Abstract:
System and methods for servicing and monitoring shock struts are provided. A method for servicing a shock strut may include calculating a first fluid level; generating a first datum corresponding to the first fluid level; moving fluid into the shock strut in accordance with the first datum; calculating a second fluid level; generating a second datum corresponding to the second fluid level; and storing a final fluid level.

Description:
FIELD 
       [0001]    The present disclosure relates to landing gear, and more particularly, to systems and methods for increasing the serviceability of shock struts within landing gear. 
       BACKGROUND 
       [0002]    Conventionally, various types of aircraft utilize shock strut assemblies to assist in reducing and managing energy transmitted from landing gear to the structure of an aircraft to which the landing gear is attached. Such shock strut assemblies often feature a piston that compresses a fluid within a sealed chamber. The fluid typically includes a gas segment and a liquid segment. Performance of the shock strut assembly may degrade over time. Such degradation can cause damage to other components of the aircraft, including bearings of the landing gear assembly. With typical single stage shock struts, the aircraft is lifted above the ground so that the shock strut can be in the fully extended position for servicing. Then, the shock strut may be cycled multiple times in attempt to fully remove any trapped gas internal to the shock strut during servicing. This can be time consuming and costly. 
       SUMMARY 
       [0003]    A process for servicing a shock strut is provided. A process for servicing a shock strut may include: calculating a first fluid level; generating a first datum corresponding to the first fluid level; moving fluid into the shock strut in accordance with the first datum; calculating a second fluid level; generating a second datum corresponding to the second fluid level; and storing a final fluid level. 
         [0004]    In various embodiments, the fluid may comprise at least one of oil or gas. The calculating the first fluid level may be performed by a controller. The generating the first datum may be performed by a controller. The calculating the second fluid level may be performed by a controller. The generating the second datum may be performed by a controller. The storing the final fluid level may be performed by a controller. The calculating the second fluid level may include using at least one of an initial fluid pressure, an initial fluid temperature, an initial shock strut stroke position, an updated fluid pressure, an updated fluid temperature, and an updated shock strut stroke position. The generating the first datum may be in response to at least one of a fluid volume loss or a fluid number of moles loss being more than or equal to a threshold value. The process for servicing the shock strut may allow for independent servicing of a gas in the shock strut and an oil in the shock strut. The storing the final fluid level may be in response to the second datum. The final fluid level may be calculated using at least one of a desired fluid level, the second fluid level, and a fluid level loss. A landing gear of an aircraft on which the shock strut may be mounted may be supported by at least one of a fixed surface or a jack during the process for servicing the shock strut. 
         [0005]    A shock strut servicing assistance system may comprise: a controller including a display; and a tangible, non-transitory memory configured to communicate with the controller. The tangible, non-transitory memory may have instructions stored thereon that, in response to execution by the controller, cause the controller to perform operations comprising: calculating, by the controller, a first fluid level; generating, by the controller, a first datum corresponding to the first fluid level; receiving, by the shock strut, a fluid in response to the first datum; calculating, by the controller, a second fluid level; generating, by the controller, a second datum; and storing, by the controller, a final fluid level. 
         [0006]    In various embodiments, the controller may be in electronic communication with a shock strut servicing monitoring system. An indication may be displayed on the display in response to at least one of the first datum or the second datum. The second datum may be generated in response to the second fluid level being greater than a threshold value. The first fluid level and the second fluid level may correspond to at least one of a volume of a fluid added to a shock strut during service or a number of moles of the fluid added to the shock strut during service. The fluid may comprise at least one of oil or gas. 
         [0007]    A method for monitoring a shock strut may include: adjusting, by a controller, at least one of an oil volume and a gas pressure; detecting, by the controller, at least one of an oil volume loss and a gas number of moles loss; and generating, by the controller, a signal corresponding to the at least one of the oil volume loss and the gas number of moles loss. 
         [0008]    In various embodiments, the controller may receive the at least one of the oil volume and the gas pressure from a shock strut servicing monitoring system (SSSMS). The adjusting may comprise adjusting to a normalized value. The detecting may include comparison of a desired value with an adjusted value of the at least one of the oil volume and the gas pressure. The signal may be generated by comparing the at least one of the oil volume loss and the gas number of moles loss with a range of threshold values, the range including from 1 to 100 threshold values. 
         [0009]    The foregoing features and elements may be combined in various combinations without exclusivity, unless expressly indicated otherwise. These features and elements as well as the operation thereof will become more apparent in light of the following description and the accompanying drawings. It should be understood, however, the following description and drawings are intended to be exemplary in nature and non-limiting. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0010]    The subject matter of the present disclosure is particularly pointed out and distinctly claimed in the concluding portion of the specification. A more complete understanding of the present disclosure, however, may best be obtained by referring to the detailed description and claims when considered in connection with the drawing figures, wherein like numerals denote like elements. 
           [0011]      FIG. 1  illustrates a single stage shock strut for use in landing gear of an aircraft, in accordance with various embodiments; 
           [0012]      FIG. 2  illustrates a loss detection process, in accordance with various embodiments; 
           [0013]      FIG. 3  illustrates an exemplary display in display mode, in accordance with various embodiments; 
           [0014]      FIG. 4  illustrates an exemplary display in servicing mode, in accordance with various embodiments; 
           [0015]      FIG. 5  illustrates an oil level adjustment process, in accordance with various embodiments; 
           [0016]      FIG. 6  illustrates a gas level adjustment process, in accordance with various embodiments; 
           [0017]      FIG. 7  illustrates a method for monitoring a shock strut, in accordance with various embodiments; 
           [0018]      FIG. 8  illustrates a process for servicing oil volume within a shock strut, in accordance with various embodiments; and 
           [0019]      FIG. 9  illustrates a process for servicing gas pressure within a shock strut, in accordance with various embodiments. 
       
    
    
     DETAILED DESCRIPTION 
       [0020]    The detailed description of exemplary embodiments herein makes reference to the accompanying drawings, which show exemplary embodiments by way of illustration and their best mode. While these exemplary embodiments are described in sufficient detail to enable those skilled in the art to practice the disclosure, it should be understood that other embodiments may be realized and that logical, chemical and mechanical changes may be made without departing from the spirit and scope of the disclosure. Thus, the detailed description herein is presented for purposes of illustration only and not of limitation. For example, the steps recited in any of the method or process descriptions may be executed in any order and are not necessarily limited to the order presented. Furthermore, any reference to singular includes plural embodiments, and any reference to more than one component or step may include a singular embodiment or step. Also, any reference to attached, fixed, connected or the like may include permanent, removable, temporary, partial, full and/or any other possible attachment option. Additionally, any reference to without contact (or similar phrases) may also include reduced contact or minimal contact. 
         [0021]    System program instructions and/or controller instructions may be loaded onto a non-transitory, tangible computer-readable medium having instructions stored thereon that, in response to execution by a controller, cause the controller to perform various operations. The term “non-transitory” is to be understood to remove only propagating transitory signals per se from the claim scope and does not relinquish rights to all standard computer-readable media that are not only propagating transitory signals per se. Stated another way, the meaning of the term “non-transitory computer-readable medium” and “non-transitory computer-readable storage medium” should be construed to exclude only those types of transitory computer-readable media which were found in In Re Nuijten to fall outside the scope of patentable subject matter under 35 U.S.C. §101. 
         [0022]    Aircraft landing gear systems in accordance with the present disclosure may comprise a shock strut. A shock strut may comprise various fluids such as oil and gas. Performance of the shock strut may be evaluated by monitoring aspects of the shock strut, including gas temperature, gas pressure, oil pressure, and stroke of the shock strut at various points during operation of the aircraft. Stroke may refer to a shock strut piston position. A servicing assistance system may be used in addition to a monitoring system to calculate oil loss and gas loss within a shock strut. Thus, oil and/or gas may be added to the shock strut during a maintenance process where the monitoring system indicates to ground crew when the shock strut has been filled with the appropriate volume of oil and/or pressure of gas. In various embodiments, landing gear of an aircraft may remain on a fixed surface during the shock strut servicing process without the need to lift the aircraft. The fixed surface may be a runway, a shop floor, the earth, the ground, or the like, for example. In various embodiments, landing gear of an aircraft may be supported by a jack during the shock strut servicing process without the need to lift the aircraft. Hence, independent servicing of oil and gas in a shock strut may be performed and traditional shock strut servicing procedures may be greatly simplified. 
         [0023]    As used herein an oil level may refer to a volume of oil. As used herein a gas level may refer to the number of moles of gas. 
         [0024]    The following nomenclature corresponds to various equations and parameters described in the present disclosure: 
         [0025]    Tunable Parameters: 
         [0026]    A: Piston area 
         [0027]    P gas,nom : Shock strut inflation pressure at 20° C. in the fully extended position 
         [0028]    V tot,in-air : Shock strut internal volume in the fully extended position 
         [0029]    V oil,nom : Desired oil volume at 20° C. 
         [0030]    Internal Parameters: 
         [0031]    i: Counter 
         [0032]    P gas,m@20° C.,i : Computed pressure adjusted to 20° C. in iteration step ‘i’ 
         [0033]    P gas,m@Tgas : Computed pressure (SSSMS direct output) 
         [0034]    P gas,m@20° C. : Computed pressure adjusted to 20° C. (SSSMS adjusted output) 
         [0035]    R: Gas ideal constant 
         [0036]    V oil,m@20° C. : Computed oil volume adjusted to 20° C. (SSSMS adjusted output) 
         [0037]    V oil,m@Tgas : Computed oil volume (SSSMS direct output) 
         [0038]    dT: Integration step 
         [0039]    ΔV oil@20° C. : Oil volume loss adjusted to 20° C. 
         [0040]    Z: Gas compressibility index as a function of gas pressure and temperature 
         [0041]    V oil,0@Tgas,0 : Computed oil volume at the onset of servicing 
         [0042]    V gas,O@Tgas,0 : Computed gas volume at the onset of servicing 
         [0043]    ΔV oil-added@Tgas,0 : Computed oil volume added during servicing 
         [0044]    ΔV oil-added@20 C : Computed oil volume added during servicing adjusted to 20° C. 
         [0045]    n 0 : Number of moles of gas in the shock strut at the onset of servicing 
         [0046]    Δn gas,added : Number of moles of gas added to the shock strut during servicing 
         [0047]    Sensor Measurements: 
         [0048]    {circumflex over (T)} gas : Gas temperature 
         [0049]    {circumflex over (T)} gas,0 : Gas temperature at the onset of servicing 
         [0050]    Ŝ: Shock strut stroke 
         [0051]    Ŝ 0 : Shock strut stroke at the onset of servicing 
         [0052]    {circumflex over (P)} gas : Shock strut pressure 
         [0053]    {circumflex over (P)} gas,0 : Shock strut pressure at the onset of servicing 
         [0054]    Accordingly, with reference to  FIG. 1 , a landing gear assembly  100  is illustrated. In various embodiments, landing gear assembly  100  comprises a shock strut  104 . Shock strut  104  may be mechanically coupled to a wheel assembly  106 . In various embodiments, shock strut  104  may be configured to absorb and dampen forces transmitted by wheel assembly  106  to an aircraft. 
         [0055]    Shock strut  104  may comprise, for example, a piston  102  and a cylinder  108 . Cylinder  108  may be configured to receive piston  102  in a manner that allows the two components to telescope together and absorb and dampen forces transmitted by wheel assembly  106 . 
         [0056]    In various embodiments, a liquid, such as a hydraulic fluid or oil, is located within cylinder  108 . Cylinder  108  and piston  102  may, for example, be configured to seal such that liquid contained within cylinder  108  is prevented from leaking as piston  102  translates relative to cylinder  108 . Further, cylinder  108  may be configured to contain a gas such as nitrogen gas or air. Shock strut  104  may comprise a proximal end and a distal end, wherein the distal end is opposite the proximal end, the distal end being the end of the shock strut closest to a wheel or wheel assembly of a vehicle, such as wheel assembly  106 , for example. The air may be positioned above the oil (referred to as an “air-over-oil” arrangement) or vice versa, where the term “above” in this context means in the direction of the proximal end of the shock strut. Similarly, cylinder  108  and piston  102  may be sealed such that gas is prevented from leaking as piston  102  moves relative to cylinder  108 . As such, shock strut  104  may comprise a pressurized environment within cylinder  108 . 
         [0057]    Shock strut  104  may further comprise, for example, a gas pressure sensor  110 . In various embodiments, gas pressure sensor  110  may be capable of measuring the pressure of the gas within shock strut  104  at a desired time. For example, gas pressure sensor  110  may measure the gas pressure within shock strut  104  before, during, or after take-off, or at any point during the duty cycle of shock strut  104 . 
         [0058]    In various embodiments, shock strut  104  may further comprise, for example, a gas temperature sensor  112 . Gas temperature sensor  112  may be capable of measuring the temperature of the gas within shock strut  104  at any point during the duty cycle of shock strut  104 . 
         [0059]    Similarly, shock strut  104  may comprise an oil pressure sensor  114 . In various embodiments, oil pressure sensor  114  may be capable of measuring the pressure of the oil within shock strut  104  at a desired time. For example, oil pressure sensor  114  may measure the oil pressure within shock strut  104  at any point during the duty cycle of shock strut  104 . 
         [0060]    In various embodiments, shock strut  104  may include various other sensors. Shock strut  104  may include an oil temperature sensor. An oil temperature sensor may be used to measure the temperature of oil inside of shock strut  104 . An oil temperature sensor may aide in determining the pressure of oil inside of shock strut  104 . 
         [0061]    Shock strut  104  may also comprise a position sensor  116 . In various embodiments, position sensor  116  may be capable of measuring the position of piston  102  relative to cylinder  108 , which is conventionally referred to as the stroke of shock strut  104  at a desired time. Position sensor  116  may be configured to measure the position indirectly, for example, by measuring the orientation of one or more shock strut torque links  118  (or other components). For example, position sensor  116  may measure the stroke of shock strut  104  at any point during the duty cycle of shock strut  104 . 
         [0062]    With reference to  FIG. 2 , loss detection process  200  is illustrated, in accordance with various embodiments. In various embodiments, loss detection process  200  may comprise system program instructions and/or controller instructions. Loss detection process  200  may be located on handheld device  302  of  FIG. 3 . However, it is contemplated that loss detection process  200  may be located on any controller located on for example, an aircraft or other vehicle. In various embodiments, loss detection process  200  may include normalizing process  206 , quantifying process  210 , and display process  214 . In various embodiments, loss detection process  200  may include shock strut servicing monitoring system (SSSMS)  202 . However, in various embodiments, loss detection process  200  and SSSMS  202  may comprise two separate processes, wherein loss detection process  200  receives oil volume  204  and/or gas pressure  205  from SSSMS  202  as one or more inputs. 
         [0063]    With further reference to  FIG. 7 , a method  700  for monitoring a shock strut is provided. In various embodiments, shock strut servicing monitoring system (SSSMS)  202  may quantify oil volume  204  and gas pressure  205 . Normalizing process  206  may receive oil volume  204  and gas pressure  205  as one or more inputs from SSSMS  202 . Normalizing process  206  may use oil volume  204  and gas pressure  205  to calculate normalized oil volume  208  and normalized gas pressure  209  (see step  701 ). Normalizing process  206  may use equation 1 and equation 2, below, to calculate normalized oil volume  208  and normalized gas pressure  209 . As illustrated in  FIG. 2 , oil volume  204  and gas pressure  205  are adjusted to volume and pressure corresponding to twenty degrees Celsius, respectively. However, it is contemplated that oil volume  204  and gas pressure  205  may be adjusted to any normalized value. 
         [0000]    
       
         
           
             
               
                 
                   
                     
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                                                         . 
                                                       
                                                     
                                                   
                                                   ) 
                                                 
                                               
                                               
                                                 Z 
                                                  
                                                 
                                                   ( 
                                                   
                                                     
                                                       P 
                                                       
                                                         gas 
                                                         , 
                                                         
                                                           m 
                                                           @ 
                                                           
                                                             
                                                             T 
                                                             ^ 
                                                             
                                                             gas 
                                                           
                                                         
                                                       
                                                     
                                                     , 
                                                     
                                                       
                                                         T 
                                                         ^ 
                                                       
                                                       gas 
                                                     
                                                   
                                                   ) 
                                                 
                                               
                                             
                                           
                                           - 
                                           14.7 
                                         
                                       
                                     
                                   
                                 
                               
                             
                              
                             
                               
 
                             
                              
                             End 
                           
                         
                       
                     
                   
                 
               
               
                 
                   Eq 
                   . 
                   
                       
                   
                    
                   
                     ( 
                     1 
                     ) 
                   
                 
               
             
             
               
                 
                   
                     P 
                     
                       gas 
                       , 
                       
                         
                           m 
                           @ 
                           20 
                         
                          
                         ° 
                          
                         
                             
                         
                          
                         
                           C 
                           . 
                         
                       
                     
                   
                   ≃ 
                   
                     P 
                     
                       gas 
                       , 
                       
                         
                           m 
                           @ 
                           20 
                         
                          
                         ° 
                          
                         
                             
                         
                          
                         
                           C 
                           . 
                         
                       
                       , 
                       
                         i 
                         + 
                         1 
                       
                     
                   
                 
               
               
                 
                   Eq 
                   . 
                   
                       
                   
                    
                   
                     ( 
                     2 
                     ) 
                   
                 
               
             
           
         
       
     
         [0064]    In various embodiments, quantifying process  210  may receive normalized oil volume  208  and normalized gas pressure  209  as one or more inputs. Quantifying process  210  may receive desired oil volume  230  and desired gas pressure  231  as one or more inputs. Desired oil volume  230  and desired gas pressure  231  may refer to a desired oil volume and desired gas pressure, respectfully. Thus, desired gas pressure  231  may correspond with a desired number of moles of gas. Quantifying process  210  may use equation 3 and equation 4 to calculate volume of oil loss (referred to herein as “oil loss”)  211  and number of moles of gas loss (referred to herein as “gas loss”)  212  (see step  702 ). 
         [0000]    
       
         
           
             
               
                 
                   
                     Δ 
                      
                     
                         
                     
                      
                     
                       V 
                       
                         
                           oil 
                           @ 
                           20 
                         
                          
                         ° 
                          
                         
                             
                         
                          
                         
                           C 
                           . 
                         
                       
                     
                   
                   = 
                   
                     
                       V 
                       
                         oil 
                         , 
                         nom 
                       
                     
                     - 
                     
                       V 
                       
                         oil 
                         , 
                         
                           
                             m 
                             @ 
                             20 
                           
                            
                           ° 
                            
                           
                               
                           
                            
                           
                             C 
                             . 
                           
                         
                       
                     
                   
                 
               
               
                 
                   Eq 
                   . 
                   
                       
                   
                    
                   
                     ( 
                     3 
                     ) 
                   
                 
               
             
             
               
                 
                   
                     Δ 
                      
                     
                         
                     
                      
                     
                       n 
                       gas 
                     
                   
                   = 
                   
                     
                       
                         
                           ( 
                           
                             
                               P 
                               
                                 gas 
                                 , 
                                 nom 
                               
                             
                             + 
                             14.7 
                           
                           ) 
                         
                         × 
                         
                           ( 
                           
                             
                               V 
                               tot 
                             
                             - 
                             
                               V 
                               
                                 oil 
                                 , 
                                 nom 
                               
                             
                           
                           ) 
                         
                       
                       
                         R 
                         × 
                         
                           ( 
                           
                             20 
                             + 
                             273 
                           
                           ) 
                         
                         × 
                         
                           Z 
                            
                           
                             ( 
                             
                               
                                 P 
                                 
                                   gas 
                                   , 
                                   nom 
                                 
                               
                               , 
                               
                                 20 
                                  
                                 ° 
                                  
                                 
                                     
                                 
                                  
                                 
                                   C 
                                   . 
                                 
                               
                             
                             ) 
                           
                         
                       
                     
                     - 
                     
                       
                         
                           ( 
                           
                             
                               P 
                               
                                 gas 
                                 , 
                                 
                                   
                                     m 
                                     @ 
                                     20 
                                   
                                    
                                   ° 
                                    
                                   
                                       
                                   
                                    
                                   
                                     C 
                                     . 
                                   
                                 
                               
                             
                             + 
                             14.7 
                           
                           ) 
                         
                         × 
                         
                           ( 
                           
                             
                               V 
                               tot 
                             
                             - 
                             
                               V 
                               
                                 oil 
                                 , 
                                 
                                   
                                     m 
                                     @ 
                                     20 
                                   
                                    
                                   ° 
                                    
                                   
                                       
                                   
                                    
                                   
                                     C 
                                     . 
                                   
                                 
                               
                             
                           
                           ) 
                         
                       
                       
                         R 
                         × 
                         
                           ( 
                           
                             20 
                             + 
                             273 
                           
                           ) 
                         
                         × 
                         
                           Z 
                            
                           
                             ( 
                             
                               
                                 P 
                                 
                                   gas 
                                   , 
                                   
                                     
                                       m 
                                       @ 
                                       20 
                                     
                                      
                                     ° 
                                      
                                     
                                         
                                     
                                      
                                     
                                       C 
                                       . 
                                     
                                   
                                 
                               
                               , 
                               
                                 20 
                                  
                                 ° 
                                  
                                 
                                     
                                 
                                  
                                 
                                   C 
                                   . 
                                 
                               
                             
                             ) 
                           
                         
                       
                     
                   
                 
               
               
                 
                   Eq 
                   . 
                   
                       
                   
                    
                   
                     ( 
                     4 
                     ) 
                   
                 
               
             
           
         
       
     
         [0065]    Oil loss  211  may comprise a value which represents the amount of oil that a shock strut has lost since its last servicing. Stated another way, oil loss  211  may comprise a value which represents the difference, in volume of oil, between a desired volume of oil and a current volume of oil in a shock strut. Gas loss  212  may comprise a value which represents the amount of gas that a shock strut has lost since its last servicing. Stated another way, gas loss  212  may comprise a value which represents the difference, in number of moles of gas, between a desired number of moles of gas and a current number of moles of gas in a shock strut. 
         [0066]    As illustrated in  FIG. 2 , display process  214  includes first oil decision  216 , second oil decision  220 , first gas decision  218 , second gas decision  222 , no action display process  224 , warning display process  226 , and service display process  228 . 
         [0067]    With reference to  FIG. 2  and  FIG. 3 , display process  214  may be used to generate a display such as, for example, display  300  provided in  FIG. 3 . First oil decision  216  may determine if oil loss  211  is above a second oil threshold. If oil loss  211  is above the second oil threshold, then service display process  228  may generate a warning signal such as, for example, “oil servicing is required” as illustrated by oil servicing signal  324  in  FIG. 3 , or the like (see step  703 ). If oil loss  211  is not above the second oil threshold, then second oil decision  220  may decide if oil loss  211  is above a first oil threshold. If oil loss  211  is above the first threshold, then service display process  226  may generate a warning signal such as, for example, “schedule for oil servicing”, or the like. If oil loss  211  is not above the first oil threshold, then no action display process  224  may be configured to not generate any signals, or may be configured to generate a signal indicating the that oil level is acceptable, or the like. 
         [0068]    First gas decision  218  may decide if gas loss  212  is above a second gas threshold. If gas loss  212  is above the second gas threshold, then service display process  228  may generate a warning signal such as, for example, “gas servicing is required”, or the like (see step  703 ). If gas loss  212  is not above the second gas threshold, then second gas decision  222  may decide if gas loss  212  is above a first gas threshold. If gas loss  212  is above the first gas threshold, then service display process  226  may generate a warning signal such as, for example, “schedule for gas servicing” as illustrated by gas service signal  322  in  FIG. 3 , or the like. If gas loss  212  is not above the first gas threshold, then no action display process  224  may be configured to not generate any signals, or may be configured to generate a signal indicating that the gas level is acceptable, or the like. 
         [0069]    In accordance with various embodiments, display process  214  may include one or more oil decisions, one or more gas decisions, and one or more display processes. Accordingly, display process  214  may use one or more threshold values to determine the type of display to generate. For example, many threshold values may be used to display a percentage representing the volume of oil and a percentage representing the volume of gas remaining in a shock strut, or the like. 
         [0070]    With reference to  FIG. 3 , display  300  is illustrated, in accordance with various embodiments. As illustrated in  FIG. 3 , display  300  located on a handheld device  302 . However, display  300  may be in any location such as, for example, an aircraft. With momentary reference to  FIG. 2 , all or part of loss detection process  200  may be located on handheld device  302 . Thus, handheld device  302  may include a computer readable medium. Handheld device  302  may comprise a controller. 
         [0071]    In various embodiments, display  300  may include various selectable tabs such as selectable tab  304 , selectable tab  306 , selectable tab  308 , selectable tab  310 , and selectable tab  312 . Selectable tab  310  may be selected to display parameters such as gas pressure  205 , gas temperature  314 , shock strut stroke  316 , gas loss  212 , gas service signal  322 , oil service signal  324 , and the like. With momentary reference to  FIG. 2 , in various embodiments, gas service signal  322  may be generated in response to a change in gas pressure located in a shock strut. Stated another way, gas service signal  322  may change in response to the value of oil loss  211  and/or gas loss  212  increasing above an oil and/or a gas threshold value. In various embodiments, oil service signal  324  may change in response to a change in oil volume located in a shock strut. Stated another way, oil service signal  324  may change in response to the value of oil loss  211  increasing above an oil threshold value. 
         [0072]    With respect to  FIG. 4 , elements with like element numbering, as depicted in  FIG. 3 , are intended to be the same and will not necessarily be repeated for the sake of clarity. 
         [0073]    With reference to  FIG. 4 , display  400  is illustrated, in accordance with various embodiments. Display  400  may be similar to display  300  of  FIG. 3 . Selectable tab  312  may be selected to display oil and/or gas servicing instructions. As illustrated in  FIG. 4 , display  400  includes a selectable oil adjustment start tab, a selectable oil adjustment finish tab, a selectable gas adjustment start tab, a selectable gas adjustment finish tab, and an indication signal  440 . However, any display may be used to implement the oil and/or gas level adjustment processes as described herein. In various embodiments, the oil level adjustment process may be followed by the gas level adjustment process. 
         [0074]    With further reference to  FIG. 8 , a method or process  800  for servicing oil volume within a shock strut is provided. With further reference to  FIG. 5 , selectable start tab  422  may be selected by an operator to start or initiate an oil level adjustment process  500 . In various embodiments, oil level adjustment process  500  may comprise system program instructions and/or controller instructions. Oil level adjustment process  500  may be located on handheld device  302 . However, it is contemplated that oil level adjustment process  500  may be located on a controller located on an aircraft or other vehicle. 
         [0075]    In various embodiments, oil level adjustment process  500  may include start decision  502 , oil addition calculator  520 , and comparator  530 . In various embodiments, oil level adjustment process  500  may include finish decision  522 , update process  524 , and memory  526 . In various embodiments, comparator  530  may include one or more IF logics. As illustrated in  FIG. 5 , comparator  530  includes first IF logic  534 , second IF logic  536 , third IF logic  538 , and fourth IF logic  540 . 
         [0076]    Start decision  502  may determine if an operator has indicated to start an oil level adjustment process. For example, an operator may select selectable start tab  422  and in response, start decision  502  may indicate to start oil level adjustment process  500 . In various embodiments, oil addition calculator  520  may quantify the volume of oil added to a shock strut in response to start decision  502  being true. Oil addition calculator  520  may receive initial gas pressure  518 , initial gas temperature  516 , and initial shock strut stroke  514  from initial parameter retriever  506 . In various embodiments, initial parameter retriever  506  may acquire initial gas pressure  518 , initial gas temperature  516 , and initial shock strut stroke  514  from a shock strut servicing monitoring system such as SSSMS  202  (see  FIG. 2 ). However, initial parameter retriever  506  may acquire initial gas pressure  518 , initial gas temperature  516 , and initial shock strut stroke  514  from any suitable location. Initial parameter retriever  506  may be configured to acquire initial gas pressure  518 , initial gas temperature  516 , and initial shock strut stroke  514 . Initial gas pressure  518 , initial gas temperature  516 , and initial shock strut stroke  514  may be the gas pressure, gas temperature, and shock strut stroke at the onset of the oil level adjustment process  500 , respectively. Oil addition calculator  520  may receive updated gas pressure  512 , updated gas temperature  510 , and updated shock strut stroke  508  from updating parameter retriever  504 . Updating parameter retriever may acquire updated gas pressure  512 , updated gas temperature  510 , and updated shock strut stroke  508  at a pre-determined rate, such as 10 Hz, for example. Updated gas pressure  512 , updated gas temperature  510 , and updated shock strut stroke  508  may be the gas pressure, gas temperature, and shock strut stroke, respectively, as measured by the shock strut sensors during the oil level adjustment process  500 . 
         [0077]    Oil addition calculator  520  may use equation 5 through equation 9 to calculate the volume of added oil (also referred to herein as a first fluid level)  521  to a shock strut (see step  801 ). Volume of added oil  521  may be the equivalent volume of oil added to a shock strut at a predetermined temperature such as twenty degrees Celsius, for example. 
         [0000]    
       
         
           
             
               
                 
                   
                     V 
                     
                       oil 
                       , 
                       
                         0 
                         @ 
                         
                           
                             T 
                             ^ 
                           
                           
                             gas 
                             , 
                             0 
                           
                         
                       
                     
                   
                   = 
                   
                     
                       ( 
                       
                         
                           V 
                           
                             oil 
                             , 
                             nom 
                           
                         
                         - 
                         
                           Δ 
                            
                           
                               
                           
                            
                           
                             V 
                             
                               
                                 oil 
                                 @ 
                                 20 
                               
                                
                               ° 
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                                
                               
                                 C 
                                 . 
                               
                             
                           
                         
                       
                       ) 
                     
                      
                     
                       
                         ( 
                         
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                           + 
                           
                             α 
                             × 
                             dT 
                             × 
                             
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                                
                               
                                 ( 
                                 
                                   
                                     
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                                       ^ 
                                     
                                     
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                                       , 
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                                   - 
                                   
                                     20 
                                      
                                     ° 
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                                      
                                     
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                                       . 
                                     
                                   
                                 
                                 ) 
                               
                             
                           
                         
                         ) 
                       
                       
                         
                            
                           
                             20 
                              
                             ° 
                              
                             
                                 
                             
                              
                             
                               C 
                               . 
                               
                                 - 
                                 
                                   T 
                                   
                                     gas 
                                     , 
                                     0 
                                   
                                 
                               
                             
                           
                            
                         
                         dT 
                       
                     
                   
                 
               
               
                 
                   Eq 
                   . 
                   
                       
                   
                    
                   
                     ( 
                     5 
                     ) 
                   
                 
               
             
             
               
                 
                   
                     V 
                     
                       gas 
                       , 
                       
                         0 
                         @ 
                         
                           
                             T 
                             ^ 
                           
                           
                             gas 
                             , 
                             0 
                           
                         
                       
                     
                   
                   = 
                   
                     
                       V 
                       
                         tot 
                         , 
                         in 
                       
                     
                     - 
                     
                       A 
                       × 
                       
                         
                           S 
                           ^ 
                         
                         0 
                       
                     
                     - 
                     
                       V 
                       
                         oil 
                         , 
                         
                           0 
                           @ 
                           
                             
                               T 
                               ^ 
                             
                             gas 
                           
                         
                         , 
                         0 
                       
                     
                   
                 
               
               
                 
                   Eq 
                   . 
                   
                       
                   
                    
                   
                     ( 
                     6 
                     ) 
                   
                 
               
             
             
               
                 
                   
                     
                       
                         V 
                         
                           gas 
                           , 
                           
                             0 
                             @ 
                             
                               
                                 T 
                                 ^ 
                               
                               
                                 gas 
                                 , 
                                 , 
                                 0 
                               
                             
                           
                         
                       
                        
                       
                         ( 
                         
                           
                             
                               P 
                               ^ 
                             
                             
                               gas 
                               , 
                               0 
                             
                           
                           + 
                           14.7 
                         
                         ) 
                       
                     
                     
                       
                         
                           T 
                           ^ 
                         
                         
                           gas 
                           , 
                           0 
                         
                       
                       × 
                       
                         Z 
                          
                         
                           ( 
                           
                             
                               
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                                 0 
                               
                             
                             , 
                             
                               
                                 T 
                                 ^ 
                               
                               
                                 gas 
                                 , 
                                 0 
                               
                             
                           
                           ) 
                         
                       
                     
                   
                   = 
                   
                     
                       
                         
                           
                             ( 
                             
                               
                                 V 
                                 
                                   tot 
                                   , 
                                   
                                     in 
                                      
                                     
                                       - 
                                     
                                      
                                     air 
                                   
                                 
                               
                               - 
                               
                                 A 
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                               - 
                               
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                                   , 
                                   
                                     0 
                                     @ 
                                     
                                       
                                         T 
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                                         0 
                                       
                                     
                                   
                                 
                               
                               - 
                               
                                 Δ 
                                  
                                 
                                     
                                 
                                  
                                 
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                                     oil 
                                      
                                     
                                       - 
                                     
                                      
                                     
                                       added 
                                       @ 
                                       
                                         
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                                           gas 
                                           , 
                                           0 
                                         
                                       
                                     
                                   
                                 
                               
                             
                             ) 
                           
                         
                       
                       
                         
                           
                             ( 
                             
                               
                                 
                                   P 
                                   ^ 
                                 
                                 gas 
                               
                               + 
                               14.7 
                             
                             ) 
                           
                         
                       
                     
                     
                       
                         
                           T 
                           ^ 
                         
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                       × 
                       
                         Z 
                          
                         
                           ( 
                           
                             
                               
                                 P 
                                 ^ 
                               
                               gas 
                             
                             , 
                             
                               
                                 T 
                                 ^ 
                               
                               gas 
                             
                           
                           ) 
                         
                       
                     
                   
                 
               
               
                 
                   Eq 
                   . 
                   
                       
                   
                    
                   
                     ( 
                     7 
                     ) 
                   
                 
               
             
             
               
                 
                   
                     Δ 
                      
                     
                         
                     
                      
                     
                       V 
                       
                         oil 
                          
                         
                           - 
                         
                          
                         
                           added 
                           @ 
                           
                             
                               T 
                               ^ 
                             
                             
                               gas 
                               , 
                               0 
                             
                           
                         
                       
                     
                   
                   = 
                   
                     
                       ( 
                       
                         
                           V 
                           
                             tot 
                             , 
                             
                               in 
                                
                               
                                 - 
                               
                                
                               air 
                             
                           
                         
                         - 
                         
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                           S 
                         
                         - 
                         
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                             , 
                             
                               0 
                               @ 
                               
                                 
                                   T 
                                   ^ 
                                 
                                 
                                   gas 
                                   , 
                                   0 
                                 
                               
                             
                           
                         
                       
                       ) 
                     
                     - 
                     
                       ( 
                       
                         
                           
                             
                               
                                 T 
                                 ^ 
                               
                               gas 
                             
                             × 
                             
                               Z 
                                
                               
                                 ( 
                                 
                                   
                                     
                                       P 
                                       ^ 
                                     
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                                   , 
                                   
                                     
                                       T 
                                       ^ 
                                     
                                     gas 
                                   
                                 
                                 ) 
                               
                             
                           
                           
                             ( 
                             
                               
                                 
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                                   ^ 
                                 
                                 gas 
                               
                               + 
                               14.7 
                             
                             ) 
                           
                         
                         × 
                         
                           
                             
                               V 
                               
                                 gas 
                                 , 
                                 
                                   0 
                                   @ 
                                   
                                     
                                       T 
                                       ^ 
                                     
                                     
                                       gas 
                                       , 
                                       0 
                                     
                                   
                                 
                               
                             
                              
                             
                               ( 
                               
                                 
                                   
                                     P 
                                     ^ 
                                   
                                   
                                     gas 
                                     , 
                                     0 
                                   
                                 
                                 + 
                                 14.7 
                               
                               ) 
                             
                           
                           
                             
                               
                                 T 
                                 ^ 
                               
                               
                                 gas 
                                 , 
                                 0 
                               
                             
                             × 
                             
                               Z 
                                
                               
                                 ( 
                                 
                                   
                                     
                                       P 
                                       ^ 
                                     
                                     
                                       gas 
                                       , 
                                       0 
                                     
                                   
                                   , 
                                   
                                     
                                       T 
                                       ^ 
                                     
                                     
                                       gas 
                                       , 
                                       0 
                                     
                                   
                                 
                                 ) 
                               
                             
                           
                         
                       
                       ) 
                     
                   
                 
               
               
                 
                   Eq 
                   . 
                   
                       
                   
                    
                   
                     ( 
                     8 
                     ) 
                   
                 
               
             
             
               
                 
                   
                     Δ 
                      
                     
                         
                     
                      
                     
                       V 
                       
                         oil 
                          
                         
                           - 
                         
                          
                         
                           added 
                           @ 
                           20 
                         
                       
                     
                   
                   = 
                   
                     Δ 
                      
                     
                         
                     
                      
                     
                       
                         
                           V 
                           
                             oil 
                              
                             
                               - 
                             
                              
                             
                               added 
                               @ 
                               
                                 
                                   T 
                                   ^ 
                                 
                                 
                                   gas 
                                   , 
                                   0 
                                 
                               
                             
                           
                         
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                           ( 
                           
                             1 
                             + 
                             
                               α 
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                               × 
                               
                                 sign 
                                  
                                 
                                   ( 
                                   
                                     20 
                                      
                                     ° 
                                      
                                     
                                         
                                     
                                      
                                     
                                       C 
                                       . 
                                       
                                         - 
                                         
                                           
                                             T 
                                             ^ 
                                           
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                                   ) 
                                 
                               
                             
                           
                           ) 
                         
                       
                       
                         
                            
                           
                             20 
                              
                             ° 
                              
                             
                                 
                             
                              
                             
                               C 
                               . 
                               
                                 - 
                                 
                                   
                                     T 
                                     ^ 
                                   
                                   gas 
                                 
                               
                             
                           
                            
                         
                         dT 
                       
                     
                   
                 
               
               
                 
                   Eq 
                   . 
                   
                       
                   
                    
                   
                     ( 
                     9 
                     ) 
                   
                 
               
             
           
         
       
     
         [0078]    In various embodiments, comparator  530  may compare added oil  521  with one or more servicing thresholds. Comparator  530  may receive computed oil loss  528  from memory  626 . In various embodiments, computed oil loss  528  may be equal to oil loss  211  of  FIG. 2 . Thus, as an operator adds oil to a shock strut, comparator  530  may actively compare updated added oil  521  with one or more servicing thresholds to indicate to the operator when to stop or slow the process of filling the shock strut with oil as described herein. In various embodiments, added oil  521  may comprise a value, data point, datum, or the like. 
         [0079]    Accordingly, as illustrated in  FIG. 5 , first IF logic  534  may determine if desired oil volume  230  minus oil loss  211  plus added oil  521  is less than or equal to a second oil volume threshold. The volume of oil in the shock strut may be less than a desired volume in response to first IF logic  534  being true. Thus, comparator  530  may generate a datum (also referred to herein as a first datum) in response to first IF logic  534  being true (see step  802 ). Accordingly, the datum may indicate to an indicator, such as indicator  542  for example, to indicate to an operator to continue adding oil to a shock strut. For example, a datum may comprise a signal, data point, value, or the like which indicates to a controller that first IF logic  534  is true. An indicator  542  may indicate to the operator to continue adding oil to the shock strut in response to first IF logic  534  being true. Thus, a shock strut may receive oil in response to first IF logic  534  being true (see step  803 ). 
         [0080]    As illustrated in  FIG. 5 , second IF logic  536  may determine if desired oil volume  230  minus oil loss  211  plus added oil  521  is less than or equal to a first oil volume threshold and is greater than the second oil volume threshold. The volume of oil in the shock strut may be less than a desired volume in response to IF logic  536  being true. An indicator  544  may indicate to the operator to continue adding oil to the shock strut in response to second IF logic  536  being true. An indicator  544  may indicate to the operator to continue adding oil to the shock strut at a slower rate in response to second IF logic  536  being true. 
         [0081]    As previously mentioned, oil addition calculator  520  may calculate the volume of added oil  521  to a shock strut as oil is added to a shock strut. Accordingly, an updated value of added oil (also referred to herein as a second fluid level)  521  may be calculated by oil addition calculator  520  (see step  804 ). In various embodiments, the value of added oil  521  may increase as oil is added to a shock strut. 
         [0082]    As illustrated in  FIG. 5 , third IF logic  538  may determine if desired oil volume  230  minus oil loss  211  plus added oil  521  is less than or equal to desired oil volume  230  scaled by a factor such as, for example, 1.02 and is greater than the first oil volume threshold. The volume of oil in the shock strut may be equal to a desired volume in response to third IF logic  538  being true. Thus, comparator  530  may generate a datum (also referred to herein as a second datum) in response to third IF logic  538  being true (see step  805 ). Accordingly, the datum may indicate to an indicator, such as indicator  546  for example, to indicate to an operator to stop adding oil to a shock strut. An indicator  546  may indicate to the operator to stop adding oil to the shock strut in response to third IF logic  538  being true. Thus, a shock strut may stop from receiving oil in response to third IF logic  538  being true. 
         [0083]    As illustrated in  FIG. 5 , fourth IF logic  540  may determine if desired oil volume  230  minus oil loss  211  plus added oil  521  is greater than desired oil volume  230  scaled by a factor such as, for example, 1.02. The volume of oil in the shock strut may be greater than a desired volume in response to fourth IF logic  540  being true. An indicator  548  may indicate to the operator that the shock strut has been over filled with oil in response to fourth IF logic  540  being true. 
         [0084]    An operator may be instructed to stop adding oil to a shock strut at which moment the operator would stop from adding oil to the shock strut in response to third IF logic  538  being true. The operator may then indicate to oil level adjustment process  500  that the oil volume adjustment process is finished by, for example, selecting selectable finish tab  424 . Subsequently, finish decision  522  may determine if the finish tab  424  is selected and indicate to update process  524  to update and store a new oil volume (also referred to herein as a final fluid level)  525  to memory  526  (see step  806 ) in response to finish tab  424  being selected. New oil volume  525  may be calculated by update process  524  by taking desired oil volume  230  minus oil loss  211  plus added oil  521 . 
         [0085]    In various embodiments, indicator  542 , indicator  544 , indicator  546 , and indicator  548  may be located on display  400  via indicator  440 , for example. Thus, indicator  440  may indicate when to stop adding oil to a shock strut. Accordingly, oil level adjustment process  500  may generate an indicator corresponding to added oil  521 . 
         [0086]    With reference to  FIG. 9 , a method or process  900  for servicing gas within a shock strut is provided. With reference to  FIG. 4  and  FIG. 6 , selectable start tab  426  may be selected by an operator, to start or initiate a gas level adjustment process  600 . In various embodiments, gas level adjustment process  600  may comprise system program instructions and/or controller instructions. Gas level adjustment process  600  may be located on handheld device  302 . However, it is contemplated that gas level adjustment process  600  may be located on a controller located on an aircraft or other vehicle. In various embodiments, gas level adjustment process  600  may be similar to oil level adjustment process  500 . 
         [0087]    In various embodiments, gas level adjustment process  600  may include start decision  602 , gas addition calculator  620 , and comparator  630 . In various embodiments, gas level adjustment process  600  may include finish decision  622 , update process  624 , and memory  626 . In various embodiments, comparator  630  may include one or more IF logics. As illustrated in  FIG. 6 , comparator  630  includes first IF logic  634 , second IF logic  636 , third IF logic  638 , and fourth IF logic  640 . 
         [0088]    Start decision  602  may determine if an operator has indicated to start a gas level adjustment process. For example, an operator may select selectable start tab  426  and in response, start decision  602  may indicate to start gas level adjustment process  600 . In various embodiments, gas addition calculator  620  may quantify the number of moles of gas added to a shock strut in response to start decision  602  being true. Gas addition calculator  620  may receive initial gas pressure  618 , initial gas temperature  616 , and initial shock strut stroke  614  from initial parameter retriever  606 . Initial gas pressure  618 , initial gas temperature  616 , and initial shock strut stroke  614  may be the gas pressure, gas temperature, and shock strut stroke at the onset of the gas level adjustment process  600 , respectively. Gas addition calculator  620  may receive updated gas pressure  612 , updated gas temperature  610 , and updated shock strut stroke  608  from updating parameter retriever  604 . Updating parameter retriever may acquire updated gas pressure  612 , updated gas temperature  610 , and updated shock strut stroke  608  at a pre-determined rate, such as 10 Hz, for example. Updated gas pressure  612 , updated gas temperature  610 , and updated shock strut stroke  608  may be the gas pressure, gas temperature, and shock strut stroke, respectively, as measured by the shock strut sensors during the gas level adjustment process  600 . Gas addition calculator  620  may use equation 10 through equation 13 to calculate the number of moles of added gas (also referred to herein as a first fluid level)  621  to a shock strut (see step  901 ). 
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         [0089]    In various embodiments, comparator  630  may compare number of moles of added gas  621  with one or more servicing thresholds. Comparator  630  may receive computed gas loss  628  from memory  626 . In various embodiments, computed gas loss  628  may be equal to gas loss  212  of  FIG. 2 . Thus, as an operator adds gas to a shock strut, comparator  630  may actively compare updated number of moles of added gas  621  with one or more servicing thresholds to indicate to the operator when to stop or slow the process of filling the shock strut with gas as described herein (see step  903  and step  904 ). In various embodiments, number of moles of added gas  621  may comprise a value, data point, or the like. 
         [0090]    Accordingly, as illustrated in  FIG. 6 , first IF logic  634  may determine if a desired number of moles of gas minus number of moles of gas loss  212  plus number of moles of added gas  621  is less than or equal to a second gas number of moles threshold. The number of moles of gas in the shock strut may be less than a desired level in response to first IF logic  634  being true. Thus, comparator  630  may generate a datum (also referred to herein as a first datum) in response to first IF logic  634  being true (see step  902 ). Accordingly, the datum may indicate to an indicator, such as indicator  642  for example, to indicate to an operator to continue adding gas to a shock strut. For example, a datum may comprise a signal, data point, value, or the like which indicates to a controller that first IF logic  634  is true. An indicator  642  may indicate to the operator to continue adding gas to the shock strut in response to first IF logic  634  being true. Thus, a shock strut may receive gas in response to first IF logic  634  being true (see step  903 ). 
         [0091]    As illustrated in  FIG. 6 , second IF logic  636  may determine if a desired number of moles of gas minus number of moles of gas loss  212  plus number of moles of added gas  621  is less than or equal to a first gas level threshold and is greater than the second gas level threshold. The number of moles of gas in the shock strut may be less than a desired level in response to second IF logic  636  being true. An indicator  644  may indicate to the operator to continue adding gas to the shock strut in response to second IF logic  636  being true. An indicator  644  may indicate to the operator to slow the rate at which the operator is adding gas to the shock strut in response to second IF logic  636  being true. 
         [0092]    As previously mentioned, gas addition calculator  620  may calculate the number of moles of added gas  621  to a shock strut as gas is added to the shock strut. Accordingly, an updated value of added gas (also referred to herein as a second fluid level)  621  may be calculated by gas addition calculator  620  (see step  904 ). In various embodiments, the value of number of moles of added gas  621  may increase as gas is added to a shock strut. 
         [0093]    As illustrated in  FIG. 6 , third IF logic  638  may determine if a desired number of moles of gas minus number of moles of gas loss  212  plus number of moles of added gas  621  is less than or equal to a desired number of moles of gas scaled by a factor such as, for example, 1.02 and is greater than the first gas level threshold. The number of moles of gas in the shock strut may be equal to a desired level in response to third IF logic  638  being true. Thus, comparator  630  may generate a datum (also referred to herein as a second datum) in response to third IF logic  638  being true (see step  905 ). Accordingly, the datum may indicate to an indicator, such as indicator  646  for example, to indicate to an operator to stop adding gas to a shock strut. An indicator  646  may indicate to the operator to stop adding gas to the shock strut in response to third IF logic  638  being true. Thus, a shock strut may stop from receiving gas in response to third IF logic  638  being true. 
         [0094]    As illustrated in  FIG. 6 , fourth IF logic  640  may determine if a desired number of moles of gas minus number of moles of gas loss  212  plus number of moles of added gas  621  is greater than a desired number of moles of gas scaled by a factor such as, for example, 1.02. The number of moles of gas in the shock strut may be greater than a desired level in response to fourth IF logic  640  being true. An indicator  648  may indicate to the operator that the shock strut has been over filled with gas in response to fourth IF logic  640  being true. 
         [0095]    An operator may be instructed to stop adding gas to a shock strut at which moment the operator would stop from adding gas to the shock strut in response to third IF logic  638  being true. The operator may then indicate to gas level adjustment process  600  that the gas volume adjustment process is finished by, for example, selecting selectable finish tab  428 . Subsequently, finish decision  622  may determine if the finish tab  428  is selected and indicate to update process  624  to update and store a new gas number of moles (also referred to herein as a final fluid level)  625  to memory  626  (see step  906 ) in response to finish tab  428  being selected. New gas number of moles  625  may be calculated by taking a desired number of moles of gas minus number of moles of gas loss  212  plus number of moles of added gas  621 . 
         [0096]    In various embodiments, indicator  642 , indicator  644 , indicator  646 , and indicator  648  may be located on display  400  via indicator  440 , for example. Thus, indicator  440  may indicate when to stop adding gas to a shock strut. Accordingly, gas level adjustment process  600  may generate an indicator corresponding to number of moles of added gas  621 . 
         [0097]    Benefits, other advantages, and solutions to problems have been described herein with regard to specific embodiments. Furthermore, the connecting lines shown in the various figures contained herein are intended to represent exemplary functional relationships and/or physical couplings between the various elements. It should be noted that many alternative or additional functional relationships or physical connections may be present in a practical system. However, the benefits, advantages, solutions to problems, and any elements that may cause any benefit, advantage, or solution to occur or become more pronounced are not to be construed as critical, required, or essential features or elements of the disclosure. The scope of the disclosure is accordingly to be limited by nothing other than the appended claims, in which reference to an element in the singular is not intended to mean “one and only one” unless explicitly so stated, but rather “one or more.” Moreover, where a phrase similar to “at least one of A, B, or C” is used in the claims, it is intended that the phrase be interpreted to mean that A alone may be present in an embodiment, B alone may be present in an embodiment, C alone may be present in an embodiment, or that any combination of the elements A, B and C may be present in a single embodiment; for example, A and B, A and C, B and C, or A and B and C. Different cross-hatching is used throughout the figures to denote different parts but not necessarily to denote the same or different materials. 
         [0098]    Systems, methods and apparatus are provided herein. In the detailed description herein, references to “one embodiment”, “an embodiment”, “various embodiments”, etc., indicate that the embodiment described may include a particular feature, structure, or characteristic, but every embodiment may not necessarily include the particular feature, structure, or characteristic. Moreover, such phrases are not necessarily referring to the same embodiment. Further, when a particular feature, structure, or characteristic is described in connection with an embodiment, it is submitted that it is within the knowledge of one skilled in the art to affect such feature, structure, or characteristic in connection with other embodiments whether or not explicitly described. After reading the description, it will be apparent to one skilled in the relevant art(s) how to implement the disclosure in alternative embodiments. 
         [0099]    Furthermore, no element, component, or method step in the present disclosure is intended to be dedicated to the public regardless of whether the element, component, or method step is explicitly recited in the claims. No claim element herein is to be construed under the provisions of 35 U.S.C. 112(f) unless the element is expressly recited using the phrase “means for.” As used herein, the terms “comprises”, “comprising”, or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus.