when the input change of any device (?DEVICE -- X) is calculated and the output change is not defined. The mark "?" means a variable. A function "exec-func" calculates the output change from the input change of the ?DEVICE -- X. FIG. 7 is an example of the rule for generating an approximate rule, and the approximate rule is generated when a result which satisfies the relationship between the premise part and the concluding part of the approximate rule is obtained. The rule is for execution of the "make-rule 1" function using ?DEVICE -- X and ?DEVICE -- Y as parameters when ?DEVICE -- X is the entrance of ?SUBSYSTEM and ?DEVICE -- Y is the exit of ?SUBSYSTEM and if both the input change of ?DEVICE -- X and the output change of ?DEVICE -- Y have been calculated. The function "make-rule" generates a rule for calculating output change of the ?DEVICE -- Y from the input change of the ?DEVICE -- X. Embodiment 1 Hereinafter, the reasoning system by knowledge activation of the present invention is explained by describing the example using the system for support of maintenance work planning for a plant. When a plurality of maintenance work is are executed in a plant, it is necessary to determine whether or not such work will have a disruptive influence upon other work, that is, whether it interferes or not. For instance, in the plant system shown in FIG. 2, for inspection of the pump P1, operation of the P1 is changed to the P2 and the inspection is executed, and subsequently, the changing work of the P2 with P1 is determined as the primary work. The inspection of the flow meter M1 is determined to be the secondary work. The primary work consists of following operation: (1) Open the valves, V7, V8 (2) Start the pump P2 (3) Stop the pump P1 (4) Close the valves, V5, V6 (5) Inspect the pump P1 (6) Open the valves, V6, V5 (7) Start the pump P1 (8) Stop the pump P2 (9) Close the valves, V7, V8 As a premise condition for execution of the secondary work, the flow rate of water to PLR pump through the valve V18 must be kept constant (change of flow rate is zero). FIG. 8 is a flow chart for judging the interference described above. At the procedures 81, 82, content and work condition of the device operation are set. In the procedure 83, a starting point of the condition change is set at the operation device, and a terminating point is set at the evaluating place of the working effect. Also, starting phenomena of the stage change propagation is set. In the above example, the valve V7, V8, and the pump P2 etc. are the starting points, and the inlet of the PLR pump is the terminating point. The procedure 84 determines whether the approximate rule which is usable for the state change propagation exists or not, and if it exists,, the approximate rule is executed by the procedure 85, but if not, the detailed reasoning at 86 is executed. By the procedure 87, the approximate rule is generated and registered in the knowledge base if a result which satisfies the relationship between the premise part and the concluding part of the approximate rule is obtained by the detailed reasoning. At the time when the propagation of the condition comes to the terminating point, the procedure 89 judges whether the state change violates the working condition (flow rate is zero in this example) or not, that is, whether the interference exists or not. The above described procedures are repeated for all the above mentioned device operations, and the result is displayed by the procedure 803. FIG. 9 is a flow chart of reasoning using detailed knowledge, namely, detailed reasoning part. In accordance with FIG. 9(a), if there are devices for which input changes have been calculated but output changes have not been defined, output change of the devices are then calculated. In accordance with FIG. 9(b), if there are devices for which output changes have been calculated and input changes of the subsequent downstream side device (the output device defined OUTPUT -- DEVICE -- 1 slot of the frame shown in FIG. 4) are not yet defined, output change of the former is placed as the input change for the latter. By repeating the procedures in FIG. 9(a) and 9(b), the state change caused by the operation of the starting device can be propagated to the downstream side device successively. The above described procedures should not be applied to such device in which liquid is not flown through a closed valve. FIG. 10 is a flow chart of a rule generation part. The rule generation part judges whether or not input change of such an entrance device as the subsystem S3, S4 etc. and output change of an exit device have been calculated by using the rule such as the example shown in FIG. 7. If it has been calculated, the approximate rule such as the example shown in FIG. 5d is generated. That is, the procedure 101 and 102 in FIG. 10 execute the above described judgement, and the procedure from 103 to 106 generates the rule which describes name of the rule, name of the subsystem, stop line, name of the entrance device, input change in the premise part, name of the exit device and output change in the concluding part, and the rule is written into the approximate rule storage shown in FIG. 1. The rule generation function, such as the example shown in FIG. 7, executes the above described procedures from 103 to 106. In the above described processes for interference judgement, the same processes appear repeatedly in regard to propagation of state change at the subsystem S3 and S4 etc. That is, open-close operation of the valves in the above described device operation (1), (4), (6) and (9) cause fluctuation of flow rate at the inlet of the subsystem S3 (outlet the S2). Moreover, starting of the pumps of (2) and (7) increments the flow rate, and stopping the pumps of (3) and (8) decrease the flow rate. When same state changes appear repeatedly in this manner, it is necessary to execute detailed reasoning for the first state change propagation, but since the approximate rule can be used for the second and subsequent state change propagations, the processing can be accelerated. Embodiment 2 Next, an embodiment of application of the reasoning system by knowledge activation of the present invention to diagnosis of a plant is explained. In FIG. 11, T1 and T2 are subsystems, and MA, MB and MC are instruments. An example is considered, in which an observed value of the instrument MC indicates an abnormality and the causes are investigated. If the abnormality of the device propagates to the downstream side, the device which causes the abnormality of the observed value of the MA exists at T1, T2 or further upstream side. FIG. 12 is a flow chart for investigating the possible causes of the abnormality. The flow chart shown in FIG. 12 shows procedures for specifying the causes of the abnormality by determining the instruments located upstream side of the instrument which record the abnormality, propagating the state change to the downstream side based on the observed value of the upstream side instruments, and judging whether a result coinciding with the abnormality can be obtained or not. For instance, if the change of the observed value by the MB is very small and abnormality of the observed value by the MA is not detectable by the observed value by the MB, the device which causes the abnormality is narrowed to the device in the subsystem T2. In the above described diagnosis process, the process 126 propagates the state change in blocks of a subsystem by using the approximate rule. If the approximate rule does not exist, the process 127 propagates the state change to each of the devices by using the detailed rule, and then, the process 128 generates the approximate rule. As the above explanation clarifies, the reasoning system by knowledge activation of the present invention is able to generate the approximate rule by itself, and it is not necessary to prepare the previous users. Further, the content of the processing by the approximate rule can be easily changed by correcting the hierarchical composition of the object system, or correcting the condition which should be satisfied by the premise part and the concluding part of the approximate rule. An example of a CRT display screen composition for execution of the above described correction is shown in FIG. 13. In the example, a window is arranged for correction of the hierarchical composition at the upper part of the screen. For correction of the hierarchical composition, change the range (a rectangular frame) of the subsystem such as S1, S2 etc., and then correct the content of the frame depending on the result of the range change. Examples of a flow chart and the content of the correction for the diagram correction are shown in FIGS. 14 and 15. In FIG. 14, the procedure 141 eliminates the rectangular frame which shows the range of the route displayed on FIG. 13 by order of the user. Subsequently, the name of the subsystem and frame corresponding to the eliminated rectangular frame is eliminated by the procedures 142 and 143. At this point, the diagram shown on FIG. 13 becomes as FIG. 15 (a). The processes 144 and 145 set a newly defined range of the subsystem and name of the frame by order of the user. Then the diagram shown on FIG. 13 becomes as FIG. 15 (b). The procedures 146 and 147 determine which devices are included in the range of the subsystem SA which is designated in FIG. 15 (b), namely the components of the subsystem, and which device is located at the entrance and exit of the subsystem, and describe the name of each device in the COMPONENTS slot, ENTRANCE slot, and EXIT slot of the frame SA. The content of the prepared frame is displayed on the window shown at upper right of FIG. 13. A window for correcting a condition to be satisfied by the premise part and concluding part of the approximate rule is arranged at the lower region of FIG. 13. The processing content of the approximate rule can be changed by correcting the frame name, slot name, value of the slot, which are referred and renewed in the rule, and name of the function to execute the process of the procedure. For instance, the rule shown in FIG. 7 describes in the processing part for preparation of the approximate rule using the function "make -- rule -- 1" under a condition that input change of the entrance device and output change of the exit device have been calculated. The content of the rule is corrected as shown in FIG. 16, for example, in the window at the lower region of FIG. 13. The rule shown in FIG. 16 indicates preparation of the type (1) rule which is one of the approximate rules classified into three types previously, namely, the rule for obtaining output change of the subsystem (output change of the exit device of the subsystem) from the change of internal state change of the subsystem (output change of the operated device). Additionally, the user designates whether the corrected rule is newly registered or the prior uncorrected rule is replaced with the corrected rule. Furthermore, the reasoning system by knowledge activation of the present invention is able to prepare a new rule by extracting changeable conditions from the premise part of the approximate rule and changing the conditions. For instance, FIG. 17 is an example of changing the stop line from PIPING -- 04 to PIPING -- 03 among condition items of the rule shown in FIG. 5. Such a rule as described above is easily generated by using symmetrical feature of the system construction without using detailed reasoning. And, from the characteristics of input/output of the device, it is possible to generate new rules by extracting rules which are able to consist even in the case when an operation to change the value of the INPUT -- CHANGE 1 from "[+]" to "[-]" is executed and changing the condition of the rule. Further, when a plurality of different condition items which lead to same conclusion exist in the approximate rule, it is possible to unite the items together and convert the items to a condition item of higher grade concept. For instance, in the device of the subsystem S2 shown in FIG. 2, even when the value V7 is closed or the case when the value V8 is closed, behavior of the subsystem S2 makes no difference. Therefore, the condition can be represented by the condition that the PIPING -- 04, in which V7 and V8 are installed, is a stop line. The frame and the rule exampled previously are represented in this manner.

4y

FIELD OF THE INVENTION The invention relates to an improved diversion device between a faucet and a shower head, which not only is able to shut off the water but also to divert the direction of water flow, either to a shower head or a spout, and which has an enhanced shut-off effect and prolonged service life. BACKGROUND OF THE INVENTION The common-used bathroom shower device usually comprises three main parts: a shower head, a shower-divert device and a spout. The shower-divert device connects two source water pipes: one for the hot-water and the other for the cold, and its function is expected to be able to not only shut off, but also divert the water, either to the shower head or to the spout. Such shower-divert devices in the present market could be divided into two main varieties: double-knobbed and uni-handled. Though much easier to operate, the later has its defects such as: a) it is much more expensive; b) it is so complex in structure that when inoperative, it has to be repaired by professionals, which means higher maintenance costs; c) most uni-handled shower-diverts device are made of fine porcelain which is easier to be damaged by low quality water, in this case, the conventional rubber seal is not only much cheaper, but also much safer; and, d) since it has been on the market for a very short time, its components are under standardized and it may be difficult to find repair parts. It will be very useful if a high control efficiency double-knobbed shower divert device could be developed. SUMMARY OF THE INVENTION The main objective of the invention is to provide an improved diversion device which can shut off the water as well divert it to either a shower head or a spout without having to resist the pressure of the water therefor being light and handy in operation. The other objective of the invention is to provide an improved diversion device which can continue to provide the water at the previous temperature after the shower divert is shut off. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of a preferred embodiment of the present invention; FIG. 2 is a top view in partial section of the device in FIG. 1; FIG. 3 is a side view in partial section of the device in FIG. 1; FIG. 4 is an exploded perspective view of a diversion tube and a control shaft of the device in FIG. 1; FIG. 5 is a side plan view of the diversion tube and the control shaft; FIGS. 5A-5E are cross sections when the device in FIG. 1 is in the OFF position; FIG. 6 is a side plan view of the division tube and the control shaft; FIGS. 6A-6E are cross sections when the control shaft diverts water to the spout; FIG. 7 is a side plan view of the division tube and the control shaft FIGS. 7A-7E are cross sections when the control shaft diverts water to the shower head; FIG. 8 is an exploded side plan view of a cut-off valve assembled at the inlet of the source water in accordance with the present invention; FIG. 9 is a side plan view in partial section of the cut-off valve shown in FIG. 8; and FIG. 10 is a side plan view in partial section of the cut-off valve in FIG. 8 in operation. DESCRIPTION OF THE PREFERRED EMBODIMENT FIG. 1 is a preferred embodiment of a diversion device. Like a conventional diversion device, the present invention connects two source water pipes: one (14) for the hot water and the other (12) for the cold. The two pipes join to a central housing (16). On the front of the housing (16) is a knob (18) which is use to control the flow of or to divert the water to either the shower head or to the spout. With reference to FIG. 2, the inner structure of the housing (16) is shown. A diversion tube (20) is held within the housing (16) with a watertight fit. The inner chamber of the housing (16) is divided into four sections by the diversion tube (20) and corresponding walls: an upper outlet chamber (162), two inlet chambers (160) and a lower outlet chamber (164). The four chambers are separated by two O-rings (260) respectively installed in two grooves (26) so that the water can not flow within the space defined by the housing's (16) inner surface and the diversion tube's (20) outer surface. The upper outlet chamber (162) is connected to the shower head (not shown) and the lower outlet chamber (164) is connected to the spout (now shown). In the diversion tube (20), corresponding to each above-mentioned three sections, there are an upper outlet hole (202), a plurality of inlet holes (200) and a lower outlet hole (204). FIG. 4 shows the diversion tube (20), the control shaft (30) and their relationship. Defined in the diversion tube 20 are a shoot opening (22) and a first threaded locking hole (24). The control shaft (30) is rotatably inserted into the diversion tube (20) with the watertight fit maintained by two O-rings (380) each mounted in a groove (38) respectively. Provided between the bases of said two grooves (38) and aligned with the inlet holes (200) and either the upper outlet (202) or lower outlet (204) holes defined in the diversion tube (20) is an aqueduct (32). This aqueduct (32) is defined by a thin rectangular plate connected to a diameter of said groove bases respectively. A semicircular cross section shielder (324) is attached on the plate's back surface, and here in this embodiment it is attached by a plurality of receiving openings (320). Longitudinally corresponding to the shoot opening (22), an opening (34) is defined in the control shaft (30) for receiving a stop bolt (340) which limits the control shaft's rotation with respect to the diversion tube (20). Corresponding to the first locking hole (24), a second opening (36) is defined in the control shaft (30). When the diversion tube (20) and the control shaft (30) are assembled together, a spring (360) and a positioning ball (362) are put into the two aligned openings (24, 36) and are sealed therein by a plug (240). FIGS. 5, 6 and 7 show relative positions of the control shaft (30) and the division tube (20) when the control shaft (30) is aligned to perform the three functions: "shut", divert to "spout" and divert to "shower head", respectively. In FIG. 5, the side view of the assembled diversion tube (20) and control shaft (30), together with accompanying cross sections from five different positions, shows the situation when the control shaft (30) is turned to "shut". FIG. A--A shows that the upper outlet hole (202) in the diversion tube (20) is closed by the shield (324); FIG. B--B shows that the inlet holes (200) in the diversion tube (20) are open to the aquaduct (32); FIG. C--C shows that the lower outlet hole (204) in the diversion tube (20) is also closed by the shield (324); FIG. D--D shows that the stop bolt (340) is at the center of the shoot opening (22), and it can be turned to left or right; and, FIG. E--E shows that under the force of the spring (360), the positioning ball (362) is pushed into a space of a certain depth left by the plug (240) thus providing a positioning force on the control shaft (30) with respect to the diversion tube (20). Under these conditions, all the outlet holes are closed so the shower-divert is "shut off". In FIG. 6, the control shaft is turned to the position of "spout". FIG. A--A shows that the upper outlet hole (202) in the diversion tube (20) is closed by the shield (324); FIG. B--B shows that the inlet holes (200) in the diversion tube (20) are open; FIG. C--C shows that the lower outlet hole (204) is also open; FIG. D--D shows that the stop bolt (340) is at the right most end of the stop groove (22), a position easy to identify by a user; FIG. E--E shows that the spring (360) is compressed and the positioning ball (362) is pushed by the spring against the inner surface of the diversion tube. Under these conditions, the inlet hole (200) and the lower outlet hole (204) which connects to the lower outlet chamber (164) which connects to the pipe leading to the spout is open yet the upper outlet hole (202) is closed, so the source water will be diverted to the spout. In FIG. 7, the control shaft 30 is turned to the position for "shower head". FIG. A--A shows that the upper outlet hole (202) in the diversion tube 20 is open; FIG. B--B shows that the inlet hole (200) in the diversion tube (20) is open; FIG. C--C shows that the lower outlet hole (204) is closed by the shield (324); FIG. D--D shows that the stop bolt (340) is at the left most end of the shoot opening (22); FIG. E--E shows that the spring (360) is compressed and the positioning ball (362) is pushed by the spring against the inner surface of the diversion tube (20). FIGS. 8, 9 and 10 show a cut-off valve device (40) and its principle of operation. The cut-off valve device is used between the shower-divert device (10) (shown in FIG. 1) and the water pipe (12, 14) (here the cold-water tube) to prevent flow of the water from the shower-divert device (10) back into the water pipe (12, 14) when the shower divert device (10) is shut off. FIG. 8 shows that the cut-off device comprises a cut-off valve (40) and a valve cover (122) covered thereon. With reference to FIG. 9, the cut-off valve is a small barrel-like device comprising therewithin: a hollowed-out frame (400) fixed on the inner face of the barrel with a central opening, a shaft (420) slidably inserted in said central opening, a cylinder (42) connected onto the free end of said shaft at the cylinder's center, a spring (44) covering around the shaft and fixed onto said hollowed-out frame (400) at one end and onto the cylinder (42) at the other end. When the water is shut off, the cylinder (42) will close the inlet hole defined in the bottom face, facing the side of the shower divert, of the cut-off valve device under the force of the spring thus preventing the water from flowing back into the water tube. And also with reference to FIG. 10, when the source water is turned on, the cut-off valve will open because the cylinder (42) is pushed back by the pressure of the water.

4y

This is a continuation of application Ser. No. 08/833,067, filed Apr. 3, 1997, now allowed which is a con of Ser. No. 08/587,698 Aug. 17, 1996 Abn and a con of Ser. No. 08/186,157 Aug. 4, 1994 Abn. SUMMARY OF THE INVENTION This invention relates to novel ophthalmic compositions comprising a topical carbonic anhydrase inhibitor of structure: wherein A, Z, R 1 and X are as hereinafter defined, or an ophthamologically acceptable salt thereof and a β-adrenergic antagonist selected from betaxolol, bufenolol, carteolol, levobunolol, metipranolol, and timolol, or an ophthalmologically acceptable salt thereof. The invention is also concerned with the use of the novel ophthalmic compositions in the treatment of ocular hypertension. More particularly, it relates to such ophthalmic combinations and their use in the treatment of ocular hypertension and glaucoma, wherein the β-adrenergic antagonist is 1-(tert-butylamino)-3-[(4-morpholino-1,2,5-thiadiazol-3-yl)oxy]-2-propanol, or an ophthalmologically acceptable salt thereof which name includes the (S)-(−)- and (R)-(+)-enantiomers and any mixtures thereof, including racemic material. The (S)-(−)-enantiomer is generally known as timolol. BACKGROUND OF THE INVENTION Glaucoma is a degenerative disease of the eye wherein the intraocular pressure is too high to permit normal eye function. As a result, damage may occur to the optic nerve head and result in irreversible loss of visual function. If untreated, glaucoma may eventually lead to blindness. Ocular hypertension, i.e., the condition of elevated intraocular pressure without optic nerve head damage or characteristic glaucomatous visual field defects, is now believed by the majority of ophthalmologists to represent merely the earliest phase in the onset of glaucoma. Many of the drugs formerly used to treat glaucoma proved not entirely satisfactory. The early methods of treatment of glaucoma employing pilocarpine produced undesirable local effects that made this drug, though valuable, unsatisfactory as a first line drug. More recently, clinicians have noted that many β-adrenergic antagonists are effective in reducing intraocular pressure. While many of these agents are effective for this purpose, there exist some patients with whom this treatment is not effective or not sufficiently effective. Many of these agents also have other characteristics, e.g., membrane stabilizing activity, that become more apparent with increased doses and render them unacceptable for chronic ocular use. The β-adrenergic antagonist (S)-1-(tert-butylamino)-3-[(4-morpholino-1,2,5-thiadiazol-3-yl)oxy]-2-propanol, timolol, was found to reduce intraocular pressure and to be devoid of many unwanted side effects associated with pilocarpine and, in addition, to possess advantages over many other β-adrenergic antagonists, e.g., to be devoid of local anesthetic properties, to have a long duration of activity, and to display minimal loss of effect with increased duration of dosing. Although pilocarpine and β-adrenergic antagonists reduce intraocular pressure, none of these drugs manifests its action by inhibiting the enzyme carbonic anhydrase, and thus they do not take advantage of reducing the contribution to aqueous humor formation made by the carbonic anhydrase pathway. Agents referred to as carbonic anhydrase inhibitors block or impede this inflow pathway by inhibiting the enzyme carbonic anhydrase. While such carbonic anhydrase inhibitors are now used to treat intraocular pressure by systemic routes, they thereby have the distinct disadvantage of inhibiting carbonic anhydrase throughout the entire body. Such a gross disruption of a basic enzyme system is justified only during an acute attack of alarmingly elevated intraocular pressure, or when no other agent is effective. For several years, the desirability of directing the carbonic anhydrase inhibitor to only the desired ocular target tissue has been recognized. Because carbonic anhydrase inhibitors have a profound effect in altering basic physiological processes, the avoidance of a systemic route of administation serves to diminish, if not entirely eliminate, those side effects caused by inhibition of carbonic anhydrase such as metabolic acidosis, vomiting, numbness, tingling, general malaise and the like. Topically effective carbonic anhydrase inhibitors are disclosed in U.S. Pat. Nos. 4,386,098; 4,416,890; 4,426,388; 4,668,697; and 4,863,922 and PCT Publication WO 91/15486. As yet, no topically effective carbonic anhydrase inhibitors are generally available for clinical use. Thus, when a carbonic anhydrase inhibitor is combined with a β-adrenergic antagonist, there is experienced an effect that reduces the intraocular pressure below that obtained by either medicament individually. The activity of carbonic anhydrase inhibitors currently under development wanes 6 to 8 hours post-dose, meaning that as single agents these carbonic anhydrase inhibitors must be administered at least three times a day to maintain the desired lowering of intraocular pressure. The combination of this invention maintains the desired lowering of intraocular pressure for a full twelve hours. Because of this increased duration of action, the combination disclosed herein is effective when administered only twice a day. Patient compliance is anticipated to be greater with twice a day administration than with three times a day administration. The use of oral carbonic anhydrase inhibitors in combination with the topical β-adrenergic antagonist timolol and the resulting multiplicity of their effects is disclosed in Berson et al., American Journal of Ophthalmology 1981, 92, 788-791. However, the combination of an oral carbonic anhydrase inhibitor with a topical β-adrenergic antagonist presents two disadvantages. The first disadvantage is that the systemic use of a carbonic anhydrase inhibitor inhibits carbonic anhydrase throughout the body and exerts the same profound negative effects on basic metabolism whether it is used alone or in combination with a topical β-adrenergic antagonist. Secondly, there is poor patient compliance with simultaneous administration of both an oral and topical medicament. The combination disclosed herein is effective either by co-administration of the medicaments in one solution or as a combined therapy achieved by prior administration of either the carbonic anhydrase inhibitor or the β-adrenergic antagonist followed by administration of the other solution. The use of a single solution containing both active medicaments is preferred. The combination of this invention is suggested in U.S. Pat. No. 4,863,922, but a precise formulation of the relative combination of medicaments to give effective reduction of intraocular pressure is neither taught nor disclosed therein. There exists a patient population insufficiently responsive to available β-adrenergic antagonists who will benefit from the combination disclosed herein. Because of the combined effect of the β-adrenergic antagonist and the carbonic anhydrase inhibitor, these otherwise refractory patients can obtain a marked beneficial reduction in intraocular pressure from such a combination. Furthermore, there exists a patient population who will benefit from a combination where the minimal dosage of one or both of the medicaments is employed, thus minimizing the possibility of the occurrence of undesirable effects of one or both of the medicaments which would be more likely to become apparent with chronic use at the higher dosage. DETAILED DESCRIPTION OF THE INVENTION The novel ophthalmic compositions of this invention comprise a therapeutically effective amount of a topical carbonic anhydrase inhibitor and a β-adrenergic antagonist. The topical carbonic anhydrase inhibitor of the novel composition has the structural formula: or an ophthalmologically acceptable salt thereof wherein: A is carbon or nitrogen, preferably carbon; Z is —NHR or —OR; R is C 1-6 alkyl, either straight or branched chain, preferably C 2-4 alkyl such as ethyl, propyl or isobutyl; R 1 is (a) hydrogen, (b) C 1-3 alkyl, preferably methyl, ethyl or n-propyl, or (c) C 1-4 alkoxy-C 1-4 alkyl, preferably methoxypropyl; and X is —S(O) 2 — or —C(O) 2 —. The carbon atoms to which Z and R 1 are bonded may be chiral. When named according to absolute configuration, e.g., (R,S) or (S,S), the first letter represents the chirality the carbon atom to which Z is bonded and the second letter represents the charality of A when A is carbon. The carbonic anhydrase inhibitors of this invention accordingly may be used as diastereomeric mixtures or single enantiomers or as racemic mixtures. The β-adrenergic antagonist of the novel composition is selected from betaxolol, bufenolol, carteolol, levobunolol, metipranolol, and timolol, or an ophthalmologically acceptable salt thereof. Most of the β-adrenergic antagonists and carbonic anhydrase inhibitors recited above have at least one asymmetric carbon atom and accordingly may exist as diastereomers or (+)- or (−)-enantiomers. This invention contemplates the use of any of the diastereomers or enantiomers or mixtures thereof including racemic forms. The preferred β-adrenergic antagonist for use in the novel composition of this invention is timolol as its maleate salt. The novel ophthalmic formulations of this invention comprise about 0.05 to 5% (w/w) of carbonic anhydrase inhibitor, usually about 0.5 to 3% (w/w) and about 0.01 to 1% (w/w) of β-adrenergic antagonist, preferably about 0.1 to 0.5% (w/w) to be administered on a 1 to 2 times a day schedule. The novel method of this invention comprises the topical ocular administration of about 0.025 to 5 mg per day, preferably about 0.25 to 3 mg per day, of carbonic anhydrase inhibitor and concomitant, prior, or previous administration of about 0.005 to 1 mg per day, preferably about 0.05 to 0.5 mg per day, of β-adrenergic antagonist to each eye. As a unit dosage, between 0.025 and 2.5 mg of the carbonic anhydrase inhibitor and 0.005 to 0.5 mg of the β-adrenergic antagonist are applied to the eye; preferably, 0.25 to 1.5 mg of the carbonic anhydrase inhibitor and 0.05 to 0.25 mg of the β-adrenergic antagonist. Suitable subjects for the administration of the formulation of the present invention include primates, man and other animals, particularly man and domesticated animals such as cats and dogs. For topical ocular administration the novel formulations of this invention may take the form of solutions, gels, ointments, suspensions or solid inserts, formulated so that a unit dosage comprises a therapeutically effective amount of each active component or some submultiple thereof. Typical ophthalmologically acceptable carriers for the novel formulations are, for example, water, mixtures of water and water-miscible solvents such as lower alkanols or aralkanols, vegetable oils, polyalkylene glycols, petroleum based jelly, ethyl cellulose, ethyl oleate, carboxymethylcellulose, polyvinylpyrrolidone, isopropyl myristate and other conventionally employed acceptable carriers. The pharmaceutical preparation may also contain non-toxic auxiliary substances such as emulsifying, preserving, wetting agents, bodying agents and the like, as for example, polyethylene glycols 200, 300, 400 and 600, carbowaxes 1,000, 1,500, 4,000, 6,000 and 10,000, antibacterial components such as quaternary ammonium compounds, phenylmercuric salts known to have cold sterilizing properties and which are non-injurious in use, thimerosal, benzalkonium chloride, methyl and propyl paraben, benzyldodecinium bromide, benzyl alcohol, phenylethanol, buffering ingredients such as sodium chloride, sodium borate, sodium acetate, or gluconate buffers, and other conventional ingredients such as sorbitan monolaurate, triethanolamine, polyoxyethylene sorbitan monopalmitylate, dioctyl sodium sulfosuccinate, monothioglycerol, thiosorbitol, ethylenediamine tetra-acetic acid, and the like. Additionally, suitable ophthalmic vehicles can be used as carrier media for the present purpose including conventional phosphate buffer vehicle systems, isotonic boric acid vehicles, isotonic sodium chloride vehicles, isotonic sodium borate vehicles and the like. The formulation may also include a gum such as gellan gum at a concentration of 0.1% to 2% by weight so that the aqueous eyedrops gel on contact with the eye, thus providing the advantages of a solid ophthalmic insert as described in U.S. Pat. No. 4,861,760. The pharmaceutical preparation may also be in the form of a solid insert such as one which after dispensing the drug remains essentially intact as described in U.S. Pat. Nos. 4,256,108; 4,160,452; and 4,265,874; or a bio-erodible insert that either is soluble in lacrimal fluids, or otherwise disintegrates as described in U.S. Pat. No. 4,287,175 or EPO publication 0,077,261. BRIEF DESCRIPTION OF THE DRAWING FIG. 1 shows the effect of compound I over Timolol. The following examples of ophthalmic formulations are given by way of illustration. EXAMPLE 1 SOLUTION COMPOSITION I II III (S,S)-(−)-5,6-dihydro-4-ethyl- 22.26 g 22.26 g 1.113 g amino-6-methyl-4H-thieno- [2,3b]thiopyran-2-sulfonamide- 7,7-dioxide monohydrochloride (S)-(−)-1-( tert -butylamino)- 6.834 g 1.367 g 6.834 g 3-[(4-morpholino-1,2,5- thiadiazol-3-yl)oxy]-2- propanol maleate Sodium citrate.2H 2 O 2.940 g 2.940 g 2.940 g Benzalkonium Chloride 0.075 g 0.075 g 0.075 g Hydroxyethylcellulose  5.00 g  5.00 g  5.00 g Sodium hydroxide q.s. pH = 6.0 pH = 6.0 pH = 6.0 Mannitol 16.00 g 21.00 g 35.90 g Water for injection q.s. ad.  1000 g  1000 g  1000 g The active compounds, sodium citrate, benzalkonium chloride (in a 50% W/W solution), and mannitol are dissolved in approximately 400 mL water for injection in a tared and sterile vessel. The pH of the composition is adjusted to 6.0 by addition of 0.2 N sodium hydroxide solution, and water for injection is added until the weight of composition equals 750 g. The composition is sterilized by filtration, pushing the solution with a 2 bar pressure of 0.45 micron filtrated nitrogen. Then 250 g of a 2% hydroxyethylcellulose autoclaved solution is added and the obtained solution is homogenized by stirring with a magnetic stirring bar. The solution is aseptically subdivided into 3.5 mL aliquots and sealed. EXAMPLE 2 SOLUTION COMPOSITION I II III (S,S)-(−)-5,6-dihydro-4-ethyl- 1.0 mg 1.5 mg 0.5 mg amino-6-methyl-4H-thieno- [2,3b]thiopyran-2-sulfonamide- 7,7-dioxide 4-[2-hydroxy-3-(1-methylethyl)- 0.3 mg 0.2 mg 0.4 mg amino]-propoxy]-2,3,6- trimethylphenol-1-acetate Monobasic sodium phosphate Quantity sufficient 2H 2 O to give Dibasic sodium phosphate.12H 2 O final pH 5.5-6.0 Benzalkonium chloride 0.10 mg  0.10 mg  0.10 mg  Polysorbate 80 0.2 mg 0.2 mg 0.2 mg Water for injection q.s. ad. 1.0 mL 1.0 mL 1.0 mL The active compounds, phosphate buffer salts, benzalkonium chloride, and Polysorbate 80 are added to and suspended or dissolved in water. The pH of the composition is adjusted to 5.5-6.0 and diluted to volume. The composition is rendered sterile by filtration through a sterilizing filter. EXAMPLE 3 SOLUTION COMPOSITION I II trans-5,6-dihydro-4-ethylamino- 1.7 mg 0.8 mg 6-methyl-4H-thieno[2,3b]thiopyran- 2-sulfonamide-7,7-dioxide 1-[4-[2-(cyclopropylmethoxy)- 0.3 mg 0.2 mg ethyl]phenoxy]-3-(1-methylethyl)- amino]-2-propanol Monobasic sodium phosphate.2H 2 O 9.5 mg 9.5 mg Dibasic sodium phosphate.12H 2 O 28.5 mg  28.5 mg  Benzalkonium chloride 0.10 mg  0.10 mg  Sodium hydroxide q.s. pH 6.0 pH 6.0 Water for injection q.s. ad. 1.0 mL 1.0 mL The active compounds, phosphate buffer salts, and benzalkonium chloride are added to and dissolved in water. The pH of the composition is adjusted to 6.0 with sodium hydroxide and the final solution is diluted to volume. The solution is rendered sterile by filtration through a sterilizing filter. EXAMPLE 4 SOLUTION COMPOSITION I II III (S,S)-(−)-5,6-dihydro-4-propyl- 21.0 g  21.0 g  1.5 g amino-6-methoxypropyl-4H-thieno- [2,3b]thiopyran-2-sulfonamide- 7,7-dioxide monohydrochloride (S)-(−)-1-( tert -butylamino)- 6.8 g 1.3 g 6.8 g 3-[(4-morpholino-1,2,5- thiadiazol-3-yl)oxy]-2- propanol maleate Sodium citrate.2H 2 O 2.9 g 2.9 g 2.9 g Benzalkonium Chloride 0.075 g  0.075 g  0.075 g  Hydroxyethylcellulose 5.0 g 5.0 g 5.0 g Sodium hydroxide q.s. pH = 6.0 pH = 6.0 pH = 6.0 Mannitol 35.9 g  35.9 g  35.9 g  Water for injection q.s. ad. 1000 g    1000 g    1000 g    The active compounds, sodium citrate, benzalkonium chloride (in a 50% W/W solution), and mannitol are dissolved in approximately 400 mL water for injection in a tared and sterile vessel. The pH of the composition is adjusted to 6.0 by addition of 0.2 N sodium hydroxide solution and water for injection is added until the weight of composition equals 750 g. The composition is sterilized by filtration, pushing the solution with a 2 bar pressure of 0.45 micron filtrated nitrogen. Then 250 g of a 2% hydroxyethylcellulose autoclaved solution is added and the obtained solution is homogenized by stirring with a magnetic stirring bar. The solution is aseptically subdivided into 3.5 mL aliquots and sealed. EXAMPLE 5 SOLUTION COMPOSITION I II III (S,S)-(−)-5,6-dihydro-4-propylamino- 1.0 mg 1.5 mg 0.5 mg 6-methoxypropyl-4H-thieno[2,3b] thiopyran-2-sulfonamide-7,7- dioxide 4-[2-hydroxy-3-(1-methylethyl)- 0.3 mg 0.2 mg 0.4 mg amino]propoxy]-2,3,6- trimethylphenol-1-acetate Monobasic sodium phosphate.2H 2 O Quantity sufficient Dibasic sodium phosphate.12H 2 O to give final pH 5.5-6.0 Benzalkonium chloride 0.10 mg  0.10 mg  0.10 mg  Polysorbate 80 0.2 mg 0.2 mg 0.2 mg Water for injection q.s. ad. 1.0 mL 1.0 mL 1.0 mL The active compounds, phosphate buffer salts, benzalkonium chloride, and Polysorbate 80 are added to and suspended or dissolved in water. The pH of the composition is adjusted to 5.5-6.0 and diluted to volume. The composition is rendered sterile by filtration through a sterilizing filter. EXAMPLE 6 SOLUTION COMPOSITION I II trans-5,6-dihydro-4-propylamino- 1.7 mg 0.8 mg 6-methoxypropyl-4H-thieno[2,3b] thiopyran-2-sulfonamide-7,7- dioxide 1-[4-[2-(cyclopropylmethoxy)ethyl]- 0.3 mg 0.2 mg phenoxy]-3-(1-methylethyl)amino]- 2-propanol Monobasic sodium phosphate.2H 2 O 9.5 mg 9.5 mg Dibasic sodium phosphate.12H 2 O 28.5 mg  28.5 mg  Benzalkonium chloride 0.10 mg  0.10 mg  Sodium hydroxide q.s. pH 6.0 pH 6.0 Water for injection q.s. ad. 1.0 mL 1.0 mL The active compounds, phosphate buffer salts, and benzalkonium chloride are added to and dissolved in water. The pH of the composition is adjusted to 6.0 with sodium hydroxide and the final solution is diluted to volume. The solution is rendered sterile by filtration through a sterilizing filter. EXAMPLE 7 SOLUTION COMPOSITION I II III (S)-(+)-5,6-dihydro-4-isobutyl- 21.0 g  21.0 g  1.5 g amino-4H-thieno[2,3b]thiopyran- 2-sulfonamide-7,7-dioxide mono- hydrochloride (S)-(−)-1-( tert -butylamino)- 6.8 g 1.3 g 6.8 g 3-[(4-morpholino-1,2,5- thiadiazol-3-yl)oxy]-2- propanol maleate Sodium citrate.2H 2 O 2.9 g 2.9 g 2.9 g Benzalkonium Chloride 0.075 g  0.075 g  0.075 g  Hydroxyethylcellulose 5.0 g 5.0 g 5.0 g Sodium hydroxide q.s. pH = 6.0 pH = 6.0 pH = 6.0 Mannitol 35.9 g  35.9 g  35.9 g  Water for injection q.s. ad. 1000 g    1000 g    1000 g    The active compounds, sodium citrate, benzalkonium chloride (in a 50% W/W solution), and mannitol are dissolved in approximately 400 mL water for injection in a tared and sterile vessel. The pH of the composition is adjusted to 6.0 by addition of 0.2 N sodium hydroxide solution and water for injection is added until the weight of composition equals 750 g. The composition is sterilized by filtration, pushing the solution with a 2 bar pressure of 0.45 micron filtrated nitrogen. Then 250 g of a 2% hydroxyethylcellulose autoclaved solution is added and the obtained solution is homogenized by stirring with a magnetic stirring bar. The solution is aseptically subdivided into 3.5 mL aliquots and sealed. EXAMPLE 8 SOLUTION COMPOSITION I II III (S)-(+)-5,6-dihydro-4-isobutyl- 1.0 mg 1.5 mg 0.5 mg amino-4H-thieno[2,3b]thiopyran- 2-sulfonamide-7,7-dioxide 4-[2-hydroxy-3-(1-methylethyl)- 0.3 mg 0.2 mg 0.4 mg amino]propoxy]-2,3,6- trimethylphenol-1-acetate Monobasic sodium phosphate.2H 2 O Quantity sufficient Dibasic sodium phosphate.12H 2 O to give final pH 5.5-6.0 Benzalkonium chloride 0.10 mg  0.10 mg  0.10 mg  Polysorbate 80 0.2 mg 0.2 mg 0.2 mg Water for injection q.s. ad. 1.0 mL 1.0 mL 1.0 mL The active compounds, phosphate buffer salts, benzalkonium chloride, and Polysorbate 80 are added to and suspended or dissolved in water. The pH of the composition is adjusted to 5.5-6.0 and diluted to volume. The composition is rendered sterile by filtration through a sterilizing filter. EXAMPLE 9 SOLUTION COMPOSITION I II (S)-(+)-5,6-dihydro-4-isobutyl- 1.7 mg 0.8 mg amino-4H-thieno[2,3b]thiopyran- 2-sulfonamide-7,7-dioxide 1-[4-[2-(cyclopropylmethoxy)- 0.3 mg 0.2 mg ethyl]-phenoxy]-3-(1-methylethyl)- amino]-2-propanol Monobasic sodium phosphate.2H 2 O 9.5 mg 9.5 mg Dibasic sodium phosphate.12H 2 O 28.5 mg  28.5 mg  Benzalkonium chloride 0.10 mg  0.10 mg  Sodium hydroxide q.s. pH 6.0 pH 6.0 Water for injection q.s. ad. 1.0 mL 1.0 mL The active compounds, phosphate buffer salts, and benzalkonium chloride are added to and dissolved in water. The pH of the composition is adjusted to 6.0 with sodium hydroxide and the final solution is diluted to volume. The solution is rendered sterile by filtration through a sterilizing filter. EXAMPLE 10 SOLUTION COMPOSITION I II (S,S)-(−)-5,6-dihydro-4-ethyl- 2.0 mg 0.2 mg amino-6-methyl-4H-thieno[2,3b]- thiopyran-2-sulfonamide-7,7- dioxide monohydrochloride (S)-(−)-1-( tert -butylamino)- 0.5 mg 0.5 mg 3-[(4-morpholino-1,2,5- thiadiazol-3-yl)oxy]-2- propanol maleate GELRITE ™ gellan gum 6.0 mg 6.0 mg Monobasic sodium phosphate.2H 2 O Quantity sufficient Dibasic sodium phosphate.12H 2 O to give final pH 5.5-6.0 Benzyldodecinium bromide 0.10 mg  0.10 mg  Polysorbate 80 0.2 mg 0.2 mg Water for injection q.s. ad. 1.0 mL 1.0 mL The active compounds, GELRITE™ gellan gum, phosphate buffer salts, benzyldodecinium bromide and Polysorbate 80 are added to and suspended or dissolved in water. The pH of the composition is adjusted to 5.5-6.0 and diluted to volume. The composition is rendered sterile by ionizing radiation. EXAMPLE 11 SOLUTION COMPOSITION I II (S)-(+)-5,6-dihydro-4-isobutyl- 3.0 mg 0.5 mg amino-4H-thieno[2,3b]thiopyran- 2-sulfonamide-7,7-dioxide (S)-(−)-1-( tert -butylamino)- 0.5 mg 0.5 mg 3-[(4-morpholino-1,2,5- thiadiazol-3-yl)oxy]-2- propanol maleate GELRITE ™ gellan gum 6.0 mg 6.0 mg Monobasic sodium phosphate.2H 2 O Quantity sufficient Dibasic sodium phosphate.12H 2 O to give final pH 5.0-6.0 Benzyldodecinium bromide 0.10 mg  0.10 mg  Polysorbate 80 0.2 mg 0.2 mg Water for injection q.s. ad. 1.0 mL 1.0 mL The active compounds, GELRITE™ gellan gum, phosphate buffer salts, benzyldodecinium bromide and Polysorbate 80 are added to and suspended or dissolved in water. The pH of the composition is adjusted to 5.0-6.0 and diluted to volume. The composition is rendered sterile by ionizing radiation. EXAMPLE 12 SOLUTION COMPOSITION I II (S,S)-(−)-5,6-dihydro-4-propyl- 2.0 mg 0.2 mg amino-6-methoxypropyl-4H- thieno[2,3b]thiopyran-2- sulfonamide-7,7-dioxide (S)-(−)-1-( tert -butylamino)- 0.5 mg 0.5 mg 3-[(4-morpholino-1,2,5- thiadiazol-3-yl)oxy]-2- propanol maleate GELRITE ™ gellan gum 6.0 mg 6.0 mg Monobasic sodium phosphate.2H 2 O Quantity sufficient Dibasic sodium phosphate.12H 2 O to give final pH 5.5-6.0 Benzyldodecinium bromide 0.10 mg  0.10 mg  Polysorbate 80 0.2 mg 0.2 mg Water for injection q.s. ad. 1.0 mL 1.0 mL The active compounds, GELRITE™ gellan gum, phosphate buffer salts, benzyldodecinium bromide and Polysorbate 80 are added to and suspended or dissolved in water. The pH of the composition is adjusted to 5.5-6.0 and diluted to volume. The composition is rendered sterile by ionizing radiation. EXAMPLE 13 SOLUTION COMPOSITION I II (R)-(−)-5,6-dihydro-4-iso- 2.0 mg 0.5 mg butylamino-4H-thieno[2,3b]-thio- pyran-2-sulfonamide-7,7-dioxide 4-[2-hydroxy-3-(1-methylethyl)- 0.5 mg 0.5 mg amino]propoxy]-2,3,6- trimethylphenol-1-acetate GELRITE ™ gellan gum 6.0 mg 6.0 mg Monobasic sodium phosphate.2H 2 O Quantity sufficient Dibasic sodium phosphate.12H 2 O to give final pH 5.5-6.0 Benzyldodecinium bromide 0.10 mg  0.10 mg  Polysorbate 80 0.2 mg 0.2 mg Water for injection q.s. ad. 1.0 mL 1.0 mL The active compounds, GELRITE™ gellan gum, phosphate buffer salts, benzyldodecinium bromide and Polysorbate 80 are added to and suspended or dissolved in water. The pH of the composition is adjusted to 5.5-6.0 and diluted to volume. The composition is rendered sterile by ionizing radiation. EXAMPLE 14 SOLUTION COMPOSITION I II cis-5,6-dihydro-4-ethylamino- 2.0 mg 0.2 mg 6-methyl-4H-thieno[2,3b]thiopyran- 2-sulfonamide-7,7-dioxide monohydrochloride 4-[2-hydroxy-3-(1-methylethyl)- 0.5 mg 0.5 mg amino]propoxy]-2,3,6- trimethylphenol-1-acetate GELRITE ™ gellan gum 6.0 mg 6.0 mg Monobasic sodium phosphate.2H 2 O Quantity sufficient Dibasic sodium phosphate.12H 2 O to give final pH 5.5-6.0 Benzyldodecinium bromide 0.10 mg  0.10 mg  Polysorbate 80 0.2 mg 0.2 mg Water for injection q.s. ad. 1.0 mL 1.0 mL The active compounds, GELRITE™ gellan gum, phosphate buffer salts, benzyldodecinium bromide and Polysorbate 80 are added to and suspended or dissolved in water. The pH of the composition is adjusted to 5.5-6.0 and diluted to volume. The composition is rendered sterile by ionizing radiation. EXAMPLE 15 SOLUTION COMPOSITION I II cis-5,6-dihydro-4-propyl- 2.0 mg 0.5 mg amino-6-methoxypropyl-4H- thieno[2,3b]thiopyran-2- sulfonamide-7,7-dioxide 4-[2-hydroxy-3-(1-methylethyl)- 0.5 mg 0.5 mg amino]propoxy]-2,3,6- trimethylphenol-1-acetate GELRITE ™ gellan gum 6.0 mg 6.0 mg Monobasic sodium phosphate.2H 2 O Quantity sufficient Dibasic sodium phosphate.12H 2 O to give final pH 5.5-6.0 Benzyldodecinium bromide 0.10 mg  0.10 mg  Polysorbate 80 0.2 mg 0.2 mg Water for injection q.s. ad. 1.0 mL 1.0 mL The active compounds, GELRITE™ gellan gum, phosphate buffer salts, benzyldodecinium bromide and Polysorbate 80 are added to and suspended or dissolved in water. The pH of the composition is adjusted to 5.5-6.0 and diluted to volume. The composition is rendered sterile by ionizing radiation. EXAMPLE 16 SOLUTION COMPOSITION I II 5,6-dihydro-4-ethylamino- 2.0 mg 0.2 mg 6-methyl-4H-thieno[2,3b]thiopyran- 2-sulfonamide-7,7-dioxide monohydrochloride 1-[4-[2-(cyclopropylmethoxy)ethyl]- 0.5 mg 0.5 mg phenoxy]-3-(1-methylethyl)amino]- 2-propanol GELRITE ™ gellan gum 6.0 mg 6.0 mg Monobasic sodium phosphate.2H 2 O Quantity sufficient Dibasic sodium phosphate.12H 2 O to give final pH 5.5-6.0 Benzyldodecinium bromide 0.10 mg  0.10 mg  Polysorbate 80 0.2 mg 0.2 mg Water for injection q.s. ad. 1.0 mL 1.0 mL The active compounds, GELRITE™ gellan gum, phosphate buffer salts, benzyldodecinium bromide and Polysorbate 80 are added to and suspended or dissolved in water. The pH of the composition is adjusted to 5.5-6.0 and diluted to volume. The composition is rendered sterile by ionizing radiation. EXAMPLE 17 SOLUTION COMPOSITION I II 5,6-dihydro-4-isobutylamino- 2.0 mg 0.5 mg 4H-thieno[2,3b]thiopyran- 2-sulfonamide-7,7-dioxide 1-[4-[2-(cyclopropylmethoxy)ethyl]- 0.5 mg 0.5 mg phenoxy]-3-(1-methylethyl)amino]- 2-propanol GELRITE ™ gellan gum 6.0 mg 6.0 mg Monobasic sodium phosphate.2H 2 O Quantity sufficient Dibasic sodium phosphate.12H 2 O to give final pH 5.5-6.0 Benzyldodecinium bromide 0.10 mg  0.10 mg  Polysorbate 80 0.2 mg 0.2 mg Water for injection q.s. ad. 1.0 mL 1.0 mL The active compounds, GELRITE™ gellan gum, phosphate buffer salts, benzyldodecinium bromide and Polysorbate 80 are added to and suspended or dissolved in water. The pH of the composition is adjusted to 5.5-6.0 and diluted to volume. The composition is rendered sterile by ionizing radiation. EXAMPLE 18 SOLUTION COMPOSITION I II 5,6-dihydro-4-propylamino- 2.0 mg 0.2 mg 6-methoxypropyl-4H- thieno[2,3b]thiopyran-2- sulfonamide-7,7-dioxide 1-[4-[2-(cyclopropylmethoxy)ethyl]- 0.5 mg 0.5 mg phenoxy]-3-(1-methylethyl)amino]- 2-propanol GELRITE ™ gellan gum 6.0 mg 6.0 mg Monobasic sodium phosphate.2H 2 O Quantity sufficient Dibasic sodium phosphate.12H 2 O to give final pH 5.5-6.0 Benzyldodecinium bromide 0.10 mg  0.10 mg  Polysorbate 80 0.2 mg 0.2 mg Water for injection q.s. ad. 1.0 mL 1.0 mL The active compounds, GELRITE™ gellan gum, phosphate buffer salts, benzyldodecinium bromide and Polysorbate 80 are added to and suspended or dissolved in water. The pH of the composition is adjusted to 5.5-6.0 and diluted to volume. The composition is rendered sterile by ionizing radiation. EXAMPLE 19 SOLUTION COMPOSITION I II III 3,4-Dihydro-4-methoxy-2-methyl- 22.26 g 22.26 g 1.113 g 2H-thieno[3,2-e]-1,2-thiazine- 6-sulfonamide-1,1-dioxide (S)-(−)-1-( tert -butylamino)- 6.834 g 1.367 g 6.834 g 3-[(4-morpholino-1,2,5- thiadiazol-3-yl)oxy]-2- propanol maleate Sodium citrate.2H 2 O 2.940 g 2.940 g 2.940 g Benzalkonium Chloride 0.075 g 0.075 g 0.075 g Hydroxyethylcellulose  5.00 g  5.00 g  5.00 g Sodium hydroxide q.s. pH = 6.0 pH = 6.0 pH = 6.0 Mannitol 16.00 g 21.00 g 35.90 g Water for injection q.s. ad.  1000 g  1000 g  1000 g EXAMPLE 20 SOLUTION COMPOSITION I II III 3,4-Dihydro-4-ethylamino-2- 22.26 g 22.26 g 1.113 g methyl-2H-thieno[3,2-e]-1,2- thiazine-6-sulfonamide-1,1- dioxide hydrochloride (S)-(−)-1-( tert -butylamino)- 6.834 g 1.367 g 6.834 g 3-[(4-morpholino-1,2,5- thiadiazol-3-yl)oxy]-2- propanol maleate Sodium citrate.2H 2 O 2.940 g 2.940 g 2.940 g Benzalkonium Chloride 0.075 g 0.075 g 0.075 g Hydroxyethylcellulose  5.00 g  5.00 g  5.00 g Sodium hydroxide q.s. pH = 6.0 pH = 6.0 pH = 6.0 Mannitol 16.00 g 21.00 g 35.90 g Water for injection q.s. ad.  1000 g  1000 g  1000 g EXAMPLE 21 SOLUTION COMPOSITION I II III 3,4-Dihydro-2-methyl-4-(2- 22.26 g 22.26 g 1.113 g methyl)propylamino-2H-thieno- [3,2-e]-1,2-thiazine-6-sulfon- amide-1,1-dioxide hydrochloride (S)-(−)-1-( tert -butylamino)- 6.834 g 1.367 g 6.834 g 3-[(4-morpholino-1,2,5- thiadiazol-3-yl)oxy]-2- propanol maleate Sodium citrate.2H 2 O 2.940 g 2.940 g 2.940 g Benzalkonium Chloride 0.075 g 0.075 g 0.075 g Hydroxyethylcellulose  5.00 g  5.00 g  5.00 g Sodium hydroxide q.s. pH = 6.0 pH = 6.0 pH = 6.0 Mannitol 16.00 g 21.00 g 35.90 g Water for injection q.s. ad.  1000 g  1000 g  1000 g EXAMPLE 22 SOLUTION COMPOSITION I II III R-(+)-3,4-Dihydro-4-ethylamino- 22.26 g 22.26 g 1.113 g 2-methyl)-2H-thieno[3,2-e]-1,2- thiazine-6-sulfonamide-1,1- dioxide hydrochloride (S)-(−)-1-( tert -butylamino)- 6.834 g 1.367 g 6.834 g 3-[(4-morpholino-1,2,5- thiadiazol-3-yl)oxy]-2- propanol maleate Sodium citrate.2H 2 O 2.940 g 2.940 g 2.940 g Benzalkonium Chloride 0.075 g 0.075 g 0.075 g Hydroxyethylcellulose  5.00 g  5.00 g  5.00 g Sodium hydroxide q.s. pH = 6.0 pH = 6.0 pH = 6.0 Mannitol 16.00 g 21.00 g 35.90 g Water for injection q.s. ad.  1000 g  1000 g  1000 g EXAMPLE 23 SOLUTION COMPOSITION I II III R-(+)-3,4-Dihydro-4-ethylamino- 22.26 g 22.26 g 1.113 g 2-(2-methoxy)ethyl-2H-thieno- [3,2-e]-1,2-thiazine-6-sulfon- amide-1,1-dioxide hydrochloride (S)-(−)-1-( tert -butylamino)- 6.834 g 1.367 g 6.834 g 3-[(4-morpholino-1,2,5- thiadiazol-3-yl)oxy]-2- propanol maleate Sodium citrate.2H 2 O 2.940 g 2.940 g 2.940 g Benzalkonium Chloride 0.075 g 0.075 g 0.075 g Hydroxyethylcellulose  5.00 g  5.00 g  5.00 g Sodium hydroxide q.s. pH = 6.0 pH = 6.0 pH = 6.0 Mannitol 16.00 g 21.00 g 35.90 g Water for injection q.s. ad.  1000 g  1000 g  1000 g EXAMPLE 24 SOLUTION COMPOSITION I II III R-(+)-3,4-Dihydro-2-(2-methoxy)- 22.26 g 22.26 g 1.113 g ethyl-4-propylamino-2H-thieno- [3,2-e]-1,2-thiazine-6-sulfon- amide-1,1-dioxide hydrochloride (S)-(−)-1-( tert -butylamino)- 6.834 g 1.367 g 6.834 g 3-[(4-morpholino-1,2,5- thiadiazol-3-yl)oxy]-2- propanol maleate Sodium citrate.2H 2 O 2.940 g 2.940 g 2.940 g Benzalkonium Chloride 0.075 g 0.075 g 0.075 g Hydroxyethylcellulose  5.00 g  5.00 g  5.00 g Sodium hydroxide q.s. pH = 6.0 pH = 6.0 pH = 6.0 Mannitol 16.00 g 21.00 g 35.90 g Water for injection q.s. ad.  1000 g  1000 g  1000 g EXAMPLE 25 SOLUTION COMPOSITION I II 3,4-Dihydro-4-methoxy-2-methyl- 2.0 mg 0.2 mg 2H-thieno[3,2-e]-1,2-thiazine- 6-sulfonamide-1,1-dioxide (S)-(−)-1-( tert -butylamino)- 0.5 mg 0.5 mg 3-[(4-morpholino-1,2,5- thiadiazol-3-yl)oxy]-2- propanol maleate GELRITE ™ gellan gum 6.0 mg 6.0 mg Monobasic sodium phosphate.2H 2 O Quantity sufficient Dibasic sodium phosphate.12H 2 O to give final pH 5.5-6.0 Benzyldodecinium bromide 0.10 mg  0.10 mg  Polysorbate 80 0.2 mg 0.2 mg Water for injection q.s. ad. 1.0 mL 1.0 mL The active compounds, GELRITE™ gellan gum, phosphate buffer salts, benzyldodecinium bromide and Polysorbate 80 are added to and suspended or dissolved in water. The pH of the composition is adjusted to 5.5-6.0 and diluted to volume. The composition is rendered sterile by ionizing radiation. EXAMPLE 26 SOLUTION COMPOSITION I II 3,4-Dihydro-4-ethylamino-2- 2.0 mg 0.2 mg methyl-2H-thieno[3,2-e]- 1,2-thiazine-6-sulfonamide- 1,1-dioxide hydrochloride (S)-(−)-1-( tert -butylamino)- 0.5 mg 0.5 mg 3-[(4-morpholino-1,2,5- thiadiazol-3-yl)oxy]-2- propanol maleate GELRITE ™ gellan gum 6.0 mg 6.0 mg Monobasic sodium phosphate.2H 2 O Quantity sufficient Dibasic sodium phosphate.12H 2 O to give final pH 5.5-6.0 Benzyldodecinium bromide 0.10 mg  0.10 mg  Polysorbate 80 0.2 mg 0.2 mg Water for injection q.s. ad. 1.0 mL 1.0 mL The active compounds, GELRITE™ gellan gum, phosphate buffer salts, benzyldodecinium bromide and Polysorbate 80 are added to and suspended or dissolved in water. The pH of the composition is adjusted to 5.5-6.0 and diluted to volume. The composition is rendered sterile by ionizing radiation. EXAMPLE 27 SOLUTION COMPOSITION I II 3,4-Dihydro-2-methy-4-(2- 2.0 mg 0.2 mg methyl)propylamino-2H-thieno- [3,2-e]-1,2-thiazine-6-sulfon- amide-1,1-dioxide hydrochloride (S)-(−)-1-( tert -butylamino)- 0.5 mg 0.5 mg 3-[(4-morpholino-1,2,5- thiadiazol-3-yl)oxy]-2- propanol maleate GELRITE ™ gellan gum 6.0 mg 6.0 mg Monobasic sodium phosphate.2H 2 O Quantity sufficient Dibasic sodium phosphate.12H 2 O to give final pH 5.5-6.0 Benzyldodecinium bromide 0.10 mg  0.10 mg  Polysorbate 80 0.2 mg 0.2 mg Water for injection q.s. ad. 1.0 mL 1.0 mL The active compounds, GELRITE™ gellan gum, phosphate buffer salts, benzyldodecinium bromide and Polysorbate 80 are added to and suspended or dissolved in water. The pH of the composition is adjusted to 5.5-6.0 and diluted to volume. The composition is rendered sterile by ionizing radiation. EXAMPLE 28 SOLUTION COMPOSITION I II R-(+)-3,4-Dihydro-4-ethyl- 2.0 mg 0.2 mg amino-2-methyl-2H-thieno- [3,2-e]-1,2-thiazine-6-sulfon- amide-1,1-dioxide hydrochloride (S)-(−)-1-( tert -butylamino)- 0.5 mg 0.5 mg 3-[(4-morpholino-1,2,5- thiadiazol-3-yl)oxy]-2- propanol maleate GELRITE ™ gellan gum 6.0 mg 6.0 mg Monobasic sodium phosphate.2H 2 O Quantity sufficient Dibasic sodium phosphate.12H 2 O to give final pH 5.5-6.0 Benzyldodecinium bromide 0.10 mg  0.10 mg  Polysorbate 80 0.2 mg 0.2 mg Water for injection q.s. ad. 1.0 mL 1.0 mL The active compounds, GELRITE™ gellan gum, phosphate buffer salts, benzyldodecinium bromide and Polysorbate 80 are added to and suspended or dissolved in water. The pH of the composition is adjusted to 5.5-6.0 and diluted to volume. The composition is rendered sterile by ionizing radiation. EXAMPLE 29 SOLUTION COMPOSITION I II R-(+)-3,4-Dihydro-4-ethyl- 2.0 mg 0.2 mg amino-2-(2-methoxy)ethyl-2H- thieno[3,2-e]-1,2-thiazine-6- sulfonamide 1,1-dioxide hydro- chloride (S)-(−)-1-( tert -butylamino)- 0.5 mg 0.5 mg 3-[(4-morpholino-1,2,5- thiadiazol-3-yl)oxy]-2- propanol maleate GELRITE ™ gellan gum 6.0 mg 6.0 mg Monobasic sodium phosphate.2H 2 O Quantity sufficient Dibasic sodium phosphate.12H 2 O to give final pH 5.5-6.0 Benzyldodecinium bromide 0.10 mg  0.10 mg  Polysorbate 80 0.2 mg 0.2 mg Water for injection q.s. ad. 1.0 mL 1.0 mL The active compounds, GELRITE™ gellan gum, phosphate buffer salts, benzyldodecinium bromide and Polysorbate 80 are added to and suspended or dissolved in water. The pH of the composition is adjusted to 5.5-6.0 and diluted to volume. The composition is rendered sterile by ionizing radiation. EXAMPLE 30 SOLUTION COMPOSITION I II R-(+)-3,4-Dihydro-2-(2-methoxy)- 2.0 mg 0.2 mg ethyl-4-propylamino-2H-thieno- [3,2-e]-1,2-thiazine-6-sulfon- amide 1,1-dioxide hydrochloride- (S)-(−)-1-( tert -butylamino)- 0.5 mg 0.5 mg 3-[(4-morpholino-1,2,5- thiadiazol-3-yl)oxy]-2- propanol maleate GELRITE ™ gellan gum 6.0 mg 6.0 mg Monobasic sodium phosphate.2H 2 O Quantity sufficient Dibasic sodium phosphate.12H 2 O to give final pH 5.5-6.0 Benzyldodecinium bromide 0.10 mg  0.10 mg  Polysorbate 80 0.2 mg 0.2 mg Water for injection q.s. ad. 1.0 mL 1.0 mL The active compounds, GELRITE™ gellan gum, phosphate buffer salts, benzyldodecinium bromide and Polysorbate 80 are added to and suspended or dissolved in water. The pH of the composition is adjusted to 5.5-6.0 and diluted to volume. The composition is rendered sterile by ionizing radiation. EXAMPLE 31 SOLUTION COMPOSITION I II III (S,S)-(−)-5,6-dihydro-4-ethyl- 22.26 g 22.26 g 1.113 g amino-6-propyl-4H-thieno- [2,3b]thiopyran-2-sulfonamide- 7,7-dioxide monohydrochloride (S)-(−)-1-( tert -butylamino)- 6.834 g 1.367 g 6.834 g 3-[(4-morpholino-1,2,5- thiadiazol-3-yl)oxy]-2- propanol maleate Sodium citrate.2H 2 O 2.940 g 2.940 g 2.940 g Benzalkonium Chloride 0.075 g 0.075 g 0.075 g Hydroxyethylcellulose  5.00 g  5.00 g  5.00 g Sodium hydroxide q.s. pH = 6.0 pH = 6.0 pH = 6.0 Mannitol 16.00 g 21.00 g 35.90 g Water for injection q.s. ad.  1000 g  1000 g  1000 g The active compounds, sodium citrate, benzalkonium chloride (in a 50% W/W solution), and mannitol are dissolved in approximately 400 mL water for injection in a tared and sterile vessel. The pH of the composition is adjusted to 6.0 by addition of 0.2 N sodium hydroxide solution, and water for injection is added until the weight of composition equals 750 g. The composition is sterilized by filtration, pushing the solution with a 2 bar pressure of 0.45 micron filtrated nitrogen. Then 250 g of a 2% hydroxyethylcellulose autoclaved solution is added and the obtained solution is homogenized by stirring with a magnetic stirring bar. The solution is aseptically subdivided into 3.5 mL aliquots and sealed. EXAMPLE 32 SOLUTION COMPOSITION I II (S,S)-(−)-5,6-dihydro-4-ethyl- 2.0 mg 0.2 mg amino-6-propyl-4H-thieno- [2,3b]thiopyran-2-sulfonamide- 7,7-dioxide monohydrochloride (S)-(−)-1-( tert -butylamino)- 0.5 mg 0.5 mg 3-[(4-morpholino-1,2,5- thiadiazol-3-yl)oxy]-2- propanol maleate GELRITE ™ gellan gum 6.0 mg 6.0 mg Monobasic sodium phosphate.2H 2 O Quantity sufficient Dibasic sodium phosphate.12H 2 O to give final pH 5.5-6.0 Benzyldodecinium bromide 0.10 mg  0.10 mg  Polysorbate 80 0.2 mg 0.2 mg Water for injection q.s. ad. 1.0 mL 1.0 mL The active compounds, GELRITE™ gellan gum, phosphate buffer salts, benzyldodecinium bromide and Polysorbate 80 are added to and suspended or dissolved in water. The pH of the composition is adjusted to 5.5-6.0 and diluted to volume. The composition is rendered sterile by ionizing radiation. EXAMPLE 33 Study of (S,S)-(−)-5,6-dihydro-4-ethylamino-6-methyl-4H-thieno[2,3b]thiopyran-2-sulfonamide-7,7-dioxide (I) in combination with Timolol Patients aged 40 or over, with either ocular hypertension or primary open angle glaucoma with an intraocular pressure (IOP) in one or both eyes of 22 mmHg or more at one time point each day while receiving timolol 0.5% twice a day (bid) alone were admitted to the study. Patients had been on timolol 0.5% bid, either alone or in combination for at least three weeks prior to study entry and had been on timolol 0.5% bid as their sole glaucoma therapy for at least two weeks prior to study admission. Secondary glaucoma was an exclusion as was a history of glaucoma surgery or laser trabeculoplasty/gonioplasty. Patients for whom timolol was contraindicated by the datasheet were excluded and also excluded were those on a concurrent β-blocker, carbonic anhydrase inhibitor, or clonidine. Thirty-one patients entered the study. Procedure 1. All patients had their visual fields plotted by Goldmann Perimetry prior to study entry. 2. Patients were admitted for a 12 hour diurnal curve (i.e., IOP recorded at 08.00, 09.00, 10.00, 12.00, 14.00, 16.00, 18.00, 20.00 hours approximately, the 08.00 recording was immediately prior to instillation of the drops). All pressures were measured by the same observer using the same Goldmann applanation tonometer. 3. Following recording of the baseline Diurnal Curve on timolol 0.5% bid, all of the patients were instructed to add 1 drop of a solution to each eye at 8:10 pm and 8:10 am, ten minutes after adding timolol, for seven days. The solution given to 16 of the patients contained 2% Compound I; the solution given to the other 15 patients was a placebo solution. 4. On Day 2, the IOP of each patient was measured at 8 am and 9 am, and a 12 hour diurnal curve was recorded on Day 8. preliminary IOP data follow: MEAN IOP PRESTUDY AND PERCENT CHANGE IN IOP ON DAY 8 FROM PRESTUDY TIMOLOL TIMOLOL PLUS TIME BASELINE COMPOUND I COMPOUND I PLUS TIMOLOL GROUP 8 am 27.4 −16.8% 9 am 27.1 −21.0% 10 am  25.4 −18.9% noon 25.6 −17.3% 2 pm 24.5 −18.6% 4 pm 25.2 −17.0% 6 pm 25.7 −18.2% 8 pm 24.4 −13.2% TIMOLOL TIMOLOL PLUS TIME BASELINE PLACEBO PLACEBO PLUS TIMOLOL GROUP 8 am 26.9 −3.4% 9 am 24.2 −4.5% 10 am  23.3 −1.7% noon 23.2 +0.2% 2 pm 21.6 +0.1% 4 pm 22.7 −0.1% 6 pm 23.1 −3.7% 8 pm 21.9 +6.6% These data are represented graphically in FIG. 1 . Overall, Compound I given every 12 hours demonstrated a clinically and statistically significant effect over the effect of timolol alone, ranging from 13%-21% based on worse eye analysis.

4y

BACKGROUND OF THE INVENTION The present invention relates to ultrasonic imaging. More particularly, it relates to an improved ultrasonic transducer for use in ultrasonic imaging systems. In the art relating to ultrasonic imaging, especially in the field of medical diagnostics through ultrasonic imaging, there have been provided, both hand-held and mechanically supported transducer assemblies. These assemblies are held in juxtaposition with the body of the individual undergoing examination. Included in such transducer assemblies, in a piezoelectric ultrasonic transducer which alternately transmits ultrasonic pulses into the body under examination and receives reflected pulse energy from tissue interfaces within that body. These reflected pulses are translated into electrical signals. The electrical signals may then be converted into a graphic representation of the tissue interfaces from which the reflected pulses were received, thus constituting a non-invasive examination or diagnostic tool. In such transducer assemblies, especially the hand held variety, the transducer per se has heretofore been in the form of a single unitary transducer. In one known example of such apparatus, the transducer itself has been approximately one-half inch across a major face thereof. It has been found that such dimension is quite large relative to the wave length of the ultrasonic pulses transmitted and received by the transducer. Accordingly, reflective ultrasonic pulses received by the transducer at one part of the transducer may be totally out of phase with the impulse received from the same spot on the target at another part of the same transducer. This, in turn, results in the signals received at one part of the transducer neutralizing or summing to zero with signals received at other parts of the transducer. The obvious result of such neutralization is a reduced signal strength of the detected reflections. SUMMARY OF THE INVENTION It is, accordingly, an object of the present invention to provide an improved ultrasonic transducer means. It is another object of the present invention to provide an ultrasonic transducer having improved signal response characteristic. In accomplishing these and other objects, there has been provided, in accordance with the present invention, an ultrasonic signal transducer characterized in that the piezoelectricly active element has a first unitary electrode over the entire surface of one face and a matrix of a plurality of individual electrodes on the opposite face. In the receive mode, such an arrangement effectively constitutes a plurality of individual transducers arranged in the matrix array while maintaning the efficacy of a unitary structure. The signals from the individual electrodes are individually amplified, full-wave rectified, and combined additively to produce a composite signal which eliminates the phase cancellation of the ultrasonic pulses distributed over the face of the transducer assembly. BRIEF DESCRIPTION OF THE DRAWINGS A better understanding of the present invention may be had from the following detailed description when read in the light of the accompanying drawings, in which: FIG. 1 is a pictorial representation of a hand held ultrasonic transducer assembly; FIG. 2 is a cross-sectional view of a portion of the operating end of the transducer assembly shown in FIG. 1; FIG. 3 is an enlarged fragmentary view of a transducer matrix constructed in accordance with the present invention; and FIG. 4 is a schematic representation of the transducer constructed in accordance with the present invention. DETAILED DESCRIPTION Referring now to the drawings in more detail, there is shown in FIG. 1 a representation of a hand held ultrasonic transducer structure 2. The structure 2 includes a main body portion 4 which terminates in an operating end 6 in the form of a truncated cone. At the opposite end of the body portion 4 from the operating end 6 there is an interconnecting cable structure whereby the transducer structure is electrically connected to suitable driving and analyzing apparatus. As shown in FIG. 1, when the transducer structure 2 is used as means for accomplishing non-invasive examination of internal tissue of a human body, the operating end 6 is positioned against that body 8 and arranged to occupy a field of view between adjacent ribs 10 toward internal tissue interfaces. In FIG. 2 there is shown, in a cross-sectional view, a representation of certain features of a preferred embodiment of an ultrasonic transducer structure constructed in accordance with the present invention. The body portion 4 of the transducer structure 2 houses a suitable transducer assembly 12 which is arranged to be mechanically oscillated through a predetermined angle about a pivot point 14. The driving mechanism for effecting oscillation of the transducer assembly 12 is not a part of the present invention and is, accordingly, not illustrated herein. The interior of the body portion 4 is filled with a suitable inert coupling fluid 16. The operating end 6 of the transducer structure body portion 4 is provided with an acoustically transparent window 18. The window 18 also serves to seal the operating end of the transducer head structure 2 in order to retain the fluid fill 16. Various features of a preferred embodiment of an ultrasonic system into which the structure of the present invention may be incorporated are shown in the following copending patent applications: Ballinger Ser. No. 173,859 filed July 30, 1980, now U.S. Pat. No. 4,300,217, relates to a Transducer Head Structure. Gessert Ser. No. 173,874 filed July 30, 1980 relates to a Real Time Fill Circuit. Evert Ser. No. 224,897 filed Jan. 14, 1981, now U.S. Pat. No. 4,316,271, relates to a Fluid Fill Purge Arrangement. Evert Ser. No. 224,899 filed Jan. 14, 1981 relates to an Angular Position Sensor and Helmstetter Ser. No. 242,967 filed Mar. 12, 1981 relates to a Signal Conditioning Circuit. While the aforementioned copending applications all relate to various features of an ultrasonic imaging system those features are not essential to the present invention. The disclosures in those applications might be helpful, however, in understanding the environment of present invention. As hereinbefore noted, included in the transducer assembly 12 is an ultrasonic transducer per se. In conventional arrangements used heretofore, the transducer per se has been, for example, on the order of a half inch across a major face thereof. That dimension is relatively large compared to the wavelength of the ultrasonic pulses transmitted and received by the transducer. As such, echo pulse signals received by different parts of the transducer from the same point in the body under examination will impinge upon the transducer in phase opposition relationship. That phase opposition relationship produces a neutralizing effect, or summing to zero, of the effective signals. This is especially observed in the case of the piezoelectric element having a single electrode on and substantially covering each of the two major opposite faces, since those electrodes can only sense the net effect distributed across the face of the piezoelectric element. In accordance with the present invention, and as shown in FIGS. 3 and 4, that difficulty is overcome by dividing the electrode on one face of the piezoelectric element into a matrix of a plurality of electrically independent electrodes distributed over the one major face of the piezoelectric element. Thus, as shown in FIGS. 3 and 4, a piezoelectric transducer element 20 has a unitary electrode 22 which extends over one major face of the piezoelectric element and is connected to an input pulse control circuit 23. On the opposite face of the piezoelectric element 20 from the unitary electrode 22 there is a two-dimensional matrix of a plurality of the aforementioned electrically independent electrode elements 24. Each of the electrode elements 24 is connected to a diode limiter 26, thence to ground. The elements 24 are also each connected to the input of a corresponding amplifier 28. The output of each of the amplifiers 28 is connected to a associated full-wave rectifier 30. The output of each of the full-wave rectifiers 30 is fed in common to the input of a summing circuit 32. The output of the summing circuit is, in turn, applied to the conventional signal conditioning circuitry for an imaging transducer system. While no specific number of independent electrodes appear to be critical, a 6×6 matrix has been found to be satisfactory. In the transmit mode, the common electrode 22 may be pulsed by the input pulse control circuit 23 to generate the series of ultrasonic pulses for transmission into the body under study. In the transmit mode, the electrically independent electrodes 24 are effectively grounded through the diode limiting circuits 26. In the received mode, the echo ultrasonic signals returned to the transducer impinge on certain parts of the transducer surface with a portion of the returned wave in phase opposition to the signals received on other portions of the transducer. With the electrically independent electrodes 24 actively detecting the signals, each of the electrodes 24 will respond to the pulse energy impressed on the transducer in the immediate vicinity defined by the individual electrode itself. Thus, the transducer responds to the ultrasonic wave as though the transducer was in fact a plurality of independent transducers. Thus, a negative pressure signal at one particular location on the surface of the transducer will be detected by the immediately adjacent independent electrode 24 while a positive pressure signal applied to the transducer at a different location thereon would be detected by the independent electrode 24 in that vicinity. The signals detected by the electrodes 24 are very low level signals. Accordingly, those signals are amplified by the respective amplifiers 28 to a level suitable for transmission to the full-wave rectifiers 30. When the signals from the individual electrodes 24 have been full-wave rectified by their associated rectifiers 30, the resultant signals will all be unidirectional. In this manner, all of the resulting pulse signals may be applied to the summing circuit 32 to be combined additively to produce a much higher level signal. Such higher level signal may then be applied to the conventional signal conditioning circuitry necessary to produce the desired imaging of the body under examination. In this manner, the neutralizing effect of ultrasonic pulses arriving at different parts of the transducer out of phase with each other has been eliminated. Thus, there has been provided, in accordance with the present invention, an improved ultrasonic transducer system including a phase insensitive ultrasonic transducer.

4y

BACKGROUND OF THE INVENTION In a dry room or car interior, it may require a humidifier for humidifying the air for comfortable living or driving. However, it is not available or it is difficult to obtain a portable mini humidifier from the commercial source. Even a prior art of U.S. Pat. No. 4,085,893 disclosed an ultrasonic humidifier for atomizing water or other liquid, which however has the following drawbacks: 1. A water supply system including conduit or tube must be provided for supplying the water to be atomized by an ultrasonic vibrator, thereby causing a complex structure and unsuitable for portable uses. 2. There is no sensor provided for sensing the humidity in the air. 3. There is also no indicator showing the water content in a water supply system. The present inventor has found the drawbacks of the prior art and invented the present portable humidifier. SUMMARY OF THE INVENTION The object of the present invention is to provide a portable humidifier comprising: a bottle for storing water therein, a capillary device immersed in the bottle for capillarily absorbing water as stored in the bottle, an ultrasonic vibrator mounted on an upper portion of the bottle for normally contacting a top wick portion of the capillary device and operatively vibrating for compressing the top wick portion for ejecting water mists upwardly outwardly through a plurality of perforations formed through the vibrator, a control device formed on a top cover of the bottle for controlling the on-off operation of the vibrator, a sensor formed on the top cover for sensing the surrounding humidity for reminding the user whether to actuate the control device for humidifying the surrounding, and a light indicator for illuminating and checking water stored in the bottle to remind whether to refill water into the bottle. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of the present invention. FIG. 2 is a sectional drawing of the present invention. FIG. 3 is an exploded view showing the elements of the present invention. FIG. 4 is a front-view illustration showing an inside wall of the sensor means having guiding ribs flared on the inside wall for homogeneously dispersing the water mists into the surrounding. FIG. 5 is a partial sectional drawing of the present invention showing the depression of the control means and opening of the sensor means for spreading water mists outwardly. FIG. 6 shows the closing of the sensor means and the restored control means for switching off the vibrator operation of the present invention. DETAILED DESCRIPTION As shown in the drawing figures, the present invention comprises: a housing 1 , a capillary means 2 , an ultrasonic vibrator 3 , a control means 4 adjacent to a rear side R of the housing 1 , a sensor means 5 adjacent to a front side F of the housing 1 , and a light indicator 6 . The housing 1 includes: a transparent bottle 11 , a bottom holder 10 embedded on a bottom portion of the bottle 11 , a covering plate 111 formed on an upper portion of the bottle 11 for closing the bottle 11 having an upper opening 112 formed through the covering plate 111 for refilling water into the bottle 11 and for inserting the capillary means 2 into the bottle 11 by passing through the opening 112 , a side socket 110 formed in the bottle 11 for resiliently providing a coupler 13 in the socket 110 for coupling an upper casing 12 detachably engaged on an upper portion of the bottle 11 , and a top cover 14 encapping the upper casing 12 . The capillary means 2 includes: a capillary tube 21 having its upper portion secured in the upper casing 12 of the housing 1 and protruding downwardly through a tube opening 121 formed through the upper casing 12 and through an upper opening 112 in the covering plate 111 to be inserted into the bottle 11 ; a wick member 22 longitudinally formed in the capillary tube 21 having a top wick portion 23 protruding upwardly from the capillary tube 21 to be contacted with the ultrasonic vibrator 3 ; a bottom plug 24 fixed on a bottom portion of the capillary tube 21 having a plurality of slots 241 formed in the plug 24 to be fluidically communicated with the wick member 22 disposed in the capillary tube 21 ; and a tension spring 25 retained in the lower portion of the capillary tube 21 and resiliently urging the wick member 22 upwardly to help a resilient contacting between the top wick portion 23 with the vibrator 3 . The capillary means 2 may be inclinedly secured in the housing 1 as shown in FIG. 2 to increase the length of capillary tube for absorbing much water therein. The wick member 22 may be further protected by a sleeve disposed around the wick member 22 which is made of water-absorbable material, such as cotton, foam, etc. The ultrasonic vibrator 3 includes: a piezoelectric actuator 31 secured in the upper casing 12 and electrically connected to the control means 4 ; and a perforated vibrating blade 32 having a plurality of perforations 33 formed through the blade 32 and secured to the piezoelectric actuator 31 , whereby upon switching-on of the control means 4 to actuate the piezoelectric actuator 31 , the vibrating blade 32 will be vibrated to compress the top wick portion 23 having water absorbed therein to eject water mists upwardly outwardly through the perforations 33 in the blade 32 to be spread into the environment through a front opening 141 formed in the top cover 14 . Each perforation 33 formed in the vibrating blade 32 may have a diameter of 6˜9 microns, but not limited in the present invention. The control means 4 includes: a button plate 41 pivotally secured in a rear portion of the top cover 14 by a pivot means 40 for normally shielding a rear opening 142 formed in the top cover 14 , a front tooth 42 formed on a front portion of the button plate 41 to be engaged with a pair of bifurcated teeth 511 formed in a rear portion of the sensor means 5 for opening the sensor means 5 , a switch button 43 resiliently formed on an electronic module 45 and having a button spring 44 disposed around the switch button 43 to normally urge a central bottom portion of the button plate 41 upwardly to be slightly separated from the switch button 43 ( FIGS. 2 and 6 ) to keep normal-open of the switch button 43 , and a power source adapter 46 adapted to be connected with an utility power supply and electrically connected to the electronic module 45 , with the electronic module 45 secured in a rear portion of the upper casing 12 . The button plate 41 includes a bottom protrusion 411 preferably formed as an arcuate shape as shown in FIG. 5 for smoothly depressing the switch button 43 of the control means 4 . The sensor means 5 includes: a sensor plate 51 pivotally secured in a rear portion of the top cover 14 by a pivot 50 formed on a rear portion of the sensor plate 51 for normally shielding a front opening 141 of the top cover 14 , a pair of bifurcated teeth 511 formed on a rearmost end portion of the sensor plate 51 to be engaged with the front tooth 42 of the button plate 41 of the control means 4 , a humidity indicator 52 secured in an indicator recess 512 formed in the sensor plate 51 for indicating the humidity as sensed from the surrounding through a vent 531 formed in a cover sheet 53 (with the cover sheet 53 covering the humidity indicator 52 on the sensor plate 51 ); with the sensor plate 51 corresponding to the vibrating blade 32 of the ultrasonic vibrator 3 adjacent to the front side F of the housing 1 ; whereby upon depression on the button plate 41 of the control means 4 , the front tooth 42 of the button plate 41 will downwardly bias the bifurcated teeth 511 to lift the sensor plate 51 from FIG. 6 to FIG. 5 to open the sensor plate 51 to allow the water mists as ejected by the ultrasonic vibrator 3 to be spread outwardly through the front opening 141 of the top cover 14 for humidifying the surrounding such as in a room or in a car. Simultaneously, the depression of the button plate 41 will downwardly depress the switch button 43 to actuate the ultrasonic vibrator 3 for ejecting the water mists upwardly. The humidity indicator 52 may be a color-change indicator including cobalt chloride which will be changed from red color to blue color, indicating the change from a wet condition (red) to a dry condition (blue). When it shows a blue color, it indicates the environment is dry and the present invention may be actuated to spread water mists into the air for obtaining a suitable humidity. The sensor plate 51 has its inside wall 54 formed with a plurality of guiding ribs 55 flared sidewardly from a longitudinal center of the inside wall 54 as shown in FIG. 4 for guiding the water mists as upwardly ejected from the ultrasonic vibrator 3 to be spread outwardly sidewardly for homogeneously dispersing the mists into the surrounding air for rapidly reaching a desired comfortable humidity. The light indicator 6 includes: at least a lamp 61 such as a light-emitting diode (LED) mounted in a lower portion of the upper casing 12 for projecting light downwardly through a prism lens 62 formed in the covering plate 111 of the bottle 11 for illuminating the water stored in the bottle 11 for checking the water level L whether to refill water into the bottle or not. The lamp 61 may be modified to be a plurality of LEDs with different colors and may be flashed as driven by a flashing circuit, not limited in the present invention. Upon decoupling of the upper casing 12 from the bottle 11 by depressing the coupler 13 inwardly, the upper casing 12 and the elements implemented therein will be removed and the water may be re-filled into the bottle through the opening 112 . When depressing the button plate 41 of the control means 4 for starting the ultrasonic vibrator 3 , the front tooth 42 , as engaged with the bifurcated teeth 511 of the sensor plate 51 , will be biased and lifted upwardly as shown in FIG. 5 , a rear tooth 511 r of the bifurcated teeth 511 will be frictionally engaged with the front tooth 42 to temporarily “lock” the front tooth 42 in position for continuously depressing the switch button 43 for actuating the vibrator 3 during the humidifying operation. When it is intended to stop the humidification, the sensor plate 51 is lowered to close the opening 141 and the bifurcated teeth 511 will spur the front tooth 42 of the button plate 41 upwardly (from FIG. 5 to FIG. 6 ) to restore the button plate 41 to allow the button spring 44 to resiliently urge the protrusion 411 of the button plate 41 upwardly to be separated from the switch button 43 , remaining a gap G between the button 43 and the button plate 41 and thereby deactivating the vibrator 3 to stop its vibrating operation. The present invention is superior to the prior art with the following advantages: 1. The humidifier is a compact portable unit, being easily carried and conveniently used in a tiny space. 2. A sensor is provided for checking when to start the ultrasonic vibrator for operating the humidifier in a more scientific way. 3. Light indicator (LED) is provided for always checking the water level (L) in the bottle and also for projecting color light into water for enriching beautiful ornamental effect. 4. Guide means is provided for guiding the water mists from the vibrator to be homogeneously spread outwardly to the air for a more uniform humidity within the room or in a car. The present invention may be modified without departing from the spirit and scope of the present invention. The housing may also be further added therein with air-refreshing agent, deodorant or other hygienic agents.

4y

CROSS REFERENCE TO RELATED APPLICATION This application is a divisional application of U.S. patent application Ser. No. 08/814,313, filed Mar. 10, 1997, now U.S. Pat. No. 5,974,706. BACKGROUND OF THE INVENTION The present invention relates to interchangeable tool attachments powered such as a bucket, a grapple, hydraulic hammer, tampers, augers and the like used with a power operated arm of an implement such as an excavator or backhoe. The tools use a common frame mounting for coupling to a quick attachment bracket as shown in the present invention. The tools also are made to receive a separate mounting plate for regular pin connection to the arm. Efforts have been made to provide couplings that can automatically connect tools to an articulated arm of an excavator, backhoe or the like, but most of these require operator action, as well as lacking reliability. Many of the present quick attachment brackets are complicated and time consuming in operation, requiring mechanically removing pins for connection as well as disconnection. One of the prior art couplings is illustrated in U.S. Pat. No. 5,110,254. Problems can persist with wear as the unit is used, in that there is no adequate compensation to take care of wear that occurs. SUMMARY OF THE INVENTION The present invention relates to a quick attachment bracket assembly for attaching various tools to an excavator, backhoe, or other powered implement that includes a power operated arm or boom. The specific embodiment shown is an excavator arm that has an actuator for pivoting a bucket or grapple around a horizontal axis, and also has actuators for manipulating the arm. In the present invention, a bucket or grapple has mounting walls on which a selected frame for either pin mounting or quick attach mounting can be fixed with no modification to the frames. In a preferred form of the present invention a quick attachment frame is on the tool and the frame couples to a quick attachment bracket mounted to the arm and connected to the operating linkage used for controlling the tool so that the quick attachment bracket can be pivoted about a horizontal axis under power. The quick attachment bracket carries a spring loaded latch member that is pivotally mounted on the bracket so it will pivot from a position wherein it will engage and hold a frame that is welded or pinned in place on a tool, such as a bucket or a grapple hook. The quick attachment bracket is made to slide into place on the frame on the tool. As the bracket slides into place under power operation of the mounting arm, the latch pivots against its spring load to accommodate the movement of the bracket relative to the frame. As the bracket seats in position on the frame, the latch snaps into place under the spring load to securely hold the frame on the bracket. The primary contact points for carrying loads from the tool (bucket or grapple) automatically adjusts for wear and manufacturing tolerances, so that the tool remains tight fitting on the bracket and will not excessively loosen as wear occurs. Additionally, the quick attachment bracket carries a pin that protrudes from side plates of the bracket. The frame on the tool has spaced side plates with hooks at the outer ends that straddle the side plates on the attachment bracket so the tool can be supported on the pin to permit ease of maneuverability of the bucket during the coupling and uncoupling operation. This permits the operator to move the tool after the bracket and frame are unlatched or uncoupled. The frame and tool will hang suspended from the bracket when the hooks are engaged with the pin, and the tool, such a bucket, can be placed with one side on the ground for the latching operation. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic side elevational view of a typical excavator arm end portion having a quick attachment bracket made according to the present invention installed thereon and shown adjacent a tool, comprising a bucket, for attachment; FIG. 2 is a perspective view of a bucket showing the bucket mounting frame in position on the back wall thereof; FIG. 3 is a first perspective view of the quick attachment bracket removed from the excavator arm showing the arm mounting side; FIG. 4 is a perspective view of the quick attachment bracket shown in FIG. 3 viewed from the side that faces the tool in mounting; FIG. 5 is a side elevation view showing the arm in another stage of attaching the bucket showing a rod on the bracket in position to support a bucket and to position it for attachment through a hook on the bucket frame; FIG. 6 is a view similar to FIG. 5 showing the arm and quick attachment bracket mating with a frame on the bucket; FIG. 7 is a view similar to FIG. 5 illustrating the quick attachment bracket in a latched position with the bucket frame; FIG. 8 is fragmentary sectional view taken on line 8--8 in FIG. 7, with the bucket walls removed for clarity; FIG. 9 is a fragmentary enlarged sectional view of the quick attachment bracket and tool frame shown in latched position; FIG. 10 is a perspective view of the latch used for holding the bucket frame in mounted position; FIG. 11 is an enlarged view with parts removed and broken away showing the quick attachment bracket in a first stage of unlatching from the bucket; FIG. 12 is a view showing the quick attachment bracket being rotated from the bucket, wherein the bucket can be supported on hooks and returned to be supported on the ground; FIG. 13 is a side elevational view of a bucket used with the present invention before a frame is attached, with parts in section and parts broken away; FIG. 14 is a rear view of the bucket of FIG. 13; FIG. 15 is a perspective view of a bucket utilizing a common mounting plate but for a pin mounting assembly; and FIG. 16 is side view of a grapple utilizing a frame that can be coupled to the quick attachment bracket of the present invention with parts in section and parts broken away. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A powered implement, such as an excavator or backhoe 10 is shown only as block since such implements are well known. The implement has an arm illustrated fragmentarily at 16. The arm 16 is pivotally mounted to a base arm section and the base arm is pivoted to the implement 10. The arm 16 is controlled and operated from the implement 10 mounting platform, using hydraulic actuators from a source of hydraulic fluid under pressure, operated through controls, such as valves 14. An end portion of the arm 16 includes a link assembly 18 that is used for controlling a pivoting tool, such as bucket 20. The link is actuated with a double acting hydraulic actuator shown only schematically at 22 and operated through controls 14. The actuator 22 extends and retracts an actuator rod 22A under power and controls a tool, as shown by controlling pivotal movement of a quick attachment mounting bracket 24 that is pivotally mounted on a pin 26 to the outer end of the arm 16. The actuator, acting through linkage 18 will control then pivoting of the bracket about the horizontal axis of the pin 26. The link assembly 18 as shown, has a pair of links 19A and 19B that are pivotally mounted together with a pin 19C. The pin 19C also is the attachment pin for the actuator rod, 22A. The links 19A and 19B are suitably bifurcated to have multiple attachments on the single pin. The link 19A is pivotally mounted to the boom or arm 16 at the pin 19D and the outer end of link 19B is pivotally mounted to quick attachment bracket 24 with a pin 28. The quick attachment bracket 24 is shown in FIGS. 3 and 4 individually and also in FIG. 1 when installed on arm 16. The quick attachment bracket 24 has a pair of side plates 30, 30 that form a support for a nose piece wrapper or end portion 32 that extends across the space between the side plates 30 and is welded to the side plates 30 to form an assembly. The side plates 30 are formed to have lower support ears 36 that are recessed to support a channel shaped saddle or retainer channel 40 that is a cross member extending across the space between the side plates 30 and is welded thereto to secure the opposite end of the quick attachment bracket 24. The side plates 30 receive the main mounting pin 26 through bores 26A and the pin 26 extends across the space between the side plates 30. The linkage pin 28 also extends through bores 28A and extends across the space between the side plates 30. A pin 38 is supported on the outer ends of the ears 36 and is held in place partially under a lead-in lip 40A on one outer edge of the channel shaped saddle 40. The pin 38 extends outwardly beyond the side plates 30 to provided support ends 38A, which are used to support the tool or bucket 20 during mounting and releasing the bucket 20 from the quick attachment bracket 24. The pivot pin 28 also mounts a frame latch 41 shown in perspective view in FIG. 10 detached from the bracket 24, and also shown in FIGS. 1, 6,9 and others. The latch 41 is a yoke shaped member that has a pair of latch arms 42 held together with a latch bar 43 at their outer ends. The arms 42 have hubs 44, 44 that also are shown in FIG. 10. The hubs 44 have bores that pivotally mount over the shaft 28 and grease fitting bores are shown in FIG. 10 for lubrication for ease of pivoting. The hubs 44 have control arms 45, extending therefrom and the arms 45 are spring loaded with strong compression springs 46 that are retained in spring supports 47 that are fixed to the side plates 30 and bear against the arms 45. Roll pins 45A are provided on the control arms 45 to retain the springs 46 in place. The end 43A of the latch 41 is rounded with a large radius for smooth engagement when latching. The latch 41 is thus urged by the springs 46 to rotate in counterclockwise direction as shown in FIG. 1, and are retained from rotating too far by suitable stops that will be explained. The bucket 20 has a quick attachment frame 48 attached thereto. The quick attachment frame 48 is shown in FIG. 2 in perspective view and in enlarged cross sectional view in FIGS. 9 and 11. The frame 48 is made up of side plates 50, 50 that are welded to a latch backing plate 52. The side plates 50 have hook ends 54 with receptacles 56 formed in them (see FIGS. 5 and 6). The side plates 50 of the frame 48 are spaced wider than the side plates 30 and wider than the nose piece 32 and the saddle 40 and will fit over the outside of the quick attachment bracket 24 when the bracket seats in the frame 48. The frame 48 also seats between the side plates 20A and 20B of the bucket 20. The frame 48 is welded to a back base wall 21 of the bucket 20, which is formed separately and becomes an integral part of the frame 48, as will be explained. The latch 41 is held in its "ready" position shown in FIG. 1 when the bracket is ready to be used in any selected way, and as shown a pivoting pawl 58 is mounted on a shaft 57, on at least one side of the latch aligns with a hub of the latch and as shown in FIG. 6, it is positioned to engage a stop lug 59 integral with a hub 44 aligning with the pawl 58. The stop lug has a stop surface 59A for holding the latch retracted for a release position and has a second surface 59B which is used to hold the latch in the ready position as shown in FIG. 1. The pawl is spring loaded with a torsion spring 58A to rotate in clockwise direction as shown in FIG. 6. The torsion spring 58A is shown only schematically. Thus the end of the latch protrudes into the area overlying the channel 40 when it is in its ready position. The plate 52 of the frame 48 is formed to provide support for the quick attachment bracket 24 and as perhaps best understood from the showing in FIG. 6, includes a planar flange portion 52A at one end, near the bottom of the bucket 20 when the bucket is working. In the mid portions of the plate 52 the plate bends inwardly through an opening 21C in the rear wall 21 of the bucket 20, and then an inclined latch wall section 52B is formed to extend back outwardly. The plate has a section 52F that is coplanar with flange 52A and the end of the plate 52 then has a rim flange 52C formed at right angles to the plane of the planar flange 52A and the wall section 52F, which plane is illustrated at 52D in FIGS. 5 and 6. The rim flange 52C forms a rim which is seated in a receptacle formed in the ears 54 of the side plates 50 of the frame 48. The wall 21 of the bucket 20 at the rear of the open side is formed with an inverted channel edge portion 21D, as perhaps can be seen by referring to FIGS. 13 and 14 as well as FIGS. 9 and 11. The wall 21 edge portion 21D near is the open end of the bucket 20 is formed as a channel with a channel a base wall 21A and a flange 21B that is formed back toward the opposite end of the wall 21. An opening 21C is formed in the wall 21 to receive the formed plate 52 of the frame 48, and edge portions of the side plates 50 that extend out from the plate 52 to provide a welding surface. A liner wall panel 62 is used on the interior side of the wall 21 and tapers away from wall 21 in direction toward the open end of the bucket. The liner wall 62 has a flange 62A that is welded back to the wall 21 to enclose or cover the opening 21C from the inside. The liner wall 62 is also welded to the side walls of the bucket when the walls 21 and 62 are installed on a bucket. The wall edge portion 21D is carefully formed since it is used in the mount of the frame on the bracket 24. The bend where the flange 62A joins the main portion of the liner wall 62 is welded to the edge of flange 21B of the wall 21, so the plane of the face 65 of the flange 21B relative to the plane of the wall 21, and the plane of the plate 52 can be closely controlled. The wall assembly 67 of the wall 21 and liner wall 62 is used for a number of tools so the frame 48 is easily mounted. As may be seen in FIG. 9, when the frame 48 is welded to the back or base wall 21, the rim flange 52C is mounted against the wall portion 21A and the wall 52 is placed so flange 52A and the wall section 52F are also tightly against the wall 21. The distance from the plane 52D and the plane of surface 65 is closely controlled. The first step for mounting the tool, as shown the bucket 20, is shown in FIG. 1. The bucket is considered as having been set on the ground in the position shown, with the frame 48 at the top. The excavator arm 16 is moved so that the quick attachment bracket 24 is adjacent the bucket 20. The bracket 24 is tilted so that the channel 40 is facing generally toward the frame 48, with the rod 38 above the ears 54 of the frame. In FIG. 5 in the sequence of attaching the frame 48 and the bucket 20 to the quick attachment bracket 24, it can be seen that the arm 16 has been moved to a position where the pin 38 rests in the receptacles 56 of the frame 48 on the bucket 20. Again, the hooks 54 on the side plates 50 of the frame fit to the outside of the quick attachment bracket side plates 30. The arm 16 can now be lifted and the bucket 20 will hang from the quick attachment bracket 24, so it can be moved or positioned where desired for finishing the attachment coupling. The suspension of the bucket on rod 38 through hook end 54 and receptacles 56 position the bucket and frame 48 properly for automatic attachment. This also illustrates that when uncoupling the bucket, the bracket 24 can be released from the frame 48 and the bucket will not fall to the ground, but rather will be supported on the rod 38 and the hooks 54 which have receptacles 56 for the rod 38. The rod 22A of the hydraulic cylinder or actuator 22 is extended so that the linkage 18 tilts the quick attachment bracket 24 to a position where the plate portion 32A of the wrapper nose 32 rests on the flange 52A of plate 52 of the frame 48, as shown in FIG. 6. The open end of the channel 40 is aligned with the flange 52C and the end of the wall of the 21, including the end wall 21A and the flange 21B, which are removed from FIG. 6 for clarity. As the bracket 24 is moved to the position shown in FIG. 6 the latch 41, which was protruding from the frame and held there by pawl 58 is forced to the position shown in FIG. 6, to ride on plate portion 52F against the action of springs 46, which urge the latch in counterclockwise direction. The bucket has to resist the force of the springs 46 as the bracket is slid to the position of FIG. 6. The pawl 58 is spring loaded in clockwise direction, as seen FIG. 6, with a torsion spring 58A that has a leg that fits under the pawl end and when the latch is moved by the frame plate 52 as the bracket is slid into place the pawl moves away from the stop surface 59B and will rest against the lug 59 on the latch. The next step in attaching or mounting the bucket on the quick attachment bracket 24 is to move the bracket in direction indicated by the arrow 70 in FIG. 6, to slide the bracket so the nose piece 32 slides linearly under a retaining bar or cross member 72 that is mounted on and extends between the side plates 50 of the frame 48 to form a retainer receptacle. The retaining bar 72 holds the nose piece 32 against the flange 52A of the plate 52, and the latch 41 moves so the latch end 43A, which is rounded with a large radius, engages the surface of inclined latch section 52B to prevent the bracket 24 from reversing relative movement with respect to the frame 48 and uncoupling. The frame 48 and attached tool, as shown, the bucket 20, are ready for use. FIG. 8 is a sectional view take on an irregular sight line to illustrate the frame 48 and latch 41 in latched position with parts removed for clarity. The bucket sides are not shown, but an end view of the flange 21B against the outer leg 40B of the channel shaped saddle 40 is shown. FIG. 9 is an enlarged sectional view of the bracket 24 and frame 48 in fully engaged or mounted position. The main panel 32A of nose piece 32 is held against frame flange 52A and is held from moving away from the frame 48 and frame plate 52. The nose piece 32 is free to slide away from the retainer bar 72 but is retained in position by the latch 41 acting against the tapered wall section 52B of the frame plate 52. The channel shaped saddle 40 is made so that it will accommodate wear in combination with the frame and the edge portion 21D of wall 21 formed by walls 21A and 21B. The channel shaped saddle 40 includes a first leg 40B that supports the lip 40A, and this wall 40B is parallel to the plane 52D of the plate 52. It is also parallel to the wall or flange 21B of the bucket back wall top edge portion 21D. The channel shaped saddle 40 has a base 40C that is parallel to and spaced slightly from the rim flange 52C of the plate 52. The saddle further has an inclined formed corner wall section 40D that extends at an angle to the base 40C and which joins the side wall 40E. The inner surface 40F of the inclined corner wall section 40D acts as a cam surface against the corner of the frame plate rim formed between plate wall section 52F and the plate rim flange 52C. The cam surface 40F and the corner engage at a tangent point indicated at 76 in FIG. 9. The forces from the latch 41 and the seating forces developed when the bracket 24 is pushed into latched position in turn cause the cam surface 40F to force the wall 21B against the inner surface of the saddle wall 40B, along line 78 (FIG. 9) to eliminate play or movement when held with the latch 41. The tightening action will continue as the corner wears because of the cam surface 40F, so the latch bracket 24 and frame 48 will not loosen excessively. Also, the cam action insures tight seating of the parts even with manufacturing variations. FIG. 11 shows a first stage in the unlatching of the frame 48 and bracket 24. The latch 41 is moved to a position to clear the surface of plate section 52B, The latch 41 is rotated against the force of springs 46 either by mechanically prying the latch clockwise with a pry bar used in a receptacle 80 (see FIG. 10) acting through a slot 81 in the bracket side plate 30 (see FIG. 4) or by operating small hydraulic cylinders 84 having rods 85 that are mounted on brackets 86 bolted or otherwise fixed to the sidewalls 30 of the quick attachment bracket 24. The rods 85 of the cylinders are positioned to act on the respective lugs 45,and are single acting cylinders that are operated with a valve 83 (see FIG. 11). When the pistons 85 are extended, as shown in FIG. 11, the latch 41 is pivoted clockwise to a position where the latch end clears the surface of plate section 52B and the pawl 58 will snap under its torsion spring load to engage the stop surface 59A to hold the latch in its disengaged position. The arm 16 can then be actuated to back the bracket out from under the bar 72 so the frame and bucket can roll out of the bracket. The hooks 54 are positioned so that if the removal action is done with the bucket off the ground, the bucket will not fall free, but the hooks 54 and receptacles 56 will catch the ends 38A of rod 38 to hold the bucket, as shown in FIG. 12. The excavator can then be operated to deliver the bucket to a storage location and when the bucket is supported on the ground or other support, it can be released by manipulating the arm 16 or the bracket 24 by operating the actuator 22. The reset of the pawl 58 to hold the latch 41 in its ready position for reattaching the frame 48 is automatically done when the bracket is rotated to the position shown in FIG. 12. One of the sides of the link 19B has an actuator button 58C that is a protrusion which strikes the pawl 58 when the bracket 24 is rolled to its position shown in FIG. 12 as the bracket is removed from the frame 48. When the pawl 58 is slid off the surface 59A, the springs 46 kick the latch counterclockwise and the pawl spring 58A keeps the pawl against the stop lug 59 so the pawl end engages the surface 59B and holds the latch in position shown in FIG. 1. The protrusion or button 58C on the link 19B can be seen in FIGS. 1 and 9 as well. The hydraulic cylinder 84 can act as a stop for the latch 41 to hold it in its ready position, if a hydraulic release cylinder is used on the bracket 24. The bucket construction shown in FIGS. 13 and 14 for the frame 48 for the quick attachment bracket also is usable when a pinned bucket is desired. the pinned bucket is one where it is pivoted directly to the end of arm 16 and also directly to the end of link 19B. As shown in FIG. 15, a pinned bracket 88 comprises a flat plate 90 that fits against the outer surface of wall 21, and which covers the opening 21C and is welded in place. The plate 90 has a bent over end that fits around the end wall 21A for positioning. The plate carries pin brackets 92 that have bores for receiving pins to directly mount the bucket to the arm 16 and link 19B. FIG. 16 shows a grapple 100 that has three spaced grapple teeth 102 (two are shown where the closest one is broken away). The teeth 102 are mounted on the same wall assembly as used with the bucket, including on wall 21 that has an end wall 21A and a flange 21B for mounting the plate 52 and bracket 48. The wall 21 includes the opening 21C to receive the formed plate 52. The wall 62 and flange 62A are also used. The frame 48 can be welded in place on the grapple and then attached to the bracket 24, as shown in the previous figures. Grapples are used with "thumbs" or other reaction members against which the grapple will clamp loads, and the quick attachment bracket and frame permits changing the grapple to a different style without unpinning the thumb or reaction member. This greatly simplifies changing the grapples. It should be noted that the frame 48 is used on buckets of all sizes, and wider buckets are accommodated easily, without altering the frame. Fast reliable operation for interchanging buckets or other tool is achieved. The ability to remove the bucket with the bucket off the ground without having the bucket fall freely is helpful, and is achieved by use of the overlapping ears and receptacles on the frame 48, in combination with the rod 38. Any wear between the plate 52 and the channel saddle 34 will occur on the corner of the plate 52. The line of contact between the end of latch 41 and the tapered surface of the plate 52 will move up the surface on wall portion 52B and continue to latch the unit tightly in place. The latch 41 is spring loaded in counter clockwise direction. Normal manufacturing tolerances are also accommodated. The assembly 67 of the wall 21 and liner wall 62 can also be applied to tools for mounting the frame 48 on the tool for use with quick attachment bracket. Power augers and concrete breakers can thus be attached and removed easily. Although the present invention has been described with reference to preferred embodiments, workers skilled in the art will recognize that changes may be made in form and detail without departing from the spirit and scope of the invention.

4y

RELATED APPLICATIONS Filed on even date with this application are two U.S. patent applications of related subject matter. One is entitled “Online Modifications of Relations in Multidimensional Processing” U.S. application Ser. No. 09/475,786 entitled “Online Syntheses Programming Technique” U.S. application Ser. No. 09/475,436. The entire teachings of the foregoing applications are incorporated herein by reference. BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates in general to data management systems performed by computers, and in particular, to the processing of heterogeneous relations in systems that support multidimensional data processing. 2. Description of Related Art Multidimensional data processing or the OLAP category of software tools is used to identify tools that provide users with multidimensional conceptual view of data, operations on dimensions, aggregation, intuitive data manipulation and reporting. The term OLAP (Online analytic processing) was coined by Codd et al in 1993 (see Codd, E. F. et al., “Providing OLAP to User-Analysts: An IT Mandate”, E.F. Codd Associates, 1993). The paper by Codd et al also defines the OLAP category further. An overview of OLAP and other data warehousing technologies and terms is contained in Singh, H. S., “Data Warehousing. Concepts, Technologies, Implementations, and Management,” Prentice Hall PTR, 1998. The text by Ramakrishnan et al. in Ramakrishnan, R. and Gehrke, J., “Database Management Systems”, second edition, McGraw-Hill, 1999, describes basic multidimensional—and relational database techniques, many of which are referred to herein. OLAP systems are sometimes implemented by moving data into specialized databases, which are optimized for providing OLAP functionality. In many cases, the receiving data storage is multidimensional in design. Another approach is to directly query data in relational databases in order to facilitate OLAP. U.S. Pat. No. 5,926,818 by Malloy and U.S. Pat. No. 5,905,985 by Malloy et al describe techniques for combining the two approaches. The relational model is described in Codd, E. F., “A Relational Model of Data for Large Shared Data Banks, Communications of the ACM 13( 6):377-387 (1970). OLAP systems are used to define multidimensional cubes, each with several dimensions, i.e., hypercubes, and should support operations on the hypercubes. The operations include for example: slicing, grouping of values, drill-down, roll-up and the viewing of different hyperplanes or even projections in the cube. The research report by Agrawal et al (Agrawal et al., “Modeling Multidimensional Databases,” Research Report, IBM Almaden Research Center) describes algebraic operations useful in a hypercube based data model for multidimensional databases. Aggregate-type operations are described in several U.S. patents by Agrawal et al. and Gray et al. (i.e., U.S. Pat. Nos. 5,832,475; 5,890,151; 5,799,300; 5,926,820 by Agrawal et al. and U.S. Pat. No. 5,822,751 by Gray et al. SUMMARY OF THE INVENTION Measurements from various institutions and research entities are by nature heterogeneous. Synthesizing measurements into longer strings of information is a complex process requiring nonstandard operations. This is especially true when dealing with measurements lacking the accountant type structure of business related data. As, for example, health related information about individuals, genotype readings, genealogy records and environmental readings. The shortcomings of current OLAP tools in dealing with these types of non-associative measurements is evident, for example, by realizing the emphasis placed on aggregation operators such as max, min, average and sum in current tools and research. Most often, these operators are rendered useless by the lack of a quantifying domain such as “money”. On the other hand, when carefully synthesized and analyzed, these and other similar sets of measurements do contain valuable knowledge that may be brought to light using multidimensional analysis. In order to overcome some of the limitation in the prior art, the present invention discloses methods and embodiments supporting multidimensional analysis in data management systems. An object of the present invention is to enable online tuning of relations in multidimensional analysis. According to the invention, relations are modified by a depth-of-field operator that can be applied to any collection of dimensions and relations supported by the dimensions. In effect, the online depth-of-field operator varies the density of points or facts in a representation of a multidimensional cube. It allows one to experiment online with the definition of relations, thereby controlling the output of the synthesizing process. It is also an object of the present invention to facilitate online definitions of multidimensional cubes fit for being populated with data from various measurements and other cubes. According to the invention an axes matrix is used to specify axes structures related to each dimension or domain. An operator, called blowup operator herein, possibly associated with the axes matrix is implemented. These techniques create a connection between measurements and domains? and a user defined multidimensional view containing knowledge that is acquired through complex multidimensional processing. It is another object of the present invention to implement a syntheses process for multidimensional analysis. The process dynamically eliminates ambiguities, observed in combined measurements used to populate a hypercube. This is achieved by introducing additional relations reflecting dependencies between dimensions in the hypercube and by confirming combined measurements against selected realistic observations. It is yet another object of the present invention to implement a system that enables OLAP for a wider variety of data and structures than current relational implementation schemas, such as the star or snowflake schema and related techniques. In some cases, this is done by forcing the structures into current schemas, but in other cases, new and more dynamic schemas are introduced. Among the structures is a grouping operator for multidimensional analysis, applicable, among other things, to measurements about domains with variable level of granularity. The operator does not force the measurements into using the same level of granularity or hierarchy and it is generic with respect to any domain and hierarchical structure. The main processes introduced are reversible and therefore may be made to be well-behaved with respect to adding, updating or deleting measurements from the original system of relations. Thus, the processes, when combined, define a continuously updateable/editable OLAP system for heterogeneous relations. The heterogeneous relations and dimension structures may include, but are by no way limited to, measurements relating to health data for individuals (e.g., biomarkers), ecological data, genotype readings (e.g., location of markers in individuals), genealogical records, geographical data and so on. BRIEF DESCRIPTION OF THE DRAWINGS The foregoing and other objects, features and advantages of the invention will be apparent from the following more particular description of preferred embodiments of the invention, as illustrated in the accompanying drawings in which like reference characters refer to the same parts throughout the different views. The drawings are not necessarily to scale, emphasis instead being placed upon illustrating the principles of the invention. FIG. 1 is a block diagram illustrating an exemplary hardware setup required to implement the preferred embodiment of the present invention. FIG. 2 is a high level illustration of a join process associated with multidimensional analysis. FIG. 3 shows an exemplification of domains. FIG. 4 shows an exemplification of hierarchies and their level sets. FIG. 5 is a block diagram describing an online depth-of-field operator for multidimensional analysis according to the present invention. FIG. 6 is a block diagram describing an online blowup operator for multidimensional analysis according to the present invention. FIG. 7 is a block diagram describing an online syntheses programming technique for multidimensional analysis according to the present invention. FIG. 8 is an illustration of processes used to record composed measurements. FIG. 9 is a high level illustration of a grouping technique that allows measurements to be supported on different and varying levels according to the present invention. FIG. 10 is an illustration of a process used to convert hierarchies to dimension tables according to the present invention. FIG. 11 shows an exemplification of a fact dimension according to the present invention. FIG. 12 is an illustration of the definitions needed to generate a hypercube from measurements according to the present invention. DETAILED DESCRIPTION OF THE INVENTION The following description of the preferred embodiment is to be understood as only one of many possible embodiments allowed by the scope of the present invention. Reference is made to the accompanying figures, which form a part hereof. Overview Data from multiple sources has to be preprocessed before being fit for multidimensional analysis in a hypercube. This preprocessing is time-consuming, and to a great extend performed manually by ad-hoc programming or by the use of various tools designed specifically for each increment of the data warehousing process. More importantly, this preprocessing may need to be repeated every time a new knowledge is sought to be extracted from the data. The work may include adjusting the level of granularity of the data so that smaller strings of data, i.e., measurements, can be synthesized into larger pieces of information. The data strings have to be mapped onto dimensions and the mapping and the dimension structures depend on what type of knowledge is being sought from the data. To complicate things further, the dimensions are not necessarily independent variables and that leads to ambiguity, which needs to be resolved. Current techniques tend to be optimized to handle simple data, such as sales information by location, time, buyer, product and price. For this type of data, the level of granularity can be set universally, ambiguity is minimal and hierarchies are regular. In addition, for this type of data, the most useful aggregation operators are average, summation, maximums and minimum calculations. On the other hand, more complex data may require set operations like kinship measures and other non-binary or non-associative operators. The current invention reveals processes that transform a set of heterogeneous measurements, i.e., relations, into multidimensional data cubes, i.e., hypercubes. The original heterogeneous measurements are used to populate the cubes directly. The cubes support complex dimension structures, ambiguity resolution, complex operations between level sets and hierarchies that are not necessary regular or of aggregation type. Furthermore, the methods are entirely generic and therefore applicable to any data warehouse design. When combined and stored as definitions in additional metadata structures, e.g., the axes matrices of the present invention, the methods facilitate the automation of the processes required to build a data warehouse. Hardware FIG. 1 is a block diagram illustrating an exemplary hardware setup required to implement the preferred embodiment of the present invention. A client/server architecture is illustrated comprising a database server 101 and an OLAP server 102 coupled to an OLAP client 103 . In the exemplary hardware setup shown, the database server 101 , the OLAP server 102 and the OLAP client 103 may each include, inter alia, a processor, memory, keyboard, pointing device, display and a data storage device. The computers may be networked together through a networking architecture 104 that may be a local network connecting the hardware 101 , 102 and 103 . The network may also connect to other systems 105 . The OLAP client 103 , the database server 101 and the OLAP server 102 may all or some be located on remote networks connected together by a complex network architecture 104 that may include utilizing many different networking protocols. Those skilled in the art will also recognize that the present invention may be implemented combining some of the systems on a single computer, rather than the multiple computers networked together as shown. Those skilled in the art will further recognize that the present invention may be implemented using hardware where the database server 101 and/or the OLAP server 102 are distributed over several computers networked together. In the exemplary illustration the database 101 , the OLAP server 102 , and the OLAP client (or clients) 103 are grouped together as being the primary systems 100 for performing multidimensional analysis according to the present invention. Other systems ( 105 ), may however feed the combined system 100 with new data and information, through the network 104 , that subsequently may become part of the multidimensional analysis. Typically, the present invention is implemented using one or more computers that operate under control from operating systems such as Windows or UNIX type systems, etc. The operating systems enable the computers to perform the required functions as described herein. The database server 101 may support complex relational or multidimensional database designs or both but also a simpler system of flat files will suffice. The methods described in the present invention may be stored in the form of executable program code, in various formats. The program/machine code may be stored in the different systems shown in 100 both in memory and on storage devices. This may include low-level machine-readable code, high-level SQL statements, code executable in the database system and other program code executable within the various systems or subsystems in 100 . The code may be generated using various programming environments, including many C++ packages and the various languages specifically designed for accessing databases. The present invention may thus be considered a software article, which may be distributed and accessed using the various media or communication devices compatible with the operating systems used. Multidimensional Analysis FIG. 2 is a high level illustration of a join process associated with multidimensional analysis. It introduces the logical or conceptual view ( 200 ) of measurements, dimensions and compositions of measurements that is used throughout the present specification. The illustration is achieved by exemplifying the concepts. FIG. 2 shows four measurements numbered ( 202 ) by 1 , 2 , 3 and 4 and identified respectively as 203 , 204 , 205 and 206 . A measurement is a collection of related attributes/values from a stored or derived relation. Measurement 203 is from a relation on dimensions numbered by 1 , 2 and 3 in the sequence of dimensions 201 , it is therefore an element from a ternary relation with its first element (sometimes called attribute) “a” from dimension 1 , second element “b” from dimensions 2 and third element “c” from dimension number 3 . The measurement is said, here, to be about any of the dimensions or domains that support the measurement, e.g., 203 is a measurement about dimension (or domain) 1 , 2 or 3 and it is supported by the collection of dimensions (or domains) 1 , 2 and 3 . The measurement may be stored as a row in a relational database system ( 101 ), i.e., in a table with three columns, each representing one of the domains 1 , 2 and 3 , as is well known in the prior art. It may also be stored as a sequence of, possibly indirect, references to the attributes “a”, “b” and “c” in other structures either in a relational or multidimensional database or in files in 101 . It may also only exist in memory ( 100 ), even temporarily, or be the result of calculations or other processes that define relations, including derived relations obtained by copying or manipulating existing relations. Similar descriptions apply to the other measurements 204 , 205 and 206 . Measurement 204 is from a ternary relation on dimensions 2 , 3 and 4 as shown, measurement 205 is from a binary relation on dimensions 4 and 5 , etc. The measurements 203 , 204 , 205 and 206 , as shown, are selected such that they agree on overlapping dimensions and can therefore be joined, using the natural join, to form a larger composed measurement 207 . The composed measurement 207 is referred to, here, as a point in a multidimensional cube, i.e., a hypercube, with dimensions numbered by the sequence 201 . This default criterion, i.e., that the values agree and that the natural join is used, may be replaced for specific dimensions with other criteria. Thereby, allowing measurements to be composed or joined differently using operators (called join operators here) that specify the corresponding dimension values for the composed measurements. The default (natural) join process shown above and demonstrated on FIG. 2, uses a join criterion requiring matching values, for the same dimensions, and the join operator simply copies the values from the original measurements to the composed measurement. Well known operators such as sum, max, min or even averaging and many others may also be used as join operators. This may require that dimensions have a variant number of values associated with it, i.e., that the active domain changes online. As an example illustrating this a join criterion for a dimension containing values from a “money” domain may be to require that the attributes from different measurements about the dimension are numeric. The summation operator may then be used in the join process to assign an attribute from the “money” dimension to the composed measurement. Which join criterion and join operator is associated with each dimension may be controlled and defined by the user of the system performing the analysis. It may also be determined by the system using default behavior associated with domains or determined by available metadata. In order to define consistent results, independent of the order of compositions, for a sequence of joins performed using a join criterion; the join criterion may be required to define a mathematical equivalence binary (self-) relation on the dimension. In other words, be reflexive, symmetrical, and transitive. A binary relation over the dimension may be stored in system 100 , for example, as a table with two columns, each containing values from the dimension. Checking and enforcing any of the three conditions when storing or using a relation over the dimension can be implemented by simple algorithms and methods. Reflexivity may be enforced for a binary relation by checking for equality of the attributes forming a pair when evaluating if the pair is in the binary relation required to be reflexive. Symmetry may be enforced for a binary relation by only requiring a pair or its reflection to be actually stored in the table in order to be considered a part of the symmetrical relation. Transitivity may be enforced by similar methods: E.g., when a row is added, representing a new pair in the binary relation, to the table holding the binary relation, the system may also add, recursively, all other pairs (rows) needed to maintain transitivity. Equivalence binary relations may be defined by the user of the system or be predefined and may be stored along with other definitions in system 100 as described above. As relations are selected for multidimensional processing in a hypercube, each of the domains supporting the relations is associated with a dimension in the hypercube. Relations containing measurements about a common domain may be made to share the same dimension in the hypercube or the domain may be mapped to different dimensions in the hypercube for some of the relations. This mapping of domains to dimensions, and the naming of dimensions, is controlled by the user of the system performing the multidimensional processing or OLAP. The mapping may also be controlled fully or partly by the system using available metadata and default system behavior to determine the mapping and naming of dimensions. An example described in connection with FIG. 7 below illustrates this by mapping an “Age” domain in two relations, called Diagnosis and Whereabouts, to two different dimensions, called “Age-Diagnosis” and “Age-Location”, in a hypercube. A set of points in a hypercube along with operators and additional structures in the cube is what enables multidimensional analysis or OLAP. The operators and structures may include, inter alia, hierarchies, measures, aggregation or grouping operators, projections, slice and dice, drill-down or roll-up. Commonly used implementation techniques include star and snowflake schema databases as OLAP servers. A hypercube may consist of selected dimensions, their associated join criteria and join operators, together with additional selected structures, such as hierarchies and level sets, and also the various relations used to generate points, i.e., populate, the hypercube. A hypercube may be represented in different forms revealing all or some of its structure. Examples of hypercube models include the star and snowflake schemas, mentioned above, and used in connection with relational OLAP. Many other representations exist such as the ones found in multidimensional databases, e.g., Oracle Express from Oracle Inc or Hyperion Essbase from Hyperion Solutions. Domains and Dimensions FIG. 3 shows an exemplification of domains. It illustrates an example of a domain 300 with attributes relating to age. The example distinguishes between the attributes 302 and identifiers 301 for the attributes associated with the domain. The identifier may be an integer but the attributes may be of other data types. Other information available about the values on the domain and associated with the identifiers or attributes may include a description of the data type, e.g., number, string, integer, year etc, of attributes in the domain. Dimensions, e.g., the dimensions numbered by 201 , inherit attributes, either directly or through references to domains or their identifiers. A dimension, here, refers to a structure that is set up in multidimensional analysis and may be nothing more than an instance of a domain, a subset of a domain or the domain itself. Measurements about a given domain may contain identifiers or other references to attributes on various levels, e.g., a specific age-in-days attribute, an age-in-years attribute or just a reference to the “Adult” attribute. Definitions of domains are stored in system 100 according to the present invention. Level Sets FIG. 4 shows an exemplification of hierarchies and their level sets ( 400 ). It shows two hierarchies 405 and 410 for the same domain. Hierarchies can be regarded as special binary relations on domains. Hierarchy 405 is the relation formed by the set of 2-vectors of identifiers ( 1 , 2 ), ( 2 , 7 ), ( 5 , 2 ), ( 6 , 7 ) ( 8 , 1 ) and ( 9 , 1 ). Similarly 410 is the relation defined by the tuples ( 1 , 3 ), ( 3 , 10 ), ( 4 , 6 ), ( 5 , 3 ), ( 8 , 4 ) and ( 9 , 4 ). The hierarchies define a hierarchical function on the domain, e.g., the hierarchical function for 405 maps 1 to 2 , 2 to 7 , 5 to 2 , 6 to 7 , 8 to 1 and 9 to 1 . Other values in the domain may be mapped to some designated element (commonly denoted by the symbol NA), indicating that they are not represented on higher levels. These structures may be predefined in the system, but hierarchies and level set structures may also by created and edited by a user of the system. The structures are stored in tables or files and form a part of the system 100 . Level sets, corresponding to a hierarchy, as referred to in the current specifications, form a sequence of subsets of values from the domain such that the hierarchical function maps an element on a given level (set) to the subsequent level (set) if the element is an input for the hierarchical function. In other words a level set may contain elements that are from the domain but do not attach to the hierarchical structure, such as the element “ 10 ” from level set 404 as indicated on the drawing. The sets 401 , 402 , 403 and 404 form level sets for hierarchy 405 from lowest to highest level respectively. Similarly, the sets 406 , 407 , 408 and 409 form level sets, from lowest to highest for hierarchy 410 . The two level set structures chosen are the same even though the hierarchies are different, i.e., the lowest levels 401 and 406 are the same, both contain just the identifiers 8 and 9 , the next levels 402 and 407 are also the same and so on. The elements in level sets may be attributes, identifiers or other references to the values on the domain. Depth-of-Field FIG. 5 is a block diagram describing an online depth-of-field operator for multidimensional analysis according to the present invention. It describes processes that adjust measurements (hence 500 ) in order to increase the number of possible points, i.e., composed measurements, in the multidimensional processing of a hypercube. The processes may be controlled by selected hierarchies or binary relations on selected dimensions. The operator can be applied to any dimension using any hierarchy on the dimension and between any levels of the hierarchy. It may be applied to several dimensions simultaneously. The process ( 500 ) may be initiated, repeated and controlled by a user, directly or indirectly, by selecting the required hierarchies, levels and so on. It may also be initiate by the system and controlled by additional metadata available about the measurements or hierarchies. The block 501 represents a set of initial measurements. The measurements may be extracted from a database and be of various types, i.e., from the various relations stored in the system ( 100 ). The measurements may also be composed or derived such as measurements resulting from calculations or other processes that define relations. This may furthermore include measurements derived from previous applications of the processes denoted by 500 , 600 or 700 and described herein. The set 501 may be located in memory or in other storage devices and it may furthermore be implicitly defined by including references to relations or subsets thereof. The starting point for the process is an initial set of measurements about dimensions selected for multidimensional processing in a hypercube. Which measurements are included in 501 may be determined by the system from the dimensions of the hypercube being populated with points. For example, by including relations that are supported by subsets of the dimensions. It can also be left to the user, performing the multidimensional analysis in the system, to select or define the relations included, or a combination of both. The text 502 specifies that in order to perform the process ( 500 ) between selected level sets of a hierarchy on a given dimension the system ( 100 ) needs to locate the measurements specified in 501 that are about values on the first level set selected. For clarity (only) the dimension selected is numbered as the k-th dimension, see 502 , included in the analysis. In addition, the lower and higher levels selected from a level set structure of the hierarchy are numbered by i and i+1, respectively, for clarity in the description. Continuing the description of process 500 , called depth-of-field adjustment here, block 503 specifies that new measurements are generated from the ones identified in 502 by replacing values from the first level set (i.e., the i-th one) selected, with values from the second level set selected (i.e., numbered by i+1) on the k-th dimension. This is done by replacing values on the first level, that map to the second level, with their corresponding images under the hierarchical function. Values from other dimensions in the measurements are not changed. The text block 504 indicates that the new measurements generated are added to the system, at least temporarily, e.g., in memory. The set of new measurements 505 may be combined with the previously defined ones in 501 , i.e., modifying or creating new relations, or with a different set of measurements in order to allow new compositions, i.e., joins, to take place. In order to make the processes 500 reversible a reference to the new measurements may be maintained, for example by numbering the new measurements and storing the reference numbers. The original and the new measurements are then used for further processing in the multidimensional analysis, e.g., to create new points to populate the hypercube with as described in connection with FIG. 2 and in connection with FIG. 7 . Examples The depth-of-field operator/process described above may be used to vary the level of granularity of measurements. In many cases, measurements will be entered at such a fine granularity that they cannot be combined to form points without additional information, even when appropriate for the purpose of a particular analysis. An example of this could be a height measurement for someone that is 9234 days old and a weight measurement for the same person when she is 9190 days old. In order to combine a large quantity of such measurements the user of the system needs to be able to use a different criteria for comparison than “age in days”, assuming that a large part of the measurements is entered at that level of granularity. This is done by applying the above process to the age dimension between level sets L 0 and L 1 with increasing granularity. Here, L 1 could contain age intervals such as “Adult” and L 0 contain age represented by a finer granularity such as “age in days”; the two levels being connected by the appropriate hierarchy. The result of adjusting the depth-of-field between the levels, as described above, becomes clear when analyzing the projections of points onto the two dimensional height and weight plane for different levels. Restricting the age dimension to values in L 0 or L 1 before the depth-of-field adjustment would only reveal points where measurements can be joined based on their original granularity. This might be a small set of points. Restricting the age dimension to L 1 after the process might on the other hand reveal many more points, in the two dimensional projection, that where omitted before. The increased number of points displayed in the projection in the later case may reveal a connection between the two variables (height and weight) where as such a connection may very well not have been displayed using the original points only. Another example involves measurements about individuals indicating location in terms of zip codes and measurements about water quality where location is entered in terms of larger regions. In order to be able to discover how pollution affects individuals, using multidimensional analysis, we equate location based on the region definition using the depth-of-field operator as before etc. Blowup Operator FIG. 6 is a block diagram describing an online blowup operator for multidimensional analysis according to the present invention. The process ( 600 ) described is divided into two related sub-processes or operators. Both of the sub-processes are controlled by hierarchies and level sets of the hierarchies on a given dimension. The first sub-process starts with an initial set of measurements 601 and creates new instances, i.e., copies or equivalent, of some of the initial measurements with support on new instances of the original dimensions as described by blocks 602 , 603 , 604 and 605 and determined by the level sets and hierarchies involved. The second sub-process starts with a hierarchical structure 610 on the dimensions and converts the hierarchical structure into a relation as described by blocks 611 , 612 , 613 and 614 . The relation generated by the second sub-process connects the original measurements to the new instances generated by the first sub-process. Both sub-processes may be repeated for several hierarchies with compatible level set structures for the same dimension and level as described below. The blowup operator or process, as referred to here, may increase the number of dimensions in the multidimensional analysis proportionally to the number of hierarchies involved, also as described below. It can be applied to any level set of any dimension in the analysis. The starting point for the process is an initial set of measurements about dimensions selected for multidimensional processing in a hypercube. The block 601 represents a set of initial measurements, similar to the initial set described by block 501 on FIG. 5 . The process ( 600 ) may be initiated, repeated and controlled by a user, directly or indirectly, by selecting the required hierarchies, levels and so on similarly to what was described for process 500 . The user of the system, performing the multidimensional analysis, selects a dimension and a particular level on some level set structure for the dimension and identifies one or more hierarchies sharing the level get structure. In many cases, there may be only one hierarchy for a given level set structure. Again, as in FIG. 5, we denote the dimension selected as the k-th dimension and the level selected as the i-th level in the level set structure, the subsequent level being identified as number i+1. This notation is for clarity only. Text block 602 identifies which measurements are copied to new instances on new dimensions in 603 . The measurements identified by 602 are measurements with values from the k-th dimension (i.e., the measurements are about the k-th dimension) where the values on the k-th dimension are on higher levels than the i-th level. This encompasses measurements about values on levels i+1, i+2 and so. Block 602 also identifies measurements that are not about the k-th dimension at all and therefore have no direct reference to it. In other words, all measurements not about level i or lower levels of the k-th dimension are identified as explained by the text 602 . Block 603 specifies that new instances of the original dimensions should be created and added to the pool of dimensions in the multidimensional analysis. Thus, possibly, doubling the number of dimensions in the hypercube structure. Finally, the measurements, identified by 602 above, are copied to new measurements with references, respectively, to these new dimensions instead of the original dimensions. For the cases when more than one hierarchical structure sharing the level set structure is selected, process 603 is repeated for each of the hierarchies selected. Thereby, possibly adding still another instances of each of the original dimensions and copying the measurements identified by 602 to those new instances also. Each time this is repeated the connection between the new and the original dimensions needs to be maintained, and to which of the selected hierarchical structures the new dimensions correspond. This bookkeeping can be accomplished, for example, by naming the new dimensions by appending the names of the original dimensions with the name of the relevant hierarchy and level. Text block 604 indicates that the new generated measurements are added to the relations used to populate the hypercube. The set of new measurements 605 may be stored with the previously defined ones in 601 , adding new relations, for further multidimensional processing. The second sub-process starts with 610 showing one of the hierarchical structures selected by the user as explained above. The sub-process is repeated for each hierarchy selected. Text block 611 indicates that information about the hierarchical structure on the i-th level and on higher levels needs to be made available. The next step, as indicated by block 612 , is to transform the hierarchical information into measurements. This new relation connects the original instance of the k-th dimension to the new instance of the k-th dimension created according to 603 for the hierarchy 610 . This is done by populating a binary relation over the dimensions, i.e., the original and the new instance of the k-th dimension. The relation generated by 612 contains measurements representing the graph of the hierarchical function for elements above and on the i-th level of the level set structure used in connection with the first sub-process above. In other words measurements where the first attribute, from the original k-dimension, is an element from the i-th and higher levels and the second attribute, from the new instance of the k-th dimension, is the corresponding image of the first element under the hierarchical function, if there is one. As before “NA” values, described above, are ignored. Blocks 613 and 614 indicate that the resulting binary relation, just described, is added to the set of relations and as before needs to be available for further processing, e.g., generation of points in the larger hypercube. The operator is generic and can be applied to any dimension and hierarchy available for use in the hypercube. Examples Start with a ternary relation with domains representing individuals, age and height, i.e., height measurements, and hierarchies representing the genealogy of the individuals. The hierarchies are “Mother” and “Father” representing mothers and fathers of individuals in the domain. The hierarchies are such that they share the same level set structure L 0 and L 1 . The lower level L 0 represents the latest generation of individuals, L 1 their parents and so on. The ternary relation being the initial set of measurements, 601 , chosen for the analysis in an initial hypercube definition with the three dimension (individuals, age and height). Applying the blowup process along the Father hierarchy starting at level L 0 generates a 6 dimensional hypercube with axes including, for example, the original one Height, representing height of individuals, and also another instance of that dimensions, “Height-Father”. The, now, six dimensional hypercube, after it has been populated with points resulting from the blowup process, may be projected onto the two dimensional plane determined by the Height and Height-Father dimensions. Doing so, for the different age groups, reveals to the person performing the multidimensional analysis the connection between these two attributes. The projection may be viewed as a two-dimensional scatter graph. The Mother hierarchy may also be used simultaneously with the Father hierarchy, since they share the same level set, producing a 9 dimensional hypercube with more information embedded into it. Furthermore, the process can be repeated for higher levels or for projections only. This simple example shows some of the usefulness of the blowup operator. On the other hand the operator is designed to be able to work with much more complicated initial sets than just the one relation above and some of the relations don't necessarily have to be (directly) about the (k-th in the above) dimension selected. Other examples include hierarchies that allow the user to compare attributes through development stages (such as by introducing levels on an age dimension representing neonate, infant, toddler, child, teen, adult etc). Furthermore the blowup operator, like other operators and processes shown in the current invention, can be used to analyze relations applicable to many different industries, e.g., telecommunications, finance, retail and so on. Ambiguity Resolution FIG. 7 is a block diagram describing an online syntheses programming technique for multidimensional analysis according to the present invention. In order to enable dimensions to have a “universal” meaning their implicit relation with each other has to be described. This can be achieved to a large degree by enforcing relations describing formulas and other predicable (i.e., not necessarily measured in a real life setting) structures connecting the dimensions in a hypercube. Process 700 (Online syntheses programming) describes a technique for modifying the join process (e.g. see FIG. 2) in multidimensional processing to dynamically account for internal connections between dimensions. Thereby, reducing the number of possible points in the hypercube that is being populated, by only allowing points that belong to subspaces defined by the internal connections. Process 700 starts with a set of measurements 701 used to populate a given hypercube structure with points using a join process similar to the join process described in connection with FIG. 2 . It also has access to a set of calculated relations 705 in the form of functions accepting as input attributes from some of the dimensions in the hypercube. The functions return other attributes on dimensions in the cube or Boolean values. These calculated relations may for example be obtained by selecting from a, previously defined, set of such calculated relations all relations that can be expressed using the dimensions in the hypercube. It may also just contain a subset thereof determined by a hierarchical structure about the calculated relations containing information about which calculated relation cannot be used together. In the cases when a conflict occurs the system opts for the relation referred to on a higher level in the hierarchy. Other possible schemas for determining which relations need to be included in 705 may include input from the user of the system. The functions return new attributes about other dimensions in the hypercube, the combined input and output forms a set of related values. Among the calculated relations may also be Boolean expressions that reject or accept a set of input attributes from the dimensions of the hypercube. The relations in 701 may for example be obtained by applying (repeatedly) processes 500 and 600 , resulting in measurements such as 501 and 505 or 601 , 605 and 614 or a combination of both. The relations in 701 may require being grouped together into larger relations according to supporting dimensions, if more than one relation in 701 is supported by the same collection of dimensions in the hypercube. Herein, a collection of dimensions supporting a relation is said to determine the type of the relation, i.e., relations supported by a different set of dimensions are of different type. The preprocessing of relations in 701 involves concatenating relations of the same type into larger relation directly or indirectly. For example, by linking all the relations of the same type in 701 , into a new (virtual) relation. Text blocks 702 and 704 indicate that the measurements are joined into possibly longer composed measurements and eventually into points in the hypercube. The join process may use different join criteria and join operators for each dimension in the hypercube as described in connection with FIG. 2 . Block 702 indicates that measurements from 701 are composed, according to the join criteria selected for their supporting dimensions and using their associated join operators, until they describe input attributes for at least one of the functions in 705 . The input attributes are then used, as indicated by 704 , to generate new calculated measurements with related values from the input attributes and output attributes of the functions accepting the input values. In the case of a Boolean expression accepting the input attributes, it, i.e., the output of the function, is used to decide if the composed measurement should be rejected or not. The new calculated measurement can then simply be added to the measurements in 701 (as indicated by text block 706 ) or composed, using the join operators, immediately with the original (composed) measurement containing the input attributes. If the join fails, i.e., the measurements don't satisfy the join criteria selected (e.g., attributes don't match), then the original measurement is rejected. Bookkeeping of allowed compositions needs to be maintained, as indicated by block 703 since allowed composed measurements with defined attributes, determined by the join operators, about all the dimensions in the hypercube define the points in the hypercube. The system may be required to consider all the preprocessed relations in 701 and all calculated relations in 705 also, i.e., the longest path. This may be achieved by sequentially numbering the preprocessed relations (e.g., the numbering in 202 ) and not skipping using any of the preprocessed relations in the join process even when fewer of the relations already define the required attributes (e.g., measurements 204 , 205 and 206 ). When using the default (natural) join criterion and operator, this will require the points generated to be such that if they are projected to dimensions already used to support a relation (i.e., of a specific type) in 701 then that projection will already exist in the corresponding preprocessed relation for the type. Herein, we will refer to taking the longest path when generating the points in the hypercube, as mentioned above, as implying that the points in the hypercube being contradiction free—with respect to existing relation types in 701 . Examples Given a user defined eight-dimensional hypercube with the (self-explanatory) dimensions: Individual, Time, Birthday, Age-Diagnosis, Age-Location, Diagnosis, Location and Pollution. Set the relations in 701 to be Birthday, Diagnosis, Whereabouts and Pollution. Extracting individual measurements from each of the relations, respectively, might reveal measurements such as M 1 =(id, birthday), M 2 =(id, age.diagnosed, lung-cancer), M 3 =(id, age.location, location) and M 4 =(location, time, air-quality). Here id, time, birthday, age.diagnosed, age.location, lung-cancer, location and air-quality respectively represent fixed attributes from the dimensions in the hypercube. The measurements M 1 , M 2 , M 3 and M 4 can be joined, per se, using the natural join to form a point in the hypercube with the eight attributes shown. On the other hand, this may not be meaningful at all, unless a calculated relation is present enforcing the implicit connections between the dimensions Birthday, Time and the two Age dimensions. Therefore, if available to the system, it would automatically add the bee calculated relations C 1 and C 2 to 705 representing the connections, e.g., birthday+age.diagnosed=time and birthday+age.location=time respectively, in one form or another. With those new relations C 1 and C 2 in 705 the point, i.e., (id, time, birthday, age.diagnosed, age.location, lung-cancer, location, air-quality), with the attributes shown will not be formed in the eight dimensional hypercube unless it satisfies C 1 and C 2 also. On the other hand, even though these four dimensions appear to be related for most studies many other relations are possible than the one presented above. Depending on the other dimensions in the hypercube. In order for the system to choose from the other possible calculated relations, a predefined hierarchical structure among the calculated relations is used, as shown below. Assuming now that the user performing the multidimensional analysis additionally has placed an “offset” dimension, called Offset, in the hypercube. The dimension represents offset in age. Assuming also then, that 701 contains a unary relation with integer attributes from the Offset dimension, say 0 to 20, representing years. This, depending on availability of calculated relations, results in the system having to evaluate which of the relations C 1 or C 2 above or, another calculated relation, C 3 to use. The calculated relation C3 representing the formula age.diagnosed=age.location+offset in one form or another. A “reasonably” defined hierarchical structure among the calculated relations would opt for using C 2 and C 3 in 705 . Score Tables FIG. 8 is an illustration of processes used to record composed measurements. The table 801 contains information recorded in process 700 and describes how the composed measurements may be recorded by 703 . The table has one column for each preprocessed relation, i.e., relation type, in 701 shown here numbered from 1 to n ( 802 ). Each completed row in the table corresponds to one point in the hypercube used in the multidimensional analysis. The rows are numbered sequentially as indicated by 804 . The entries 803 in the table are references to corresponding measurements in 701 and may, for example, contain a reference number or simply refer to memory locations for the measurements. The table 801 allows the system to track more than just dimension attributes, such as done by table 806 , namely it refers directly to the measurements in the system. Consequently removing a measurement from any of the relations in 701 can be done, online, without starting the analysis process again. This is achieved by simply removing only the points (rows) in 801 that refer to the measurement that is being removed. Adding a new measurement to any of the relations in 701 simply results in zero or more additional rows in 801 and can be done online by completing the additional rows with references to other compatible measurements in 701 starting with the one that is being added. The entry m(i,j) from 803 refers to, as explained above, a measurement from the preprocessed relation numbered by j in 701 and where i is the corresponding row number. Each row in 801 contains measurements that can be composed to form a point according to the join criteria for the dimensions. The table 801 contains all such rows resulting from the set of measurements being used ( 701 ). Table 801 may be populated in a recursive fashion starting from the first entry, e.g., m( 1 , 1 ). The rows are extended by adding measurements compatible (using the join criteria) with the existing ones already in the row, If no compatible measurement for a particular column and row in the table is found then the system replaces the measurement in the previous column with the next available measurement before trying again and so on. This continues until all possible points have been generated. The system may be made contradiction free, as defined above, by only including fully completed rows, i.e. no “nulls”. Text block 805 indicates that table 801 may be used to populate the fact table 806 containing one column for each dimension, numbered by 1 to N as indicated by 807 . When the default (natural) join criterion and operator is used for all the dimensions in the hypercube the rows in 801 are simply converted to a sequence of values by looking up the related values determined by the measurements in the rows. These values are then stored, respectively according to dimension, in the next available row in table 806 . At the game time, repeated rows in 806 may be avoided. For a dimension using different join operators, e.g., summation, the operator is applied to the values from the dimension extracted from the measurements before being stored in the fact table as before. The values (shown as 808 ) may be attributes or identifiers depending on the dimension tables used in connection with the fact table. In order for table 806 to be considered a valid fact table the user of the system needs to select one attribute column as the “fact” item, as indicated by 809 . This may also be accomplished by the system itself, choosing the “fact” attribute from a list of default such dimensions. Such a list would normally consist of dimensions containing numeric attributes. Grouping and Dimensions Tables FIG. 9 is a high level illustration of a grouping technique that allows measurements to be supported on different and varying levels according to the present invention. FIG. 9 illustrates a generic dimension 903 in a hypercube. Associated with the dimension is a level set structure for a hierarchy designated for grouping of values by the user of the system. The different level sets are indicated by 904 , 905 and 906 . Two different measurements 901 and 902 are shown each taking one of their values from the dimension. The values are shown on different level sets. Grouping values, according to hierarchical structures, in a hypercube, without forcing measurements to be entered on compatible level sets (e.g., lowest) may be enabled as follows: For a fixed point, identified for grouping, in the hypercube the system identifies which points are on lower, or same, levels and are carried by the hierarchical functions to the fixed point identified. Different hierarchical functions may be applied to attributes from different dimensions, as determined by the hierarchical structures set up for each dimension in the cube. Furthermore, the hierarchical functions may be applied iteratively or not at all to the different attributes as determined by the number of level sets between a given attribute and the corresponding attribute from the fixed point selected. The information about the grouping may be stored separately as a sequence of numbers listing the rows in table 801 that are identified in the process. A reference needs to be maintained between the list and the grouping point, for example by numbering all such points and connecting the lists and the numbers etc. Using the information the system may then display calculations associated with the points using one or more of the attributes of the measurements identified in the lists. The calculations may be initiated by the user specifying aggregation operators, as explained in connection with FIG. 11 . An example includes counting the number of different attributes on a specific dimension. Another example may include using more complicate operations applied to the attributes requiring information stored elsewhere in system 100 , such as kinship measures requiring addition genealogical information. The link that is maintained with the measurements in 801 also enables any aggregation operator to access other information (e.g., cost) not necessarily stored in the hypercube model but linked to the individual measurements in 801 . Grouping may be implemented for a set of points by identifying which level sets on each dimension should be considered aggregation or grouping levels and then repeating the grouping process above for points in the hypercube with attributes from these levels. Grouping can be made more efficient in this case by, for example, storing additional information about the rows in 801 such that points (rows) with attributes on the same level set on each of the dimensions are quickly located. FIG. 10 is an illustration of a process used to convert hierarchies to dimension tables according to the present invention. Dimension tables are used, in the prior art, in connection with fact tables, e.g., 806 . They store identifiers connecting the columns in fact tables, excluding the fact column (e.g. 809 ), to attributes and describe the grouping of the fact table according to attributes on higher levels. In a ROLAP system using a star or snowflake schema a column in a fact table may be connected to a dimension table through an entity relationship. This requires that the values in the fact table be entered at the lowest level in the grouping hierarchy. This grouping is more restricted than the one described above since it does not allow measurements to be entered using values from higher level sets. In order to enable grouping of table 806 through a standard star or snowflake schema the system may modify the grouping hierarchies, e.g., selected by the user, for the dimensions in the hypercube. The hierarchies are modified as explained by text box 1002 and as shown by the example of a hierarchical function 1003 and its modified version 1001 . The modified hierarchical function 1001 is such that elements on higher levels are grouping elements and are always images of elements from lower levels in the hierarchy. Such a regular hierarchy is translated into dimension table(s) in a star or snowflake schema in a way that is well established in the prior art. The modification of the hierarchical functions, e.g., the process 1002 , may be performed as follows: Starting from the highest level of the hierarchy the system identifies all elements on that level. For these elements (e.g., 7 in 1003 ) the system adds new instances of the elements identified, represented with new elements (e.g. 7 ′ in 1001 ) on the previous lower level and connects the new element to the original one by mapping the new element to the old (e.g., 7 ′ maps to 7 ). The attribute corresponding to the new identifier (e.g., 7 ′) is kept the same as the attribute for the old identifier on the higher level (e.g., 7 ). This process then continues for the second highest level, adding elements to the third highest level, and so on until the last level has been populated with new additional elements representing elements starting at higher levels. In other words, elements on higher levels are extended to the lowest level. When converting the new modified hierarchical function to a dimension table, the system may use the same identifiers (e.g. 7 for 7 ′ and 7 ″ in 1001 ) and attributes for all the corresponding new elements introduced on lower levels to represent the same higher-level element. Thereby, the elements in the (non-fact) columns in fact table 806 only refer to lowest level elements in the dimension tables generated, as required. The person skilled in the art will realize, from the above description, that the intermediate step of creating the modified hierarchy (e.g. 1001 ) can be regarded also as a description of how to create the dimension tables directly, without introducing additional hierarchical structures into the system, such as 1001 . The exemplary hierarchical function 1003 is shown as a relation with two columns where the elements from the first column map to corresponding elements shown in the second column. The lowest level set for the hierarchy may be determined from the function and in the case of 1003 consists of the elements 1 and 2 , the next level set consists of the elements 3 , 4 , 5 and 6 and the highest level set contains 7 only. The modification of the hierarchy described above and illustrated by 1002 results in the function 1001 with lowest level set consisting of lowest level 1 , 2 , 3 ′, 4 ′, 5 ′, 6 ′ and 7 ″ the next level contains 3 , 4 , 5 , 6 and 7 ′ and the highest level contains 7 only. The process described by 1002 may be further enhanced by only extending elements from higher levels to the lowest level, as described above, for elements that actually appear as keys in table 806 . Fact Dimension and Fact Tables FIG. 11 shows an exemplification of a fact dimension according to the present invention. The table 806 , representing points in the hypercube, is converted into a fact table by having one column ( 809 ) identified as a “fact” attribute as explained above. This, on the other hand, may not be the desired “fact” that the user performing the multidimensional analysis is interested in working with. In working with measurements the desired quantifying fact may not even be well defined, or meaningful, at atom or row level in table 806 . Furthermore, it may be most useful to have more than one fact displayed in the fact table. This may be achieved as described below. Instead of identifying one row, i.e., 809 , containing the fact item, two more columns may be added to table 806 . One of the columns (e.g., the last column) is the new fact column and the other column would contain identifiers from a new separate dimension, called here the fact dimension. The fact dimension, e.g., 1101 , has attributes referring to measures or observations ( 1101 ). The observations are stored in system 100 as functions that accept as input references, either direct or with the aid of additional structures such as the dimension tables or otherwise, to a set of attributes in 806 identified by the grouping process. Additional parameters may be passed to the observations also. The observations return a value that is then recorded in the corresponding fact column. Generating dimension tables for the fact dimension is straightforward, it does not need to have any additional levels, just the lowest level with the measure names as attributes. The modified fact table, i.e., 806 with the two additional columns described above, may then be populated using the corresponding observation functions described above. More precisely, for each row in 806 the extended fact table contains rows with the same attributes as in 806 , but appended with a reference to the fact dimension in one of the two new columns. The value of applying the corresponding observation to the (attributes in the) row in 806 in then recorded in the other additional column, called fact column above. A similar process may also be used to produce fully or partly aggregated summary tables, using the measures referred to by the fact dimension. Automata and Axes Matrices FIG. 12 is an illustration of the definitions needed to generate a hypercube from measurements according to the present invention. The methods described above allow the system directed by a user performing the multidimensional analysis to generate and populate a hypercube using methods such as 500 , 600 and 700 . The system may eventually be directed to convert the structures into fact table schemas as explained in connection with FIGS. 8, 9 , 10 and 11 . In order to automate the processes further additional information may be stored, i.e., metadata, such as the information stored in the structure 1203 , called axes matrix here. These additional structures may be used to automatically direct the system to repeatedly apply operators such as 500 , 600 and the process 700 and eventually generate fact (e.g., 806 ) and dimension tables for an initial set of relations, as described already. The illustration shown on FIG. 12 is achieved by exemplifying the concepts. Domain 1202 is shown containing identifiers grouped according to level sets ( 1201 ) for one or more selected hierarchies for the domain. Associated to the domain are one or more predefined structures, such as the axes matrix 1203 , that specify how measurements about the domain may be processed in multidimensional analysis, and which hierarchies and level sets to use. The exemplary structure 1203 is a matrix containing four rows each representing one dimension instance of the domain 1202 . Columns 1 , 3 , 5 and 7 contain references to the four level sets that the domain has. The first row, starting in the upper left comer, identifies the first instance of domain 1201 as a dimension in the hypercube. Entries in the row specify which level sets should not be used for aggregation, i.e., L 1 and L 2 . It is also specified how operator 500 (depth-of-field) should be applied, i.e., between levels L 0 and L 1 . It is also shown what elements are included from the domain, i.e., all the four level sets are shown to be included. Furthermore it is specified where grouping of values takes place, i.e., starting from level L 1 . The second line specifies the second instance of the domain as a dimension in the hypercube, this time it does not include values from the lowest level. The beginning of the line indicates that the second instance is obtained from the first by process 600 (blowup) and so on. Similarly, the third line shows how the third instance of the domain is obtained from the second by a blowup process as before. Axes matrices may be selected from a predefined set of such structures, or defined, by the user performing the multidimensional analysis. The user may select different axes matrices for the various domains holding values from measurements in the initial set of relations. Thereby, implicitly defining complicated axes structures in a hypercube together with simultaneously determining other processing of measurements used to populate the hypercube. These and the methods described above allow the user to populate a data warehouse with a minimal effort. While this invention has been particularly shown and described with references to preferred embodiments thereof, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the scope of the invention encompassed by the appended claims.

4y

This application is a continuation, of application Ser. No. 07/899,866, filed Jun. 17, 1992. The invention relates to a pharmaceutical preparation containing protein C. BACKGROUND OF THE INVENTION Many surgical procedures increase the risk of venous and arterial thromboses and of thromboembolism. Arterial and venous thromboses also may be caused by diseases. However, antithrombotic and thrombolytic therapies involve undesired side effects, such as bleeding or reocclusion. The thrombolytic activity of substances, such as t-PA, urokinase, streptokinase or plasminogen, is based on the release of plasmin, which enables the dissolution of thrombi. At the same time, it is observed that thrombin is generated when administering thrombolytically active substances. The thrombin generation and subsequent reocclusion are presumed to be a generally undesired side effect of successful thrombolysis (Circulation 83, 937-944, (1991)). In addition to an elevated thrombin activity, a change of the protein C concentration in blood is observed in thrombolysis patients (Seminars in Thrombosis and Hemostasis 16, 242-244 (1990)). Therapy is effected either with t-PA or with heparin or with a combination of t-PA and heparin. A reduction of the protein C concentration is observed only when administering t-PA-containing preparations. The direct degradation of protein C by t-PA or plasmin has not been considered, however. In connection with undesired side effects of thrombolysis, it is suggested in EP-A - 0 318 201 to use activated protein C (aPC) alone or in combination with a thrombolytic agent to prevent acute arterial thrombotic occlusions, thromboembolism or stenosis. aPC is known to be an anticoagulatively effective enzyme, which, on the one hand, inhibits the formation of thrombin due to the proteolytic degradation of activated coagulation factor V and activated coagulation factor VIII and, on the other hand, supports fibrinolysis. For this reason, the dose of thrombolytic agent may be reduced. Likewise, it is suggested in Blood 74, Suppl. 1, 50a, Abstract 176 (1989) to use a combined preparation containg aPC and urokinase to prevent the formation of thrombi in order to reduce the thrombolytic or antithrombotic doses of urokinase and simultaneously combat bleeding complications occurring in thrombolysis therapies. However, the administration of activated protein C suffers the disadvantage that the tendency to bleeding is favored by the immediate anticoagulant effect of aPC. SUMMARY OF THE INVENTION The invention has as its object to eliminate this disadvantage and to provide a pharmaceutical preparation that prevents reocclusion caused by an elevated thrombin activity after thrombolysis therapy has been carried out. The preparation according to the invention contains protein C and a thrombolytically active substance that does not activate protein C. It has been shown that the preparation according to the invention enables successful thrombolysis therapy without the risk of reocclusion. Urokinase, tPA, Lys-plasminogen or streptokinase are particularly suitable as thrombolytically active substances. Consequently, the invention also relates to the use of a thrombolytically active substance unable to activate protein C, in combination with protein C, to produce a drug for the treatment of thromboses and for the prevention of reocclusion. The invention is based on the findings that plasmin generated by therapeutic thrombolytics not only degrades fibrin, but surprisingly also degrades protein C at the very high concentrations applied during thrombolysis therapy, thus provoking protein C deficiency and inducing hypercoagulability. This may be prevented by administering the thrombolytically active substance in combination with protein C or by administering protein C in the course of thrombolysis therapy, i.e., prior to, during and/or after thrombolysis therapy. Preferably, protein C is contained in the preparation according to the invention at 10 to 50 U/mg protein. When ready for application, it should contain 90 to 450 U/ml. The content of thrombolytic agent in the preparation according to the invention appropriately is chosen so that usual amounts will be administered when applied. The protein C-containing preparation according to the invention may be administered as an injection (30 to 80 U/kg) two or three times a day or as a continuous infusion (15 to 30 U/kg/h). The invention will be described in more detail in the following. BRIEF DESCRIPTION OF THE FIGURE FIG. 1 depicts the degradation of Protein C by Plasmin. DETAILED DESCRIPTION OF THE INVENTION Preparation of Protein C Highly pure protein C was recovered from a crude protein C fraction obtained from commercially available prothrombin complex concentrate. Purification was effected by affinity chromatography by means of monoclonal antibodies. Monoclonal anti-protein C antibodies were produced as follows: BALB/C mice were immunized with 100 μg human protein C by intraperitoneal injection at two-week intervals. After six weeks, another 50 μg of human protein C was injected and fusion was carried out three days later. The myeloma cell line (P3-X-63-AG8-653, 1.5×10 7 cells) was mixed with 1.7×10 8 mouse spleen cells and fused according to the modified method of Kohler & Milstein by using PEG 1500 (Kohler G., Milstein C., Nature 256 (1975), 495-497). Positive clones, assayed by means of ELISA, were subcloned twice. Ascites production was effected by injection of 5×10 6 hybridoma cells per BALB/C mouse two weeks after Pristan treatment. The immunoglobulin was purified from ascites by means of ammonium sulfate precipitation and subsequent chromatography on QAE-Sephadex and, further, by chromatography on Sephadex G200. To reduce the risk of transmission of murine viruses, the antibody was subjected to a further virus inactivation step prior to immobilization. The monoclonal protein C antibodies thus obtained were coupled to CNBr-activated Sepharose 4B (Pharmacia). The following buffers were used for the purification of protein C by means of affinity chromatography: Adsorption buffer: 20 mM Tris, 2 mM EDTA, 0.25M NaCl and 5 mM benzamidine; Washing buffer: 20 mM Tris, 1M NaCl, 2 mM benzamidine, 2 mM EDTA, pH 7.4; Elution buffer: 3M NaSCN, 20 mM Tris, 1M NaCl, 0.5 mM benzamidine, 2 mM EDTA. In detail: The prothrombin complex concentrate was dissolved in the adsorption buffer, with approximately 10 g of the prothrombin complex concentrate being employed for a 20 ml monoclonal antibody column. Subsequently, the dissolved prothrombin complex concentrate was filtered, centrifuged at 20,000 r.p.m. for 15 min and sterilely filtered through a 0.8 μm filter. The sterilely filtered and dissolved prothrombin complex concentrate was applied to the column at a flow rate of 10 ml/h. Subsequently, the column was washed free of protein with the washing buffer, and finally the bound protein C was eluted by means of the elution buffer at a flow rate of 5 ml/h and the fractions were collected. The eluted protein C was dialyzed against a buffer (0.2 mol/l Tris, 0.15M glycine and 1 mM EDTA, pH 8.3). Protein C antigen concentration was determined using the method described by C. B. Laurell, Scand. J. Clin. Lab. Invest. 29, Suppl. 124:21-37 (1972), and protein C activity was determined using Protac activation. The protein C eluate obtained was finished to a pharmaceutically applicable preparation in the following manner: The eluate was first subjected to ultrafiltration and diafiltration steps. Diafiltration was carried out with a buffer containing 150 mmol NaCl and 15 mmol trisodium citrate.2H 2 O per liter, at a pH of 7.4. The obtained filtrate was freeze-dried and virus inactivated by a one-hour vapor treatment at 80° C.±5° C. and at 1375±35 mbar. The lyophilized, virus inactivated material was then dissolved in a sterile isotonic NaCl solution and potentially present antibodies or serum amyloid P were eliminated by means of ion exchange chromatography on Q-Sepharose. The purified solution was concentrated by means of an additional ultrafiltration and diafiltration step. After this step, 10 g albumin, 150 mmol NaCl and 15 mmol trisodium citrate per liter were added to the solution obtained. The pH of the solution was 7.5. Neither murine immunoglobulin nor factors II, VII, IX and X could be detected. Subsequently, the solution was sterilely filtered, filled in containers and lyophilized. The specific activity was 14 units protein C per mg of protein. One unit of protein C activity is defined as the protein C activity in 1 ml normal plasma and is calibrated against the first international standard of protein C. An amidolytic assay was used as the activity test, wherein protein C was activated by means of Protac (Pentapharm), a common protein C activator produced from a snake venom preparation. Time-dependent degradation of protein C Protein C was treated with plasmin and the degradation was observed by means of immunoblotting. To this end, 270 μl of a protein C-containing solution (8 μg/ml) were incubated with 270 μl plasmin (1 CU/ml) at 37° C. Accordingly, the substrate/enzyme ratio was 8:1 (μg/CU). After only 60 minutes, no protein C could be amidolytically detected any longer. Dose-dependent degradation of protein C In order to investigate the dose-dependent degradation of plasmatic protein C, 50 μl plasmin were each added to 50 μl human citrated plasma at concentrations of 10, 5, 3, 1.5 and 0.5 CU/ml, respectively. After a reaction time of 10 minutes, 50 μl antithrombin III-heparin complex (10 U ATIII, 50 U heparin per ml) were each added. By this addition, the reaction is stopped. Protein C was amidolytically determined with the specific chromogenic substrate S 2366 (Kabi) upon activation with "PROTAC" (Pentapharm). For comparison, plasmatic protein C without plasmin addition was treated in parallel. The results are apparent from the Figure (abscissa: CU plasmin; ordinate: % protein C activity). The Figure illustrates that protein C is completely degraded after only 10 minutes if a solution containing 10 CU/ml plasmin has been added.

4y

This application claims priority from U.S. Provisional Application No. 60/212,949 filed Jun. 21, 2000. FIELD OF THE INVENTION Air cooling devices, more specifically, an air cooling device comprising an endothermic substrate bearing container with an air circulation means for circulating air from outside the container, about the endothermic substrate and, chilled, exhausted from the container. BACKGROUND Humans can function optimally, in comfort, over only a fairly narrow ambient temperature range. Adjustment of the amount and type of clothing will afford some relief from ambient temperature, especially adding clothing for comfort in a cold environment. However, as temperature rises conditioning the ambient air, typically by some form of heat extraction often, is the only solution to maintaining a comfortable, tolerable air temperature. Typically, such heat extraction is performed by air conditioners. Air conditioners operate on the principle of heat absorption as a composition such as freon or other refrigerant changes phase from a liquid to a gas. Water, for example, will absorb about 550 calories of heat per gram when changing from water at 100° C. to water vapor at 100° C. (at one atmosphere of pressure). On the other hand, one gram of water will release 540 calories of heat when changing from water vapor at 100° C. to liquid water at 100° C. Air conditioners, however, are heavy, expensive and complex. Also, they require compressors to provide energy to power the gas to liquid phase change. Furthermore, they are designed to condition air masses defined by buildings or vehicle structures such as a room of a building or an interior compartment of a vehicle, rather than conditioning the air directly adjacent to the body of an occupant, that is, the occupant's “microenvironment”. Air conditioners are undesirable, for example, in cooling a cabin of a small or light aircraft such as a 2, 4 or 6 place airplane. In such light aircraft, there is a fairly small cabin space and anything that adds weight to the aircraft decreases its performance and payload. Thus, many light aircraft do not have air conditioning systems. Moreover, complicating this deficiency is the often limited ability to move air between the outside and the inside of the aircraft via ducts or windows. Thus, it may often get quite warm in the small interior cabin space of a light aircraft, especially when it is parked or tied down for a period of time on an airport apron. The warm air cabin environment of a light aircraft is not conducive to the concentration required for the pilot to operate the aircraft, especially during critical take-off or landing procedures. After the aircraft climbs to altitude, the outside air is usually sufficient to cool, even with small ducts, the interior of the aircraft cabin. However, this does not help when the aircraft has been sitting for a period of time in the hot air on the ground. OBJECT OF THE INVENTION What is needed and has heretofore been unavailable is a small, light, efficient, simple and inexpensive device for cooling a small cabin area or the occupant's microenvironment. SUMMARY OF THE INVENTION Applicant provides for these and other objects of the invention by providing a light, inexpensive air cooling and distribution system for use in a vehicle or with the microenvironment of an occupant. Applicant provides for these and other objects by providing an air cooling device which is capable of cooling either cabin air or the occupant's microenvironment through the use of a heat absorbing mass. Applicant achieves these and other objects by providing a small, light, air cooling device comprising an insulated container containing an endothermic substrate which will absorb heat upon changing phase and, which further includes a means for distributing ambient air across the endothermic substrate and distributing the cooled air. Applicant provides to these and other objects by providing a small inexpensive lightweight air distribution cooler distribution system for a vehicle that is powered by the vehicle's electrical system. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a cross section elevational view of Applicant's air cooling device with masses of ice supported on a frame in the container thereof. FIG. 1A is a cross sectional device of Applicant's air cooling device with some of the ice melted and showing the blower motor energized and air being drawn through the device. FIG. 1B is a front elevational view of Applicant's air cooling device. FIG. 2 is a side elevational view of Applicant's air cooling device. FIG. 3 is a exploded perspective view of the frame that is incorporated in the container of Applicant's cooling device. FIG. 4 is a top elevational view of the blower motor inlet of Applicant's air cooling device. FIG. 5 is a perspective elevational view of the drop-in box of Applicant's present invention. FIG. 6 is an alternative preferred embodiment of Applicant's air cooling device. FIG. 6A is a partial view of intake vents of Applicant's air cooling device which utilize door closer means. FIG. 7 is an illustration of an environment, here the interior of an aircraft, in which Applicant's air cooling device is used which illustration also features some of the additional features of Applicant's air cooling device. FIG. 8 is an alternative preferred embodiment of an outlet nozzle of Applicant's present invention. FIG. 9 is a perspective view of Applicant's air cooling device in use. FIG. 10 is a partial view in perspective, the anti-back flow valve of Applicant's present invention. FIG. 11 is an alternate preferred embodiment of Applicant's present invention. FIGS. 11A, 11 B and 11 C are alternate preferred embodiments of Applicant's present invention. FIG. 12 is an alternative preferred embodiment of a cooling device for use with microenvironmental cooling of an individual. FIGS. 13A, 13 B and 14 are all various adaptations of Applicant's micro cooling nozzles adapted for use with cooling air adjacent an individual. FIG. 15 is an alternate preferred embodiment of Applicant's novel device wherein the nozzle engages an article of clothing of the user for micro cooling. FIG. 16 is yet another adaptation of Applicant's air cooling device in a microenvironmental cooling adaptation. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of Applicant's novel heat reduction device ( 10 ) is found in FIGS. 1, 1 A, 1 B and 2 . With reference to these figures and those that follow, it is seen that Applicant provides a heat reduction system ( 10 ) comprising an insulated container, typically a six sided rectangular box ( 12 ), the box including a lid ( 14 ), typically insulated. The walls of the box ( 12 ) including where the removable lid ( 14 ) is fitted as part thereof are sealed except as provided with the vents, etc., as set forth below. The box ( 12 ) may be manufactured from one or more of the following: plastic, foam or any other suitable insulating material. The box may have any number of shapes including the rectangular shape illustrated. Typical dimensions for a rectangular box are approximately 15 ″ in width, 17 ″ in height and. Applicant's novel invention includes providing for placement within the box ( 12 ) (typically by removing the lid and placing it therein), an endothermic substrate ( 15 ). The endothermic substrate ( 15 ) is a mass of a composition which will absorb heat in undergoing a phase change, for example from a solid to a liquid or from a solid to a gas, which phase change and heat absorption typically occurs at temperatures below about 70° F. Illustrated as one such endothermic substrate in FIGS. 1 and 1A is a mass of ice, here illustrated as a multiplicity of ice cubes. Water typically freezes at 0° C. (32° F.) and, one gram of ice at 0° C. will absorb 80 calories of heat in a phase change to water at 0° C. The water so formed, will in turn continue to absorb heat at the rate of one calorie per gram until equilibrium with the environment is reached. Thus, Applicant provides an endothermic substrate ( 15 ) which may be placed inside the insulated box ( 12 ) and will absorb heat undergoing a phase change. Substrates other than ice may be used, for example: “dry ice” (CO 2 which will sublimate, or change from a solid directly to a gas), “blue-ice/gel packs” or other similar substrates. It is noted that box ( 12 ) includes walls defining air intake vents or slots ( 16 ). In the embodiment illustrated in FIGS. 1, 1 A, 1 B and 2 , it is seen that air intake slots ( 16 ) are incorporated into lid ( 14 ) of box. However, other walls of the box including the side walls may be used to define air intake slots (see for example FIG. 6 ). The function of the air intake slots ( 16 ) is to provide a means for air outside of the container to enter the container. See FIG. 6A for use of a quarter cylinder door ( 59 ) for use in conjunction with lid and slots 16 . Here door ( 59 ) includes hinges ( 59 A) on which door member ( 59 B) hangs, which optionally may have a weight ( 59 C) to help it maintain vertical or closed position when the blower motor ( 30 ) is off. Typically, endothermic substrate ( 15 ) is supported within the interior of the insulated container or box ( 12 ) through the use of a frame ( 18 ). For example, with reference to FIGS. 1, 1 A, and 3 , it is seen that frame ( 18 ) is made up of a number of components. These include duct work/support legs ( 20 ) and a number of grid platforms here, upper and lower grid platforms ( 22 ) and ( 24 ), respectively. It is seen that frame ( 18 ) comprises an assembly that can support grid platforms ( 22 ) and ( 24 ) bearing an endothermic substrate ( 15 ) while allowing air to pass through, and, in the embodiment illustrated in these figures, also incorporates duct work engageable with the insulated container ( 12 ) to guide air entering the container through the air intake slot ( 16 ) (see FIGS. 1 and 1 A). Different types of frames may be used to hold the endothermic substrate ( 15 ) within the box ( 12 ). Typically, a frame will provide the longest possible path for contact between the air and the substrate ( 15 ). Turning now to FIG. 3 for further details of the frame, it is seen that duct work/support legs ( 20 ) include depending members ( 20 A) for holding and maintaining the grid platforms ( 22 / 24 ) above the bottom surface of the interior of the container. The depending leg members ( 20 A) also have an opening therebetween defining a primary intake vent ( 20 B) through which intake air may circulate (see FIG. 1 ). It is seen with reference to FIGS. 1A and 3 that frame ( 18 ) also defines a secondary intake vent ( 20 C). This is an opening through which air may move as seen in FIG. 1A when water (from the melted ice) blocks the primary intake vent ( 20 B). The secondary intake vent ( 20 C) is controlled by a secondary intake valve ( 26 ) which is mounted on valve mounting stubs ( 20 D) so as to hang vertically under the weight of gravity against the inner walls of duct work/support legs ( 20 ). It is seen then that if the air pressure is lowered inside of the frame such as would be the case if the air were evacuated from the interior space of the frame (as seen in FIG. 1 A), the secondary intake valve ( 26 ) will move inward or away from the walls of the duct work/support legs ( 20 ) (assuming no ice is blocking this movement). Finally, it is seen that walls of duct work/support legs ( 20 ) also define grid platform support stubs ( 20 E). These will engage a portion of the grid platforms ( 22 / 24 ) to support the grid platforms above the floor of the interior of the box or container ( 12 ). A blower ( 29 ) is provided for engagement with the box ( 12 ) to remove air from the interior of the box as seen in FIGS. 1 and 1A. Blower ( 29 ) may consist of a blower motor ( 30 ) such as an electrical powered motor, the motor ( 30 ) attached to a blower prop or fan ( 32 ). The blower ( 29 ) may be attached to the box ( 12 ) at any point, but illustrated here is the incorporation of the blower to a portion of the lid which contains a lid cutout ( 31 ) here shown with a protective screen ( 31 A). The blower fan ( 32 ) is positioned in the plane of lid cutout ( 31 ) and with motor ( 30 ) engaged, it is seen that blower ( 29 ) will evacuate air from the interior of the box ( 12 ) out a blower duct ( 34 ) into one or more cool air distribution ducts ( 40 ) (see FIG. 2 ). Note that blower motor ( 30 ) is typically provided with aircraft electrical system interface or connector ( 38 ) which in turn is connected to the blower motor ( 30 ) to one or more blower motor leads ( 36 ). Aircraft electrical system interface ( 38 ) may be a commercial off the shelf unit which is designed to engage a cigarette lighter as an electrical energy source port or any auxiliary energy source port of the aircraft electrical system. Blower motor ( 30 ) is typically supported in the blower duct ( 34 ), centrally located and axially aligned therewith via the use of blower motor mount slots ( 35 ) (see FIG. 4 ). Note with reference to FIGS. 1B and 2 that cool air distribution ducts ( 40 ) may include cool air duct elbows ( 42 ), cool air outlet nozzles ( 44 ), and cool air directional adjusters ( 46 ). Both the cool air duct elbows ( 42 ) and outlet nozzles ( 44 ) are also designed to physically adjust both vertically and horizontally to the user needs. Specifically cool air duct elbows ( 42 ) enables a user to position outlet nozzles ( 44 ) by rotating the air duct elbows ( 42 ) on its axis to direct air flow. Outlet nozzles ( 44 ) are designed to be raised and lowered on a vertical axis to also direct air flow, by using telescoping air distribution ducts ( 40 A/ 40 B) (see FIG. 2 ). Both embodiments are designed to allow the heat reduction system ( 10 ) to remain functional while positioning the outlet nozzle ( 44 ). The cool air ducting system may be either spiral wound tubing or made from high density polyethylene plastic (HDPE) or any other suitable material. Turning now to the interior of the box or container ( 12 ), it seen that ice or other endothermic substrate ( 15 ) may be provided on one or more of the elevated grid platforms ( 22 ) and ( 24 ). Turning to FIG. 1, for example, ice is provided on both platforms, the upper and the lower, and with ice on the lower platform when the motor ( 30 ) is energized and air is directed through the air intake slots ( 16 ) and through the primary intake vent ( 20 B), it will go through the openings in the grid platform around the ice and cool as it moves through the ice in both platforms and out the motor duct. Therefore, it is seen that the interior of the box of a preferred embodiment illustrated in FIGS. 1, 1 A, 1 B, 2 and 3 may be categorized into three sections or zones, a warm air zone ( 28 A) which represents the zone or location in the interior of the warm air coming in from outside of the box ( 12 ) before striking any ice. A second zone is a transition zone ( 28 C) where warm air is in the process of being cooled. For example, in FIG. 1, the transition zone is located from the bottom of the lower grid ( 24 ) to the top of the ice on the upper grid ( 22 ). This air is actively being cooled as opposed to being below (or downstream) or above (or upstream) the ice. The third zone within the chamber is cool air zone ( 28 B) which is above or upstream of the last of the ice or other endothermic substrate ( 15 ). Note that as heat is absorbed by the phase change occurring in the melting of the ice, the warmest air will be first striking the ice on the lower grid ( 24 ). As the ice melts, water will drip to the bottom of the box ( 12 ) and will rise to a point where it may occlude primary intake vent ( 20 B) (see FIG. 1 A). With the motor ( 30 ) running, this will allow secondary intake valve ( 26 ) to open and air to flow through secondary intake vent ( 20 C). This air will then proceed through the ice or other endothermic substrate ( 15 ) located on the upper grid platform ( 24 ) and be exhausted out of the interior of the box ( 12 ) through motor duct ( 34 ). The arrangement and number of the grids and air intakes within the interior of the box ( 12 ) may be several. The function, however, is to provide for the passage of air from vents or slots ( 16 ) into the interior and across or adjacent an endothermic substrate ( 15 ) such that there may be a heat exchange between the endothermic substrate absorbing heat (and typically undergoing a phase change) and the air adjacent the endothermic substrate ( 15 ) losing heat (cooling off) as it moves through the box and, eventually leaves through duct work or other arrangements. Turning now, for example, to FIG. 5, it is seen that in lieu of frame ( 18 ) there may be a drop-in box ( 48 ) which will fit within the interior of box ( 12 ), which drop-in box ( 48 ) includes walls ( 48 A) and at the bottom thereof lower intake vents ( 50 ). The drop-in box ( 48 ) also includes between walls ( 48 A) substrate support members ( 52 ) upon which may be placed an appropriate endothermic substrate ( 15 ) for elevation above lower intake vents ( 50 ). However, with the lower intake vents ( 50 ) in the position illustrated in FIG. 5, this embodiment would typically provide for an endothermic substrate ( 15 ) which is self-contained and does not drip to leave a liquid phase at the bottom of the box ( 12 ) so as to occlude or block lower intake vents ( 50 ). Such substrates may include dry ice or blue ice gel packs. With the blue ice gel pack, when the liquid contained therein undergoes a phase change from solid to liquid, it will not drip to the bottom of the box ( 12 ) because it is contained in a pouch or other membrane. Dry ice on the other hand, will sublimate directly from the solid phase to the gaseous phase. FIG. 6 illustrates an alternate preferred embodiment of Applicant's heat reduction system ( 10 A). This embodiment has, in place of or in addition to the air intake slot ( 16 ) (see FIG. 1) located in or as part of lid ( 14 ), side air intake slots ( 16 A) (upper) and/or ( 16 B) (lower). If the endothermic substrate ( 15 ) to be used is one which does not release the liquid for accumulation in the bottom of the box ( 12 ), then the lower air intake slots ( 16 B) may be used and frame ( 18 ), of whatever configuration, or drop-in box ( 48 ) will hold or maintain the endothermic substrate ( 15 ) above or upstream of the lower slots. On the other hand, upper slots ( 16 A) represent a preferred alternative to slots ( 16 ) which are found in the lid ( 14 ). However, if upper slots ( 16 A) are to be used, then it is typical that a liquid forming endothermic substrate ( 15 ) will be used which will accumulate a liquid in the bottom of the box ( 12 ). Moreover, if upper slots ( 16 A) are used, then it is likely that there is either flue or duct work inside of the box ( 12 ) that will direct air entering upper slots ( 16 A) down to or near the bottom of the box ( 12 ) and vents to allow the same air to go up and through the endothermic substrate ( 15 ). FIG. 6 also illustrates the use of a drain ( 54 ). A drain is an accessory feature that will allow a liquid accumulating on or near the bottom of the lid to be drained. An additional optional feature illustrated in FIG. 6 are handles ( 56 ) or tie-down points ( 56 A) which may be provided on one or more sides of the exterior of the box ( 12 ) for convenience in handling and carrying the unit or securing the unit in a vehicle. FIG. 6 illustrates the flaps ( 57 ) which may be used with the side air intake slots ( 16 A) and/or ( 16 B) as set forth in FIG. 6 . Flaps ( 57 ) include wall member ( 57 A) for sealing off the slot when the motor ( 30 ) is not energized. The wall member ( 57 A) pivots on a pair of hinge ends ( 57 B) mounted on the interior wall of the cabinet just above the top of the side wall mounted intake slots to allow the flaps ( 57 ) to hang vertically and close slot when the motor ( 30 ) is off. While the air intake slots ( 16 A) and ( 16 B) may be left open, a flap ( 57 ) is desirable in order to minimize exposure of the air outside the box ( 12 ) to the endothermic substrate ( 15 ) when the unit is not in operation. Note that the lid ( 14 ) located air intake slots ( 16 ) (see FIG. 1) may also have a variation of the flap ( 57 ), namely one that may be normally closed via spring loaded, hydraulic or even electric means, in conjunction with the motor ( 30 ) such that when the motor ( 30 ) is running the flap ( 57 ) is at least partially open. See FIG. 6A for use of a quarter cylinder door ( 59 ) for use in conjunction with lid and slots 16 . Here door ( 59 ) includes hinges ( 59 A) on which door member ( 59 B) hangs, which optionally may have a weight ( 59 C) to help it maintain vertical or closed position when the blower motor ( 30 ) is off. The gravity mounted flaps, of course, can respond to the change in pressure between the outside of the box ( 12 ) and the inside that is created when the motor ( 30 ) is energized by opening. Applicant's unit is powered by a blower motor ( 30 ). This motor is attached to a high speed fan or prop ( 32 ) which is responsible for sucking outside air through vents, then substrate and blowing out the resulting cool air through the ducting system to cool the user or cabin air mass. Each heat reduction unit typically has at least one motor, but, depending on the size of the unit's substrate mass and the heating requirements, may have multiple motors. These motors may be mounted in the lid (see FIG. 7 ), but other mounting locations on and off the box ( 12 ) may be used. Applicant's blower motor ( 30 ) may be electrical, either AC or DC. Pneumatic motors are also possible. AC motors may be 110 volts, 220 volts or other available AC voltage. DC motors may be 6 volts, 12 volts, 24 volts, 28 volts or any workable voltage, depending upon the power availability in the environment in which it is used. Pressures for a pneumatic or hydraulic motor will also depend on availability by may be available from a duct mounted on the aircraft exterior. The motor is sized to deliver sufficient air flow through the endothermic substrate sufficient to cool the user or intended target. For example, Applicant has tested 3″-inch 12 volt or a 24 volt DC motor capable of delivering 140 standard cubic feet per minute and a 4″-inch 12 volt or 24 volt DC motor capable of delivering 245 standard cubic feet per minute which it both proved satisfactory. In an alternate preferred embodiment, Applicant provides a multiplicity of individual motors either mounted in the lid, (see FIG. 7) or at the outlet end of the duct work (see FIGS. 11 and 14 ). With such an embodiment, each user may have a switch to turn on his or her motor and a rheostat or other fan motor speed control device to control the velocity of the air through the duct. The motor still functions the same, however, sucking air through the intake slots past a substrate and through duct work to be directed at a user or intended target. FIG. 7 illustrates a system of duct work comprising spiral wound tubes ( 58 ) which attach to the blower duct ( 34 ) and may include splitter T's ( 60 ) for splitting the airflow between a number of branches ( 58 A, 58 B, 58 C or 58 D). At the removed end of the spiral wound tubes are typically provided cool air outlet nozzles ( 44 ) that may or may not include directional adjuster ( 46 ). In the embodiment illustrated in FIG. 7, attached to the tubes ( 58 ) at or near the removed and thereof is a flat positioning member ( 62 ) that is intended to extend, part way across a seat as illustrated such that an occupant may sit with the positioning member between his body and the seat and therefore maintain a position adjacent the seat with the nozzle directed anywhere (see FIG. 13 B), as for example across the occupant's crotch, abdomen, torso and even face if the user so desires. FIG. 8 illustrates variable outlet valve ( 64 ) with a selector switch ( 64 A) with a control knob ( 66 ) incorporated therewith that may direct air between either one or both of a pair of cool air outlets ports ( 68 A) and ( 68 B). The selector switch may be mounted to the end of the spiral wound tube or tubing ( 58 ). FIG. 9 illustrates Applicant's heat reduction system ( 10 ) being used in the cabin of a light aircraft. The cool air outlet nozzle ( 44 ) is pointed at the seated pilot's head and shoulders to provide relief thereto. The unit is placed in the seat next to the pilot and strapped in with the aircraft's seatbelt system. FIG. 10 illustrates a unit having an anti-backflow valve ( 69 ) situated adjacent to blower motor ( 29 ). The purpose of the anti-backflow valve ( 69 ) is such that when one or more of a multiplicity of motors (see FIG. 7) are not in use while the rest are operating, the anti-backflow valve prevents air from flowing backward through that motor's duct to bypass the substrate and go out to the unit uncooled. Anti-backflow valve ( 69 ) has flap ( 71 ) that will normally lay across blower motor outlet ( 73 ) when the motor ( 30 A) is not running. In this position, air cannot be secluded through out ( 73 ) when another motor is running, yet when motor ( 30 A) is turned on, flap ( 71 ) will allow cool air to the ductwork downstream. Note anti-backflow valve ( 69 ) will work even with one motor, if the motor is off, to prevent warm air from entering the box through the motor duct. FIG. 11 illustrates a floor mounted cooler unit ( 10 C) with housing ( 77 ) that is similar to the earlier embodiment except that each outlet nozzle has its own blower motor and fan 30 B, 30 C, 30 D, 30 E. Each motor typically has its own on/off switch ( 73 A, B, C and D) and rheostat ( 75 A, B, C and D) to control the motor speed. These motors may run off the electrical system of the vehicle or will be provided with their own power such as a battery (not shown). This embodiment typically does not use an endothermic substrate. FIG. 11A shows that housing ( 77 ) of the cooling unit ( 10 C) illustrated in FIG. 11 may include a plenum chamber ( 79 ) with an HEPA filter ( 81 ) filtering the air coming from outside container ( 77 ) through the plenum and out into the tubing ( 83 ). The unit should be set on the floor where typically the coolest air in the enclosure will be located, and the container may be used without a cooling substrate. The unit may be used for keeping surgeons cool in the operating room of a hospital. FIG. 11B illustrates a variation of Applicant's alternate preferred cooling device ( 10 D) illustrated in FIGS. 11 and 11A. In this unit, the remote individually operated motors, ( 30 B-E) draw air through container ( 77 ) which has a pair of plenums ( 79 A) and ( 79 B), both drawing filtered air from the room or cabin with a mixing slide ( 85 ) in the wall of the unit for mixing air coming from the two plenums. In one of the plenums is mounted a standard commercial off-the-shelf refrigeration or cooling coil ( 83 ) of an air conditioning or cooling unit. While plenum ( 79 A) pulls uncooled air in through the filter, the other ( 79 B), has air passing the cooling coil ( 83 ) as it goes to the user. Each motor is connected to the tube which connects to the slides ( 85 ) or mixing valves allowing individual settings based on a desired percentage of cooled and noncooled air. This mixing combined with the rheostat control of the air velocity allows a number of individual users to adjust their microenvironment to their own individual comfort level. Applicant also provides herein, with reference to FIG. 12, yet another use of an invention related to cooling devices of the type anticipated herein or of any other type that will provide cool airflow through a cool air duct ( 72 ). The embodiment of the invention set forth in FIG. 12 provides for a cool air duct ( 72 ) to be attached between an article of clothing ( 70 ) of an individual, such as a shirt, wherein the outlet or mouth ( 74 ) of the cool air duct is inserted between the body of the individual and the shirt or other article of clothing ( 70 ). Applicant refers to this new invention as microenvironment cooling and is intended to provide cool air in that layer of air immediately adjacent the skin of the user. It is that layer of air that requires cooling and, where cooling capacity of a unit providing the cooling is limited, it is important that this air boundary immediately adjacent the skin of the user is cooled. It is important in microenvironmental cooling to cool the air layer directly adjacent the skin as compared to an entire airmass in which an occupant is located. There are a number of places in which microenvironment cooling may be effective. These include the cabin of an aircraft or other vehicle and the operating room in a hospital, where often a surgeon (see FIG. 15) must work under hot lights. In FIGS. 13A, 14 and 15 , Applicant illustrates the use of custom designed microenvironmental nozzles ( 80 ) for insertion beneath an article of clothing ( 70 ). FIG. 14 provides one such custom nozzle ( 80 ) which nozzle includes a belt hook ( 82 ) for engagement with a belt of the user as well as, optionally, a blower ( 29 A) with blower motor and fan incorporated within the nozzle ( 80 ). Note that this nozzle ( 80 ) also includes a tongue ( 84 ) which tongue may be used to keep the clothing such as the shirt off the skin of the user and provide a ready path for the cool air coming out of the outlet ( 86 ) of nozzle ( 80 ). FIG. 15 . Illustrates applicants heat reduction system 10 including cool air distribution ducts ( 40 ) used with a custom nozzle ( 80 ) and custom designed shirt ( 70 A) wherein the nozzle and shirt are positively engaged to one another as by elastic ( 81 ) or stitching or any other means. FIG. 16 illustrates another aspect of Applicant's invention which may be used by a firefighter. In this aspect of the invention, Applicant provides a metallized protective suit ( 90 ) which covers the entirety of the body of the user, such as a firefighter. The firefighter wears an oxygen mask ( 92 ) and oxygen bottle ( 94 ) beneath the suit ( 90 ). There is a dry ice pack ( 96 ) within the suit with a blower motor ( 98 ) to circulate air around the dry ice ( 100 ) which is located within the container ( 102 ) of the dry ice pack ( 96 ). There are pressure differential releasing valves ( 104 ) that may be located at the neck, wrist or ankles to keep pressure in the suit constant and prevent it from overblowing as well as for keeping a constant flow of fire suppressing gas, such as CO 2 , emanating around the firefighter. Although the invention has been described with reference to specific embodiments, this description is not meant to be construed in a limited sense. Various modifications of the disclosed embodiments, as well as alternative embodiments of the inventions will become apparent to persons skilled in the art upon the reference to the description of the invention. It is, therefore, contemplated that the appended claims will cover such modifications that fall within the scope of the invention.

4y

BACKGROUND This invention relates to a hip rafter to corner plate connection; most commonly occurring in wood frame buildings having a stick-framed roof of either dimensional lumber or plywood I-rafters. The invention may be used in traditional hip roofs which is one of the four basic roof shapes, or it may be used in roofs which are a combination of the basic shapes. A hip is defined as the outside corner where two planes of a roof meet. It is comprised of a hip rafter at the corner and jack rafters from the hip to the eave. The hip rafter is supported at its lower end by the wall at plate level (or by a post) and at its upper end by the ridge (or by a wall). Sheet metal connectors for joining common rafters to wood top plate members have been in use for some time and come in many different configurations. There is, however, only one commercially available connector known to applicant for joining hip rafters to corner plates and it was granted to Tyrell T. Gilb Aug. 17, 1993 for Rafter-to-Corner Plate Connection, U.S. Pat. No. 5,236,273. The Gilb connector, however, if used in a building with a right angled corner requires that the corner of the wood lower corner plate and the wood top plate be bevel cut. In addition, the Gilb connector gives minimal lateral support to prevent overturning to the hip rafter. A further limitation of Gilb is that the connector cannot be installed after the hip rafter has been nailed to the top plates. The rafter-to-corner plate connectors taught by a few patents, none of which are known to be commercially available, are considered impractical because they are either too costly to manufacture or are incapable of handling the many different rafter slope angles. The current practice of many roofing contractors is to use a Simpson hurricane tie or twist strap and flatten the 90 degree bend to a 45 degree bend to accommodate the rafter. This practice is costly because of the additional labor cost in bending the metal on the job and does not provide an architecturally aesthetic solution. SUMMARY OF THE INVENTION The hip corner plate of the present invention is economical to manufacture and easy to install. The hip corner plate of the present invention may be installed after the hip is in place and requires no bevel cuts of the corner plates. The hip corner plate of the present invention can accommodate various roof pitches without modification of the connector and is able to resist high uplift loads for all pitches. In addition to resisting uplift loads, the hip corner plate acts as a gusset plate in strengthening the corner of the structure, and provides lateral stability to the hip rafter. A further advantage is the fact that the hip corner plate can be attached to both top plates with a minimum amount of fasteners in the end grain. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of the hip corner plate connector of the present invention. FIG. 2 is a perspective view of the hip corner plate connector illustrated in FIG. 1 installed in a typical corner intersection on dual top plates of a building using stick frame construction. FIG. 3 is top plan view of the hip corner plate connector illustrated in FIGS. 1 and 2 with the corner intersection and portions of the top plates and hip rafter in phantom line. FIG. 4 is a left side elevation view of the hip corner plate taken along line 4--4 of FIG. 3 with portions of the hip rafter and top plates in phantom line. FIG. 5 is a front elevation view of the hip corner plate connector taken along line 5--5 of FIG. 4. FIG. 6 is a right side elevation view of the hip corner plate connector taken along line 6--6 of FIG. 3. FIG. 7 is a top plan view of the sheet metal blank of a hip corner plate connector as illustrated in FIG. 1 and typically used to connect a single 2x hip rafter. FIG. 8 is a top plan view of a modified sheet metal blank of a hip corner plate connector of the type illustrated in FIG. 1, but typically used to connect a dual 2 x hip rafter. DESCRIPTION OF THE INVENTION The hip corner plate connection 1 of the present invention in a building structure consists of hip rafter 2 having a bottom edge 3, a top edge 4 and generally parallel first and second side faces 5 and 6; a first lower plate member 7 having a lower face 8, a generally parallel upper face 9, inner and outer side edges 10 and 11, and an end face 12; a first top plate member 13 having, a first lower face 14 in registration with a portion of the upper face 9 of the first lower plate member 7, a top face 15, inner and outer side edges 16 and 17, and an end face 18; a second lower plate member 19 having a lower face 20, a generally parallel upper face 21, inner and outer side edges 22 and 23, and an end face 24 abutting a portion of the inner side edge 10 of the first lower plate member 7; a second top plate member 25 having, a first lower face 26 in registration with a portion of the upper face 21 of the second lower plate member 19, a top face 27, inner and outer side edges 28 and 29 and an end face 30; a single element sheet metal hip corner plate connector 31 having: a first base member 32 including a lower portion 33 in close registration with a portion of the outer side edge 11 of the first lower plate member 7, a mid portion 34 in close registration with a portion of the end face 30 of the second top plate member 25, and an upper portion 35, a first hip rafter flange 36 integrally connected to the upper portion 35 of the first base member 32 extending at an angle 42 thereto, and dimensioned and positioned for registration with a portion of the first side face 5 of the hip rafter 2, a second base member 37 integrally connected to the first base member 32 at a generally right angle including a lower portion 38 in close registration with a portion of the end face 12 of the first lower plate member 7, a midportion 39 in close registration with a portion of the outer side edge 29 of the second top plate member 25, and an upper portion 40, a second hip rafter flange 41 integrally connected to the upper portion 40 of the second base member 37 extending at an angle 43 thereto in generally parallel relation to the first hip rafter flange 36, and dimensioned and positioned for registration with a portion of the second side face 6 of the hip rafter 2, and a seat edge 44 formed in the hip corner plate connector 31 extending between the first and second hip rafter flanges 36 and 41 and dimensioned and positioned for receiving a portion of the bottom edge 3 of the hip rafter 2; first fastener means 45 penetrating the lower portion 33 of the first base member 32 and the outer side edge 11 of the first lower plate member 7; second fastener means 46 penetrating the mid portion 34 of the first base member 32 and the end face 30 of the second top plate member 25; third fastener means 47 penetrating the first hip rafter flange 36 and the hip rafter 2; fourth fastener means 48 penetrating the lower portion 38 of the second base member 37 and the end face 12 of the first lower corner plate member 7; fifth fastener means 49 penetrating the midportion 39 of the second base member 37 and the outer side edge 29 of the second top plate member 25; and sixth fastener means 50 penetrating the second hip rafter flange 41 and the hip rafter 2. In another form of the invention where the first and second top plate members 13 and 25 rest directly upon the top ends of studs and upon a corner post instead of upon a lower plate member, the hip corner plate connection 1 in a building structure consists of: a hip rafter 2 having a bottom edge 3, a top edge 4 and generally parallel first and second side faces 5 and 6; support means 51 having first and second upper faces 52 and 53, and first and second outer side faces 54 and 55; a first top plate member 13 having a first lower face 14 in registration with a portion of the first upper face 52 of the support means 51, a top face 15, inner and outer side edges 16 and 17, and an end edge 18; a second top plate member 25 having, a first lower face 26 in registration with a portion of the second upper face 53 of the support means 51, a top face 27, inner and outer side edges 28 and 29 and an end face 30; a single element sheet metal hip corner plate connector 31 having: a first base member 32 including a lower portion 33 in close registration with a portion of the first outer side face 54 of the support means 51, a midportion 34 in close registration with a portion of the end face 30 of the second top plate member 25, and an upper portion 35, a first hip rafter flange 2 integrally connected to the upper portion 35 of the first base member 32 extending at an angle 42 thereto, and dimensioned and positioned for registration with a portion of the first side face 5 of the hip rafter 2, a second base member 37 integrally connected to the first base member 32 at a generally right angle including a lower portion 38 in close registration with a portion of the second outer side face 55 of the support means 51, a mid portion 39 in close registration with a portion of the outer side edge 29 of the second top plate member 25, and an upper portion 40, a second hip rafter flange 41 integrally connected to the upper portion 40 of the second base member 37 extending at an angle 43 thereto in generally parallel relation to the first hip rafter flange 36, and dimensioned and positioned for registration with a portion of the second side face 6 of the hip rafter 2, and a seat edge 44 formed in the hip corner plate connector 31 extending between the first and second hip rafter flanges 36 and 41 and dimensioned and positioned for receiving a portion of the bottom edge 3 of the hip rafter 2; first fastener means 45 penetrating the lower portion 33 of the first base member 32 and the first outer side face 54 of the support means 51; second fastener means 46 penetrating the mid portion 34 of the first base member 32 and the end face 30 of the second top plate member 25; third fastener means 47 penetrating the first hip rafter flange 36 and the hip rafter 2; fourth fastener means 48 penetrating the lower portion 38 of the second base member 37 and the second outer side face 55 of the support means 51; fifth fastener means 49 penetrating the midportion 39 of the second base member 37 and the outer side edge 29 of the second top plate member 25; and sixth fastener means 50 penetrating the second hip rafter flange 41 and the hip rafter 2. Preferably, the seat edge 44 is formed in the hip corner plate connector 31 by means of a first generally straight edge 56 formed in the first base member 32 and a second generally straight edge 57 formed in the second base member in the same plane and intersecting the first generally straight edge 56. The hip corner plate connector 31 is constructed so that it is not necessary to "bird mouth" the hip rafter 2; i.e. cut a notch in the lower side. However, if it is necessary to "bird mouth" the hip rafter 2, the hip corner plate connector 31 can still accommodate such a rafter. In addition, the first and second hip rafter flanges 36 and 41 are preferably bent to form obtuse angles 42 and 43 with the upper portions 35 and 40 of the first and second base members 32 and 37 respectively. To assist in the installation, fastener openings 58 may be formed in the sheet metal hip corner plate connector 31 for receiving the first through sixth fastener means 45-50. As a further aid in installing the hip corner plate connector, indicia means 59 may be marked on the hip corner plate connector 31 indicating an alignment plane with the first lower faces 14 and 26 of the first and second top plate members 13 and 25. Another form of the invention is illustrated in FIG. 8. The hip corner plate connector 31' illustrated in FIG. 8 is used to connect dual 2 x hip rafters in a hip corner plate connection and is identical in construction and function to the hip corner plate connector illustrated in FIGS. 1-7 except for increases in dimensions and number of nail openings. Like parts have been given identical numbers and are distinguished only by the addition of a prime mark ('). Since the construction and function of the hip corner plate connector 31' is identical to the hip corner plate connector 31 previously described, in the interest of brevity, no further description is believed necessary. As an example, the hip corner plate may be made of 18 gauge galvanized metal. The hip corner plate as illustrated in FIGS. 1-7 and used to connect a single hip rafter 2 to first lower plate 7, second lower plate member 19, first top plate member 13, and second top plate member 25 is code rated to withstand uplift loads of 665 pounds and lateral loads of 400 pounds. The hip corner plate as illustrated in FIG. 8 and used for dual hip rafters has a code rating of 1000 pounds in uplift and 450 pounds of lateral load. As may be seen from the illustrations, lateral support for the hip rafter 2 is provided by upper portion 35 of first base member 32 and upper portion 40 of second base member 37. There is no set way of installing the hip corner plate connector 31. A method preferred by many builders is to temporarily attach the hip rafter 2 to the ridge member and to the first and second top plate members 13 and 25 and then insert the hip corner plate connector 31 from beneath the hip rafter 2 so that the indicia means 59 lines up with the first lower faces of first and second top plate members 13 and 25. Fastener means 45, 46, 48 and 49 are then driven so that the hip corner plate connector 31 is secured to the first lower plate member 7, first top plate member 13, second lower plate member 19, and second top plate member 25. Next, third fastener means 47 are inserted through openings 58 in first hip rafter flange 36 into hip rafter 2. Finally, sixth fastener means 50 are driven through openings 58 in second hip rafter flange 41 into hip rafter 2. Fabrication of the hip corner plate connect 31 is preferably from a flat sheet metal blank as illustrated in FIGS. 7 and 8. First, the blank is cut in the shape generally illustrated and cuts are made in the blank to form the seat edge 44. Another cut is made along line 60 to form the first and second hip rafter flanges 36 and 41. A 90° bend is then made along line 61 to form the intersection of first and second base members 32 and 37. Finally, 45° bends are made along bend lines 62 and 63 upwardly as illustrated in FIGS. 7 and 8 to place first and second hip rafter flanges 36 and 41 in the proper position for receipt of hip rafter 2.

4y

BACKGROUND OF THE INVENTION 1. Field of the Invention This invention generally relates to a bicycle hub dynamo assembly is configured with a hub and a releasable electrical connector. 2. Background Information Bicycling is becoming an increasingly more popular form of recreation as well as a means of transportation. Moreover, bicycling has become a very popular competitive sport for both amateurs and professionals. Whether the bicycle is used for recreation, transportation or competition, the bicycle industry is constantly improving the various components of the bicycle as well as the frame of the bicycle. Recently, bicycles have been equipped with more and more electrical components requiring electrical power. Thus, some bicycles have been equipped with a hub dynamo for generating and supplying electrical power to the various electrical components such as lamps, cycle computers, electronic shifting units, etc. Two examples of hub dynamos are disclosed in U.S. Pat. Nos. 6,409,197 and 6,559,564, which are assigned to Shimano, Inc. The dynamo hub typically has an electrical cord that supplies the power to the various components mounted on the bicycle that require electrical power. This electrical cord must be attached to the bicycle frame in a manner such that it does not interfere with the normal operation of the bicycle and its components. For example, when the dynamo hub is part of a front hub, the electrical cord must be mounted in a manner such that it does not interfere with the turning of the front fork and front bicycle wheel relative to the main frame. Moreover, if a dynamo hub were to be mounted on a bicycle having a front suspension fork, then the electrical cord must be mounted in a manner to provide for the contraction and expansion of the front suspension fork. Also, when a dynamo hub is integrated with a hub that has a quick release axle, the connection between the electrical cord and the dynamo hub sometimes gets damaged due to the fragile connection therebetween. In other words, when the wheel with the dynamo hub is detach from the main frame, it is usually necessary to detach the electrical cord from the dynamo hub to remove the wheel. This often results in the connection between the electrical cord and the dynamo hub being damaged over a period of time in which the connection is repeatedly connected and disconnected. In view of the above, it will be apparent to those skilled in the art from this disclosure that there exists a need for an improved hub dynamo assembly. This invention addresses this need in the art as well as other needs, which will become apparent to those skilled in the art from this disclosure. SUMMARY OF THE INVENTION One object of the present invention is to provide an electrical connector for use with a hub dynamo assembly that can be repeatedly disconnected and reconnected to a dynamo hub without being damaged. Another object of the present invention is to provide an electrical connector for use with a hub dynamo assembly that is relatively inexpensive to manufacture. The foregoing objects can basically be attained by providing a bicycle hub dynamo assembly that basically comprises a hub axle, a hub shell, a bearing unit, a generator mechanism and an electrical cord. The hub axle has a first axle end and a second axle end with a center axis extending between the first and second axle ends. The hub shell has a first shell end and a second shell end with an inner tubular surface forming a central passage extending between the first and second shell ends, the hub axle being disposed within the central passage of the hub shell. The bearing unit is disposed between the hub axle and the hub shell to rotatably support the first shell end of the hub shell on the first axle end of the hub axle. The generator mechanism is housed in the hub shell and adapted to generate electricity by rotation of the hub shell relative to the hub axle. The generator mechanism includes a first electrical connector with first electrical contacts. The electrical cord includes a second electrical connector with second electrical contacts configured to mate with the first electrical contacts of the first electrical connector, the second electrical connector includes an inner housing part and an outer housing part with a fixing portion of the second electrical contacts retained between the inner and outer housing parts. These and other objects, features, aspects and advantages of the present invention will become apparent to those skilled in the art from the following detailed description, which, taken in conjunction with the annexed drawings, discloses a preferred embodiment of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS Referring now to the attached drawings which form a part of this original disclosure: FIG. 1 is a partial, side elevational view of a bicycle with a front bicycle suspension assembly and a front bicycle hub dynamo assembly that utilize a bicycle electrical cord for powering a bicycle lamp in accordance with a preferred embodiment of the present invention; FIG. 2 is a front elevational view of the front suspension fork which includes the front bicycle suspension assembly and the front bicycle hub dynamo assembly for powering the bicycle lamp via the bicycle electrical cord having the bicycle electrical cord connector in accordance with the present invention; FIG. 3 is a first side elevational view of the front suspension fork in accordance with the present invention with the bicycle lamp and other parts removed for purposes of illustration; FIG. 4 is a second side elevational view of the front suspension fork in accordance with the present invention with the bicycle lamp and other parts removed for purposes of illustration; FIG. 5 is a rear elevational view of the front suspension fork in accordance with the present invention with the bicycle lamp and other parts removed for purposes of illustration; FIG. 6 is a partial side elevational view of a bottom portion of the front suspension fork with the electrical connector of the electrical cord disconnected in accordance with the present invention; FIG. 7 is a partial enlarged side elevational view of a bottom portion of the front suspension fork in accordance with the present invention; FIG. 8 is a partial top plan view of a top portion of the front suspension fork in accordance with the present invention; FIG. 9 is a partial top plan view of the top portion of the front suspension fork in accordance with the present invention with the top cover removed; FIG. 10 is an inside plan view of the top cover of the front suspension fork with the switch unit mounted thereto in accordance with the present invention; FIG. 11 is a partial cross-sectional view of the top portion of the top cover, the upper crown and one of the inner tubes in accordance with the present invention; FIG. 12 is a partial perspective view of the bottom of the outer tube with the electrical extending outwardly therefrom; FIG. 13 is a rear elevational view of the front hub with the top half shown in cross section in accordance with the present invention; FIG. 14 is a partial perspective view of the lower or bottom end of the electrical cord with the electrical cord connector in accordance with the present invention; FIG. 15 is an end elevational view of the electrical cord connector of the electrical cord in accordance with the present invention; FIG. 16 is a partial exploded perspective view of the electrical cord connector with the outer housing part disconnected from the inner housing part in accordance with the present invention; FIG. 17 is a cross sectional view of the electrical connector as seen along section line 17 — 17 of FIG. 15 in accordance with the present invention; FIG. 18 is a cross sectional view of the electrical connector as seen along section line 18 — 18 of FIG. 15 in accordance with the present invention; FIG. 19 is a cross sectional view of the electrical connector, similar to FIG. 18 , but coupled to the electrical connector of the hub dynamo in accordance with the present invention; FIG. 20 is a top plan view of the outer housing part of the electrical cord connector in accordance with the present invention; FIG. 21 is a first edge elevational view of the outer housing part of the electrical cord connector in accordance with the present invention; FIG. 22 is a side elevational view of the outer housing part of the electrical cord connector in accordance with the present invention; FIG. 23 is a second edge elevational view of the outer housing part of the electrical cord connector in accordance with the present invention; FIG. 24 is a bottom plan view of the outer housing part of the electrical cord connector in accordance with the present invention; FIG. 25 is a first cross-sectional view of the outer housing part of the electrical cord connector as seen along section line 25 — 25 of FIG. 22 in accordance with the present invention; FIG. 26 is a second cross-sectional view of the outer housing part of the electrical cord connector as seen along section line 26 — 26 of FIG. 21 in accordance with the present invention; FIG. 27 is a third cross-sectional view of the outer housing part of the electrical cord connector as seen along section line 27 — 27 of FIG. 21 in accordance with the present invention; FIG. 28 is a top plan view of the inner housing part of the electrical cord connector in accordance with the present invention; FIG. 29 is a first edge elevational view of the inner housing part of the electrical cord connector in accordance with the present invention; FIG. 30 is a first side elevational view of the inner housing part of the electrical cord connector in accordance with the present invention; FIG. 31 is a second edge elevational view of the inner housing part of the electrical cord connector in accordance with the present invention; FIG. 32 is a bottom plan view of the inner housing part of the electrical cord connector in accordance with the present invention; FIG. 33 is a second side elevational view of the inner housing part of the electrical cord connector in accordance with the present invention; FIG. 34 is a first cross-sectional view of the inner housing part of the electrical cord connector as seen along section line 34 — 34 of FIG. 31 in accordance with the present invention; FIG. 35 is a second cross-sectional view of the inner housing part of the electrical cord connector as seen along section line 35 — 35 of FIG. 29 in accordance with the present invention; FIG. 36 is a third cross-sectional view of the inner housing part of the electrical cord connector as seen along section line 36 — 36 of FIG. 30 in accordance with the present invention; FIG. 37 is first side elevational view of one of the electrical contacts for the electrical cord connector in accordance with the present invention; FIG. 38 is an edge elevational view of one of the electrical contacts of the electrical cord connector in accordance with the present invention; and FIG. 39 is a second side elevational view of one of the electrical contacts of the electrical cord connector in accordance with the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Selected embodiments of the present invention will now be explained with reference to the drawings. It will be apparent to those skilled in the art from this disclosure that the following descriptions of the embodiments of the present invention are provided for illustration only and not for the purpose of limiting the invention as defined by the appended claims and their equivalents. Referring initially to FIGS. 1–7 , a front portion of a bicycle 10 is illustrated that is equipped with a front suspension fork 12 and a front dynamo hub 14 in accordance with a first embodiment of the present invention. A bicycle electrical cord 16 is installed in the front suspension fork 12 for interconnecting at least two electrical components. Preferably, the bicycle electrical cord 16 is connected to the front dynamo hub 14 (one electrical component) by an electrical cord connector 18 for powering a bicycle lamp 20 (another electrical component) in accordance with a first embodiment of the present invention. As seen in FIG. 1 , the front portion of the bicycle 10 has an upper end of the front suspension fork 12 movably coupled to a main bicycle frame 22 and a lower end of the front suspension fork 12 coupled to the front dynamo hub 14 . The front dynamo hub 14 is part of a front wheel 26 , which is rotatably mounted to the front suspension fork 12 by the front dynamo hub 14 in conventional manner. A handlebar 28 is fixed to the front suspension fork 12 in a conventional manner to turn the front suspension fork 12 relative to the main bicycle frame 22 . The bicycle electrical cord 16 is arranged to extend through an internal area of the front suspension fork 12 as explained below. In the illustrated embodiment, as best seen in FIGS. 2 and 6 – 7 , the bicycle electrical cord 16 has a first cord portion 16 a and a second cord portion 16 b with a switch unit 30 electrically coupled between the first and second cord portions 16 a and 16 b . The first cord portion 16 a has a lower end electrically coupled to the front dynamo hub 14 via the electrical cord connector 18 and an upper end electrically coupled to the switch unit 30 . The second cord portion 16 b has one end electrically coupled to the lamp 20 and the other end electrically coupled to the switch unit 30 . The switch unit 30 is mounted on the top of a portion of the front suspension fork 12 as discussed below. The switch unit 30 is used to connect and disconnect electrical power electrically from the front dynamo hub 14 to the bicycle lamp 20 . The front suspension fork 12 basically includes a pair of telescoping struts 31 and 32 that are interconnected by an upper crown 33 which is coupled to a steerer tube 34 . The steerer tube 34 is coupled to the main bicycle frame 22 in a conventional manner and has the handlebar 28 coupled to its upper end in a conventional manner. As explained below, the basic constructions of the struts 31 and 32 are identical, except that the strut 31 is configured and arranged to act as a shock absorber and the strut 32 is configured and arranged to act as a protective conduit for protecting the first cord portion of the electrical cord 16 . As best seen in FIGS. 2 , 4 and 5 , the strut 31 includes an inner (upper) telescoping member or tube 36 and an outer (lower) telescoping member or tube 38 telescopically coupled to the inner telescoping tube 36 . The inner and outer telescoping tubes 36 and 38 are constructed of hard rigid materials that are conventionally used for struts. The inner and outer telescoping tubes 36 and 38 of the strut 31 are configured and arranged to form a variable volume chamber having a dampening unit 40 located therein. The dampening unit 40 is configured and arranged to absorb impacts on the front suspension fork 12 due to engagement with a rock, a hole, a bump or a like. The dampening unit 40 can be any conventional dampening unit such as one or more compression springs, a combination of dampening elements and/or the like. Accordingly, the dampening unit 40 will not be discussed or illustrated in detail herein. Basically, the inner telescoping tube 36 includes an upper end portion 36 a and a lower end portion 36 b with an upper internal passage 36 c located between the upper and lower end portions 36 a and 36 b . The outer telescoping tube 38 includes an upper end portion 38 a , a lower end portion 38 b and a lower internal passage 38 c located between the upper and lower end portions 38 a and 38 b . The internal passages 36 c and 38 c form the variable volume chamber with the dampening unit 40 located therein. The upper end portion 36 a of the inner telescoping tube 36 is fixedly coupled to the upper crown 33 , while the lower end portion 36 b of the inner telescoping tube 36 is slideably coupled within the upper end portion 38 a of the outer telescoping tube 38 . A seal (not shown) is configured and arranged in a conventional manner between the lower end portion 36 b of the inner telescoping tube 36 and the upper end portion 38 a of the outer telescoping tube 38 to allow for the relative sliding movement of the inner and outer telescoping tubes 36 and 38 . The upper end portion 36 a of the inner telescoping tube 36 also has internal treads that adjustably secures an adjustment member 49 . The adjustment member seals the opening of the upper end portion 36 a of the inner telescoping tube 36 . Thus, the variable volume chamber of the strut 31 is a closed chamber. The outer telescoping tube 38 includes an upper end portion 38 a , a lower end portion 38 b and a lower internal passage 38 c located between the upper and lower end portions 38 a and 38 b . The lower end portion 38 b has a wheel mount or dropout 38 d for attaching one end of the front dynamo hub 14 thereto. As best seen in FIGS. 2 , 3 and 5 , the strut 31 contract and expand together with the dampening unit 40 to act as a shock absorber for the entire structure of the front suspension fork 12 . More specifically, a telescoping motion occurs between the inner and outer tubes 36 and 38 to compress the dampening unit 40 , which is configured and arranged within the inner and outer tubes 36 and 38 to absorb impacts on the front suspension fork 12 due to engagement with a rock, a hole, a bump or a like. In other words, as the telescoping strut 31 is compressed to absorb a shock, the lower end portion 36 b of the inner telescoping tube 36 travels towards the lower end portion 38 b of the outer telescoping tube 38 , thus reducing the volume of the variable volume chamber formed between the inner and outer telescoping tubes 36 and 38 . Similarly, when the telescoping strut 31 expands to return to its neutral position, the lower end portion 36 a of the inner telescoping tube 36 travels away from the lower end portion 38 b of the outer telescoping tube 38 to increase the volume of the variable volume chamber formed by the inner and outer telescoping tubes 36 and 38 . Preferably, the strut 32 does not include a dampening unit, but rather has the first cord portion 16 a of the electrical cord 16 running therethrough. Of course, if needed and/or desired, a second dampening unit can be installed in the strut 32 that does not interfere with the electrical cord 16 . The strut 32 basically includes an inner (upper) telescoping member or tube 46 and an outer (lower) telescoping member or tube 48 telescopically coupled to the inner telescoping tube 46 . The inner and outer telescoping tubes 46 and 48 are constructed of hard rigid materials that are conventionally used for struts. The inner and outer telescoping tubes 46 and 48 of the strut 32 are configured and arranged to form a variable volume chamber having a majority of the first cord portion 16 a of the electrical cord 16 located therein. The outer telescoping tubes 38 and 48 are interconnected by a bridge member 50 that is integrally formed with the outer telescoping tubes 38 and 48 . Of course, it will be apparent to those skilled in the art that the bridge member 50 can be a separate member that is fixed to the outer telescoping tubes 38 and 48 . Thus, the bridge member 50 interconnects the struts 31 and 32 together such that they act as a single unit. In other words, the struts 31 and 32 contract and expand together with the dampening unit 40 acting as a shock absorber for the entire structure of the front suspension fork 12 . More specifically, a telescoping motion occurs between the inner tubes 36 and 46 and the outer tubes 38 and 48 to compress the dampening unit 40 . Accordingly, the dampening unit 40 is configured and arranged to absorb impacts on the front suspension fork 12 due to engagement with a rock, a hole, a bump or a like. Basically, the inner telescoping tube 46 includes an open upper end portion 46 a and an open lower end portion 46 b with an upper internal passage 46 c located between the upper and lower end portions 46 a and 46 b . The outer telescoping tube 48 includes an upper end portion 48 a , a lower end portion 48 b and a lower internal passage 48 c located between the upper and lower end portions 48 a and 48 b . The internal passages 46 c and 48 c form an enclosed chamber with the first cord portion 16 a of the electrical cord 16 extending therethrough. The first cord portion 16 a of the electrical cord 16 is configured and arranged within the internal passages 46 c and 48 c of the telescoping tubes 46 and 48 such that sufficient slack is provided in the first cord portion 16 a to accommodate expansion and contraction of the inner and outer telescoping tubes 46 and 48 . The upper end portion 46 a of the inner telescoping tube 46 is fixedly coupled to the upper crown 33 , while the lower end portion 46 b of the inner telescoping tube 46 is slideably coupled within the upper end portion 48 a of the outer telescoping tube 48 . The inner telescoping tube 46 is open at its upper end such that an upper end portion of the first cord portion 16 a of the electrical cord 16 extends outwardly therefrom for connection with the switch unit 30 as seen in FIG. 11 . A seal (not shown) is provided between the lower end portion 46 b of the inner telescoping tube 46 and the upper end portion 48 a of the outer telescoping tube 48 in a conventional manner to allow the relative sliding movement of the inner and outer telescoping tubes 46 and 48 . The outer telescoping tube 48 includes an upper end portion 48 a , a lower end portion 48 b and a lower internal passage 48 c located between the upper and lower end portions 48 a and 48 b . The lower end portion 48 b has a wheel mount or dropout 48 d for attaching one end of the front dynamo hub 14 thereto. Also as best seen in FIG. 12 , the outer telescoping tube 48 is provided with a cord opening 48 e at its lower end such that a lower end portion of the first cord portion 16 a of the electrical cord 16 extends outwardly from the lower internal passage 48 c of the outer telescoping tube 48 . Referring now to FIGS. 8–11 , the upper crown 33 includes a top cover 52 that is fixedly coupled thereto for covering the upper open end of the inner telescoping tube 46 . Preferably, the top cover 52 is secured to the upper crown 33 by a fastener such as a screw 53 that threads into an internally threaded hole 54 formed in the upper crown 33 . Thus, the top cover 52 is configured and arranged to be selectively removed from a position covering the upper end opening of the inner telescoping tube 46 for accessing the switch unit 30 . The switch unit 30 is preferably fixedly coupled to the top cover 52 . The switch unit 30 includes a push button switch 55 that projects outwardly from an upper surface of the top cover 52 and an electrical connector 56 protruding downwardly from an inner surface of the top cover 52 . Preferably, the electrical connector 56 of the switch unit 30 projects into partially into the upper end portion 46 a of the inner telescoping tube 46 . The electrical connector 56 is electrically coupled to the electrical cord 16 that is connected between the front dynamo hub 14 and the bicycle lamp 20 . The push button switch 55 is a conventional switch that is selectively pushed to connect and disconnect a pair of electrical contacts (not shown) in the electrical connector 56 . In other words, electrical power to the lamp 20 is interrupted by pushing the push button switch 55 when the push button switch 55 is in the contact closed position that supplies electrical power to the lamp 20 . The push button switch 55 is pushed again to disconnect electrical power to the lamp 20 when the push button switch 55 is in the contact open position that interrupts electrical power to the lamp 20 . Referring now to FIGS. 1–3 , 5 , 6 , 7 , 10 – 12 and 16 – 19 , the electrical cord 16 is a conventional electrical cord with a pair of insulated conductor wires W 1 and W 2 having an outer elastomeric cover or sheath C. In the area of the switch unit 30 , the elastomeric cover or sheath C of the electrical cord 16 is split into two pieces that define the first and second cord portions 16 a and 16 b. As best seen in FIGS. 1–3 , the first cord portion 16 a of the electrical cord 16 is located in the internal passages 46 c and 48 c of the inner and outer telescoping tubes 46 and 48 , and is arranged with sufficient slack to accommodate expansion and contraction of the inner and outer telescoping tubes 46 and 48 . Thus, the first cord portion 16 a of the electrical cord 16 is protected and does not interfere with the normal operation of the bicycle 10 and its components. As seen in FIGS. 5–7 and 16 – 19 , the lower ends of the conductor wires W 1 and W 2 are electrically coupled to the electrical connector 18 as discussed below. The upper ends of the conductor wires W 1 and W 2 are electrically coupled to the lamp 20 using conventional push clips (not shown). The conductor wire W 1 is split into two pieces with the switch unit 30 electrically coupling the two pieces of conductor wire W 1 together. In particular, the electrical contacts (not shown) in the electrical connector 56 are connected to the two pieces of the conductor wire W 1 . Referring now to FIG. 13 , the front dynamo hub 14 is preferably a substantially conventional member, except for its electrical connector 60 . Thus, the front dynamo hub 14 will not be discussed or illustrated in detail herein. As seen in FIGS. 6 , 7 and 19 , the electrical connector 60 has an insulating body portion 60 a and a pair of electrical contacts 60 b that are electrically coupled to a dynamo portion of the front dynamo hub 14 in a conventional manner. The insulating body portion 60 a supports the electrical contacts 60 b in a protected manner for coupling with the electrical connector 18 as seen in FIG. 19 . The electrical connector 60 is configured and arranged as a male connector. Basically, the front dynamo hub 14 comprises an internal stator assembly 61 and an external rotor assembly 62 that form the dynamo portion of the front dynamo hub 14 . The internal stator assembly 61 comprises a hub axle 63 , a pair of stator yokes 64 , a bobbin 65 with a wound coil 66 , a cylindrical core yoke 67 and two separate disks 68 . The internal stator assembly 61 is fixed to the front suspension fork 12 by the hub axle 63 . The hub axle 63 is preferably a quick release hub axle having an adjustment nut 63 a coupled to one end and a cam lever 63 b coupled to the other end. The electrical connector 60 , the stator yokes 64 , the cylindrical core yoke 67 and the separation disks 68 are all fixed to this hub axle 63 so they do not rotate with the wheel 26 . The external rotor assembly 62 comprises a pair of frame portions 69 and a cap 70 integrated as shown in FIG. 13 . The external rotor assembly 62 is rotatably fixed to the hub axle 63 with the aid of bearings B. The flanges formed on the outer peripheral portion of the frame portions 69 are attached to a plurality of spokes 26 a of the front wheel 26 . A permanent magnet M comprising four magnets spaced at equal intervals in the circumferential direction is fixed to the cap 70 . In this permanent magnet M, the north (N) and south (S) poles are intermittently formed at equally spaced intervals. A total of twenty-eight poles of each type face the stator yokes 64 . The operation of the front dynamo hub 14 is explained in more detail in U.S. Pat. No. 6,409,197 (assigned to Shimano, Inc.). Referring now to FIGS. 14–19 , the electrical connector 18 is configured and arranged as a female connector. The electrical cord connector 18 includes an outer housing part 71 , an inner housing part 72 and a pair of electrical contacts 73 . Preferably, each of the inner and outer housing parts 71 and 72 is constructed as a one-piece, unitary member from an insulating plastic material such that the outer and inner housing parts 71 and 72 insulate the contacts 73 from each other. Preferably, the material of the inner and outer housing parts 71 and 72 is a rigid insulating material with limited flexibility. The inner and outer housing parts 71 and 72 are connected together by a snap fit as explained below with the electrical contacts retained between abutting surfaces of the inner and outer housing parts 71 and 72 . Referring now to FIGS. 20–27 , the outer housing part 71 is preferably a one piece, unitary member that has a main body section 74 and a cord receiving section 75 that are integrally formed as a one piece, unitary member. The main body section 74 has a substantially rectangular outer cross-sectional shape with an internal space or cavity 76 that is sized to retain the inner housing part 72 therein. Thus, the main body section 74 has first end wall 81 , a first side wall 82 , a second end wall 83 and a second side wall 84 that define the rectangular cavity 76 that receives and retains the inner housing part 72 . The end wall 81 is provided with a gripping tab 81 a and a retaining opening 81 b . The end wall 83 is provided with a gripping tab 83 a and a retaining opening 83 b . Also, the interior surfaces of the end walls 81 and 83 are preferably step shaped to form two abutments 81 c and 83 c , respectively, which limit the movement of the inner housing part 72 when the inner housing part 72 is being snap fitted into the outer housing part 71 . The cord receiving section 75 has a substantially cylindrical cord receiving bore 85 that is in communication with the interior cavity 76 of the main body section 71 . The cord receiving bore 85 has a lower portion of the electrical cord 16 located therein. Preferably, the interface between the cover C of time electrical cord 16 and cord receiving bore 85 is watertight. A cord retaining ring 86 is located on the lower portion of the electrical cord 16 that is located in the interior cavity 76 of the main body section 74 to prevent the electrical cord 16 from being pulled out of the electrical connector 18 . Referring now to FIGS. 28–36 , the inner housing part 72 has a substantially rectangular overall exterior shape in cross-section that is dimensioned to be press-fitted into the interior cavity 76 of the outer housing part 71 by a snap fit. In particular, the inner housing part 72 has a first end wall 91 , a first side wall 92 , a second end wall 93 and a second side wall 94 that are sized slightly smaller than the interior cavity 76 of the outer housing part 71 . Theses walls define a connector receiving recess or cavity 90 that is dimensioned to frictionally retain the connector 60 of the front dynamo hub 14 therein. The end wall 91 includes a retaining protrusion 95 that is a generally triangularly shaped member that include an abutment surface 95 a extending perpendicular to the end wall 91 and a ramp surface 95 b that is inclined to the end wall 91 . The end wall 93 includes a retaining protrusion 96 that is a generally triangularly shaped member that include an abutment surface 96 a extending perpendicular to the end wall 91 and a ramp surface 96 b that is inclined to the end wall 93 . The ramp surfaces 95 b and 96 b are designed to allow easier insertion of the inner housing part 72 into the internal cavity 76 of the outer housing part 71 . When the inner housing part 72 is inserted into the outer housing part 71 , the protrusions 95 and 96 are received in the retaining openings 81 b and 83 b of the outer housing part 71 . Preferably, the protrusions 95 and 96 are attached in a cantilevered fashion to the end walls 91 and 93 such that the protrusions 95 and 96 are resiliently coupled to the end walls 91 and 93 to flex inwardly relative to the longitudinal axis of the inner housing part 72 when the inner housing part 72 is inserted into the interior cavity 76 of the outer housing part 71 . The side wall 92 has a pair of contact receiving grooves 97 and a pair of through openings 98 . The contact receiving grooves 97 are configured and arranged to tightly receive the electrical contacts 73 therein. The through openings 98 are configured and arranged in the side wall 92 along center portions of the contact receiving grooves 97 . These openings 98 allow the electrical contacts 73 to be deformed for fixedly securing the electrical contacts 72 to the inner housing barn 72 as discussed below. Referring now to FIGS. 16–19 and 37 – 39 , the electrical contacts 73 are preferably identical. Thus, each of the contacts 73 has a wire connection end 73 a and an electrical contact end 73 b with a center section or fixing portion 73 c extending between the wire connection end 73 a and the electrical contact end 73 b . Preferably, the electrical contacts 73 are constructed as a one-piece, unitary member from a metallic sheet material having good electrical conductive characteristics. The wire connection end 73 a is provided with a hole for receiving one of the conductors of the conductor wires W 1 and W 2 that is preferably soldered thereto. The connection end 73 a is also preferably provided with a reduced section so that the connection end 73 a can be deformed or bent out of the initial plane of a center section 73 c of the contact 73 of as shown in FIG. 17 . The contact end 73 b is preferably part-shaped such that the free end of the contact end 73 b is cantilevered to be resiliently deflected towards the center section 73 c of the contact 73 when the electrical connector 18 is connected to the electrical connector 60 of the front dynamo hub 14 as seen in FIG. 19 . In particular, when the contacts 73 are slide into the contact receiving grooves 97 of the inner housing part 72 , the contact ends 73 b extend around a front edge of the side wall 92 and then the free end of the contact ends 73 b extend rearwardly into the interior cavity 76 of the inner housing part 72 . The portions of the contact ends 73 b located in the interior cavity 76 of the inner housing part 72 are spaced from the interior surface of the side wall 92 of the inner housing part 72 . This arrangement allows the contact ends 73 b to be resiliently deflected towards the interior surface of the side wall 92 of the inner housing part 72 when the electrical connector 18 is connected to the electrical connector 60 of the front dynamo hub 14 as seen in FIG. 19 . Each electrical contact 73 is also provided with a cutout 73 d in the center section or fixing portion 73 c to form a retaining tab 73 e . The retaining tabs 73 e are designed to be bent or deformed into the openings 98 of the side wall 92 of the inner housing part 72 to secure the contacts 73 to the inner housing part 72 prior to the inner housing part 72 being coupled to the outer housing part 71 . The bicycle lamp 18 is a conventional bicycle lamp. Thus, bicycle lamp 18 will not be discussed or illustrated in detail herein. However, the bicycle lamp 18 is powered by the electrical energy generated by the front dynamo hub 14 . The bicycle 10 and its various components are well known in the prior art, except for those components that relate to the present invention. Thus, the bicycle 10 and its various components will not be discussed or illustrated in detail herein, except for those components that relate to the present invention. As used herein, the following directional terms “forward, rearward, above, downward, vertical, horizontal, below and transverse” as well as any other similar directional terms refer to those directions of a bicycle equipped with the present invention. Accordingly, these terms, as utilized to describe the present invention should be interpreted relative to a bicycle equipped with the present invention. The terms of degree such as “substantially”, “about” and “approximately” as used herein mean a reasonable amount of deviation of the modified term such that the end result is not significantly changed. These terms should be construed as including a deviation of at least ±5% of the modified term if this deviation would not negate the meaning of the word it modifies. While only selected embodiments have been chosen to illustrate the present invention, it will be apparent to those skilled in the art from this disclosure that various changes and modifications can be made herein without departing from the scope of the invention as defined in the appended claims. Furthermore, the foregoing descriptions of the embodiments according to the present invention are provided for illustration only, and not for the purpose of limiting the invention as defined by the appended claims and their equivalents.

4y

REFERENCE TO RELATED APPLICATIONS The present application claims priority to U.S. Provisional application No. 60/343,851, filed on Dec. 28, 2001, the entire content of which is incorporated by reference herein. FIELD OF THE INVENTION This invention is in the field of proteomics, and applies mass spectrometry to the analysis of peptides and amino acids. More particularly, the invention relates to a mass spectrometry-based method for detection of amino acid phosphorylation. BACKGROUND TO THE INVENTION With the availability of a burgeoning sequence databases, genomic applications demand faster and more efficient methods for the global screening of protein expression in cells. However, the complexity of the cellular proteome expands substantially if protein post-translational modifications are also taken into account. Dynamic post-translational modification of proteins is important for maintaining and regulating protein structure and function. Among the several hundred different types of post-translational modifications characterized to date, protein phosphorylation plays a prominent role. Enzyme-catalyzed phosphorylation and de-phosphorylation of proteins is a key regulatory event in the living cell. Complex biological processes such as cell cycle, cell growth, cell differentiation and cell metabolism are orchestrated and tightly controlled by reversible phosphorylation events which modulate protein activity, stability, interaction and localization. Perturbations in phosphorylation states of proteins, e.g. by mutations which generate constitutively active or inactive protein kinases and phosphatases, play a prominent role in oncogenesis. Comprehensive analysis and identification of phosphoproteins, combined with exact localization of phosphorylation sites in those proteins (‘phosphoproteomics’) is a prerequisite for understanding complex biological systems and the molecular features leading to disease. It is estimated that ⅓ of all proteins present in a mammalian cell are phosphorylated and that kinases, enzymes responsible for that phosphorylation, constitute about 1–3% of the expressed genome. Organisms use reversible phosphorylation of proteins to control many cellular processes including signal transduction, gene expression, the cell cycle, cytoskeletal regulation and apoptosis. A phosphate group can modify serine, threonine, tyrosine, histidine, arginine, lysine, cysteine, glutamic acid and aspartic acid residues. However, the phosphorylation of hydroxyl groups at serine (90%), threonine (10%), or tyrosine (0.05%) residues are the most prevalent, and are involved, along with other processes, in metabolism, cell division, cell growth, and cell differentiation. Because of the central role of phosphorylation in the regulation of life, much effort has been focused on the development of methods for characterizing protein phosphorylation. The identification of phosphorylation sites on a protein is complicated by the facts that proteins are often only partially phosphorylated and that they are often present only at very low levels. Therefore techniques for identifying phosphorylation sites should preferably work in the low picomole to sub-picomole range. Traditional methods for analyzing O-phosphorylation sites involve incorporation of 32 P into cellular proteins via treatment with radiolabeled ATP. The radioactive proteins can be detected during subsequent fractionation procedures (e.g. two-dimensional gel electrophoresis or high-performance liquid chromatography [HPLC]). Proteins thus identified can be subjected to complete hydrolysis and the phospho-amino acid content determined. The site(s) of phosphorylation can be determined by proteolytic digestion of the radiolabeled protein, separation and detection of phosphorylated peptides (e.g. by two-dimensional peptide mapping), followed by peptide sequencing by Edman degradation. These techniques can be tedious, require significant quantities of the phosphorylated protein and involve the use of considerable amounts of radioactivity. In recent years, mass spectrometry (MS) has become an increasingly viable alternative to more traditional methods of phosphorylation analysis. The most widely used method for selectively enriching phosphopeptides from mixtures is immobilized metal affinity chromatography (IMAC). In this technique, metal ions, usually Fe3+ or Ga3+, are bound to a chelating support. Phosphopeptides are selectively bound because of the affinity of the metal ions for the phosphate moiety. The phosphopeptides can be released using high pH or phosphate buffer, the latter usually requiring a further desalting step before MS analysis. Limitations of this approach include possible loss of phosphopeptides due to their inability to bind to the IMAC column, difficulty in the elution of some multiply-phosphorylated peptides, and background from unphosphorylated peptides (typically acidic in nature) which also have some affinity for immobilized metal ions. Two types of chelating resin are commercially available, one using iminodiacetic acid and the other using nitrilotriacetic acid. Some groups have observed that iminodiacetic acid resin is less specific than nitrilotriacetic acid, whereas another study reported little difference between the two. Several studies have examined off-line MS analysis of IMAC-separated peptides. Recently, two groups have described protocols to achieve this goal. Oda et al. ( Nat Biotechnol. 2001 19:379–82) start with a protein mixture in which cysteine reactivity is removed by oxidation with performic acid. Base hydrolysis is used to induce -elimination of phosphate from phosphoserine and phosphothreonine, followed by addition of ethanedithiol to the alkene. The resulting free sulflhydryls are coupled to biotin, allowing purification of phosphoproteins by avidin affinity chromatography. Following elution of phosphoproteins and proteolysis, enrichment of phosphopeptides is carried out by a second round of avidin purification. Disadvantages of this approach include the failure to detect phosphotyrosine containing peptides and the generation of diastereoisomers in the derivatization step. The approach suggested by Zhou et al. ( Nat Biotechnol 2001 19:375–378) circumvents these problems but involves a six step derivatization/purification protocol for tryptic peptides which requires more than 13 hrs to complete and affords only a 20% yield from picomoles of phosphopeptide starting material. The method begins with a proteolytic digest which has been reduced and alkylated to eliminate reactivity from cysteine residues. Following N-terminal and C-terminal protection, phosphoramidate adducts at phosphorylated residues are formed by carbodiimide condensation with cystamine. The free sulfhydryl groups produced from this step are covalently captured onto glass beads coupled to iodoacetic acid. Elution with trifluoroacetic acid then regenerates phosphopeptides for analysis by mass spectrometry. SUMMARY OF THE INVENTION One aspect of the present invention provides a method for identifying phosphorylated amino acids within a protein by combining affinity purification and mass spectroscopy. In general, the subject method makes use of affinity capture reagents for isolating, from a protein sample, those proteins which have been phosphorylated. In order to improve the selectivity/efficiency of the affinity purification step, the protein samples to be analyzed are chemically modified at one or more of the C-terminal carboxyl or amino acid side chains of the proteins which may interfere with the selectively of the affinity purification step—for example, the side chains of glutamic acid and aspartic acid residues can be converted to neutral derivatives such as by alkyl-esters. Phosphorylated proteins which are isolated are then analyzed by mass spectroscopy in order to identify patterns of phosphorylation across a proteome, and/or to provide the identity of proteins in the sample which are phosphorylated or to show changes in phosphorylation status between two different samples. In certain preferred embodiments, the proteins are cleaved into smaller peptide fragments before, after or during the chemical modification step. For instance, the proteins can be fragmented by enzymatic hydrolysis to produce peptide fragments having carboxy-terminal lysine or arginine residues. In certain preferred embodiments, the proteins are fragmented by treatment with trypsin. In certain embodiments, the proteins are mass-modified with isotopic labels before, after or during the chemical modification step. In certain embodiments, the proteins are further separated by reverse phase chromatography before analysis by mass spectroscopy. There are a variety of mass spectroscopy techniques which can be employed in the subject method. In certain preferred embodiments, the isolated proteins are identified from analysis using tandem mass spectroscopy techniques, such as LC/MS/MS (Liquid Chromatography tandem Mass Spectrometry). Where the proteins have been further fragmented with trypsin or other predictable enzymes, the molecular weight of a fragment, as determined from the mass spectroscopy data, can be used to identify possible matches in databases indexed by predicted molecular weights of protein fragments which would result under similar conditions as those generated in the subject method. However, the subject method can also be carried out using mass spectroscopy techniques which produce amino acid sequence mass spectra for the isolated proteins or peptide fragments. The sequence data can be used to search one or more sequence databases. The subject method is amenable to analysis of multiple different protein samples, particularly in a multiplex fashion. In such embodiments, the proteins or fragments thereof are isotopically labeled in a manner which permits discrimination of mass spectroscopy data between protein samples. That is, mass spectra on the mixture of various protein samples can be deconvoluted to determine the sample origin of each signal observed in the spectra. In certain embodiments, this technique can be used to quantitate differences in phosphorylation levels between samples prepared under different conditions and admixed prior to MS analysis. In certain embodiments, the subject method is used for analyzing a phosphoproteome. For example, the proteins in the sample can be chemically modified at glutamic acid and aspartic acid residues, such as by alkyl-esterification, to generate neutral side chains at those positions. The phosphorylated proteins in the sample are then isolated by immobilized metal affinity chromatography and analyzed by mass spectroscopy. In preferred embodiments, the proteins are cleaved, e.g., by trypsin digestion or the like, into smaller peptide fragments before, after or during the step of chemically modify the glutamic acid and aspartic acid residues. In one embodiment, the subject method is carried out on multiple different protein samples, and proteins which are differentially phosphorylated between two or more protein samples are identified. That data can, for instance, be used to generate or augment databases with the identity of proteins which are determined to be phosphorylated. Another aspect of the invention provides a method for identifying a treatment which modulates the phosphorylation of an amino acid in a target polypeptide. In general, this method is carried out by providing a protein sample which has been subjected to a treatment of interest, such as with ectopic agents (drugs, growth factors, etc.). The protein samples can also be derived from normal cells in different states of differentiation or tissue fate, or derived from normal and diseased cells. Following the affinity purification/MS method set forth above, the identity of proteins which have been phosphorylated in the treated protein sample relative to an untreated sample or control sample can determined. From this identification step, one can determine whether the treatment results in a pattern of changes in phosphorylation, relative to the untreated sample or control sample, which meet a pre-selected criteria. Thus, one can use this method to identify compounds likely to mimic the effect of a growth factor by scoring for similarities in phosphorylation patterns when comparing proteins from the compound-treated cells with proteins from the growth factor treated cells. The treatment of interest can include contacting the cell with such compounds as growth factors, cytokines, hormones, or small chemical molecules. In certain embodiments, the method is carried out with various members of a chemically diverse library. Yet another aspect of the present invention provides a method of conducting a drug discovery business. Using the assay described above, one determines the identity of a compound which produces a pattern of changes in phosphorylation, relative to the untreated sample or control sample, which meet a pre-selected criteria. Therapeutic profiling of the compound identified by the assay, or further analogs thereof, can be carried out to determine efficacy and toxicity in animals. Compounds identified as having an acceptable therapeutic profile can then be formulated as part of a pharmaceutical preparation. In certain embodiments, the method can include the additional step of establishing a distribution system for distributing the pharmaceutical preparation for sale, and may optionally include establishing a sales group for marketing the pharmaceutical preparation. In other embodiments, rather than carry out the profiling and/or formulation steps, one can license, to a third party, the rights for further drug development of compounds which are discovered by the subject assay to alter the level of phosphorylation of the target polypeptide. Yet another aspect of the present invention provides a method of conducting a drug discovery business in which, after determining the identity of a protein which is phosphorylated under the conditions of interest, the identity of one or more enzymes which catalyze the phosphorylation is determined. Those enzyme(s) are then used as targets in drug screening assays for identifying compounds which inhibit or potentiate the enzymes and which, therefore, can modulate the phosphorylation of the identified protein under the conditions of interest. REFERENCE TO THE DRAWINGS FIG. 1 . Shows the results obtained from analyses of a phosphopeptide sample by immobilized metal affinity chromatography (IMAC) and nanoflow high-performance liquid chromatography (HPLC) on an liquid chromatography electrospray (LCQ) ion trap mass spectrometer. Five non-phosphorylated proteins; glyceraldehyde 3-phosphate dehydrogenase, bovine serum albumin, carbonic anhydrase, ubiquitin, and β-lactoglobulin (Sigma Chemical Co., St. Louis, Mo.) (100 nmol each) in 1.1 ml of 100 mM ammonium bicarbonate (pH 8) were digested with trypsin (20 μg) (Promega, Madison, Wis.) for 24 h at 37° C. The reaction was quenched with 65 μl of glacial acetic acid, and the mixture diluted to a final volume of 50 ml with 0.1% acetic acid. To this solution was added 500 pmol of HPLC (High Performance Liquid Chromatography) purified phosphopeptide, DRVpYIHPF (SEQ ID NO: 1, Novabiochem, San Diego, Calif.) in 0.1% acetic acid (2 μL of a 250 pmol/μL stock solution). An aliquot of the standard mixture (100 μl) was lyophilized and redissolved in 100 μl of 2 N methanolic HCl. This latter solution was prepared by dropwise addition of 160 μl of acetyl chloride, with stirring, to 1 ml of methanol. Esterification was allowed to proceed for 2 h at room temperature. Solvent was removed by lyophylization and the resulting sample re-dissolved in 100 μl of solution containing equal volumes of methanol, water and acetonitrile. Phosphate methyl esters are not observed under these conditions. Mass spectra recorded by a combination of immobilized metal affinity chromatography (IMAC) and nano-flow HPLC microelectrospray ionization mass spectrometry on the phosphopeptide, DRVpYIHPF (SEQ ID NO: 1), present at the level of 10 fmol/μl in a mixture containing tryptic peptides from 5 proteins at the level of 2 pmol/μl. Aliquots corresponding to 0.5 μl of the above solutions (tryptic peptides from 1 pmol of each protein plus 5 fmol of phosphopeptide, DRVpYIHPF, SEQ ID NO: 1) were analyzed by mass spectrometry. (A) Selected ion chromatogram, SIC, or plot of the ion current vs. scan number for m/z 564.5 corresponding to the (M+2H) ++ of the phosphopeptide, DRVpYIHPF (SEQ ID NO: 1). (B) MS/MS spectrum characteristic of the sequence, DRVpYIHPF (SEQ ID NO: 1), recorded on ions of m/z 564.5 in scans 610–616. (C) Electrospray ionization mass spectrum recorded during this same time interval. Abundant ions from tryptic peptides non-specifically bound to the IMAC column obscure the signal at m/z 564.5 for DRVpYIHPF (SEQ ID NO: 1). (D) SIC for m/z 578.5 corresponding to the (M+2H)++ ion for the dimethyl ester of DRVpYIHPF (SEQ ID NO: 1). (E) MS/MS spectrum characteristic of the sequence, DRVpYIHPF (SEQ ID NO: 1), recorded in on ions of m/z 578.5 in scans 151–163. (F) Electrospray ionization mass spectrum recorded in scan 154 showing the parent ion, m/z 578.5 for the phosphopeptide dimethyl ester and the absence of signals for tryptic peptides non specifically bound to the IMAC column. FIG. 2 . Shows the result (top) of phosphopeptide β-casein analyzed by extracted ion chromatography from the HPLC separation, showing the β-casein peak at 30.71 min, and result (bottom) of the phosphopeptide β-casein analyzed by MS/MS scan at m/z=1031.5, showing individual peptide fragments of said phosphopeptide. DETAILED DESCRIPTION OF THE INVENTION The current progression from genomics to proteomics is fueled by the realization that many properties of proteins (e.g., interactions, post-translational modifications) cannot be predicted from a DNA sequence. The present invention provides a method useful to identify phosphorylated amino acid sites within peptide analytes. In certain preferred embodiments, the subject method is used to identify phosphate modified serine, threonine, tyrosine, histidine, arginine, lysine, cysteine, glutamic acid and aspartic acid residues, more preferably to identify phosphoserine-, phosphothreonine- and phosphotyrosine-containing peptides. Unlike the prior art methods, which require conversion of the modified amino acid residue to another chemical entity which can be used to purify a particular peptide, the subject method is based on affinity capture by way of the originally modified amino acid residue following treatment of the pepticle with agents which modify other residues in the peptide which might otherwise interfere with the affinity capture process. Phosphopeptides bind Fe(III) with high selectivity, so are amenable to affinity purification using Fe(III)-immobilized metal-ion affinity chromatography (IMAC) techniques. However, the presence of hydroxyl and carboxyl groups in sample peptides, e.g., due to a free carboxyl terminus or the presence of acidic side chains such as glutamic acid and aspartic acid, can reduce the efficiency of purification by contributing to non-specific binding to the metal column. Conversion of these side chains to neutral derivatives, such as by alkyl-esterification (which converts Glu and Asp to their neutral, alkyl ester derivatives, and also converts the C-terminal carboxyl group to an alkyl ester) or by treatment with diazomethane (Knapp, D. R., Methods in Enzymology, 193, 1990, p314–329) can be used to reduce such non-specific binding. Phosphate groups, if present, are not neutralized under the reaction conditions and are, accordingly, still available for coordinating the metal ion. Thus, the resulting peptide mixture is contacted with a metal affinity column or resin which retains only peptides which bear the phosphate groups. The other peptides “flow through” the column. The phosphopeptides can then be eluted in a second step and analyzed by mass spectrometry, such as LC/MS/MS. Sequencing of the peptides can reveal both their identity and the site of phosphorylation. To further illustrate, alkyl esters of free carboxyl groups in a peptide can be formed by reaction with alkyl halides and salts of the carboxylic acids, in an amide-type solvent, particularly dimethylformamide, in the presence of an iodine compound. In other embodiments, the reaction can be carried out with equimolecular amounts of an alkyl halide and a tertiary aliphatic amine. In yet another embodiment, the method of the present invention can include esterification of the free carboxylic groups by reacting a salt of the carboxylic acid with a halogenated derivative of an aliphatic hydrocarbon, a cycloaliphatic hydrocarbon or an aliphatic hydrocarbon bearing a cyclic substituent in an aqueous medium, and in the presence of a phase transfer catalyst. By the expression “phase transfer catalyst” is intended a catalyst which transfers the carboxylate anion from the aqueous phase into the organic phase. The preferred catalysts for the process of the invention are the onium salts and more particularly quaternary ammonium and/or phosphonium salts. The alkyl ester of the dipeptide is most preferably a methyl ester and may also be an ethyl ester or alkyl of up to about four carbon atoms such as propyl, isopropyl, butyl or isobutyl. In still other embodiments, the carboxyl groups can be modified using reagents which are traditionally employed as carboxyl protecting groups or cross-coupling agents, such as 1,3-dicyclohexylcarbodiimide (DCC), 1,1′ carbonyldiimidazole (CDI), 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide hydrochloride (EDC), benzotriazol-1-yl-oxytris(dimethylamino) phosphonium hexafluorophosphate (BOP), and 1,3-Diisopropylcarbodiimide (DICD). In certain embodiments, the proteins or protein mixtures are further processed, e.g., cleaved chemically or enzymatically, to reduce to the proteins to smaller peptides fragments. In a preferred embodiment, treatment with an enzyme which produces a carboxy terminal lysine and/or arginine residue, such as trypsin, Arg-C and Lys-C, or a combination thereof, is employed. This digestion step may not be necessary if the proteins are relatively small. In certain embodiments, the reactants and reaction conditions can be selected such that differential isotopic labeling can be carried out across multiple different samples to generate substantially chemically identical, but isotopically distinguishable, peptides. In this way, the source of particular samples can be encoded in the label. This technique can be used to quantitate differences in phosphorylation patterns and/or levels of phosphorylation between two or more samples. By way of illustration, the esterification reaction can be performed on one sample in the matter described above. In another sample, esterification is performed by deuterated or tritiated alkyl alcohols, e.g., D 3 COD (D 4 methyl-alcohol), leading to the incorporation of three deuterium atoms instead of hydrogen atoms for each site of esterification. Likewise, 18 O can be incorporated into peptides. The peptide mixtures from the two samples are then mixed and analyzed together, for example by LC/MS/MS. The phosphopeptides will be detected as light and heavy forms, and the relative ratio of peak intensities can be used to calculate the relative ratio of the phosphorylation in the two cases. It can also be advantageous to perform one methyl-esterification reaction on the whole protein with methyl-alcohol for both samples. Subsequent to enzymatic digestion, one of the samples is then further esterified with D4 Methyl-alcohol. This leads to the incorporation of three deuterium atoms in each peptide rather than a variable number depending on the number of acidic residues in the peptide. To complete the analysis, the sample may be further separated by reverse phase chromatography and on-line mass spectrometry analysis using both MS and MS/MS. To illustrate, the sequence of isolated peptides can be determined using tandem MS (MSn) techniques, and by application of sequence database searching techniques the protein from which the sequenced peptide originated can be identified. In general, at least one peptide sequence derived from a protein will be characteristic of that protein and be indicative of its presence in the mixture. Thus, the sequences of the peptides typically provide sufficient information to identify one or more proteins present in a mixture. Quantitative relative amounts of proteins in one or more different samples containing protein mixtures (e.g., biological fluids, cell or tissue lysates, etc.) can be determined using isotopic labeling as described above. In this method, each sample to be compared is treated with a different isotopically labeled reagent. The treated samples are then combined, preferably in equal amounts, and the proteins in the combined sample are enzymatically digested, if necessary, to generate peptides. As described above, peptides are isolated by affinity purification and analyzed by MS. The relative amounts of a given protein in each sample is determined by comparing relative abundances of the ions generated from any differentially labeled peptides originating from that protein. More specifically, the method can be applied to screen for and identify proteins which exhibit differential levels of phosphorylation in cells, tissue or biological fluids. The method of the present invention is useful for a variety of applications. For example, it permits the identification of enzyme substrates which are phosphorylated in response to different environmental cues provided to a cell. Identification of those substrates, in turn, can be used to understand the intracellular signaling pathways involved in any particular cellular response, as well as to identify the enzyme responsible for catalyzing the phosphorylation. To further illustrate, changes in phosphorylation states of substrate proteins can be used to identify kinases and/or phosphatases which are activated or inactivated in a manner dependent on particular cellular cues. In turn, those enzymes can be used as drug screening targets to find agents capable of altering their activity and, therefore, altering the response of the cell to particular environmental cues. So, for example, kinases and/or phosphatases which are activated in transformed (tumor) cells can be identified through their substrates, according to the subject method, and then used to develop anti-proliferative agents which are cytostatic or cytotoxic to the tumor cell. In other embodiments, the present method can be used to identify a treatment which can modulate the phosphorylation of an amino acid in a target protein without any knowledge of the upstream enzymes which produce the modified target protein. By comparing the level of phosphorylation before and after certain treatments, one can identify the specific treatment which leads to a desired change in the level of phosphorylation of one or more target proteins. To illustrate, one can screen a library of compounds, for example, small chemical compounds from a library, for their ability to induce or inhibit phosphorylation of a target polypeptide. In other instances, it may be desirable to screen compounds for their ability to induce or inhibit the dephosphorylation of a target polypeptide (i.e., by a phosphatase). Similar treatments are not limited to small chemical compounds. For example, a large number of known growth factors, cytokines, hormones and any other known agents known to be capable of being phosphorylated are also within the scope of the invention. In addition, treatments are not limited to chemicals. Many other environmental stimuli are also known to be able to cause phosphorylation. For example, osmotic shock may activate the p38 subfamily of MAPK (Mitogen Activated Protein Kinase) and induce the phosphorylation of a number of downstream targets. Stress, such as heat shock or cold shock, may activate the JNK/SAPK (Jun N-terminal Kinase/Stress-Activated Protein Kinase) subfamily of MAPK and induce the phosphorylation of a number of downstream targets. Other treatments such as pH change may also stimulate signaling pathways characterized by the post-translational modification of key signaling components. To illustrate, one may wish to identify the effect of treating cells with a growth factor. More specifically, one may desire to identify the specific signal transduction pathways involved downstream of a growth factor. By comparing phosphorylation levels of certain candidate polypeptides before and after the growth factor treatment, one can use the method of the instant invention to determine precisely which downstream signaling pathways of interest are activated or down regulated. This, in turn, also leads to the identification of potential drug screening targets if such signaling pathways are to be modulated. In connection with such methods, the instant invention also provides a method for conducting a drug discovery business, comprising: i) by suitable methods mentioned above, determining the identity of a compound which modulates phosphorylation of an amino acid in a target polypeptide; ii) conducting therapeutic profiling of the compound identified in step i), or further analogs thereof, for efficacy and toxicity in animals; and, iii) formulating a pharmaceutical preparation including one or more compounds identified in step ii) as having an acceptable therapeutic profile. Such business method can be further extended by including an additional step of establishing a distribution system for distributing the pharmaceutical preparation for sale, and may optionally include establishing a sales group for marketing the pharmaceutical preparation. The instant invention also provides a business method comprising: i) by suitable methods mentioned above, determining the identity of a compound which modulates phosphorylation of an amino acid in a target polypeptide; ii) licensing, to a third party, the rights for further drug development of compounds which alter the level of modification of the target polypeptide. The instant invention also provides a business method comprising: i) by suitable methods mentioned above, determining the identity of the polypeptide and the nature of the phosphorylation induced by the treatment; ii) licensing, to a third party, the rights for further drug development of compounds which alter the level of phosphorylation of the polypeptide. EXAMPLE Phosphoproteome Analysis by Mass Spectrometry Following the methodology of the present invention, it is now possible to characterize most, if not all, phosphoproteins from a whole cell lysate in a single experiment. Proteins were digested with trypsin and the resulting peptides then converted to methyl esters, enriched for phosphopeptides by immobilized metal affinity chromatography (IMAC) and analyzed by nanoflow HPLC/electrospray ionization mass spectrometry. In an initial experiment, B-casein was digested with trypsin and analyzed using the method of the invention. Results of this experiment are shown in FIG. 2 . More than a 1,000 phosphopeptides were detected when the methodology was applied to the analysis of a whole cell lysate from S. cerevisiae . Sequences, including 383 sites of phosphorylation derived from 216 peptides, were determined. Of these, 60 were singly phosphorylated, 145 doubly phosphorylated, and 11 triply phosphorylated. To validate the approach, these results were compared with the literature, revealing 18 previously identified sites, including the doubly phosphorylated motif pTXpY derived from the activation loop of two MAP kinases. We note that the methodology can easily be extended to display and quantitate differential expression of phosphoproteins in two different cell systems, and therefore demonstrates an approach for “phosphoprofiling” as a measure of cellular state. We prepared a standard mixture of tryptic peptides containing a single phosphopeptide and then analyzed the mixture before and after converting the peptides to the corresponding methyl esters. This rendered the IMAC selective for phosphopeptides and eliminated confounding binding through carboxylate groups. Equimolar quantities of glyceraldehyde 3-phosphate dehydrogenase, bovine serum albumin, carbonic anhydrase, ubiquitin, and β-lactoglobulin were digested with trypsin (approximately 125 predicted cleavage sites) and then combined with the phosphopeptide DRVpYIHPF (SEQ ID NO: 1, lower case p precedes a phosphorylated residue), to give a mixture which contained tryptic peptides at the 2 pmol/μl level and phosphopeptide at the 10 fmol/μl level. All experiments were performed on 0.5 μl aliquots of this solution. Shown in FIG. 1 are the results obtained when a 0.5 μl aliquot of the standard mixture was analyzed by a combination of IMAC 5,6 and nanoflow-HPLC on an LCQ ion-trap mass spectrometer. In this experiment, the instrument was set to cycle between two different scan functions every 2 sec throughout the HPLC gradient. Electrospray ionization spectra were recorded in the first of the two scans. MS/MS spectra on the (M+2H) ++ ion of the phosphopeptide, DRVpYIHPF (SEQ ID NO: 1, m/z 564.5) were recorded in the second scan of the cycle. FIG. 1A shows a selected-ion-chromatogram (SIC) or plot of the ion current observed for m/z 564.5 as a function of scan number. Note that a signal at this m/z value is observed at numerous points in the chromatogram. Only ions at m/z 564.5 in scans 610–616 fragment to generate MS/MS (tandem Mass Spectrometry) spectra characteristic of the phosphopeptide, DRVpYIHPF (SEQ ID NO: 1, FIG. 1B ). We conclude that DRVpYIHPF (SEQ ID NO: 1) elutes from the HPLC column in scans 610–616. Shown in FIG. 1C is an electrospray ionization mass spectrum recorded during this same time period. Note that the spectrum contains signals of high intensity (ion currents of 1–3×10 9 ) corresponding to non-phosphorylated tryptic peptides in the mixture but no signal above the chemical noise level for the phosphopeptide (m/z 564.5). We conclude that tryptic peptides containing multiple carboxylic acid groups can bind efficiently to the IMAC column, elute during the HPLC gradient, and suppress the signal from trace level phosphopeptides in the mixture. To prevent binding of non-phosphorylated peptides to the IMAC column, all peptides in the standard mixture were converted to the corresponding peptide methyl esters and a 0.5 μl aliquot was then analyzed by the protocol outlined above. To detect the phosphopeptide in which both carboxylic acid groups had been esterified, MS/MS spectra were recorded on the (M+2H) ++ ion at m/z 578.5. The SIC for m/z 578.5 ( FIG. 1D ) suggests that the phosphopeptide dimethyl ester elutes during scans 151–163. Indeed, MS/MS spectra ( FIG. 1E ) recorded in this time window all contain the predicted fragments expected for the dimethyl ester of DRVpYIHPF (SEQ ID NO: 1). FIG. 1F shows an electrospray ionization mass spectrum recorded in the same area of the chromatogram (scan #154). Note that the parent ion, m/z 578.5, for the phosphopeptide dimethyl ester is now observed with a signal/noise of 3/1 and an ion current of 2 ×10 7 . This signal level on the LCQ is not a typical for phosphopeptide samples at the 3–5 fmol level. Note also that signals above the chemical noise (ion current of 1×10 7 ) for non-phosphorylated tryptic peptides no longer appear in this electrospray ionization spectrum or in any other spectrum recorded throughout the entire chromatogram. We conclude that conversion of carboxylic acid groups to methyl esters reduces nonspecific binding by at least two orders of magnitude and allows detection of phosphopeptides in complex mixtures down to the level of at least 5 fmol with the LCQ instrument. To further evaluate the above protocol, we next analyzed a protein pellet (500 μg) obtained from a whole cell lysate of S. cerevisiae . If the average mol. wt. (molecular weight) of yeast proteins is 25 kDa (kilo Dalton) and half the genome is expressed and isolated in the pellet, then the average quantity each protein in the sample is expected to be approximately 5 pmol. If one makes the further assumption that 30% of expressed proteins contain at least one covalently bound phosphate, the total number of phosphoproteins in the sample could easily exceed 1,000. To evaluate this possibility the pellet was digested with trypsin and the resulting peptides converted to peptide methyl esters. One-fifth of the resulting mixture was then fractionated by IMAC and analyzed by nano-flow HPLC on the LCQ ion trap mass spectrometer. Spectra were acquired with the instrument operating in the data-dependent mode throughout the HPLC gradient. Every 12–15 seconds the instrument cycled through acquisition of a full scan mass spectrum and 5 MS/MS spectra recorded sequentially on the 5 most abundant ions present in the initial MS scan. More than 1,500 MS/MS spectra were recorded in this mode of operation during the chromatographic separation. Data acquired in the above experiment was analyzed both by a computer algorithm, the Neutral Loss Tool, and also by SEQUEST. The Neutral Loss Tool searches MS/MS spectra for fragment ions formed by loss of phosphoric acid, 32.6, 49 or 98 Da from the (M+3H) +++ , (M+2H) ++ and (M+H) + ions, respectively. Phosphoserine and phosphothreonine, but not phosphotyrosine, lose phosphoric acid readily during the collision activation dissociation process in the ion trap mass spectrometer. Thus, appearance of fragment ions 32.6, 49 or 98 Da below the triply, doubly or singly charged precursor ions in peptide MS/MS spectra strongly suggests that the peptide contains at least one phosphoserine or phosphothreonine residue. In the above experiment, more than 1,000 different phosphoserine or phosphothreonine containing peptides were detected in the yeast whole cell lysate with the Neutral Loss Tool. To identify phosphopeptides in the above sample, MS/MS spectra were searched with the SEQUEST algorithm against yeast protein database (obtained from the Saccharomyces Genome Database (SGD) genome-www.stanford.edu/Saccharomyces/). Of the 216 sequences confirmed, 60 (28%) were singly phosphorylated, 145 (67%) were doubly phosphorylated, and 11 (5%) were triply phosphorylated. This clearly indicates the potential of the phosphoprofiling approach as a measure of cellular activation states. In fact, we identified 171 different proteins, including abundant species such as the heat shock proteins as well as those involved in carbohydrate metabolism and protein synthesis. Rare proteins, such as the cell cycle regulatory molecules and cytoplasmic proteins, were also observed. Of the 216 confirmed peptide sequences, 66 have sequences which correspond to a codon bias of less than 0.1 and are therefore likely to be expressed in low copy number. Eighty-five additional phosphopeptides were identified by recording MS/MS on the sample eluted from the IMAC column after it had been treated with alkaline phosphatase to remove covalently bound phosphate. In this experiment, peptide methyl esters were eluted from the IMAC column directly to a second column packed with F7m Polyvinyl spheres containing immobilized alkaline phosphatase. De-phosphorylated peptides were then eluted to a standard nano-flow HPLC column and analyzed on an LCQ instrument using the data dependent scan protocol described above. This approach has the advantage that the resulting MS/MS spectra usually contain a larger number of abundant, sequence-dependent, fragment ions than those recorded on the corresponding phosphorylated analogs. This, in turn, improves the likelihood that the SEQUEST algorithm will find a unique match in the protein database. The disadvantage of the protocol is that the resulting MS/MS spectra no longer contain information on the number and location of the phosphorylated residues within the peptide. Finally, we note that the above methodology can be modified easily to allow quantitation and/or differential display of phosphoproteins expressed in two different samples. For this experiment, peptides are converted to methyl esters from one sample with do-methanol and from the other sample with d 3 -methanol. The two samples are combined, fractionated by IMAC, and the resulting mixture of labeled and unlabeled phosphopeptides is then analyzed by nanoflow HPLC/electrospray ionization on a newly constructed Fourier transform mass spectrometer. This instrument operates with a detection limit in the low attomole level. Signals for peptides present in both samples appear as doublets separated by n(3Da)/z (where n=the number of carboxylic acid groups in the peptide and z=the charge on the peptide). The ratio of the two signals in the doublet changes as a function of the expression level of the particular phosphoprotein in each sample. Peptides of interest are then targeted for sequence analysis in a subsequent analysis performed on the ion trap instrument as discussed above. Fractionation of peptides on these columns is based upon their affinity for Fe +3 which is coordinated to chelating agents covalently attached to the packing material. Protein extraction from S. cerevisiae . Yeast strain 2124 MATa ade2-1, ade6-1, leu2-3, 112, ura3-52, his3Δ1, trpl-289, can 1cyh2 bar1::KAN (40 ml) was grown in YPD at 23° C. to a density of 1×10 7 cells/ml. The cell pellet was re-suspended in 1.5 ml of Trizol (Gibco-BRL) and cell lysis performed by homogenization with glass beads in 3 consecutive sessions of 45 sec each in a Fastprep FP120 shaker (Savant). Total yeast protein, free of nucleic acids, was extracted from this yeast lysate using Trizol according to the manufacturer's directions (Gibco-BRL). The protein pellet was re-suspended in 1% SDS (Sodium Dodecyl Sulfate) and dialyzed against 1% SDS using a Slyde-A-Lyzer, 10,000 MW (Molecular Weight) cutoff (Pierce), to remove small molecules and stored at −80° C. To follow the removal of nucleotides, 0.1 μl of a P 32 CTP (Amersham-Pharmacia) was added to a 10 ml equivalent of lysed cells. Aliquots were removed after each step in the purification and the amount of nucleotide quantitated by Scintillation with Scintisafe EconoF (Fischer). Yeast protein, 500 μg (approximately 10 nmol), in 500 μl of 100 mM animonium acetate (pH 8.9), was digested with trypsin (20 μg)(Promega) overnight at 37° C. Solvent was removed by lyophilization and the residue reconstituted in 400 μl of 2N methanolic HCl and allowed to stand at room temperature for 2 h. Solvent was lyophilized and the resulting peptide methyl esters were dissolved in 120 μl of a solution containing equal parts of methanol, water and acetonitrile. An aliquot corresponding to 20% of this material (2 nmol of yeast protein) was subjected to chromatography and mass spectrometry as described below. Chromatography. Construction of immobilized metal affinity chromatography (IMAC) columns has been described previously 9 . Briefly, 360 μm O.D. (Optical Density)×100 μm I.D. (Inner Diameter) fused silica (Polymicro Technologies, Phoenix, Ariz.) was packed with 8 cm POROS 20 MC (PerSeptive Biosystems, Framingham, Mass.). Columns were activated with 200 μl 100 mM FeCl 3 (Aldrich, Milwaukee, Wis.) and loaded with either 0.5 μl of the above standard mixture or sample corresponding to peptides derived from 100 μg (10 nmol) of protein extract from S. cerevisiae . To remove non-specific binding peptides, the column was washed with a solution containing 100 mM NaCl (Aldrich) in acetonitrile (Mallinkrodt, Paris, Ky.), water, and glacial acetic acid (Aldrich) (25:74:1, v/v/v). For sample analysis by mass spectrometry, the affinity column was connected to a fused silica pre-column (6 cm of 360 μm O.D.×100 μm I.D.) packed with 5–20 μm C18 particles (YMC, Wilmington, N.C.). All column connections were made with 1 cm of 0.012″ I.D.×0.060″ O.D. Teflon tubing (Zeus, Orangeburg, S.C.). Phosphopeptides were eluted to the pre-column with 10 μl 50 mM Na 2 HPO 4 (Aldrich) (pH 9.0) and the pre-column was then rinsed with several column volumes of 0.1% acetic acid to remove Na 2 HPO 4 . The pre-column was connected to the analytical HPLC column (360 μm O.D.×100 μm I.D. fused silica) packed with 6–8 cm of 5 μm C18 particles (YMC, Wilmington, N.C.). One end of this column contained an integrated laser pulled ESI (ElectroSpray Ionization) emitter tip (2–4 μm in diameter) 14 . Sample elution from the HPLC column to the mass spectrometer was accomplished with a gradient consisting of 0.1% acetic acid and acetonitrile. For removal of phosphate from the tryptic peptides, the IMAC column was connected to a fritted 360 μm O.D.×200 μm I.D. fused silica capillary packed with F7m (Polyvinyl spheres), containing immobilized alkaline phosphatase (MoBiTech, Marco Island, Fla.). Phosphopeptides were eluted from the IMAC column through the phosphatase column onto a pre-column with 25 μL of 1 mM ethylenediaminetetraacetic acid (EDTA) (pH in the range of from about 5.0 to about 9.0), and the pre-column was then rinsed with several column volumes of 0.1% acetic acid to remove EDTA. Alternatively, phosphopeptides can be eluted using ascorbic acid. The pre-colunm was connected to an analytical HPLC column. Sample elution from the HPLC column to the mass spectrometer was accomplished with a gradient consisting of 0.1% acetic acid and acetonitrile. Mass Spectrometry. All samples were analyzed by nanoflow-HPLC/microelectrospray ionization on a Finnigan LCQ ion trap (San Jose, Calif.). A gradient consisting of 0–40% B in 60 min, 40–100% B in 5 min (A=100 mM acetic acid in water, B=70% acetonitrile, 100 mM acetic acid in water) flowing at approximately 10 nL/min was used to elute peptides from the reverse-phase column to the mass spectrometer through an integrated electrospray emitter tip 14 . Spectra were acquired with the instrument operating in the data-dependent mode throughout the HPLC gradient. Every 12–15 sec, the instrument cycled through acquisition of a full scan mass spectrum and 5 MS/MS spectra (3 Da window; precursor m/z+/−1.5 Da, collision energy set to 40%, dynamic exclusion time of 1 minute) recorded sequentially on the 5 most abundant ions present in the initial MS scan. To perform targeted analysis of the phosphopeptide in the standard mixture, the ion trap mass spectrometer was set to repeat a cycle consisting of a full MS scan followed by an MS/MS scan (collision energy set to 40%) on the (M+2H) ++ of DRVpYIHPF (SEQ ID NO: 1) or its methyl ester (m/z 564.5 and 578.5, respectively). The gradient employed for this experiment was 0–100% B in 30 minutes for the un-derivatized sample, 0–100% B in 17 minutes for derivatized sample (A=100 mM acetic acid in water, B=70% acetonitrile, 100 mM acetic acid in water). Database Analysis. All MS/MS spectra recorded on tryptic phosphopeptides derived from the yeast protein extract were searched against the S. cerevisiae protein database by using the SEQUEST algorithm 10 . Search parameters included a differential modification of +80 Da (presence or absence of phosphate) on serine, threonine and tyrosine and a static modification of +14 Da (methyl groups) on aspartic acid, glutamic acid, and the C-terminus of each peptide. REFERENCES 1. Hubbard, M. J. and Cohen, P. On target with a new mechanism for the regulation of protein phosphorylation. Trends Biochem. Sci. 18, 172–177 (1993). 2. Annan, R., Huddleston, M., Verma, R., Deshaies, R. & Carr, S. A Multidimensional Electrospray MS-Based Approach to Phosphopeptide Mapping. Anal. Chem. 73, 393–404 (2001). 3. Oda, Y., Nagasu, T. & Chait, B. Enrichment analysis of phosphorylated proteins as a tool for probing the phosphoproteome. Nat. Biotechnol. 19, 379–382 (2001). 4. Zhou, H., Watts, J. & Aebersold, R. A systematic approach to the analysis of protein phosphorylation. Nat. Biotechnol. 19, 375–378 (2001). 5. Andersson, L. and Porath, J. Isolation of phosphoproteins by immobilized metal (Fe3+) affinity chromatography. Anal. Biochem. 154, 250–254 (1986b) 6. Michel, H., Hunt, D. F., Shabanowitz, J. and Bennett, J. Tandem mass spectrometry reveals that three photosystem II proteins of spinach chloroplasts contain N-acetyl-O-phosphothreonine at their NH 2 termini. J. Biol. Chem. 263, 1123–1130 (1988). 7. Muszynska, G., Dobrowolska, G., Medin, A., Ekman, P. & Porath, J. O. Model studies on iron(III) ion affinity chromatography. II. Interaction of immobilized iron(III) ions with phosphorylated amino acids, peptides and proteins. J. Chrom. 604, 19–28 (1992). 8. Nuwaysir, L. & Stults, J. Electrospray ionization mass spectrometry of phosphopeptides isolated by on-line immobilized metal-ion affinity chromatography. J. Amer. Soc. Mass Spectrom. 4, 662–669 (1993). 9. Zarling, A. L. et al. Phosphorylated peptides are naturally processed and presented by major histocompatibility complex class I molecules in vivo. J. Exp. Med. 192, 1755–1762 (2000). 10 Eng, J., McCormack, A. L. and Yates, J. R. An approach to correlate tandem mass spectral data of peptides with amino acid sequences in a protein database. J. Amer. Soc. Mass Spectrom, 5, 976–989 (1994). 11. Bennetzen, J. L. & Hall, B. D. Codon selection in yeast. J Biol Chem 257, 3026–3031 (1982). 12. Zhang, X. et al. Identification of phosphorylation sites in proteins separated by polyacrylamide gel electrophoresis. Anal Chem 70, 2050–2059 (1998). 13. Amankwa, L. N., Harder, K., Jirik, F. & Aebersold, R. High-sensitivity determination of tyrosine-phosphorylated peptides by on-line enzyme reactor and electrospray ionization mass spectrometry. Prot. Sci. 4, 113–125 (1995). 14. Martin, S. E., Shabanowitz, J., Hunt, D. F. & Marto, J. A. Subfemtomole ms and ms/ms peptide sequence analysis using nano-hplc micro-esi fourier transform ion cyclotron resonance mass spectrometry. Anal Chem 72, 4266–4274 (2000).

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CROSS-REFERENCE TO RELATED APPLICATIONS This application is a division of U.S. application Ser. No. 07/732,735, filed Jul. 18, 1992, now U.S. Pat. No. 5,194,039, issued Mar. 16, 1993, which was a continuation of U.S. application Ser. No. 07/597,209, filed Oct. 11, 1990, abandoned. BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to vaults, or strong rooms generally and, more particularly, to a novel system for providing fresh air and/or food to a person or persons who may be trapped in such vaults, which system is integral with the vault door, which uses a number of components already existing in conventional locking means used in many vault doors. 2. Background Art Some provision must be made in a vault installation for providing fresh air to a person or persons who may be trapped in a vault as a result of a burglary or even by accident. In most cases, once the door of such a vault has been closed and the locking mechanism activated, it cannot be opened again for some predetermined period of time. Also, there is usually no provision for opening such a door from the inside. Accordingly, provision must be made to provide fresh air, and, in some cases, food or liquid to person(s) trapped in a locked vault. Of course, the means for providing fresh air must be activatable by the person(s) within the vault, since their plight may not be discovered for some time. Heretofore, attempts to address this problem have involved systems employing various types of tubes, sometimes with fresh air blowers, extending through the walls of vaults, which systems are activatable by various means by the person(s)inside the vaults. A substantial limitation of all such systems is that they are installed through the walls of the vaults, sometimes in the area of the door jambs, thus making retrofitting to existing vaults extremely difficult, since the walls and jambs are reinforced against forcible entry. In some cases, also, the walls or jambs must be thickened in the areas of the tubes passing therethrough to maintain the required security and/or fire rating of the vault, thereby increasing the difficulty of retrofitting to existing vaults and, in many cases, decreasing the volume of the vaults which would Otherwise be available for use and decreasing the flexibility of locating internal safety deposit boxes or other internal equipment. With many such known systems, the means to activate the system is cumbersome and difficult. All such known systems are relatively expensive. Accordingly, it is a principal object of the present invention to provide a vault ventilator system which may be installed in the door of the vault. It is an additional object of the invention to provide such a system that employs a number of components already used in vault doors. It is a further object of the invention to provide such a system that can be easily retrofitted to existing vaults. It is another object of the invention to provide such a system that is easily activatable and simply and economically manufactured. An additional object of the invention is to provide such a system the installation of which does not require a decrease in the internal volume in the vault. Other objects of the present invention, as well as particular features and advantages thereof, will be elucidated in, or be apparent from, the following description and the accompanying drawing figures. SUMMARY OF THE INVENTION The present invention achieves the above objects, among others, by providing, in a preferred embodiment, a system for introducing fresh air to a locked vault which is integral to the door of the vault. A fan provides motive force to the air which flows principally through passages in, or created with, existing components in the door. A food/water passage may be furnished by providing the door wheel spindle as a hollow, rather than a solid, tube. BRIEF DESCRIPTION OF THE DRAWING The invention will be better understood if reference is made to the accompanying drawing figures, in which: FIG. 1 is perspective view of a vault door employing the present invention. FIG. 2 is an exploded perspective view of the locking unit of the door of FIG. 1 showing the arrangement of the major elements of the present invention. FIG. 3 is a cross-sectional view of the locking unit of FIG. 2. FIG. 4 is a rear elevation view of the door of FIG. 1. FIG. 5 is a cross-sectional view of the locking unit of FIG. 2 showing alternative means for sealing the food/water passageway of the present invention. DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring now to the Drawing, on which the same elements are given consistent identifying numerals throughout the various figures thereof, there is shown a vault door, generally indicated by the reference numeral 10, which door includes the elements of the present invention. For clarity, the locking/unlocking mechanisms incorporated in vault door 10 are not shown on the drawing figures and it will be understood that such mechanisms may be entirely conventional and that the details of any particularly type used will not affect the practicing of the present invention. With particular reference to FIGS. 1-3, door 10 includes a removable locking unit 12, a front panel 14, a rectangular frame 16, and a rear cover 18. Included in locking unit 12 is a center panel 24 on which are mounted lock combination dials 26 and 28 attached to lock spindles 30 and 32, respectively, which lock spindles are disposed in lock spindle tubes 34 and 36, respectively. Also mounted on center panel 24 is a door wheel 40 attached to door wheel spindle 42 which is disposed in door wheel spindle tube 44. Spindle tubes 34, 36, and 44 are welded between a front plate 48 and an intermediate plate 50. A tempered glass relock protection plate 54 extends over a portion of the rear surface of intermediate plate 50. A hinged cover 58 extends over the portion of center panel 24 containing lock combination dials 26 and 28. So far, the elements described are entirely conventional. The conventional elements which have been revised, or new elements which have been added, for the present invention will now be described. Still referring to FIGS. 1-3, door wheel spindle 42, rather than being solid as is the case with convention door wheel spindles, is hollow, thus forming a passageway 62 between the front of door 10 and the inside of the vault (not shown) on which the door is mounted. Passageway 62 may be used to pass food and/or water to the person(s) trapped inside the vault. In order to compensate for not having a solid door wheel spindle 42, tempered glass relock protection plate 54 has been extended around the area of the door wheel spindle. To provide fresh air to the inside of the vault, a fan 66 is mounted inside center panel 24 to draw air through a fan grill 68 and force it through the existing clearances between lock spindles 30 and 32 and lock spindle tubes 34 and 36, respectively. To ensure that the air in fact passes through such clearances, a gasket 70 is provided between center panel 24 and front plate 48. To provide a further passage for the air once it arrives at the rear surface of intermediate plate 50, tempered glass relock protection plate 54 is raised slightly from the rear surface of the intermediate plate and sealed thereto by a gasket 72 so that the air may pass through a channel 74 defined between the rear surface of intermediate plate 50 and the inside surface of relock protection plate 54. From channel 74, the air passes through an air duct 76 and exits into the vault through a ventilator grill 78 formed in a control panel 80 (also FIG. 4). Mounted behind control panel 80 is a housing 86 which encloses an on/off switch 88 (FIG. 4) and an on/off indicator light 90 (FIG. 4). The rear surface of control panel 80 may include instructions 91. Passageway 62 is opened by moving a slide 92 with an attached knob 94 from the position shown on FIG. 3 to the position shown on FIG. 4 to open the inner end of the passageway and, thus, provide communication between the interior of the vault and the front of door 10. In order to provide more secure closure of passageway 62, the embodiment of the present invention shown on FIG. 5 may be employed. Here, rather than effecting closure of only one end of passageway 62 with a slide, such as slide 92 on FIGS. 3 and 4, there is provided a solid tube 100 which can extend substantially throughout the passageway and which may be removably secured in place therein by advancing a threaded portion 102 into the inner end of the passageway. A knob 104 is provided at the inner end of tube 100 to aid in inserting and withdrawing the tube into and from passageway 62. In use, once a person is locked in the vault, he locates control panel 80, preferably by means of a continuously lit small light (not shown) indicating the position of the control panel, and switches on the fan which action may also turn on emergency lights in the vault. If food, water, or other items are required, these may be obtained through passageway 62 after moving slide 94 to its open position or by removing tube 100 from the passageway. Otherwise, passageway 62 may be employed for the exiting of air, if necessary. It will be understood that the teachings of the present invention could be applied so that stale air is positively removed from the vault by reversing the flow of air produced by fan 66, so that fresh air is drawn into the vault, for example, through passageway 62, and such is within the intent of the present invention. It can be seen that the present invention may be employed without compromising the integrity of the vault walls or the vault door jamb. It will thus be seen that the objects set forth above, among those made apparent from the preceding description, are efficiently attained and, since certain changes may be made in the above construction without departing from the scope of the invention, it is intended that all matter contained in the above description or shown on the accompanying drawing figures shall be interpreted as illustrative only and not in a limiting sense. It is also to be understood that the following claims are intended to cover all of the generic and specific features of the invention herein described and all statements of the scope of the invention which, as a matter of language, might be said to fall therebetween.

4y

FIELD OF THE INVENTION This invention relates to the fabrication of semiconductor devices using electron beam aided processes, such as the use of an electron beam to trace an exposure pattern in the photoresist or other film coated onto an underlying semiconductor or composite substrate. More specifically, the invention relates to a method of exposing the photoresist coating with an electron beam where the accelerating voltage and the amount of charge of the projected electron beam are controlled and correlated to thickness variations in the photoresist, as may result from variations in the underlying topography. Thus, the energy of the electron beam incident upon the photoresist and underlying structures or layers is controlled as the beam is deflected. This permits thorough exposure of the photoresist by the electron beam while minimizing ionizing radiation damage to the underlying semiconductor material, structures, insulating layers, and the like. BACKGROUND OF THE INVENTION As an aid to understanding the problems in prior art methods and apparatus, reference should be made to FIGS. 1A-1F which illustrate a typical series of steps used in electron beam, photo aided, or lithographic processes to manufacture semiconductor devices. Referring to FIG. 1A, a semiconductor substrate 1, such as a slice or wafer of silicon or other composite has grown thereon an insulating oxide layer 2, such as silicon dioxide. A series of steps is undertaken to cut a window or pattern in the silicon dioxide layer and expose a predetermined area of the underlying substrate 1. Referring to FIG. 1B and using like reference numerals for like items, a film of photoresist 3 is coated onto the entire surface of the oxide layer 2. Like photographic film, the photoresist is sensitive to incident radiation, such as an electron beam, visible light, ultraviolet light, or X-rays. Referring to FIG. 1C, a traveling electron beam 4 is moved across the photoresist to expose selected portions. The beam is directed in a manner to expose the photoresist according to a pattern traced or "written" by the beam. This is referred to as maskless or direct processing, and it delineates an exposure pattern by writing directly on the photoresist. Since the electron beam has a shorter wavelength and greater depth of field than many other types of radiation, it is capable of forming very fine exposure patterns, and it eliminates the need to create a cumbersome physical mask, as used with ultraviolet processing, which is time consuming and very costly. In FIG. 1C the exposed portion is indicated by the stippled area 3a. That portion of the photoresist labeled 3b is not exposed to the incident radiation and is not affected thereby. Referring to FIG. 1D, the photoresist is subjected to a process that dissolves and removes the exposed photoresist 3a but does not affect the unexposed photoresist. This leaves a pair of spaced parallel strips 3b of unexposed photoresist separated by a channel 2a of the underlying oxide layer 2. Referring to FIG. 1E, the unexposed photoresist 3b and the oxide layer 2a are treated so as to remove the unprotected oxide, but not the unexposed photoresist 3b, in order to expose a channel 1a of the underlying material 1. Referring to FIG. 1F, the unexposed photoresist 3b has been stripped from the oxide layer in preparation for succeeding process steps, leaving a channel of bare silicon defined by strips of superposed silicon dioxide 2. The desire to increase circuit density on semiconductor material and recent developments in photo aided processes have resulted in the ability to create smaller and smaller circuit elements. Typically, these elements are on the order of a few microns in size or smaller, and they may be composed of layers on the order of only 0.01 microns deep. Thus, it is increasingly important that succeeding processing steps do not disturb the effects of earlier steps, and, for this reason, it is desirable to control the energy of the electron beam or other radiation used to expose the photoresist. In the past the energy of the incident electron beam was not controlled to match the amount of energy required to expose the photoresist or the thickness or depth of the photoresist at a given location. Instead, the electron beam voltage and charge was fixed at a level high enough to expose the thickest portions of the photoresist layer without regard to any problems that might arise where the photoresist was thinner, or where there were other variations in the photoresist coating, or where the underlying structures were "tall," or where the underlying layers were susceptible to damage from the incident electron beam radiation. Some attempts have been made to ameliorate scattering of the electron beam by varying total incident dosages, but this was done at a constant accelerating voltage and without regard to variations in the photoresist thickness. As a result, the electron beam had excess energy in some sectors and the electrons penetrated to the underlying layers or substrate, resulting in unwanted damage. For example, unwanted damage was inflicted upon insulated gate field effect transistors (IGFET) when the accelerating voltage of the electron beam used to expose the photoresist was too high and the electrons penetrated through the photoresist and overlying films to the gate insulator. Experiments have demonstrated that it is desirable to limit the energy density in the underlying layers to less than 10 5 or 10 6 Rads SiO 2 . To achieve exposure of the photoresist in a typical electron beam system, the electrons are accelerated to 20 to 25 kilovolts (KeV), or even as high as 50 KeV, and the photoresist is subjected to dosages of 20 to 30 microcoulombs per square centimeter. At such levels of dosage and at these accelerating voltages, the incident electrons pass through typical thicknesses of photoresist, i.e. two to three microns, and damage the underlying films and semiconductor materials. This produces fixed positive charge and neutral traps, which are undesirable. Prior to the application of a metalizing layer, it was believed that such damage could be annealed by heating the semiconductor wafers in a hydrogen-containing ambient atmosphere in the 550°-700° C. range. However, it has recently been claimed that following repetitive, high energy radiation damage to the gate insulator of a MOS capacitor, even vigorous annealing treatments do not correct the damage done. See A. Reisman et al., "The Effects of Pressure, Temperature and Time on the Annealing of Ionizing Radiation Induced Insulator Damage in N-channel IGFET's," Journal of the Electrochemical Society, Vol. 130 No. 6, June 1983; and A. Reisman et al, "On the Removal of Insulator Process Induced Radiation Damage from Insulated Gate Field Effect Transistors at Elevated Pressure," Journal of the Electrochemical Society, Vol. 128, No. 7, July 1981. Moreover, excessive exposure to high temperatures may alter doping levels or configurations, or unduly stress the lattice structure. Accordingly, there is a great need to minimize the damage caused by the use of high energy electrons and other ionizing radiation during the manufacture and processing of semiconductors. The present invention is based upon the recognition that proper exposure of the photoresist is a function of the energy absorbed by it rather than the accelerating voltage of the electron beam or the amount of charge carried by the beam alone. Stated otherwise, the extent of radiation damage is a function of the total energy absorbed in a given mass of material and not the energy per photon or energy per electron. Thus, the present invention involves matching the energy of the incident electron beam and electron dose to the amount of energy locally required to thoroughly expose the photoresist. This is done by controlling the voltage and the amount of charge of the incident electron beam to correlate to variations in the photoresist thickness. By controlling the voltage, the electron beam will penetrate a predetermined distance with minimal penetration to underlying structures, and by controlling the amount of charge carried by the electron beam, the energy of the electron beam is controlled to thoroughly expose the photoresist. The present invention also has applications in compensating for proximity effects encountered in electron beam processes, and for accommodating topographical variations resulting from the layered construction of the semiconductor. Thus, it is an object of the present invention to provide a method and apparatus for exposing photoresist with an electron beam during the fabrication of semiconductor devices by controlling the voltage and the amount of charge of the electron beam to minimize ionizing radiation damage to the underlying films and semiconductor substrate. It is a further object of the present invention to provide a method and apparatus for exposing photoresist with an electron beam during the fabrication of semiconductor devices by controlling the voltage of the electron beam to substantially penetrate the entire depth of the photoresist thickness with minimal penetration therethrough to the underlying structures. It is a still further object of the present invention to provide a method and apparatus for exposing photoresist with an electron beam during the fabrication of semiconductor devices by controlling the voltage and the amount of charge of the projected electron beam as it is deflected to match the total energy of the electron beam to the amount of energy absorbed by the photoresist during exposure from an incident electron beam. Accordingly, the present invention is a method and apparatus for exposing photoresist with an electron beam during the fabrication of a semiconductor device. The method includes coating a substrate with a photoresist. An electron beam is projected onto the photoresist and deflected to expose the photoresist in a predetermined pattern. The voltage and the amount of charge of the electron beam are controlled as the beam is deflected so that the energy incident upon the photoresist from the electron beam is correlated to variations in the photoresist thickness to expose the photoresist with no significant penetration therethrough to the underlying structures. DESCRIPTION OF THE DRAWINGS FIGS. 1A-1F illustrate a typical series of steps used in electron beam processes to manufacture semiconductor devices. FIG. 2 is a schematic cross-sectional view of an insulated gate field effect transistor. FIG. 3 is a graph of the electron beam particle energy in KeV versus the penetration depth in positive photoresist in microns, according to the Terrill equation. FIG. 4 is a schematic cross-sectional view of a semiconductor in the process of being manufactured illustrating the penetration of incident electrons of different accelerating voltages during the exposure of a photoresist coating. FIG. 5 is a schematic cross-sectional view of a photoresist layer on an underlying substrate being subjected to an incident electron beam, and illustrating the scattering of some of the electrons. DESCRIPTION OF THE INVENTION Referring to FIG. 2, which is not drawn to scale, a cross-sectional schematic view of an n-channel enhancement mode insulated gate field effect transistor is illustrated. It comprises a substrate 10 of p-material, and a source 11 and drain 12 of n+-material separated by an n-channel 13. An electrically insulating layer of silicon dioxide 14 bridges the source and drain and overlies the channel 13. This insulating layer is used as a gate dielectric to separate the gate electrode 15, which is a layer of polycrystaline silicon, from the n-channel 13, and its thickness is usually much less than the nearby silicon dioxide layers 16 used for masking, device isolation, or surface passivation. Metalized contacts 20, 21 and 22 make electrical connections with the source 11, drain 12, and gate electrode 15, respectively. In such an enhancement mode IGFET, there is no conductive channel between the source 11 and drain 12 at zero gate voltage, as measured between the source and gate. As a positive gate bias is applied and increased beyond a threshold value, a localized inversion layer is formed in the n-channel 13 immediately underneath the gate dielectric 14 and it serves as a conducting channel between the source and drain. The conductivity of the induced channel is proportional to the applied gate bias, but it is degraded by fixed positive charge and neutral traps, which are introduced by excessive ionizing radiation, i.e. electron beams of excessive energy. During the course of manufacturing a semiconductor device, such as the IGFET illustrated in FIG. 2, it is necessary to go through numerous cycles of the electron beam processes described in connection with FIGS. 1A-1F. To determine the depth to which an electron will penetrate the photoresist, reference is made to the Terrill equation: ##EQU1## which determines the maximum penetration depth X e for electrons with accelerating potentials in the range 10 3 to 10 5 volts. For the calculations V is in volts, d is the density in grams per cubic centimeter (g/cm 3 ), and X e is in centimeters (cm). For the graph of FIG. 3, d for photoresist was assumed to be 2.00 g/cm 3 . The information in the following table is from the chart is FIG. 3. ______________________________________Electron Beam PenetrationParticle Energy (KeV) (microns) (approximately)______________________________________ 4 0.5 8 212 416 6.520 1024 1528 20______________________________________ Thus, for example, if the photoresist at a particular location is 2 microns deep, the incident electron beam must have a particle energy of about 8 KeV to penetrate therethrough. Similarly, if the electron beam has an energy of 24 KeV, it will penetrate well through the 2 micron deep photoresist to the underlying structures. Referring to FIG. 4, which is not drawn to scale, a schematic cross-sectional view of a semiconductor in the process of undergoing photolithography is illustrated. It is typical of a portion of an IGFET, but it is to be understood that the invention is not limited to IGFET's and may be used for other devices and in connection with other electron beam processing techniques. The device in FIG. 4 comprises a substrate 30 of semiconductor material, such as silicon or a composite material. This substrate is typically on the order of 400 microns thick. A thin layer of silicon dioxide (SiO 2 ) 31 overlies the substrate and it is approximately 0.01 to 0.05 microns thick. It is an active layer and is used as a dielectric between the underlying substrate 30 and the overlying layer of polycrystaline silicon 33. The polycrystaline silicon layer is approximately 0.3 microns thick and acts as a gate electrode. A thicker layer of silicon dioxide 34 overlies the polycrystaline silicon. It is approximately one micron thick and is used for masking, device isolation, surface passivation, or the like. A layer of photoresist 35 overlies the silicon dioxide layer 34 and is approximately three microns thick. Alternately, the photoresist may be of multiple layers. A bottom planarizing layer having portions that are two to three microns thick is used to overlay the topographical features of the underlying substrate being fabricated, such as the surface contours apparent in FIG. 2. A top imaging layer having a relatively uniform thickness of about 0.5 micron overlies the planarizing layer and is exposed in appropriate places by an electron beam to generate a photoresist mask. The local thickness of the photoresist coating may be determined based upon the known topography of the underlying substrate, as is evident from FIG. 2. Although not common, other variations may occur in the photoresist coating, e.g. density, depending upon the particular techniques or coating used, and these variations may be noted as necessary or desirable for use in correlating the accelerating voltage and amount of charge of the incident electron beam. The coated photoresist 30 is subjected to an incident electron beam or other ionizing radiation that is directed to trace a pattern on the photoresist and thereby expose it. The equipment and techniques for this exposure are well known, as are the techniques for controlling the deflection of the electron beam, its accelerating voltage, and the amount of charge of the incident electron beam, as it is deflected. FIG. 4 also illustrates the penetration of a 10 KeV incident electron beam 40 as compared to the penetration of a 25 KeV incident electron beam 41. The 10 KeV electron beam is illustrated as penetrating substantially the entire depth of the photoresist 20, but no more; the 25 the 25 KeV electron beam is illustrated as penetrating the photoresist 35, the passive silicon dioxide layer 34, the polycrystaline silicon layer 33, the active silicon dioxide layer 31, and into the underlying substrate 30. The differences between these two accelerating voltages and the resultant effects are best illustrated by the following hypothetical example. For instance, if three microns of photoresist require that the incident electron beam have 10 KeV of accelerating voltage to penetrate therethrough, a higher accelerating voltage, e.g. 25 KeV, will cause many of the electrons to pass through the photoresist to the underlying films, and this will inflict unwanted damage thereon. The relative degree of penetration of the electrons in terms of the energy absorbed in the three microns of photoresist may be quantified empirically as being roughly proportional to the ratio of the 16th power of the accelerating voltages. Assuming that a 10 KeV electron beam will fully expose photoresist that is three microns deep, a 25 KeV electron beam will penetrate approximately thirteen microns of photoresist, or four times as deep as the 10 KeV electron beam (based on FIG. 3). Therefore only (3/13) or 23 percent of the energy carried by the electrons is absorbed in the photoresist. The remaining 77 percent of the energy associated with the deeper penetrating electrons is wasted or dissipated in the underlying structures as illustrated in FIG. 3B, and this may result in undesirable damage. Since proper exposure of the photoresist is a function of the energy absorbed by it rather than the accelerating voltage alone or the amount of charge carried by the electron beam alone, the amount of charge is also controlled so that the total energy of the electron beam (volts×charge) matches the energy that is absorbed by the photoresist for thorough exposure as the beam is deflected to trace a pattern on the photoresist. The amount of energy so absorbed may be readily determined and depends, in part, upon the density and thickness of the photoresist. Returning to our example, a 10 KeV electron beam with a dosage of 20 microcoulombs per cubic centimeter will impart 2×10 6 ergs per cubic centimeter for the three micron thickness of photoresist. If one uses a 20 microcoulomb per cubic centimeter dosage with a 25 KeV electron beam, the total energy is 5×10 6 ergs per cubic centimeter. However, since only 23 percent of the incident electrons are absorbed in the three micron thickness of photoresist, the total energy absorbed is only (0.23) (5×10 6 )=1.15×10 6 ergs. The remaining 3.85×10 6 ergs of energy is dissipated in the underlying substrate where it may generate the unwanted defects discussed earlier, such as fixed positive charges and neutral traps. The fixed positive charges alter the threshold voltage of an IGFET, and if electrons become trapped in them or neutral traps during usage, the long term stability of the device will be impaired. Accordingly, in the present invention the accelerating voltage of the electron beam is controlled and correlated to thickness variations in the photoresist as the electron beam traces a pattern so that the beam thoroughly penetrates the coated photoresist and dissipates substantially all of its energy therein, without significant penetration therethrough that might damage the underlying structure, particularly the gate and field insulators. And, by controlling the amount of charge of the projected electron beam so that the electron beam energy matches the amount of energy necessary to expose the photoresist, the electron beam thoroughly exposes the coated photoresist with no significant ionizing radiation damage to the underlying substrate. In the past, to insure that the photoresist had been thoroughly exposed, the accelerating voltage was usually increased without regard to excessive penetration of the underlying substrate or energy dissipation therein. From an application's standpoint the invention may be used to compensate for proximity effects, and to compensate for topographical variations resulting from the layered construction of the semiconductor. And, by appropriately controlling the voltage and the amount of charge of the projected electron beam to correlate the energy to variations in the photoresist thickness, the overall efficiency of the process is improved because a higher percentage of the energy of the electron beam is absorbed in the photoresist rather than being wasted in the underlying layers. Referring to FIG. 5, a substrate 50 is coated with a layer of photoresist 51. An electron beam 52 is deflected across the surface of the photoresist to trace the desired patterns, such as two adjacent strips. However, some electrons are reflected out of the target area, as illustrated by reference numeral 53. For those electrons near the center of the target area, such as those comprising beam 52A, any reflected electrons are usually reabsorbed in the target area at adjacent locations, as illustrated by reflected beams 53A, 53B. It is those beams adjacent the perimeter of the target area, such as beams 52B, 52C, 52D for which the full energy potential is not realized due to the escape of certain electrons from the target area. In the past, this problem was corrected by either increasing the dwell time at a constant beam current and beam voltage near the perimeter, or rewriting or overwriting areas already covered by the beam. This is time consuming and costly. Using the teachings of the present invention, the electron beam voltage is tailored to the energy to be absorbed on a given layer thickness to minimize reflection and thereby optimize the electron energy absorption process. This improves efficiency and reduces the undesirable horizontal scattering of the electrons and any associated damage. Similarly, to the extent that there are topographical variations in the underlying structures, as may be seen from FIG. 2, they will result in varying thicknesses of the photoresist as the electron beam is deflected from one point to another. By controlling the voltage and the amount of charge in accordance with the variations in photoresist thickness, the photoresist is exposed with minimal penetration therethrough to the underlying structures. In the drawings and specification there has been set forth an exemplary embodiment of the invention. It should be understood that while specific terms are employed, they are used in a generic and descriptive sense only and not for purposes of limitation.

4y

DESCRIPTION BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates to an environmental exposure indicator and, more particularly, to an indicator that is inactive until it is activated by actinic radiation. 2. Description of the Prior Art Several patents have disclosed the use of color-changing indicators to monitor the time-temperature history of perishables. Among these are U.S. Pat. No. 4,189,399, issued Feb. 19, 1980, to Patel; and U.S. Pat. No. 4,212,153, issued July 15, 1980, go Kydonieus et al. When the perishable to be monitored has a short useful lifetime and/or requires refrigeration, then it is desirable, if not essential, to use an indicator that is inactive until activated. Patel, U.S. Pat. Nos. 4,208,187, issued June 17, 1980, and 4,276,190, issued June 30, 1981, disclosed diacetylenic compositions having an inactive form that is activated by contact with an activating vapor. Activation of a diacetylenic monomer in salt form by conversion to the acid form was disclosed in U.S. Pat. No. 4,373,032, issued Feb. 9, 1983, to Preziosi et al. Photoactivation of a variety of chemical processes has been reported. It is known, for example, that certain onium salts are photoinitiators of cationic polymerization (see, e.g., J. V. Crivello, Polymer Eng. and Sci. 3, 953 (1983); and J. V. Crivello et al., J. Polymer Sci., Symposium No. 56, 383 (1976)). Photogeneration of a hydrohalic acid has been disclosed by S. Maslowski, Appl. Optics 13, 857 (1974) and in U.S. Pat. No. 4,247,611, issued Jan. 27, 1981, to Sander et al. SUMMARY OF THE INVENTION In accordance with the present invention, a photoactivatable time-temperature indicator comprises a mixture of: (a) a thermally unreactive diacetylenic compound and (b) a photosensitive compound that, on exposure to actinic radiation, forms an acid that converts the diacetylene to a thermally reactive product. Preferably, the mixture is in a medium that facilitates transport between the diacetylenic compound and the photogenerated acid. In operation, the present invention provides a process for measuring incremental environmental exposure, which comprises the steps: (a) exposing a photoactivatable indicator to actinic radiation to render it thermally reactive, (b) measuring the reflectivity of the indicator at a specified wavelength, (c) measuring the reflectivity of the indicator at the specified wavelength after environmental exposure, and (d) calculating the incremental environmental exposure by using a pre-established relationship between a change in reflectivity of the indicator and environmental exposure. The process is particularly useful for measuring the incremental environmental exposure of a perishable article, which involves first applying to the article a photoactivatable time-temperature indicator and then following the steps set forth above. The term "time-temperature indicator," as it is used in the present specification and claims, refers to a composition that responds in a measurable and predictable way to the integrated effect of time and temperature. The activation of the time-temperature indicators of this invention is by photogeneration of an "acid," which term is understood to include Lewis acids, Bronsted acids, and the like. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic that illustrates the preparation of a sealed indicator label of the present invention. FIG. 2 depicts the time dependence of reflectivity spectra of an activated system of the present invention held at room temperature. FIG. 3 depicts plots of data that yield the activation energy of the system of FIG. 2. FIG. 4 depicts the time dependence of reflectivity at 630 nm of an activated indicator label of the present invention held at room temperature. FIG. 5 depicts the time dependence of reflectivity at 630 nm of the label of FIG. 4 held at 6° C. DETAILED DESCRIPTION OF THE INVENTION Many articles of commerce--both food and non-food--are perishable. Particularly when the perishable is enclosed in packaging, it may not be readily apparent when the article has exceeded its useful lifetime. It is even more difficult to determine precisely where an article is positioned on an imaginary graph that plots its deterioration as a function of time. Since the rate at which a perishable deteriorates is generally a function of its integrated time-temperature exposure--at least within a restricted range of time-temperature--a time-temperature indicator is a useful tool for those who are concerned with the freshness of perishable products. The indicator must comprise a composition that provides a readily-measurable physical property that changes in a reproducible way with exposure to time-temperature. For convenience, we use color, but other properties are also suitable. For a real-time indicator, the time frame over which the color changes, in the temperature range of interest, must correspond to that over which the perishable product deteriorates. For products that undergo significant changes over relatively short times (a few days, for example) or at relatively low temperatures (zero degrees Celsius, for example) some form of controlled activation is required to assure that color change does not begin until the desired point in time. One possible means of activation is with light or "photoactivation." Potential advantages of photoactivation include (i) activation of color change at a specified point in time, (ii) totally non-intrusive nature of activation process, and (iii) possibility of controlling extent of activation by photodose, thereby providing a range of time-temperature characteristics with a single indicator. Some disadvantages or concerns include (i) possibility of activation by ambient light exposure, (ii) potential difficulties in reproducing activation dose, and (iii) possible acceleration of color change due to activating radiation. Certain diacetylenic salts, designated for convenience as MOOC-DA, are inactive either in crystalline form or in solution, while the corresponding free acid HOOC-DA is active in crystalline form. In aqueous media, salts of acids generally precipitate out as crystalline materials as the pH of the system is lowered below the pK a of the acid: H.sup.+ +.sup.- OOC-DA⃡HOOC-DA (xtal) (a) Preferred diacetylenic compounds for the present invention are of the form (A) a salt of[HOOC--(CH 2 ) n --C.tbd.C--C.tbd.C--(CH 2 ) 2 --C.tbd.C] 2 (B) a salt of [HOOC--(CH 2 ) n --C.tbd.C--C.tbd.C--CH 2 ] 2 and mixtures thereof, where n is in the range 1-7. A number of chemical compounds are known to generate acids upon excitation with actinic radiation. In aqueous media the acid so produced can lower the system pH, so long as the pK a of the acid is less than the pH of the medium (at least to a first approximation). Thus, if an aqueous medium containing a diacetylenic salt (at pH above the pK a for the diacetylenic acid) is combined with a material that photogenerates strong acid, then excitation by actinic radiation can lower the pH of the medium. In this way, an active form of diacetylene can be precipitated. A number of considerations should be taken into account in optimizing such a system: Photoactivation of the acid should occur at wavelengths long enough that photopolymerization of the diacetylene does not occur. Typically, this means that wavelengths longer than 300 nm should be used. A UV screen cover sheet, which passes radiation only at wavelengths longer than 350 nm, is a convenient means to prevent photopolymerization by ambient radiation, while still passing the actinic radiation needed for photoactivation. Thus, activating wavelengths longer than 350 nm are preferred and polyester is a preferred cover sheet material. But long activating wavelengths can also cause problems. If time-temperature exposure is monitored by changes in reflection density, then it is important that the light whose reflection is being measured not be capable of causing additional activation. Since it is convenient to use visible-light reflection, preferably there should be no activation at wavelengths longer than 400 nm. Thus, a material absorbing at wavelengths shorter than 400 nm and activatable at wavelengths longer than 300 nm, preferably longer than 350 nm, would be desired for the photoacid. In some cases, an opaque covering may be necessary to prevent unintended activation by ambient radiation. A photoreaction that could easily be driven to completion might be desirable, since the resultant activation could be relatively independent of precise radiation dose. On the other hand, if different levels of photoactivation are generated by different doses of actinic radiation, then a single material can serve as an indicator over a wide range of time and temperature. The photoacid should be thermally stable in the application environment; i.e., it should not be thermally activatable. Transport phenomena must be taken into account. For example, in a highly viscous medium, the crystallization process might be too slow for the desired time-temperature indication. Also, transport of H + ions must be sufficient to allow reaction (a) to occur on the appropriate timescale. Although the aqueous medium must permit sufficient mass transport to provide the necessary change in pH, preferably it can be coated onto paper, plastic, or other suitable absorbent substrate. Filter paper is a preferred substrate. The need for a UV screen to shield the indicator from polymerization and the need to permit mass transport can be addressed simultaneously by sealing the indicator between a cover sheet and a base sheet to form a label. A sealed label would provide several advantages: (1) The label can be made rather inexpensively. (2) The sealed system can provide the advantage of easy handling. (3) Wide varieties of clear plastic materials are available that can easily be sealed off thermally, can provide an oxygen and moisture barrier, and can block light having wavelength less than 300 nm to prevent photopolymerization of the diacetylene. (4) Once laminated, the label can be stored in the dark for an extended period and the system can be put in operation when required by exposing the label to actinic radiation. Preferred diacetylenic compounds for the present invention are the salts, preferably the sodium salts, of the acids ##STR1## and mixtures thereof. The salts are inactive as t-T indicators, while the corresponding free acids are active. o-Nitrobenzaldehyde efficiently undergoes photochemical conversion to the corresponding nitrosobenzoic acid: ##STR2## Compared with normal aliphatic carboxylic acids (pK a ˜4.8), benzoic acids are strong acids (pK a ˜4.2) and benzoic acids that are orthosubstituted with electron withdrawing groups are stronger yet (o-nitrobenzoic acid, pK a ˜2.2; o-chlorobenzoic acid, pK a ˜2.9). Thus, o-nitrosobenzoic acid (IV) is a strong acid relative to aliphatic carboxylic acids. An alternative to o-nitrobenzaldehyde for the photosensitive compound is 2,2,2-tribromoethanol (CBr 3 CH 2 OH). This compound generates HBr when it is exposed to UV light. A drawback of the compound is that activation requires a light of wavelength about 260 nm or less, which can cause undesirable polymerization of the diacetylene. Compared with a system using o-nitrobenzaldehyde, a 2,2,2-tribromoethanol system also responds more slowly at a given temperature. Preferably, the medium that surrounds the diacetylenic and photosensitive compounds comprises a polymer, such as polyvinyl alcohol (PVA) or gelatin. A preferred medium is PVA that is 50-100 percent hydrolyzed or, more preferably 70-90 percent hydrolyzed. The weight-averaged molecular weight of the PVA may be in the range from about 500 to about 500,000, with about 110,000 preferred. The following examples are presented in order to provide a more complete understanding of the invention. The specific techniques, conditions, materials, and reported data set forth to illustrate the principles and practices of the invention are exemplary and should not be construed as limiting the scope of the invention. EXAMPLE 1 An aqueous medium was prepared by partial hydrolysis of a PVA obtained from Aldrich, which had a molecular weight of 115,000. An ultraviolet-transparent medium was prepared by mixing 2 grams of polymer in 100 mL of water. Into 5 mL of the medium was placed 0.015 g of a mixture of compounds I and II (denoted I-II) and 0.012 g of finely ground o-nitrobenzaldehyde (III). Four identical 2 mm cuvettes were filled with the resulting viscous solution. Cuvettes C and D were irradiated for 10 seconds with a commercial UV lamp (100 W Mercury Lamp, Oriel Corp.). Cuvettes B and D were placed in an oven at 60° C., while cuvettes A and C were maintained at room temperature. After 24 hours the cuvettes were examined visually. The contents of cuvettes A, B, and C were colorless, while those of cuvette D had turned dark purple as indicated in the table: ______________________________________Sample Irradiation Time Temperature Color______________________________________A No 24 hr 20° C. noneB No 24 hr 60° C. noneC Yes 24 hr 20° C. noneD Yes 24 hr 60° C. dark purple______________________________________ Unactivated samples remain colorless for several days at 60° C. EXAMPLE 2 Three strips of white filter paper (Whatman No. 41, 5 cm×1.5 cm) were saturated with the solution described in Example 1. Strips A and B were irradiated with light from the same lamp for 20 sec, after which both strips became slightly blue. Strip A was heated with a hot air gun for few seconds. This strip turned red while strip B remained slightly blue. Strip C (not activated) exhibited no color change when heated in a similar manner. EXAMPLE 3 Strips prepared as above were laminated between pieces of polyethylene film. Strips A and B were irradiated for 90 sec as described above. Strips B and C were placed in an oven at 60° C. for 120 minutes. Strip B turned red while strip C remained colorless and strip A remained slightly blue. These observations are summarized in the following table. ______________________________________Sample Irradiation Time Temperature Color______________________________________A Yes 120 min. 20° C. light blueB Yes 120 min. 60° C. redC No 120 min. 60° C. colorless______________________________________ EXAMPLE 4 Indicator labels were prepared as follows: A polymeric gel was prepared by dissolving 4 g of 99-100% hydrolyzed, 115,000 MW PVA powder (purchased from Aldrich, Cat. #18251-6) in 100 mL water at 80° C. The coating mixture ("mix") was prepared by grinding together equal amounts (8 mg each) of compounds III and I-II in 1 mL of the gel. A disc of filter paper (1 cm diameter) as then soaked thoroughly in the "mix" and the resulting coated piece was placed between two sheets of transparent, heat-sealable polyester film (obtained from Kapak Corp.). The excess fluid was removed by rubbing the top surface of the film with a paper towel. The edge of the film surrounding the piece of filter paper was then thermally sealed. The excess film areas were trimmed off and the labels were washed in water and stored in the dark at room temperature. The steps involved in the lamination procedure are shown in FIG. 1. Photoactivation of the labels was accomplished by irradiating each with an Oriel 100 W mercury arc lamp for 60 sec under identical conditions. Polyester film filtered out light having a wavelength shorter than 300 nm. Once activated, the extent of t-T color response due to thermal polymerization of the active free acid was monitored spectrophotometrically as follows. A Perkin-Elmer UV-visible spectrophotometer Model 553, with an integrating sphere attachment, was used to record spectra in the visible region. The integrating sphere attachment was calibrated to 100% reading for a wavelength of 400-750 nm in reflectance measurements by mounting unactivated labels in the reference and the sample holders. The holders were designed to accept samples of 1.2 cm×2.2 cm minimum. Therefore, black masks with 1 cm circular opening were used to accommodate the samples. This modification was necessary to obtain a reasonable signal-to-noise ratio and to obtain good reproducibility. During the measurements of the progressive color change, the activated label replaced the unactivated one in the sample holder. The color change due to partial polymerization was measured either directly as a decrease in reflectivity (%R) or as -log R, which is roughly equivalent to absorbance. FIG. 2 shows representative spectra as a function of time for the samples held at 21° C. With time, progressive bands appeared at 580 nm and 630 nm. Absorbances at 630 nm were plotted as a function of time to obtain a measure of the relative reaction rate. The rate data were tested for samples held at two different ranges of temperatures. In one set of experiments, the samples were held at 66° C., 52° C. and 32° C.; in another set, the temperatures were 25° C., 16° C. and 6° C. (refrigeration temperature). The initial slopes of the rate plots gave relative rate constant, k, in units of absorbance hr -1 . In FIG. 3 the values of k obtained from the two sets were plotted as ln k vs. T -1 to obtain the activation energy. Both sets of measurements gave an activation energy of approximately 20 kcals/mole. These results suggest that mass-transport phenomena are not the limiting factor in this system, down to temperatures as low as 6° C. The decrease in reflectance was also monitored using an optical scanning wand that reads black and white reference bar codes and quantitatively measures the reflectance of a colored element relative to the reference bars. The scanner system employs 632 nm light output. Measurements with the optical wand showed sample reflectivities decreased from approximately 70% (after 80 sec. of photoactivation) to a minimum of approximately 15% with time-temperature evolution. This decrease occurred in 10 days at room temperature. A typical plot of reflectivity vs. time is shown in FIG. 4. All reflectivity values are averages of at least ten scans. Typical results showing color change of an activated indicator with time at 6° C. appear in FIG. 5. As expected, color change at 6° C. was found to be rather slow. However, progressive color chnage was observed, and final color developed over a period of a few weeks. The measurements with the wand correlated well with those obtained from the Perkin-Elmer instrument. Photoactivation always produced a faint blue color and the final color developed as deep blue-violet. Once activated, the progressive color development appeared almost the same for samples left either in the dark or under room light (monitored by measuring %R at 630 nm) provided temperature remained constant. Results with different periods of photoactivation in the range from 30-120 sec show that the thermal activation rate for these indicators depends upon the amount of photoacid production.

4y

This application is a provisional of 60/006383 filed Nov. 8, 1995. BACKGROUND OF THE INVENTION The present invention generally relates to deformable, pressure-compensating padding devices such as seats, cushions, boot liners, mattresses etc., which are used in situations where the human body is in prolonged, abutting contact with a mechanical device. More specifically this invention relates to deformable, pressure-compensating compositions contained in such padding devices, wherein said compositions include a viscous fluid formed by a mixture of an oil and a block polymer. A wide variety of viscous, deformable, pressure-compensating compositions (often referred to as "thixotropic compositions") have been developed for use in seats, cushions, mattresses, fitting pads, athletic equipment (e.g., ski boot liners), prosthetic devices and similar mechanical apparatus which are placed in prolonged contact with the human body. Such compositions provide both firm support and comfort because they have the capacity to deform in response to continuously applied pressure, but they also have the ability to maintain their shape and position in the absence of continuously applied pressure. Pads designed for use with such compositions allow the pressure-compensating compositions contained in them to deform in response to continuously applied pressure and thereby adapt to the contour of a particular part of the human body. Representative pressure-compensating compositions and/or padding devices are described in several patent references. The Prior Art U.S. Pat. No. 4,588,229 to Jay teaches a seat cushion which comprises a flexible envelope filled with a pressure-compensating, fluid material. The Jay patent refers, inter alia, to U.S. Pat. Nos. 4,038,762; 4,144,658; 4,229,546; 4,243,754; and 4,255,202 to Swan which disclose a variety of viscous, flowable, pressure-compensating compositions which consist essentially of a major portion of petroleum-based oil (such as "Carnea" 21 or "Tufflo" 6204) and a minor amount of a petroleum-based wax (such as HM-1319) and a minor amount (by weight) of glass microballoons or lightweight, resinous microballoons or mixtures thereof. U.S. Pat. No. 4,728,551 to Jay teaches a flowable pressure-compensating material, confined in a pad or envelope, which contains a flowable, continuous phase of oil which in turn contains a discontinuous phase comprised of discrete hollow microballoons and colloidal silica particles. The resulting pressure-compensating material flows in response to continuously applied pressure, but is essentially non-flowable in the absence of such pressure. The overall composition is relatively insensitive to temperature variations at those temperatures where these devices are normally employed (e.g., ambient and/or body temperature conditions). It is of paramount importance that the deformable pressure-compensating compositions maintain their ability to deform in response to continuously applied pressure under all conditions of use. The prior art oil/wax compositions noted above perform reasonably well in many room and/or body temperature-defined situations. However, when these prior art compositions are subjected to temperatures higher than body temperatures or when subjected to body temperatures for long periods of time (i.e. six months or longer), the microballoons sometimes separate from the continuous phase materials or some of the fluid from the continuous phase separates from the continuous phase which results in the formation of non-deformable lumps in the composition. Separation is common in some prior art compositions after 6 months use, even without being subjected to temperature extremes. When such separation occurs, irrespective of the cause, the composition loses its ability to deform in response to continuously applied pressure and the non-deformable lumps which are formed by the separation can cause pressure build-up on the skin in the area of the lump and consequent skin damage. The separation may take place quickly particularly when the composition is exposed to elevated temperatures and, in many instances, the separation is irreversible. For example, unacceptable instances of phase separation of various oil/wax/microballoon compositions has been observed in cushions left in closed automobiles in strong sunlight. Under such conditions, temperatures above 120° F. and even temperatures of 170° F. are not uncommon and under such conditions serious, and often permanent, phase separation problems have taken place. It is highly desirable that the deformable, pressure-compensating compositions maintain a stable, unchanging viscosity throughout the temperature range in which such compositions are used. Those skilled in the art also will appreciate that the viscosity of many oil/wax formulations can change drastically in those temperature ranges encountered during normal use. For example, in moving from about room temperatures (e.g., 75° F.) to skin temperature (95° F.), the apparent viscosity of some oil/wax systems may drop by as much as 50%. Consequently, as compositions of this type are warmed to near skin temperature conditions (e.g., this occurs after about two hours of constant sitting upon a wheelchair cushion), such compositions often develop a "watery" texture, i.e. the composition looses its ability to maintain its shape and position in the absence of continuously applied pressure. This is undesirable because a watery or readily deformable composition will no longer afford the same physical stability and support for the user of the pad. Stability and support are prime requirements in the wheelchair seating of disabled persons since such persons tend to easily lose their vertical stability when sitting on unstable seating surfaces. The hydrocarbon oil/wax compositions of the prior art, largely owing to the presence of their hydrocarbon type oil component--possess poor flame retardancy qualities. Obviously, pressure-compensating compositions having better flame retardant qualities are to be preferred. Government regulations are becoming increasingly stringent with regard to flammability issues concerning home, public, and private care facility furnishings. With this high level of awareness given to flame safety, materials of construction that are inherently flame retardant will be favored over those materials that do not meet the applicable flame regulations. The design of such deformable, pressure-compensating compositions must take several--often competing--factors into simultaneous consideration. These factors include: (1) weight: the composition should be light in weight because the less a product weighs, the easier it will be to handle and move; (2) viscosity stability with respect to temperature change: the deform and feel characteristics and position holding capabilities of such compositions should be temperature invariant as much as possible at those temperatures at which these devices are commonly used e.g., such compositions should not become "runny" at elevated ambient temperatures or "stiffen up" at relatively cold ambient temperatures; (3) viscosity stability with respect to extended use: the viscosity of the composition should not change over time as the composition is used; (4) phase separation resistance: compositions having multiple components should not separate into two or more phases with the passage of time; (5) low cost: lower costs are always of concern to both the manufacturer and the consumer; (6) skin irritation: The composition should not pose a significant skin sensitization or irritation potential; (7) micro-organism growth: The composition should have a low micro-organism food value potential in order to inhibit the growth of micro-organisms; (8) non-poisonous: The composition should have a high LD50 threshold (low risk of poisoning upon ingestion); (9) chemical compatibility with the envelope: The composition must not react with or permeate through the envelope in a manner which will result in leakage of the composition from the envelope, or cause a change in the physical properties of the envelope material or instability or phase separation of the composition; (10) flame resistance: such compositions are preferably non-hazardous. For example, they should be able to pass a recognized flame retardancy test e.g., tests such as those like, or substantially similar to, the so-called "Cal 133 test" (California Technical Bulletin 133 Flame Resistance Test) which is used to test the flame retardancy qualities of whole articles items, such as upholstered furniture and seating devices, or the "Cal 117 Test" which is used to test the resilient filling materials used within upholstered furniture; (11) ignition resistance: such compositions are preferably resistant to ignition as determined by a recognized test such as the so-called "Cal 117 test" (California Technical Bulletin 133 Flame Ignition Resistance Test). U.S. Pat. 5,362,543 to Nickerson discloses a pressure compensating composition comprising a major portion of silicone fluid, a minor portion of amide thickener which is essentially insoluble in the silicone fluid, and microballoons. However, although it represents an advance over prior compositions, there is still a need for improvement, particularly regarding cost, flame retardancy, weight, and resistance to separation. SUMMARY OF THE INVENTION The present invention is directed to padding device comprising a flexible envelope and a deformable composition within said envelope wherein the composition comprises a thixotropic fluid formed from a mixture of an oil and a block polymer; wherein the block polymer has least one block which has a relatively low affinity for said oil and having at least one block which has a relatively high affinity for said oil. In the preferred embodiment the thixotropic fluid a micellular emulsion. The compositions are substantially incompressible and thixotropic, i.e., they deform when subject to continuous pressure, but tend to retain their shape in the absence of such pressure. The preferred micellular emulsion comprises a major portion of an oil and a minor portion of a diblock polymer. Microballoons are preferably added and uniformly dispersed throughout the micellular emulsion in order to reduce the density and adjust the viscosity of the composition, as well as reduce cost in some instances. A flame retardant, particularly an intumescent flame retardant, is also preferably added to the composition in applications where flame resistance is desired. Other additives may also be used, such as supplemental thickeners, biocides and antioxidants, to adjust viscosity, prevent microorganism growth and prevent degradation. A fundamental characteristic of the thixotropic fluids of the present invention is that they include a combination of compatible-incompatible components, preferably in the form of micellular emulsions, formed by the interaction of an oil and a block polymer. The present invention contemplates the use of diblock polymers, triblock polymers or higher polymers. A "diblock polymer" is a polymer having two different types of homopolymer blocks joined together to form a single polymer comprising the two different blocks. A "triblock polymer" is a polymer having two different types of homopolymer blocks with the end blocks being of the same homopolymer, but differing from the central homopolymer block. The preferred diblock polymers are thermoplastics wherein one block of the polymer is a rigid plastic, such as polystyrene and the other block is a soft rubber-like elastomer, such as polybutadiene. Depending upon which diblock polymer is selected the elastomeric block may either be fully saturated, such as poly(ethylene-propylene), or unsaturated (containing double bonds at certain carbon to carbon sites along the chain), such as polybutadiene or polyisoprene. Such diblock polymers are sold commercially by Shell Chemical Co. under the name Kraton G1701 and Kraton G1702. They are also sold by Dexco Polymers under the name Vector 6030. Other potential sources include EniChem America Inc Europrene and Sol-T line of products and Nagase America Corporation Septon line of products. A variety of oils may be used. The preferred oil is either a fully saturated polyalphaolefin (PAO), or a canola vegetable oil. The most preferred PAO is commercially available from Amoco Corporation as Durasyn 168, while the most preferred canola oil is a partially hydrogenated and fractionated canola vegetable commercially available from Alnor Oil Co. In addition to the PAO oils, or vegetable oils, other oils such as polybutene oils, dialkyl carbonate oils, and paraffinic mineral oils have also been found to form micellular emulsion fluids with suitable diblock polymers that are suitable for pressure-compensating pads and the like. Also, it has been found that in addition to canola oil, other vegetable oils such as olive, corn, safflower, rapeseed, sunflower, castor, soy, coconut, palm oils and mixtures thereof may be mixed with diblock polymers having one block polystyrene and the other block polybutadiene or polyisoprene to form fluid micellular emulsions that are suitable for pressure-compensating pads. One advantage of the vegetable oil formulations is the relatively low cost of the vegetable oil component. Another advantage is that adequate ignition resistance can be achieved with low levels of flame retardant or with no flame retardant. The rigid polystyrene blocks of the diblock polymers have a poor affinity for the oil and the polystyrene blocks cluster together into groups, while the elastomer blocks have a relatively strong affinity for the compatible oil and are drawn outward from the clustered polystyrene blocks into the surrounding oil. In order to form the thixotropic fluids of the present invention that include the combination of compatible-incompatible components and the preferred micelles, it is believed that, in general, the solubility parameter of the oil should be relatively close to the solubility parameter of one block of the block polymer, while the solubility parameter of the oil should be relatively different from the solubility parameter of the other block of the diblock polymer. In other words, one block of a diblock polymer will have an affinity for and tend to dissolve into the oil, while the other block will be insoluble in and tend to be repelled by the oil. It is theorized that this causes the diblock polymers to organize themselves into micelles with their insoluble blocks clumped together in the center and their soluble blocks extending outward into the surrounding oil (similar to the way that the hydrophobic and hydrophilic ends of soap molecules behave in water). It is theorized that the interaction/intertangling of the many elastomer blocks extending out from the micelles causes the thickening effect which turns the oil into a thixotropic, grease-like composition. Moreover, the strong affinity of the oil for the elastomer blocks makes the composition highly resistant to separation, e.g., bleeding out of the oil from the composition. It is theorized that triblock polymers exhibit similar thickening mechanisms, but are less preferred because the extra block of the polymer can become associated with adjacent micelles, causing long range ordering and structure within the composition resulting in relatively high viscosities. It is preferred to add microballoons to the thixotropic composition in order to reduce its density and adjust viscosity, as well as reducing the cost in some cases. The microballoons may be formed from phenolic or other plastic materials, glass or ceramic materials. Plastic microballoons are generally preferred because they are considerably lighter than glass or ceramic microballoons. Plastic microballoons offer additional benefits in that they can undergo instantaneous compression and recovery (rebound) for impact padding uses. Moreover, it has been unexpectedly found that the preferred flame retardant additives, described below, are dramatically more effective when plastic microballoons are used as opposed to glass, ceramic, or phenolic microballoons. This great increase in flame resistance when plastic microballoons are used allows many materials to be rendered sufficiently flame resistant that simply could not be accomplished practically without the plastic microballoons or with glass, ceramic, or phenolic microballoons. This is all the more surprising since glass and ceramic microballoons are a non-flammable, non-fuel source material and so would normally be expected to impart more flame resistance. The specifically preferred variety of plastic microballoons have a PAN/PMMA (polyacrylonitrile and polymethylmethacrylate) shell surrounding an isobutane gas blowing agent, sold by Nobel Industries under the commercial name Expancel 091 DE microballoons. There are a number of known flame retardants which can be added to the deformable compositions of the present invention. The preferred type is an intumescent flame retardant (IFR), which forms a fluffy, carbonaceous foam char as an ashy by-product when the composition is burned. The system consists of three chemical parts: a catalyst, a carbon source, and a blowing agent. In the preferred embodiment, the catalyst is a phosphoric acid that has been neutralized to an ammonium salt form and polymerized into a long chain to reduce moisture effects and undesirable chemical reactions with other composition formulation components; (ammonium polyphosphate or APP); the carbon source is pentaerythritol (a polyol or polyhydric alcohol); and the blowing agent, which does not take part in the reaction, but degrades with heat, giving off ammonia, nitrogen, carbon dioxide, and/or water, is a melamine formaldehyde coating encapsulating the APP particles (which helps prevent potential skin irritation problems). The blowing agent can also be added separately. Other blowing agents include melamine, melamine phosphate, melamine cyanurate, azodicarbonamide, dicyandiamide, diguanamide, and others. Although IFRs are preferred, other flame retardants may also be used. They generally work in one of four ways: (1) they interfere with flame chemistry in the solid phase, (2) they interfere with flame chemistry in the gas phase, (3) they absorb heat, or (4) they displace oxygen. Examples of these other types of flame retardants include halogenated aromatic or aliphatic compounds; hydrated metal oxides, other metal oxides (e.g., zinc, molybdenum, iron, antimony, boron, and combinations), char forming and glass forming compounds, e.g. borates and silicones, and gas formers (melamines, formaldehydes, ammonium compounds, higher amides, and carbonates). "Synergists" may also be added to improve the performance of any one or combination of these retardants. Synergists include antimony oxide, zinc, boron, bismuth, tin, iron, and molybdenum metals and compounds. Some of these materials are used singly in certain flame retardant formulations. Most often they are used in conjunction with other flame retardants, especially the halogenated varieties. It will be understood that each type of flame retardant will require a minimum loading to pass a particular flame resistance standard. The deformable pressure-compensating compositions of the present invention are especially useful as filling materials for deformable, pressure-compensating padding devices comprising a flexible protective envelope having a cavity which contains the composition and which envelope has structure which allows the composition to deform in the cavity in response to a continuously applied load upon said envelope, but to maintain position in the absence of pressure. The deformable compositions of the present invention are particularly characterized by their: (1) ability to deform by flowing in response to continuously applied pressure, (2) tendency to maintain their shape and position in the absence of a continuously applied pressure, (3) lack of resiliency, under pressure loadings normally associated with seating or mattress applications (4) small changes in viscosity when subjected to changes in temperature, (5) resistance to phase separation of their thickener and/or microballoon components, (6) exceptional flame retardancy qualities, (7) chemical compatibility with polyurethane films, (8) excellent skin contact characteristics (i.e., very low probability of skin irritation), (9) essentially non-poisonous, (10) low microorganism growth potential, and (11) viscosity stability over time. It should also be noted that the novel compositions of the present invention may also be used for a very broad range of other applications, such as prosthetic and other medical devices, wheel chair or other seating, mattresses, helmet padding, bicycle seats, knee pads, athletic equipment pads, handles, seating--virtually any place where foam is now used. DESCRIPTION OF PREFERRED EMBODIMENTS Ranges of Relative Proportions of Ingredients The two basic components of the thixotropic fluids of the present invention are an oil and a compatible/incompatible block polymer. The combination of the oil and the block polymer forms a viscous, grease-like thixotropic fluid. This viscous, thixotropic fluid serves to suspend the non-liquid components of the composition and prevent them from settling and separating. The viscous, thixotropic fluid largely determines the final viscosity profile of the composition, although the addition of the non-liquid components does modify the viscosity profile of the composition. Optional additives include supplemental thickeners, microballoons, flame retardants, biocides and antioxidants. However, if the viscous, thixotropic fluid and the non-liquid components are blended together within a narrow, but controllable range of weight ratios a composition having an acceptable viscosity profile is produced. Table 1 below gives some approximate useable and preferred ranges by weight for the components of the compositions of the present invention. TABLE 1______________________________________GENERAL FORMULATIONSIngredient Usable Range Preferred Range______________________________________Oil 20 to 95 55 to 80Diblock Polymer 2 to 22 3 to 15Supplemental Thickener 0 to 20 3 to 10Microballoons:Plastic 0 to 15 2 to 15Glass 0 to 50 5 to 40Flame Retardant 0 to 40 6.5 to 32Biocide 0 to 2.0 0.2 to 1.0Antioxidant 0 to 3.0 0 to 0.3______________________________________ These grease-like compositions generally have a useful viscosity range of about 100,000-1,000,000 centipoise (cps). However, for pressure relieving applications the preferred useful viscosity range is generally between about 100,000-280,000 cps, with the most preferred viscosity of the final formulation being between about 180,000-200,000 cps when me The Oil The preferred oil used to prepare the grease-like, thixotropic fluids of the present invention is either a polyalphaolefin (PAO) oil, or a canola oil. The most preferred PAO oil is sold commercially by Amoco Corp. as Durasyn 168, which is a hydrogenated homopolymer of 1-decene with a molecular weight of about 1120. The most preferred canola oil is a partially hydrogenated, fractionated canola oil available from Alnor Oil. Other oils found to be suitable with diblock polymer to form the thixotropic fluids of the present invention include other vegetable oils, polybutene oils, dialkyl carbonate oils, and paraffinic mineral oils. PAO Oils PAO oils are synthetic, saturated aliphatic oils, which are polymerized from a variety of feedstocks. The "Durasyn" brand of PAO oils are produced from a 1-decene (10 carbon chain) feedstock from Amoco Corporation. The Durasyn PAO oils are Unavailable in a wide variety of molecular weights depending upon the number of 1-Decene units that are incorporated into the final molecule. The solubility parameter is generally independent of molecular weight in PAO oils, although PAO oils having different molecular weights do display differing physical and chemical properties. For the purposes of creating a deformable composition within the present invention, the properties of interest included viscosity, viscosity index, density, closed cup flash point, and solubility parameter match with the elastomer block of the selected diblock thickener. Matching the solubility parameter between the PAO oil and the diblock thickener is a first step in picking the best combination of materials to prepare the compositions of the present invention, but other factors, sometimes unknown, also appear to influence the properties of the composition. As a general rule, lower molecular weight materials do not need to have solubility indexes as close as is required for higher molecular weight materials. For example, it was found that above a certain molecular weight of PAO oil, the thickener was no longer effective. The lower molecular weight PAO oils also exhibit a lower flash point temperature as measured by the ASTM D 92 closed cup method. For the purposes of maximizing the flammability resistance of this formulation, it is desirable to reduce the ease with which flammable compounds are volatilized from the solid or liquid state into a vapor state. For this reason it is desirable to have as high a molecular weight as possible to maximize difficulty in volatilizing the oil. This is reflected by the higher flash points for higher molecular weight PAO oils. Viscosity index is a measure of how quickly a material decreases viscosity with heat and increases viscosity with cold. The higher numbers indicates more stable materials and is more desirable. Within each family of oils, the viscosity index is generally independent of molecular weight. It was found that the Durasyn 168 exhibited the best combination of properties for use in the compositions of the present invention. These values are listed in Table 2 for the various Amoco "Durasyn" PAO oils. TABLE 2______________________________________ Viscosity, cSt,Product ID Molecular Wt. 40° C. Flash Point, °C.______________________________________Durasyn 162 287 5.54 >155Durasyn 164 437 16.8 215Durasyn 166 529 31.0 235Durasyn 168 596 46.9 253Durasyn 170 632 62.9 264Durasyn 174 1400 395.0 272Durasyn 180 2000 1250.0 288______________________________________ Vegetable Oils Vegetable oils have also been found to form suitable thixotropic fluids and deformable compositions for use in pressure-compensating pads according to the present invention. Vegetable oils have the advantage of being lower cost than the PAO oils. Compositions formulated from vegetable oil based fluids are ignition resistant and will pass testing similar to the Cal 117 ignition test (the composition will not burn after exposure to a Bunsen burner flame for 12 seconds). The diblock polymer preferred for use with vegetable oils has one polystyrene block and one polybutadiene block. The polybutadiene block has unsaturated carbon bonds that apparently result in a solubility parameter which is similar to that of various vegetable oils, which also have unsaturated carbon bonds. To produce micellular emulsions using vegetable oil generally requires heat and substantial agitation. Because vegetable oils are typically unsaturated, it may be desirable to add antioxidants. The lower cost and better resistance to ignition of the vegetable oil based compositions make them potentially desirable. Examples of suitable vegetable oils include olive, corn, safflower, rapeseed, sunflower, castor, soy, coconut, palm, and others of the triglyceride family. The vegetable oils may be hydrogenated and/or hydrogenated and fractionated in order to provide a lower degree of unsaturation and consequently require lower level of antioxidants or no antioxidants. Canola oil, hydrogenated canola oil and hydrogenated/fractionated canola oil have shown particular promise. Some animal oils or fats may also be used. Other Oils Other oil families form an acceptable thixotropic fluids with the block polymers, but the thixotropic fluids formed by these oils are less preferred on the basis of other properties such as cost, flammability, compatibility with current flexible envelope material, availability, microbial susceptibility, and oxidation resistance. Examples of the properties for available Amoco "Indopol" polybutene oils are reported in Table 3: TABLE 3______________________________________ Viscosity, cSt,Product ID Molecular Wt. 40° C. Flash Point, °C.______________________________________Indopol L-14E 320 139 138Indopol L-50 420 504 138______________________________________ These low molecular weight polybutene oils create a very thick, very viscous, highly thixotropic composition. Compositions produced with polybutene oils have a slightly higher viscosity than similar compositions produced with PAO oils of comparable molecular weight, possibly due to the larger molecules interfering with the interaction of the diblock details with each other. For example, 11% of Kraton G1702 in Indopol L-14E (low molecular weight polybutene oil) results in a composition with approximately the same viscosity characteristics as a composition of 13% Kraton G1702 in Durasyn 168 (PAO). Nevertheless, even though requiring more diblock polymer, the higher molecular weight PAOs are preferable because they are less volatile and thereby increase the flash point of the system. Examples of the properties available for Agip Petroli "MixOil" dialkyl carbonate oils are described in Table 4: TABLE 4______________________________________ Viscosity, cSt,Product ID Molecular Wt. 40° C. Flash Point, °C.______________________________________MixOil MX2201 497 17.8 214MixOil MX2204 174 <17.8 N.A.______________________________________ Examples of the properties for available Shell "Carnea" paraffinic mineral oils are described in Table 5. TABLE 5______________________________________Product ID Viscosity, cSt, 40° C. Flash Point, °C.______________________________________ISO Grade 10 10 154ISO Grade 15 15 163ISO Grade 22 22 168ISO Grade 32 32 182ISO Grade 46 46 190ISO Grade 68 68 204 ISO Grade 100 100 216______________________________________ A comparison of the viscosity index of each family of oil is listed in Table 6. TABLE 6______________________________________Oil Family Viscosity Index______________________________________PAO 138Polybutene 90Dialkyl Carbonate 120Mineral 90______________________________________ The PAO family of oils demonstrated the best combination of properties of those shown in Table 6. This oil family exhibited the highest flash point and viscosity index of the group of four selected for evaluation. Published viscosity index data was not available for the vegetable oils. Viscosity variability with temperature was determined by testing vegetable oil based fluids and compositions and found to be superior to most prior art compositions. The polybutene oils from Amoco Corporation, mineral oils from Shell Corporation, and the dialkyl carbonate oils from Agip Petroli Corporation of Italy all formed compositions with excellent properties when matched with the selected diblock polymers. The Block Polymer A number of different block polymers may be used as the compatible/incompatible component of the thixotropic fluids of the present invention. The preferred diblock polymer for use with the PAO oils are thermoplastics where one block of the polymer is rigid polystyrene and the other block is soft rubber-like elastomer sold commercially by Shell Chemical Co. under the name Kraton G1701 and Kraton G1702. The preferred diblock polymers for use with the vegetable oils are sold commercially by Dexco Corp. under the name Vector 6030 and from Firestone under the name Stereon 7030A. Both Kraton G1701 and G1702 consist of a single polystyrene block on one end of the molecule and of a poly(ethylene-propylene) block on the other end and have a molecular weight of approximately 100,000. The Kraton G1702 polymer has a polystyrene content of 28% compared to 37% for the Kraton G1701 polymer. The Kraton G1702 is slightly preferred because it produces a composition having slightly lower flammability than a similar composition made with Kraton G1701. It is believed that this lower polystyrene content of Kraton G1702 polymer produces a composition having a lower flammability. The rigid polystyrene blocks of the diblock polymers have a poor affinity for and are insoluble in the selected oil (e.g., PAO, polybutene, dialkyl carbonate or mineral), while the soft (rubber-like) elastomeric poly(ethylene-propylene) blocks have an affinity for and are soluble in the oil (i.e., have a close solubility parameter). Diblock polymers having one polystyrene block and the one polybutadiene block are particularly useful with vegetable oils. Such polymers are available from Dexco and sold under the commercial name Vector 6000, 6001 and 6030, with molecular weights of 150,000, 250,000 and 145,000, respectively. A tapered diblock polymer of polystyrene and polybutadiene sold under the tradename Stereon 730A from Firestone is also useful. It is postulated that the differential in the solubility parameter compatibility of the two blocks and the oil results in micelles being formed, with the rigid polystyrene blocks clustering together into groups and the elastomeric blocks being drawn outward and essentially dissolving into the surrounding oil. The unique micellular structure of the compositions that provides the desirable thixotropic properties. The interaction/intertangling of the many elastomeric extending out from the polystyrene clusters of the micelles into the oil causes the thickening effect which turns the oil into a deformable, thixotropic fluid. Moreover, the strong affinity of the oil for the elastomeric blocks makes the composition highly resistant to separation, e.g., bleeding out of the oil from the composition. The present invention also contemplates that use of certain triblock polymers that form micelles when mixed with a compatible oil. Commercially available triblock polymers have typical block arrangement that consists of a central soft rubber-like elastomeric block flanked by two rigid polystyrene blocks. The Kraton triblock polymers can be classified into three basic types of polymers: S-B-S, S-I-S, or S-EB-S. A triblock consists of three differing blocks, or segments of identical repeating sub-units. The "S" designator stands for polystyrene, "B" stands for polybutadiene; "I" stands for polyisoprene; and "EB" stands for poly(ethylene-butylene) or in some cases poly(ethylene-propylene). Polymer micelles formed from such triblock polymers have the ability to associate with adjacent micelles through the polystyrene end blocks. One polystyrene end block may be embedded in the central clump of one micelle while the other polystyrene end block may be embedded in the central clump of an adjacent micelle. The triblock based compositions tend to have a solid, rubber or gelatin-like consistency, rather than a thin grease-like consistency. The present invention further contemplates other thixotropic fluid formed by the interaction of a major portion of a silicone oil mixed with a diblock polymer having a soft silicone polymer grafted onto a hard polystyrene block to form a micellular emulsion. The present invention also contemplates diblock polymers formed by grafting a rigid polycarbonate onto polyisoprene, polybutadiene, or poly(ethylene-propylene). A diblock polymer having a soft polyester block would form a micellular emulsion with an ester oil, and a diblock polymer having a soft polyglycol ester block would form a micellular emulsion with such a glycol ester. Selection of the compatible-incompatible components Preferable formulations require matching the selected block polymer elastomeric block with specific families of oils. Saturated elastomeric blocks (those polymers containing no double bonds between adjacent carbon atoms), such as the ethylene-butylene, or ethylene-propylene performed best with saturated oils. Unsaturated elastomeric blocks (those polymers that do contain double bonds between adjacent carbon atoms), such as the butadiene and isoprene block polymers, performed best with unsaturated oils such as the vegetable oils. One important attribute generally determining whether an oil will form a micellular emulsion is whether the solubility parameter of the oil is similar to the solubility parameter of one block of the diblock polymer and dissimilar to the other block. Solubility parameters can be calculated by, e.g., Small's or Hildebrand's methods, or using boiling points and/or surface tension, or other known methods, and are published in widely available tables. Due to the differential solubility parameters, one block of the diblock polymer will have an affinity for and tend to dissolve in the oil, while the other block will be dissimilar to and tend to be repelled by the oil. Hence, the dissimilar blocks of the diblock polymers try to congregate together while the blocks of the diblock polymers with solubility parameters similar to the oil solubility parameter will be attracted the surrounding oil. This causes the diblock polymers to organize themselves into micelles with their insoluble ends clumped together in the center and their soluble ends extending outward into the surrounding oil (similar to the way that the hydrophobic and hydrophilic ends of soap molecules behave in water). With regard to PAO oil, the solubility parameter is about 7.71-8.5 (depending on how calculated), while the solubility parameters of polystyrene and poly(ethylene-propylene) are 9.1 and 8.91, respectively. Thus, in this case, although the solubility parameters of the two blocks of the diblock polymer are fairly close, the polystyrene block is nonetheless quite dissimilar to both the poly(ethylene-propylene) block and the PAO oil (which are similar to each other), so the polystyrene blocks tend to cluster together and micelles form. Similarly, the solubility parameter of a vegetable oil (a typical configuration being a triglyceride with stearic pendant groups) is 8.85 and the complementary elastomer of polybutadiene has a solubility parameter of 8.1-8.6. The solubility of other oils such as polybutene have been calculated to be 7.42-8.02 and to be 8.38 for dialkyl carbonate oils. However, the solubility parameter is not necessarily the sole factor for determining whether a particular oil and diblock polymer will form micelles. Other characteristics of the oil and the block polymers may also be important. For example, the molecular weight of the oil also impacts on the formation and characteristics of the micellular emulsions. Generally, the higher the molecular weight of the oil, the closer the solubility parameter of the oil should match the solubility parameter of the soluble block the of the diblock polymer. The higher molecular weight of the oil tends to produce micellular emulsion grease having slightly lower viscosity. On the other hand, higher molecular weight oils are desirable because they are less volatile, have higher flash points and are less flammable. Hence, although the differential solubility parameter compatibility between one block of the diblock and the other block is a primary consideration for identifying suitable oils and diblock polymers, other factors may also need to be considered. Normally, it is desirable to select an oil that is compatible with the elastomeric block of the diblock polymers, but not the styrene block. By being compatible, the elastomeric block of the polymer will preferentially dissolve into the oil. This is thermodynamically favorable. However, it is thermodynamically unfavorable for the styrene end to accompany the elastomeric end into solution and remain in a separated, free floating configuration. The thermodynamic energy of the system can be brought into a more favorable configuration if the styrene ends of the molecules can somehow rearrange themselves so that they minimize the collective surface area in contact with the oil while maximizing the exposed collective surface area of the elastomeric ends This is easily accomplished if the molecules align themselves with the styrene ends clumping together in the center of a ball with the elastomeric tails pointing out into the oil. This can be best visualized by comparing the structure to that of a sea urchin. The diblock micelles formed are extremely small. Although the aggregate diameter is not known quantitatively, the thixotropic fluids formed by these oil/polymer systems were of a light blue shade, indicating that the micelles were probably absorbing and interfering with the blue components of visible light. The thixotropic character of the fluids are believed to be caused by the small particle interaction of these micelles. The long chains of the elastomers of one micelle interact with and entangle with elastomer chains of other micelles. Supplemental Thickener The present invention contemplates the use of supplemental particle-type thickeners to increase the viscosity of the deformable compositions and/or to modify the viscosity/shear curve of the composition to provide a more desirable viscosity profile. The supplemental thickeners are substantially insoluble in the oil/block polymer composition so that the supplemental thickener is dispersed throughout the oil/block polymer composition as small, discrete solid particles, e.g. particle sizes in the 1 to 10 micron range. Various materials may be used as supplemental thickeners including clays, silicas and insoluble organic materials such as fatty acid amides and some types of polyethylene wax, castor wax, natural and petroleum derivitized waxes. Paracin P285, reported to be N,N'-ethylene bis(12-hydroxy steramide), and AC405, reported to be and ethylene/vinyl acetate wax are preferred. Other waxes which may be used are shown in Table 7, below. TABLE 7______________________________________Wax Name Chemical Designation Manufacturer______________________________________Epolene N-15P polypropylene Eastman Chemical Co.AC680 Oxidized polyethylene Allied Signal homopolymerAC307-A Oxidized polyethylene Allied Signal homopolymerAC540 Ethylene Acrylic Acid Allied Signal copolymerAAC405-T Ethylene vinyl acetate Allied Signal copolymerAC9 polyethylene Allied Signal homopolymerAC617 polyethylene Allied Signal homopolymerEBS Crodamide Amide Croda Universal, Inc.EBO Crodamide Amide Croda Universal, Inc.Kantstik S Amide Specialty ProductsParacin P220 Amide CasChemParacin P285 Amide ChasChemThixcin R Castor wax Rheox Corp.Baragel 10 Bentonite Clay Rheox Corp.Cab-O-Sil fumed silica Cabot Corp.______________________________________ The use of wax thickeners in the compositions of the present invention provides an enhanced flame suppression characteristic which is not found when inert or solid thickeners, such as clays or silicas, are used in such compositions. The waxes change in physical state during flame ignition from a solid to a liquid to a gaseous state. This physical change is an important element in the ability of the composition to suppress ignition. These changes in physical state either absorb heat or changes the flame characteristics rendering the composition ignition resistant. Compositions containing vegetable oil based thixotropic fluids, wax-type supplemental thickeners and plastic microballoons are flame ignition resistant and will pass test similar to the Cal 117 test. Although the chemical components of such compositions are individually flammable, when these components are combined into the preferred composition, the composition becomes flame resistant. It has been found that the addition of the supplemental thickener can bolster the viscosity curves for the deformable compositions of the present invention. Compositions prepared with supplemental thickeners have improved resistance to slump, particularly after mechanical working of the composition. The vegetable oil based compositions containing supplemental thickeners also show improved viscosity stability with respect to temperature change. The Microballoons The microballoons preferably used in the formulations are discrete micro-sized particles. The microballoons constitute a discontinuous, solid phase uniformly dispersed in the thixotropic fluid which comprises the deformable component of the composition. Mixtures of different microballoon species also may be used in the practice of the invention. The size of the microballoons will preferably be within the size range of about 10 to about 300 microns. It is generally preferred to use from about 2 to about 4 percent by weight of light plastic microballoons, or about 5 to about 40 percent by weight in the case of glass microballoons. The density of the microballoons generally will be between about 0.025 and about 0.80 g/cc. Microballoons serve as density-reducing components of the compositions. Therefore, the weight of the microballoons in most cases will be lower than the combined weight of all of the other components. Although plastic microballoons are preferred, glass, phenolic, carbon, ceramic or other microballoons may be used in the compositions of the present invention. The volume of microballoons in the deformable pressure-compensating compositions affects the overall viscosity of these compositions. The maximum theoretical loading for spherical microballoons of the same size, with nearly perfect packing of the microballoons, is about 74% by volume. However, the maximum loading of the microballoons in the herein described compositions is less than this theoretical maximum, and preferably a microballoon loading is from about 40 to about 60 volume percent. For the lightest formulations, depending on microballoon density, it is preferred to load to this volumetric percentage. Weight percentages will depend on the relative densities of the microballoons and the thixotropic fluid. Plastic (i.e. copolymer or acrylic) microballoons have densities in the 0.025-0.15 g/cc range. Glass microballoons generally have densities in the 0.15-0.8 g/cc range. Phenolic microballoons have densities in the 0.15-0.25 g/cc range. Obviously, such differences can have rather significant effects on the overall densities of the final deformable compositions, which may range from about 0.30 to 0.95 g/cc. With such differences in the densities of the microballoons, the microballoon weight proportion of the overall composition can vary considerably. Plastic microballoons are generally preferred because they are considerably lighter than glass or ceramic. The specifically preferred microballoons are pre-expanded and have a PAN/PMMA (polyacrylonitrile and polymethylmethacrylate) shell surrounding a butane gas blowing agent. They are sold by Nobel Industries under the commercial name Expancel 091 DE microballoons. The plastic shell has a solubility parameter that is significantly different from the oil and both blocks of the diblock polymer, so there is little or no risk of dissolving the shell. The density of the preferred Expancel 091 DE microballoons is 0.03 g/cc, and they have an average diameter of 40 to 60 microns when expanded. The Expancel 461 DE and 551 DE are similar to the 091 DE microballoons and are also suitable for the composition, although less preferred. Glass microballoons can also be used, but with a substantial increase in weight and a dramatic reduction in the effectiveness of the preferred intumescent flame retardant. When glass microballoons are used the preferred percentage by weight of the total formulation is about 5 to 40% based upon a microballoon density of 0.20-0.40 g/cc, and the preferred percentage by volume is about 40-60%. Other glass microballoon densities are available, but are generally either too light and weak or too heavy to be of use. The Flame Retardant The preferred type of flame retardant is an intumescent flame retardant (IFR), which forms a fluffy, carbonaceous foam char as an ashy by-product when the composition is burned. The system consists of three chemical parts: a catalyst, a carbon source and a blowing agent. In the preferred embodiment, the catalyst is a phosphoric acid that has been neutralized to a salt form and polymerized into a long chain to reduce moisture effects and undesirable chemical reactions (ammonium polyphosphate or APP); the carbon source is pentaerythritol (a polyol or polyhydric alcohol); and the blowing agent, which does not take part in the charring reaction, but degrades with heat giving off ammonia, nitrogen, carbon dioxide, and/or water, is melamine formaldehyde, which is preferably an encapsulating shell surrounding the APP in order to avoid skin irritation problems. With the PAO based compositions, the preferred amount of the total IFR components is generally about 23% by weight of the formulation comprising the PAO oil, Kraton G1702 diblock polymer, and plastic microballoons. For the vegetable oils based compositions, sufficient flame retardant is used to achieve the desired level of flame resistance. Generally, for applications requiring a composition to have only resistance to ignition sources similar to the ignition source of the Cal 117 test, no flame retardant is required in the preferred vegetable oil based formulations. For applications requiring a composition with the ability to self-extinguish from flame sources similar to those used in the Cal 133 test, approximately 23% IFR is required in the preferred vegetable oil based formulations. Specific examples of various IFR components are listed in Table 8. This table lists the product name, the generic composition and the function that the component serves. There are many variations available from many different sources. TABLE 8______________________________________ FUNCTIONProduct ID Vendor Chemical Composition Cat Char Blow______________________________________Hostaflam 422 HC (1) APP XHostaflam 462 HC APP X XHostaflam 750 HC APP XAmgard ND A&W (2) Di-melamine X X PhosphateAmgard NH A&W Melamine Phosphate X XAmgard NP A&W EDAP + Melamine X XAmgard NK A&W EDAP (3) XAmgard MC A&W APP XAmgard MJ A&W Melamine X X Pyrophosphate DSM (4) Melamine di-borate XSpinflam MF Himont Proprietary X X XTHEIC BAASF Tris-hydroxy X isocyanuratePentaerythritol Various polyol XManitol Various aliphatic polyol XSorbitol Various aliphatic polyol XNH 1197 Great Lakes Proprietary X X XNH 1151 Great Lakes Proprietary X X XMAP Monsanto Mono ammonium X phosphate______________________________________ (1) Hoechst Celanese Corporation (2) Albright & Wilson Corporation (3) Ethylene diamine ammonium phosphate (4) DSM Americas Corporation Although IFRs are preferred, other flame retardants may also be used. They generally work in one of four ways: (1) they interfere with flame chemistry in the solid phase, (2) they interfere with flame chemistry in the gas phase, (3) they absorb heat, or (4) they displace oxygen. Examples of these other types of flame retardants are listed in Table 9. TABLE 9______________________________________ Function Chemical Cool InertProduct ID Vendor Composition Solid Gas ant Gas______________________________________Melamine DSM Melamine X XMelamine DSM Melamine X X XDi-borate di-borateAOM Climax Corp Ammmonium X X X octamolybdateFlamebrake US Borax Zinc borate X XZBBorax US Borax Hydrated borax X XSaytex 102 Albemarle Brominated X aromaticHBCD Albemarle Brominated X aliphaticMg Dead Sea Mg hydroxide XHydroxide BrominePyroChek Ferro Brominated X68PB polystyreneKemgard Sherwin Wm Zinc molybdate X911CEpsom Salt PQ Corp Magnesium X X sulfateBismuth Metal Specs Bismuth X XSub- sub-carbonateCarbonateHaltex 3xx Hitox Corp Alumina X trihydrateSFR 100 GE High viscosity X Silicones silicone oilBurnEx 2000 Nyacol Antimony X Corp. pentoxide______________________________________ As noted above, the IFRs unexpectedly function much more effectively when plastic microballoons are used instead of glass. Glass microballoons generally require about 33% minimum IFR material. This is theorized to be due to the glass microballoons wicking by capillary action the flammable liquid of the composition out to the flame front. Also, unlike plastic, glass microballoons do not melt and remain in the ash structure, thereby perhaps preventing the IFR from expanding and insulating the fuel from the oxygen and flame. Likewise, flame retardants based on halogenated technology work by generating gases that interfere with the flame chemistry as well as displacing oxygen. Hence, they need to burn at the flame front in order to work, and glass microballoons seem to sequester these agents too far from the flame front to be effective, while at the same time it is postulated that the glass microballoons wick the flammable liquids out to the flame front. This phenomenon may be some what overcome by the use of low melting point aliphatic halogenated compounds. A particularly effective example of this class of chemical is Saytex HBCD-LM, available from Albemarle Corp. It has been shown to melt and wick to the flame front, along with the fuel, at which point it decomposes releasing its bromine component. Other Additives A small amount of a biocide preservative, such as a paraben oil mixture, sold by ICI Sutton Labs under the name Liquipar, is preferably added to POA based compositions in order to inhibit microorganism growth. Biocide combinations which have proven successful for compositions containing vegetable oil based thixotropic fluids include methylparaben, Liquapar (which contains isopropylparaben, butyl paraben and isobutyl paraben), EDTA (ethylene ethylenedinitrilo-tetraacetic disodium salt), benzalkonium chloride and phenoxyethanol. Testing has shown that for POA based compositions, antioxidants, other than those already present in the Kraton G1702 product, are not required. For vegetable oil based compositions, it may be desired to add antioxidants, such as vitamin E, hindered phenols, secondary amines, phosphates, phosphites, and oxidized sulfur systems. Generally it is preferred to use antioxidants which have been approved for use in foods such as BHA (butylated hydroxyanisole), BHT (butylated hydroxytoluene), TBHQ (tertiary butyl hydroxyquinone), tocopherols, ascorbic acid and its esters, propyl gallate, calcium lactate, ethoxyquin and the like. The addition of minor quantities of silicone oil to vegetable oil based compositions have increased the oxidation resistance of the compositions. Other possible additives that may be used with all oil family oils include perfumes, dyes, extenders, fillers, tackifiers, UV stabilizers, and surfactants. The Mixing Process The deformable pressure-compensating compositions of the present invention are preferably prepared as follows. A desired quantity of oil is measured out. Then, an appropriate quantity of diblock polymer is crumbled into the oil, ensuring adequate vigorous agitation with a Cowles blade type disperser to avoid agglomeration of the polymer. The mixture is agitated until the oil/polymer slurry begins to thicken (approximately 30 minutes). It is then left for at least 12 hours so that the polymer can completely take up the oil. All of the other ingredients, if any, are then added, except the microballoons, and the composition is mixed thoroughly to assure complete dispersion of any powders. Finally, the microballoons are added and thoroughly mixed with a low shear ribbon blender type mixer. In the case of PAO oil based compositions, all of the above steps may be performed at room temperature. However, for vegetable oil based compositions, heat (approx. 160° F.) and substantially more agitation are preferred. The compositions based on vegetable oils and block polymers wherein a supplemental thickener (such as Paracin P-285) is used are best prepared by heating the components under conditions that melt the supplemental thickener and form a liquid mixture. The heated mixture is then passed through a colloid mill running at 20 to 25 k rpm with a gap setting of 1 to 10 mils in which it is mixed to assure dispersion of the oil, diblock polymer, wax and antioxidant. The composition leaves the colloid mill at 270° to 310° F. and is quickly cooled by passing through a chilled three roll mill. The chilling step causes the supplemental thickener to form very small solid particles in the order of 1 to 10 microns which are uniformly disperse throughout the viscous liquid oil/block polymer. The Envelope The envelope in which the deformable, pressure-compensating composition is confined may be fabricated from any flexible sheet-like material which is inert with respect to the deformable pressure-compensating composition and/or any component thereof. The materials from which the envelopes are made should also provide a complete barrier for all components of the composition. The envelopes may be formed of a variety of flexible and pliable materials known to the art, e.g., synthetic resinous materials, such as polyurethanes. Polyurethane films are useful in the practice of this invention because they possess superior softness, suppleness, and strength compared to, for example, PVC films. Polyurethanes do not contain plasticizers which may leach out over time to cause the film to harden, crack, or otherwise change in an undesirable manner. Preferably the material used to construct the envelope will be heat or radio frequency sealable to provide a substantially impervious seal which prevent leakage of any and all materials. The resinous film material also should be very flexible and/or elastomeric, both at ambient room temperatures and at the temperatures at which such pressure-compensating pads are used e.g., in the vicinity of 100° F. It also is important that the envelope material be durable and retain its flexible, pliable properties over extended periods of use. THE EXAMPLES The following examples will serve to illustrate some deformable pressure-compensating compositions within the scope of the present invention. It is understood that these examples are set forth merely for illustrative purposes and many other compositions are within the scope of the present invention. Those skilled in the art will recognize that compositions containing other quantities of material and different species of the required materials may be prepared. Example 1 The preferred composition containing the preferred PAO-based thixotropic fluid according to the present invention is given, along with preferred useful ranges, as follows: ______________________________________Ingredient Wt Percentage Range______________________________________Durasyn 168 (PAO Oil) 69.64 20 to 91Kraton G1702 Diblock Polymer 4.85 2 to 15091 DE plastic microballoons 3.00* 2 to 15Hostaflam 462 encapsulatedAmmonium Polyphosphate 14.08 5 to 30Pentaerythritol 8.23 2 to 15Liquipar (paraben biocide oil) 0.20 0.1 to 0.5______________________________________ *Approximately 55% by volume. The overall density of the composition of Example 1 is about 0.52-0.54 g/cc, and the viscosity is about 180,000 to 200,000 cps, measured using a Brookfield viscometer, spindle #7, at 20 RPMs. Example 2 Another composition containing a PAO-based thixotropic fluid according to the present invention is given, along with preferred useful ranges, as follows: ______________________________________Ingredient Wt Percentage Range______________________________________Durasyn 168 (PAO Oil) 69.99 20 to 90Kraton G1702 Diblock Polymer 3.12 2 to 15Paracin 285 (fatty acid amide 4.68 0 to 12synthetic wax)091 DE plastic microballoons 2.50* 2 to 10Hostaflam 462 encapsulatedAmmonium Polyphosphate 8.78 5 to 30Pentaerythritol 5.85 2 to 15CPVC (Chlorinated poly vinyl 4.88 0 to 20chloride plastic resin powder)Liquipar (paraben biocide oil) 0.20 0.1 to 0.5______________________________________ *Approximately 45% by volume. The overall density of the composition of Example 2 is about 0.55 g/cc, and the viscosity is 140,000 to 160,000 cps. Example 3 A composition containing a polybutene-based thixotropic fluid according to the present invention is given, along with preferred useful ranges, as follows: ______________________________________Ingredient Wt Percentage Range______________________________________Indopol L-14E (Polybutene oil) 70.25 20 to 91Kraton G1702 Diblock Polymer 4.24 2 to 15091 DE plastic microballoons 3.00* 2 to 8Hostaflam 462 encapsulatedAmmonium Polyphosphate 14.08 5 to 30Pentaerythritol 8.23 2 to 15Liquipar (paraben biocide oil) 0.20 0.1 to 0.5______________________________________ *ApproximateIy 48% by volume. The overall density of the composition of Example 3 is about 0.53 g/cc. Example 4 A composition containing a polybutene based thixotropic fluid, without flame retardant, according to the present invention is given, along with preferred useful, as follows: ______________________________________Ingredient Wt Percentage Range______________________________________Indopol L-14 (Polybutene oil) 90.25 75 to 96Kraton G1702 Diblock Polymer 5.25 2 to 15091 DE plastic microballoons 4.50* 2 to 10______________________________________ *Approximately 64% by volume. The overall density of the composition of Example 4 is about 0.43 g/cc, and the 140,000 to 160,000 cps. Example 5 A composition containing a dialkyl carbonate based thixotropic fluid according to the present invention is given, along with preferred useful ranges, as follows: ______________________________________Ingredient Wt Percentage Range______________________________________MixOil 2201 (C15-17 Dialkyl 68.71 32 to 89Carbonate Oil)Kraton G1702 Diblock Polymer 5.78 2 to 15091 DE plastic microballoons 3.00* 2 to 8Hostaflam 462 encapsulatedAmmonium Polyphosphate 14.08 5 to 30Pentaerythritol 8.23 2 to 15Liquipar (paraben biocide oil) 0.20 0.1 to 0.5______________________________________ *Approximately 48% by volume. The overall density of the composition of Example 5 is about 0.53 g/cc. Example 6 A composition (with glass microballoons) containing a corn oil-based thixotropic fluid according to the present invention is, along with preferred useful ranges, as follows: ______________________________________Ingredient Wt Percentage Range______________________________________Corn Oil 49.34 20 to 91Vector 6001 Diblock Polymer 3.08 2 to 153M K37 Glass Microballoons 24.23* 0 to 20Hostaflam 462 EncapsulatedAmmonium Polyphosphate 15.42 5 to 30Pentaerythritol 7.71 2 to 15Liquipar (paraben biocide oil) 0.25 0.1 to 0.5TBHQ Antioxidant 0.05 0.02 to 0.1______________________________________ *Approximately 40% by volume. A lower level of glass microballoons was used to keep the viscosity at the desired level. The overall density of the composition of Example 6 is about 0.74 g/cc, and the viscosity is about 180,000-200,000 cps, measured using a Brookfield viscometer, spindle #7, at 20 RPMs. Example 7 A composition (with plastic microballoons) containing a corn oil-based thixotropic fluid according to the present invention is given, along with preferred useful ranges, as follows: ______________________________________Ingredient Wt Percentage Range______________________________________Corn Oil 85.76 30 to 95Vector 6001 Diblock Polymer 5.40 2 to 15091 DE plastic microballoons 2.21* 0-10Hostaflam 462 EncapsulatedAmmonium Polyphosphate 4.07 2 to 30Pentaerythritol 2.31 1 to 15Liquipar (paraben biocide oil) 0.25 0.1 to 0.5TBHQ Antioxidant 0.05 0.02 to 0.1______________________________________ *Approximately 42% by volume. The overall density of the composition of Example 7 is about 0.49 g/cc, and the viscosity is about 180,000-200,000 cps, measured using a Brookfield viscometer, spindle #7, at 20 RPMs. Example 8 A preferred composition containing a canola oil-based thixotropic fluid according to the present invention is given, along with preferred useful ranges, as follows: ______________________________________Ingredient Wt Percentage______________________________________Canola Oil 84%Paracin P285 5%Vector 6030 Diblock Polymer 5%091 DE plastic microballoons 5%*Composite biocide 1%TBHQ Antioxidant 0.05______________________________________ *Approximately 63% by volume. The overall density of the formulation Example 8 is about 0.40 g/cc, and the viscosity is about 180,000-200,000 cps, measured using a Brookfield viscometer, spindle #7, at 20 RPMs. Example 9 A most preferred composition containing a canola oil-based thixotropic fluid according to the present invention is given, along with preferred useful ranges, as follows: ______________________________________Ingredient Wt Percentage______________________________________Hydrogenated/Fractionated Canola Oil 84%Paracin P285 4.5%Silicone Oil 0.5%Vector 6030 Diblock Polymer 5%091 DE plastic microballoons 5%*Composite biocide 1%TBHQ Antioxidant 0.05______________________________________ *Approximately 63% by volume. The overall density of the formulation Example 9 is about 0.4 g/cc, and the viscosity is about 180,000-200,000 cps, measured using a Brookfield viscometer, spindle #7, at 20 RPMs. Example 10 A composite biocide formulation which has proven effective, especially in vegetable oil formulations, and which was used in the formulations of Examples 8, 9, 11, 13 and 14, is as follows: ______________________________________Biocide Concentration______________________________________methyl paraben 20%Liqupar oil 20%isopropyl parabenbutyl parabenisobutyl parabenEDTA (ethylenedinitrilo-tetraacetic 20%disodium salt)benzalkonium chloride 10%phenoxyethanol 30%______________________________________ Example 11 Another composition containing a canola oil-based thixotropic fluid according to the present invention is as follows: ______________________________________Ingredient Wt Percentage______________________________________Hydrogenated/Fractionated canola oil 81.5%Paracin P285 5%Silicone oil 2%Vector 6030 Diblock Polymer 5%091 DE plastic microballoons 5%*Antioxidant (see Example 12, below) <0.5%Composite biocide 1%______________________________________ *Approximately 63% by volume. The overall density of the formulation Example 11 is about 0.40 g/cc. Example 12 The several antioxidants listed below were tested for use in compositions containing hydrogenated/fractionated canola oil-based thixotropic fluids according to the present invention. Each of the antioxidants are approximately interchangeable in the compositions based on the hydrogenated/fractionated canola oil fluids. ______________________________________Antioxidant Preferred amount Useable range______________________________________BHA/BHT 0.15% 0.05-0.3%MT-70, tocopherols, UOP 0.18% 0.05-0.3%MT-AP, tocopherols & 0.06% 0.02-0.2%ascorbyl palmitate, UOPTBHQ 0.01% 0.005-0.1%______________________________________ Example 13 Another composition containing a canola oil-based thixotropic fluid according to the present invention is as follows: ______________________________________Ingredient Wt Percentage______________________________________Hydrogenated/Fractionated canola oil 72%AC405 T, Allied Signal 6%Silicon Oil 10%Vector 6030 Diblock Polymer 6%091 DE plastic microballoons 4.5%*Antioxidant (see Example 12) <0.5%Composite biocide 1%______________________________________ *Approximately 63% by volume. The overall density of the formulation Example 13 is about 0.40 g/cc. Example 14 Another composition containing a canola oil-based thixotropic fluid according to the present invention is as follows: ______________________________________Ingredient Wt Percentage______________________________________Hydrogenated/Fractionated canola oil 72.25%AC405 T, Allied Signal 6%Silicon Oil 10%Vector 6030 Diblock Polymer 6%091 DE plastic microballoons 4.25%*Antioxidant (see Example 12) <0.5%Composite biocide 1%______________________________________ *Approximately 63% by volume. The overall density of the formulation Example 14 is about 0.40 g/cc. Test Results The following are separation test results comparing compositions substantially as disclosed in U.S. Pat. No. 4,588,229 to Jay and U.S. Pat. No. 5,362,543 to Nickerson with the PAO composition of Example 1, according to the present invention. TABLE 10______________________________________Test Jay '229 Nickerson '543Conditions Comp. comp. PAO comp______________________________________55° C., 3 days-Large 28 days-Small 3 mo-No3 Months (1) qty oil qty oil oil sep. Sep (2) Sep.65° C., 3 days-Large 28 days-Small 3 mo-No3 Months qty oil qty oil oil sep. Sep Sep.79° C., 1 day-Large 14 days-Small 3 mo-No3 Months qty oil qty oil oil sep. (3) Sep Sep.0 to 55° C., 3 days-Large No sep. No sep.30 cycles, qty oil observed observed24 hr/cycle SepBlender Test (4) Den = +7.0% Den = +4.8% Den = +2.8% Vis = -22% Vis = -28% Vis = -4.2%Cal 133 Flame No Self -0.5% - 4 -3.2% - 4Test (5) Extinguish minutes, minutes, 15 seconds 24 seconds______________________________________ (1) Test Criteria: Small quantities of separation are acceptable. Approximately 0.5% of total material weight. (2) Time until first observed oil separation. (3) Test extended to 1 year. No oil separation. No change in viscosity. N hardening of material. No color change. (4) Test performed using a Sunbeam Mixmaster Model #2360, or equivalent blender, with standard beater bars, speed setting at lowest on dial. Sample size approximately 12 fl oz. Test duration is 8 hours continuous run. Comparative test results only. Looking for minimal change in viscosity and density. Den = Density change. Vis = Viscosity change. (5) 10% max weight loss. Test duration: 60 minutes. Weight loss and time to extinguish reported. The compositions of the present invention are superior to prior art products for the following reasons: a) The composition of the present invention is stable in that it does not significantly separate when exposed to body temperatures of about 95° F. to 100° F. for extended periods. (i.e., 6 months or more). b) The composition of the present invention does not pose a significant skin sensitization or irritation potential. c) The composition of the present invention has a much lower flammability when tested by the Cal 133 requirements or other relevant flame tests. d) The composition of the present invention has a much higher viscosity index i.e. the viscosity in stable over a range of temperatures, as compared to prior art compositions. e) The composition of the present invention does not stiffen to unacceptably high viscosities when chilled to low temperatures (40° F. approximate). f) When placed into a bladder and cycled repeatedly through a simulated seat cushion use test (mechanical "butt" test), the composition of the present invention will not form any evidence of hard lumps. g) When placed into a seat cushion bladder and weighted with a static weight for long periods of time (simulating long sitting use by an inactive user), the composition of the present invention will not form any evidence of hard lumps. h) The composition of the present invention has a low micro-organism growth potential and thereby has a low tendency to support the growth of micro-organisms such as mold and bacteria. i) The composition of the present invention has a high LD50 threshold (low risk of poisoning upon ingestion). j) No ingredients of the composition leach from or evaporate through the urethane film which is used for the envelope. k) No ingredients of the composition are chemically reactive with the urethane film used for the envelope. The forms of invention shown and described herein are to be considered only as illustrative. It will be apparent to those skilled in the art that numerous modifications may be made therein without departing from the spirit of the invention and the scope of the appended claims.

4y

RELATED APPLICATIONS The present invention is a continuing application of co-pending U.S. patent application Ser. No. 09/609,487, which is assigned to the same assignee as the current application, entitled “High Storage Capacity, Fast Kinetics, Long Cycle Life, Hydrogen Storage Alloys”, filed Jul. 5, 2000 now U.S. Pat. No. 6,491,866 which is a Continuation-in-Part of Ser. No. 09/435,497 filed Nov. 6, 1999 now U.S. Pat. No. 6,193,929, the disclosure of which is hereby incorporated by reference. FIELD OF THE INVENTION The instant invention relates generally to revolutionary new hydrogen storage alloys that are able, for the first time to realistically use the most ubiquitous, ultimate source of fuel, hydrogen. More specifically the instant invention relates to hydrogen storage alloys that not only are capable of storing on the order of 7 weight % hydrogen, but are capable of storing at least 80% of their maximum capacity within 10 minutes are and have a cycle life of at least 500 cycles without loss of capacity or kinetics. BACKGROUND The instant patent application for describes hydrogen storage alloys, useful for a hydrogen-based economy, which have high storage capacity, excellent kinetics and long cycle life. An infrastructure system for such a hydrogen based economy, is the subject of copending U.S. application Ser. No. 09/444,810, entitled “A Hydrogen-based Ecosystem” filed on Nov. 22, 1999 (the '810 application), which is hereby incorporated by reference. This infrastructure, in turn, is made possible by alloys such as the instant hydrogen storage alloy that have surmounted the chemical, physical, electronic and catalytic barriers that have heretofore been considered insoluble. Other hydrogen storage alloys which are useful in such an infrastructure are fully described in copending U.S. patent application Ser. No. 09/435,497, entitled “High Storage Capacity Alloys Enabling a Hydrogen-based Ecosystem”, filed on Nov. 6, 1999 (“the '497 application”), which is hereby incorporated by reference. The '497 application relates to alloys which solve the unanswered problem of having sufficient hydrogen storage capacity with exceptionally fast kinetics to permit the safe and efficient storage of hydrogen to provide fuel for a hydrogen based economy, such as powering internal combustion engine and fuel cell vehicles. In the '497 application the inventors for the first time disclosed the production of Mg-based alloys having both hydrogen storage capacities higher than about 6 wt. % and extraordinary kinetics. This revolutionary breakthrough was made possible by considering the materials as a system and thereby utilizing chemical modifiers and the principles of disorder and local order, pioneered by Stanford R. Ovshinsky, in such a way as to provide the necessary catalytic local environments, and at the same time designing bulk characteristics for storage and high rate charge/discharge cycling. In other words, these principles allowed for tailoring of the material by controlling the particle and grain size, topology, surface states, catalytic activity, microstructure, and total interactive environments for extraordinary storage capacity. The combination of the '810 and the '497 applications solves the twin basic barriers which have held back the ubiquitous use of hydrogen: 1) storage capacity; and 2) infrastructure. With the use of the alloys of the '497 application, hydrogen can be shipped safely by boats, barges, trains, trucks, etc. when in solid form. However, the hydrogen infrastructure described in the '810 application requires careful thermal management and efficient heat utilization throughout the entire system. The instant invention makes the necessary heat transfer between the subsystems of the infrastructure simple, efficient, and economic. As the world's population expands and its economy increases, the atmospheric concentrations of carbon dioxide are warming the earth causing climate change. However, the global energy system is moving steadily away from the carbon-rich fuels whose combustion produces the harmful gas. For nearly a century and a half, fuels with high amounts of carbon have progressively been replaced by those containing less. In the United States, it is estimated, that the trend toward lower-carbon fuels combined with greater energy efficiency has, since 1950, reduced by about half the amount of carbon spewed out for each unit of economic production. Thus, the decarbonization of the energy system is the single most important fact to emerge from the last 20 years of analysis of the system. It had been predicted that this evolution will produce a carbon-free energy system by the end of the 21 st century. The instant invention helps to greatly shorten that period. In the near term, hydrogen will be used in fuel cells for cars, trucks and industrial plants, just as it already provides power for orbiting spacecraft. But ultimately, hydrogen will also provide a general carbon-free fuel to cover all fuel needs. FIG. 1, taken from reliable industrial sources, is a graph demonstrating society's move toward a carbon-free environment as a function of time starting with the use of wood in the early 1800s and ending in about 2010 with the beginning of a “hydrogen” economy. In the 1800s, fuel was primarily wood in which the ratio of hydrogen to carbon was about 0.1. As society switched to the use of coal and oil, the ratio of hydrogen to carbon increased first to 1.3 and then to 2. Currently, society is inching closer to the use of methane in which the hydrogen to carbon ratio is further increased to 4 (methane has serious problems with safety, cost and infrastructure). However, the ultimate goal for society is to employ a carbon-free fuel, i.e., the most ubiquitous of elements, pure hydrogen. The obstacle has been the lack of solid state storage capacity and infrastructure. The inventors of the '497 and the '810 applications have made this possible by inventing a 7% storage material (7% is an umoptimized fugure and will be increased along with better kinetics) with exceptional absorption/desorption kinetics, i.e. at least 80% charge in less than 2 minutes and an infrastructure to use these storage alloys. These alloys allow for the first time, a safe, high capacity means of storing, transporting and delivering pure hydrogen. Hydrogen is the “ultimate fuel.” It is inexhaustible. Hydrogen is the most plentiful element in the universe (over 95% of all matter). Hydrogen can provide a clean source of energy for our planet and can be produced by various processes which split water into hydrogen and oxygen. The hydrogen can then be stored and transported in solid state form. While the world's oil reserves are depletable, the supply of hydrogen remains virtually unlimited. Hydrogen, which can be produced from coal, natural gas and other hydrocarbons, is preferably formed via electrolysis of water, more preferably using energy from the sun (see U.S. Pat. No. 4,678,679, the disclosure of which is incorporated herein by reference.) However, hydrogen can also be produced by the electrolysis of water using any other form of economical energy (e.g., wind, waves, geothermal, hydroelectric, nuclear, etc.) Furthermore, hydrogen, is an inherently low cost fuel. Hydrogen has the highest density of energy per unit weight of any chemical fuel and is essentially non-polluting since the main by-product of “burning” hydrogen is water. Thus, hydrogen can be a means of solving many of the world's energy related problems, such as climate change, pollution, strategic dependancy on oil, etc., as well as providing a means of helping developing nations. While hydrogen has wide potential application as a fuel, a major drawback in its utilization, especially in mobile uses such as the powering of vehicles, has been the lack of an acceptable lightweight hydrogen storage medium. Storage of hydrogen as a compressed gas involves the use of large and heavy vessels. Additionally, large and very expensive compressors are required to store hydrogen as a compressed gas and compressed hydrogen gas is a very great explosion/fire hazzard. Hydrogen also can be stored as a liquid. Storage as a liquid, however, presents a serious safety problem when used as a fuel for motor vehicles since hydrogen is extremely flammable. Liquid hydrogen also must be kept extremely cold, below −253° C., and is highly volatile if spilled. Moreover, liquid hydrogen is expensive to produce and the energy necessary for the liquefaction process is a major fraction of the energy that can be generated by burning the hydrogen. Another drawback to storage as a liquid is the costly losses of hydrogen due to evaporation, which can be as high as 5% per day. For the first time, storage of hydrogen as a solid hydride, using the atomically engineered alloys of the '497 application can provide a greater percent weight storage than storage as a compressed gas or a liquid in pressure tanks. Also, hydrogen storage in a solid hydride is safe and does not present any of the hazard problems that hydrogen stored in containers as a gas or a liquid does, because hydrogen, when stored in a solid hydride form, exists in it's lowest free energy state. In addition to the problems associated with storage of gaseous or liquid hydrogen, there are also problems associated with the transport of hydrogen in such forms. For instance transport of liquid hydrogen will require super-insulated tanks, which will be heavy and bulky and will be susceptible to rupturing and explosion. Also, a portion of the liquid hydrogen will be required to remain in the tanks at all times to avoid heating-up and cooling down of the tank which would incur big thermal losses. As for gaseous hydrogen transportation, pressurized tankers could be used for smaller quantities of hydrogen, but these too will be susceptible to rupturing and explosion. For larger quantities, a whole new hydrogen pipeline transportation system would need to be constructed or the compressor stations, valves and gaskets of the existing pipeline systems for natural gas will have to be adapted and retrofitted to hydrogen use. This assumes, of course, that the construction material of these existing pipelines will be suited to hydrogen transportation. A high hydrogen storage capacity per unit weight of material is an important consideration in applications where the hydride does not remain stationary. A low hydrogen storage capacity relative to the weight of the material reduces the mileage and hence the range of the vehicle making the use of such materials impractical. A low desorption temperature (in the neighborhood of 300° C.) is desirable to reduce the amount of energy required to release the hydrogen. Furthermore, a relatively low desorption temperature to release the stored hydrogen is necessary for efficient utilization of the available exhaust heat from vehicles, machinery, or other similar equipment. Good reversibility is needed to enable the hydrogen storage material to be capable of repeated absorption-desorption cycles without significant loss of its hydrogen storage capabilities. Good kinetics are necessary to enable hydrogen to be absorbed or desorbed in a relatively short period of time. Resistance to poisons to which the material may be subjected during manufacturing and utilization is required to prevent a degradation of acceptable performance. The prior art metallic host hydrogen storage materials include magnesium, magnesium nickel, vanadium, iron-titanium, lanthanum pentanickel and alloys of these metals others. No prior art material, however, has solved the aforementioned problem which would make it suitable for a storage medium with widespread commercial utilization which can revolutionize the propulsion industry and make hydrogen a ubiquitous fuel. Thus, while many metal hydride systems have been proposed, the Mg systems have been heavily studied since Mg can store over 7 weight % of hydrogen. While magnesium can store large amounts of hydrogen, its has the disadvantage of extremely slow kinetics. For example, magnesium hydride is theoretically capable of storing hydrogen at approximately 7.6% by weight computed using the formula: percent storage=H/H+M, where H is the weight of the hydrogen stored and M is the weight of the material to store the hydrogen (all storage percentages hereinafter referred to are computed based on this formula). Unfortunately, despite high storage capacity, prior art materials were useless because discharge of the hydrogen took days. While a 7.6% storage capacity is ideally suited for on board hydrogen storage for use in powering vehicles, it requires the instant invention to form Mg-based alloys operating on principles of disorder to alter previously unuseable materials and make them commercially acceptable for widespread use. Magnesium is very difficult to activate. For example, U.S. Pat. No. 3,479,165 discloses that it is necessary to activate magnesium to eliminate surface barriers at temperatures of 400° C. to 425° C. and 1000 psi for several days to obtain a reasonable (90%) conversion to the hydride state. Furthermore, desorption of such hydrides typically requires heating to relatively high temperatures before hydrogen desorption begins. The aforementioned patent states that the MgH 2 material must be heated to a temperature of 277° C. before desorption initiates, and significantly higher temperatures and times are required to reach an acceptable operating output. Even then, the kinetics of pure Mg are unacceptable, i.e., unuseable. The high desorption temperature makes the prior art magnesium hydride unsuitable. Mg-based alloys have been considered for hydrogen storage also. The two main Mg alloy crystal structures investigated have been the A 2 B and AB 2 alloy systems. In the A 2 B system, Mg 2 Ni alloys have been heavily studied because of their moderate hydrogen storage capacity, and lower heat of formation ('64 kJ/mol) than Mg. However, because Mg 2 Ni has the possibility of a storage capacity of up to 3.6 wt. % hydrogen, researchers have attempted to improve the hydrogenation properties of these alloys through mechanical alloying, mechanical grinding and elemental substitutions. However, 3.6 wt. % is not nearly high enough and the kinetics are likewise insufficient. More recently, investigators have attempted to form MgNi 2 type alloys for use in hydrogen storage. See Tsushio et al, Hydrogenation Properties of Mg-based Laves Phase Alloys, Journal of Alloys and Compounds, 269 (1998), 219-223. Tsushi et al. determined that no hydrides of these alloys have been reported, and they did not succeed in modifying MgNi 2 alloys to form hydrogen storage materials. Finally, the instant inventors have worked on high Mg content alloys or elementally modified Mg. For instance, in U.S. Pat. Nos. 5,976,276 and 5,916,381, Sapru, et al have produced mechanically alloyed Mg—Ni—Mo and Mg—Fe—Ti materials containing about 75 to 95 atomic percent Mg, for thermal storage of hydrogen. These alloys are formed by mixing the elemental ingredients in the proper proportions in a ball mill or attritor and mechanically alloying the materials for a number of hours to provide the mechanical alloy. While these alloys have improved storage capacities as compared with Mg 2 Ni alloys, they have low plateau pressures. Another example of modified high Mg content alloy is disclosed in U.S. Pat. No. 4,431,561 ('561) to Ovshinsky et al., the disclosure of which is hereby incorporated by reference. In the '561 patent, thin films of high Mg content hydrogen storage alloys were produced by sputtering. While this work was remarkable in applying fundamental principles to drastically improve the storage capacities, it was not until the invention described herein that all necessary properties of high storage capacity, good kinetics and good cycle life were brought together. In U.S. Pat. No. 4,623,597 (“the '597 patent”), the disclosure of which is incorporated by reference, one of the present inventors, Ovshinsky, described disordered multicomponent hydrogen storage materials for use as negative electrodes in electrochemical cells for the first time. In this patent, Ovshinsky describes how disordered materials can be tailor-made to greatly increase hydrogen storage and reversibility characteristics. Such disordered materials are formed of one or more of amorphous, microcrystalline, intermediate range order, or polycrystalline (lacking long range compositional order) wherein the polycrystalline material may include one or more of topological, compositional, translational, and positional modification and disorder, which can be designed into the material. The framework of active materials of these disordered materials consist of a host matrix of one or more elements and modifiers incorporated into this host matrix. The modifiers enhance the disorder of the resulting materials and thus create a greater number and spectrum of catalytically active sites and hydrogen storage sites. The disordered electrode materials of the '597 patent were formed from lightweight, low cost elements by any number of techniques, which assured formation of primarily non-equilibrium metastable phases resulting in the high energy and power densities and low cost. The resulting low cost, high energy density disordered material allowed such Ovonic batteries to be utilized most advantageously as secondary batteries, but also as primary batteries and are used today worldwide under license from the assignee of the subject invention. Tailoring of the local structural and chemical order of the materials of the '597 patent was of great importance to achieve the desired characteristics. The improved characteristics of the anodes of the '597 patent were accomplished by manipulating the local chemical order and hence the local structural order by the incorporation of selected modifier elements into a host matrix to create a desired disordered material. The disordered material had the desired electronic configurations which resulted in a large number of active sites. The nature and number of storage sites was designed independently from the catalytically active sites. Multiorbital modifiers, for example transition elements, provided a greatly increased number of storage sites due to various bonding configurations available, thus resulting in an increase in energy density. The technique of modification especially provides non-equilibrium materials having varying degrees of disorder provided unique bonding configurations, orbital overlap and hence a spectrum of bonding sites. Due to the different degrees of orbital overlap and the disordered structure, an insignificant amount of structural rearrangement occurs during charge/discharge cycles or rest periods therebetween resulting in long cycle and shelf life. The improved battery of the '597 patent included electrode materials having tailor-made local chemical environments which were designed to yield high electrochemical charging and discharging efficiency and high electrical charge output. The manipulation of the local chemical environment of the materials was made possible by utilization of a host matrix which could, in accordance with the '597 patent, be chemically modified with other elements to create a greatly increased density of catalytically active sites for hydrogen dissociation and also of hydrogen storage sites. The disordered materials of the '597 patent were designed to have unusual electronic configurations, which resulted from the varying 3-dimensional interactions of constituent atoms and their various orbitals. The disorder came from compositional, positional and translational relationships of atoms. Selected elements were utilized to further modify the disorder by their interaction with these orbitals so as to create the desired local chemical environments. The disorder described in the '597 patent can be of an atomic nature in the form of compositional or configurational disorder provided throughout the bulk of the material or in numerous regions of the material. The disorder also can be introduced into the host matrix by creating microscopic phases within the material which mimic the compositional or configurational disorder at the atomic level by virtue of the relationship of one phase to another. For example, disordered materials can be created by introducing microscopic regions of a different kind or kinds of crystalline phases, or by introducing regions of an amorphous phase or phases, or by introducing regions of an amorphous phase or phases in addition to regions of a crystalline phase or phases. The interfaces between these various phases can provide surfaces which are rich in local chemical environments which provide numerous desirable sites for electrochemical hydrogen storage. The differences between chemical and thermal hydrides are fundamental. The thermal hydride alloys of the present inventions have been designed as a distinct class of materials with their own basic problems to be solved, which problems as shown in the following Table 1 are antithetical to those to be solved for electrochemical systems. These same attributes have not, until now, been achieved for thermal hydrogen storage alloys. Therefore, there has been a strong felt need in the art for high capacity, low cost, light weight thermal hydrogen storage alloy materials having exceptionally fast kinetics. TABLE 1 Electrochemical Gas Phase (Thermal) Hydrogen Hydrogen Storage Storage Material Material Mechanism H 2 O molecule splits H 2 dissociates at the material surface Environment Alkaline oxidizing H 2 gas - very environment susceptible (KOH electrolyte) to poisoning by oxygen (inoperative in presence of KOH) Kinetics Hydrogen Hydrogen storage storage/release anywhere from 20° C. to at room temperature 100° C. Thermodynamics Specific range of M—H bond strength of useful any degree is M—H bond strength acceptable Thermal Small effect Large effect Conductivity Electrical Large effect Small effect Conductivity Chemical M + H 2 O + e − ⇄ H 2 (g) ⇄ 2H Reaction MH + OH − As alluded to, above, cycle life of a hydrogen storage alloy material is very important for commercial utilization of the alloy. Cycle life of powdered Mg has been, prior to the subject invention, another one of its deficiencies. Specifically, it has been noted in the prior art that even Mg powder loses it's capacity and kinetics during hydriding/dehydriding cycling after only 40 cycles or so. This loss of capacity and kinetics is due to sintering of the Mg particles during the required high temperature cycling, and the formation of a large mass of hydrogen. For commercial applications this is not nearly long enough and at least an order-of-magnitude longer cycle life is minimally needed. Thus there is a strong-felt-need in the art for a hydrogen storage alloy which has a high storage capacity, good kinetics and a long cycle life without loss of either capacity or kinetics. SUMMARY OF THE INVENTION The instant invention provides for high capacity, low cost, light weight thermal hydrogen storage alloy materials having fast kinetics in the form of a magnesium based hydrogen storage alloy powder. These alloys, for the first time make it feasible to use solid state storage and delivery of hydrogen to power a hydrogen based economy, and particularly to power mobile energy consumer applications such as internal combustion engine or fuel cell vehicles. The alloy contains greater than about 90 weight % magnesium and has a) a hydrogen storage capacity of at least 6 weight %; b) absorption kinetics such that the alloy powder absorbs 80% of it's total capacity within 10 minutes at 300° C.; c) a cycle life of at least 500 cycles without loss of capacity or kinetics. More preferably the alloy powder has a hydrogen storage capacity of at least 6.5 weight % and most preferably at least 6.9 weight %. Also, the alloy powder more preferably absorbs 80% of it's total capacity within 5 minutes at 300° C. and most preferably within 1.5 minutes. The material more rpeferably has a cycle life of at least 650 and most preferably at least 1000 cycles without loss of kinetics or capacity. Modifier elements added to the magnesium to produce the alloys mainly include Ni and Mm (misch metal) and can also include additional elements such as Al, Y and Si. Thus the alloys will typically contain 0.5-2.5 weight % nickel and about 1.0-4.0 weight % Mm (predominantly contains Ce and La and Pr). The alloy may also contain one or more of 3-7 weight % Al, 0.1-1.5 weight % Y and 0.3-1.5 weight % silicon. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a graph having time plotted on the abscissa and the H/C ratio plotted on the ordinate, said graph demonstrating the movement of society toward carbon-free sources of fuel; FIG. 2 is an absorption plot of stored hydrogen versus time for an alloy material of the instant invention for cycles 50 and 650 , specifically showing that alloy materials of the instant invention have virtually identical hydrogen storage capacity and absorption kinetics at cycle 650 as they do at cycle 50 ; FIG. 3 is a graph of the Pressure Composition Temperature (PCT) curves of alloy FC-10 at 3 different temperatures; FIG. 4 is a graph of the PCT curves of alloy FC-76 at 3 different temperatures; FIG. 5 is a plot of the absorption kinetics of the FC-76 alloy, specifically plotted is weight % hydrogen absorption versus time for 3 different temperatures; FIG. 6 is a plot of the desorption kinetics of the FC-76 alloy specifically plotted is weight % hydrogen desorption versus time for 3 different temperatures; FIG. 7 is a plot of the absorption kinetics of the FC-86 alloy specifically plotted is weight % hydrogen desorption versus time for 3 different temperatures; FIG. 8 is a plot of the absorption kinetics of FC-76 alloy powders having two different particle sizes; FIG. 9 shows an embodiment of the instant invention where a support means bonded with the hydrogen storage alloy material is spirally wound into a coil; FIG. 10 shows an alternate embodiment of the instant invention where a support means bonded with the hydrogen storage alloy material is assembled as a plurality of stacked disks; FIG. 11, shows a schematic representation of a hydrogen gas supply system which utilizes the alloy of the instant invention for powering an internal combustion engine vehicle; and FIG. 12, shows a schematic representation of a hydrogen gas supply system which utilizes the alloy of the instant invention for powering for a fuel cell vehicle. DETAILED DESCRIPTION OF THE INVENTION As discussed above, Mg stores large amounts of hydrogen. However, the kinetics of hydrogen storage in pure Mg are less than desirable. That is, while pure Mg can store upwards of 7.6 wt. % hydrogen, the Mg—H bond is very strong (75 kJ/mol) making release of the stored hydrogen difficult and therefore pure Mg is not a commercially viable hydrogen storage material. Thus, Mg alone is not sufficient, but utilizing the principle of disorder and local order, compositional (chemically induced) and structural disorder (rapid quench) can be used to create a different distribution of elements. This breakthrough has been made possible by examining the materials as a system and by utilizing chemical modifiers and the principles of disorder and local order, pioneered by Stanford R. Ovshinsky (one of the instant inventors), in such a way as to provide the necessary local order environments for storage. These principles allow for tailoring of the material by controlling the particle size, topology, surface states, catalytic ability (including catalitic sites and surface area), microstructure, nucleation and growth rate of crystallites both on the surface and in the bulk, and storage capacity both structural and interstitial. Specifically, small particles have unique properties that bridge the gap between crystalline and amorphous solids, i.e. small geometry gives rise to new physics. It is to be noted that 50 Angstrom particles are “mostly surface,” thereby giving rise to new topologies and unusual bonding configurations. Also, 21% of all atoms in a 50 Angstrom particle are on the surface and another 40% are within one atom of the surface. Thus compositional disorder in multi-element micro-alloys is large in small particles, e.g. in a 50 Angstrom particle, each element in a 10 element alloy will show 3% variation in concentration just due to statistics. With such small particles, quantum confinement effects are apparent and band structure effects are disturbed. The instant inventors have found that, by applying the principles of atomic engineering and tailoring of the local environment, magnesium can be modified to store more than 6 wt. % hydrogen, with significantly increased kinetics which allows for economic recovery of the stored hydrogen. The increased kinetics allows for the release of hydrogen at lower temperatures, thus increasing the utility of metal hydride storage in hydrogen based energy systems. Thus the instant alloys provide commercially viable, low cost, low weight hydrogen storage materials. In general the alloys contain greater than about 90 weight % magnesium, and contain at least one modifier element. The at least one modifier element creates a magnesium based alloy which have a cycle life of at least 500 cycles without loss of either kinetics or storage capacity. More preferably the materials have a cycle life of at least 650 cycles and most preferably they have a cycle life of at least 1000 cycles. The alloys are capable of storing at least 6 weight % hydrogen. More preferably the modified alloys are capable of storing at least 6.5 weight % hydrogen and most preferably the modified alloy stores at least 6.9 weight % hydrogen. The alloys are also capable of absorbing at least 80% of the full storage capacity of hydrogen in under 10 minutes at 300° C., more preferably within under 5 minutes and most preferably in under 1.5 minutes. The modifier elements mainly include Ni and Mm (misch metal) and can also include additional elements such as Al, Y and Si. Thus the alloys will typically contain 0.5-2.5 weight % nickel and about 1.0-4.0 weight % Mm (predominantly contains Ce and La and Pr). The alloy may also contain one or more of 3-7 weight % Al, 0.1-1.5 weight % Y and 0.3-1.5 weight % silicon. A few examples will help to illustrate the instant invention. EXAMPLE 1 A modified Mg alloy having the designation FC-10 was made which has the composition: 91.0 wt. % Mg, 0.9 wt. % Ni, 5.6 wt. % Al, 0.5 wt. % Y and 2.0 at % Mm. The individual raw alloying elements were mixed in a glove box. The mixture was placed in a graphite crucible and the crucible was placed in a furnace. The crucible had a 2.0 mm boron nitride orifice at the bottom thereof which is plugged by a removable boron nitride rod. The furnace was pumped down to very low pressure and purged three times with argon. The argon pressure withing the furnace was brought up to 1 psi and kept at this pressure as the crucible was heated to 600° C. Once the melt was ready, the boron nitride rod was lifted and argon was injected into the furnace under pressure. The molten alloy flowed out of the graphite crucible through the boron nitride orifice and onto a non-water-cooled, horizontally spinning, copper wheel. The wheel, which spins at about 1000 rpm, solidifies the molten alloy into particles which then bounce off a water-cooled copper cap which covers the spinning wheel, and drop into a stainless steel pan where they gradually cool. Five grams of the solidified alloy flakes were mixed with 100 mg of graphite grinding aid. The mixture was mechanically ground for 3 hours. The ground alloy was then classified by sieving to recover material having a particle size of between 30 and 65 microns. This alloy has a storage capacity of about 6.5 wt. % hydrogen and absorbs 80% of the maximum capacity in less than 5 minutes at a temperature of about 300° C. Other details of the alloy properties are presented below. EXAMPLE 2 A modified Mg alloy having the designation FC-76 was made which has a composition: 95.6 wt. % Mg, 1.6 wt. % Ni, 0.8 wt. % Si and 2.0 wt % Mm. The alloy was formed in the same manner as Example 1, however, the furnace temperature was 850° C. and the orifice size was 2.5 mm. This alloy has a storage capacity of about 6.9 wt. % hydrogen and absorbs 80% of the maximum capacity in less than 1.5 minutes at a temperature of about 300° C. Other details of the alloy properties are presented below. EXAMPLE 3 A modified Mg alloy having the designation FC-86 was made which has a composition: 95 wt. % Mg, 2 wt. % Ni and 3.0 wt % Mm. The alloy was formed in the same manner as Example 1, however, the furnace temperature was 750° C. and the wheel speed was 1400 rpm. This alloy has a storage capacity of about 7 wt. % hydrogen and absorbs 80% of the maximum capacity in less than 2.3 minutes at a temperature of about 275° C. Other details of the alloy properties are presented below. The alloys of the instant invention are unique in their combination of high storage capacity and excellent absorption/desorption kinetics. The instant inventors have found that a combination of both alloy composition and particle size of the hydrogen storage material have a significant effect on the kinetics. That is, the instant inventors have found that the kinetics of the material (regardless of specific composition) improve with decreasing particle size. Specifically, the instant inventors have found that materials having a particle size of between about 30 and 70 microns are the most useful. This particle size gives excellent kinetics while still being capable of being manufactured. Increasing particle size eases manufacturing, but reduces the kinetics of the material from the optimal, while decreasing particle size is nearly impossible because of the high ductility of these Mg based alloys. In fact, the use of gas atomization may be required in industry to manufacture bulk quantities of the particulate alloy specifically because the alloys are too ductile to be ground efficiently. It is significant to note that the kinetics and capacity of the alloys of the instant invention do not degrade with cycling. This can be seen graphically in FIG. 3 which is an absorption plot of stored hydrogen versus time for an alloy material of the instant invention at 300° C. for cycle 50 (represented by the ▴ symbol) and cycle 650 (represented by the  symbol). As shown in FIG. 3, the alloy materials of the instant invention have virtually identical hydrogen storage capacity and absorption kinetics at cycle 650 as they do at cycle 50 . While the present test was terminated at 650 cycles, all factors indicate that the instant alloys can easily achieve cycle lives of at least 1000 cycles or greater without loss of capacity or kinetics. FIG. 3 is a graph of the Pressure-Composition-Temperature (PCT) curves of alloy FC-10 at 279° C. (represented by the ∘ symbol), 306° C. (represented by the ▴ symbol) and 335° C. (represented by the Δ symbol). The graph shows that the alloy has plateau pressures of 1050 Torr at 279° C., 2200 Torr at 306° C. and 4300 Torr at 335° C. The PCT curve shows that the FC-10 alloy has a maximum capacity of about 6.5 weight % hydrogen, and a hydrogen bond energy of about 70 kJ/mole. FIG. 4 is a graph of the PCT curves of alloy FC-76 at 278° C. (represented by the ▪ symbol), 293° C. (represented by the ♦ symbol) and 320° C. (represented by the ▴ symbol). The graph shows that the alloy has plateau pressures of 750 Torr at 278° C., 1100 Torr at 293° C. and 2400 Torr at 320° C. The PCT curve shows that the FC-76 alloy has a maximum capacity of about 6.9 weight % hydrogen, and a hydrogen bond energy of about 75 kJ/mole. FIG. 5 is a plot of the absorption kinetics of the FC-76 alloy. Specifically, weight % hydrogen absorption versus time is plotted for 3 temperatures 275° C. (⋄ symbol), 300° C. (∘ symbol), and 325° C. (Δ symbol). As can be seen, at 275° C. the alloy absorbs 80% of it's total capacity in 1.3 minutes, at 300° C. the alloy absorbs 80% of it's total capacity in 1.4 minutes, and at 325° C. the alloy absorbs 80% of it's total capacity in 2.0 minutes. FIG. 6 is a plot of the desorption kinetics of the FC-76 alloy. Specifically, weight % hydrogen desorption versus time is plotted for 3 temperatures 275° C. (□ symbol), 300° C. (∘ symbol), and 325° C. (Δ symbol). As can be seen, at 275° C. the alloy desorbs 80% of it's total capacity in 8.0 minutes, at 300° C. the alloy desorbs 80% of it's total capacity in 3.4 minutes, and at 325° C. the alloy debsorbs 80% of it's total capacity in 2.5 minutes. FIG. 7 is a plot of the absorption kinetics of the FC-86 alloy. Specifically, weight % hydrogen absorption versus time is plotted for 3 temperatures 230° C. (⋄ symbol), 240° C. (∘ symbol), and 275° C. ( symbol). As can be seen, at 230° C. the alloy absorbs 80% of it's total capacity in 5.2 minutes, at 300° C. the alloy absorbs 80% of it's total capacity in 2.4 minutes, and at 325° C. the alloy absorbs 80% of it's total capacity in 2.3 minutes. FIG. 8 is a plot of the absorption kinetics of FC-76 alloy powders having two different particle sizes. Specifically, weight % hydrogen absorption versus time is plotted for material having a particle size range of 75-250 microns (∘ symbol), and 32-63 microns (⋄ symbol). As can be seen, the smaller particle size greatly enhances the absorption kinetics. While the method of forming the instant powders in the examples above was rapid solidification and subsequent grinding, gas atomization may also be used. When the materials are ground, use of an attritor is the preferred method of grinding. Particularly useful is the addition of a grinding agent, such as carbon, when grinding these alloys. The present invention includes a metal hydride hydrogen storage means for storing hydrogen within a container or tank. In one embodiment of the present invention, the storage means comprises a the afore described hydrogen storage alloy material physically bonded to a support means. Generally, the support means can take the form of any structure that can hold the storage alloy material. Examples of support means include, but are not limited to, mesh, grid, matte, foil, foam and plate. Each may exist as either a metal or non-metal. The support means may be formed from a variety of materials with the appropriate thermodynamic characteristics that can provide the necessary heat transfer mechanism. These include both metals and non-metals. Preferable metals include those from the group consisting of Ni, Al, Cu, Fe and mixtures or alloys thereof. Examples of support means that can be formed from metals include wire mesh, expanded metal and foamed metal. The hydrogen storage alloy material may be physically bonded to the support means by compaction and/or sintering processes. The alloy material is first converted into a fine powder. The powder is then compacted onto the support means. The compaction process causes the powder to adhere to and become an integral part of the support means. After compaction, the support means that has been impregnated with alloy powder is preheated and then sintered. The preheating process liberates excess moisture and discourages oxidation of the alloy powder. Sintering is carried out in a high temperature, substantially inert atmosphere containing hydrogen. The temperature is sufficiently high to promote particle-to-particle bonding of the alloy material as well as the bonding of the alloy material to the support means. The support means/alloy material can be packaged within the container/tank in many different configurations. FIG. 9 shows a configuration where the support means/alloy material is spirally wound into a coil. FIG. 10 shows an alternate configuration where the support means/alloy material is assembled in the container as a plurality of stacked disks. Other configurations are also possible (e.g. stacked plates). Compacting and sintering alloy material onto a support means increases the packing density of the alloy material, thereby improving the thermodynamic and kinetic characteristics of the hydrogen storage system. The close contact between the support means and the alloy material improves the efficiency of the heat transfer into and out of the hydrogen storage alloy material as hydrogen is absorbed and desorbed. In addition, the uniform distribution of the support means throughout the interior of the container provides for an even temperature and heat distribution throughout the bed of alloy material. This results in a more uniform rates of hydrogen absorption and desorption throughout the entirety thereof, thus creating a more efficient energy storage system. One problem when using just alloy powder (without a support means) in hydrogen storage beds is that of of self-compaction due to particle size reduction. That is, during repeated hydriding and dehydriding cycles, the alloy materials expand and contract as they absorb and desorb hydrogen. Some alloy materials have been found to expand and contract by as much as 25% in volume as a result of hydrogen introduction into and release from the material lattice. As a result of the dimensional change in the alloy materials, they crack, undergo fracturing and break up into finer and finer particles. After repeated cycling, the fine particles self-compact causing inefficient hydrogen transfer as well as high stresses that are directed against the walls of the storage container. However, the processes used to attach the alloy material onto the support means keeps the alloy particles firmly bonded to each other as well as to the support means during the absorption and desorption cycling. Furthermore, the tight packaging of the support means within the container serves as a mechanical support that keeps the alloy particles in place during the expansion, contraction and fracturing of the material. The instant alloys and storage material systems are useful as hydrogen supplies for many applications. One such application is the field of automobiles. Specifically, the systems can be used as a source of hydrogen for internal combustion engine (ICE) vehicles or fuel cell (FC) vehicles. FIG. 11 shows a schematic representation of a hydrogen gas supply system for an ICE vehicle, which is for supplying a hydrogen engine 1 with hydrogen gas. The system has a hydrogen gas storage portion 2 and an engine waste heat transfer supply passage 3 which leads engine waste heat (in the form of exhaust gas or engine coolant) discharged from the engine 1 to the hydrogen gas storage portion 2 . The system also includes a return passage 4 for returning any engine coolant used to heat the hydrogen storage material back to the engine 1 and an exhaust gas vent 7 for releasing used exhaust gas. The system further includes a hydrogen gas supply passage 5 which leads hydrogen gas from the hydrogen gas storage portion 2 to the engine 1 . The engine waste heat transfer supply passage 3 is provided with a temperature regulating portion 6 which regulates the temperature of the waste heat to be introduced into the hydrogen gas storage portion 2 . With such a system, waste heat generated within the ICE can be efficiently used to heat the hydrogen storage material to release hydrogen therefrom for use in the ICE. FIG. 12 shows a schematic representation of a hydrogen gas supply system for an FC vehicle, which is for supplying a fuel cell 8 with hydrogen gas. The system has a hydrogen gas storage portion 12 and a fuel cell waste heat/hydrogen transfer supply passage 9 which leads fuel cell waste heat and unused hydrogen discharged from the fuel cell 8 to a hydrogen gas combustor 10 . Waste heat from the fuel cell may be in the form of heated gases or heated aqueous electrolyte. The hydrogen combustor 10 , heats a thermal transfer medium (preferably in the form of the aqueous electrolyte from the fuel cell) utilizing waste heat from the fuel cell 8 , and by combusting hydrogen. Hydrogen is supplied to the combustor 10 via unused hydrogen from the fuel cell 8 , and via fresh hydrogen supplied from the hydrogen storage unit 12 via hydrogen supply line 14 . Heated thermal transfer medium is supplied to the hydrogen storage unit 12 via supply line 13 . The system also includes a return passage 16 for returning any fuel cell aqueous electrolyte used to heat the hydrogen storage material back to the fuel cell 8 and an exhaust gas vent 15 for releasing used combustor gas. The system further includes a hydrogen gas supply passage 11 which leads hydrogen gas from the hydrogen gas storage unit 12 to the fuel cell 8 . While the invention has been described in connection with preferred embodiments and procedures, it is to be understood that it is not intended to limit the invention to the described embodiments and procedures. On the contrary it is intended to cover all alternatives, modifications and equivalence which may be included within the spirit and scope of the invention as defined by the claims appended hereinafter.

4y

[0001] This invention relates to an angular motion control system and method. More particularly, but not by way of limitation, this invention relates to precise and small angular motion control by the mechanical motion translation from linear to rotary motion program. SUMMARY OF THE INVENTION [0002] An apparatus for imparting an angularly rotational movement is disclosed. The apparatus comprises a cylinder having an internal portion, a rod operatively positioned within the internal portion of the cylinder, a first unidirectional bearing operatively positioned about the rod, and a second unidirectional bearing operatively positioned about the rod. The apparatus may also include means for selectively inputting incremental radial motion to the rod. In one embodiment, the apparatus further includes means for linearly moving the cylinder in a linear axial motion so that the rod is moved linearly along an axis of the cylinder. Additionally, the selective inputting means includes a groove operatively placed within the rod and a protuberance formed on the second unidirectional bearing. Also, the first bearing may contain a spline member on an outer diameter surface, and wherein the spline member is operatively attached to an inner diameter surface of the cylinder and wherein an inner diameter surface of the first bearing is attached to an outer diameter surface of the rod. [0003] In one embodiment of the apparatus, an outer diameter surface of the second bearing is attached to the inner diameter of the cylinder and wherein the second bearing contains a spline member on an inner diameter surface, and wherein the spline member is operatively attached to the outer diameter surface of the rod. The inner diameter surface of the first bearing may be attached to the outer diameter surface of the rod by welding and the outer diameter surface of the second bearing may be attached to the inner diameter surface of the cylinder by welding. In one preferred embodiment, the first and second bearing rotates in a clockwise direction. [0004] A system for imparting an angularly rotational movement is also disclosed. The system comprises: a cylinder having an internal portion; a rod operatively positioned within the internal portion of the cylinder; a first bearing operatively positioned about the rod; a second bearing operatively positioned about the rod; a motion assembly for turning the rod in preselected radial increments. The system may also include a linear force generator, operatively attached to the rod, so that the cylinder is moved linearly along an axis of the cylinder. [0005] In one embodiment of the system, the motion assembly includes a groove operatively placed within the rod and a protuberance formed on the second unidirectional bearing. The first bearing may contain a spline member on an outer diameter surface, and wherein the spline member is operatively attached to an inner diameter surface of the cylinder; and wherein an inner diameter surface of the first bearing is attached to an outer diameter surface of the rod. In one preferred embodiment, an outer diameter surface of the second bearing is attached to the inner diameter of the cylinder and the second bearing contains a spline member on an inner diameter surface, and wherein the spline member is operatively attached to the outer diameter surface of the rod. Also, the first and second bearings are unidirectional so that rotation is allowed in only a single direction about a center axis of the rod. [0006] A method for importing an incremental radial movement is also disclosed. The method includes providing a system containing a cylinder having an internal portion; a rod operatively positioned within the internal portion of said cylinder; a first bearing operatively positioned about the rod; a second bearing operatively positioned about the rod; a groove operatively placed within the rod and a protuberance formed on the second unidirectional bearing; wherein the first bearing contains a spline member on an outer diameter surface, and wherein the spline member is operatively attached to an inner diameter surface of the cylinder; and wherein an inner diameter surface of the first bearing is attached to an outer diameter surface of the rod; the inner diameter surface of the cylinder is attached to the outer diameter of the rod. The method further includes engaging the protuberance formed on the second unidirectional bearing with the groove on the rod, creating a linear force in a first direction on the cylinder along the cylinder's center of axis, transferring the linear force from the protuberance to the rod, slidably displacing the rod a predetermined distance, and angularly rotating the rod a predetermined radial distance. The method may further include creating a linear force in a second direction on the rod along the cylinder's center of axis, wherein the second direction of the linear force is opposite the first direction of the linear force. BRIEF DESCRIPTION OF THE DRAWINGS [0007] FIG. 1 is a schematic illustration of one embodiment of the apparatus of the present invention. [0008] FIG. 2 is a partial sectional view of the apparatus illustrated in FIG. 1 . [0009] FIG. 3 is an enlarged view of the area “3” seen in FIG. 2 . [0010] FIG. 4A is a cross-sectional view of one of the disclosed embodiments of the apparatus taken along line 4 - 4 of FIG. 1 . [0011] FIG. 4B is a cross-sectional view of a second embodiment of one of the disclosed embodiments of the apparatus taken along line 4 - 4 of FIG. 1 . [0012] FIG. 4C is a cross-sectional view of a third embodiment of one of the disclosed embodiments of the apparatus taken along line 4 - 4 of FIG. 1 . [0013] FIG. 4D is a cross-sectional view of a fourth embodiment of one of the disclosed embodiments of the apparatus taken along line 4 - 4 of FIG. 1 . [0014] FIG. 5 is the schematic illustration of the apparatus seen in FIG. 1 with the angle of rotation theta shown. [0015] FIG. 6A is a graph of the displacement and the angle of rotation theta. [0016] FIG. 6B is a graph of the angle of rotation and the time cycle of the system herein disclosed. [0017] FIG. 6C is a graph of the displacement of the rod and one complete cycle of time for the system herein disclosed. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS [0018] Referring now to FIG. 1 , a schematic illustration of one embodiment of the apparatus 2 of the present disclosure will now be described. The apparatus 2 includes a cylinder 4 that has a rod 6 partially disposed therein. The cylinder 4 may be referred to as a motion translator 4 . As noted in FIG. 1 , the output 8 is shown (one-way), wherein the output is the angular rotation around the rod 6 and the input 10 (bi-directional) is the reciprocating linear motion along the axis 12 as will be described later in the description. A force generator 13 (such as a hydraulic piston) may be connected to the rod 6 for providing a bi-directional linear force input to the system. [0019] FIG. 2 is a partial sectional view of some of the components of the apparatus 2 illustrated in FIG. 1 . FIG. 2 depicts the rod 6 concentrically disposed within unidirectional bearings therein. It should be noted that like numbers refer to like components in the various drawings. The sectional view of FIG. 2 depicts the internal bearing 14 and the internal bearing 16 , wherein the bearings 14 , 16 are unidirectional so that the bearings 14 , 16 only rotate in a single direction, which is in the clockwise direction of the output arrows 8 . The bearings 14 and 16 are commercially available from Ringspann under the name Internal Freewheels ZZ. [0020] Referring now to FIG. 3 , an enlarged view of the area “3” seen in FIG. 2 will now be described. FIG. 3 depicts the bearing RB 16 along with the unidirectional arrow 18 which depicts the clockwise rotation of the bearing 16 . The bearing 16 is concentrically disposed within the cylinder 4 (not seen in this view), and the rod 6 is concentrically disposed within the bearing RB 16 , as previously disclosed. FIG. 3 also depicts the path 20 , wherein the path 20 is a groove on the surface of the rod 6 . The path 20 , in one embodiment, is a predetermined curved groove as will be further explained later in the description. The bearing 16 will have a protuberance 22 , sometimes referred to as a notch, formed thereon, and the protuberance 22 will engage the path 20 so that an input 10 , which consist of a linear motion, will create an output 8 that is an angular motion, as will be more fully described later in the description. [0021] The rotational angular movement per cycle is determined by the motion program seen generally in FIGS. 2 and 3 . The motion program includes the bearing 14 , the bearing 16 , the rod 6 , the cylinder 4 , the path 20 and the protuberance 22 . As noted earlier, the unidirectional bearings 14 , 16 are placed such that both bearings 14 , 16 provide the same unidirectional rotation to the rod 6 . [0022] FIG. 4A is a cross-sectional view of the apparatus 2 taken along line 4 - 4 of FIG. 1 . The bearing 14 is shown along with the bearing 16 disposed within an inner portion of the cylinder 4 . The bearing 14 will be attached to the rod 6 with means for attachment 24 , wherein the attachment means may be by welding the inner portion of the bearing 14 to the outer portion of the rod 6 . Also, the outer portion of the bearing 14 will be slidably attached to the inner portion of the cylinder 4 with slidably attachment means 26 a , 26 b , wherein the slidably attachment means 26 a and 26 b may be a spline member or a tongue-in-groove member, for instance. [0023] With respect to the bearing 16 , the bearing 16 will be attached to the cylinder 4 with means for attachment 28 , wherein the attachment means may be by welding the inner portion of the cylinder 4 to the outer portion of the bearing 16 . Also, the inner portion of the bearing 16 will be slidably attached to the outer portion of the rod 6 with slidably attachment means 30 a and 30 b , wherein the slidably attachment means 30 a , 30 b may be, for instance, a spline member or a tongue-in-groove member. The slidably attachment means 30 a , 30 b allows for straight and parallel displacement along the rod and cylinder axis 12 . [0024] As noted earlier, the bearing 14 and 16 are unidirectional. FIG. 4A also depicts the direction of bearing rotation, wherein the “dot” within the circle 32 represents the bearing rotation in the direction of coming out of the drawing and the “X” in the circle 34 represents the bearing rotation in the direction going into the drawing. [0025] FIG. 4A also shows the paths, seen generally at 36 a and 36 b , wherein the pair of paths 36 a , 36 b are placed onto the outer surface of the rod 6 at approximately 180° phase to each other. The paths 36 a , 36 b may also be referred to as grooves 36 a and 36 b . It should be noted that the apparatus 2 is operable with a single path, such as path 36 a only. The radius “r” of the rod 6 is also seen in FIG. 4A . As per the teachings of this disclosure, the path 36 a , 36 b contain predetermined curves, wherein the paths 36 a , 36 b will enable incremental angular movement according to the motion program (which is also referred to as the motion assembly). Additionally, FIG. 4A depicts the cross-sectional view of the bearings 14 , 16 . For instance, bearing 14 has an inner cylindrical member 37 a , an outer cylindrical member 37 b , ball bearings 37 c in between, and means for allowing only unidirectional bearing rotation, as well understood by those of ordinary skill in the art. [0026] FIG. 4B is a cross-sectional view of a second embodiment of one of the disclosed embodiments of the apparatus 2 taken along line 4 - 4 of FIG. 1 . With the embodiment of FIG. 4B , the bearings 14 , 16 are welded to the inner portion of the cylinder 4 . The rod 6 is slidably attached to the inner portion of the bearing 14 with slide mechanisms SM1, SM2 for linear movement. The rod 6 is slidably attached to the inner portion of the bearing 16 for movement in accordance with the motion program, which is also referred to as the motion assembly, which includes the paths P1, P2. It should be noted that redundancies of similar components previously discussed, such as the bearings, attachment means, the slide mechanism grooves and notches will not be repeated in detail with the description of FIGS. 4B , 4 C and 4 D. [0027] FIG. 4C is a cross-sectional view of a third embodiment of one of the disclosed embodiments of the apparatus 2 taken along line 4 - 4 of FIG. 1 . With this embodiment, the bearing 14 is attached (i.e. welded) to the inner portion of the cylinder 4 and the inner portion of the bearing 14 is slidably attached with a slide mechanism SM1, SM2 to the rod 6 for linear movement. The inner portion of the bearing 16 is welded to the rod 6 and the outer portion of the bearing 16 is slidably attached to the inner part of the cylinder 4 with the motion assembly i.e. the paths P1, P2 are on the inner portion of the cylinder, and male notches are on the outer portion of bearing 16 as previously described. [0028] Referring now to FIG. 4D , a cross-sectional view of a fourth embodiment of the present disclosure will now be described. With this embodiment, the bearing 14 is welded to the rod 6 and the bearing 14 is slidably attached to the inner portion of the cylinder 4 for linear movement. The bearing 16 is welded to the rod 6 and the bearing 16 is slidably attached to the inner portion of the cylinder 4 , wherein the outer portion of the bearing 16 is slidably attached for movement in accordance with the motion assembly i.e. the paths P1, P2 are on the inner portion of the cylinder, and male notches are on the outer portion of bearing 16 as previously described. [0029] Referring now to FIG. 5 , a schematic illustration of the apparatus 2 seen in FIG. 1 with the angle of rotation will now be described. More specifically, the rod 6 is disposed within the cylinder 4 . The radius “r” of the rod 6 is shown, and the angle theta 40 is shown, wherein in one embodiment the angle theta 40 is between slightly above zero (0) degrees to about ten (10) degrees. FIG. 5 also shows the displacement “d” of the rod 6 , wherein the displacement “d” represents the amount of linear movement of the rod 6 in a half-cycle. [0030] FIG. 6A is a graph of the displacement “d” and the angle of rotation theta. Hence, theta 1 is the angle of rotation during a first half cycle. An entire cycle consist of the angle rising to theta 1 (until the first half cycle for theta 1 is reached) then the displacement again reverts back to zero (for the second half cycle). FIG. 6A then shows that the angle incrementally increases to theta 2 for the start of another cycle, wherein the theta 2 corresponds to the displacement d. [0031] Referring now to FIG. 6B , a graph of the theta angle of rotation and the time cycle of the system is illustrated. More specifically, the time t ½ represents a half cycle and t1 represents a full cycle. Hence, the angle of rotation increases during the first half cycle to theta 1, while the angle theta 1 remains constant (i.e. unchanged) during the second half cycle. [0032] FIG. 6C is a graph of the displacement “d” of the rod 6 for one complete cycle of time for the system herein disclosed. Therefore, the displacement “d” rises during the first half cycle to “d”, and during the second half cycle, the displacement “d” decreases back to zero by the end of a complete cycle. [0033] With collective reference to FIGS. 1-6 , the operation of the apparatus 2 will now be described. The movement of the rod 6 from left to right on the linear axial movement is called “forward” movement for the purpose of this description. This forward movement includes the displacement from the far most right to the far most left on FIG. 2 . Therefore, “backward” displacement will be the exact opposite of the movement from the far most left to the far most right of the rod 6 . [0034] With reference to the forward movement, as the rod 6 linearly moves through the first unidirectional bearing 16 , the male notch 22 on the bearing 16 will move within the path 20 . Since the bearings 14 and 16 are unidirectional, when the path asserts the force on the notch 22 , the component of the force that will try to move the bearings 14 , 16 opposite to the uni-direction will be met with the resisting force from the bearing 14 , 16 to the path 20 . The remaining component of the force that is parallel to the cylinder 4 displacement the bearing will assert back the reaction forces and cancelled. Thus the resulting force will act on the cylinder 4 as a torque to turn the cylinder 4 . The component of the force that follows in the direction of bearing rotation, the force will spent on turning the bearings 14 , 16 . For the case of the FIG. 3 , the component of the force will torque the cylinder 4 to turn in the direction shown by the arrow in the diagram. The rotational direction show by the diagram is “clockwise” for the convention of this document. [0035] Referring specifically to the embodiment of FIG. 4A , the clockwise motion will be explained Note that the bearing 16 is welded to the inner portion of the cylinder 4 at the outer portion of the bearing 16 whereas the bearing 14 is welded to the rod 6 at the inner bearing 14 . In addition, the outer portion of the bearing 14 is designed to be able to slide along an inner portion of the cylinder 4 in conjunction with the linear displacement of the rod 6 but no angular motion of the bearing 14 with respect to the cylinder 4 is allowed. [0036] Therefore, the clockwise motion of the rod 6 will turn the inside bearing of bearing 14 and the whole bearing 14 will slide linearly along with the rod 6 . [0037] When the rod 6 reaches the most left position, the angular motion of the rod 6 also stops. This is the end of a half cycle. The other half occurs during the backward movement. [0038] With reference to the backward movement, as the rod 6 moves back from the most left position of the displacement, the path 20 on the rod 6 asserts a force (action) on the bearing 16 to turn clockwise. This is in the direction of the rotation for the bearing 16 ; the bearing 16 will turn but not the rod 6 . The turning of the bearing 16 , in the entire system, presents the least amount of force required in the return process. The rod 6 is tightly held by the bearing 14 system in place so that the rod 6 itself will not turn counterclockwise. This second bearing ensures that it is the bearing 14 turning clockwise even though there is force on the rod 6 to turn counterclockwise (reaction). The bearing 14 ensures that during the last half cycle, the rod 6 will maintain the same position in the angular position. [0039] In the design of systems, designers find it necessary to control angular motion of members including tubular members. An application of the present disclosure includes a rod rotator that is installed inside a hydraulic pump that turns the rod string continuously in one direction while traveling up and down the well bore to reduce the wearing. [0040] An aspect of one embodiment of the present disclosure is the apparatus and method translates a linear and reciprocating motion in the axial direction of the cylinder 4 into a unique unidirectional angular rotational motion of the same cylinder 4 around an axis 10 , as seen in FIG. 1 . The linear motion is reciprocating along a set distance. Another aspect of one embodiment is that each reciprocating motion completes with the design upper limits and lower limits of the distance that the cylinder travels in the axial direction. The angular rotation is around the axis 10 of the rod 6 . In one preferred embodiment, the angular rotation is limited to between 1 degree and 10 degrees per cycle of linear motion. Yet another aspect of the present embodiments is the simplicity of the mechanical translation. [0041] Yet another aspect of the disclosure is that the detailed motion program in the first cycle of theta is completely controlled by the path program designed on the surface of the rod 6 . This is controlled by the machining quality of the time and mathematical definitions of relationships between theta and the displacement “d”. [0042] Although the present invention has been described in considerable detail with reference to certain preferred versions thereof, other versions are possible. Therefore, the spirit and scope of the appended claims should not be limited to the description of the preferred versions contained herein.

4y

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates generally to a gas switch, and more particularly to a gas switch that is capable of achieving smooth adjustment of fire in different intensity from strong fire to weak fire. 2. Description of the Related Art Conventionally, the method used in a gas switch to adjust fire intensity is often achieved by using a drive rotating shaft to drive a fastener inside the switch body to rotate, so as to make air ports or guide slots in different diameter on the fastener correspond with air intake holes inside the switch body respectively. In such a way, the gas switch will generate different fire intensity as the drive rotating shaft revolves to release gas of different flows. Since usually there is space between the air ports or guide slots in different diameter, the cross section area for gas flows will not be evenly altered in the process of adjusting different air ports or guide slots to correspond with the air intake. As a result, it is impossible to achieve smooth and linear changes in the course of adjusting fire among different intensities, thus further making it impossible for users to finely adjust the fire intensity of gas stoves effectively. To solve this problem, someone designed a kind of gas switches able to adjust fire intensity. On the fastener of such gas switch, only one guide slot and gas guide hole is installed and connected with the internal through hole, and the guide slot is joint with the gas intake hole. So, the slide guide component built on the drive shaft rod can work with the undulant guide to make the drive rotating shaft generate axial displacement as the shaft rotates, thus changing the space between one end of the fastener rod and the air outlet hole and further adjusting the cross-section area for gas flows. By doing so, it will achieve relatively smooth changes among fires of high, medium and low intensities. While the aforesaid design of gas switches can lead to smooth changes of fire in different intensity, its slide guide component in the shape of a round rod can be built into the slot at one end of the fastener, in addition to working with the guide. Therefore, the drive rotating shaft can drive the fastener to rotate as it revolves. In another word, the slide guide component serves not only as a structure to control axial displacement of the drive shaft rod, but also as a component to rotate the fastener. However, the slide guide component is liable to wear and tear due to friction with walls of the fastener slot in the long period and effect of payloads generated in driving the fastener to rotate since it is a tiny component in the shape of a round rod. Moreover, in the cases where the slide guide component is worn out, control error will occur in the process of working with the guide to make the drive shaft rod generate axial displacement, which, in return, will lead to the result that fires in different intensities cannot be smoothly changed in a real way. Therefore, it is obvious that such gas switches still have defects in practical applications. SUMMARY OF THE INVENTION The primary objective of the present invention is to provide a gas switch capable of adjusting fire intensity finely, which can eliminate the above-mentioned shortcoming that slide guide components of gas switches are subject to wear and tear, and can really achieve smooth and linear changes of fires in different intensity, thus achieving better effect of fine adjustment of fire intensity. According to the objective of the present invention, the present invention provides a gas switch capable of adjusting fire intensity finely, comprising a switch body which includes a base and a cover. In the base, there is a conical valve chamber with an opening at one end and a gas intake hole as well as a gas outlet hole connected through the valve chamber, while the cover is placed at the side opposite to the valve chamber of the base, and a guide is installed inside the cover; a valve set, which is installed and rotates inside the valve chamber and includes a hollow valve and a pilot valve. On the valve, there are several air ports and inside it, there is a control port. The pilot valve can move elastically inside the valve with one control structure installed at one end of it, which always closes the control port when the pilot valve is not pushed; a drive component installed on the cover, which contains a rotating rod that rotates round and moves along the same shaft of the valve set; a guide rod installed on the rotating rod and leans on the guide; a regulating block which can move along the rotating rod and is closely connected with the pilot valve; and a connecting component for linking the drive component with the valve set flexibly. BRIEF DESCRIPTION OF THE DRAWINGS In the following paragraphs, an example of the preferred embodiment of the present invention is given with reference to the accompanying drawings to further describe the present invention in detail as follows, wherein: FIG. 1 is a schematic view of a first preferred embodiment of the present invention; FIG. 2 is a perspective view of the cover and drive component of the first preferred embodiment of the present invention; FIG. 3 is a sectional view along the 3 - 3 line of FIG. 2 ; FIG. 4 shows schematically an act according to one example of the preferred embodiments of the present invention, which indicates the state in which the drive component rotates by 90 degrees; FIG. 5 is a gas flow curve diagram of the first preferred embodiment of the present invention; FIGS. 6A-6D show a schematic view of the first preferred embodiment of the present invention, illustrating changes in the relationship between the guide rod and the guide following rotation of the drive component; and FIG. 7 is a schematic view of a second preferred embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION Refer to FIGS. 1 to 3 , which show that the gas switch 10 comprises a switch body 12 , a valve set 14 , a drive component 16 and a connecting component 18 according to one example of the preferred embodiment of the present invention. The switch body 12 consists of a base 22 and a cover 24 . Inside the base 22 , there is a conical valve chamber 26 with an opening at one end and a gas intake channel 28 and a gas outlet channel 30 , both of which are connected through the conical valve chamber 26 , while the cover 24 is placed at one side of the base 22 , and at the side opposite to valve chamber 26 , there is a containing hole 31 and a guide 32 . And there is an inclining section 34 , a first flat section 36 , a declining section 38 and a second flat section 40 that reaches out around the containing hole 31 . The inclining section 34 gradually approaches the valve set 14 in a inclined way, while the declining section 38 moves gradually faraway from the valve set 14 in a inclined way. The valve set 14 can be installed rotatably inside the valve chamber 26 and includes a valve 42 , a pilot valve 44 , a leakage stopping component 46 and a spring 48 . And the valve 42 has a conical switch body 50 and a protrusive ring 52 that projects above one end of the switch body 50 , and there is a joint structure 53 between the switch body 50 and the protrusive ring 52 . On the axis of the switch body 50 , there is a through channel 54 divided into one part of big diameter 56 and the other part of small diameter 58 , and a control port 60 is formed in the place where the part of big diameter 56 and the other part of small diameter 58 are connected. Besides, on the surface of the switch body 50 , a guide slot 62 is installed to connect the gas intake channel 28 and a gas intake hole 64 is set to connect the guide slot 62 with the part of small diameter 58 . The pilot valve 44 passes through the channel 54 of the switch body 50 , and includes a rod section 66 and a pushing control section 68 which is placed at one end of the rod section 66 to correspond with the control port 60 . The leakage stopping component 46 is equipped with an O-shaped ring and a circular gasket placed inside the joint structure 53 on the outward side of the rod section 66 . The spring 48 is fixed by a clamping component 74 at the external side of the rod section 66 and leans against the gasket, so that the control section 68 can seal the control port 60 when no pushing force is applied to the pilot valve 44 . The drive component 16 is installed on the cover 24 and comprises a rotating rod 76 , a guide rod 78 and a regulating block 80 , and can rotate and move through the containing hole 31 of the cover 24 to reach into the interior of the protrusive ring 52 of the valve 42 . On the rotating rod 76 , there is an axle hole 82 combined with one end of the pilot valve 44 to form an internal thread 84 , so as to allow the regulating block 80 to be movably installed inside and lean against the pilot valve 44 . The guide rod 78 is a round rod fixed on the rotating rod 76 and close to the surface of the guide 32 , so as to make it move on the surface of the guide 32 when the rotating rod 76 begins to revolve, thus causing the rotating rod 76 to generate axial displacement due to undulations on the surface of the guide 32 . The regulating block 80 is a bolt, and there is a connecting component 86 at one end of the bolt close to the pilot valve 44 . The connecting component 86 presents a roughly conical cross section in order to be connected with the valve 44 with low friction. The connecting component 18 consists of two circular contact plates 88 and 89 and a spring 90 . The two contact plates 88 and 89 surround the rotating rod 76 and the protrusive ring 52 of the valve 42 , while the spring 90 is linked with the two contact plates 88 and 89 at the external side of the rotating rod 76 and protrusive ring 52 , so that the valve set 14 can be rotated by the rotating rod 76 as it revolves. In addition, the gas switch 10 also includes a digital ignition 19 commonly seen in ordinary gas switches, which is installed on the cover 24 . The gas switch 10 of the present invention has the features as follows: When the drive component 16 is rotated, the guide rod 78 will move along the surface of the guide 32 , which will further cause the rotating rod 78 to generate axial displacement as there are undulations on the surface of the guide 32 . This will press the pilot valve 44 and change the space between the control section 68 and the control port 60 , thus altering the fire intensity smoothly. To put it in detail, as shown in FIG. 4 and the A line of FIG. 5 , when the gas switch 10 performs ignition actions (generally rotate the rotating shaft by 90 degrees), the drive component 16 will be rotated, pressing the guide rod 78 to move to the first flat section 36 along the inclining section 34 . So the drive component 16 will move towards and push the pilot valve 44 , causing the control section 68 not to seal the control port 60 any more. As a result, gas will be discharged through the guide slot 62 and gas intake hole 64 into the part of small diameter 58 , and further released out of the gas outlet channel 30 through the part of big diameter 56 for burning, as shown in FIG. 4 . At this moment, the space between the control section 68 and the control port 60 reaches its maximum, hence the gas flows will reach its maximum and the fire intensity will be the highest, as shown in FIGS. 6A and 6B . Yet as the drive component 16 continues to be rotated by more than 90 degrees, the guide rod 78 will pass over the first flat section 36 and slide into the declining section 38 , as shown in FIG. 6C . In such cases, the drive component 16 will gradually move outwards due to effect of tensile force of the spring 90 in the connecting component 18 , causing the pilot valve 44 to move outwards, too, due to effect of tensile force of the spring 48 . This will lead to reduced space between the control section 68 and the control port 60 , as a result, the gas flows will gradually reduce and the fire intensity will grow weaker. When the drive component 16 is rotated by 270 degrees, the guide rod 78 will slide onto the second flat section 40 at the end of the declining section 38 , and the fire intensity will be kept at the lowest level, as shown in FIG. 6D . Secondly, when the gas switch 10 is kept in the position of ultimate fire intensity (lowest fire intensity), the fire intensity cannot be changed or adjusted finely, because the space between the control section 68 and the control port 60 will not change any more. At this point, tools may be used to rotate the regulating block 80 so as to make it protrude or retract slightly, and then the pilot valve 44 will move backwards or forwards slightly due to effect of the pushing force from the regulating block 80 . In this way, the space between the control section 68 and the control port 60 can be enlarged or shortened slightly to increase or reduce gas flows, thus making the fire intensity become stronger or weaker and eventually achieving fine adjustment of fire intensity, as shown in the B and C lines in FIG. 6 . As shown in FIG. 7 , it may also be decided in the present invention that the cross section of the connecting component 86 of the regulating block 80 is roughly like a curve, in order to keep it also in the state of low-friction contact with the pilot valve 44 . This will prevent the cases where the regulating block 80 drives the pilot valve 44 to rotate as the drive component 16 rotates the valve set 14 and ensure that the structure works normally. It can be seen from the above descriptions that the gas switch described in the present invention relies on the synergy of the guide rod and the guide to make the drive component and the pilot valve move axially and very smoothly, and further cause linear changes in the process of adjusting firepower in different intensity, thus achieving good results in fine adjustment of fire intensity. Besides, the valve set is rotated because of the effect of the driving force from the drive component, not because of that from the guide rod; therefore the guide rod is not liable to wear and tear, thus securing smooth and linear change in the process of fire intensity adjustment. Moreover, the regulating block can achieve the effect of adjusting the final fire intensity of the gas switch.

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CROSS-REFERENCE TO RELATED APPLICATION [0001] This application claims priority from provisional application Serial No. 60/333,943 filed Nov. 28, 2001. FIELD OF THE INVENTION [0002] The present invention relates to the conversion of chemical energy to electrical energy. More particularly, the present invention relates to a current collector useful in electrochemical cells of both aqueous and non-aqueous chemistries. BACKGROUND OF THE INVENTION [0003] Present electrochemical cell designs primarily utilize two construction methods. Either the internal electrodes are spirally wound or they are assembled in a multiple plate or multiplate configuration. In either case, each of the positive and negative electrodes is comprised of a current collector and active chemical constituents contacted thereto. The current collector can either be the casing housing the cell or a conductive substrate, such as a foil or screen. [0004] The current collector of the present invention comprises a substrate having a unique pattern of openings that facilitate improved discharge. The openings are larger adjacent to the current collector tab, becoming smaller as the distance from the tab increases. The present current collector is useful in both spirally wound and multiplate cell types for both primary and secondary chemistries. SUMMARY OF THE INVENTION [0005] Accordingly, the present invention is directed to a novel current collector design in which the open areas of the grid pattern converge at an imaginary focal point on a connector tab of the substrate. The openings are grouped into distinct regions with the larger openings immediately adjacent to the connector tab and the smaller openings distant there from. This provides more conductive pathways at greater distances from the tab so that electrode active material contacting the current collector at the smaller openings is more efficiently discharged. [0006] These and other aspects of the present invention will become increasingly more apparent to those skilled in the art by reference to the following description and the appended drawings. BRIEF DESCRIPTION OF THE DRAWINGS [0007] [0007]FIG. 1 is a plan view of one embodiment of a current collector 10 according to the present invention. [0008] [0008]FIG. 1A is a plan view of another embodiment of a current collector 10 A according to the present invention. [0009] [0009]FIG. 1B is a plan view of another embodiment of a current collector 10 B according to the present invention. [0010] [0010]FIG. 2 is a plan view of another embodiment of a current collector 12 according to the present invention. [0011] [0011]FIG. 3 is a plan view of a double winged current collector 14 according to the present invention. [0012] [0012]FIG. 4 is a side elevational view of the current collector 10 of FIG. 1 incorporated into an electrochemical cell 100 . DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS [0013] Referring now to the drawings, FIGS. 1, 1A, 1 B and 2 are views of various embodiments of “single wing” current collectors 10 , 10 A, 10 B and 12 , respectively, according to the present invention while FIG. 3 shows another embodiment of a current collector 12 having a double wing configuration. FIG. 4 is of an exemplary electrochemical cell 100 of a multi-plate configuration comprising one of the present current collectors. Whether the current collector of the cell 100 is of one of the single wing configurations 10 , 10 A, 10 B and 12 or of the double wing type 14 is not necessarily important. [0014] As shown in the enlarged view of FIG. 1, the current collector 10 is a relatively thin substrate comprised of wire or bar-shaped conductor strands in the shape of a frame 14 surrounding a grid 18 and supporting a tab 20 . The conductors and tab are of a conductive material such as nickel, aluminum, copper, stainless steel, tantalum, cobalt and titanium, and alloys thereof. The frame 16 has spaced apart upper and lower strands 22 and 24 extending to and meeting with left and right strands 26 and 28 . Upper frame strand 22 meets left frame strand 26 at curved corner 30 , left frame strand 26 meets lower frame strand 24 at curved corner 32 , lower frame strand 24 meets right frame strand 28 at curved corner 34 , and right frame strand 28 meets upper frame strand 22 at curved corner 36 . [0015] Tab 20 is a generally solid planar member and extends outwardly from the upper frame strand 22 spaced substantially equidistant from the left and right frame strands 26 , 28 . Tab 20 includes left and right sides 38 and 40 extending to and meeting with an intermediate edge 40 . The tab sides 38 and 40 are parallel to each other and generally parallel to the left and right frame strands 26 , 28 . The tab sides 38 and 40 meet the upper frame strand at curved corners 44 and 46 , respectively. If desired, however, the tab 20 can be spaced closer to either of the left or the right frame strand than the other. [0016] The grid 18 is interior of and supported by the frame 16 and generally comprises a first region of openings 48 , a second region of openings 50 and a third region of openings 52 . Openings 48 are larger than openings 50 , which, in turn, are larger than openings 48 . A first transition zone (shown as dashed line 54 ) delineates the extent of the first openings 48 . The area between the first transition zone 54 and a second transition zone (shown as dashed lines 56 ) delineates the area of the second openings 50 . The region between the second transition zone 56 and a distal portion of the left and right frame strands 26 and 28 adjacent to the lower frame strand 24 delineates the area of the third openings 52 . [0017] As more particularly shown in FIG. 1, the first openings 48 are of a rectangular shape oriented with an apex pointed at each of the left and right frame strands 26 , 28 and the upper and lower frame strands 22 , 24 . The first openings 48 propagate or extend from an imaginary focal point 58 on the tab 20 and are uniformly spaced throughout the area bordered by the upper frame strand 22 and the first transition zone 54 . Triangular shaped openings 60 are provided at spaced intervals between the first openings 48 and the upper frame strand 22 . [0018] The second openings 50 are of a rectangular shape positioned in a similar orientation as the first openings 48 . As with the first openings, the second openings are uniformly spaced throughout the region bordered by the first transition zone intersecting the upper frame strand 22 and the second-transition zone 56 intersecting the left and right frame strands 26 , 28 . Triangular shaped openings 62 are provided at spaced intervals between the second openings 50 and the frame strands 22 , 26 and 28 . [0019] The third openings 52 are also of a rectangular shape positioned in a similar orientation as the first and second openings 48 , 50 . The third openings are uniformly spaced throughout the region bordered by the second transition zone 56 and its intersection with the left and right frame strands 26 , 28 and the lower frame strand 24 . As before, triangular shaped openings are provided at spaced intervals between the second rectangular openings 52 and the lower, left and right frame shaped strands 24 , 26 and 28 . [0020] An important aspect of the present invention is the relationship between the regional extent of the first, large openings 48 to the intermediate sized second openings 50 to that of the smaller, third openings 52 . If the distance from the focal point 58 to the first transition zone 54 is “x” , then the distance from the first transition zone to the second transition zone 56 ranges from about 0.2x to about 10x. Also, the distance from the second transition zone 56 to the terminus of the third openings 52 ranges from about 0.2x to about 10x. [0021] An important application of the present invention is use of the current collector 10 in a cathode electrode. During electrochemical cell discharge, electrons from the anode electrode travel through the load and are distributed to the cathode electrode to react with anode ions that have traveled directly through the separator to a reaction site on the cathode active material. It is important that these reactions occur uniformly throughout the cathode electrode, especially when the cathode active material has a higher resistivity than the current collector, such as silver vanadium oxide in a lithium cell (Li/SVO). Although current flow across the current collector is important, current flow across the cathode active material itself is critical because it has a greater impact on the even and uniform discharge of the anode and cathode electrodes. In other words, the transport of electrons to the cathode active material through the cathode current collector must be uniform for a cell to discharge at a constant rate, especially as end-of-life (EOL) discharge approaches. This is particularly the case when the current collector is provided with openings. [0022] In a prior art current collector having openings of a fairly consistent size throughout, it is often seen that the anode material directly opposite or facing that portion of the cathode electrode proximate the tab reacts first. As discharge continues in a conventional cell design, anode material facing those portions of the cathode active material further and further from the cathode tab are reacted. Finally, anode material at the very outer reaches of the anode electrode and facing cathode active material most remote from the cathode tab is reacted. This results in non-uniform discharge, especially as EOL approaches when the cell is subjected to pulse discharge conditions in the Ampere range. An example is when the cell is used to power a cardiac defibrillator during device activation and the discharge is on the order of about 1 to about 4 amps. Non-uniform discharge is not so pronounced when the defibrillator is in a monitoring mode and current is on the order of about 1 microampere to about 100 microampere. [0023] The unique structural configuration of the openings 48 , 50 and 52 of the present current collector 10 prevents such non-uniform discharge. In those areas immediately proximate the current collector tab 20 , where the prior art current collector first experiences the majority of its discharge reactions, the distance from the edge of the current collector pathways bordering an opening to the cathode active material at the opening's center is greater, for example opening 48 , than in an opening of a smaller size, for example openings 50 and 62 . Therefore, while the cathode active material contacting a conductive portion of the current collector and immediately adjacent thereto is readily reacted, the cathode active material further removed from the conductive current collector portions or pathways and closer to the center of any one opening is not so readily reacted. In the present invention, this means the greater distance the electron must travel to react with the cathode active material at the center of a larger opening 48 acts to counterbalance the rapid discharge of the cathode active material proximate the tab. [0024] Accordingly, an electron reacting at a cathode active material site proximate the center of one of the relatively smaller openings 50 and 52 does not travel as far from the conductive pathways as in one of the larger openings 48 . In this manner, the present current collector 10 promotes even and complete discharge of the cathode active material throughout the entire area of the cathode current collector, including those regions distal with respect to the tab 20 . [0025] [0025]FIG. 1 shows the transition zones between the various opening regions having a generally elliptical shape. This is not necessary. FIG. 1A shows a current collector 10 A similar in construction to current collector 10 but having the rectangular shaped openings propagating or extending from focal point 58 A on tab 20 A to transition zones 54 A and 56 A of a partial circular shape. In other words, the transition zones 54 A and 54 B are of a generally fixed radius from the focal point 58 A. In all other respects, current collector 10 A is generally similar to current collector 10 of FIG. 1. For that reason, the parts of current collector 10 A corresponding to those of current collector 10 have been given the same numerical designation, but with the “A” suffix. [0026] In a broader sense, however, the transition zone need not have an elliptical or a circular shape. It can also have an irregular shape. Furthermore, current collectors 10 and 10 A are shown having three distinct regions of openings propagating from the focal point 58 . However, according to the present invention there are at least two regions of openings, but there can be more than three regions. In any event, as the regions of openings propagate from the focal point, the openings are of a progressively smaller size. [0027] Another embodiment of the present current collector 10 B has the openings having a gradual decrease in size as the distance from the tab increases. This is shown in FIG. 1B where the parts that are the same as those of current collector 10 are given the same numerical designation, but with the “B” suffix. The openings are designated 49 A to 49 T. [0028] In a similar manner as the current collector 10 A of FIG. 1A, current collector 12 of FIG. 2 is generally similar to the current collector 10 of FIG. 1 except the openings are circular instead of rectangular shaped. Also, the circular shaped openings propagate or extend from the focal point 58 C on tab 20 C to transition zones 54 C and 56 C having partial circular shapes. For that reason, the parts of current collector 12 corresponding to those of current collector 10 have been given the same numerical designations but with the “C” suffix. [0029] It is also contemplated by the scope of the present invention that the openings need not necessarily be circular or rectangular. Instead, they can be of irregular shapes. They can also be of different shapes in the same current collector. What is important is that the size of the majority of the openings in a first zone or region closest to the current collector tab are larger than the majority of the openings in a second region further from the tab than the first region. A majority is greater than 50%. [0030] The double wing current collector 14 of FIG. 3 is essentially comprised of two current collector portions 14 A and 14 B, each similar to current collector 10 A of FIG. 1A as mirror images of each other. The mirror image current collectors 14 A, 14 B are positioned side-by-side, connected together at the third rectangular-shaped opening 52 A. [0031] [0031]FIG. 4 shows the exemplary electrochemical cell 100 useful with any one of the current collectors 10 , 10 A, 12 and 14 . For sake of clarity, the single wing collector 10 is shown. [0032] The cell includes a casing 102 having spaced apart front and back side walls (not shown) joined by sidewalls 104 and 106 and a planar bottom wall 108 . The junctions between the various side walls and bottom wall are curved. A lid 110 closes the open top of the casing 102 . Lid 110 has an opening 112 that serves as a port for filling an electrolyte (not shown) into the casing after the cell's internal components have been assembled therein and lid 110 has been sealed to the side walls. In the final and fully assembled condition, a plug, such as a ball 114 , is hermetically sealed in the electrolyte fill opening 112 to close the cell in a gas tight manner. The casing 102 , lid 110 and sealing ball 114 are preferably of a conductive material. Suitable materials include nickel, aluminum, stainless steel, mild steel, nickel-plated mild steel and titanium. Preferably, the casing, lid and sealing ball are of the same material. [0033] A terminal lead 116 for one of the anode electrode and the cathode electrode is electrically insulated from the lid 110 and the casing 102 by a glass-to-metal seal 118 . In a case-negative cell configuration, the lead 116 serves as the cathode terminal and the lid 110 and casing 102 serve as the negative or anode terminal, as is well known to those skilled in the art. A case-positive cell configuration has the positive electrode or cathode contacted to the casing 102 with the anode supported on the current collector 10 connected to the lead 116 . [0034] In either case, the exemplary cell 100 shown in FIG. 4 includes a central electrode 120 comprising the current collector 10 of the present invention supporting at least one of the opposite polarity active materials. For the sake of clarity, the active materials are not shown supported on the current collector 10 . However, in a case-negative cell configuration, current collector 10 supports opposed layers of cathode active material contacting the opposite major sides thereof locked together through its many openings. The tab 20 is then connected to the terminal lead 116 such as by welding. In a case-positive cell configuration, anode active material is locked together supported on the opposite major sides of the current collector. [0035] The central electrode 120 of cell 100 is sealed in a separator envelope 122 to prevent direct contact with the opposite polarity electrode. While not shown in FIG. 4, in a case-negative design the opposite polarity electrode is the anode comprised of anode active material contacted to the inner major sides of the current collector 14 shown in FIG. 3. The wing portions 14 A and 14 B of collector 12 are then folded toward each other at about the mid-point of the third diamond-shaped opening 52 A so that the tabs 20 A line up with each other. In a case-positive cell configuration, the opposed cathode plates are carried by the wing portions 14 A, 14 B and folded toward each other and into electrical association with the opposed major sides of the central anode. [0036] A more thorough and complete discussion of a cell construction having a current collector comprising wing-like portions that are folded into electrical association with a central electrode of an opposite polarity is shown in U.S. Pat. No. 5,312,458 to Muffoletto et al. This patent is assigned to the assignee of the present invention and incorporated herein by reference. [0037] The cell 100 can be of either a primary or a secondary chemistry. A preferred primary electrochemical cell is of an alkali metal anode, such as of lithium, and a solid cathode active material. Exemplary cathode materials include silver vanadium oxide, copper silver vanadium oxide, manganese dioxide and fluorinated carbon (CF x ) . An exemplary secondary cell has a carbonaceous anode and a lithiated cathode active material such as lithium cobalt oxide. In either type of cell chemistry, the activating electrolyte is of a nonaqueous nature. [0038] It is appreciated that various modifications to the present inventive concepts described herein may be apparent to those of ordinary skill in the art without departing from the spirit and scope of the present invention as defined by the herein appended claims.

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CROSS-REFERENCE TO RELATED APPLICATIONS [0001] This is a Non-Provisional (Utility) patent application of provisional application Ser. No. 60/572,315, filed May 18, 2004 STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT [0002] Not Applicable TECHNICAL FIELD [0003] This application relates to a system and method for providing an effective means for identification of holes or apertures in a plate, most commonly an electrical probe testing plate. BACKGROUND [0004] Circuit board testers are used for testing a variety of circuit boards or similar devices to assure that the circuit boards operate as intended. In at least one type of circuit board tester, such as Agilent Model No. 3070, Series 3, a separate device, referred to as a fixture, is used to position the circuit board such that a plurality of electrically conductive probes (which are part of, or coupled to, the tester) contact predetermined components or positions of the circuit board. The particular components or positions that are contacted by the test or probes depend on the tests that are desired. When the probes are in contact with the desired locations on the circuit board, electrical signals with predetermined parameters (e.g., predetermined magnitudes or patterns of current, voltage frequency phase and the like) are applied by the tester, typically under control of a computer, to certain probes. Some or all of the probes are used to measure the performance or response of the circuit board (i.e., to measure electrical parameters of some or all of the probes contacting the circuit board). In this way, it is possible to rapidly perform a number of tests or measurements characterizing the performance of the circuit board while simulating the conditions the circuit board would have, or could have, during actual use. Although it is possible to use these types of tests (and testing devices) for a variety of possible purposes (such as “spot checking” selected circuit boards at a production facility, testing circuit boards which may be malfunctioning, testing prototype circuit boards as part of a design program and the like), in at least some applications, circuit board testing is used to provide quality assurance on all or substantially all products of a given type or class which are produced by a company. [0005] In at least some situations, it is desired to provide a tester with probes at two or more levels with respect to a direction normal to the plane of the unit under test (UUT) e.g., by providing some probes having a first height and other probes having a second height. This arrangement affords the opportunity to perform two or more different sets of tests such that the points at which probes contact the UUT during one set of tests are different from (or a subset of) the points at which probes contact the UUT during another set of tests. Typically, in such a “dual stage” testing situation, the UUT is first positioned so as to contact all probes (and perform a first set of tests), and then positioned to contact only the taller set of probes (at points of the UUT which are determined by the location of the tall probes) and a second set of tests are performed using only the taller probes. Although many different testing procedures can be used, as will be understood by those of skill in the art, in at least some situations, the taller probes may be used for functional tests and/or boundary scan tests (such as the boundary scan tests as described in IEEE Standard No. 1149.1). [0006] In at least one previous approach, the circuit board is moved in the direction of the probes, typically causing the taller probes, which may be provided with a spring-urged telescoping structure, to partially collapse or telescope down to the level of the smaller probes, such that substantially both sets of probes (the taller probes and the shorter probes) contact the UUT at desired positions. With the board held in this position, a first set of tests (such as functional tests and/or boundary scan tests) can be performed. After tests are performed using the full set of probes the vacuum is released such that the UUT is positioned to contact only the taller probes (which telescope upwardly) and a second set of tests (such as tests directed to measuring performance or characteristics of individual components on the UUT) can be performed. [0007] The testers generally contain a plate as part of the tester that functions as a mechanical stand-off for the fixture. While the fixture is held rigidly in place against the plate, or against rigid stand-offs fastened to the plate, the probes make contact with the circuit board through various holes in the plate. The plates are usually supplied by the tester manufacturer with regularly spaced holes, usually in a rectangular grid, so that a given plate from the tester manufacturer may be used to test a variety of circuits. Even though a circuit generally requires its own custom layout for the probe locations, the plate, because of its standardized hole configuration, may be used relatively independently of the specific locations of the probes, and may also be reused when the tester is reconfigured to test a new circuit. This standardization of the hole locations reduces the number of custom parts required for a tester, and thereby reduces the cost of the system. [0008] The plates are typically molded from a plastic material, such as polycarbonate, so that the array of holes may be built right into the mold. Because they are molded, not drilled, there is no additional cost required for drilling the holes. In addition, the resulting plastic part is non-conducting, which is important for insulation of the electrically conductive probes from each other. [0009] These plates are commercially available, and a model that fits the above-mentioned Agilent circuit tester is sold as the “3070 alignment plate.” [0010] A potential drawback to a completely standardized plate is that it generally requires considerable effort to identify particular holes during the final inspection of the tester prior to usage. Typically, a technician will have to verify the location of each probe manually, by counting the row and column values of each probe (seen visually through a hole in the plate), then comparing the values to those in a published list as part of the tester layout drawings. If there are dozens of probes, all specifically located in a rectangular array that contains hundreds of identical-looking holes, this may be a very time-consuming procedure for the technician, and may lead to errors in probe placement if the technician counts incorrectly. Accordingly, it would be useful to provide a plate with simple identification features, so that a technician may readily visually identify which holes are to accept probes. [0011] One prior art solution is to manually mark each hole in the plate that will receive a probe during operation. This solution turns out to be simple in theory, but very labor-intensive, and therefore very expensive. Accordingly, it would be useful to provide a plate with simple identification features that may be identified using the same tools that provide the tester configuration drawings (reducing the possibility of human error in determining the locations.) Additionally, the identification features should be inexpensive, and not require a custom-fabricated plate for each particular circuit under test. SUMMARY [0012] The one aspect of the present invention is a plate with identification features, so that a subset of holes in the plate may be visually identified by distinguishing between holes with indicia and holes without. [0013] The invention is presented as a product and method of making. [0014] As a product, there is disclosed a probe plate have a plurality of holes and a first and second surface of a predetermined indicia, the plate having a first and second subsets of holes through the plate, the first subset and second subset being mutually exclusive. There is a second indicia applied to the second face, said second indicia being different from said predetermined indicia, so that the applied indicia is discernible from the predetermined indicia, the second indicia being absent adjacent said second subset of holes. This makes it possible to distinguish between holes of the first and second subset. [0015] As a method, there is disclosed a method of identifying specific holes in a probe plate having one side of a predetermined color and first and second subsets of probe holes. The steps in this embodiment are, covering an area adjacent said first and second holes with an indicator; and removing the indicator adjacent holes of said first subset. This permits the holes of first and second subsets can be distinguished from each other by the differential in between the color and the indicator. [0016] In a further embodiment, a first side of the plate, preferably the side opposite the fixture and circuit board during operation of the tester, is coated with a thin layer of paint, so that the area in between all the holes is generally uniformly coated. The paint is preferably colored in contrast to the unpainted color of the plate. A subset of the holes is identified, and the paint surrounding each hole in the subset is removed. [0017] Keep in mind that this summary is not meant to define the invention in any way, but to assist the reader in becoming familiar with the technology presented in the specification. The claims below define the scope of the patent, not this summary. BRIEF DESCRIPTION OF THE DRAWINGS [0018] FIG. 1 is a schematic of a prior art grooved plate with a subset of holes identified manually. [0019] FIG. 2 is a schematic of a grooved plate with a subset of holes identified according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS [0020] FIG. 1 shows a prior art interface or probe plate 1 , which contains a first face 6 , and a plurality of holes 4 . The holes 4 are drawn in a rectangular array, but it will be appreciated that the holes 4 may be configured arbitrarily on the plate 1 . As used in a circuit board tester, the plate 1 is typically built into the tester, and typically provides a mechanical surface against which parts may be held during the test procedure. A fixture that contains a circuit board under test may be placed rigidly in contact opposite the grooves 3 on the second face (not identified in FIG. 1 ) of the plate 1 , and a plurality of electrical probes access various points on the circuit board through various holes 4 in the plate 1 . During the testing procedure, the probes apply and measure various voltages and currents at specific locations in a circuit board under test, generally to ensure that the circuit performs adequately. Typically, a single probe corresponds to a single hole 4 in the plate 1 . [0021] Prior to usage of the tester, the various electrical probes must be configured to test specific locations in a particular circuit. The probe locations are typically generated at the CAD (computer assisted drafting) level, usually by the same tools that lay out the components on the circuit boards. The probe locations may be documented in CAD drawings and communicated to a technician that configures the probes manually, or may be encoded and communicated electronically to an automated device that configures the probes. [0022] Once the tester probes are properly configured and the plate 1 is attached to the tester, a subset 4 a - 4 h of the holes 4 in the plate 1 will receive probes during operation of the tester. The remainder of the holes 4 that are not in the subset 4 a - 4 h do not receive probes during operation of the tester. It will be appreciated that the number and locations of the holes in subset 4 a - 4 h depend on the circuit under test, and are relatively unimportant for the present invention. [0023] The final step in the manufacturing process for the prior art plate 1 is a manual identification of the subset 4 a - 4 h of holes 4 that receive probes. The manufacturer of the prior art plate 1 then manually marks each hole 4 in the subset 4 a - 4 h by hand, typically by painting (i.e. using an indicator (indicia)) a small area around each hole 4 in the subset 4 a - 4 h on the first face 6 . Thus, it is the painted areas which are to have probes inserted. Although the marked areas surrounding each hole 4 in the subset 4 a - 4 h are drawn as circular in FIG. 1 , it will be appreciated that the markings may be of any shape or pattern, as long as each marking is readily identifiable with exactly one hole 4 in the subset 4 a - 4 h . They do not have concentric paint markings. The indication or indicator marking can be adjacent the hole, so long as it is clear which hole is referred to. [0024] A severe drawback to the manual marking system of the prior art plate 1 is that it is very labor-intensive, and therefore very expensive. For a plate 1 that requires dozens of markings, in an array with hundreds of holes, the marking procedure can be quite significant, and in some cases, can be the greatest expense in producing the plates 1 . [0025] Although one may be tempted to fabricate a new plate for each circuit under test, with holes only where probes are placed, this would be expensive and largely impractical. The prior art plate 1 is generally molded from a plastic material, such as polycarbonate, and has its holes incorporated into the mold itself. A custom prior art plate 1 molded in this manner, with holes only where required by the user, would require a custom mold for each user, which is impractically expensive. Additionally, the drilling of holes in a blank plate, while possible, is also more expensive than the prior art technique of manually marking the holes. Accordingly, there is a need for a plate that has a large number of holes for flexibility, but has a way of inexpensively identifying a subset of the holes to simplify the final inspection of the tester. [0026] FIG. 2 shows a plate 11 in an embodiment of the present invention. A coating 15 is applied to a first face 16 of an uncoated plate 12 , preferably in the area (grooves) between the ridges 13 . The outwardly extending ridges 13 may be coated as well, but at the risk of flaking or peeling of the coating 15 . The uncoated plate 12 contains a plurality of holes 14 , and the coating 15 does not fill in the holes 14 . The coating 15 may be a paint, a two-part epoxy, or an other opaque coating, preferably of a color of a high contrast with the color of the uncoated plate 12 . Preferably, the coating 15 is not electrically conductive. For example, if the uncoated plate 12 is dark-colored, a suitable coating 15 may be commercially available; “Polane T-White” paint. The paint 5 is preferably in high contrast to the unpainted color of the bare plate 2 . For example, if the bare plate 2 is a dark-colored polycarbonate material, then the paint or ink 5 should be a light color (any contrasting color will do), so that the marked holes 4 are readily visibly detected, by eye or by a machine vision system. [0027] In the case where a drilling machine will remove the paint, which is the preferred solution, we have found that it is important to match the paint with the base material very carefully. In initial attempts, we found that the drill would not only scrape a circular hole, but also cause the paint to chip and remove paint from adjacent holes. Vibration might also cause the paint to flake. The preferred base material is a hard plastic, so a paint which adheres well (such as that mentioned above) should be chosen and tested. Thus in our preferred solution, the indicator, or paint applied to the base plate should fixedly adhere thereto, so that when being drilled, scraped or otherwise removed to as the hole marker. [0028] In a subset 14 a - 14 h of holes 14 , the coating 15 has been removed in the region around each hole 14 in the subset 14 a - 14 h , exposing the first face 16 underneath. Because the coating 15 contrasts with the color of the uncoated plate 12 , each hole 14 in the subset 14 a - 14 h is readily visually identifiable, whether by eye or by a camera in a machine vision system. [0029] Preferably, the removal of the coating around each hole 14 in the subset 14 a - 14 h is performed by an automated tool, such as an automated drill that receives a set of subset 14 - 14 h locations from a CAD file. The automated drill preferably uses a drill bit larger than the hole 14 diameter, and drills only enough material to completely remove the coating 15 , without substantially drilling through the first face 16 . For example, if the coating 15 has a thickness of roughly 0.1 mm, then the drill may remove roughly 0.5 mm of material. The uncoated plate 12 may be substantially thicker than 0.5 mm. Note that drilling such shallow holes is an inexpensive procedure compared to drilling comparable through holes, and that very little waste material is produced. Additionally, if the user decides to add another hole 14 to the subset 14 a - 14 h , he may mark the added hole by hand, simply by turning a drill bit centered in the hole by hand and grinding for a few seconds; the coating 15 comes off readily. [0030] It will be understood that the grooves 13 on the plate 11 are not essential for the present invention. A similar coating 15 may be applied to an uncoated plate that has physical features other than grooves, such as posts, or has no physical features at all. The coating 15 may be applied to the regions between holes 14 , so that when removed, the hole may be readily visibly identified by eye or by a machine vision system as part of the subset 14 a - 14 f. [0031] As used in a circuit board tester, the plate 11 of FIG. 2 would readily identify the subset 14 a - 14 h of holes 14 that receive probes during operation. Because of the high contrast between the coating 15 and the color of the uncoated plate 12 , the technician easily sees the exposed first face 16 in the regions around each hole 14 in the subset 14 a - 14 h , and can then quickly complete the final inspection of the probe locations prior to operation. If the technician finds any holes 14 in the subset 14 a - 1 4 h that are missing a probe, or finds a probe in a hole 14 that is not in the subset 14 a - 14 h , he can take corrective actions. Because the entire subset 14 a - 1 4 h is visible all at once to the technician, without the need for manually counting rows and columns, the efficiency of the inspection process is greatly improved. [0032] Typically, when a tester is customized to test a particular circuit, a set of drawings is made by a computer assisted drawing (CAD) machine, well known in the art, and presented to a technician. The technician uses the drawings to configure the tester, and the drawings typically indicate the locations and types of the probes. Alternatively, the CAD machine may generate an automated set of instructions for placement of the probes during assembly of the tester. In the present invention, the CAD machine may generate an additional set of instructions for denoting which holes in the plate are to receive probes. The additional instructions may be used by an automated drilling machine that ablates or scrapes off the paint in the area surrounding each hole that receives a probe. The drilling machine uses a drill bit of a larger diameter than the hole, and only drills until the paint is removed; it does not drill substantially into the plate itself and does not increase the diameter of the hole. [0033] Once the paint is removed around a particular hole, the hole is readily identified visually, either by eye or by use of a machine vision system. “Visual” in this context there is not limited to vision related detection. It includes optical and non optical methods. It can also include machine-readable detection/recognition, tactile detection, by creating ridges, depressions, etc. Once the tester is configured, each hole in the subset should contain a probe, and no probes should be present in holes not contained in the subset. Once all the probes are configured, a final visual inspection of the tester is relatively simple, as the technician may simply look at the plate and ensure that each hole in the subset has a probe that extends through it, and that none of the probes extend through holes not in the subset.

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