Patent Publication Number: US-2020301005-A1

Title: Array system for the characterization of an object

Description:
RELATED APPLICATIONS 
     The present application is a continuation of U.S. patent application Ser. No. 15/597,912, filed May 17, 2017, entitled “ARRAY SYSTEM FOR THE CHARACTERIZATION OF AN OBJECT”, the entire contents of which are incorporated by reference herein. 
    
    
     BACKGROUND 
     The horticultural industries produce a variety of crops including bedding plants, foliage plants, flowering plants, nursery stock, fruit plants, vegetable plants, and so forth. In vascular plants, a root is the organ of a plant that typically lies below the surface of the soil. Root growth and development may be central to an overall plant performance and growth. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The present disclosure described herein is illustrated by way of example and not by way of limitation in the accompanying figures. For simplicity and clarity of illustration, features illustrated in the figures are not necessarily drawn to scale. For example, the dimensions of some features may be exaggerated relative to other features for clarity. Further, where considered appropriate, reference labels have been repeated among the figures to indicate corresponding or analogous elements. 
         FIG. 1A  illustrates an antenna structure that includes a first antenna array, a second antenna array, a third antenna array, a fourth antenna array, and a fifth antenna array, according to one implementation. 
         FIG. 1B  illustrates an antenna structure that transmits a first signal from the first antenna array and a second signal from the third antenna array, according to one implementation. 
         FIG. 2  illustrates the antenna structure of  FIG. 1  placed around a plant to measure a root structure of the plant, according to one implementation. 
         FIG. 3  illustrates a flowchart of the method for generating a digital representation of an object, according to one implementation. 
     
    
    
     DETAILED DESCRIPTION 
     In the following description, various aspects of the illustrative implementations will be described using terms commonly employed by those skilled in the art to convey the substance of their work to others skilled in the art. However, it will be apparent to those skilled in the art that the present disclosure may be practiced with only some of the described aspects. For purposes of explanation, specific numbers, materials, and configurations are set forth in order to provide a thorough understanding of the illustrative implementations. However, it will be apparent to one skilled in the art that the present disclosure may be practiced without the specific details. In other instances, well-known features are omitted or simplified in order not to obscure the illustrative implementations. 
     Rhizometrics is the study, characterization, observation, and quantification of plant root growth and root systems. Root growth and root systems may indicate a health of a plant and a future performance of a plant to yield fruits or vegetables. A timing and development of the root structure may also indicate a response of the plant to different soils, fertilizers, moisture levels, air temperatures, and soil temperatures. 
     Conventionally, to examine the root growth and root systems of a plant, the plant may be dug up, the roots of the plant cleaned, and then the root structure may be analyzed. Digging up the plant may damage the roots or the body of the plant. Damage to the roots or the body of the plant may destroy or impede further development of the plant if the plant is returned to the soil. Additionally, manually digging up the plant, cleaning the roots, and analyzing the roots by manual inspection may be labor intensive and monotonous. 
     The present disclosure addresses the above-mentioned and other deficiencies by providing for an antenna structure that measures an absorption or reflection of signals by a root structure to determine the root growth and the root system of a plant. The antenna structure may include planar arrays that steer a direction of transmitted signals toward the root system of a plant. Receivers of the planar arrays may measure reflections or absorptions of the signals to determine the root system of the plant. An advantage of determining the root system of the plant using the antenna structure may be to non-invasively measure the root structure of the plant without removing the plant from the soil. 
       FIG. 1A  illustrates an antenna structure  100  that includes a first antenna array  102 , a second antenna array  104 , a third antenna array  106 , a fourth antenna array  108 , and a fifth antenna array  110 , according to one implementation. In one implementation, the first antenna array  102 , the second antenna array  104 , the third antenna array  106 , the fourth antenna array  108 , and the fifth antenna array  110  may be planar antenna arrays where the elements of each planar antenna array are on one plane. A planar antenna array may include a substrate, such as plastic or metal, with transmitters, receivers, and other components integrated into the substrate. A planar array may provide an aperture and may be used for directional beam control by varying a relative phase of the element of the planar array. In one example, a planar array may include antenna elements that may produce a steerable main lobe of radio frequency (RF) energy. In another implementation, the first antenna array  102 , the second antenna array  104 , the third antenna array  106 , the fourth antenna array  108 , and the fifth antenna array  110  may be wide-band antennas with antenna elements that do not interfere with each other when they are in relatively close proximity. In another implementation, the first antenna array  102 , the second antenna array  104 , the third antenna array  106 , the fourth antenna array  108 , and the fifth antenna array  110  may be steerable arrays with antenna elements that do not interfere with each other when they are in relatively close proximity. 
     The first antenna array  102  may be connected to the second antenna array  104  and the third antenna array  106 . The first antenna array  102  may be connected to the second antenna array  104  or the third antenna array  106  by a weld, a fastener, a hinge, adhesive, a rivet, and so forth. The first antenna array  102  may be connected to the second antenna array  104  or the third antenna array  106  at a defined angle. For example, the first antenna array  102  may be located on a first plane and the second antenna array  104  and the third antenna array  106  may be located on a second plane. The second plane may be at a defined angle relative to the first plane. For example, the second plane may be at approximately a 45-degree angle relative to the first plane. The second antenna array  104  and the third antenna array  106  may be coplanar and separated by a gap  125 . The gap  125  may provide space for a portion of an object, such as a stalk or body of a plant. 
     The second antenna array  104  may be connected to the fourth antenna array  108  at a defined angle. For example, the second antenna array  104  may be located on the second plane and the fourth antenna array  108  may be located on a third plane. The third plane may be at a defined angle relative to the second plane. For example, the third plane may be at approximately a 45-degree angle relative to the second plane. The second antenna array  104  may be connected to the fourth antenna array  108  by a weld, a fastener, a hinge, adhesive, a rivet, and so forth. 
     The third antenna array  106  may be connected to the fifth antenna array  110  at a defined angle. For example, the third antenna array  106  may be located on the second plane and the fifth antenna array  110  may be located on the third plane. The third antenna array  106  may be connected to the fifth antenna array  110  by a weld, a fastener, a hinge, adhesive, a rivet, and so forth. The number of antenna arrays is not intended to be limiting, and the antenna structure  100  may include different numbers of antenna arrays to provide different degrees of granularity for measuring the object  122 . In one example, as the number of the antenna arrays in the antenna structure  100  increases, the antenna structure  100  may make measurements from an increasing number of angles, which may increase the granularity of the measurements. In another example, the number of the antenna array in the antenna structure  100  may be based on the object the antenna structure  100  is being used to measure. For example, the antenna structure  100  may include the first antenna array  102 , the second antenna array  104 , the third antenna array  106 , the fourth antenna array  108 , and the fifth antenna array  110  to fit around a plant to measure a root structure of the plant, as discussed below. 
     The first antenna array  102 , the second antenna array  104 , the third antenna array  106 , the fourth antenna array  108 , and the fifth antenna array  110  may include transmitters and receivers. For example, the third antenna array  106  may include a transmitter  112  and a receiver  114 . The transmitter  112  may transmit a signal  116  with a defined amplitude and phase toward an object  122 . In one example, the signal  116  may have a frequency of 9.35 gigahertz (GHz). In another example, the signal  116  may have an amplitude between −40 dBm and −120 dBm and phase between 0 and 360 degrees. In one implementation, the object  122  may be a plant, such as a potted plant, a farm crop, or a plant in a garden. In another implementation, the object  122  may be a fossil that is part of an archeological dig, such as a dinosaur bone. 
     The object  122  may reflect at least a portion of the signal  118  back toward the third antenna array  106 . The third antenna array  106  may include a receiver  114  that may receive the reflection of the signal  116 . The antenna structure  100  may be coupled to an analog to digital converter (ADC)  118 . The ADC  118  may convert the signal  116  into a digital signal. For example, the ADC  118  may convert the signal  116  from a voltage or current measurement into a digital number proportional to the magnitude of the voltage or current. The ADC  118  may be coupled to a processing device  120 . The ADC  118  may send the digital signal to a processing device  120 . The processing device  120  may determine a phase or amplitude of the signal  116  when it was received at the receiver  114 . 
     In one example, the processing device  120  may determine a difference between the amplitude and phase of the signal  116  when it is transmitted by the transmitter  112  and the amplitude and phase of the signal  116  when it is reflected and received by the receiver  114 . In another example, the processing device  120  may determine a structure of the object  122  associated with the amplitude and phase of the signal  116 . For example, the object  122  may be a root structure of a plant. The processing device  120  may use the amplitude and phase of the signal  116  that is received at the receiver  114  to generate a digital representation of the root structure. For example, a range is generated by mixing a frequency modulated transmit signal with a return signal and then examining the low frequency mixing products to calculate range. The received signal strength intensity (RSSI) may be combined with the azimuth and elevation angle of the phased arrays to generate the location in a spherical reference frame with a radius equal the range information. Information may also be determined using heuristics and a topology to generate discrete components that may represent a root structure. 
     In one implementation, the processing device  120  may use a heuristic processing technique to generate the digital representation of the root structure. For example, the processing device  120  or a memory coupled to the processing device  120  may store one or more template digital representations of root structures for different plants. The processing device  120  may receive a message indicating a type of plant for the root structure being measured and may select the template digital representation of the root structure associated with that plant. The processing device  120  may then update or modify the template digital representation to incorporate or modify the template digital representation to include the root structure measurements taken by the antenna arrays. 
     In another implementation, the processing device  120  may use a pattern recognition processing technique to generate the digital representation of the root structure. For example, the processing device  120  may initially generate the digital representation of the root structure. The processing device  120  may then analyze the initial digital representation of the root structure for patterns in the root structure. When the initial digital representation of the root structure has missing or incomplete portions in the digital representation, the processing device  120  may fill in the missing or incomplete portions using pattern recognition. The processing device  120  may also use a template digital representation of the root structure and compare it to the initial digital representation to identify similar patterns in between the template digital representation and the initial digital representation. The processing device  120  may use the identified patterns to fill in the missing or incomplete portions of the digital representation of the root structure. 
     In one example, the processing device  120  may use the digital representation of the root structure to determine a number of root elements in the root structure, a size of the root elements in the root structure, a diameter of the individual root elements in the root structure, a physical topography of the root structure, a branching angle of the root elements, or a topological depth of the root elements. The number, size, diameter, and topology of the root elements may indicate the growth and development characteristics of the root elements. In another example, the processing device  120  may use the digital representation of the root structure to determine the root growth and root development of the root structure. The growth and development characteristics of the root elements may indicate a response of the plant to different soils, fertilizers, moisture levels, air temperatures, and soil temperatures. 
     The processing device  120  may use the digital representation of the root structure to calculate a root mass of the root structure. The root mass may indicate a biomass of the root structure, which may indicate a carbon sequestration of the root structure. 
     The signals transmitted by the transmitters of the first antenna array  102 , the second antenna array  104 , the third antenna array  106 , the fourth antenna array  108 , and the fifth antenna array  110  may be steerable. For example, the third antenna array  106  may include one or more antenna elements which produce a main lobe of radio frequency (RF) energy. The main lobe of the RF energy (also referred to as a beam) may be steerable to transmit signals toward the object  122 , such as the root structure of the plant, from different positions and angles and then receive the reflected signals for the different positions and angles. In one example, the antenna arrays may change a direction or radiation pattern of the beam transmitted by the transmitters of the antenna arrays. In one implementation, the antenna arrays may steer the beam by switching elements of the antenna arrays on or off. In another implementation, the antenna arrays may steer the RF energy by changing the relative phases of the RF signals driving the elements of the antenna arrays. 
     The processing device  120  may electronically steer the RF energy transmitted by an antenna array to probe or examine different portions of the object  122  or the area approximate the object  122 . For example, the processing device  120  may steer the RF energy of an antenna array to sweep a defined area to determine the root structure of a plant within the defined area. In this example, the processing device  120  may use the antenna array to take multiple measurements as it steers the RF energy and then aggregates the multiple measurements to generate an aggregate digital representation of the root structure. In another example, the processing device  120  may iteratively steer a transmission of a sequence of signals from the third antenna array  106  at toward different portions of the object  122 . The processing device  120  may receive reflections of the sequence of signals off of the different portions of the object  122  and determine a digital representation of the object  122  by aggregating the reflections of the sequence of signals. 
     The processing device  120  may aggregate the signals received by the receivers of the first antenna array  102 , the second antenna array  104 , the third antenna array  106 , the fourth antenna array  108 , and the fifth antenna array  110  to generate the digital representation of the root structure. In one implementation, the first antenna array  102  may send and receive signals from the different positions and angles. For example, the first antenna array  102  may steer a transmitted signal to sweep across a defined area to take an aggregated set of measurements that approximately covers the defined area. The second antenna array  104 , the third antenna array  106 , the fourth antenna array  108 , and the fifth antenna array  110  may also transmit signals at different positions and angles to sweep defined areas to take an aggregated set of measurements that approximately covers the defined areas. The positions and angles of the signals transmitted by the first antenna array  102 , the second antenna array  104 , the third antenna array  106 , the fourth antenna array  108 , and the fifth antenna array  110  may be known or predefined values stored at the processor. The processor may aggregate the various sets of measurements to generate the digital representation of the root structure. 
     In one implementation, other particles and objects may interfere with measuring the object  122 . For example, when the object  122  is a root system, different characteristics of the soil where the roots are located may interfere with the measurement of the roots. To calibrate for the different soil characteristics, the antenna structure  100  may include a probe  124 . The probe  124  may be an RF target inserted into a medium, such a ground, underneath. In one implementation, the probe  124  may be manually inserted and removed from the ground by an individual. In another implementation, the probe  124  may be automatically extended and retracted by the antenna structure  100 . For example, the processing device  120  may engage a mechanical actuator to extend or retract the probe  124 . 
     The probe  124  may have known absorption and reflective values for signals transmitted at the probe  124  by the transmitters of the first antenna array  102 , the second antenna array  104 , the third antenna array  106 , the fourth antenna array  108 , and the fifth antenna array  110 . For example, the probe  124  may be a material with a known absorption and reflection properties for the transmitted signal, such as a ceramic material. The processing device  120  may transmit one or more calibration signals from the transmitters of the first antenna array  102 , the second antenna array  104 , the third antenna array  106 , the fourth antenna array  108 , and the fifth antenna array  110  toward the probe  124 . The processing device  120  may then measure the amplitude and phase of the signal that is reflected by the probe  124 . The processing device  120  may then compare an expected amplitude and phase (also referred to herein as an expected reflection) of the signal when there is no interference or noise with the actual amplitude and phase of the signal when it is transmitted through the soil to the probe  124  to determine the interference or noise caused by the soil and obtain calibration measurement. The interference by the soil may include permittivity and attenuation characteristics of the soil. For example, the permittivity of the soil may enable more or less water to be retained in the soil. As the amount of water retained in the soil increase, the interference to the signal also increases. 
     The processing device  120  may then calibrate the signals reflected by the object  122  to account for the interference caused by the soil using the calibration measurement. For example, when the first antenna array  102 , the second antenna array  104 , the third antenna array  106 , the fourth antenna array  108 , or the fifth antenna array  110  transmits a signal toward the object  122  and receives a reflected signal, the processing device  120  may determine an increase or decrease in the amplitude and phase of the signal caused by the soil and filter out that interference in the signal. 
     To determine the digital representation of the root structure, the processing device  120  may use a wavelet transformation in order to produce a geometric representation of the root structure in a digital format. A wavelet is a function to divide a signal into different components, such as amplitude and phase components. The wavelet transformation is a function that uses the wavelet in digital signal processing to generate a digital representation of the wavelets. The removing of the interference from the signal may increase a range, resolution, and accuracy of the digital representation of the amplitude and phase of the signals. 
       FIG. 1B  illustrates an antenna structure  100  that transmits a first signal  130  from the first antenna array  102  and a second signal  116  from the third antenna array  106 , according to one implementation. Some of the features in  FIG. 1B  are the same or similar to the some of the features in  FIG. 1A  as noted by same reference numbers, unless expressly described otherwise. 
     As discussed above, the antenna structure  100  may include the first antenna array  102 , the second antenna array  104 , the third antenna array  106 , the fourth antenna array  108 , and the fifth antenna array  110 . The first antenna array  102  may include a transmitter  126  and a receiver  128 . The transmitter  126  may transmit a first signal  130  toward the object  122 . The receiver  128  may receive a reflection of the first signal  130  off of the object  122 . The third antenna array  106  may include the transmitter  112  and the receiver  114 . The transmitter  112  may transmit the second signal  116  toward the object  122 . The receiver  114  may receive a reflection of the second signal  116  off of the object  122 . The ADC  118  may convert the first signal  130  and the second signal  116  into digital values and send the digital values to the processing device  120 . The processing device  120  may aggregate the digital values and generate a digital representation of the object  122 , as discussed above. 
     Aggregating the digital values of multiple signals from the first antenna array  102 , the second antenna array  104 , the third antenna array  106 , the fourth antenna array  108 , and the fifth antenna array  110  may increase an accuracy of the digital representation of the object  122  because the first antenna array  102 , the second antenna array  104 , the third antenna array  106 , the fourth antenna array  108 , and the fifth antenna array  110  transmit signals from different locations and at different angles. The different location and angles of transmission of the signals may provide unique signal information from the signals that the processing device  120  may aggregate to get a complete representation of the object  122 . For example, the first antenna array  102  may transmit a first signal toward the portion of the object  122  at a first angle of transmission. The second antenna array  104  may transmit a second signal toward the portion of the object  122  at a second angle of transmission. The third antenna array  106  may transmit a third signal toward the portion of the object  122  at a third angle of transmission. The fourth antenna array  108  may transmit a fourth signal toward the portion of the object  122  at a fourth angle of transmission. The fifth antenna array  110  may transmit a fifth signal toward the portion of the object  122  at a fifth angle of transmission. 
     The processing device  120  may also use the multiple signals to correct errors in the digital representation of the object  122 . For example, an interfering object  132  may be located approximate to the object  122 . The interfering object  132  may be a rock, water, and so forth. The interfering object  132  may at least partially interfere with the second signal  116  reflecting off the object  122 . The interference from the object  132  may interfere with the second signal  116  and cause the amplitude and the phase of the second signal  116  to be incorrect. The incorrect amplitude and phase of the reflected second signal  116  may introduce errors into a digital representation of the object  122 . The first signal  130  may be transmitted by the first antenna array  102  from a different angle and a different location. The first signal may not encounter the interfering object  132  and may not have interference from the interfering object  122  in the amplitude and phase of the reflected first signal  130 . When the processing device  120  receives the digital values associated with the first signal  130  and the second signal  116 , the processor may determine that the digital values for the first signal  130  differ from the digital values of the second signal  116  by a threshold amount. The difference in the digital values may indicate that there is an interfering object  132  that is causing the difference. 
     In one implementation, the processing device  120  may filter out the digital values for the second signal  116  when the digital values are outside an expected range. In another implementation, when the processing device  120  receives digital values from multiple antenna arrays, the processing device  120  may compare the digital values to determine if one or more of the digital values are an outlier. When one of the digital values is an outlier, the processing device  120  may remove the digital value from the aggregated digital values used to generate the digital representation of the object  122 . For example, each of the first antenna array  102 , the second antenna array  104 , the third antenna array  106 , the fourth antenna array  108 , and the fifth antenna array  110  may send signals toward the object  122  and receive reflected signals. The processing device  120  may receive digital values associated with each of the reflected signals. When the digital values from the second antenna array  104 , the third antenna array  106 , the fourth antenna array  108 , and the fifth antenna array  110  are within a threshold range and the digital value from the first antenna array  102  is outside the threshold range, the processing device  120  may remove the digital value for the first antenna array  102  from the aggregate digital values from the first antenna array  102 , the second antenna array  104 , the third antenna array  106 , the fourth antenna array  108 , and the fifth antenna array  110 . 
       FIG. 2  illustrates the antenna structure  100  of  FIG. 1  located around a plant  200  to measure a root structure  202  of the plant  200 , according to one implementation. Some of the features in  FIG. 2  are the same or similar to the some of the features in  FIG. 1A  as noted by same reference numbers, unless expressly described otherwise. 
     The antenna structure  100  may be placed around the plant  200  so that the processing device  120  may measure the root structure  202  of the plant  200  using the antenna structure  100 , as discussed above. To place the antenna structure  100  around the plant  200 , the plant  200  may be placed within the gap  125  in the antenna structure  100 . In one example, the plant  200  may be a potted plant. In another example, the plant  200  may be a farm crop or a plant in a garden. 
     When the plant  200  is located within the gap  125 , the antenna structure  100  may be arranged around the plant to transmit signals from the first antenna array  102 , the second antenna array  104 , the third antenna array  106 , the fourth antenna array  108 , and the fifth antenna array  110  toward the root structure  202 . The processing device  120  may use digital values from the reflections of the signals to generate a digital representation of the root structure  202 , as discussed above. 
     The processing device  120  may use the antenna structure  100  to monitor the root structure  202  periodically, on a regular basis, or continuously. For example, the processing device  120  may use the antenna structure  100  to take a measurement of the root structure  202  and generate a digital representation of the root structure  202  on a daily basis. The processing device  120  may monitor the development and growth of the root elements of the root structure to determine a developmental progress of the plant  200  over a period of time. The developmental progress of the plant  200  may be monitored over a propagation stage of the plant  200 , a production state of the plant  200 , and/or a post-production state of the plant  200 . The developmental progress of the plant  200  may indicate anchoring of the root structure  202 , a support of the root structure  202 , and water and nutrient uptake of the root structure  202 . In one example, the root elements may be 1.9 millimeters (mm) in diameter and 50 mm long. 
       FIG. 3  illustrates a flowchart of the method  300  for generating a digital representation of an object, according to one implementation. The method  300  may at least partially be performed by processing logic that includes hardware (e.g., circuitry, dedicated logic, programmable logic, microcode, etc.), software (e.g., instructions executed by a processing device), firmware or a combination thereof. In one embodiment, the method  300  may be performed by all or part of the processing device  120  of  FIGS. 1A and 1B . 
     Referring to  FIG. 3 , the method  300  begins with a processor receiving a request to determine a structure of an object (block  302 ). For example, the processor may receive a request to determine a root structure of a plant. The method may include extending a probe from an antenna structure (block  304 ). The method may include transmitting a first signal from an antenna array of the antenna structure through a material toward the probe (block  306 ). For example, the antenna array may transmit the first signal through dirt toward the probe. The method may include measuring a reflection of the first signal off of the probe to obtain a first reflected signal (block  308 ). 
     The method may include determining a calibration measurement in view of the first reflected signal (block  310 ). For example, the probe may be a material with known absorption and reflection properties. The processor may transmit one or more signals from the transmitters of the antenna array. The processor may then measure an amplitude and phase of the signal that is reflected by the probe. The processor may then compare an expected amplitude and phase of the signal when there is no interference with the actual amplitude and phase of the signal when it is transmitted through the soil to the probe to determine the interference caused by the soil. 
     The method may include retracting the probe after the signal has been reflected by the probe (block  312 ). The method may include the processor transmitting a second signal through the material toward the object (block  314 ). The method may include the processor measuring a reflection of the second signal off of the object to obtain a second reflected signal (block  316 ). The method may include the processor filtering out interference in the second reflected signal using the calibration measurement (block  318 ). The method may include determining a structure of the object using the second reflected signal (block  320 ). In one example, the processor may use a heuristic to determine a structure of the object, as discussed above. 
     Various operations are described as multiple discrete operations, in turn, in a manner that is most helpful in understanding the present disclosure, however, the order of description may not be construed to imply that these operations are necessarily order dependent. In particular, these operations need not be performed in the order of presentation. 
     The terms “over,” “above” “under,” “between,” and “on” as used herein refer to a relative position of one material layer or component with respect to other layers or components. For example, one layer disposed above or over or under another layer may be directly in contact with the other layer or may have one or more intervening layers. Moreover, one layer disposed between two layers may be directly in contact with the two layers or may have one or more intervening layers. In contrast, a first layer “on” a second layer is in direct contact with that second layer. Similarly, unless explicitly stated otherwise, one feature disposed between two features may be in direct contact with the adjacent features or may have one or more intervening layers. The words “example” or “exemplary” are used herein to mean serving as an example, instance, or illustration. Any aspect or design described herein as “example” or “exemplary” is not necessarily to be construed as preferred or advantageous over other aspects or designs. Rather, use of the words “example” or “exemplary” is intended to present concepts in a concrete fashion. As used in this application, the term “or” is intended to mean an inclusive “or” rather than an exclusive “or.” That is, unless specified otherwise, or clear from context, “X includes A or B” is intended to mean any of the natural inclusive permutations. That is, if X includes A; X includes B; or X includes both A and B, then “X includes A or B” is satisfied under any of the foregoing instances. In addition, the articles “a” and “an” as used in this application and the appended claims may generally be construed to mean “one or more” unless specified otherwise or clear from context to be directed to a singular form. Moreover, use of the term “an implementation” or “one implementation” throughout is not intended to mean the same implementation or implementation unless described as such. The terms “first,” “second,” “third,” “fourth,” etc. as used herein are meant as labels to distinguish among different elements and may not necessarily have an ordinal meaning according to their numerical designation. 
     It will be appreciated that variants of the above-disclosed and other features and functions, or alternatives thereof, may be combined into many other different systems of applications. Various presently unforeseen or unanticipated alternatives, modifications, variations, or improvements therein may be subsequently made by those skilled in the art which are also intended to be encompassed by the following claims.