阅读说明：本技术 飞行器失速保护方法和系统 (Aircraft stall protection method and system ) 是由 赵晶慧 高楠 郑晓辉 付琳 邹灿东 吴楠 于 2021-09-02 设计创作，主要内容包括：本公开涉及一种飞行器失速保护方法,包括：确定所述飞行器处于结冰气象条件下；确定所述飞行器的机翼防冰系统的工作状态,所述机翼防冰系统的工作状态至少包括以下各项中的一者或多者：防冰开关的开启或关闭、所述机翼防冰系统是否失效、机翼防冰温度、所述机翼防冰系统的引气活门的开度、所述机翼防冰系统的引气压力；取决于所述机翼防冰系统的不同工作状态,来降低所述飞行器的失速迎角保护值；以及根据经降低的失速迎角保护值来对所述飞行器提供失速保护。(The present disclosure relates to an aircraft stall protection method, comprising: determining that the aircraft is in icing meteorological conditions; determining an operating state of a wing ice protection system of the aircraft, the operating state of the wing ice protection system including at least one or more of: the method comprises the following steps of starting or closing an anti-icing switch, judging whether the wing anti-icing system fails or not, judging the wing anti-icing temperature, the opening degree of a gas-guiding valve of the wing anti-icing system and the gas-guiding pressure of the wing anti-icing system; reducing a stall angle of attack protection value of the aircraft depending on different operating conditions of the wing ice protection system; and providing stall protection to the aircraft in accordance with the reduced stall angle of attack protection value.)

1. An aircraft stall protection method comprising:

determining that the aircraft is in icing meteorological conditions;

determining an operating state of a wing ice protection system of the aircraft, the operating state of the wing ice protection system including at least one or more of: the method comprises the following steps of starting or closing an anti-icing switch, judging whether the wing anti-icing system fails or not, judging the wing anti-icing temperature, the opening degree of a gas-guiding valve of the wing anti-icing system and the gas-guiding pressure of the wing anti-icing system;

reducing a stall angle of attack protection value of the aircraft depending on different operating conditions of the wing ice protection system; and

providing stall protection for the aircraft based on the reduced stall angle of attack protection value.

2. The method of claim 1, wherein determining that the aircraft is in icing meteorological conditions comprises determining that the aircraft is in icing meteorological conditions according to icing conditions defined by an icing detector and/or a flight manual.

3. The method of claim 2, wherein the icing conditions defined by the flight manual comprise:

the temperature measured by the total temperature sensor is below a predetermined temperature threshold and the humidity measured by the humidity sensor is above a predetermined humidity threshold, or

An instruction is received from the pilot to open the wing ice protection system.

4. The method of claim 1, wherein the stall angle of attack protection values for the aircraft include an angle of attack protection onset value and an angle of attack protection maximum value for the aircraft, a stall warning angle of attack value, and an angle of attack platform value.

5. The method of claim 4, wherein the reduced stall angle of attack protection value is decremented in sequence in the event that an anti-icing switch of the wing ice protection system has been turned on but the wing ice protection temperature has not reached the target operating temperature, the anti-icing switch of the wing ice protection system has been turned on and the wing ice protection temperature has reached the target operating temperature, and the wing ice protection system has failed.

6. The method of claim 1, wherein the reduced stall angle of attack protection value is resolved based on a configuration of the aircraft and a current mach number.

7. A method according to claim 6, wherein the configuration of the aircraft comprises at least slat and/or flap skewness.

8. A method according to claim 6, wherein said resolving is performed at a calculation frequency of a flight control computer of said aircraft and/or a sampling frequency of configuration sensors of the aircraft.

9. The method of claim 1, further comprising:

restoring the reduced stall angle of attack protection value of the aircraft to an initial stall angle of attack protection value based on the total temperature being above the predetermined temperature for more than a predetermined period of time and/or a maneuver instruction from the pilot, if an anti-icing switch of the wing anti-icing system has been opened and the wing anti-icing temperature has reached the target operating temperature.

10. The method of claim 1, further comprising:

in the event of failure of the wing anti-icing system, refusing to execute the pilot's instruction to restore the aircraft's stall angle of attack protection value to the initial value.

11. The method of claim 1, further comprising:

the reduced stall angle of attack protection values are provided to EICAS and PFD for use in warning cues.

12. An aircraft stall protection system comprising:

an icing detector for determining that the aircraft is in icing meteorological conditions;

the wing anti-icing system is used for preventing the wing from icing and informing the working state of the wing anti-icing system, and the working state of the wing anti-icing system comprises the following steps: the working state of the wing ice protection system comprises at least one or more of the following: the method comprises the following steps of starting or closing an anti-icing switch, judging whether the wing anti-icing system fails or not, judging the wing anti-icing temperature, the opening degree of a gas-guiding valve of the wing anti-icing system and the gas-guiding pressure of the wing anti-icing system; and

a flight control computer configured to:

determining that the aircraft is in icing meteorological conditions based on the signal from the icing detector;

reducing a stall angle of attack protection value for the aircraft based on the operating conditions received from the wing ice protection system; and

providing stall protection for the aircraft based on the reduced stall angle of attack protection value.

13. The system of claim 12, further comprising a total temperature sensor and/or a humidity sensor for determining that the aircraft is in icy weather conditions.

14. An aircraft comprising a system according to any of claims 12-13.

Technical Field

The present invention relates to the field of flight control laws, and in particular to providing stall protection for aircraft in icing conditions.

Background

After the aircraft enters into an icing meteorological condition, the icing phenomenon of parts such as wings, empennages, airframes, engine air inlet channels and the like can occur. Icing of an aircraft can lead to a reduction in the maximum lift coefficient of the aircraft, control surface efficiency, envelope shrinkage, etc., which in turn has an effect on the stability characteristics and flight safety of the aircraft.

For the telex aircraft with an icing detector and an anti-icing system, the stalling protection control law after icing needs to ensure the flight safety of the aircraft under the icing condition and improve the performance of the aircraft after icing to a certain extent, so that the maneuverability of the aircraft under the icing condition can be improved, and the operation burden of a pilot under the icing condition is relieved.

Therefore, designing a set of protection logic to protect the stall boundary of the aircraft with ice becomes an important problem for the autonomous development of the aircraft (especially telex).

The present disclosure improves upon, but is not limited to, the above factors.

Disclosure of Invention

To this end, the present disclosure provides an aircraft stall protection method and system to effectively stall protect an aircraft in icing conditions.

According to a first aspect of the present disclosure, there is provided an aircraft stall protection method comprising: determining that the aircraft is in icing meteorological conditions; determining an operating state of a wing ice protection system of the aircraft, the operating state of the wing ice protection system including at least one or more of: the method comprises the following steps of starting or closing an anti-icing switch, judging whether the wing anti-icing system fails or not, judging the wing anti-icing temperature, the opening degree of a gas-guiding valve of the wing anti-icing system and the gas-guiding pressure of the wing anti-icing system; reducing a stall angle of attack protection value of the aircraft depending on different operating conditions of the wing ice protection system; and providing stall protection to the aircraft in accordance with the reduced stall angle of attack protection value.

According to an embodiment, determining that the aircraft is in icing meteorological conditions comprises determining that the aircraft is in icing meteorological conditions according to icing conditions defined by an icing detector and/or a flight manual.

According to another embodiment, the icing conditions defined by the flight manual include: the temperature measured by the total temperature sensor is below a predetermined temperature threshold and the humidity measured by the humidity sensor is above a predetermined humidity threshold, or a command from the pilot to open the wing anti-icing system.

According to a further embodiment, the stall angle of attack protection values of the aircraft comprise an angle of attack protection onset value and an angle of attack protection maximum value for the aircraft, a stall warning angle of attack value and an angle of attack platform value.

According to a further embodiment, the reduced stall angle of attack protection value is decremented in sequence in the event that the anti-icing switch of the wing anti-icing system has been opened but the wing anti-icing temperature has not reached the target operating temperature, the anti-icing switch of the wing anti-icing system has been opened and the wing anti-icing temperature has reached the target operating temperature, and the wing anti-icing system fails.

According to a further embodiment, the reduced stall angle of attack protection value is calculated as a function of the configuration of the aircraft and the current mach number.

According to a further embodiment, the configuration of the aircraft comprises at least a slat deflection and/or a flap deflection.

According to a further embodiment, said calculation is performed at the calculation frequency of a flight control computer of said aircraft and/or at the sampling frequency of configuration sensors of the aircraft.

According to a further embodiment, the method further comprises: restoring the reduced stall angle of attack protection value of the aircraft to an initial stall angle of attack protection value based on the total temperature being above the predetermined temperature for more than a predetermined period of time and/or a maneuver instruction from the pilot, if an anti-icing switch of the wing anti-icing system has been opened and the wing anti-icing temperature has reached the target operating temperature.

According to a further embodiment, the method further comprises: in the event of failure of the wing anti-icing system, refusing to execute the pilot's instruction to restore the aircraft's stall angle of attack protection value to the initial value.

According to a further embodiment, the method further comprises: the reduced stall angle of attack protection values are provided to EICAS and PFD for use in warning cues.

According to a second aspect of the present disclosure, there is provided an aircraft stall protection system comprising: an icing detector for determining that the aircraft is in icing meteorological conditions; the wing anti-icing system is used for preventing the wing from icing and informing the working state of the wing anti-icing system, and the working state of the wing anti-icing system comprises the following steps: the working state of the wing ice protection system comprises at least one or more of the following: the method comprises the following steps of starting or closing an anti-icing switch, judging whether the wing anti-icing system fails or not, judging the wing anti-icing temperature, the opening degree of a gas-guiding valve of the wing anti-icing system and the gas-guiding pressure of the wing anti-icing system; and a flight control computer configured to: determining that the aircraft is in icing meteorological conditions based on the signal from the icing detector; reducing a stall angle of attack protection value for the aircraft based on the operating conditions received from the wing ice protection system; and providing stall protection to the aircraft in accordance with the reduced stall angle of attack protection value.

According to an embodiment, the system further comprises a total temperature sensor and/or a humidity sensor for determining that said aircraft is in icing meteorological conditions.

According to a third aspect of the present disclosure, there is provided an aircraft comprising a system according to the second aspect of the present disclosure.

Aspects generally include methods, apparatus, systems, computer program products, and processing systems substantially as described herein with reference to and as illustrated by the accompanying drawings.

The foregoing has outlined rather broadly the features and technical advantages of an example in accordance with the present disclosure in order that the detailed description that follows may be better understood. Additional features and advantages will be described hereinafter. The conception and specific examples disclosed may be readily utilized as a basis for modifying or designing other structures for carrying out the same purposes of the present disclosure. Such equivalent constructions do not depart from the scope of the appended claims. The features of the concepts disclosed herein, both as to their organization and method of operation, together with associated advantages, will be better understood from the following description when considered in connection with the accompanying figures. Each of the figures is provided for the purposes of illustration and description and does not define the limits of the claims.

Drawings

So that the manner in which the above recited features of the present disclosure can be understood in detail, a more particular description of the disclosure, briefly summarized above, may be had by reference to aspects, some of which are illustrated in the appended drawings. It is to be noted, however, that the appended drawings illustrate only certain typical aspects of this disclosure and are therefore not to be considered limiting of its scope, for the description may admit to other equally effective aspects. The same reference numbers in different drawings may identify the same or similar elements.

FIG. 1 is a flow diagram of an example method of aircraft stall protection according to an embodiment of the present disclosure;

FIG. 2 is a block diagram of an example system of aircraft stall protection according to an embodiment of the present disclosure; and

FIG. 3 is a schematic illustration of an aircraft according to an embodiment of the disclosure.

Detailed Description

The detailed description set forth below in connection with the appended drawings is intended as a description of various configurations and is not intended to represent the only configurations in which the concepts described herein may be practiced. The detailed description includes specific details to provide a thorough understanding of the various concepts. It will be apparent, however, to one skilled in the art that these concepts may be practiced without these specific details.

As mentioned above, icing of aircraft (such as icing of wings, tail and fuselage) can affect the handling characteristics and flight safety of the aircraft. The present disclosure provides stall protection of an aircraft after icing for flight safety under icing conditions can be guaranteed, performance of the aircraft after icing can be improved to a certain extent, maneuverability under icing conditions is improved, and pilot operation burden under icing conditions is reduced.

Referring now to FIG. 1, a flowchart of an example method 100 of aircraft stall protection is shown, according to an embodiment of the present disclosure.

At block 110, the method 100 may include determining that the aircraft is in icing meteorological conditions. Generally, an aircraft may experience icing when subjected to icing weather conditions, such as icing of wings, tail wings, fuselage, engine air intakes, and the like.

In one embodiment, the method 100 may determine that the aircraft is in icing meteorological conditions based on an icing detector, such as by an icing signal from an icing detector. It will be appreciated that the aircraft may be provided with more than one icing detector, in which case the aircraft may be determined to be in icing meteorological conditions based on any one or more icing detectors providing icing signals; or any other suitable voting method may be taken to make the decision based on the detection signals of the icing detectors. In another embodiment, the method 100 may determine that the aircraft is in icing meteorological conditions according to icing conditions defined by the flight manual. For example, icing conditions defined by the flight manual may include a total temperature sensor measuring a temperature below a predetermined temperature threshold and a humidity sensor measuring a humidity above a predetermined humidity threshold, receiving an instruction from the pilot to open the wing ice protection system (e.g., the pilot selects to open the wing ice protection system by visual inspection of clouds, moisture, etc.), and so forth. Of course, it will be appreciated by those skilled in the art that any other suitable manner of determining that the aircraft is in icy weather conditions may be used, such as by image processing from images taken by onboard cameras, such as by image processing to determine the presence of clouds.

Next, the method 100 may include determining an operational state of a wing ice protection system of the aircraft at block 120. In this embodiment, the operational state of the wing ice protection system may include at least one or more of: the opening or closing of the anti-icing switch, whether the wing anti-icing system fails or not, the wing anti-icing temperature, the opening of a bleed valve of the wing anti-icing system, the bleed pressure of the wing anti-icing system, and the like.

In one embodiment, the wing ice protection system of the aircraft may be automatically turned on after determining that the aircraft is in icy weather conditions. Alternatively, the wing ice protection system of the aircraft may be turned on based on an on command from the pilot. In this embodiment, after determining that the aircraft is in icy weather conditions, the method 100 may optionally include notifying the pilot to turn on the wing ice protection system, such as displaying an alert, prompt, or the like on an onboard display. In yet another embodiment, the pilot may visualize the visible moisture and manually turn on the wing anti-icing system based on the measured temperature of the total temperature sensor. It will be appreciated by those skilled in the art that any other suitable means may be used to open the wing ice protection system. After the wing ice protection system is turned on, the method 100 may determine the operating state of the wing ice protection system according to a signal from the wing ice protection system (such as turning on or off an ice protection switch, whether the wing ice protection system is disabled, a wing ice protection temperature, an opening degree of a bleed valve of the wing ice protection system, a bleed pressure of the wing ice protection system, and the like), which is not described herein again.

Subsequently at block 130, method 100 may include reducing a stall angle of attack protection value for the aircraft depending on different operating conditions of the wing ice protection system.

The inventors have realized that after an aircraft is iced, the angle of attack of the aircraft is lost in order to avoid stalling. Thus, in one embodiment, the stall angle of attack protection value of the aircraft needs to be reduced. In yet another embodiment of the present disclosure, the stall angle of attack protection values for an aircraft may include an angle of attack protection onset value and an angle of attack protection maximum value for the aircraft, a stall warning angle of attack value, and an angle of attack platform value, among others. Thus, the method 100 may reduce any one or more of these values depending on the different operating conditions of the wing ice protection system to effectively ensure flight safety under icing conditions and improve the ice-on-aircraft performance.

In a preferred embodiment, the reduced stall angle of attack protection value is calculated based on the configuration of the aircraft and the current mach number, wherein the configuration of the aircraft includes at least a slat deflection and/or a flap deflection. Continuing with the above example, this calculation may use Mach number, slat skewness, flap skewness, etc. as parameters to look up the reduced stall angle-of-attack protection value for this combination of parameters from the table. In a further embodiment, since the initial stall angle of attack protection value of the aircraft (i.e. the angle of attack protection value provided by its stall protection system in ice-free conditions) is known, the corresponding look-up table may also record the difference from the initial stall angle of attack protection value, so that the reduced stall angle of attack protection value is obtained by subtracting the difference from the initial stall angle of attack protection value.

For example, based on different states of the wing anti-icing system (e.g., three different states including an anti-icing switch of the wing anti-icing system being turned on but the wing anti-icing temperature not reaching the target operating temperature (mainly applicable to the takeoff phase and the short-time cloud-through situation of the aircraft), an anti-icing switch of the wing anti-icing system being turned on and the wing anti-icing temperature reaching the target operating temperature (mainly applicable to the standby phase and the approach landing phase of the aircraft), and a wing anti-icing system failure (mainly applicable to the standby phase and the approach landing after the anti-icing system failure)), and stall angle-of-attack protection values (e.g., four stall angle-of-attack protection values including an initial value and a maximum value of angle-of-attack protection of the aircraft, a warning stall angle-of-attack value and a platform value), there may be twelve look-up tables, one for each stall angle of attack protection value for different states of the wing ice protection system. Thus, the method 100 may select a corresponding look-up table based on different operating states of the wing ice protection system when the aircraft is in icy weather conditions, and use the aircraft's mach number, slat skewness, flap skewness, etc. to find a suitable reduced stall angle of attack protection value in the selected look-up table. It will be appreciated by those skilled in the art that the twelve lookup tables given above are merely preferred examples of the present disclosure, and any one or more of the opening or closing of the anti-icing switch, whether the wing anti-icing system is disabled, the wing anti-icing temperature, the opening of the bleed valve of the wing anti-icing system, the bleed air pressure of the wing anti-icing system, and the like may correspond to one lookup table. Of course, although the present disclosure describes using a lookup table to find a suitable stall angle of attack protection value, it will be appreciated that any other suitable manner, such as calculation in real time, may be employed.

In another embodiment, the resolution of the reduced stall angle of attack protection value is performed at the frequency of calculation by the aircraft's flight control computer and/or the frequency of sampling by the aircraft's configuration sensors. Thus, the reduced stall angle of attack protection value may be updated in real time depending on the operating state of the wing ice protection system of the aircraft, mach number, slat skewness, flap skewness, and the like.

Further in accordance with the above preferred embodiment, the reduced stall angle of attack protection value is decremented in sequence when the anti-icing switch of the wing anti-icing system is turned on but the wing anti-icing temperature has not reached the target operating temperature, the anti-icing switch of the wing anti-icing system is turned on and the wing anti-icing temperature has reached the target operating temperature, and the wing anti-icing system is disabled. Therefore, when the anti-icing switch of the wing anti-icing system is turned on but the wing anti-icing temperature does not reach the target working temperature, the incidence angle loss of the aircraft is minimum; the loss of angle of attack of the aircraft is greatest when the wing anti-icing system fails. This allows the performance (e.g. maneuverability) of the aircraft to be maximised whilst ensuring flight safety.

Taking an initial value of the angle of attack protection and a maximum value of the angle of attack protection as examples: under the condition that the wing anti-icing system is started but does not reach the target working temperature (namely, an anti-icing switch of the wing anti-icing system is started but the wing anti-icing temperature does not reach the target working temperature), subtracting the first value from the initial value of the attack angle protection to obtain a reduced initial value of the attack angle protection, and subtracting the second value from the maximum value of the attack angle protection to obtain a reduced maximum value of the attack angle protection; subtracting the initial value of the angle of attack protection to obtain a reduced initial value of the angle of attack protection and subtracting a fourth value from the maximum value of the angle of attack protection to obtain a reduced maximum value of the angle of attack protection when the ice protection system of the wing has reached the target working temperature (namely, an anti-icing switch of the ice protection system of the wing is turned on and the ice protection temperature of the wing has reached the target working temperature); and under the condition that the anti-icing system of the wing fails, subtracting the fifth value from the initial value of the angle of attack protection to obtain a reduced initial value of the angle of attack protection, and subtracting the sixth value from the maximum value of the angle of attack protection to obtain a reduced maximum value of the angle of attack protection. In this particular example, the first value is less than the third value and the third value is less than the fifth value; and the second value is less than the fourth value and the fourth value is less than the sixth value; and the first and second values may be the same or different, the third and fourth values may be the same or different, and the fifth and sixth values may be the same or different. Those skilled in the art will appreciate that the same principles may be applied to stall warning angle of attack values, angle of attack platform values, and other stall angle of attack protection values.

Subsequently, at block 140, method 100 may include providing stall protection for the aircraft based on the reduced stall angle of attack protection value. The stall protection control laws for aircraft are known to those skilled in the art and are therefore not described in detail here.

In another embodiment of the present disclosure, optionally, the method 100 may further include returning the reduced stall angle of attack protection value of the aircraft to the initial stall angle of attack protection value based on the total temperature being greater than the predetermined temperature for more than a predetermined period of time and/or a maneuver instruction from the pilot if an anti-icing switch of the wing anti-icing system has been opened and the wing anti-icing temperature has reached the target operating temperature. For example, a pilot may visually find that the aircraft is ice free, and may manually turn off the wing ice protection system; in this case, method 100 may terminate and the reduced stall angle-of-attack protection value may be restored such that there is no loss of any angle-of-attack, resulting in restoration of the aircraft's maneuverability as early as possible. It will be appreciated by those skilled in the art that any other suitable parameters and instructions may be used to cause the stall angle of attack protection value of the aircraft to be restored.

In a further embodiment of the present disclosure, to ensure flight safety, the angle of attack boundary of the aircraft should be limited in the event of the aircraft being iced. Thus, method 100 may also optionally include denying execution of an instruction by the pilot to restore the stall angle of attack protection value of the aircraft to the initial value in the event of a failure of the anti-icing system of the wing. This is because, in the event that the aircraft is in icy weather conditions and the wing ice protection system fails, the aircraft wings, fuselage, etc. all freeze (i.e., become iced), and thus the stall angle of attack protection value for the aircraft should be reduced to ensure flight safety. Thus, in this situation, even if the pilot were instructed to restore the stall angle of attack protection value, the method 100 may refuse to execute this instruction, and continue to maintain application of the reduced stall angle of attack protection value.

In yet another embodiment of the present disclosure, the method 100 may further include providing the reduced stall angle of attack protection value to an EICAS (engine indication and crew warning system) and a PFD (primary flight display) for use in alerting the pilot.

Referring next to FIG. 2, a block diagram of an example system 200 for aircraft stall protection is shown, according to an embodiment of the present disclosure.

As shown in fig. 2, aircraft stall protection system 200 may include an icing detector 210, a wing anti-icing system 220, and a flight control computer 230, where icing detector 210 is configured to determine that the aircraft is in an icing meteorological condition and transmit a corresponding signal to flight control computer 230, wing anti-icing system 220 is configured to prevent wing icing and notify its operational status (e.g., to flight control computer 230), and flight control computer 230 may be configured to determine that the aircraft is in an icing meteorological condition based on the signal from icing detector 210, and to reduce the stall angle of attack protection value of the aircraft based on the operational status received from wing anti-icing system 220; and providing stall protection for the aircraft based on the reduced stall angle of attack protection value.

As shown in fig. 2, flight control computer 230 may output the calculated reduced stall angle of attack protection value, e.g., to an onboard display for display, etc.

Optionally, aircraft stall protection system 200 may also include a total temperature sensor and/or a humidity sensor for determining that the aircraft is in icy weather conditions. In this embodiment, it may be determined that the aircraft is in icing meteorological conditions where the temperature measured by the total temperature sensor is below a predetermined temperature threshold and the humidity measured by the humidity sensor is above a predetermined humidity threshold. Here, the predetermined temperature threshold and the predetermined humidity threshold may be any suitable predetermined values.

Fig. 3 is a schematic diagram illustrating an example aircraft 300, according to aspects of the present disclosure. As shown, the aircraft 300 may include an aircraft stall protection system 310, such as the example aircraft stall protection system 200 described in FIG. 2.

Thus, the present disclosure provides stall protection for all icing scenarios after an aircraft is iced. The stall attack angle protection value sets different attack angle losses according to different ice-carrying scenes, so that the attack angle losses are gradually increased along with the increase of the ice-carrying, the performance loss caused by the rapid change of the attack angle from ice-free to ice-carrying is prevented under the condition that the flight safety under the icing condition is effectively ensured, and the performance of the aircraft after the ice-carrying is ensured.

The foregoing detailed description includes references to the accompanying drawings, which form a part hereof. The drawings illustrate by way of illustration specific embodiments that can be practiced. These embodiments are also referred to herein as "examples". Such examples may include elements other than those illustrated or described. However, examples including the elements shown or described are also contemplated. Moreover, it is contemplated to use the examples shown or described with any combination or permutation of those elements, or with reference to a particular example (or one or more aspects thereof) shown or described herein, or with reference to other examples (or one or more aspects thereof) shown or described herein.

In the appended claims, the terms "comprises," "comprising," and "includes" are open-ended, that is, a system, device, article, or process that includes elements in the claims other than those elements recited after such terms is considered to be within the scope of that claim. Furthermore, in the appended claims, the terms "first," "second," and "third," etc. are used merely as labels, and are not intended to indicate a numerical order of their objects.

In addition, the order of operations illustrated in this specification is exemplary. In alternative embodiments, the operations may be performed in a different order than illustrated in the figures, and the operations may be combined into a single operation or split into additional operations.

The above description is intended to be illustrative, and not restrictive. For example, the above-described examples (or one or more aspects thereof) may be used in conjunction with other embodiments. Other embodiments may be used, such as by one of ordinary skill in the art, after reviewing the above description. The abstract allows the reader to quickly ascertain the nature of the technical disclosure. This Abstract is submitted with the understanding that it will not be used to interpret or limit the scope or meaning of the claims. Furthermore, in the foregoing detailed description, various features may be grouped together to streamline the disclosure. However, the claims may not recite every feature disclosed herein because embodiments may characterize a subset of the features. Moreover, embodiments may include fewer features than are disclosed in a particular example. Thus the following claims are hereby incorporated into the detailed description, with one claim standing on its own as a separate embodiment. The scope of the embodiments disclosed herein should be determined with reference to the appended claims, along with the full scope of equivalents to which such claims are entitled.