Patent Publication Number: US-2015059435-A1

Title: Method and system for detecting components in a fluid

Description:
BACKGROUND 
     The subject matter disclosed herein generally relates to detection systems and in particular, to a detection system for measuring at least one of a component and concentration of the component in a fluid using a photo acoustic spectroscopy (PAS) technique. 
     Electrical equipment, such as transformers, use fluids having good thermal and insulation properties to encapsulate components of the electrical equipment in a containment vessel for enabling dissipation of heat generated from a coil. The fluid may be an oil such as castor oil, mineral oil, synthetic oil such as chlorinated diphenyl silicone oil, or the like. 
     Failure of electrical equipment or components of the electrical equipment, such as coils of a transformer, may result in disruption of operation. Monitoring of the electrical equipment to predict potential failures through detection of incipient faults is desirable. A known method of monitoring the electrical equipment involves analysis of various parameters of the fluid that circulates about the equipment. 
     Presence of total combustible gas (TCG) in the fluid is known to provide information about operating state of the electrical equipment immersed in the fluid. To enable early detection of faults, the dissolved gases within the fluid are analyzed. Presence of gaseous components such as carbon monoxide, carbon dioxide, or the like and their concentrations, for example may be indicative of thermal aging of the equipment. Similarly, gaseous components such as hydrogen, hydrocarbons, or the like may be indicative of a dielectric breakdown among other faults. 
     Known methods for analyzing dissolved gases such as Gas Chromatography (GC), Optical Spectroscopy, and Photo Acoustic Spectroscopy (PAS), require the extraction of gases from the fluid. The known extraction techniques such as vacuum extraction, and head space extraction methods suffer from drawbacks such as repeatability issues and increased complexity. 
     There is a need for an enhanced technique to measure at least one of a component and concentration of the component in a fluid used in electrical equipment. 
     BRIEF DESCRIPTION 
     In accordance with one aspect, a system for detecting components in a sample fluid is disclosed. The system includes a first chamber having the sample fluid and a second chamber coupled to the first chamber, wherein the second chamber has a reference fluid. The system also includes a modulated light source for emitting a modulated light beam to the sample fluid and the reference fluid, to generate a first acoustic signal in the first chamber and a second acoustic signal in the second chamber. The system further includes a pressure sensor disposed between the first chamber and the second chamber, for detecting a difference between the first acoustic signal and the second acoustic signal. The system includes a processor based module communicatively coupled to the pressure sensor and configured to receive a signal representative of the difference from the pressure sensor and determine at least one of a component and a concentration of the component in the sample fluid based on the signal representative of the difference. 
     In accordance with another aspect, a method for detecting components in a sample fluid is disclosed. The method includes emitting a modulated light beam to the sample fluid in a first chamber and a reference fluid in a second chamber, wherein the second chamber is coupled to the first chamber. The method also includes generating a first acoustic signal in the first chamber and a second acoustic signal in the second chamber, in response to the emitted modulated light beam. The method further includes detecting a difference between the first acoustic signal and the second acoustic signal via a pressure sensor disposed between the first chamber and the second chamber. The method also includes transmitting a signal representative of the difference from the pressure sensor to a processor based module and determining at least one of a component and a concentration of the component in the sample fluid via the processor based module, based on the signal representative of the difference. 
    
    
     
       DRAWINGS 
       These and other features and aspects of embodiments of the present invention will become better understood when the following detailed description is read with reference to the accompanying drawings in which like characters represent like parts throughout the drawings, wherein: 
         FIG. 1  is a diagrammatic illustration of an electrical utility monitored in accordance with an exemplary embodiment; 
         FIG. 2  illustrates a detection system in accordance with an exemplary embodiment; 
         FIG. 3  illustrates relative positions of a center of a pressure wave front and a pressure sensor in accordance with an exemplary embodiment; 
         FIG. 4  illustrates a graph showing variation of pressure waveform detected by a pressure sensor in accordance with an exemplary embodiment; 
         FIG. 5  illustrates a side-by-side arrangement of a detection system in accordance with an exemplary embodiment; 
         FIG. 6  illustrates a top view of the side-by-side arrangement of a detection system in accordance with an exemplary embodiment; 
         FIG. 7  illustrates a concentric arrangement of a detection system in accordance with an exemplary embodiment; 
         FIG. 8  illustrates of a detection system having a single enclosure partitioned into two chambers; 
         FIG. 9  a graph representative of variation in amplitude of a photo acoustic pressure wave corresponding to a reference liquid in accordance with an exemplary embodiment; 
         FIG. 10  is a graph representative of variation in amplitude of a photo acoustic pressure wave corresponding to a component in a sample fluid in accordance with an exemplary embodiment; 
         FIG. 11  is a graph representative of an absorption spectrum of a reference liquid in accordance with an exemplary embodiment; 
         FIG. 12  is a graph representative of an absorption spectra corresponding to a plurality of gaseous components in accordance with an exemplary embodiment; and 
         FIG. 13  is a flow chart illustrating exemplary steps involved in detecting a component dissolved in a liquid in accordance with an exemplary embodiment. 
     
    
    
     DETAILED DESCRIPTION 
     Embodiments relate to systems and methods for detecting the presence of a component in a fluid using a spectroscopic method. Specifically, a technical effect is that in certain embodiments, the composition and concentration of a dissolved gas in a liquid is determined using photo acoustic spectroscopy (PAS) technique. A light beam from a modulated light source is emitted on a sample fluid in a first chamber and a reference fluid in a second chamber coupled to the first chamber. A pressure sensor disposed between the first chamber and the second chamber, measures a difference between a first acoustic signal generated in the first chamber and a second acoustic signal generated in the second chamber. A processor based module which is communicatively coupled to the pressure sensor, receives a signal representative of the difference from the pressure sensor and determines at least one of a component and a concentration of the component in the sample fluid based on the signal representative of the difference. 
       FIG. 1  illustrates an electrical utility  100  incorporating an exemplary system for inspection of equipment disclosed herein. The electrical utility  100  has an electrical infrastructure  102  having equipment  104 ,  106  which are to be inspected. In the illustrated embodiment, the equipment  104 , 106  are transformers. The equipment  104  is monitored by an exemplary inspection system  108  and the equipment  106  is monitored by another exemplary inspection system  110 . Further, a portable diagnostic subsystem  114  may be used by a mobile operator  112  for quick and accurate diagnostics of the health of the equipment  104 ,  106 . Additionally, the electrical utility  100  may also be equipped with a remote monitoring and diagnostic subsystem  116  for providing continuous asset monitoring capability. The remote monitoring in this example includes online fault monitoring and trending of faults to predict failure of the equipment  104 ,  106 . It should be noted herein that the illustrated electrical utility  100  should not be construed as a limitation. In other words, the exemplary inspection systems are applicable for other applications in which there is a requirement for detecting the presence of a component in a fluid. 
       FIG. 2  illustrates a detection system  200  used in at least one of the inspection systems  108 ,  110  in accordance with an exemplary embodiment. The system  200  includes a modulated light source  202  for emitting a modulated light beam  220  to a sample fluid  232  filled in a first chamber  218  to generate a “first acoustic signal”  238 . The “first acoustic signal”  238  referenced herein is a pressure signal generated by fluctuations in temperature of the sample fluid  232 , wherein the fluctuations in temperature are caused by the modulated light beam  220 . The modulated light source  202  further emits a modulated light beam  222  to a reference fluid  234  filled in a second chamber  216 , to generate a “second acoustic signal”  240 . The “second acoustic signal”  240  referenced herein is a pressure signal generated by fluctuations in temperature in the reference fluid  234 , wherein the fluctuations in temperature are caused by the modulated light beam  222 . In the illustrated embodiment, there is a single light source  206  that employs optics  204 ,  214 ,  215  to generate the modulated light beams  220 ,  222 . In an alternate embodiment, the modulated light source  202  includes a first modulated light source for emitting modulated light beam  220  and a second modulated light source for emitting modulated light beam  222 . 
     In the illustrated embodiment, the modulated light source  202  includes a light source  206  for generating the light beam  254  and a modulator device  208  for generating modulated light beams  220 ,  222 . In one embodiment, the light source  206  is a laser light source. In alternate embodiments, the light source  206  may be a broad band light source, a tunable diode (TD) laser, or a quantum cascade laser source. In the illustrated embodiment, the modulated light source  202  includes a reflector  204  used for reflecting the light beam  254  from the light source  206 . 
     The modulator device  208  modulates the light beam  254  from the light source  206  via the reflector  204  by controlling at least one of an intensity of the light beam, a wavelength of the light beam, parameters of the light source  206  and/or characteristics of the reflector  204 . In the illustrated embodiment, the modulator device  208  includes a rotatable disc  209  with a plurality of slots  210 . The rotatable disc  209  is used for generating a modulated light beam in the form of light pulses via the slots  210 . In alternate embodiments, the modulator device  208  may be used to modulate the intensity of the light beam  254  from the light source  206  by other suitable techniques. In one specific embodiment, the modulator device  208  may be used to modulate the wavelength of the light beam. In some embodiments, the modulator device  208  may also be a part of the light source  206 . In certain embodiments, the light beam  254  from the light source  206  may be modulated by varying one of more parameters of the light source  206 . In one embodiment, the temperature of the light source  206  may be modified to generate a modulated light beam. In another embodiment, the current used for powering the light source  206 , may be varied to generate a modulated light beam. The modulated light beam has a range of wavelength suitable for detecting the presence of one or more components in the fluid. 
     In the illustrated embodiment, the modulated light source  202  includes a reflector  204  and the light source  206 . The light source  206  generates a light beam that strikes the reflector  204  and produces a reflected light beam  254 . the modulated light source  202  also includes a filter  212  for filtering the light beam  254 , corresponding to the required wavelength. In a specific embodiment, the filter  212  includes a plurality of filter lenses having different wavelengths. Further, a beam splitter  214  and a reflector  215  are used to generate modulated light beams  220 ,  222  from a filtered output of the filter  212 . In the illustrated embodiment, two modulated light beams  220 ,  222  are generated from a single modulated light source  202 . In another embodiment, two laser sources may be used to generate two modulated light beams. 
     In the illustrated embodiment, the sample fluid  232  includes a component  230  dissolved in a sample liquid  242  and the reference fluid  234  includes a reference liquid  244 . In another embodiment, the sample fluid may be a suspension having a component in the sample liquid. In an exemplary embodiment, the sample liquid  242  and the reference liquid  244  may be an insulation oil used in the components to be inspected, for example a transformer. The component  230  may be at least one of gaseous components such as acetylene, hydrogen, methane, ethane, ethylene, carbon dioxide, carbon monoxide, moisture, or the like. In one embodiment, the constituents of the sample liquid  242  may be exactly same as the constituents of the reference liquid  244 . In another embodiment, the constituents of the sample liquid  242  may be substantially same as the constituents of the reference liquid  244 . 
     The first acoustic signal  238  generated in the first chamber  218 , includes a third acoustic signal  246  generated due to the presence of the sample liquid  242  and a fourth acoustic signal  248  generated due to the presence of the component  230 . The “third acoustic signal”  246  referenced herein is a pressure signal generated due to fluctuations in temperature of the sample liquid  242  generated by the modulated light beam  220 . The “fourth acoustic signal”  248  is a pressure signal generated due to fluctuations in temperature of the component  230  generated by the modulated light beam  220 . The “second acoustic signal”  240  referred herein is a pressure signal generated due to fluctuations in temperature of the reference liquid  244  generated by the modulated light beam  222 . In the illustrated embodiment, a light absorption spectrum corresponding to the sample liquid  242  is the same as a light absorption spectrum corresponding to the reference liquid  244 . A light absorption spectrum corresponding to the component  230  is different from a light absorption spectrum corresponding to the sample liquid  242 . 
     In the illustrated embodiment, the first chamber  218  is coupled to the second chamber  216  and separated from each other by a diaphragm  224 . A pressure sensor  236  is disposed in the diaphragm  224  between the first chamber  218  and the second chamber  216 . The first acoustic signal  238  is transmitted to a first side  250  of the pressure sensor  236  and the second acoustic signal  240  is transmitted to a second side  252  opposite to the first side  250  of the pressure sensor  236 . The third acoustic signal  246  corresponding to the sample liquid  242  is transmitted to the first side  250  of the pressure sensor  236 . In an embodiment where the constituents of the sample liquid  242  are the same as the constituents of the reference liquid  244 , the third acoustic signal  246  neutralizes or cancels the second acoustic signal  240  corresponding to the reference liquid  244 . In another embodiment where the constituents of the sample liquid  242  are substantially the same as the constituents of the reference liquid  244 , the third acoustic signal  246  substantially neutralizes the second acoustic signal  240 . In one example, the third acoustic signal  246  is reduced by about 80 dB. In other embodiments, the reduction would be in the range of about 40 to 100 dB. 
     The pressure sensor  236  detects a difference between the first acoustic signal  238  and the second acoustic signal  240  and generates a signal representative of the difference. In other words, the pressure sensor  236  detects the pressure signal which is representative of the component  230 . 
     In one embodiment, the pressure sensor  236  is positioned in the diaphragm  224 . In an alternate embodiment, the diaphragm  224  may be the pressure sensor separating the first chamber  218  from the second chamber  216 . In one embodiment, the pressure sensor  236  is a piezo-based pressure sensor. In such an embodiment, the pressure sensor  236  may employ a piezo-electric effect or a piezo-resistance effect to detect the difference between the first acoustic signal  238  and the second acoustic signal  240 . In certain other embodiments, the pressure sensor  236  may be a cantilever-based pressure sensor or a membrane based pressure sensor, a microphone, a hydrophone or a capacitance based sensor. 
     A processor-based module  228  is communicatively coupled to the pressure sensor  236 , and configured to receive the signal representative of the difference between the first acoustic signal  238  and the second acoustic signal  240  from the pressure sensor  236 . The processor-based module  228  is also configured to determine at least one component and a concentration of the component  230  in the sample fluid  232  based on the signal representative of the difference between the first acoustic signal  238  and the second acoustic signal  240 . 
     The processor-based module  228  may include a controller, a general purpose processor, or an embedded system. The processor-based module  228  may receive additional inputs from a user through an input device such as a keyboard or a control panel. The processor-based module  228  may also be communicatively coupled to a memory module such as a random access memory (RAM), read only memory (ROM), flash memory, or other type of computer readable memory. Such a memory module may be encoded with a program to instruct the processor-based module  228  to enable a sequence of steps to determine at least one of the components and the concentration of the component  230 . In an alternate embodiment, all the components of the exemplary detection system  200  may be incorporated as a single stand-alone module integrated with inspection systems  108 ,  110  (shown in  FIG. 1 ). 
       FIG. 3  is a schematic diagram  300  illustrating relative positions of a center of a pressure wave front and a pressure sensor used to measure the acoustic (or pressure) signal in accordance with an exemplary embodiment. In the illustrated embodiment, a rectangle  302  is representative of a chamber and a point  304  is representative of a location in the chamber where the modulated light beam is received by a fluid in the chamber represented by the rectangle  302 . Specifically, the point  304  is indicative of the center of the pressure wave front generated in the fluid due to the modulated light beam. In one embodiment, the rectangle  302  may be representative of the first chamber and the point  304  is indicative of the center of a pressure wave representative of the first acoustic signal. In another embodiment, the rectangle  302  may be representative of the second chamber and the point  304  is indicative of the center of a pressure wave representative of the second acoustic signal. In the illustrated embodiment, the pressure sensor  306  is disposed at a position with reference to the rectangle  302 . Although, in the illustrated embodiment, the center of the pressure wave is represented as the point  304 , in other embodiments, the pressure wave may also be generated along a line created by the modulated light beam along the line to the fluid filled in the chamber. 
       FIG. 4  illustrates a graph  400  showing variation of a pressure wave front in accordance with an exemplary embodiment of  FIG. 3 . The x-axis  402  of the plot graph is representative of the time in microseconds and y-axis  404  of the graph  400  is representative of pressure in Pascal. The waveform  406  is representative of a pressure wave detected by the pressure sensor. 
       FIG. 5  illustrates a side-by-side arrangement of a detection system  500  in accordance with an exemplary embodiment. In the illustrated embodiment, a first chamber  502  is coupled to a second chamber  504  and disposed side-by-side. A pressure sensor  506  is disposed along a vertical plane between the first chamber  502  and the second chamber  504 . The modulated light beams  508 ,  510  are emitted along a vertical direction into the first and second chambers  502 ,  504  respectively. In another embodiment, the modulated light beams  508 ,  510  may be emitted along a horizontal direction and the pressure sensor  506  may be disposed along a horizontal plane between the first chamber  502  and the second chamber  504 . 
       FIG. 6  illustrates a top view of an exemplary detection system  600 . In the illustrated embodiment, the detection system  600  includes a circular first chamber  602  coupled to a circular second chamber  604 . The pressure sensor  606  is disposed between the circular first chamber  602  and the circular second chamber  604 . The embodiments discussed herein are not restrictive and the first chamber  602  and the second chamber  604  may be disposed in any other manner so as to substantially remove the common signal (also called ‘common mode signal’) between the first acoustic signal and the second acoustic signal. While the embodiments discussed herein depict only two chambers, exemplary techniques are applicable to systems with more than two chambers. The use of multiple chambers can provide for redundancy as well as detection of multiple components. 
       FIG. 7  illustrates a top view of a concentric arrangement of a detection system  700  in accordance with an exemplary embodiment. The detection system  700  includes a first chamber  702  and a second chamber  704  disposed concentrically within the first chamber  702 . Both the first chamber  702  and the second chamber  704  are cylindrical shaped. In the illustrated embodiment, a diaphragm  706  is disposed between the first chamber  702  and the second chamber  704 . A pressure sensor  708  is disposed within the diaphragm  706 . Alternatively, the diaphragm  706  itself may be the pressure sensor. 
       FIG. 8  illustrates another exemplary embodiment of a detection system  800 . The detection system  800  includes single enclosure  802  partitioned by a diaphragm  804  to form a first chamber  806  and a second chamber  808 . The diaphragm  804  includes a pressure sensor  810  for measuring a difference between a first pressure wave generated in the first chamber  806  and a second pressure wave generated in the second chamber  808 . In another embodiment diaphragm  804  itself may be the pressure sensor. 
       FIG. 9  illustrates a graph  900  showing variation of an amplitude of a photo acoustic pressure wave corresponding to the reference liquid in accordance with an exemplary embodiment. In the graph  900 , the x-axis  902  is representative of a concentration in ppm (parts per million) and the y-axis  904  is representative of a peak pressure in Pascal. The curve  906  is representative of the amplitude of the photo acoustic pressure wave generated due to the reference liquid. It may be noted herein that the amplitude value of 4.7×10 5  Pa is higher compared to the amplitude of the photo acoustic pressure wave generated due to the component dissolved in the sample liquid in accordance with the embodiment shown in the subsequent  FIG. 10 . 
       FIG. 10  illustrates a graph  1000  representative of an amplitude of a photo acoustic pressure wave corresponding to the component dissolved in the sample liquid in accordance with an exemplary embodiment. In the graph  1000 , the x-axis  1002  is representative of concentration in ppm (parts per million) and the y-axis  1004  is representative of peak pressure in Pascal. The curve  1006  is representative of the amplitude of the photo acoustic pressure wave generated due to the component dissolved in the sample liquid. In the illustrated embodiment, the amplitude value of the curve  1006  is in the range of 0 Pa-12 Pa which is smaller compared to the amplitude value of the reference liquid illustrated in  FIG. 9 . 
       FIG. 11  illustrates a graph  1100  representative of an absorption spectrum corresponding to an insulation oil (with a 0.5 mm of path length) of a transformer system, for example, in accordance with an exemplary embodiment. The x-axis  1102  of the graph  1100  is representative of wavenumber (indicated in cm −1 ) and the y-axis  1104  of the graph  1100  is representative of an absorbance in percentage values. The curve  1106  is representative of the absorption spectrum of the insulation oil having a minimum absorbance value of about 50% at wavenumbers 2000 cm −1  and 3500 cm −1  represented by numerals  1108 ,  1110  respectively. 
       FIG. 12  illustrates a graph  1200  representative of absorption spectra corresponding to a plurality of gaseous components (having 500 ppm, and 1 mm path length) in accordance with an exemplary embodiment. The x-axis  1202  of the graph  1200  is representative of wavenumber (in cm −1 ) and the y-axis  1204  of the graph  1200  is representative of an absorbance in percentage values. The curve  1206  is representative of the absorption spectrum of carbon dioxide, the curve  1208  is representative of an absorption spectrum of methane, and the curve  1210  is representative of an absorption spectrum of acetylene. In the graph  1200 , acetylene exhibits a peak absorbance value of 0.05% corresponding to a wavenumber of 3300 cm −1  represented by reference numeral  1212 , methane exhibits a peak absorbance value of 0.2% corresponding to a wavenumber of 3100 cm −1  represented by reference numeral  1214 , and carbon dioxide exhibits a peak absorbance value of 1.4% (not shown in the graph) corresponding to wavenumber of 2300 cm −1 . It may be noted herein that the peak absorbance values corresponding to gaseous components illustrated in  FIG. 12  are lower compared to the peak absorbance value of the insulation oil. It should be noted herein that all the values in the various embodiments discussed herein should not be construed as a limitation of the invention. 
       FIG. 13  is a flow chart  1300  illustrating exemplary steps involved in a detection method in accordance with an exemplary embodiment. The method includes generating a modulated light beam  1302  by modulating at least one of an intensity of a light beam  254  and a wavelength of the light beam. The light beam is generated by a light source such as a laser source. The modulated light beam is transmitted to a sample fluid in a first chamber  1304 . The sample fluid includes a sample liquid and a component dissolved in the sample liquid. The modulated light beam has a beam wavelength within a range of a spectral absorption wavelength of the component in the sample fluid. In the method discussed herein, in one embodiment, the sample liquid in the sample fluid may be an insulation oil in a transformer system. The emitted modulated light generates a modulated heat flux within the sample fluid. Propagation of modulated heat flux generates pressure waves in the sample fluid. A first acoustic signal is generated  1306  in the first chamber. The first acoustic signal includes a third acoustic signal corresponding to the sample liquid and a fourth acoustic signal corresponding to the component in the sample fluid. 
     The modulated light beam is also transmitted to a reference fluid in a second chamber  1308 . In one embodiment, the reference fluid includes the insulation oil of the transformer system as the reference liquid. A second acoustic signal is generated  1310  in the second chamber and is representative of a pressure signal corresponding to the reference liquid. The first acoustic signal is transmitted to a first side of the pressure sensor disposed between the first chamber and the second chamber. The second acoustic signal is transmitted to a second side opposite to the first side of the pressure sensor. The third acoustic signal corresponding to the sample liquid fully neutralizes or substantially neutralizes the second acoustic signal corresponding to the reference liquid  1312 . The pressure sensor detects a difference  1314  between the first acoustic signal and the second acoustic signal. 
     The signal representative of the difference may include one of an optical signal, an electrical signal, and a pressure signal based on the type of the pressure sensor used. The signal representative of the difference is transmitted from the pressure sensor to a processor-based module  1316 . The processor based module measures an amplitude value of the signal representative of the difference. In one embodiment, the measured amplitude value may be a peak value of the signal representative of the difference. In one embodiment, the phase information of the signal representative of the difference may be used to determine the amplitude value. 
     The processor based module determines the component  1320  based on the range of wavelength of the modulated beam. In some embodiments, a look-up table having data corresponding to the gaseous components and their corresponding absorption spectral range may be used to determine the component. In one example, if the wavelength of the modulated light beam corresponds to a wavenumber in the range of 2200-2400 cm −1 , the processor based module determines the component as carbon dioxide. In another example, if the wavelength of the modulated light beam corresponds to a wavenumber in the range of 2900-3100 cm −1 , the component is detected as methane. In yet another example, if the wavelength of the modulated light beam corresponds to a wavenumber in the range of 3200-3400 cm −1 , the component is detected as acetylene. 
     In one embodiment, a concentration of the component may be determined  1322  based on the measured amplitude value, using a predetermined calibration chart. In one embodiment, the calibration chart may be determined based on a transfer function. In another embodiment, the calibration chart may be determined based on simulation results. The calibration chart is a look-up table having data entries of concentration values for a range of amplitude values corresponding to each of the gaseous components. 
     The exemplary systems and methods for inspection enable determination of a concentration of a component in a fluid using photo acoustic spectroscopy (PAS). The technique detects a small amplitude photo acoustic pressure wave corresponding to the component in a relatively large amplitude photo acoustic pressure wave corresponding to the sample liquid. In the case of electrical transformer systems, for example, the exemplary technique performs analysis of dissolved gas without extracting the gaseous components from the insulation oil. 
     It is to be understood that not necessarily all such objects or advantages described above may be achieved in accordance with any particular embodiment. Thus, for example, those skilled in the art will recognize that the systems and techniques described herein may be embodied or carried out in a manner that achieves or improves one advantage or group of advantages as taught herein without necessarily achieving other objects or advantages as may be taught or suggested herein. 
     While the technology has been described in detail in connection with only a limited number of embodiments, it should be readily understood that the invention are not limited to such disclosed embodiments. Rather, the technology can be modified to incorporate any number of variations, alterations, substitutions or equivalent arrangements not heretofore described, but which are commensurate with the spirit and scope of the claims. Additionally, while various embodiments of the technology have been described, it is to be understood that aspects of the inventions may include only some of the described embodiments. Accordingly, the inventions are not to be seen as limited by the foregoing description, but are only limited by the scope of the appended claims.