Patent Abstract:
A barrier system acts to gradually decelerate and arrest low-flying projectiles, such as RPGs, to reduce the likelihood of a fuze-detonating impact. The barrier system, which includes a frame-supported net and net suspension, preferably with energy absorbing characteristics, preferably is modular and portable so that similar barrier units can be arranged, and optionally joined together, to form a wider line of defense, such as a defensive perimeter around a potential target area.

Full Description:
[0001]    This application claims the benefit of U.S. provisional application No. 60/620,353, filed Oct. 21, 2004, which is incorporated herein by reference. 
     
    
     BACKGROUND 
       [0002]    This invention relates to weapons defense, in particular to defense against low-flying projectiles, such as rocket propelled grenades and shrapnel. 
         [0003]    Protective arrangements have been devised to limit the destructive effect of exploding weaponry. For example, the 1943 patent to Wesseler (U.S. Pat. No. 2,326,713) discloses knitted wire shielding fabric “for minimizing the destructive effects of bombs, torpedoes and similar elements of warfare.” One form of Wesseler&#39;s shielding fabric is described as having “missile deflecting capacity.” Deflection systems also are disclosed by Corrado (U.S. Pat. No. 1,204,547) (torpedoes); Fitch (U.S. Pat. No. 4,625,668) (missiles); Feitosa (U.S. Pat. No. 2,100,211) (aerial bombs); Zuckermann (U.S. Pat. No. 2,347,653) (aerial bombs); Hume (U.S. Pat. No. 2,348,387) (aerial bombs); and Schwab (U.S. Pat. No. 2,351,297) (aerial bombs). 
         [0004]    Nowadays armed conflict in various parts of the world often involves the use of manually portable launchers that fire rocket propelled grenades (“RPGs”) or similar warheads that are designed to explode upon impact. Such “low-flying” warheads travel at relatively. low velocity (as compared to bullets, for example) and typically approach a ground-based target at a relatively low angle of elevation (as compared to aerial bombs, for example, which are dropped from aircraft). Detonation of such low-flying warheads typically is effected by impact pressure on a fuze. Some have a back-up time delay system that detonates the warhead after a preset period of time. 
         [0005]    Often it is necessary to protect personnel and/or materiel at particular locations from the threat posed by RPGs and other low-flying projectiles, which could include non-explosive projectiles as well as explosive warheads. The need for such protection is acute in open terrain and shipboard situations, where there are no natural or man-made barriers (e.g., berms or walls) that would otherwise afford protection. This invention is designed to provide an effective protection system against low-flying projectiles. 
       SUMMARY OF THE INVENTION 
       [0006]    As RPGs and other low-flying warheads are designed to explode upon impact, the present invention aims to inhibit the likelihood of such explosions preferably by preventing the detonating impact. To prevent the impact, the warhead is “caught” in flight or deflected by a net-like barrier that gradually decelerates the warhead so that it remains intact. If the warhead does explode upon impacting the barrier or after it drops to the ground, substantial blast protection is afforded by the barrier itself, which preferably is deployed at a safe distance from personnel and materiel, thus considerably reducing or eliminating the destructive effect of the blast. 
         [0007]    The projectile is caught or deflected by a barrier that has a net suspended on a ground- or floor-supported frame, which also restrains the bottom margin of the net. Either or both of the top and bottom margins may be resiliently restrained. The side margins of the net preferably are unrestrained, and the net preferably is wider than the frame. Depending on the angle and/or the velocity of the projectile, kinetic energy of the projectile is absorbed by means of net flexion, frame flexion, and/or action of any resilient net restraint. After the projectile is arrested or deflected, the barrier substantially returns to its original position to afford continued protection. The frame preferably has a clear space behind the net to accommodate rearward net deflection by the projectile substantially without interference by the frame. The frame optionally can be adjustable so as to enable adjustment of the angle of the net relative to the vertical in order to tailor the installation to surrounding circumstances for optimum protection, i.e., to minimize the likelihood that warheads fired from particular locations will ride up and over the top of the net. 
         [0008]    The term “net” as used herein is defined as an expanse of any flexible material, e.g., fabric or screening or the like, having sufficient strength and small enough mesh size to at least arrest or deflect (i.e., prevent passage of) an unexploded, low-flying warhead. For optimal protection, the net optionally and preferably should have the properties of a blast curtain, i.e., sufficient strength and small enough mesh size to resist the force of a localized warhead explosion and substantially prevent the passage of small fragments of shrapnel. 
         [0009]    The barrier is modular and is readily portable so that it can be easily transported to and deployed in potentially hostile locations, either on land or on the deck of a ship. Users can erect the barrier system&#39;s modular units as needed, e.g., side-by-side to create a wide line of defense or a continuous barrier for perimeter protection around a potential target area, preferably with the nets of adjacent barrier units overlapping. Barrier height can be customized to suit any application. If desired, the barrier units can be anchored to the ground or floor, or to the deck of a ship, and adjacent units can be connected to one another. 
         [0010]    The above and other features, aspects and advantages of the invention will become more apparent from the following detailed description of exemplary embodiments shown in the accompanying drawing figures. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWING 
         [0011]      FIG. 1A  is a perspective view of a first embodiment of a barrier unit according to the invention for protection against low-flying projectiles. 
           [0012]      FIG. 1B  is a perspective view of the barrier unit shown in  FIG. 1A , illustrating flexure of the frame and the net as a low-flying projectile is intercepted. 
           [0013]      FIG. 2A  is perspective view of a second embodiment of a barrier unit according to the invention. 
           [0014]      FIG. 2B  is a perspective view of the barrier unit shown in  FIG. 2A , illustrating flexure of the frame and the net as a low-flying projectile is intercepted. 
           [0015]      FIG. 3A  is perspective view of a third embodiment of a barrier unit according to the invention. 
           [0016]      FIG. 3B  is a perspective view of the barrier unit shown in  FIG. 3A , illustrating flexure of the frame and the net as a low-flying projectile is intercepted. 
           [0017]      FIG. 4  is a perspective view of a fourth embodiment of a barrier unit according to the invention. 
           [0018]      FIG. 5  is a perspective view of a fifth embodiment of a barrier unit according to the invention. 
           [0019]      FIG. 6  is a perspective view of a sixth embodiment of a barrier unit according to the invention. 
           [0020]      FIG. 7  is a perspective view of a seventh embodiment of a barrier unit according to the invention. 
           [0021]      FIG. 8  is a perspective view of a plurality of barrier units of the type shown in  FIG. 6 , arranged to form a barrier system along a line of defense. 
           [0022]      FIG. 9  is a top plan view of the arrangement of  FIG. 8 . 
           [0023]      FIG. 10  is a side elevational view of an adjustable frame portion that enables angular adjustment of the net. 
       
    
    
     DETAILED DESCRIPTION  
       [0024]    The same reference numbers are used throughout the drawing figures to refer to the same or like parts in the different embodiments. In the figures the net is illustrated as being “see-through,” i.e., as translucent or transparent. This is done merely to be able to depict structure that is behind the net without having to eliminate or break away substantial portions of the net. The actual light-transmitting characteristics of the net will depend, of course, on the color, mesh size and chemical makeup of the net material. 
         [0025]    A first embodiment of a barrier system unit for protection against low-flying projectiles is shown in  FIGS. 1A and 1B . The barrier unit  100  includes a frame  102  and a net  104 . The frame  102  includes a plurality of base members  106 ,  108 ,  110 ,  112  in the form of flexible rods that are interconnected by means of brackets  113 . Specifically, there are front  106  and rear  108  base members and left  110  and right  112  side base members. These base members  106 ,  108 ,  110 ,  112  fit into appropriately sized hollow sockets  115  carried by the brackets  113 . 
         [0026]    Stabilizers  114  project rearwardly from sockets  115  on the two rear brackets  113 . Stabilizers  114  are designed to keep the barrier unit  100  from tipping backwards or flipping over when impacted by a low-flying projectile  130 . The underside of each bracket  113  may be provided with a rubbery coating or pad to minimize sliding on hard surfaces, and/or cleats to minimize sliding on sand or soil. At least one hole may be provided in each bracket  113  through which a spike may be driven in order to anchor the barrier unit to the ground. Sandbags may be placed on brackets  113  for stability, irrespective of whether spikes are used. 
         [0027]    Flexible side arch members  116 ,  118  of the frame  102  project upwardly and forwardly from the rear brackets  113 . The upper ends of the arch members  116 ,  118  support hollow axles  117 , each of which carries a pair of pulleys  124 . A crossbar  120  interconnects axles  117 . As later described, the side-facing sockets  115  on brackets  113 , and the hollow axles  117 , make this a modular system so that a plurality of barrier units  100  can be interconnected or otherwise juxtaposed to form a wider line of defense. 
         [0028]    The pulleys  124  guide cables  126  that are resiliently extensible by means of elongated coil springs  128 , which exert a retractive force on the cables. Each spring  128  can be located intermediate the ends of the cable, or at its lower (rear) end, as shown. The lower end of each spring  128  (or lower end of each cable  126 ) may be connected to a respective rear base member  108  as shown, or to a rear bracket  113 , or to a stabilizer  114 . The other (upper) end of each cable  126  is connected to a net bar  122 . Net  104  is anchored along its top margin to net bar  122 , which acts as a stiffener for the top margin of the net, and is anchored along its bottom margin to front base member  106 . 
         [0029]    In the ready state ( FIG. 1A ), the net bar  122  is disposed substantially above the front base member  106 . In an activate state (i.e., when a low-flying projectile  130  impacts the barrier unit  100 —see  FIG. 1B ), the load applied to the net results in a downward and rearward pull on net bar  122  and, accordingly, a pull on cables  126  and a stretching of springs  128 . This causes side arch members  116 ,  118  to bend downwardly, which moves axles  117 , pulleys  124  and crossbar  120  downwardly and forwardly. The result is that net bar  122 , although lowered, remains positioned generally above the front base member  106 . The projectile thus is kept from riding up and over the top of the net. 
         [0030]    Several mechanisms act to absorb the kinetic energy of the projectile  130  and gradually reduce its velocity until it is arrested so as to reduce the likelihood of an impact-triggered detonation. These include flexion of the net  104 , downward motion of net bar  122 , bending of the arch members  116 ,  118 , and extension of the springs  128 . When the projectile  130  is arrested, it drops to the ground in front of the net  104  with insufficient force to trigger detonation. The barrier unit  100  returns substantially to its ready state by virtue of the restorative nature of the net  104 , the flexible arch members  116 ,  118  and the springs  128 . 
         [0031]    In the case of a projectile that has a back-up time delay system, the arrested warhead would be expected to explode after it drops to the ground in front of the net. However, the barrier system still would afford a good measure of protection for personnel and materiel behind the net because the net would act as a blast curtain, and forestall the blast at a reasonably safe distance from the assets to be protected. 
         [0032]    The various components of the barrier unit may be made of a variety of suitable materials, and in suitable sizes, as follows. The net  104  preferably is made of a blast-resistant material, preferably of a mesh size small enough to block the passage of flying fragments from an exploding warhead. Examples include but are not limited to polyethylene or aramid fiber, which may be uncoated, or may be coated with polyvinyl chloride; and polyethylene-wrapped stainless steel cord. A commercial example is that disclosed in U.S. Pat. No. 5,915,449, which is incorporated herein by reference. The net preferably is about 10 to 30 ft. wide by about 10 to 30 ft. high. Brackets  113  are plate-like in form and cover an area about 1.0 ft 2  to 3.0 ft 2 . They preferably are made of steel or aluminum. Base members  106 ,  108 ,  110 ,  112 ; crossbar  120 ; net bar  122 ; arch members  116 ,  118 ; sockets  115 ; and axles  117  are about 1½ to 2½ in. in diameter, and are made of any suitably strong and flexible material, such as steel, aluminum, fiberglass, or carbon fiber. Spring rates are chosen to allow a desired degree of net deflection for the anticipated threat, and will depend on net material, net size, and frame flexion, as will be understood by those skilled in the art. For wider nets one or more intermediate cable and pulley sets could be added to provide added support. 
         [0033]      FIGS. 2A and 2B  show an alternative embodiment of barrier unit  200  in which hanging weights  228  on the rear (lower) ends of the cables  226  are used in lieu of the springs  128  used in the first embodiment. In this embodiment, the arch members  216 ,  218  are provided with intermediate stub axles  217  that support secondary pulleys  224 . The primary pulleys  124  (on axles  117 ) and the secondary pulleys  224  guide the cables  226  that extend between the net bar  122  and the weights  228 . The weights preferably are in the range of 5 to 75 lbs., and may take any form (e.g., sandbags) that can be conveniently attached to cables  226 . 
         [0034]    The operation of this barrier unit  200  is similar to the previously described unit  100 . Specifically, in the ready state, the net bar  122  is disposed substantially above the front base member  106 . In an activate state (i.e., when a low-flying projectile  130  impacts the barrier unit  200 ), the load applied to the net results in a downward and rearward pull on net bar  122  and, accordingly, a pull on cables  126  and a tendency to raise weights  228 . This causes side arch members  216 ,  218  to bend downwardly, which moves axles  117 , pulleys  124  and crossbar  120  downwardly and forwardly. The result is that net bar  122 , although lowered, remains positioned generally above the front base member  106 —again to keep the projectile from riding up and over the top of the net. 
         [0035]    In this embodiment, the kinetic energy of the projectile  130  is absorbed by means of flexion of the net  104 , downward motion of net bar  122 , bending of the arch members  216 ,  218 , and elevation of the weights  228 . When the projectile  130  is arrested, it drops to the ground in front of the net  104  with insufficient force to trigger detonation. The barrier unit  200  returns substantially to its ready state by virtue of the restorative nature of the net  104 , the flexible arch members  116 ,  118  and the weights  228 . Weight size is chosen to allow a desired degree of net deflection for the anticipated threat, and will depend on net material, net size, and frame flexion, as will be understood by those skilled in the art. 
         [0036]      FIGS. 3A and 3B  show another alternative embodiment of barrier unit  300  in which spring-loaded spools  324  are carried on axles  117 . The spools  324  have internal torsion springs  328  (not shown), which are substitutes for the springs  128  of the first embodiment, and for the weights  228  of the second embodiment. These internal torsion springs  328  apply a retractive force to cables  326 , which are wound in or on spools  324  and support the net bar  22  so that the net  104  is held generally upright. Each torsion spring may be in the form of a spiral (i.e., clock-type), but any form of torsion spring may be used. The torsion spring may be supplemented with a damper to help dissipate energy during active use. Commercially available dampers that are suitable include those that employ friction disks, and those that employ a fluid forced through one or more orifices or past a series of vanes. 
         [0037]    The operation of this barrier unit  300  is similar to the previously described barrier units  100 ,  200 . Specifically, in the ready state, the net bar  122  is disposed substantially above the front base member  106 . In an active state (i.e., when a low-flying projectile  130  impacts the barrier unit  200 ), the load applied to the net results in a downward and rearward pull on net bar  122  and, accordingly, a pull on cables  326 . As cables  326  pay out from spools  324 , torsion springs  328  tighten. This causes side arch members  116 ,  118  to bend downwardly, which moves axles  117 , spools  324  and crossbar  120  downwardly and forwardly. The result is that net bar  122 , although lowered, remains positioned generally above the front base member  106 —again to keep the projectile from riding up and over the top of the net. 
         [0038]    In this embodiment, the kinetic energy of the projectile  130  is absorbed by means of flexion of the net  104 , downward motion of net bar  122 , bending of the arch members  116 ,  118 , and tightening of the torsion springs  328  as the cables  326  pay out. If the spools  324  are equipped with dampers as described above, the dampers serve to dissipate additional energy. When the projectile  130  is arrested, it drops to the ground in front of the net  104  with insufficient force to trigger detonation. The barrier unit  300  returns substantially to its ready state by virtue of the restorative nature of the net  104 , the flexible arch members  116 ,  118  and the torsion springs  328 . Torsion spring rates are chosen to allow a desired degree of net deflection for the anticipated threat, and will depend on net material, net size, frame flexion, and the effect of dampers, if present, as will be understood by those skilled in the art. 
         [0039]    Any of the above embodiments can be modified so that the bottom margin of the net, instead of being firmly anchored to the frame, is resiliently restrained, e.g., by cables with springs in the manner of the embodiments of  FIGS. 4-7 . With such an arrangement, the top margin of the net can be resiliently restrained as disclosed above; alternatively the net can be suspended from the frame with its top margin firmly anchored to the frame. 
         [0040]    As noted earlier, the barrier system of the invention is modular so that multiple units can be interconnected to form a wider line of defense. To facilitate this, each of the brackets  113  has a side-facing socket  115  that is designed to be connected to a corresponding element of an adjacent barrier unit. Similarly, the side-facing portion of each axle  117  is designed to be connected to a corresponding element of an adjacent barrier unit. As a result, multiple barrier units  100 ,  200 ,  300  can be joined side-by-side. A degree of flexibility in the base members  106 ,  108  and the crossbar  120 , and in their connections to sockets  115  and  117 , respectively, allows a series of interconnected barrier units to arc around an area so as to form a partial or full protective perimeter. Preferably, angled or other types of connectors (not shown) could be used to couple adjacent barrier units together. 
         [0041]    It is possible to stitch or otherwise attach filler nets (not shown) to the adjacent nets of the joined barrier units in order to reduce the likelihood of projectile penetration at the lateral margins of the nets. However, it is preferred to use nets and net bars that are wider than those illustrated and described in the above embodiments. In that case, the cables  126 ,  226 ,  326  of the respective embodiments could be guided by the outer pair of pulleys  124  or the outer pair of spools  324 ; alternatively, the outer pair of pulleys or spools could be dispensed with and the net bar and net would extend laterally outwardly further from the supporting cables. Adjacent barrier units would be staggered so that the nets overlap in a manner similar to that shown in  FIGS. 8 and 9  and described below in connection with the embodiments of  FIGS. 6 and 7 . 
         [0042]    Further embodiments of the invention are illustrated in  FIGS. 4-8 . These embodiments use a net material as disclosed above, but employ a more robust frame than the previously described embodiments, the frame thus being more suitable for supporting a larger net and/or standing up to harsher conditions. 
         [0043]    The barrier unit  400  depicted in  FIG. 4  has a net  402  with a top margin  404 , a bottom margin  406 , and side margins  408 . The top margin  404  is secured to a top net bar  410 . The bottom margin  406  is secured to a bottom net bar  412 . The net bars  410 ,  412  are similar in construction to net bar  122  above ( FIG. 1A ), and serve to stiffen the top and bottom margins  404 ,  406 . The net  402  with its net bars  410 ,  412  is suspended from a frame  420  by means of three cables  450  that are attached to top net bar  410 . The bottom margin of the net is restrained by the frame by means of three cables  470 . 
         [0044]    Frame  420  may be made of any of the materials mentioned above in connection with the previously described embodiments. The frame components could be designed to have a degree of flexibility that enables them to be a meaningful factor in energy absorption, but preferably they are more rigid than those of the previously described embodiments. The frame components may be welded or otherwise secured together, but preferably most or all of them they are knock-down in design (bolted, clamped or otherwise removably connected) so that the unit can be transported compactly and easily and assembled on-site. Frame  420  has a ground- or floor-engaging base portion comprising three laterally spaced longitudinal bottom bars  422  interconnected by two lateral bottom ties  424 . Each bottom bar  422  has secured to it a front plate  426 , a center plate  428  and a rear plate  430 . These plates may have holes through which spikes may be driven in order to anchor the unit to the ground. Each of the front and rear plates  426 ,  430  has three stabilizers  432  that extend forwardly and rearwardly, respectively, to enlarge the effective footprint of the unit. 
         [0045]    Frame  420  also has an upper portion comprising three laterally spaced longitudinal top bars  434  interconnected by two lateral top ties  436 . The upper portion is supported on the base portion by means of three spaced upright portions, each comprising a front post  438 , an angled and bent rear strut  440 , and four stabilizer struts  442 . The front ends of top bars  434  are cantilevered and are disposed substantially forward of posts  438  and above front plates  426  so that net  402  hangs substantially vertically, with ample deflection space behind it. 
         [0046]    Each cable  450  suspending top net bar  410  is guided by a frame-mounted front pulley  452  at or near the front end of top bar  434 , and a frame-mounted rear pulley  454  at or near the top of post  438 . Cable  450  is anchored to the frame via a coil spring  456 , which places the cable under initial tension and renders it resiliently extensible. Similarly, each cable  470  restraining the bottom net bar  412  is guided by a frame-mounted front pulley  472  at or near front plate  426 , and a frame-mounted rear pulley  474  on bottom bar  422  behind post  438 . Cable  470  is anchored to the frame via a coil spring  476 , which places the cable under initial tension and renders it resiliently extensible. Spring rates are chosen to allow a desired degree of net deflection for the anticipated threat, and will depend mostly on net material and net size (the frame flexion factor should be minimal given the robust nature of the frame). A suspended weight, a torsion or other type of spring, a gas spring, or any other element or unit that applies a restorative force (and optionally a damping force) to each cable may be substituted for the coil springs in this or any other embodiment. 
         [0047]    The front ends of top bars  434  optionally may be made adjustable in length so as to adjust the fore/aft position of pulleys  452  and, hence, the fore/aft position of top margin  404  of the net, to vary the angle of the net relative to the vertical. This is illustrated by dashed lines and reference number  435  in  FIG. 4  for just one of the top bars  434 , it being understood that a frame having this adjustment feature will necessarily require that all top bars  434  be adjustable in this manner. This adjustment feature may be incorporated into this or any other embodiment of the barrier unit. Adjustment of the fore/aft position can be accomplished by any suitable structure. For example, as illustrated in  FIG. 10 , each top bar  434  may have a movable telescoping front portion  434   a  that can be extended forwardly from the fixed portion  434  and be secured in a selected position by means of a shear pin or pins (not shown) placed in aligned holes  435   b  in the fixed ( 434 ) and movable ( 434   a ) telescoping portions. Other examples of length-adjustable members are well-known to those skilled in the art, and include telescoping members with locking clutch collars; telescoping threaded members; and hinged, foldable extensions, to name just a few. 
         [0048]    When a projectile impacts net  402 , the net will deflect rearwardly due to net flexion and the extension of springs  456 ,  476 , all of which serve to absorb the kinetic energy of the projectile in a manner similar to the operation of the embodiment of  FIGS. 1A ,  2 A, arresting the projectile and causing it to drop to the ground in front of the net. However, by comparison much less kinetic energy would be absorbed through frame flexion due to the more robust construction of the frame of this embodiment. 
         [0049]    This embodiment and those described below can be modified so that the net is suspended from the frame with its top margin firmly anchored to the frame. Alternatively, the bottom margin of the net can firmly anchored to the frame. In either case, the other margin of the net would be resiliently restrained as disclosed. 
         [0050]    The embodiment of  FIG. 5  is similar to that of  FIG. 4 . The differences reside in the base portion of frame  500 , in which each bottom bar  522  has three depending legs  532 , which are intended to be buried in the ground to stabilize the unit. One or more apertured plates  528  also may be provided on each bottom bar  522 . 
         [0051]    The embodiment of  FIG. 6  is similar to that of  FIG. 4 , but employs a modified net  602  that is wider than the frame  600 . Protrusion of the net laterally beyond the sides of the frame facilitates deployment of a more effective multi-unit barrier system because the nets of adjacent units can be overlapped. Top net bar  610  and bottom net bar  612  preferably are as wide as net  602 . Note that the lateral cables  650 ,  670  are located inboard of the ends of the net bars  610 ,  612 . It is possible for the unit to be configured so that only one side of the net projects beyond the frame, but the symmetrical arrangement illustrated in  FIG. 6  provides more flexibility in terms of configuring an effective barrier system. 
         [0052]    The embodiment of  FIG. 7  has the combined attributes of the embodiments of  FIGS. 5 and 6 . Depending legs  732  can be buried in the ground for stability, while a symmetrical net assembly  702 ,  710 ,  712  wider than the frame allows for net overlap in a barrier system. 
         [0053]      FIGS. 8 and 9  depict a barrier system deployed with the nets  602  of adjacent units overlapping one another (units  600  according to the embodiment of  FIG. 6  are used as an example). The units are shown in alternating positions, which defines a substantially straight barrier. The units could also be placed in stepped positions (each one slightly behind the preceding one) so that the net faces continuously recede. In either case the units can be angled so as to form a generally arcuate barrier. Adjacent units optionally can be joined together by suitable links  902  (only two are shown in  FIG. 9 ) for added stability of the barrier system as a whole. Links  902  can be placed at ground level and/or above ground level. They can take any suitable form that will help keep adjacent units from separating or shifting. Examples include but are not limited to bars clamped or bolted to the frames, and cables or chains encircling or otherwise secured to frame members, to name just a few. 
         [0054]    The invention is not limited to the above-described embodiments, and it will be understood by those skilled in the art that various modifications can be made without departing from the scope of the invention, which is defined by the appended claims.

Technology Classification (CPC): 5