阅读说明：本技术 一种多点爆源同步起爆模拟装置 (Synchronous detonation simulation device for multi-point detonation source ) 是由 徐小辉 郭纬 李�杰 李干 王德荣 邵鲁中 姚瑶 张波 马超 孙慜倩 于 2021-08-30 设计创作，主要内容包括：本发明公开了一种多点爆源同步起爆模拟装置,包括防护罩、第一连接件、起爆线、不锈钢管、电雷管、黑索金、起爆器、起爆同步性检测装置、柔性导爆索、爆源装置。各路导爆索穿过不锈钢管彼此隔离防护,一端与各路爆源装置相连,另一端与同一电雷管锥形端相接,电雷管另一端与起爆器相连；各路导爆索和电雷管通过第一连接件相连,电雷管锥形端部可加入少量的黑索金粉保证导爆索同步起爆。各路离子电探针一端与各路起爆导爆索相接,另一端通过脉冲形成网络与示波器相连。爆源装置包括玻璃罩、导爆索、钢管、密封塞、空气压力调节装置。本发明的多点爆源装置同步起爆控制系统可用于大当量地下爆炸成坑效应的模拟,操作简单、起爆控制性强、同步性好。(The invention discloses a multipoint detonation source synchronous detonation simulation device which comprises a protective cover, a first connecting piece, a detonation wire, a stainless steel pipe, an electric detonator, a black cord, a detonator, a detonation synchronism detection device, a flexible detonation wire and a detonation source device. Each path of detonating cord penetrates through the stainless steel tube to be isolated and protected from each other, one end of each detonating cord is connected with each path of detonating source device, the other end of each detonating cord is connected with the conical end of the same electric detonator, and the other end of the electric detonator is connected with the detonator; each path of detonating cord is connected with the electric detonator through the first connecting piece, and a small amount of black cord metal powder can be added at the conical end part of the electric detonator to ensure synchronous detonation of the detonating cord. One end of each path of ion electric probe is connected with each path of detonating fuse, and the other end is connected with the oscilloscope through a pulse forming network. The explosion source device comprises a glass cover, an explosion wire, a steel pipe, a sealing plug and an air pressure adjusting device. The synchronous detonation control system of the multi-point detonation source device can be used for simulating the pit forming effect of large-equivalent underground explosion, and is simple to operate, strong in detonation control performance and good in synchronism.)

1. A multi-point detonating source synchronous detonation simulation device is characterized by comprising a detonator (1), an electric detonator (4), explosive powder (6), a plurality of paths of detonating cords (8), a detonating source device (12) correspondingly connected with each path of detonating cords, and a detonating synchronism detection device;

one end of the electric detonator (4) is conical;

the detonating cord (8) is arranged in the stainless steel tube (7) in a penetrating way to be isolated and protected from each other; one end of each detonating cord (8) is respectively connected with each detonating source device (12), and the other end is connected with the conical end of the same electric detonator (4); the other end of the electric detonator (4) is connected with the detonator (1) through the detonating cord (2);

each path of detonating cord (8) is connected with the electric detonator (4) through a first connecting piece (5), and explosive powder (6) is arranged at the conical end part of the electric detonator (4) to ensure synchronous detonation of each path of detonating cord (8); the explosive powder (6) is simultaneously connected with a plurality of detonating cords (8) and correspondingly sleeved with a plurality of stainless steel tubes (7); the electric detonator (4) and the explosive powder (6) are wrapped in the first connecting piece (5);

the detonation source device (12) is used for simulating single-point precise detonation;

the detonation synchronism detection device comprises a multi-channel ionic electric probe (9), a pulse forming network (10) and an oscilloscope (11);

one end of each path of the ionic electric probe (9) is correspondingly contacted with each path of the detonating fuse (8) respectively, the other end of each path of the ionic electric probe is connected to an oscilloscope (11) through a pulse forming network (10), and the synchronism of the detonating of each path of the detonating fuse (8) is measured and calculated through the oscilloscope (11).

2. The synchronous detonation simulator of multi-point sources according to claim 1, characterized in that said detonating cord (8) is a flexible detonating cord (8).

3. The multi-point detonation source synchronous detonation simulation device according to claim 1, characterized in that the detonation source device (12) comprises a glass cover (12-1), a detonating cord (8), a steel tube (12-3), a sealing plug (12-4), an air pressure adjusting device;

the bottom end of the glass cover (12-1) is sealed through a sealing plug (12-4), the detonating cord (8) connected to the detonation source device (12) is positioned in the glass cover (12-1), the detonating cord (8) penetrates out of the sealing plug (12-4) through the steel pipe (12-3), and the penetrating ends of the detonating cord (8) and the steel pipe (12-3) are sealed; the bottom end of the glass cover (12-1) is connected with an air pressure adjusting device.

4. The multi-point detonation source synchronous detonation simulation device according to claim 4, wherein the air pressure adjusting device comprises an air needle (12-5), a second connecting piece (12-6), an electromagnetic valve (12-7), a battery (12-8), a switch (12-9), a pressure buffer (12-12), a ball valve (12-13), a pressure gauge (12-10), a vacuum gauge (12-14), a pressure relief safety valve (12-11), an air compressor (12-15) and a vacuum pump (12-16);

the air needle (12-5) penetrates through the sealing plug (12-4) to be connected with the glass cover (12-1), the air needle (12-5) is connected with the electromagnetic valve (12-7) through the second connecting piece (12-6), and the other end of the electromagnetic valve (12-7) is connected with the pressure buffer (12-12); the air compressor (12-15), the vacuum pump (12-16), the pressure gauge (12-10) and the vacuum gauge (12-14) are all connected with the pressure buffer (12-12) through ball valves (12-13), and the pressure buffer (12-12) is also provided with a pressure relief safety valve (12-11); the battery (12-8) is connected with the electromagnetic valve (12-7) through the switch (12-9), and the battery (12-8) is used for powering on and powering off the electromagnetic valve (12-7) through the switch (12-9).

5. The synchronous detonation simulation device of a multi-point source of detonation according to claim 4, characterised in that the explosive powder (6) is hexogen powder.

6. The synchronous detonation simulator of claim 4, characterised in that the end of the detonating cord (8) in the source device (12) inside the glass envelope (12-1) is helical.

7. The synchronous detonation simulation device of the multipoint detonation source according to claim 4, characterized in that a glass cover (12-1) in the detonation source device (12) is of a cavity structure and comprises any one of a sphere, a cylinder and a polygon.

8. The multipoint detonation source synchronous detonation simulation device according to claim 2, wherein the contact positions of the ionic electric probes (9) of all paths and the flexible detonating cords (8) in the stainless steel pipes (7) are consistent, and the lengths of all paths of detonating cords (8) are consistent.

9. The synchronous detonation simulator of claim 1, characterised in that said source means (12) is a spherical or cylindrical pellet of micro-explosive.

Technical Field

The invention belongs to the technical field of multi-point detonating of detonating cords, and particularly relates to a synchronous detonation simulation device of a multi-point detonating source.

Background

The multiple warheads are used for carrying out 'collective explosion' near a target point, and the method is an effective mode for destroying deep underground target engineering in wartime. For a damage target, namely a natural rock mass, the movement, deformation and damage of the rock under the action of explosion are very complex, the mechanical parameter calculation is difficult to complete through theoretical analysis, the field test research period is long, the test risk is high, huge manpower and material resources are consumed, the repeatability is poor, and the system research is difficult to develop.

The simulation method is widely applied to different scientific fields, and the method adopting similar physical simulation tests can simulate the influence of various influencing factors on the formation of the crater and the bulge in the large-equivalent underground blasting process, so that people can more easily and comprehensively master the movement, deformation and destruction characteristics of the rock mass in the blasting process, and the method is an effective method for researching the underground blasting problem.

The current research shows that the vacuum chamber explosion model test device has obvious advantages in simulation of the large-equivalent large-buried depth underground explosion cratering phenomenon due to strong controllability and wide simulation application range. The detonation source device is a key device for simulating explosion of the vacuum chamber, in the scheme of the conventional detonation source device, the Russian realizes detonation mainly by a method of heating a nickel-chromium wire by a low-voltage power supply to crack a rubber airbag, the detonation time cannot be accurately controlled, only single-point detonation is realized, and a mature technical method is lacked for controlling the simultaneous accurate detonation of a multi-point detonation source device.

Disclosure of Invention

The invention aims to overcome the defects in the prior art and provide a synchronous detonation simulation device for a multi-point detonation source, so as to solve the problem that the multi-point detonation source device in the current vacuum chamber detonation simulation test device cannot be accurately and synchronously controlled in detonation.

In order to achieve the purpose, the invention is realized by adopting the following technical scheme:

the invention provides a synchronous detonation simulation device with multiple detonation sources, which comprises a detonator, an electric detonator, explosive powder, a plurality of detonating cords, a plurality of detonation source devices and a detonation synchronism detection device, wherein the detonator is connected with the electric detonator;

one end of the electric detonator is conical;

the detonating cords are arranged in the stainless steel tube in a penetrating way to be isolated and protected from each other; one end of each detonating cord is connected with each detonating source device, and the other end of each detonating cord is connected with the conical end of the electric detonator; the other end of the electric detonator is connected with the detonator through the detonating cord;

each path of detonating cord is connected with the electric detonator through a first connecting piece, and explosive powder is arranged at the conical end part of the electric detonator so as to ensure synchronous detonation of each path of detonating cord; multiple paths of detonating cords are simultaneously connected into the explosive powder, and multiple paths of stainless steel tubes are correspondingly matched with the explosive powder; the electric detonator and the explosive powder are wrapped by the first connecting piece;

the detonation source device is used for simulating single-point accurate detonation;

the detonation synchronism detection device comprises a multi-channel ionic electric probe, a pulse forming network and an oscilloscope;

one end of each path of the ionic electric probe is respectively contacted with each path of the detonating fuse, the other end of each path of the ionic electric probe is connected into an oscilloscope through a pulse forming network, and the synchronism of the detonating fuses of each path of the detonating fuse is measured and calculated through the oscilloscope.

Further, the detonating cord is a flexible detonating cord.

Furthermore, the explosion source device comprises a glass cover, an explosion wire, a steel pipe, a sealing plug and an air pressure adjusting device;

the bottom end of the glass cover is sealed through a sealing plug, the detonating cord connected to the detonation source device is positioned in the glass cover, the detonating cord penetrates out of the sealing plug through a steel pipe, and the penetrating end of the detonating cord and the penetrating end of the steel pipe are sealed; the bottom end of the glass cover is connected with an air pressure adjusting device.

Further, the air pressure adjusting device comprises an air needle, a second connecting piece, an electromagnetic valve, a battery, a switch, a pressure buffer, a ball valve, a pressure gauge, a vacuum gauge, a pressure relief safety valve, an air compressor and a vacuum pump;

the air needle penetrates through the sealing plug to be connected with the glass cover, the air needle is connected with the electromagnetic valve through a second connecting piece, and the other end of the electromagnetic valve is connected with the pressure buffer; the air compressor, the vacuum pump, the pressure gauge and the vacuum gauge are all connected with a pressure buffer through ball valves, and a pressure relief safety valve is further installed on the pressure buffer; the battery is connected with the electromagnetic valve through a switch, and the battery is used for powering on and powering off the electromagnetic valve through the switch.

Further, the explosive powder is hexogen powder.

Furthermore, one end of the detonating cord in the detonating source device, which is positioned in the glass cover, can be twisted into a spiral shape.

Furthermore, the contact positions of the ionic electric probes of all the paths and the flexible detonating cords in the stainless steel tube are kept consistent, and the lengths of the detonating cords of all the paths are consistent.

Furthermore, the glass cover in the source explosion device is of a cavity structure and comprises any one of a sphere, a cylinder and a polygon.

Further, the explosion source device is a spherical or cylindrical trace explosive ball.

Compared with the prior art, the invention has the following beneficial effects:

1. the synchronous detonation of each path of detonating cord is ensured by arranging the explosive powder at the conical end part of the electric detonator, the synchronous detonation of the paths of flexible detonating cords is ensured by respectively detonating the paths of flexible detonating cords by the same electric detonator, the synchronism of the detonation can be effectively ensured, and the electric detonator and the explosive powder are wrapped by the first connecting piece, so that the sealing effect is better, and the synchronous detonation of the multi-point detonating source device in a large-equivalent underground detonation crater effect simulation experiment can be realized.

2. The invention simultaneously detonates the multi-path flexible detonating cords by the electric detonator, adopts the ionic probe method to test the synchronism of the detonating, has good synchronism and a method for verifying the consistency, and is beneficial to improving the accuracy of the test.

3. The explosion source device can be used for simulating and researching the underground large equivalent explosion throwing phenomenon under the conditions of spherical explosive charging and cylindrical explosive charging and also can be used for simulating and researching the high-pressure gas explosion phenomenon in water and air through the air pressure adjusting device, and the universality is high.

Drawings

FIG. 1 is a schematic diagram of a detonation control system.

Fig. 2 is a schematic view of an explosion source device.

In the figure: 1. an initiator; 2. a detonating cord; 3. a protective cover; 4. an electric detonator; 5. a first connecting member; 6. explosive powder; 7. a stainless steel tube; 8. a detonating cord; 9. an ionic electric probe; 10. a pulse forming network; 11. an oscilloscope; 12. a source explosion device; 12-1, a glass cover; 12-2, the tail end of the detonating cord; 12-3, steel pipes; 12-4, a sealing plug; 12-5, air needle; 12-6, a second connecting piece; 12-7, an electromagnetic valve; 12-8, a battery; 12-9, a switch; 12-10 parts of a pressure gauge; 12-11, a pressure relief safety valve; 12-12, a pressure buffer; 12-13, ball valve; 12-14, a vacuum gauge; 12-15, an air compressor; 12-16 and a vacuum pump.

Detailed Description

The invention is further described below with reference to the accompanying drawings. The following examples are only for illustrating the technical solutions of the present invention more clearly, and the protection scope of the present invention is not limited thereby.

In the description of the present embodiment, it should be noted that, as the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc. appear, the indicated orientation or positional relationship thereof is based on the orientation or positional relationship shown in the drawings, and is only for convenience of describing the present embodiment and simplifying the description, but does not indicate or imply that the referred device or element must have a specific orientation, be configured and operated in a specific orientation, and thus, cannot be construed as limiting the present embodiment.

The first embodiment is as follows:

as shown in fig. 1, the present embodiment provides a multi-point detonation source synchronous detonation simulation device, which includes a detonator 1, an electric detonator 4, explosive powder 6, a multi-path detonating cord 8 and a plurality of detonation source devices 12;

one end of the electric detonator 4 is conical;

the detonating cords 8 are isolated and protected from each other by penetrating in the stainless steel tube 7; one end of each detonating cord 8 is respectively connected with each detonating source device 12, and the other end is connected with the conical end of the electric detonator 4; the other end of the electric detonator 4 is connected with the initiator 1 through the initiation wire 2;

each path of detonating cord 8 is connected with the electric detonator 4 through the first connecting piece 5, and the conical end part of the electric detonator 4 is provided with explosive powder 6 to ensure synchronous detonation of each path of detonating cord 8; the electric detonator 4 and the explosive powder 6 are both wrapped in the first connecting piece 5;

the detonation source device 12 realizes the simulation of the accurate detonation of the single-point detonation source device 12 by adopting a mode that shock waves generated by the detonation and the propagation of the flexible detonating cord strike the glass ball cover.

The implementation principle is as follows: when the control system is detonated, the electric detonator 4 is detonated by the detonator 1, further the explosive powder 6 is detonated, the multi-path flexible detonating cords 8 embedded in the explosive powder 6 are synchronously detonated, the shock waves generated by the detonating cords 8 are used for breaking the detonating source device 12 to achieve the effect of simulating explosion, the explosive powder 6 is arranged at the conical end part of the electric detonator 4 to ensure that the detonating cords 8 of each path are synchronously detonated, and the electric detonator 4 and the explosive powder 6 are both wrapped in the first connecting piece 5, so that the sealing effect is better, the control system can be used for simulating the pit forming effect of large-equivalent underground explosion, is simple in operation, strong in detonating control and good in synchronism, and solves the problem that the multi-point detonating sources in the current vacuum chamber explosion simulation test device cannot be accurately and synchronously detonated.

Example two:

referring to fig. 1, the multi-point detonation source synchronous detonation simulation device of the invention comprises a detonator 1, a detonation wire 2, an electric detonator 4, a flexible detonating cord 8, a detonation synchronism detection device and a detonation source device 12.

The detonating cords 8 pass through the stainless steel tube 7 to be isolated and protected from each other, one end of each detonating cord is connected with each detonating source device 12, the other end of each detonating cord is connected with the conical end of the same electric detonator 4, and the other end of the electric detonator 4 is connected with the detonator 1; each path of detonating cord 8 is connected with the electric detonator 4 through the first connecting piece 5, and a small amount of explosive powder 6 can be added at the conical end part of the electric detonator 4 to ensure synchronous detonation of the detonating cord 8; the electric detonator 4 and the explosive powder 6 are both wrapped inside by the first connecting piece 5. The first connecting piece 5 is covered with a protective cover 3 to prevent the explosion shock wave from damaging the surrounding environment. .

The detonation synchronism detection device comprises an ionic electric probe 9, a pulse forming network 10 and an oscilloscope 11. One end of an ionic electric probe 9 is embedded into the end part of the stainless steel pipe 7 and is contacted with the flexible detonating cord 8, the other end of the ionic electric probe is connected with a lead, and the lead is connected into an oscilloscope 11. The electric detonator 4 detonates the multi-path flexible detonating cord 8 at the same time, and the ionic electric probe 9 method is adopted to test the synchronism of the detonating, so that the synchronism is good. The ionic electric probe 9, the pulse forming network 10 and the oscilloscope 11 are accurate in measurement, and accurate test is facilitated.

Referring to fig. 2, the explosion source device 12 includes a glass cover 12-1, an explosion wire 8, a steel pipe 12-3, a sealing plug 12-4, and an air pressure adjusting device. The bottom end of the glass cover 12-1 is sealed by a sealing plug 12-4, the detonating cord 8 connected to the detonation source device 12 is positioned in the glass cover 12-1, the detonating cord 8 penetrates out of the sealing plug 12-4 through a steel pipe 12-3, and the penetrating end of the detonating cord 8 and the steel pipe 12-3 is sealed; the bottom end of the glass cover 12-1 is connected with an air pressure adjusting device.

The tail end 12-2 of the detonating cord 8 positioned in the glass cover 12-1 is twisted into a spiral shape to increase the length of the detonating cord 8 at the center of the glass cover 12-1 and ensure the spherical explosion effect of the detonating cord 8 which transmits shock waves to the periphery at the center of the glass cover 12-1. The detonating cord 8 may also be of other shapes.

The explosive powder 6 can be simultaneously connected with a plurality of paths of flexible detonating cords 8 and correspondingly matched with a plurality of paths of stainless steel tubes 7 and an ion electric probe 9, and the explosive powder 6 is preferably hexogen powder and can be replaced by other explosive powder 6.

The contact positions of the ionic electric probes 9 of all paths and the flexible detonating cords 8 in the stainless steel tube 7 are consistent, and the lengths of the detonating cords 8 of all paths are consistent. This is beneficial to further improve the synchronism and make the test more accurate.

The glass cover 12-1 in the explosion source device 12 can be a cavity structure with a spherical shape, a cylindrical shape, a polygonal shape or other shapes.

Alternatively, the source of detonation 12 may be reduced to a spherical, cylindrical, or other shaped pellet of micro-explosive.

Referring to fig. 2, the air pressure adjusting device is used for adjusting the air pressure in the glass cover 12-1 and comprises an air needle 12-5, a second connecting piece 12-6, an electromagnetic valve 12-7, a battery 12-8, a switch 12-9, a pressure buffer 12-12, a ball valve 12-13, a pressure gauge 12-10, a vacuum gauge 12-14, a pressure relief safety valve 12-11, an air compressor 12-15 and a vacuum pump 12-16.

The air needle 12-5 penetrates through the sealing plug 12-4 to be connected with the glass cover 12-1, the air needle 12-5 is connected with the electromagnetic valve 12-7 through the second connecting piece 12-6, and the other end of the electromagnetic valve 12-7 is connected with the pressure buffer 12-12; the air compressor 12-15, the vacuum pump 12-16, the pressure gauge 12-10 and the vacuum gauge 12-14 are all connected with the pressure buffer 12-12 through the ball valve 12-13, and the pressure buffer 12-12 is also provided with a pressure relief safety valve 12-11; the ball valve 12-13 is used for controlling the connection or the disconnection of the air compressor 12-15 or the vacuum pump 12-16 and the pressure buffer 12-12; when the pressure buffer 12-12 is communicated with the air compressor 12-15, the pressure gauge 12-10 is used for measuring the pressure in the pressure buffer 12-12, namely the pressure in the glass cover 12-1; the vacuum gauge 12-14 is used to measure the degree of vacuum in the pressure buffer 12-12, i.e., in the glass envelope 12-1, when the pressure buffer 12-12 is in communication with the vacuum pump 12-16; the battery 12-8 is connected with the electromagnetic valve 12-7 through the switch 12-9, and the battery 12-8 switches on or off the electromagnetic valve 12-7 through the switch 12-9.

When the test requires that the gas pressure in the glass cover 12-1 exceeds the atmospheric pressure, the vacuum pump 12-16 and the corresponding ball valve 12-13 on the vacuum gauge 12-14 are closed, the air compressor 12-15, the pressure gauge 12-10 and the starting switch 12-9 are opened, the pressure buffer 12-12 is inflated, the inflation is stopped when the required pressure is reached, the switch 12-9 is disconnected, and at the moment, a certain amount of gas is filled in the glass cover 12-1.

When the gas pressure in the glass cover 12-1 is lower than the atmospheric pressure, the air compressor 12-15 and the corresponding ball valve 12-13 on the pressure gauge 12-10 are closed, the vacuum pump 12-16 and the corresponding ball valve 12-13 and the opening switch 12-9 on the vacuum gauge 12-14 are opened, the pressure buffer 12-12 is pumped, when the required vacuum degree is reached, the air pumping is stopped, the switch 12-9 is closed, the inner part of the glass cover 12-1 reaches a certain pressure, the electric detonator 4 is detonated by the initiator 1, further the explosive powder 6 is detonated, the multi-path flexible detonating cord 8 embedded in the explosive powder 6 is synchronously detonated, and the glass cover 12-1 is broken by the shock wave generated by the detonating cord 8 so as to achieve the purpose of releasing the compressed gas. Meanwhile, the ionic electric probe 9 in the stainless steel pipe 7 transmits signals into the pulse forming network 10 and then transmits the signals into the oscilloscope 11, and the synchronism of the multipoint source explosion device 12 is determined through the pulse time difference of the oscilloscope 11.

Compared with the prior art, the invention has the following remarkable advantages:

(1) the method can be used for synchronous detonation of multi-point detonation sources in large-equivalent underground explosion crater effect simulation experiments.

(2) The electric detonator 4 detonates the multi-path flexible detonating cord 8 at the same time, and the ionic electric probe 9 method is adopted to test the synchronism of the detonating, so that the synchronism is good.

(3) The universality is strong: the detonation source control system can be used for simulating and researching the underground large equivalent detonation throwing phenomenon under the conditions of spherical charging and cylindrical charging, and can also be used for simulating and researching the high-pressure gas detonation phenomenon in water and air.

Furthermore, the terms "first", "second" and "first" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature, and in the description of the invention, "plurality" means two or more unless explicitly specifically defined otherwise.

In the present invention, unless otherwise specifically stated or limited, the terms "mounted," "connected," "fixed," and the like are to be construed broadly and may, for example, be fixedly connected, detachably connected, or integrally connected; can be mechanically or electrically connected; they may be connected directly or indirectly through intervening media, or they may be interconnected between two elements. The specific meanings of the above terms in the present invention can be understood by those skilled in the art according to specific situations.

In the present invention, unless otherwise expressly stated or limited, "above" or "below" a first feature means that the first and second features are in direct contact, or that the first and second features are not in direct contact but are in contact with each other via another feature therebetween. Also, the first feature being "on," "above" and "over" the second feature includes the first feature being directly on and obliquely above the second feature, or merely indicating that the first feature is at a higher level than the second feature. A first feature being "under," "below," and "beneath" a second feature includes the first feature being directly above and obliquely above the second feature, or simply meaning that the first feature is at a lesser level than the second feature.

In the description herein, reference to the terms "one embodiment," "some embodiments," "an example," "a specific example," or "some examples" or the like means that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the invention. In this specification, the schematic representations of the terms used above do not necessarily refer to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.

Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention, and that variations, modifications, substitutions and alterations can be made in the above embodiments by those of ordinary skill in the art without departing from the principle and spirit of the present invention.