Tunnel surrounding rock large deformation high-precision monitoring equipment based on laser interferometryTechnical Field
The invention belongs to the technical field of laser detection deformation, and particularly relates to a high-precision monitoring device for large deformation of tunnel surrounding rock based on laser interferometry.
Background
Along with the rapid promotion of infrastructure construction in China, tunnel engineering is widely applied in the fields of traffic, water conservancy and the like. In the tunnel construction and operation process, surrounding rock large deformation is one of important factors threatening tunnel safety, and the surrounding rock large deformation not only can cause tunnel structure damage and influence normal use, but also can cause serious accidents such as collapse and the like, thereby causing huge economic loss and casualties. Therefore, the high-precision, real-time and omnibearing monitoring of the large deformation of the surrounding rock of the tunnel is very important.
At present, the laser interferometer is applied to the field of monitoring the large deformation of the surrounding rock of the tunnel to a certain extent by virtue of the high-precision measurement characteristic. However, existing monitoring methods have a number of limitations. On the one hand, the traditional laser interferometer mounting mode is relatively fixed, flexible detection at multiple angles is difficult to achieve, surrounding rock deformation data at different positions and in different directions of a tunnel cannot be comprehensively obtained, a blind area exists in monitoring, and accurate evaluation of the whole deformation state of the surrounding rock is affected. On the other hand, in order to solve the angle adjustment problem, part of equipment adopts the auxiliary adjustment of the angle of the laser interferometer of carousel, but current carousel structure is in long-time use, owing to lack effectual spacing and stable mechanism, takes place to rock easily, and then influences the measurement accuracy of laser interferometer for monitoring data appears the deviation, can't provide reliable foundation for tunnel safety evaluation. Therefore, development of a tunnel surrounding rock large deformation monitoring device based on laser interferometry, which can realize multi-angle high-precision detection and has good stability, is needed.
Disclosure of Invention
Aiming at the problems in the prior art, the invention provides the tunnel surrounding rock large deformation high-precision monitoring equipment based on laser interferometry, which has the advantages of being capable of realizing multi-angle high-precision detection and good in stability, and solves the problems in the prior art.
The invention discloses tunnel surrounding rock large-deformation high-precision monitoring equipment based on laser interferometry, which comprises a laser interferometer and a base, wherein the laser interferometer is connected with the monitor through signals, a round hole is formed in the middle of the base, a fixed disc aligned with the round hole is fixedly connected to the lower surface of the base, a limiting ring is fixedly clamped on the inner surface of the side wall of the fixed disc, a first rotating shaft is rotatably connected to the bottom of the fixed disc, a driving piece is fixedly connected to the lower half section of the first rotating shaft, a rotating ring is fixedly connected to the upper half section of the first rotating shaft, the rotating ring is positioned in the limiting ring and is attached to the limiting ring, the rotating ring extends into the round hole, a U-shaped frame is fixedly connected to the upper side of the rotating ring, the lower surface of the U-shaped frame is attached to the upper surface of the base, a rotating disc is rotatably connected to the middle upper part of the U-shaped frame, and the laser interferometer is fixedly connected to the upper surface of the rotating disc. The bottom upper surface of U type frame is equipped with the elastic expansion link, elastic expansion link upper end fixedly connected with protection casing, the protection casing laminating in the carousel. When the laser interferometer is used, the protective cover is pressed downwards by the turntable in the process that the turntable rotates 180 degrees upwards from the front surface until the front surface of the turntable is downward, and the protective cover can cover the laser interferometer at the moment so as to protect.
As preferable in the invention, the center of the turntable is fixedly connected with a mounting hole, the bottom of the laser interferometer is fixedly connected with a bolt, and the bolt penetrates through the mounting hole and is connected with the mounting hole through a nut.
The elastic telescopic rod comprises a lower pipe body, a spring and an upper pipe body, wherein the lower end of the lower pipe body is fixedly connected to the upper surface of the bottom of the U-shaped frame, the upper pipe body is inserted into the lower pipe body in a sliding mode, a connecting seat is fixedly connected to the outer side of the lower pipe body, a thread groove is formed in the outer surface of the connecting seat, the lower end of the spring is connected to the thread groove, and the upper end of the spring is connected to the lower surface of the protective cover in a rotating mode.
As the preferable mode of the invention, the upper end of the upper pipe body is communicated with the protective cover, a cylindrical air bag is arranged in the upper pipe body, the upper end of the cylindrical air bag extends into the protective cover, one side of the cylindrical air bag is attached to the inner wall of the upper pipe body, a strip-shaped groove is formed in the cylindrical air bag, a vertical rod is fixedly connected in the lower pipe body, a pressing rod is fixedly connected to the upper end of the vertical rod, and the pressing rod is positioned in the strip-shaped groove.
Preferably, the upper edge of the protective cover is fixedly connected with a strip-shaped air bag, and the strip-shaped air bag is communicated with the cylindrical air bag through a hose.
As preferable in the invention, the upper end of the cylindrical air bag is fixedly connected with a hairbrush.
The driving piece comprises a turbine, a worm and a first motor, wherein the turbine is fixedly connected with the first rotating shaft, the worm is connected with the turbine, the worm is fixedly connected with the lower surface of the base through a bearing seat, and one end of the worm is fixedly connected with the output end of the first motor.
As preferable, the side part of the U-shaped frame is fixedly connected with a second motor, the output end of the second motor is fixedly connected with a second rotating shaft, the second rotating shaft is rotatably connected with the U-shaped frame, and the rotary table is fixedly connected with the middle part of the second rotating shaft.
The invention preferably further comprises a support frame, wherein the support frame is provided with support legs, a sliding rail is fixed on the support frame, a sliding block is fixedly connected to the lower side of the base, the sliding block is connected to the sliding rail in a sliding mode, a threaded sleeve is fixedly connected to the lower surface of the base, a third motor is fixedly connected to the support frame, a screw rod is fixedly connected to an output shaft of the third motor, and the screw rod is connected to the threaded sleeve in a threaded mode.
Compared with the prior art, the invention has the following beneficial effects:
the device realizes stable horizontal rotation of the U-shaped frame through matching of the swivel and the limiting ring, and the second motor drives the turntable to realize vertical angle adjustment of the laser interferometer, so that comprehensive monitoring can be carried out on tunnel surrounding rock from multiple angles and multiple directions. Compared with the traditional monitoring equipment, the monitoring blind area is effectively eliminated, more complete and accurate surrounding rock deformation data can be obtained, rich and reliable data support is provided for safety evaluation of tunnel engineering, and the monitoring precision and comprehensiveness are improved. And because the elastic telescopic rod supports the turntable through the protective cover, the vibration of the laser interferometer can be reduced, and the accuracy is improved.
The rotating ring is limited by the limiting ring, the lower surface of the U-shaped frame is attached to the base, the displacement and the inclination of the U-shaped frame in the rotating process are limited, and the stability of the U-shaped frame and the laser interferometer arranged on the U-shaped frame in the long-time use process is ensured. Meanwhile, the connection structure of the second motor and the rotary table is also optimally designed, so that stable operation in the angle adjusting process is ensured, the influence on measurement accuracy caused by equipment shaking is reduced, monitoring data are more real and reliable, the service life of equipment is prolonged, and the equipment maintenance cost is reduced.
The angle adjustment operation of the device is simple and easy to understand, and the angle adjustment of the laser interferometer in the horizontal and vertical directions can be realized by controlling the U-shaped frame and the turntable. No matter in the equipment installation and debugging stage or in the later daily monitoring process, operators can quickly and conveniently adjust the monitoring angle, so that the working efficiency is improved, the operation difficulty is reduced, and the smooth development of the monitoring work is facilitated.
The device is widely applicable to tunnel engineering with different types and different geological conditions, whether the tunnel is a mountain tunnel, a water bottom tunnel or an urban underground tunnel, and can realize high-precision monitoring of large deformation of surrounding rocks of the tunnel by flexibly adjusting the angle of the laser interferometer. The adaptability of the system can meet diversified engineering requirements, and guarantees are provided for the safe construction and operation of various tunnel engineering.
Drawings
Fig. 1 is a schematic structural diagram of a first view angle of a tunnel surrounding rock large deformation high-precision monitoring device based on laser interferometry according to embodiment 1 of the present invention;
FIG. 2 is an enlarged schematic view of the portion A in FIG. 1 according to embodiment 1 of the present invention;
fig. 3 is a schematic diagram of a front view structure provided in embodiment 1 of the present invention;
FIG. 4 is a schematic cross-sectional view of the structure at B-B in FIG. 3 provided in example 1 of the present invention;
FIG. 5 is an enlarged schematic view of the portion D of FIG. 4 according to embodiment 1 of the present invention;
FIG. 6 is an enlarged schematic view of the portion C in FIG. 4 according to embodiment 1 of the present invention;
fig. 7 is a schematic structural diagram of a second view angle of a tunnel surrounding rock large deformation high-precision monitoring device based on laser interferometry according to embodiment 1 of the present invention;
FIG. 8 is an enlarged schematic view of the portion E in FIG. 7 according to embodiment 1 of the present invention;
Fig. 9 is a schematic cross-sectional structure diagram of a device for monitoring large deformation of tunnel surrounding rock with high precision based on laser interferometry according to embodiment 2 of the present invention;
Fig. 10 is an enlarged schematic view of the part F in fig. 9 provided in embodiment 2 of the present invention, in which the upper half of the upright 17 is blocked by the pillar-shaped air bag 15;
FIG. 11 is a schematic view of the structure of the columnar airbag, the bar-shaped groove, the upright and the compression bar provided in embodiment 2 of the present invention, wherein the orientations of the columnar airbag, the bar-shaped groove, the upright and the compression bar are opposite to those in FIG. 10, and the upper half part of the upright 17 is not blocked by the columnar airbag 15;
Fig. 12 is an enlarged schematic view of the portion G in fig. 9 provided in embodiment 2 of the present invention;
fig. 13 is a schematic cross-sectional structural diagram of a device for monitoring large deformation of tunnel surrounding rock with high precision based on laser interferometry according to embodiment 3 of the present invention;
Fig. 14 is an exploded view of the tunnel surrounding rock large deformation high-precision monitoring device based on laser interferometry, mainly for displaying the orientation of the round hole 2.
1, A base, 2, a round hole, 3, a fixed disc, 4, a limiting ring, 5, a first rotating shaft, 6, a driving piece, 61, a turbine, 62, a worm, 63, a first motor, 7, a rotating ring, 8, a U-shaped frame, 9, a rotating disc, 10, a laser interferometer, 12, a bolt, 13, an elastic telescopic rod, 131, a lower tube body, 132, a spring, 133, an upper tube body, 134, a connecting seat, 135, a thread groove, 14, a protective cover, 15, a cylindrical air bag, 16, a strip groove, 17, a vertical rod, 18, a compression rod, 19, a strip air bag, 20, a second motor, 21, a second rotating shaft, 22, a supporting frame, 23, a supporting foot, 24, a sliding rail, 25, a sliding block, 26, a screw sleeve, 27, a third motor, 28, a screw rod, 29, a threaded hole and 30, and a stud.
Detailed Description
For a further understanding of the invention, its features and advantages, reference is now made to the following examples, which are illustrated in the accompanying drawings.
The structure of the present invention will be described in detail with reference to the accompanying drawings.
Example 1
As shown in fig. 1 to 8 and 14, the tunnel surrounding rock large deformation high-precision monitoring device based on laser interferometry provided by the embodiment of the invention comprises a laser interferometer 10 and a base 1, wherein the laser interferometer 10 is in signal connection with the monitor, a round hole 2 (see fig. 6) is arranged in the middle of the base 1, a fixed disc 3 (see fig. 6-8) aligned with the round hole 2 is fixedly connected to the lower surface of the base 1, a limiting ring 4 (see fig. 6-8) is fixedly clamped to the inner surface of the side wall of the fixed disc 3, a first rotating shaft 5 is rotatably connected to the bottom of the fixed disc 3, a driving piece 6 is fixedly connected to the lower half section of the first rotating shaft 5, a rotating ring 7 is fixedly connected to the upper half section of the first rotating shaft 5, the rotating ring 7 is positioned in the inside the limiting ring 4 and is attached to the limiting ring 4, the rotating ring 7 extends into the round hole 2, a U-shaped frame 8 is fixedly connected to the upper side of the rotating ring 7, the lower surface of the U-shaped frame 8 is attached to the upper surface of the base 1, and the upper rotating disc 9 is fixedly connected to the upper rotating disc 10.
The device monitors the large deformation of the tunnel surrounding rock with high precision by stably adjusting the angles of the laser interferometer 10 at multiple angles, and specifically comprises the following steps that when the angle adjustment of the laser interferometer 10 in the horizontal direction is required, the driving piece 6 drives the first rotating shaft 5 to rotate, and the first rotating shaft 5 drives the rotating ring 7 to stably rotate at 360 degrees under the limiting action of the limiting ring 4. Because swivel 7 is spacing by spacing ring 4, and with swivel 7 fixed connection's U type frame 8 lower surface laminating in base 1 upper surface, this structural design has effectively restricted U type frame 8 and has rocked and slope in the rotation in-process, has guaranteed U type frame 8 pivoted stability. When the U-shaped frame 8 rotates, the turntable 9 and the laser interferometer 10 fixed on the U-shaped frame rotate along with the turntable, so that the angle adjustment of the laser interferometer 10 in the horizontal direction is realized, and surrounding rocks in different directions of a tunnel can be monitored.
In the aspect of angle adjustment in the vertical direction, the turntable 9 rotates, so that the angle of the laser interferometer 10 on the upper side of the turntable 9 can be further adjusted, the angle change of the laser interferometer 10 in the vertical direction is realized, and surrounding rocks at different height positions such as the top and the side wall of a tunnel can be measured.
Throughout the monitoring process, the laser interferometer 10 measures precisely the small displacement changes of the tunnel surrounding rock surface by emitting a laser beam, using the principle of laser interference. When the surrounding rock is deformed, the optical path of the reflected laser beam is changed, and the laser interferometer 10 converts the change of the optical path difference into specific displacement data by analyzing the change of the optical path difference, so that high-precision monitoring of the large deformation of the surrounding rock of the tunnel is realized.
Further, an elastic telescopic rod 13 is arranged on the upper surface of the bottom of the U-shaped frame 8, a protective cover 14 is fixedly connected to the upper end of the elastic telescopic rod 13, and the protective cover 14 is attached to the turntable 9. When the laser interferometer 10 is used, in the process that the turntable 9 rotates 180 degrees from the front side to the upper position, the turntable 9 presses the protective cover 14 downwards until the front side of the turntable 9 is downwards, and the protective cover 14 can cover the laser interferometer 10 at the moment so as to protect. And because the elastic telescopic rod 13 supports the turntable 9 through the protective cover 14, the vibration of the laser interferometer 10 can be reduced, and the accuracy is improved. Preferably, the turntable 9 further comprises an inclination sensor, which is signally connected to the laser interferometer 10. It is determined whether in a horizontal (front up) or inverted (front down) state. When the tilt sensor detects that the front of the turntable 9 is down, the laser interferometer 10 is automatically turned off. Otherwise, the laser interferometer 10 is automatically turned on.
Further, a mounting hole is fixedly connected to the center of the turntable 9, a bolt 12 is fixedly connected to the bottom of the laser interferometer 10, and the bolt 12 penetrates through the mounting hole and is connected through a nut. The mounting hole in the center of the turntable 9 is used for penetrating through a bolt 12 at the bottom of the laser interferometer 10, and then the bolt 12 is fixed through a nut, so that the laser interferometer 10 is connected with the turntable 9. This connection makes use of the fastening characteristics of the screw thread so that the laser interferometer 10 can be stably mounted on the turntable 9, and when disassembly is required, the laser interferometer 10 can be easily removed by simply unscrewing the nut.
Specifically, the elastic telescopic rod 13 comprises a lower pipe body 131, a spring 132 and an upper pipe body 133, wherein the lower end of the lower pipe body 131 is fixedly connected to the upper surface of the bottom of the U-shaped frame 8, the upper pipe body 133 is slidably inserted into the lower pipe body 131, a connecting seat 134 is fixedly connected to the outer side of the lower pipe body 131, a thread groove 135 is formed in the outer surface of the connecting seat 134, the lower end of the spring 132 is connected to the thread groove 135, and the upper end of the spring 132 is rotatably connected to the lower surface of the protective cover 14. Through this setting, on the one hand, can realize the elastic support to carousel 9, no matter carousel 9 level or slope, protection casing 14 all contact with carousel 9 all the time, slows down the degree that external vibration leads to carousel 9 vibrations during the measurement, and then reduces the measurement noise that laser interferometer 10 produced because of the vibration, improves data stability. On the other hand, by rotating the spring 132 so that the spring 132 extends into the screw groove 135, the height of the shield 14 and the elastic supporting force to the turntable 9 can be reduced, and conversely, the height of the shield 14 and the elastic supporting force to the turntable 9 can be increased. Naturally, if the spring 132 is separated from the screw groove 135, the spring 132, the upper tube 133 and the protection cover 14 may be removed together.
The driving member 6 includes a worm wheel 61, a worm 62 and a first motor 63, wherein the worm wheel 61 is fixedly connected to the first rotating shaft 5, the worm 62 is connected to the worm wheel 61, the worm 62 is fixedly connected to the lower surface of the base 1 through a bearing seat, and one end of the worm 62 is fixedly connected to the output end of the first motor 63. With this arrangement, the first motor 63 can drive the turbine 61 to rotate by the worm 62, thereby driving the first rotation shaft 5 to rotate.
The side portion of the U-shaped frame 8 is fixedly connected with a second motor 20, an output end of the second motor 20 is fixedly connected with a second rotating shaft 21, the second rotating shaft 21 is rotatably connected to the U-shaped frame 8, and the turntable 9 is fixedly connected to the middle portion of the second rotating shaft 21. When the second motor 20 is started, the output end of the second motor 20 drives the second rotating shaft 21 to rotate, the second rotating shaft 21 is rotatably connected to the U-shaped frame 8, and the angle of the laser interferometer 10 on the upper side of the turntable 9 is further adjusted along with the rotation of the second rotating shaft 21.
The device comprises a base 1, a support frame 22, a screw sleeve 26, a third motor 27, a screw rod 28, and a screw rod 28, wherein the support frame 22 is provided with support legs 23, a sliding rail 24 is fixed on the support frame 22, a sliding block 25 is fixedly connected to the lower side of the base 1, the sliding block 25 is slidably connected to the sliding rail 24, the screw sleeve 26 is fixedly connected to the lower surface of the base 1, the third motor 27 is fixedly connected to the support frame 22, the screw rod 28 is fixedly connected to an output shaft of the third motor 27, and the screw rod 28 is in threaded connection with the screw sleeve 26. With this arrangement, the third motor 27 drives the screw rod 28, and the base 1 is driven to slide along the slide rail 24 by the screw sleeve 26.
Example 2
On the basis of example 1, the following settings were also made:
Referring to fig. 1-12, the upper end of the upper tube 133 is communicated with the protective cover 14, a cylindrical air bag 15 is disposed in the upper tube 133, the upper end of the cylindrical air bag 15 extends into the protective cover 14, one side of the cylindrical air bag 15 is attached to the inner wall of the upper tube 133, a bar-shaped groove 16 (the cylindrical air bag 15 is shaped like a Chinese character 'hui', and does not affect the tightness) is disposed in the cylindrical air bag 15, a vertical rod 17 is fixedly connected to the inner portion of the lower tube 131, the vertical rod 17 is attached to the outer surface of the cylindrical air bag 15, a compression bar 18 is fixedly connected to the upper end of the vertical rod 17, and the compression bar 18 is located in the bar-shaped groove 16. The upper edge of the protection cover 14 is fixedly connected with a strip-shaped air bag 19, and the strip-shaped air bag 19 is communicated with the cylindrical air bag 15 through a hose. Further, a brush is fixedly connected to the upper end of the cylindrical air bag 15. When rotating 90 ° upwards from the front at the turntable 9, the brush can clean the laser head. And, the dimension from the upper surface of the turntable 9 to the second rotating shaft 21 is smaller than the dimension from the lower surface of the turntable 9 to the second rotating shaft 21.
With this arrangement, the following functions are provided:
In the state where the turntable 9 is faced upward, the pressing bar 18 is fitted to the lower side of the bar-shaped groove 16, but does not press the columnar air bag 15. In the process that the turntable 9 starts to rotate 180 degrees from the front side upwards, the turntable 9 presses the protective cover 14 and the upper pipe body 133 downwards, at this time, the cylindrical air bag 15 is not pressed by the pressing rod 18 (at this time, the pressing rod 18 moves in the strip-shaped groove 16), and the air pressure of the strip-shaped air bag 19 is small, so that the turntable 9 can rotate conveniently. Specifically, the strip-shaped air bag 19 is in a relaxed state under a low pressure state, only slightly contacts with the bottom surface of the turntable 9, and compared with a high pressure sealing state (the strip-shaped air bag 19 is expanded to be closely attached to the turntable 9), the friction resistance during rotation is reduced from sealing-stage resistance (the elastic deformation force of the strip-shaped air bag 19 needs to be overcome) to mechanical-stage resistance (only the slight contact force of the protective cover 14 and the turntable 9 needs to be overcome), so that the torque required by rotation of the turntable 9 is reduced. Until the front surface of the turntable 9 is downward, the protective cover 14 and the upper pipe body 133 automatically rise, and at this time, the protective cover 14 can cover the laser interferometer 10, thereby protecting. And because the size from the upper surface of the turntable 9 to the second rotating shaft 21 is smaller than the size from the lower surface of the turntable 9 to the second rotating shaft 21, when the turntable 9 faces downwards, the position of the upper pipe body 133 is higher, and therefore the pressure lever 18 downwards presses the cylindrical air bag 15, so that the air pressure of the strip-shaped air bag 19 is increased, the sealing between the protective cover 14 and the turntable 9 is realized, and the protective effect is improved. In this case, the bolt 12 can be removed by turning the nut while the front surface of the turntable 9 is facing downward, and the columnar airbag 15 can support the laser interferometer 10 from being broken because the upper end of the columnar airbag 15 extends into the protection cover 14.
Example 3
On the basis of example 1 or example 2, the following settings were also made:
Referring to fig. 13, the first rotating shaft 5 has a threaded hole 29 therein, a stud 30 is fixedly connected to the lower end of the lower tube 131, the lower end of the stud 30 penetrates through the U-shaped frame 8, and the stud 30 is fixedly connected to the threaded hole 29. By this arrangement, in addition to the lower pipe body 131, the U-shaped frame 8 can be installed, and the rapid disassembly of the U-shaped frame 8 is supported by screw connection.
The working principle of the invention is as follows:
In the base 1 part, the round hole 2 that base 1 middle part set up can be used to the location and the fixed when equipment is installed, ensures the stable placing of equipment in the tunnel. The fixed disk 3 of base 1 downside fixed connection inboard fixed joint spacing ring 4 is connected with driving piece 6 and swivel 7 on the first pivot 5 that fixed disk 3 rotated and is connected, and swivel 7 laminating is in spacing ring 4. When the laser interferometer 10 needs to be subjected to horizontal angle adjustment, the driving piece 6 drives the first rotating shaft 5 to rotate, and the first rotating shaft 5 drives the rotating ring 7 to stably rotate by 360 degrees under the limiting effect of the limiting ring 4. Because swivel 7 is spacing by spacing ring 4, and with swivel 7 fixed connection's U type frame 8 lower surface laminating in base 1 upper surface, this structural design has effectively restricted U type frame 8 and has rocked and slope in the rotation in-process, has guaranteed U type frame 8 pivoted stability. When the U-shaped frame 8 rotates, the turntable 9 and the laser interferometer 10 fixed on the U-shaped frame rotate along with the turntable, so that the angle adjustment of the laser interferometer 10 in the horizontal direction is realized, and surrounding rocks in different directions of a tunnel can be monitored. In the aspect of angle adjustment in the vertical direction, the turntable 9 is rotated, so that the angle of the laser interferometer 10 on the upper side of the turntable 9 is further adjusted, the angle change of the laser interferometer 10 in the vertical direction is realized, and surrounding rocks at different height positions such as the top and the side wall of a tunnel can be measured. Throughout the monitoring process, the laser interferometer 10 measures precisely the small displacement changes of the tunnel surrounding rock surface by emitting a laser beam, using the principle of laser interference. When the surrounding rock is deformed, the optical path of the reflected laser beam is changed, and the laser interferometer 10 converts the change of the optical path difference into specific displacement data by analyzing the change of the optical path difference, so that high-precision monitoring of the large deformation of the surrounding rock of the tunnel is realized.
It is noted that relational terms such as first and second, and the like are used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. Moreover, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus.
Although embodiments of the present invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made therein without departing from the principles and spirit of the invention, the scope of which is defined in the appended claims and their equivalents.