Patent Publication Number: US-9834417-B2

Title: Payload control apparatus, method, and applications

Description:
BACKGROUND OF THE INVENTION 
     Field of the Invention 
     Embodiments of the invention are generally in the field of controlling and/or positioning a physical payload in an unstable medium (e.g., air, water) and, more particularly relate to a method and apparatus for controlling and/or positioning a payload in an unstable medium and compensating for heave or other uncontrolled motion induced by the medium, (e.g., marine wave action), and applications thereof. 
     Description of Related Art 
     Heave compensation refers generally to systems that adjust for or otherwise compensate for the motion of a surface ship on equipment suspended overboard in a water column, lifted or lowered through the water column, and or landed on the ocean bottom, a surface platform or dock, or another vessel. In all these cases, the motion of the surface ship induced by wave action acting on it are substantially conveyed, or in some cases amplified and conveyed, to payloads suspended from the ship by rope, cable, chain, belt or similar connecting medium whether flexible or rigid. 
       FIGS. 1 and 2  illustrate examples of the problem heave compensation systems are intended to address. A surface ship  1  having a deck  10  floats above a surface of a body of water indicated by a waterline  2 . The deck  10  is elevated above the waterline  2  and machinery is affixed to it. A crane  40  or similar lifting mechanism is configured so as to be able to lift overboard a payload  60  and raise or lower that payload  60  by rope or cable  30  connected on one end to the payload  60  and on the other end to a winch  20 . The cable  30  passes over an overboard-sheave  50  where the direction of the cable  30  is changed from near horizontal to vertical. When at rest, the tension in cable  30  is nominally equal to the weight of the payload  60  plus the weight of the cable  30  between overboard-sheave  50  and payload  60 . 
     In  FIG. 2 , the ship  1  is raised by wave action above a reference line  100  which it was earlier below as shown in  FIG. 1 . This happens over a finite period of time wherein the ship  1 , and more specifically, the overboard-sheave  50 , is accelerated upward. The ship  1  resists this acceleration by settling deeper in the water as indicated by the waterline  2  nearer the deck. The payload  60  also resists this acceleration because of gravity acting on its own mass plus the drag force of the water acting on the payload  60  once in motion. The tension in cable  30  is thereby increased until the vertical velocity of the payload  60  is equal to or exceeds the velocity of overboard-sheave  50 . The increased tension in cable  30  can be extreme and introduces loads on all components of the system including the deck  10 , the winch  20 , the crane  40 , the overboard-sheave  50 , as well as the payload  60 . The entire system must be engineered to withstand the forces that will act on it given a particular sea state defining the safe operating window; otherwise, one or another system component will fail, endangering the mission, equipment, personnel, and/or payload. 
     When the upward motion of the ship  1  decelerates and subsequently begins to fall back to or through its starting position, all the forces and tensions are reduced but the danger of a mechanical failure is not gone, just delayed until that motion stops. The same drag forces on the payload  60  that worked with gravity to resist its upward movement also act against the payload  60  falling as quickly as gravity alone would cause it to fall. It is in fact possible that overboard-sheave  50  may fall more quickly than the payload  60 . This would allow tension in the cable  30  to fall to zero and slack to accumulate in one or more portions of cable  30 . In this circumstance the payload  60  is accelerating downward resisted only by its drag in the water and not from any tension earlier supporting it from above by the cable  30 . When the downward motion of overboard-sheave  50  ends and is subsequently reversed, the cable  30  will come taut in a “snap load” event. Snap loads can easily exceed the breaking strength of cable  30  and/or the rated operational capacity of other mechanical components of the system. Breakage of the cable  30  and/or damage to other components of the system may result in loss of the payload  60 , loss of time and money, as well as cause injury or death. 
     Heave may be defined as the vertical motion of the overboard-sheave  50  induced by wave action on the vessel, and heave compensation systems are employed to minimize the effects described above thereby widening the safe operating window for the vessel and its machinery in carrying out its mission. 
       FIG. 3  illustrates a conventional example of a passive heave compensation system that is entirely spring based. It is passive because once engaged, it requires no extra energy beyond the energy introduced into the system by the motion of the ship and payloads themselves. Deck  10 , winch  20 , cable  30 , overboard-sheave  50 , and payload  60  are as illustrated in earlier figures. Overboard-sheave  50  is supported by crane  40  (not shown) as before. Two sheave-blocks  70  and  80  are separated from each other by a spring  90 . Sheave block  70  is fixed in place, and may be referred to as a “fixed sheave-block”, while sheave-block  80  is movable, and may be referred to as a “flying sheave-block”. The flying sheave-block  80  optionally moves vertically inside a support structure (not shown) that keep it stably centered over the fixed sheave-block  70 . As illustrated, the spring  90  is substantially vertically oriented with sheave-blocks  70 ,  80  aligned one above the other, but horizontal arrangements are possible and common. Cable  30 , which in earlier figures passed from winch  20  directly over overboard-sheave  50 , instead first makes a complete path around both the fixed sheave-block  70  and the flying sheave-block  80  before making its way over the overboard-sheave  50 . One complete path around both sheave-blocks  70 ,  80  is illustrated but multiple passes, typically 2 (mechanical advantage of 4), are often employed so that shorter excursions of the flying sheave-block  80  can accommodate longer heave excursions at the expense of a stronger spring. Other sheave arrangements are possible and easily comprehended by those skilled in the art. 
       FIG. 3A  shows the reaction of machinery in  FIG. 2  to an upward heave event. The upward heave A increases tension on the cable  30  and causes the spring to be compressed, reducing the distance between the sheave-blocks B, and freeing some portion of cable  30  that passes around the sheave-blocks to be released as illustrated. During a downward heave event A shown in  FIG. 3B , reduced tension on the cable  30  will allow the spring to expand, increasing the distance between the sheave-blocks B, which in turn takes up what might otherwise be slack in rope  30 . One can see that the spring constant must be matched to the load, which includes the payload  60  plus the weight of cable  30  between overboard-sheave  50  and the payload  60 . If friction is ignored, the passive system just described is closely analogous to a spring  70  inserted in rope  30  between overboard-sheave  50  and the payload as illustrated in  FIG. 4 . 
     In practice, it is not practical to change coil springs based on the mass of the load being handled. Springs in passive heave systems as described are instead “gas springs,” and the typical components are illustrated in  FIG. 5 . A gas spring  200  consists of a piston  210  free to move inside a piston housing  220 , with a bottom seal  230 . The piston has seals  211  that prevent gas from passing between the piston  210  and piston housing  220 . At the bottom of the piston housing  220  there is plumbing that allows gas to pass freely between the piston assembly  239  and an accumulator  240 . The volume inside the piston housing  220  below the piston seals  211  together with volume inside the accumulator  240  constitutes a pressure vessel. The volume of the pressure vessel is further increased by plumbing in a series of gas bottles  250 . The gas is typically nitrogen or air, but other gases may be utilized. As the piston  210  is advanced into the piston housing  220 , the gas beneath the seals  211  is displaced and therefore compressed uniformly inside all the components making up the pressure vessel. Neglecting well understood details regarding temperature and non ideal gases, the spring constant of the system is adjusted by varying the pressure inside the gas filled portion of the gas spring  200  relying on Boyles Law, where pressure p multiplied by volume v is a constant. The fully pneumatic spring of  FIG. 5  represents a passive heave spring but typically a combination gas-over-fluid spring, as illustrated in  FIG. 6  is used for reasons unimportant to this discussion. In such springs, the piston housing  220  is filled with fluid  241  beneath the piston seals  211 , as is a substantial portion of the accumulator  242  and the plumbing  235  connecting the two. When the piston  210  is advanced into the piston housing  220 , instead of compressing gas directly, it displaces hydraulic fluid into the bottom of the accumulator. The gas-fluid interface  243  is inside the accumulator  240 . As the level of fluid in the accumulator  240  is increased, it compresses the gas in the upper portion of the accumulator  240  and the remainder of the pressure vessel in just the same manner that the piston itself would in the all pneumatic version of  FIG. 5 . 
     The spring constant in a gas spring is easily adjusted by changing the pressure in the pressure vessel. 
       FIG. 7  shows the principle components of a gas spring in a passive heave compensation system as discussed. The system illustrated and discussed herein above had a single pneumatic or hydraulic piston, but there can be more than one piston (often two) between the flying sheave-block  80  and the fixed sheave-block  70  usually feeding the same accumulator  240 . 
     Passive heave compensation systems based on gas springs are widely used, simple, and very effective at insulating cable  30  from extreme fluctuations in tension. However the spring only responds to changes in the tension of rope  30  at the overboard sheave  50 , and any change in this tension will cause the payload  60  to be displaced vertically in the water column. That tension is nominally equal to the weight in water of the payload  60  plus the weight in water of the rope  30  between the overboard sheave  50  and the payload  60 . This can be defined as “active-load” and is a largely invariant physical property of payload  60 , rope  30 , and the earth&#39;s gravity. Absent heave, the weight-on-sheave (WOS) at the overboard sheave  50  will nominally be equal to the active-load. However, the WOS is sensitive to heave due to the payload&#39;s inertia and the drag forces acting on the payload  60  and rope  30 . If the WOS at overboard sheave  50  exceeds the active-load, the payload  60  will be lifted in the water column. And if the WOS at overboard sheave  50  is below the active-load, the payload  60  will fall in the water column. 
     In addition, the spring cannot respond until the differential tension is sufficient to overcome the friction in the system components, which can be significant. There is substantial friction a) between the seals  211  and the piston housing, b) in the sheaves turning on their shafts, which is increased with increased active-load, and c) between the flying sheave-block and its support structure (if used; not shown) that constrain its motion. Added to the friction in the machinery, cable  30  is likely a relatively large wire rope, synthetic rope, or armor shielded umbilical. Such ropes and cables do not bend easily over a sheave and once bent, resist counter deformation. Added to this is the inertia in all of the massive metal moving parts, which resist being set in motion in the first place, but are particularly resentful of changing direction. Finally, the spring stored energy will be recovered when the heave action is decelerated or reversed. Transmissibility is a well understood property of springs, is frequency sensitive, and is defined as the ratio between output and input amplitude of the spring. 
     For all of these reasons spring based passive systems are deficient at maintaining a payload  60  stationary in the water column. 
     When residual motion of the payload  60  is too extreme for the particular mission&#39;s purpose, active heave compensation must be employed. Active systems directly control the pay-out and take-up of cable  30  passing over the overboard sheave  50  and/or the elevation of the overboard sheave  50  so as to ideally compensate for the motion of the ship  1 , limited principally by the ability to measure and anticipate that motion. Measurement and forecast is typically left to a motion reference unit (MRU) composed of computer, software, and input from various sensors. These systems are complicated and expensive, but even if perfect at measuring and predicting the motion, making real time adjustments in these physical systems (winch  20  start, stop, reverse ( FIG. 8 )/sheave elevation/crane  40  adjustments ( FIG. 9 )) typically require substantial additional power (hydraulic or electric) and substantial strengthening of associated machinery, further increasing the cost. 
     There are active systems that incorporate passive systems as described hereinabove. In these cases, the active system provides power assist (usually hydraulic) to override the motion of the flying sheave-block  80 . Such systems are called active-over-passive (AOP) systems as diagramed in  FIGS. 10 and 11 .  FIG. 10  is different diagrammatically but operationally identical to passive gas-spring compensation systems as already discussed.  FIGS. 11 and 12  show the addition of a hydraulically implemented active override  300 . One can see why these systems need little added power: the spring is doing the lion&#39;s share of the work just as it did acting alone passively. The only extra force required is that needed to overcome friction in the system, the energy stored in the spring when displaced from its neutral set-point, and the inertia in the moving parts. 
       FIG. 13  shows a block diagram of the active-over-passive system described. The motion of the vessel is monitored by a motion reference unit (MRU). The motion at the over-boarding sheave and the adjustments necessary to compensate for this are computed in a computer or a programmable logic controller (PLC) from the data provided by the MRU. The PLC then directs hydraulic fluid to actuate the hydraulic cylinder in the appropriate direction. The actual motion is fed back to the PLC from a measuring device. The active portion of the system as described is implemented with a hydraulic cylinder but those skilled in the art will recognize other mechanisms could be used to add the necessary energy, such as, e.g., a motor driving a rack and pinion. 
       FIG. 14  depicts another shortcoming with gas-spring compensation systems, whether active or passive. The lift line carrying the payload being compensated traverses all the sheaves of the gas spring. This is true not just when compensating, but for the entire ascent and descent from the vessel to the final operating depth. At each sheave the rope or wire bends over that sheave causing wear. We refer to this as “inline compensation,” and all inline compensators are bend-over-sheave (BOS) multipliers. The lift line, whether wire or new synthetic fiber, may be three or more miles long in marine operations, for example, and cost in excess of $150,000; thus wear and deterioration of the rope is a serious matter even without considering the value of the payload connected to the vessel by this single thread. It is also difficult to monitor the condition of the rope over its entire length during routine operations. 
     For all of the aforementioned reasons there exists a need for a low power payload control apparatus and heave compensation systems (active or passive) and associated methods in which the heave-compensated load line is not required to traverse the sheaves of the gas-spring doing most of the work. 
     SUMMARY 
     An embodiment of the invention is a payload control apparatus that includes a spring-line assembly, including a spring line actuating mechanism, a spring-line flying sheave assembly including at least a flying sheave over which a load line can pass, and a spring line having one end connected to the spring line actuating mechanism and another end connected to the spring line flying sheave assembly, wherein the spring line flying sheave assembly can be moveably disposed via the spring line actuating mechanism into at least one position such that the flying sheave is in either a non-contacting, spaced relation or a non-path-altering, contacting relation to a region of the load line having a straight load-line path length, L 1 , in local proximity to the flying sheave, wherein the load-line is connected at one region thereof to a winch assembly and at another region thereof to a payload to be controllably lifted, lowered, positioned, or maintained in a stationary location, further wherein the spring-line flying sheave assembly can be moveably disposed via the actuating mechanism into at least another position such that the flying sheave is in engaging contact with the load-line region in proximity to the flying sheave in a manner that alters the straight load-line path length, L 1 , such that the altered load-line path is not straight and has a path length, L 2 , that is greater than L 1 . It is to be clear to the reader that the length of the load line between the winch and the payload does not change regardless of the heaving motion of the vessel; rather, according to the invention, the path of the load line between the winch and the payload is changed by the displacement of the flying sheave. Thus, for illustration, when the vessel falls in a heave event that would otherwise cause the payload to fall as well, the flying sheave will act to increase the path length local to the flying sheave traversed by the load line therein causing a shortening of the path length subsequent to the flying sheave thereby preventing the payload from falling. In various non-limiting aspects, the payload control apparatus may further include or be further characterized by the following features or limitations:
         wherein the spring line is a rigid medium;   wherein the spring line is a flexible medium;
           wherein the spring line is one of a rope and a cable;   
           wherein the load and at least a portion of the load-line are disposed in a water column;   further comprising one or more rotatable, positionally fixed sheaves disposed in the load-line path in contact with or contactable with the load line, whereby the one or more fixed sheaves provide load-line path stabilization when the spring-line assembly flying sheave is disposed in the path-altering, engaging contact position with the load-line;   wherein ΔL=L 2 −L 1  is controllably variable;   wherein the spring-line assembly further comprises a spring line flying sheave assembly guiding structure providing a flying sheave assembly path within which the spring-line assembly flying sheave is moveably disposed so as to direct the motion of the flying sheave along the sheave path;
           further comprising an active compensator operably coupled to the guiding structure and the spring-line assembly sheave;
               wherein the active compensator includes a motion feedback control component and at least one of a motorized rack and pinion assembly, a hydraulic cylinder, a pneumatic cylinder, a third driven line, a traction winch, or the like;   
               
           wherein the spring line actuating mechanism includes a spring and at least one rotatable and movable sheave acted on by the spring.
           wherein the spring is a pneumatic spring;   wherein the spring is a hydro-pneumatic spring;   
           wherein the spring line actuating mechanism includes a passive heave compensation device of any form;   wherein the one end of the spring line is affixed to the spring line actuating mechanism;
           wherein the one end of the spring line is affixed to the at least one movable sheave of the spring line actuating mechanism.   
               

     An embodiment of the invention is a method for controlling a payload that is desired to be raised, lowered, positioned, or maintained in a position in an unstable medium. The method includes the steps of providing a payload attached to a load-line having a locally straight load-line path and providing a payload control apparatus as described hereinabove; and utilizing the payload control apparatus stabilize the payload in the unstable medium. According to an aspect, the unstable medium is water. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIGS. 1-14  are diagrams illustrative of the current state of the technology and the shortcomings thereof; 
         FIG. 15  is a drawing that schematically illustrates a payload control apparatus in an unengaged state, according to an embodiment of the invention; 
         FIG. 16  is a drawing that schematically illustrates the payload control apparatus shown in  FIG. 15  in an engaged state, according to an aspect of the invention; 
         FIG. 17  diagrammatically illustrates a payload control apparatus in an engaged states according to an illustrative embodiment of the invention; 
         FIG. 18  diagrammatically illustrates the locally straight unaltered path l 1  of length L 1  and the lengthened path l 2  of length L 2  when the apparatus is engaged according to an illustrative embodiment of the invention; 
         FIG. 19  shows a flying sheave assembly portion of the payload control apparatus of  FIG. 17  in an unengaged state; 
         FIG. 20  shows the flying sheave assembly portion of the payload control apparatus of  FIG. 19  in an engaged state; 
         FIG. 21  shows an active compensation component of the flying sheave assembly, according to an aspect of the invention; and 
         FIGS. 22, 23, 24, 25  respectively show block and tackle diagrams that illustrate different mechanical advantages that can be designed into the embodied invention. 
     
    
    
     DETAILED DESCRIPTION OF NON-LIMITING, EXEMPLARY EMBODIMENTS OF THE INVENTION 
     An embodiment of a payload control apparatus  1000  is illustrated in  FIG. 15 . In the aspect shown, the apparatus is in an unengaged state. Although a winch  1020 , load  1060 , and an upper deck and main deck of a marine vessel are illustrated, they do not form a part of the invention per se; rather, they assist in illustrating the operation of the invention. 
     The apparatus  1000  includes a spring-line assembly  1002 , including a spring line actuating mechanism  1005 , a spring-line flying sheave assembly  1006  including at least a flying sheave  1006 - 1  over which a load line ( 1030 ) can pass; and a spring line  1004  having a second end  1004 - 2  connected to the spring line actuating mechanism and a first end  1004 - 1  connected to the spring line flying sheave assembly  1006 . The spring line flying sheave assembly  1006  can be moveably disposed via the spring line actuating mechanism into at least one position such that the flying sheave  1006 - 1  is either in a non-contacting, spaced relation with a section of the load line  1030  (see  FIG. 15 ) or in a non-path-altering, contacting relation to a region of a straight load-line path having a length L 1  ( FIGS. 18 and 19 ) of the load-line that is connected at a second end thereof to the winch assembly  1020  and at another region (first end) thereof to the payload  1060  to be controllably lifted, lowered, positioned, or maintained in a stationary location. The spring-line flying sheave assembly  1006  further can be moveably disposed via the actuating mechanism into at least another position such that the flying sheave  1006 - 1  is in a path-altering, engaging contact position (see  FIG. 16 ) with the region of the straight load-line path of the load-line (also  FIGS. 18 and 20 ) such that the load-line path is not straight and has a local load line path length L 2  that is greater than load line path length L 1 . It is to be clear to the reader that the length of the load line between the winch and the payload does not change regardless of the heaving motion of the vessel; rather, according to the invention, the path of the load line between the winch and the payload is changed by the displacement of the flying sheave.  FIG. 16  shows a heave event where the vessel fell by a distance D and the load was adjusted by an equal amount ΔL=L 2 −L 1  thereby holding the payload  1060  steady in the water column. 
       FIGS. 17-21  illustrate particular detailed aspects of an exemplary embodiment of the invention. Referring to  FIGS. 17 and 21 , the spring-line assembly  1002  includes a spring line actuating mechanism  1005  in the form of a gas spring  1008 , which includes fixed and moveable sheaves separated by the spring  1008  (pneumatic, hydra-pneumatic, etc.). The figures further illustrate a flying sheave assembly guiding member  1070  within which the flying sheave assembly  1006  (and the connected flying sheave  1006 - 1 ) can controllably move in a linear direction. Referring to  FIG. 19 , fixed sheaves  1090  may, but need not be in operational contact with the load line  1030  when the apparatus is unengaged and non-path-altering. 
     It is to be appreciated that while the foregoing description of the embodied invention utilizes a spring line in the form of a rope or cable; i.e., a flexible spring line medium, the spring line  1004  as depicted in  FIGS. 15 and 16  could comprise a rigid, inflexible medium such as, e.g., a rod, bar, or pole that can be used to move the flying sheave between a load line path-altering and load line non-path-altering positions. As such, the embodied payload control apparatus need not have a spring line actuating mechanism that includes a gas spring or equivalent component; rather, a flying sheave movably disposed by actuating machinery will be sufficient. 
     As further shown in  FIG. 21 , the flying sheave assembly may include an active compensator assembly  1080  operably coupled to the guiding structure and the spring-line flying sheave assembly. The active compensator includes a motion feedback control component of sensors and computational devices (not shown) controlling the motorized rack and pinion assembly  1080 . The active compensator may also or alternatively comprise a hydraulic cylinder, a pneumatic cylinder, or a third driven line (not shown) to assist the motion of the flying sheave. 
     Advantageously, the spring line actuating machinery  1005  (e.g., gas spring  1008 ) may be oriented as needed or convenient anywhere on the vessel. Moreover, the spring line can have a nominal length of less than 200 feet, since it need only be long enough to extend from the flying sheave assembly  1006  and about the actuating machinery to compensate for gross heave distances in the unstable medium. As such, the spring line can be easily inspected and replaced if necessary, and be made arbitrarily strong. Most advantageously, the relatively long, heavy, expensive, and unwieldy load line is not required to, and does not traverse the sheaves of the gas-spring  1008  doing most of the heave compensation work. 
     As illustrated in  FIGS. 22-25  and as will readily be appreciated by those skilled in the art, the spring line actuating mechanism (e.g., gas spring) can be designed to have an Nx mechanical advantage, N=3, 4, 5, 6, respectively, and the arrangement of components including added optional fixed sheaves  1090  is nearly limitless. 
     While several inventive embodiments have been described and illustrated herein, those of ordinary skill in the art will readily envision a variety of other means and/or structures for performing the function and/or obtaining the results and/or one or more of the advantages described herein, and each of such variations and/or modifications is deemed to be within the scope of the inventive embodiments described herein. More generally, those skilled in the art will readily appreciate that all parameters, dimensions, materials, and configurations described herein are meant to be exemplary and that the actual parameters, dimensions, materials, and/or configurations will depend upon the specific application or applications for which the inventive teachings is/are used. Those skilled in the art will recognize, or be able to ascertain using no more than routine experimentation, many equivalents to the specific inventive embodiments described herein. It is, therefore, to be understood that the foregoing embodiments are presented by way of example only and that, within the scope of the appended claims and equivalents thereto, inventive embodiments may be practiced otherwise than as specifically described and claimed. Inventive embodiments of the present disclosure are directed to each individual feature, system, article, material, kit, and/or method described herein. In addition, any combination of two or more such features, systems, articles, materials, kits, and/or methods, if such features, systems, articles, materials, kits, and/or methods are not mutually inconsistent, is included within the inventive scope of the present disclosure. 
     All definitions, as defined and used herein, should be understood to control over dictionary definitions, definitions in documents incorporated by reference, and/or ordinary meanings of the defined terms. 
     The indefinite articles “a” and “an,” as used herein in the specification and in the claims, unless clearly indicated to the contrary, should be understood to mean “at least one.” 
     The phrase “and/or,” as used herein in the specification and in the claims, should be understood to mean “either or both” of the elements so conjoined, i.e., elements that are conjunctively present in some cases and disjunctively present in other cases. Multiple elements listed with “and/or” should be construed in the same fashion, i.e., “one or more” of the elements so conjoined. Other elements may optionally be present other than the elements specifically identified by the “and/or” clause, whether related or unrelated to those elements specifically identified. Thus, as a non-limiting example, a reference to “A and/or B”, when used in conjunction with open-ended language such as “comprising” can refer, in one embodiment, to A only (optionally including elements other than B); in another embodiment, to B only (optionally including elements other than A); in yet another embodiment, to both A and B (optionally including other elements); etc. 
     As used herein in the specification and in the claims, “or” should be understood to have the same meaning as “and/or” as defined above. For example, when separating items in a list, “or” or “and/or” shall be interpreted as being inclusive, i.e., the inclusion of at least one, but also including more than one, of a number or list of elements, and, optionally, additional unlisted items. Only terms clearly indicated to the contrary, such as “only one of” or “exactly one of,” or, when used in the claims, “consisting of,” will refer to the inclusion of exactly one element of a number or list of elements. In general, the term “or” as used herein shall only be interpreted as indicating exclusive alternatives (i.e. “one or the other but not both”) when preceded by terms of exclusivity, such as “either,” “one of,” “only one of,” or “exactly one of.” “Consisting essentially of,” when used in the claims, shall have its ordinary meaning as used in the field of patent law. 
     As used herein in the specification and in the claims, the phrase “at least one,” in reference to a list of one or more elements, should be understood to mean at least one element selected from any one or more of the elements in the list of elements, but not necessarily including at least one of each and every element specifically listed within the list of elements and not excluding any combinations of elements in the list of elements. This definition also allows that elements may optionally be present other than the elements specifically identified within the list of elements to which the phrase “at least one” refers, whether related or unrelated to those elements specifically identified. Thus, as a non-limiting example, “at least one of A and B” (or, equivalently, “at least one of A or B,” or, equivalently “at least one of A and/or B”) can refer, in one embodiment, to at least one, optionally including more than one, A, with no B present (and optionally including elements other than B); in another embodiment, to at least one, optionally including more than one, B, with no A present (and optionally including elements other than A); in yet another embodiment, to at least one, optionally including more than one, A, and at least one, optionally including more than one, B (and optionally including other elements); etc. 
     It should also be understood that, unless clearly indicated to the contrary, in any methods claimed herein that include more than one step or act, the order of the steps or acts of the method is not necessarily limited to the order in which the steps or acts of the method are recited. 
     In the claims, as well as in the specification above, all transitional phrases such as “comprising,” “including,” “carrying,” “having,” “containing,” “involving,” “holding,” “composed of,” and the like are to be understood to be open-ended, i.e., to mean including but not limited to. Only the transitional phrases “consisting of” and “consisting essentially of” shall be closed or semi-closed transitional phrases, respectively, as set forth in the United States Patent Office Manual of Patent Examining Procedures, Section 2111.03.