BACKGROUND

[0001] Vehicle impact safety is assessed at crash test facilities. For instance, a guidance system within a crash test facility may pull a vehicle (e.g., a car, a truck, a movable deformable barrier (MDB), etc.) up to speed, and the vehicle impacts a target (e.g., another vehicle, a pole, a barrier, etc.) while traveling at the speed, as specified by regulation or otherwise. During a crash test, cameras are used to capture video and/or still images of the vehicle to assess the impact safety of the vehicle. To this end, many crash test facilities use film pits disposed at the impact location(s) to capture video and/or still images of the underbody of the vehicle during a crash test, as the vehicle’s underbody cannot be adequately observed using above-ground cameras.

BRIEF DESCRIPTION OF THE DRAWINGS

[0002] FIG. 1 illustrates an example system for securing a cover sheet to a panel using a vacuum attachment technique, the panel being configured to cover at least a portion of a film pit of a vehicle crash test facility.

[0003] FIG. 2 illustrates a vehicle above a film pit of a vehicle crash test facility.

[0004] FIG. 3 illustrates a film pit of a vehicle crash test facility.

[0005] FIG. 4 illustrates a support framework disposed in a film pit of a vehicle crash test facility.

[0006] FIG. 5A illustrates a cross-sectional view of a portion of the example system of FIG. 1.

[0007] FIG. 5B illustrates a cross-sectional, exploded view of a portion of the example system of FIG. 1.

[0008] FIG. 5C illustrates a cross-sectional view of the portion of the example of FIG. 1 illustrated in FIG. 5B with the cover sheet secured to the panel.

[0009] FIG. 6A illustrates a cross-sectional, exploded view of a portion of another example system for securing a cover sheet to a panel using a vacuum attachment technique. FIG. 6A depicts a fluid path that extends from a port on a side of the panel to an opening in a top of the panel.

[0010] FIG. 6B illustrates a cross-sectional, exploded view of a portion of another example system for securing a cover sheet to a panel using a vacuum attachment technique. FIG. 6B depicts a fluid path that extends from a port on a top of the cover sheet to an opening in a bottom of the cover sheet.

I [0011] FIG. 7 illustrates an example system including multiple cover sheets secured to multiple panels via a pump that is configured to be connected to respective ports for selectively drawing and/or removing vacuum associated with individual ones of the multiple panels.

[0012] FIG. 8 illustrates a flow diagram of an example process for securing a cover sheet(s) to a panel(s) using a vacuum attachment technique, the panel(s) being configured to cover at least a portion of a film pit of a vehicle crash test facility.

DETAILED DESCRIPTION

[0013] In order to capture images of the underbody of a vehicle during a crash test, many crash test facilities have film pits disposed at the impact location(s) where the vehicle impacts a target. A support framework may be disposed in the film pit to support one or more transparent panels, and, in some scenarios, a guide rail that is used to guide the vehicle along a path (e.g., a linear path) as the vehicle is pulled up to speed and the vehicle impacts the target at the speed. The panels (sometimes referred to herein as “windows”) are configured to cover the film pit in order to provide a surface that vehicles can be driven over to impact the target. Because the panels are transparent, camera(s) in the film pit are able to capture images of a vehicle (e.g., the vehicle’s underbody) when the vehicle is positioned directly above the film pit. Due to the cost of the panels, and due to the violent nature of crash testing, replaceable, transparent cover sheets - which are much less expensive than the panels - are secured to the tops of the panels and used as a sacrificial layer to protect the underlying panels from damage during crash testing. As the cover sheets accrue damage from tires or other vehicle components that contact (e.g., slide across) the surface of the cover sheets, the cover sheets are replaced, as needed, to restore visibility for the film pit camera(s) and to extend the useful life of the panels that cover the film pit.

[0014] In order to prevent the cover sheets from sliding under the force of a skidding tire during a crash test, the cover sheets are typically secured to the panels using fasteners (e.g., screws, bolts, etc.), by clamping around the perimeter of the panels/cover sheets, or by a tight fit around the perimeter of the panels/cover sheets. A sliding cover sheet can influence the way a vehicle moves during a crash test and can even render the crash test worthless. The underlying panel, which is typically quite expensive, is also at greater risk of being damaged if the cover sheet slides under a load. However, efforts to secure cover sheets to underlying panels using fasteners have several drawbacks. For instance, if too few fasteners are used, a cover sheet may be inadequately secured to the underlying panel, and the cover sheet may slide during a crash test notwithstanding the use of fasteners. On the other hand, if too many fasteners are used, the field of view of the film pit camera(s) may be occluded by the numerous fasteners, not to mention the cost and labor involved in replacing a cover sheet is greater when more fasteners are used, as compared to the cost and labor involved in replacing a cover sheet that is secured to an underlying panel with fewer fasteners. The machining (e.g., drilling holes in the cover sheets and the panels, threading the holes, etc.) involved in using the fasteners creates stress risers and structural weaknesses in the cover sheets and the panels. Moreover, the use of fasteners creates leak paths where liquid (e.g., vehicle liquid released during the impact of the vehicle during a crash test) leaks into the leak paths and drips onto the items (e.g., cameras, lights, etc.) below the panels. Oftentimes liquid is drawn between the panels and the cover sheets by capillary action, which further occludes the field of view of the film pit camera(s). As a result of the leak paths caused by the use of fasteners, frequent and laborious maintenance has to be performed in order to clean the panels, the cover sheets, and the items (e.g., cameras, lights, etc.) in the film pit.

[0015] Disclosed herein are, among other things, techniques, devices, and systems for using a vacuum attachment technique to secure cover sheets to panels, the panels being configured to be part of a roadway (e.g., to cover a film pit) of a vehicle crash test facility. In this manner, the use of conventional mechanical attachment can be avoided. In an example implementation, a roadway (e.g., a concrete roadway) of a vehicle crash test facility includes a recess(es) for receiving one or more transparent panels for the purpose of photography and/or visual observation of a crash. In some examples, the recess(es) defined in the roadway is a film pit. . In some examples, the film pit includes a support framework for supporting the one or more transparent panels that are configured to cover the film pit. One or more transparent cover sheets are configured to be disposed on the one or more panels. In some examples, the cover sheets can be devoid of holes or other features that may otherwise occlude the field of view (e.g., of one or more cameras) disposed in the film pit underneath the panel (s). Accordingly, visibility (e.g., for the camera(s)) is improved by the techniques, devices, and systems described herein, as compared to conventional systems that use fasteners or other mechanical means to secure cover sheets to underlying panels. The disclosed vacuum attachment technique utilizes a means for decreasing pressure, such as a pump, that is configured to be connected to at least one port that provides access to a sealed volume between the panel and the cover sheet. In some examples, the means for decreasing pressure is configured to be connected to multiple ports that provide access to multiple corresponding sealed volumes between a multiple panels and multiple cover sheets. In order to create a hermetically-sealed volume between a panel and a cover sheet, a seal can be used to isolate the volume between the panel and the cover sheet. Accordingly, when a cover sheet is disposed on a panel, a sealed volume is created between the panel and the cover sheet. In some examples, the port provides access to a fluid path that extends from the port to the sealed volume between the panel and the cover sheet, the sealed volume being surrounded by the seal. Moreover, when the means for decreasing pressure is connected to the port and is operated to decrease a pressure (e.g., draw a vacuum) within the sealed volume between the panel and the cover sheet, the decrease in the pressure causes the cover sheet to be pressed against the panel by atmospheric pressure. That is, the pressure differential between atmospheric pressure above the cover sheet and the pressure within the sealed volume between the panel and the cover sheet causes a pressing force to be applied to the top of the cover sheet in a direction towards the panel, thereby pressing the cover sheet against (e.g., into contact with) the underlying panel.

[0016] Using a vacuum attachment technique to secure cover sheets to panels creates a sliding resistance (or, a cover sheet friction) that significantly exceeds the sliding resistance achievable using conventional fasteners. This improvement in securing cover sheets to the underlying panels is due to the relatively large area of the cover sheet in combination with the significant downward pressure caused by the above-mentioned pressure differential where atmospheric pressure above the cover sheet presses downward on the cover sheet. In other words, the disclosed vacuum attachment technique creates increased friction against sliding of the cover sheets. This increased cover sheet friction exceeds typical sliding loads applied by vehicles during crash tests by a greater amount than is reasonably achievable using mechanical means, thereby improving the protection of the underlying panels from damage during crash tests. Due to the typical cost of the underlying panels, the techniques, devices, and systems described herein can reduce cost for an operator of a vehicle crash test facility in the long term.

[0017] As mentioned, the techniques, devices, and systems described herein allow for eliminating conventional fasteners that are typically used for securing cover sheets to underlying panels, which results in several downstream benefits. For example, weak spots and stress risers are reduced, if not eliminated, using the techniques, devices, and systems described herein, thereby improving the structural integrity of the panels and the cover sheets. As another example, the production cost of the panels and the cover sheets is reduced due, in part, to the elimination of machining steps for accommodating conventional fasteners. As yet another example, replacement of cover sheets is easier (e.g., less laborious) due to the elimination of steps pertaining to removing and replacing conventional fasteners. As yet another example, leak paths are reduced due to the elimination of holes and other features for accommodating conventional fasteners. As yet another example, visibility (e.g., of the film pit camera(s)) is improved due to the elimination of conventional fasteners, as well as the elimination of machined features in the panels and the cover sheets for accommodating the fasteners or attachment features.

[0018] The techniques, devices, and systems described herein also allow for reducing the thickness of cover sheets that are disposed on the panels of the film pit. This is due, in part, to the downward pressure exerted over the entire surface of the cover sheet enabled by the techniques, devices, and systems described herein, which provides more resistance to buckling and flexure of the cover sheets. Reducing the thickness of the cover sheet can reduce the overall cost of the cover sheet (due to using less material to manufacture the cover sheet).

[0019] As mentioned, when a cover sheet is disposed on a panel, a seal may be used to isolate a volume between the panel and the cover sheet, as described in more detail below. The seal mitigates liquid infiltration between the cover sheet and the panel when a vacuum is drawn by removing air from the sealed volume between the panel and the cover sheet. Thus, the techniques, devices, and systems described herein further mitigate leak paths whereby liquid (e.g., vehicle liquid released during the impact of the vehicle during a crash test) is prevented from being drawn between the panels and the cover sheets by capillary action. This, in turn, improves the visibility (e.g., of the film pit camera(s)) and reduces the frequency and labor involved in performing maintenance on the panels (e.g., to clean and dry the panels), as compared to conventional systems that use fasteners to secure cover sheets to the underlying panels. The techniques, devices, and systems will now be described in detail with reference to figures.

[0020] FIG. 1 illustrates an example system 100 for securing a cover sheet 102 to a panel 104 using a vacuum attachment technique, the panel 104 being configured to be part of a roadway (e.g., a concrete roadway) of a vehicle crash test facility. FIG. 2 depicts an example crash test facility 200 where crash tests are conducted to evaluate or assess the impact safety of vehicles, such as the example vehicle 202 depicted in FIG. 2. Although the example vehicle 202 is depicted as a car, it is to be appreciated that the crash test facility 200 may be used to conduct crash tests of any suitable type of vehicle, such as a truck, an MDB or trolley/cart that carries a portion of a vehicle (e.g., the cab of the vehicle), an airplane, a boat, or any other suitable type of vehicle. During a crash test, the vehicle 202 may be occupied by crash test dummies to evaluate or assess potential injuries a person might sustain in a crash involving the vehicle 202 that is the subject of the crash test.

[0021] With continued reference to FIG. 2, the crash test facility 200 may include a roadway 203. The roadway 203 may be made of concrete or any other suitable material. In some examples, a guidance system may include, without limitation, a guide rail 204 that is part of the roadway 203. The guide rail 204 may be used to guide the vehicle 202 along a path (e.g., a linear path) while the vehicle 202 is pulled up to speed (e.g., up to a threshold velocity) in a direction towards a target 206 (e.g., another vehicle, a pole, a barrier, etc.) until the vehicle 202 impacts (e.g., crashes into) the target 206. The specific parameters (e.g., the velocity of the vehicle 202, the type of target 206, which side of the vehicle 202 is impacted, the angle of impact, etc.) may be dictated by regulation, such as the Federal Motor Vehicle Safety Standards (FMVSS) issued by the National Highway Traffic Safety Administration (NHTSA) in the United States. During a crash test, the crash can be observed. For example, cameras, such as the camera 208 depicted in FIG. 2, can be used to capture images (e.g., video and/or still images) of the vehicle 202 to assess the impact safety of the vehicle 202. The crash test facility 200 may include lights 210 to optimize the quality of the images captured by the cameras.

[0022] The roadway 203 may include one or more recesses for receiving one or more transparent panels 104. In this manner, an individual panel 104 is configured to be part of the roadway 203 for the purpose of photography and/or visual observation of a crash (e.g., from a vantage point underneath the panel (s) 104). In the example crash test facility 200 depicted in FIG. 2, the recess(es) defined in the roadway 203 is a film pit 212. The film pit 212 may contain items, such as one or more additional lights and one or more additional cameras to capture images (e.g., video and/or still images) of the underbody of a vehicle 202 during a crash test. The film pit 212 may be disposed at the impact location(s) where the vehicle 202 impacts the target 206 during a crash test. In some examples, a support framework 400 may be disposed in the film pit 212, as depicted in FIG. 4. The support framework 400 may include one or more support frames 402. The support frames 402 may be horizontally-oriented and configured to receive panels 104 such that the panels 104 lie flat when the panels 104 are placed in the respective support frames 402. The shape of an individual support frame 402 may correspond to the shape of an individual panel 104 that is configured to cover at least a portion of the film pit 212. For example, FIG. 1 depicts a panel 104 that is rectangular in the X-Y plane. This example panel 104 is configured to be supported by a rectangular support frame 402 disposed in the film pit 212, as illustrated in FIG. 4. The example of FIG. 4 shows a support framework 400 that includes nine support frames 402 arranged in a grid. Accordingly, in this example, nine panels 104 are configured to be supported by the nine support frames 402. It is to be appreciated however, that a film pit 212 may be covered by any suitable number of panels 104, such as fewer than nine panels 104 (e.g., a single panel 104), or greater than nine panels 104. Additionally, panels 104 can be of any suitable shape (e.g., in the X-Y plane), such as circular, triangular, square, pentagonal, hexagonal, etc.

[0023] In FIG. 4, the support frames 402 are disposed in the film pit 212 at the top of the film pit 212 and are comprised of horizontally-oriented cross-bars that are orthogonally -positioned with respect to each other in the X-Y plane to create the grid of support frames 402. Accordingly, when panels 104 are placed in the support frames 402 of the support framework 400, the panels 104 cover the top of the film pit 212, leaving room in the film pit 212 for items, such as one or more cameras (not shown in FIG. 4) and one or more lights 210, which may be disposed beneath the panels 104 inside of the film pit 212. FIG. 4 also depicts vertically-oriented posts 404 that support the horizontally-oriented cross-bars of the support frames 402. In the example film pit 212 shown in FIGS. 2-4, part of the support framework 400 also includes a portion of the guide rail 204 that spans the film pit 212. In this manner, the vehicle 202, if guided by the guide rail 204, may travel over the film pit 202 along a prescribed path (e.g., a linear path) during a crash test. Upon placing panels 104 on or in the respective support frames 402 of the support framework 400, cover sheets 102 are placed atop the panels 104. While a support framework 400 including support frames 402 is shown and described herein, it is to be appreciated that such a support framework 400 is optional. For example, a recess(es) defined in the roadway 203 may include a ledge(s) at the top(s) of the recess(es), and the panel (s) 104 can be set in the recess(es) defined in the roadway 203 without a support framework.

[0024] The cover sheets 102 are used as a sacrificial layer to protect the underlying panels 104 from damage during crash testing. Accordingly, FIGS. 2 and 3 depict the cover sheets 102 as the topmost layer that covers the film pit 212. In other words, the panels 104 are disposed underneath the cover sheets 102 in FIGS. 2 and 3, and, hence, the panels 104 are not called out with reference numerals in FIGS. 2 and 3, even though it is to be understood that the panels 104 are disposed underneath the cover sheets 102 in the examples depicted in FIGS. 2 and 3.

[0025] With reference again to FIG. 1, the example system 100 can be used to secure the cover sheet 102 to the panel 104 without using fasteners (e.g., screws, bolts, etc.). For example, in addition to the panel 104 and the cover sheet 102, the example system 100 further includes a seal 106 interposed between the panel 104 and the cover sheet 102, as well as a means for decreasing pressure. The means for decreasing pressure may include a pump 108, such as a vacuum pump, as depicted in FIG. 1. Other examples of a means for decreasing pressure include a blower, a vacuum blower, a vacuum generator, an ejector, a vacuum ejector, a getter, a venturi, a cryopump, an ion pump, a chemical reaction, a temperature change within a volume, a change in volume of a sealed space, or the like. It is to be appreciated that references to “pump” throughout this disclosure may be interchanged with “means for decreasing pressure,” wherein “means for decreasing pressure,” as used herein, can include, but is not limited to, a “pump.” The pump 108 is connected to a port (not shown in FIG. 1) on the panel 104. It is to be appreciated, however, that the port may be disposed on the cover sheet 102 in some examples. FIG. 1 shows an example where the pump 108 is connected to the port via a tube 110. When the system 100 is assembled such that the cover sheet 102 is disposed on the panel 104, and such that the seal 106 is interposed between the panel 104 and the cover sheet 102, the port provides access to a fluid path that extends from the port to a volume between the panel 104 and the cover sheet 102, the volume being surrounded by the seal 106. Accordingly, when the pump 108 is connected to the port and is operated to decrease a pressure (e.g., draw a vacuum) within the volume between the panel 104 and cover sheet 102, the decrease in the pressure within the volume causes the cover sheet 102 to be pressed (e.g., in the negative Z direction) against the panel 104. That is, the pressure differential between atmospheric pressure above the cover sheet 102 and the pressure within the volume between the panel 104 and the cover sheet 102 causes a pressing force to be applied to the top of the cover sheet 102 in a direction (e.g., the negative Z direction) towards the panel 104, thereby pressing the cover sheet 102 into contact with the underlying panel 104 at a force greater than the force of gravity. In some examples, a vacuum reservoir 112 (e.g., a portable air tank) is connected to the pump 108 via a second tube or fittings 114 and is used to eliminate the need to run the pump 108 continuously and/or to allow for small imperfections in the sealing between the panel 104 and the cover sheet 102.

[0026] By securing the cover sheet 102 to the panel 104 without the use of fasteners, visibility of the camera(s) in the film pit 212 is improved. For example, the cover sheet 102 may be devoid, or at least substantially devoid, of holes and/or other features that may otherwise occlude the field of view of the camera(s) disposed in the film pit 212 underneath the panel 104. In some examples, the panel 104 may be devoid, or at least substantially devoid, of holes and/or other features that may otherwise occlude the field of view of the film pit camera(s). In other words, holes and/or other features in the cover sheet 102 and/or the panel 104 are minimized to optimize visibility. That said, a fluid path may be defined in the panel 104 or the cover sheet 102 to provide access to the volume between the panel 104 and the cover sheet 102, yet the fluid path and related features (e.g., the port, openings, etc.) can be positioned at a periphery thereof of the panel 104 and/or the cover sheet 102 to optimize visibility of the film pit camera(s) notwithstanding the existence of the fluid path and related features. Furthermore, as mentioned above, the use of a vacuum to secure the cover sheet 102 to the panel 104 creates a sliding resistance (or, a cover sheet friction) that significantly exceeds the sliding resistance achievable using conventional fasteners, thereby improving the protection of the underlying panel 104 from damage during crash tests.

[0027] The panel 104 and the cover sheet 102 can be made of any suitable material(s) that is transparent. That is, visible light is able to pass through the material of the panel 104 and the material of the cover sheet 102, at least in the Z direction. For example, visible light can enter the top of the cover sheet 102, exit the bottom of the cover sheet 102, enter the top of the panel 104, and exit the bottom of the panel 104, or vice versa (i.e., in the opposite direction). The panel 104 and the cover sheet 102 can be made of the same material or different materials. In some examples, the panel 104 and the cover sheet 102 are both made of an acrylic material. Acrylic is a suitable material for the panel 104 and the cover sheet 102 due to the strength and optical clarity of acrylic. It is to be appreciated, however, that any other suitable transparent material can be used to manufacture the panel 104 and/or the cover sheet 102, such as another polymer (e.g., a polymer other than acrylic), glass, coated glass, doped glass,, or the like.

[0028] In some examples, the panel 104 may have a thickness in the Z direction of about 3 inches to 4 inches. In some examples, the cover sheet 102 may have a thickness in the Z direction of about 0.125 inches to 0.5 inches. In some examples, the cover sheet 102 thickness can be reduced to a thickness that is no greater than about 0.2 inches, no greater than about 0.15 inches, or no greater than about 0.125 inches. Reducing the thickness of the cover sheet without compromising the integrity of the cover sheet 102 with respect to buckling and/or flexure under potential loads applied to the cover sheet 102 during a crash test may allow for reducing the cost of cover sheets and/or improving visibility of the film pit camera(s) beneath the cover sheet 102. The length dimensions (e.g., in the Y direction) and the width dimensions (e.g., in the X direction) of the panel 104 and the cover sheet 102 can vary, depending on the application and the number of panels 104 that are used to cover the top of the film pit 212. As shown in FIG. 2, the length of the panel 104 and the length of the cover sheet 102 in the Y direction may be about half of the length of an average consumer vehicle 102. Similarly, the width of the panel 104 and the width of the cover sheet 102 in the X direction may be about half of the width of an average consumer vehicle 102.

[0029] In some examples, the cover sheets 102 and the panels 104 may be of different sizes (e.g., areas) in the X-Y plane, which allows for covering a single panel 104 with multiple cover sheets 102, and/or for covering multiple panels 104 with a single cover sheet 102. In the former scenario, multiple cover sheets 102 can be disposed on a single panel 104, with multiple corresponding seals 106 interposed between the panel 104 and the cover sheets 102, and with multiple ports that allow for drawing respective vacuums for the respective cover sheets 102 atop the single panel 104. In the latter scenario, a single cover sheet 102 can be disposed on multiple panels 104, with multiple corresponding seals 106 interposed between the panels 104 and the cover sheet 102, and with multiple ports that allow for drawing respective vacuums for the respective panels 104 disposed underneath the single cover sheet 102.

[0030] The pump 108 may represent any suitable type of vacuum pump that is configured to remove gas molecules from a volume to draw a vacuum (e.g., a negative pressure) within the volume. An example of a suitable pump 108 is a 3 cubic feet per minute (CFM) two stage vacuum pump. The pump 108 may include a motor and a compressor for drawing the vacuum(s), as described herein. In some examples, the pump 108 includes an electric motor. In some examples, the pump 108 represents a venturi air-powered vacuum generator. These are merely examples, and other types of pumps are contemplated. The tube 110 that connects the pump 108 to the port (e.g., on the panel 104) may be connected to the inlet of the pump 108.

[0031] In use, the pump 108, the reservoir 112, and/or the tube(s) 110, 114 may be disposed in the film pit 212 underneath the panel 104 and underneath the cover sheet 102. In some examples, an operator may enter the film pit 212 to operate valving and/or to turn on or off vacuum connection to individual panels 104 and/or to “bleed” a vacuum. This may be done to setup the system and/or to replace a cover sheet 102. After setting up the system and/or performing maintenance (e.g., replacing a cover sheet(s) 102), the operator exits the film pit 212 before a crash test commences, for safety reasons. In some examples, a pressure switch 116 is disposed in the film pit 212 and coupled to the pump 108 in order to control the pump 108 automatically, such as to maintain the vacuum(s) within a predetermined pressure range. For example, if the pressure switch 116 detects that the pressure (within the volume between the panel 104 and the cover sheet 102) is not within the predetermined pressure range, the pump 108 may be activated automatically (i.e., without user intervention) to draw a vacuum (e.g., decrease the pressure) until the pressure is within the predetermined pressure range. In some examples, the pressure switch 116 is communicatively coupled to a computing device outside of the film pit 212 (e.g., a computing device in a control room of the crash test facility 200) so that pressure data can be sent to control software executing on the computing device to verily that a vacuum(s) is/are drawn before commencing a crash test.

[0032] FIG. 5 A illustrates a cross-sectional view of a portion of the example system 100 of FIG. 1 taken along section A-A depicted in FIG. 1. In the example of FIG. 5 A, the cover sheet 102 is disposed on the panel 104, and the seal 106 is interposed between the panel 104 and the cover sheet 102 to create a volume 500 between the panel 104 and the cover sheet 102, the volume 500 being surrounded by the seal 106. In other words, the volume 500 may be enclosed by the panel 104 from the bottom, the cover sheet 102 from the top, and the seal 106 from the sides. The seal 106 may allow for creating a hermetic seal to prevent fluid (e.g., air, liquid, etc.) from leaking into or out of the volume 500. It is to be appreciated that FIG. 5A may represent the system 100 in a state prior to a vacuum being drawn. In this state (i.e., prior to drawing a vacuum), although the cover sheet 102 may be pressed against the underlying panel 104 due to the force of gravity, the pressure within the volume 500 may at atmospheric pressure such that the cover sheet 102 is not yet secured to, and brought into intimate contact with, the panel 104 by drawing a vacuum.

[0033] FIG. 5 A shows a port 502 on a bottom 504 of the panel 104. The port 502 provides access to a fluid path 506 defined in the panel 104. The fluid path 506 extends from the port 502 at one end of the fluid path 506 to the volume 500 between the panel 104 and the cover sheet 102 at the other end of the fluid path 506. In the example of FIG. 5A, the fluid path 506 is vertically- oriented in the Z direction and is substantially straight or linear. The fluid path 506 may have a uniform width (e.g., diameter) or a variable width, as is the case in the example of FIG. 5A where the width of the fluid path 506 is wider in a section of the fluid path 506 near the port 502 and thinner in a section of the fluid path 506 near the volume 500.

[0034] The tube 110 is shown as being connected to the port 502 in FIG. 5 A. This allows for connecting the pump 108 to the port 502 because the other end of the tube 110 is connected to the inlet of the pump 108. When the pump 108 is operated, air is removed from the volume 500 between the panel 104 and the cover sheet 102 to decrease the pressure within the volume 500. This is sometimes referred to herein as “drawing a vacuum.” The downward arrow in FIG. 5A indicates the direction of air travel within the fluid path 506 when the pump 108 is operated to draw a vacuum. The pump 108 may be configured to draw a vacuum and thereafter maintain a vacuum so that the cover sheet 102 is secured to the panel 104 during a crash test. In some examples, a series of crash tests can be conducted while the vacuum is maintained, without removing the vacuum between sequential crash tests.

[0035] FIG. 5B illustrates a cross-sectional, exploded view of a portion of the example system 100 of FIG. 1, and FIG. 5C illustrates a cross-sectional view of the portion of the example system 100 with the cover sheet 102 secured to the panel 104 (i.e., after a vacuum is drawn). That is, when a vacuum is drawn, the cover sheet 102 is pressed into intimate contact with the underlying panel 104, and minor surface imperfections allow the vacuum to be drawn throughout the area between the cover sheet 102 and the panel 104 in the X-Y plane. Thus, FIG. 5C shows the state of the system 100 where the volume 500 is since closed by the cover sheet 102 moving downward due to the downward pressure on the cover sheet 102, thereby securing the cover sheet 102 to the panel 104. In some examples, the fluid path 506 is routed to an opening 509 defined in the panel 104 within the recess 514 (e.g., an opening 509 to a volume between the panel 104 and the seal 106). That is, there may be volume between the panel 104 and the seal 106 (e.g., in the upper and lower portions of the recess 514 between the panel 104 and the seal 106) when the vacuum is drawn, as depicted in FIG. 5C. Consequently, when a vacuum is being drawn, air is able to flow around the perimeter of the panel 104 between the panel 104 and the seal 106, and small imperfections and/or debris can then allow the vacuum to propagate inwards along the top 510 of the panel 104. In FIG. 5B, the fluid path 506 is shown as extending from the port 502 to an opening 508 in a top 510 of the panel 104. The opening 508 in the top 510 of the panel 104 opens into the volume 500 shown in FIG. 5A. As shown in FIG. 5B, the port 502, the fluid path 506, and the opening 508 are disposed at a periphery of the panel 104. For example, the port 502, the fluid path 506, and the opening 508 are disposed at a distance, D, from a side 512 of the panel 104. As such, the port 502, the fluid path 506, and the opening 508 are considered to be disposed at the periphery of the panel 104 if D is less than or equal to a threshold distance, such as a threshold distance of about 6 inches. Visibility of the film pit camera(s) is improved by positioning the port 502, the fluid path 506, and the opening 508 at the periphery of the panel 104 such that a remainder of the panel 104 is devoid, or at least substantially devoid, of features that would otherwise occlude the field of view of the film pit camera(s). Furthermore, while an individual panel 104 can include multiple ports 502, fluid paths 506, and openings 508, minimizing the number of ports 502, fluid paths 506, and openings 508 improves the visibility of the film pit camera(s). Accordingly, in some implementations, an individual panel 104 may include a single port 502 providing access to a single fluid path 506, which extends from the port 502 to a single opening 508 that opens into the volume 500.

[0036] FIG. 5B further depicts a recess 514 (sometimes referred to herein as a “gland 514”) defined in the top 510 of the panel 104 along a perimeter of the panel 104. In this example, the seal 106 is configured to be disposed within the recess 514. In some examples, the seal 106 is made of rubber, silicone, or a similar compliant material. In other examples, the seal 106 is a liquid sealant (e.g., a liquid sealant that cures into a solid or semi-solid sealant), a foam sealant (e.g., a foam gasket), a tape sealant, a bead sealant, or any other suitable type of seal material that is impermeable to fluid, such as gas (e.g., air) or liquid (e.g., oil, water, etc.). In some examples, the recess 514 is not defined in the panel 104 and the seal 106 is configured to be pressed against the top 510 of the panel 104, where the top 510 extends all the way to the side 512 of the panel 104 in an implementation without a recess 514. In implementations where the panel 104 includes the recess 514, the port 502 is positioned below the recess 514. In some examples, the recess 514 may be positioned inward from the side 512 (edge) of the panel 104. For example, instead of the “step” depicted in FIG. 5B, a recess 514 in the form of a groove may be defined in the top 510 of the panel 104 with a portion of the top 510 of the panel 104 between the recess 514 and the side 512 of the panel 104.

[0037] FIG. 6A illustrates a cross-sectional, exploded view of a portion of another example system for securing a cover sheet 102 to a panel 104 using a vacuum attachment technique. FIG. 6A depicts a fluid path 606 that extends from a port 602 on the side 512 of the panel 104 to the opening 508 in the top 510 of the panel 104. In this example, the fluid path 606 initially extends from the port 602 in a horizontal direction (e.g., in the X direction) and then the fluid path 606 makes a turn (e.g., a 90 degree elbow), whereafter the fluid path 606 continues to extend in a vertical direction (e.g., in the Z direction) and terminates at the opening 508 in the top 510 of the panel 104. In implementations where the panel 104 includes the recess 514, the port 602 is also positioned below the recess 514. For example, the port 602 is positioned between the bottom 504 of the panel 104 and the recess 514. In the example of FIG. 6A, the fluid path 606 and the opening 508 are disposed at a periphery of the panel 104. For example, the fluid path 606 and the opening 508 may be disposed at a distance, D, from the side 512 of the panel 104, where the fluid path 606 and the opening 508 are considered to be disposed at the periphery of the panel 104 if D is less than or equal to a threshold distance, such as a threshold distance of about 6 inches. As mentioned above, this improves visibility of the film pit camera(s). [0038] FIG. 6B illustrates a cross-sectional, exploded view of a portion of another example system for securing a cover sheet 102 to a panel 104 using a vacuum attachment technique. FIG. 6B depicts a fluid path 612 that extends from a port 608 on a top 616 of the cover sheet 102 to an opening 614 in a bottom 610 of the cover sheet 102. Accordingly, when the cover sheet 102 is secured to the panel 104, the fluid path 612 extends from the port 608 to the volume between the panel 104 and the cover sheet 102. In the example of FIG. 6B, the fluid path 612 is vertically-oriented in the Z direction and is substantially straight or linear. In the example of FIG. 6B, the port 608, the fluid path 612, and the opening 614 are disposed at a periphery of the cover sheet 102. For example, the port 608, the fluid path 612, and the opening 614 may be disposed at a distance, D, from the side 618 of the cover sheet 102, where the port 608, the fluid path 612, and the opening 614 are considered to be disposed at the periphery of the cover sheet 102 if D is less than or equal to a threshold distance, such as a threshold distance of about 6 inches. As mentioned above, this improves visibility of the film pit camera(s).

[0039] Although the seal 106 is described above as being interposed between the panel 104 and the cover sheet 102 when the system 100 is assembled, it is to be appreciated that other types of seals and/or seal configurations are possible and are contemplated herein. For example, the seal 106 can be disposed outside of a perimeter of the panel 104 and/or outside of a perimeter of the cover sheet 102. For example, if the cover sheet 102 is disposed on the panel 104, the seal 106 may be disposed on a small gap or seam at the interface between the panel 104 and the cover sheet 102, thereby isolating a volume 500 between the panel 104 and the cover sheet 102. Accordingly, the seal 106 is configured to isolate the volume 500 between the panel 104 and the cover sheet 102 in a variety of ways, as described herein.

[0040] Moreover, the port may be disposed on the seal 106, in some examples, instead of, or in addition to, the port(s) 502, 602, 608 shown as being disposed on the panel 104 and/or the cover sheet 102. Accordingly, it is to be appreciated that a port of the system 100 can provide access to the sealed volume 500 between the panel 104 and the cover sheet 102 in a variety of ways, such as by disposing the port 502, 602 on the panel 104, by disposing the port 608 on the cover sheet 102, and/or by disposing the port on the seal 106 itself. In any of these configurations, a fluid path is configured to communicate pressure from the sealed volume 500 to the port, such as a fluid path defined in the panel 104, and/or a fluid path defined in the cover sheet 102, and/or a fluid path defined in the seal 106 itself.

[0041] FIG. 7 illustrates an example system 700 including multiple cover sheets 102 secured to multiple panels 104 via a pump 108 that is configured to be connected to respective ports 502 for selectively drawing and/or removing vacuum associated with individual ones of the multiple panels 104. For example, FIG. 7 illustrates a first panel 104(1), a first cover sheet 102(1) secured to the first panel 104(1), and a first seal 106(1) interposed between the first panel 104(1) and the first cover sheet 102(1). In addition, a first port 502(1) on the bottom of the first panel 104(1) provides access to a first fluid path 506(1) that extends from the first port 502(1) to a first volume 500(1) between the first panel 104(1) and the first cover sheet 102(1), the first volume 500(1) being surrounded by the first seal 106(1). FIG. 7 further illustrates a second panel 104(2), a second cover sheet 102(2) secured to the second panel 104(2), and a second seal 106(2) interposed between the second panel 104(2) and the second cover sheet 102(2). In addition, a second port 502(2) on the bottom of the second panel 104(2) provides access to a second fluid path 506(2) that extends from the second port 502(2) to a second volume 500(2) between the second panel 104(2) and the second cover sheet 102(2), the second volume 500(2) being surrounded by the second seal 106(2). It is to be appreciated that the ports 502 and fluid paths 506 may be configured differently than the configuration shown in FIG. 7, such as the configuration shown in FIG. 6A. Furthermore, although two panels 104(1) and 104(2) are shown, the system 700 may include any number of panels 104, such as more than two panels 104, as indicated by the ellipsis in FIG. 7. For example, the system 700 may include nine panels 104 that are to be placed within nine corresponding support frames 402, as depicted in FIG. 4. Additionally, the system 700 may include various arrangements of panels 104 and cover sheets 102, such as a one-to-one panel 104-to-cover sheet 102 arrangement, a one-to-many panel 104-to-cover sheets 102 arrangement, or a many-to-one panels 104-to-cover sheet 102 arrangement, as mentioned above.

[0042] In the system 700, the pump 108 is connected to the respective ports 502(1), 502(2), etc. via the tube 110. For example, a first end of the tube 110 may be connected to an inlet of the pump 108, and a second end of the tube 110 may be connected to a splitter 702, which may connect the single tube 110 to a plurality of additional tubes 704(1), 704(2), etc. For example, a first tube 704(1) may include a first end connected to the first port 502(1) and a second end connected the splitter 702, a second tube 704(2) may include a first end connected to the second port 502(2) and a second end connected the splitter 702, and so on and so forth for any suitable number of tubes 704. In some examples, one or more check valves (or, one-way valves, unidirectional valves, etc.) may be used to prevent an air leak from affecting a vacuum(s) drawn between a panel (s) 104 and a cover sheet(s) 102. For example, the splitter 702 can include one or more check valves to prevent an air leak in a particular tube 704 from affecting the vacuum(s) drawn using the remaining tube(s) 704 of the system 700. In some examples, check valves are included closer to the panels 104 themselves, such as check valves in the ports 502, to maintain vacuum in the event of an air leak in a tube(s) 704 and/or an air leak in the tube 110.

[0043] In the system 700, the pump 108 can be operated to simultaneously draw respective vacuums between the panels 104 and the cover sheets 102 by removing air from the respective volumes 500(1), 500(2), etc. in parallel until the respective pressures within the respective volumes 500(1), 500(2), etc. are decreased to a threshold pressure that is suitable for securing the cover sheets 102 to the panels 104 during a crash test. In some examples, valving connected to the pump 108 can be operated to sequentially draw respective vacuums between the panels 104 and the cover sheets 102 by removing air from the respective volumes 500(1), 500(2), etc. one after the other. Once the vacuums are drawn, the system 700 may allow for selectively removing vacuum on an individual panel basis by isolating the vacuum associated with each panel 104. For example, a first vacuum that was drawn by removing air from the first volume 500(1) can be removed (e.g., by venting to increase the pressure within the first volume 500(1) to atmospheric pressure) without removing a second vacuum that was drawn by removing air from the second volume 500(2). In some examples, the vacuum associated with each panel 104 is isolated using ball valves (e.g., multiple ball valves for each panel 104 and corresponding cover sheet 102) or a similar component. In other words, the system 700 may be configured to maintain the vacuums that are already drawn for a subset of the panels 104 while removing vacuum with respect to one or more of the panels 104. This allows personnel to perform maintenance on an individual panel 104 without having to remove the vacuum that is already drawn for the remaining panels 104. Because the number of fluid paths 506 may be minimized to optimize visibility of the film pit camera(s), it may take a significant amount of time to draw the respective vacuums for the plurality of panels 104. Accordingly, the ability to selectively remove vacuum for an individual panel 104 without having to remove the respective vacuums for the remaining panels 104 of the system 700 can significantly reduce the amount of time spent performing maintenance on an individual panel 104 and readying the system 700 for another crash test after maintenance on the panel 104 is completed.

[0044] In some examples, the system 700 and/or components thereof (e.g., the pump 108, the splitter 702, etc.) may be controlled manually (e.g., by an operator) in order to selectively draw and/or remove vacuum for an individual panel 104 or multiple panels 104. For example, an operator may manipulate a control (s) (e.g., a knob, a lever, a switch, etc.) on the splitter 702 and/or a control(s) on the port 502 to remove vacuum with respect to an individual panel 104. In some examples, the system 700 and/or components thereof (e.g., the pump 108, the splitter 702, etc.) may be automatically controlled using a pressure switch 116 (relay) set to a predetermined pressure range so that the pump 108 is activated to maintain the pressure within the predetermined pressure range. In some examples, the system 700 and/or components thereof (e.g., the pump 108, the splitter 702, etc.) may be controlled based on an operator providing user input to a computing device. For example, an operator may control the operation of the system 700 and/or components thereof (e.g., the pump 108, the splitter 702, etc.) remotely from a control room. In some examples, the splitter 702 may be disposed in a separate pit adjacent to the film pit 212 and controlled by a computing device above ground in the crash test facility 200. [0045] The processes described herein are illustrated as collections of blocks in logical flow diagrams, which represent a sequence of operations. The order in which the blocks are described should not be construed as a limitation, unless specifically noted. Any number of the described blocks may be combined in any order and/or in parallel to implement the process, or alternative processes, and not all of the blocks need be executed. For discussion purposes, the processes are described with reference to the environments, architectures and systems described in the examples herein, although the processes may be implemented in a wide variety of other environments, architectures and systems.

[0046] FIG. 8 depicts an example process 800 for securing a cover sheet(s) 102 to a panel(s) 104 using a vacuum attachment technique, the panel(s) 104 being configured to cover at least a portion of a film pit 212 of a vehicle crash test facility 200. For discussion purposes, the process 800 is described with reference to the previous figures.

[0047] At 802, a panel 104 is set in a portion of a roadway 203 of a vehicle crash test facility 200 for the purpose of photography or visual observation of a crash. In some examples, setting the panel 104 in the portion of the roadway 203 at block 802 includes placing the panel 104 on a support frame 402 disposed in a film pit 212 of a vehicle crash test facility 200, the roadway 203 including the film pit 212. For example, personnel within the crash test facility 200 may transport the panel 104 from a storage location within, or external to, the crash test facility 200 to the film pit 212, and the personnel may lay the panel 104 into a recess(es) defined in the roadway 203 (e.g., by laying the panel 104 into the support frame 402). In some examples, block 802 is performed by human personnel. In some examples, machines and/or apparatuses (e.g., forklifts, pulley systems, etc.) are at least partially utilized at block 802 for aiding in the placement of the panel 104 (e.g., within the support frame 402). The panel(s) 104 is transparent (e.g., made of acrylic) to allow one or more cameras in the film pit 212 to capture images of vehicles 202 above the film pit 212 while the film pit 212 is at least partially covered with the panel 104. It is to be appreciated that the panel 104 may be installed at 802 and seldom removed due to the protection provided by the cover sheet 102, as described herein.

[0048] At 804, a cover sheet 102 is placed atop the panel 104. For example, personnel within the crash test facility 200 may transport the cover sheet 102 from a storage location within, or external to, the crash test facility 200 to the film pit 212, and the personnel may lay the cover sheet 102 atop the panel 104 that is supported by the support frame 402. In some examples, block 804 is performed by human personnel. In some examples, machines and/or apparatuses (e.g., forklifts, pulley systems, etc.) are at least partially utilized at block 804 for aiding in the placement of the cover sheet 102 atop the panel 104. The cover sheet 102 is transparent (e.g., made of acrylic) to allow the camera(s) in the film pit 212 to capture images of vehicles 202 above the film pit 212 while the film pit 212 is at least partially covered with the panel 104 and the cover sheet 102.

[0049] At 806, a volume 500 between the panel 104 and the cover sheet 102 is sealed to create a sealed volume 500. For example, a seal 106 may be interposed between the panel 104 and the cover sheet 102. As mentioned above, the seal 106 may be disposed outside of a perimeter of the panel 104 and/or outside of a perimeter of the cover sheet 102, in some examples. It is to be appreciated that, in the examples described herein, the positioning of the seal 106 between the panel 104 and the cover sheet 102 is performed prior to the placement of the cover sheet 102 atop the panel 104 at block 804. For example, a ring-shaped seal 106 made of a compliant material (e.g., rubber, silicone, etc.) may be placed atop the panel 104, and the cover sheet 102 may be placed atop the seal 106 to sandwich the seal 106 between the panel 104 and the cover sheet 102. In some examples, the panel 104 has a recess 514 defined in the top 510 of the panel 104 along a perimeter of the panel 104, and the seal 106 is placed within the recess 514 prior to placing the cover sheet 102 atop the panel 104. In some examples, personnel may stretch the compliant seal 106 around the top 510 of the panel 104 to position the seal 106 within the recess 514. The seal 106 can remain on the panel 104 when replacing the cover sheet 102, in some examples.

[0050] At 808, a pump 108 is connected to a port 502, 602, 608. The port 502, 602 may be on the panel 104. Additionally, or alternatively, the port 608 may be on the cover sheet 102, and/or on the seal 106 itself. Examples of these port configurations are shown in FIGS. 5A to 6B. The port 502, 602, 608 provides access to a fluid path 506, 606, 612 that extends from the port 502, 602, 608 to the volume 500 between the panel 104 and the cover sheet 102, the volume 500 being surrounded by the seal 106.

[0051] At 810, if additional panels 104 are to cover the film pit 212, the process 800 follows the YES route from block 810 to iterate blocks 802 to 808 so as to cover the film pit 212 with one or more additional panels 104 and to connect the pump 108 to the additional port(s) 502, 602. Once the panel(s) 104 have been placed in the support frames 402 of the support framework 400 to cover the film pit 212, and once the pump 108 has been connected to the port(s) associated with the panel(s) 104, the process 800 follows the NO route from block 810 to block 812.

[0052] At 812, the pump 108 is operated to decrease a pressure(s) within the volume(s) 500 between the panel(s) 104 and the cover sheet(s) 102. A decrease in the pressure(s) within the volume(s) 500 between the panel(s) 104 and the cover sheet(s) 102 causes the cover sheet(s) 102 to be pressed against the panel(s) 104, thereby securing the cover sheet(s) 102 to the panel (s) 104 without the use of conventional fasteners (e.g., screws, bolts, etc.). As mentioned above, this allows for minimizing the visible features (e.g., holes, hardware, etc.) that would otherwise occlude the field of view of the film pit camera(s), thereby improving visibility of the vehicle above the film pit 212 to capture images with little-to-no occlusions. The vacuum attachment technique described in the process 800 also increases the cover sheet friction, as compared to using mechanical means, which better secures the cover sheet(s) 102 to the panel(s) 104 to mitigate damage to the underlying panel(s) 104 during crash testing. In some examples, the pump 108 is operated manually by a human operator at block 812. In some examples, a power switch external to the film pit 212 may allow for personnel to remain above ground, without the personnel having to enter the film pit 212 in order to draw a vacuum(s) to secure the cover sheet(s) 102 to the panel(s) 104. After the cover sheet(s) 102 is/are initially secured to the panel(s) 104, the system 100, 700 may self-operate (e.g., automatically, without human intervention) via the reservoir 112 and a pressure switch 116 set to a predetermined pressure range so that the pump 108 is activated, as needed, to maintain the pressure within the predetermined pressure range.

[0053] If multiple panels 104 are used to cover the film pit 212, blocks 814 and 816 may be performed as part of the process 800, in some examples. At 814, for example, the pump 108 may be operated to remove air from the respective volumes 500(1), 500(2), etc. between multiple panels 104 and multiple corresponding cover sheets 102 until the respective pressures within the respective volumes 500(1), 500(2), etc. are decreased to a threshold pressure suitable for securing the cover sheets 102 to the panels 104. In an example, at block 814, the pump 108 may draw a first vacuum by removing air from a first volume 500(1) between a first panel 104(1) and a first cover sheet 102(1) until a first pressure within the first volume 500(2) is decreased to a threshold pressure, draw a second vacuum by removing air from the second volume 500(2) between a second panel 104(2) and a second cover sheet 102(2) until a second pressure within the second volume 500(2) is decreased to the threshold pressure, and so on and so forth for any suitable number of panels 104 that may be utilized to cover the film pit 212. It is to be appreciated that the respective vacuums may be drawn at block 814 simultaneously (e.g., in parallel), sequentially, or a combination thereof (e.g., in batches).

[0054] At 816, a vacuum(s) may be selectively removed with respect to an individual panel(s) 104 after having drawn the respective vacuums for the multiple panels 104 at block 814. For example, after drawing the first vacuum (associated with the first volume 500(1)) and after drawing the second vacuum (associated with eh second volume 500(2)), the first vacuum can be removed to increase the first pressure to atmospheric pressure without removing the second vacuum, or vice versa. In some examples, selective removal of a vacuum(s) may occur at block 816 based on a human operator manually operating a control(s) of the system 700 and/or a component thereof, such as the pump 108, the splitter 702, and/or a port 704. In some examples, the splitter 702 includes valving and/or similar components (e.g., ball valves) that are used for removing vacuum for an individual panel 104 by venting to atmospheric pressure. The selective removal of vacuum(s) at block 816 may allow for personnel to perform maintenance on an individual panel(s) 104 without removing vacuum from the remainder of the panels 104 covering the film pit 212. Because the number of fluid paths 506 may be minimized to optimize visibility of the film pit camera(s), it may take a significant amount of time to draw the respective vacuums for the plurality of panels 104. Accordingly, the ability to selectively remove vacuum for an individual panel (s) 104 without having to remove the respective vacuums for the remaining panels 104 of the system 700 can significantly reduce the amount of time spent performing maintenance on an individual panel 104 and readying the system 700 for another crash test after maintenance on the panel 104 is completed.

[0055] Unless otherwise indicated, all numbers expressing quantities, properties, conditions, and so forth used in the specification and claims are to be understood as being modified in all instances by the term “about.” Accordingly, unless indicated to the contrary, the numerical parameters set forth in the specification and attached claims are approximations that may vary depending upon the desired properties sought to be obtained by the present disclosure. At the very least, and not as an attempt to limit the application of the doctrine of equivalents to the scope of the claims, each numerical parameter should at least be construed in light of the number of reported significant digits and by applying ordinary rounding techniques. When further clarity is required, the term “about” has the meaning reasonably ascribed to it by a person skilled in the art when used in conjunction with a stated numerical value or range, i.e. denoting somewhat more or somewhat less than the stated value or range, to within a range of ±20% of the stated value; ±19% of the stated value; ±18% of the stated value; ±17% of the stated value; ±16% of the stated value; ±15% of the stated value; ±14% of the stated value; ±13% of the stated value; ±12% of the stated value; ±11% of the stated value; ±10% of the stated value; ±9% of the stated value; ±8% of the stated value; ±7% of the stated value; ±6% of the stated value; ±5% of the stated value; ±4% of the stated value; ±3% of the stated value; ±2% of the stated value; or ±1% of the stated value.

[0056] While the foregoing invention is described with respect to the specific examples, it is to be understood that the scope of the invention is not limited to these specific examples. Since other modifications and changes varied to fit particular operating requirements and environments will be apparent to those skilled in the art, the invention is not considered limited to the example chosen for purposes of disclosure, and covers all changes and modifications which do not constitute departures from the true spirit and scope of this invention.

[0057] Although the application describes embodiments having specific structural features and/or methodological acts, it is to be understood that the claims are not necessarily limited to the specific features or acts described. Rather, the specific features and acts are merely illustrative some embodiments that fall within the scope of the claims of the application.