ACTIVE DRAG CONTROL SYSTEM FOR AN AIRCRAFT

Abstract

An aircraft includes an active drag control system such as a Laminar Flow Control (LFC) system having a port LFC apparatus and a starboard LFC apparatus. The aircraft has a control system to test how efficiently the LFC system is working by differentially operating the port LFC apparatus and the starboard LFC apparatus, for example by deactivating either LFC apparatus, and measuring the effect on the direction of flight of the aircraft. The control system also can change the direction of the aircraft, and trim the aircraft, by differentially operating the port LFC apparatus and the starboard LFC apparatus.

Claims

1. A laminar flow control (LFC) system for an aircraft, the LFC system comprising: a first LFC apparatus for use in a port aircraft structure, wherein the first LFC apparatus is operable to promote laminar flow of air over the port aircraft structure and thereby cause a reduction in drag on a port side of the aircraft; a second LFC apparatus for use in a starboard aircraft structure, wherein the second LFC apparatus is operable to promote laminar flow of air over the starboard aircraft structure and thereby cause a reduction in drag on a starboard side of the aircraft; and a control system configured to perform a test of the LFC system while the aircraft is flying a first direction by: differentially operating the first LFC apparatus and the second LFC apparatus to change an amount of drag on the port side of the aircraft caused by the port aircraft structure relative to an amount of drag on the starboard side of the aircraft caused by the starboard aircraft structure; measuring an effect of differentially operating the first LFC apparatus and the second LFC apparatus on the direction of flight of the aircraft; and determining, based on the measurement, how efficiently the first LFC apparatus and/or the second LFC apparatus is or are operating.

2. The LFC system according to claim 1, wherein the control system is configured to measure the effect of differentially operating the first LFC apparatus and the second LFC apparatus by measuring a change of direction of the aircraft.

3. The LFC system according to claim 1, wherein the control system is configured to measure the effect of differentially operating the first LFC apparatus and the second LFC apparatus by measuring an amount of corrective action required to restore a direction of flight to the first direction, and/or maintain a direction of flight in the first direction.

4. The LFC system according to claim 3, wherein the corrective action comprises changing a position of a control surface of the aircraft.

5. The LFC system according to claim 3, wherein the corrective action comprises changing a thrust provided by an engine of the aircraft.

6. The LFC system according to claim 1, wherein the LFC system comprises a plurality of independently operable first LFC apparatuses for use on the port side of the aircraft, and a corresponding plurality of independently operable second LFC apparatuses for use on the starboard side of the aircraft; wherein each first LFC apparatus and its corresponding second LFC apparatus define a pair of corresponding LFC apparatuses; wherein the control system is configured to differentially operate each pair of corresponding LFC apparatuses in turn to determine how efficiently each first LFC apparatus and each second LFC apparatus are operating.

7. The LFC system according to claim 1, wherein the control system is configured to initiate the test autonomously at predetermined times during flight.

8. The LFC system according to claim 1, wherein the control system is configured to determine a range of the aircraft in dependence on the efficiency of operation of the LFC system.

9. A laminar flow control (LFC) system for an aircraft, the LFC system comprising: a first LFC apparatus for use in a port aircraft structure, wherein the first LFC apparatus is operable to promote laminar flow of air over the port aircraft structure and thereby cause a reduction in drag on a port side of the aircraft; a second LFC apparatus for use in a starboard aircraft structure, wherein the starboard LFC apparatus is operable to promote laminar flow of air over the starboard aircraft structure and thereby cause a reduction in drag on a starboard side of the aircraft; and a control system configured to control a direction of the aircraft during flight by differentially operating the first LFC apparatus and the second LFC apparatus to change an amount of drag on the port side of the aircraft caused by the port aircraft structure relative to an amount of drag on the starboard side of the aircraft caused by the starboard aircraft structure.

10. An LFC system according to claim 9, wherein the control system is configured to initiate a change of direction in response to commands from an autopilot system of the aircraft.

11. An LFC system according to claim 9, wherein the control system is configured to cause a change of direction without movement of a rudder and/or without movement of an aileron of the aircraft.

12. The LFC system according to claim 9, wherein the control system is configured to perform a test of the LFC system during a change of direction by: measuring a rate of change of the direction of the aircraft; and determining, based on the measurement, how efficiently the first LFC apparatus or the second LFC apparatus is operating.

13. A laminar flow control (LFC) system for an aircraft, the LFC system comprising: a first LFC apparatus for use in a port aircraft structure, wherein the first LFC apparatus is operable to promote laminar flow of air over the port aircraft structure and thereby cause a reduction in drag on a port side of the aircraft; a second LFC apparatus for use in a starboard aircraft structure, wherein the starboard LFC apparatus is operable to promote laminar flow of air over the starboard aircraft structure and thereby cause a reduction in drag on a starboard side of the aircraft; and a control system configured to trim the aircraft during flight by differentially operating the first LFC apparatus and the second LFC apparatus to change an amount of drag on the port side of the aircraft caused by the port aircraft structure relative to an amount of drag on the starboard side of the aircraft caused by the starboard aircraft structure.

14. The LFC system according to claim 13, wherein the LFC system comprises a plurality of independently operable first LFC apparatuses for use in a port wing of the aircraft, and a corresponding plurality of independently operable second LFC apparatuses for use in a starboard wing of the aircraft; and wherein the control system is configured to trim the aircraft by differentially operating the first LFC apparatus that is configured to reduce drag caused by a distal end of the port wing and the corresponding second LFC apparatus that is configured to reduce drag caused by a distal end of the starboard wing.

15. The LFC system according to claim 13, wherein the control system is configured to differentially operate the first LFC apparatus and the second LFC apparatus by changing a rate of airflow in the first LFC apparatus and/or the second LFC apparatus.

16. The LFC system according to claim 13, wherein the control system is configured to differentially operate the first LFC apparatus and the second LFC apparatus by deactivating either the first LFC apparatus or the second LFC apparatus.

17. The LFC system according to claim 13, wherein the port aircraft structure and the starboard aircraft structure are each a wing, a portion of a tailplane, or an engine nacelle.

18. The LFC system according to claim 13, wherein the LFC system is a Hybrid Laminar Flow Control (HLFC) system.

19. An aircraft comprising an LFC system according to claim 1.

20. The aircraft according to claim 19, wherein the aircraft is an Unmanned Aerial Vehicle.

21. A control system for an LFC system according to claim 1.

22. A method of testing a laminar flow control (LFC) system of an aircraft, wherein the aircraft comprises: a port aircraft structure comprising a first LFC apparatus operable to promote laminar flow of air over the port aircraft structure and thereby cause a reduction in drag on a port side of the aircraft; and a starboard aircraft structure comprising a second LFC apparatus operable to promote laminar flow of air over the starboard aircraft structure and thereby cause a reduction in drag on a starboard side of the aircraft; and the method comprising: flying the aircraft in a first direction; differentially operating the first LFC apparatus and the second LFC apparatus to change an amount of drag on the port side of the aircraft caused by the port aircraft structure relative to an amount of drag on the starboard side of the aircraft caused by the starboard aircraft structure; measuring an effect of differentially operating the first LFC apparatus and the second LFC apparatus on the direction of flight of the aircraft; and determining, based on the measurement, how efficiently the first LFC apparatus and/or the second LFC apparatus is or are operating.

23. A method of controlling a direction of an aircraft in flight, the aircraft comprising: a port aircraft structure comprising a first LFC apparatus operable to promote laminar flow of air over the port aircraft structure and thereby cause a reduction in drag on a port side of the aircraft; and a starboard aircraft structure comprising a second LFC apparatus operable to promote laminar flow of air over the starboard aircraft structure and thereby cause a reduction in drag on a starboard side of the aircraft; the method comprising: flying the aircraft in a first direction; and differentially operating the first LFC apparatus and the second LFC apparatus to change an amount of drag on the port side of the aircraft caused by the port aircraft structure relative to an amount of drag on the starboard side of the aircraft caused by the starboard aircraft structure.

24. The method according to claim 23, comprising differentially operating the first LFC apparatus and the second LFC apparatus such that the aircraft rotates about a yaw axis and the direction of flight changes, the method comprising, during change in the direction of flight: measuring a rate of change of the direction of the aircraft; and determining, based on the measurement, how efficiently the first LFC apparatus or the second LFC apparatus is operating.

25. A method of trimming an aircraft in flight, the aircraft comprising: a port aircraft structure comprising a first LFC apparatus operable to promote laminar flow of air over the port aircraft structure and thereby cause a reduction in drag on a port side of the aircraft; and a starboard aircraft structure comprising a second LFC apparatus operable to promote laminar flow of air over the starboard aircraft structure and thereby cause a reduction in drag on a starboard side of the aircraft; the method comprising: flying the aircraft in a first direction, wherein the aircraft is out of trim such that there is rotation about a yaw axis; and differentially operating the first LFC apparatus and the second LFC apparatus to change an amount of drag on the port side of the aircraft caused by the port aircraft structure compared to an amount of drag on the starboard side of the aircraft caused by the starboard aircraft structure such that the aircraft becomes trimmed about the yaw axis.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0057] Embodiments of the disclosure herein will now be described by way of example only with reference to the accompanying schematic drawings of which:

[0058] FIG. 1 shows a plan view of an aircraft according to a first embodiment of the disclosure herein;

[0059] FIG. 2 shows a cross-sectional side view of a portion of a wing of the aircraft according to the first embodiment of the disclosure herein;

[0060] FIG. 3 shows a plan view of the aircraft according to the first embodiment of the disclosure herein, with the HLFC apparatus for the starboard wing deactivated;

[0061] FIG. 4 shows a plan view of the aircraft according to the first embodiment of the disclosure herein, demonstrating a first method of testing the LFC system;

[0062] FIG. 5 shows a plan view of the aircraft according to the first embodiment of the disclosure herein, demonstrating a second method of testing the LFC system;

[0063] FIG. 6 shows a plan view of the aircraft according to the first embodiment of the disclosure herein, demonstrating a third method of testing the LFC system;

[0064] FIG. 7 shows a plan view of an aircraft according to a second embodiment of the disclosure herein; and

[0065] FIG. 8 shows a plan view of the aircraft according to the second embodiment of the disclosure herein, demonstrating a method of trimming the aircraft.

DETAILED DESCRIPTION

[0066] FIG. 1 shows an aircraft 100 comprising a central fuselage 102. A port wing 104 is mounted to a port side of the fuselage 102, and a starboard wing 106 is mounted to the starboard side of the fuselage 102. A port engine 108 is mounted to the port wing 104, and a starboard engine 110 is mounted to the starboard wing 106. A tailplane 112 (also known as a horizontal stabilizer) is mounted to an aft section of the fuselage 102. The tailplane has a port section 114 to port of the fuselage 102, and a starboard section 116 to starboard of the fuselage 102.

[0067] The aircraft 100 comprises a Laminar Flow Control (LFC) system according to the first embodiment of the disclosure herein. The LFC system comprises a first (port) HLFC apparatus 118 associated with the port wing 104, and a second (starboard) HLFC apparatus 120 associated with the starboard wing 106.

[0068] The port wing 104 comprises a wing skin 121 comprising a perforated section 122 located at a leading edge of the port wing 104. The first HLFC apparatus 118 comprises a pump (not shown) arranged to generate suction and pull air through the perforated section 122 and into a conduit 123 in the port wing 104. This arrangement is shown schematically in FIG. 2. The first HLFC apparatus 118 is arranged such that air passes through the conduit 123 and is exhausted to the outside airflow.

[0069] Similarly, the starboard wing 106 comprises a wing skin comprising a perforated section 124 located at a leading edge of the starboard wing 106. The second HLFC apparatus 120 comprises a pump arranged to generate suction and pull air through the perforated section 124 and into a conduit in the starboard wing 106. The arrangement is similar to that shown in FIG. 2. The second HLFC apparatus 120 is arranged such that air passes through the conduit and is exhausted to the outside airflow.

[0070] The LFC system further comprises a control system 126 configured to control the first HLFC apparatus 118 and the second HLFC apparatus 120 independently of each other. In particular, the control system 126 is able to independently control the power going to the pump of the first HLFC apparatus 118 and the pump of the second HLFC apparatus 120. The control system 126 is thereby able to independently change the rate of airflow through each of the first HLFC apparatus 118 and the second HLFC apparatus 120, and also independently activate and deactivate each of the first HLFC apparatus 118 and the second HLFC apparatus 120.

[0071] During flight, with the LFC system not in use (i.e. with the pumps deactivated), air flows over the wing skin and, at some point, the boundary layer of air (i.e. the layer of air adjacent the wing skin) transitions from laminar to turbulent flow. When the LFC system is used during flight, the suction through the perforated sections 122, 124 delays the transition of the boundary layer from turbulent to laminar flow. Delaying the transition of the boundary layer from turbulent to laminar flow has the effect of reducing the drag caused by the wings 104, 106.

[0072] The ability of the control system 126 to independently control each HLFC apparatus means that the first HLFC system 118 and the second HLFC system 120 can be differentially operated. The differential operation may involve the rate of airflow in the first HLFC apparatus 118 being changed relative to the rate of airflow in the second HLFC apparatus 120. Similarly, the differential operation may involve one of the HLFC apparatus being active (e.g. switched on), while the other HLFC apparatus is not active (e.g. switched off).

[0073] By reducing the rate of airflow in an HLFC apparatus, or by deactivating the HLFC apparatus, the amount of drag reduction provided by the HLFC apparatus reduces. Accordingly, the drag caused by the associated aircraft structure (in this case the wing) increases. If the HLFC apparatus 118, 120 are differentially operated, then the drag forces on the wings 104, 106 may become imbalanced. In other words, there may be an asymmetry in the drag about the fuselage 102. The imbalance (asymmetry) may result in a net turning force acting on the aircraft 100.

[0074] FIG. 3 shows an example in which the second HLFC apparatus 120 is deactivated, while the first HLFC apparatus 118 is operated at full power. As indicated by the size of the arrows, the drag forces caused by the starboard wing 106 are higher than the drag forces caused by the port wing 104. The imbalance in forces about the fuselage 102 result in a turning moment (R) about the yaw axis (the yaw axis extending out of the page). If the turning forces are not countered by movement of a control surface, such as a rudder, the aircraft will begin to change direction to starboard.

[0075] The disclosure herein seeks to take advantage of this effect in the following ways: (i) to determine how efficiently the LFC system, or aspects thereof, are operating, (ii) to change the direction of the aircraft, and (iii) to trim the aircraft.

[0076] Accordingly, the control system 126 is configured to perform a test of the LFC system during flight. The test is performed by the control system 126 differentially operating the first HLFC apparatus 118 and the second HLFC apparatus 120, measuring the effect of the differentially operation on the direction of flight of the aircraft, and determining, on the basis of the measurement, how efficiently the first HLFC apparatus 118 and/or the second HLFC apparatus 120 was operating.

[0077] A first method of testing the LFC system will now be described with reference to FIG. 4. In an initial step, the control system 126 determines whether the flight conditions are suitable for the test to be initiated. The control system 126 thereby verifies that the aircraft 100 is flying at a constant heading, at a constant altitude, and is in trim. If these criteria are met, the control system 126 is configured to proceed with the test.

[0078] The control system 126 then differentially operates the first HLFC apparatus 118 and the second HLFC apparatus 120 by leaving the first HLFC apparatus 118 active and operating at a power which maximizes the amount of drag reduction (minimizes drag), and deactivating the second HLFC apparatus 120. The aircraft 100 is then allowed to fly for a predetermined period of time (ti) without movement of any control surfaces or change in engine power. The predetermined period of time may vary with aircraft type, airspeed, etc.

[0079] The direction of the aircraft 100 is indicated by on-board systems, including a heading indicator and a satellite navigation system. The control system 126 interfaces with these systems and uses the output of these systems to measure how the direction of the aircraft 100 has changed over the predetermined period of time. In some embodiments, the control system 126 measures the change in heading (8). In some embodiments, the control system 126 measures the magnitude of deviation (D) from a straight flightpath as indicated by the track of the aircraft on a GPS system.

[0080] Using these measurements, the control system 126 then determines how efficiently the second HLFC apparatus 120 was working. The control system 126 comprises a function which relates the direction change measurements (e.g. heading change or distance from straight flight path) to a value of efficiency. The control system 126 uses the function to obtain an indication of the efficiency of the second HLFC apparatus 120.

[0081] In alternative embodiments, the efficiency of the second HLFC apparatus 120 may be determined on the basis of a comparison of the measured direction change with an expected direction change when the HLFC apparatus 120 is operating at maximum efficiency. For example, the expected heading change over the predetermined time period may be 5 degrees when the second HLFC apparatus 120 is operating at maximum efficiency. If the measured heading change was 2.5 degrees, the control system 126 may determine that the second HLFC apparatus 120 was operating at approximately 50% efficiency.

[0082] In some embodiments, the control system 126 determines a rate of change of direction (e.g. the rate of change of heading and/or rate of change of distance from a straight flight path). The control system uses the rate of change to calculate a value of efficiency (e.g. using a function, lookup table, or comparison). In embodiments, the first HLFC apparatus 118 and the second HLFC apparatus 120 are differentially operated only for as long as is required to determine the rate of change of direction with a sufficient degree of certainty.

[0083] The control system 126 then reactivates the second HLFC apparatus 120, and the control surfaces are used to bring the aircraft 100 back to the desired course. It is assumed that both the first HLFC apparatus 118 and the second HLFC apparatus 120 are operating at a comparable efficiency. If the efficiency is below a threshold value, then the operator of the aircraft 100 is alerted that cleaning or maintenance of the LFC system is required. The control system 126 can also update the predicted range of the aircraft 100 in dependence on the efficiency so measured.

[0084] In alternative embodiments, the control unit 126 performs a subsequent test in which the first HLFC apparatus 118 is deactivated while the second HLFC apparatus 118 is active and running at a power that maximizes the amount of drag reduction (minimizes drag).

[0085] A second method of testing the LFC system will now be described with reference to FIG. 5. The second method begins in the same way as the first method: the control system 126 determines whether the flight conditions are suitable for the test to be initiated, and the control system 126 differentially operates the first HLFC apparatus 118 and the second HLFC apparatus 120 by deactivating the second HLFC apparatus 120. As soon as a change in direction of the aircraft 100 is sensed, the control system 126 instructs a corrective action in the form of a corrective movement (M) of the rudder 128 in order to create a corrective force (F) to counteract the imbalance in drag forces on the wings 104, 106 and bring the aircraft 100 back to the direction of flight prior to initiation of the test.

[0086] The control system 126 measures the amount of rudder 128 movement required to maintain the direction of flight. The amount of rudder movement is related to the efficiency at which the second HLFC apparatus 120 was operating. In a similar way to the first method, the control system 126 uses a function (or in alternative embodiments a lookup table or comparison) to determine how efficiently the second HLFC apparatus 120 was operating on the basis of the amount of rudder movement required. After the efficiency is calculated, the second HLFC apparatus 120 is reactivated and the rudder is returned to a neutral position.

[0087] A third method of testing the LFC system will now be described with reference to FIG. 6. The third method is similar to the second method, however, the corrective action is an increase in thrust produced by the starboard engine 110. The control system 126 measures the extra amount of throttle required for the starboard engine 110 in order to bring the aircraft 100 back to the direction of flight prior to initiation of the test. The control system 126 then uses a function (or in alternative embodiments a lookup table or comparison) to determine how efficiently the second HLFC apparatus 120 was operating on the basis of the extra amount of throttle required. After the efficiency is calculated, the second HLFC apparatus 120 is turned back on and the starboard engine is throttled back to its initial level of thrust. In alternative embodiments, the corrective action could be a reduction in the trust produced by the port engine 108.

[0088] In addition to testing the efficiency of the LFC system, the control unit 126 is also configured to cause an intentional change of direction of the aircraft 100 in response to a command from the autopilot system, or operator, of the aircraft 100. The change of direction is effected by deactivating the HLFC apparatus 118, 120 on the side of the aircraft 100 that corresponds to the direction in which the aircraft 100 is to turn. Once the required change of direction is achieved, as determined by on-board systems including the heading indicator, the deactivated HLFC apparatus 118, 120 is reactivated.

[0089] During a change of direction, the rate of change of direction may be measured. The rate of change of direction measurement can, as per the first method described above, be used to provide an indication of the efficiency of the LFC system.

[0090] In the above described methods, differential operation of the first HLFC apparatus 118 and second HLFC apparatus 120 has been achieved by deactivating one of the HLFC apparatuses 118, 120, while the other remains active. In alternative methods, the differential operation is achieved by changing the rate of airflow in the first HLFC apparatus 118 relative to the second HLFC apparatus 120, without fully deactivating either HLFC apparatus 118, 120.

[0091] The control unit 126 is also configured to trim the aircraft 100. Trimming is achieved by changing the rate of airflow in the first HLFC apparatus 118 relative to the rate of airflow in the second HLFC apparatus 120, which thereby changes the drag caused by the port side of the aircraft 100 relative to the drag caused by the starboard side.

[0092] In embodiments, the control system 126 is configured to automatically detect the aircraft 100 is out of trim and automatically operate the HLFC apparatuses 118, 120 to improve trim. In embodiments, the control system 126 determines the aircraft is out of trim by detecting that flight control surfaces, such as the rudder, are required to be positioned away from a neutral position in order to maintain a straight course, or by detecting that the aircraft 100 consistently departs from a straight course despite such flight control surfaces being in a neutral position.

[0093] FIG. 7 shows an aircraft 200 according to a second embodiment of the disclosure herein. The aircraft 200 comprises a port wing 204 and a starboard wing 206. The port wing 204 comprises three independently operable HLFC apparatuses 218. The starboard wing 206 comprises three corresponding independently operable HLFC apparatuses 220. Each HLFC apparatus is associated with a different section of a perforated leading edge 222, 224 of the respective wing 204, 206. The sections are distributed along the length of each wing 204, 206 in the spanwise direction.

[0094] The aircraft 200 further comprises an independently operable HLFC apparatus associated with a perforated leading edge region 230 of the port section 214 of the tailplane 212, and an independently operable HLFC apparatus associated with a perforated leading edge region 232 of the starboard section 216 of the tailplane 212. The port engine 208 nacelle and the starboard engine 210 nacelle also comprise perforated surfaces 234, 236. An independently operable LFC apparatus is associated with the perforated surface of each engine nacelle.

[0095] A control system 226 is configured to independently control each HLFC/LFC apparatus. The control system 226 is configured to test each corresponding pair of HLFC/LFC apparatuses in turn in order to determine their efficiency. For example, each HLFC apparatus 218 associated with a section of the port wing 204 may be deactivated in turn, followed by the HLFC apparatus associated with the port section 214 of the tailplane 212, and the LFC apparatus associated with the port engine 208 nacelle. During each deactivation, the effect on the heading of the aircraft is measured and the efficiency of the HLFC/LFC apparatus is obtained.

[0096] The control unit 226 may cause a change of direction of the aircraft 200, as per the first embodiment, by deactivating all or some of the HLFC/LFC apparatuses on one side of the aircraft 200.

[0097] As shown in FIG. 8, the control system 226 is also configured to trim the aircraft 200. The trim may be achieved by differentially operating a first HLFC apparatus 218 associated with the perforated section located at a distal end (i.e. outboard-most end) of the port wing 204, and a second HLFC apparatus 220 associated with the perforated section located at a distal end (i.e. outboard-most end) of the starboard wing 206. The differential operation of these HLFC apparatuses is used to counteract an existing imbalance in the forces acting on the aircraft 200 which is causing the aircraft to be out of trim around the yaw axis. In embodiments, further corresponding pairs of HLFC/LFC apparatus may also be differentially operated in order to achieve trim of the aircraft 200.

[0098] In embodiments, the control system 226 may differentially operate the corresponding HLFC/LFC apparatuses by changing the relative rates of airflow therethrough, without fully deactivating either HLFC/LFC apparatus.

[0099] While the disclosure herein has been described and illustrated with reference to particular embodiments, it will be appreciated by those of ordinary skill in the art that the disclosure herein lends itself to many different variations not specifically illustrated herein. By way of example only, certain possible variations will now be described.

[0100] In embodiments, the aircraft comprises alternative or additional active drag control systems which are differentially operable as between the port and starboard sides of the aircraft. In such embodiments, the control unit is configured to operate the active drag control system in order to determine the efficiency of the system, control the direction of the aircraft, and trim the aircraft.

[0101] It will be appreciated that the rate of airflow in an HLFC/LFC apparatus may be reduced to negligible amounts, such that the effect is the same as deactivating the HLFC/LFC apparatus. Where the context allows, references to deactivating, or turning off, an HLFC/LFC apparatus encompasses reducing the airflow to an amount in which the drag reduction effect is negligible.

[0102] Where in the foregoing description, integers or elements are mentioned which have known, obvious or foreseeable equivalents, then such equivalents are herein incorporated as if individually set forth. Reference should be made to the claims for determining the true scope of the disclosure herein, which should be construed so as to encompass any such equivalents. It will also be appreciated by the reader that integers or features of the disclosure herein that are described as preferable, advantageous, convenient or the like are optional and do not limit the scope of the independent claims. Moreover, it is to be understood that such optional integers or features, while of possible benefit in some embodiments of the disclosure herein, may not be desirable, and may therefore be absent, in other embodiments.

[0103] At least some or all of the subject matter disclosed herein can be implemented in or with software in combination with hardware and/or firmware. For example, the subject matter described herein can be implemented in software executed by a processor or processing unit. In an example implementation, the subject matter described herein can be implemented using a computer readable medium having stored thereon computer executable instructions that when executed by a processor of a computer control the computer to perform steps. Example computer readable mediums suitable for implementing the subject matter described herein include non-transitory devices, such as disk memory devices, chip memory devices, programmable logic devices, and application specific integrated circuits. In addition, a computer readable medium that implements the subject matter described herein can be located on a single device or computing platform or can be distributed across multiple devices or computing platforms.

[0104] While at least one example embodiment of the present invention(s) is disclosed herein, it should be understood that modifications, substitutions and alternatives may be apparent to one of ordinary skill in the art and can be made without departing from the scope of this disclosure. This disclosure is intended to cover any adaptations or variations of the example embodiment(s). In addition, in this disclosure, the terms “comprise” or “comprising” do not exclude other elements or steps, the terms “a”, “an” or “one” do not exclude a plural number, and the term “or” means either or both. Furthermore, characteristics or steps which have been described may also be used in combination with other characteristics or steps and in any order unless the disclosure or context suggests otherwise. This disclosure hereby incorporates by reference the complete disclosure of any patent or application from which it claims benefit or priority.