Patent Publication Number: US-2020290279-A1

Title: Three-dimensional printer, feed system and method

Description:
BACKGROUND 
     Additive production techniques involve depositing successive layers of a material in a pattern to form a product. The material being deposited is typically converted into a flowing form from a solid material. However, conventional additive production systems have traditionally employed separate, complex systems to individually transport the solid material and meter the material being deposited. 
     SUMMARY 
     In accordance with the present disclosure, a feed system for a printer that builds a three-dimensional product is provided. The feed system includes a feed chamber that stores a particulate material, and a deposition chamber that receives the particulate material stored by the feed chamber. A heater is in thermal communication with the deposition chamber to elevate a temperature of the particulate material within a heating region of the deposition chamber, thereby converting the particulate material into a gel. A nozzle is provided to the deposition chamber to emit the gel in a pattern to build the three-dimensional product. A conveyance system transports the particulate material towards the heating region and expels the gel from the deposition chamber through the nozzle. A control system in communication with the conveyance system controls operation of the conveyance system. 
     According to some examples, a printer that builds a three-dimensional product includes a platen that supports the three-dimensional product while the three-dimensional product is being built. A control system controls movement of the platen and a plurality of feed systems during building of the three-dimensional product. Each, or at least one of the feed systems includes a feed chamber that stores a particulate material, and a deposition chamber that receives the particulate material stored by the feed chamber. A heater is in thermal communication with the deposition chamber to elevate a temperature of the particulate material within a heating region of the deposition chamber to convert the particulate material into a gel. A nozzle provided to the deposition chamber emits the gel in a pattern to build the three-dimensional product. A conveyance system transports the particulate material towards the heating region and expels the gel from the deposition chamber through the nozzle. 
     Some examples involve a method of operating a feed system of a printer that builds a three-dimensional product. The method involves using a control system comprising a processor that executes computer-executable instructions stored by a non-transitory computer-readable memory. Operation of a heater in thermal communication with a heating region of the deposition chamber is initiated to convert a particulate material in the heating region into a gel. A control signal is issued to selectively operate a conveyance system to urge the particulate material into a deposition chamber, and expel the gel from a nozzle provided to the deposition chamber. A platen supporting the three-dimensional product being built is moved to cause the gel to be deposited in a pattern corresponding to the three-dimensional product. An ultraviolet light source is energized to irradiate the gel being expelled from the nozzle with ultraviolet light. 
    
    
     
       DESCRIPTION OF THE DRAWINGS 
       While the techniques presented herein may be embodied in alternative forms, the particular embodiments illustrated in the drawings are only a few examples that are supplemental of the description provided herein. These embodiments are not to be interpreted in a limiting manner, such as limiting the claims appended hereto. 
         FIG. 1  is a block diagram schematically illustrating a three-dimensional printer including an illustrative example of a feed system. 
         FIG. 2  is a block diagram schematically illustrating a three-dimensional printer including a plurality of feed systems. 
         FIG. 3  is a block diagram schematically illustrating a portion of one feed system shown in  FIG. 2 , including a conveyance system that utilizes a gas to transport particulate material and expel a gel from a deposition chamber, where a supply door is in an open state and a charge door is in a closed state. 
         FIG. 4  is a block diagram schematically illustrating the portion of the feed system shown in  FIG. 3 , with the supply door in a closed state and the charge door in an open state. 
         FIG. 5  is a flow diagram schematically illustrating a method of operating a feed system of a printer with a control system to build a three-dimensional product. 
         FIG. 6  shows an illustrative embodiment of an ultraviolet light emitting diode (UV LED) that can be used to cure deposited gel material using ultraviolet light. 
     
    
    
     DETAILED DESCRIPTION 
     Subject matter will now be described more fully hereinafter with reference to the accompanying drawings, which form a part hereof, and which show, by way of illustration, specific example embodiments. This description is not intended as an extensive or detailed discussion of known concepts. Details that are known generally to those of ordinary skill in the relevant art may have been omitted, or may be handled in summary fashion. 
     The following subject matter may be embodied in a variety of different forms, such as methods, devices, components, and/or systems. Accordingly, this subject matter is not intended to be construed as limited to any illustrative embodiments set forth herein as examples. Rather, the embodiments are provided herein merely to be illustrative. Such embodiments may, for example, take the form of hardware, software, firmware or any combination thereof. 
     One or more feed systems for a printer that builds a three-dimensional product, one or more printers with at least one such feed system, and a method of operating one or more such feed systems are provided. For example, each, or at least one feed system includes a conveyance system. The conveyance system is operable to transport a particulate material toward a heating region of a deposition chamber to be converted into a gel, and expel the gel from the deposition chamber through a nozzle. The conveyance system can be also controlled independently of at least one other feed system provided to the same printer. Some embodiments of the conveyance system utilize a gas from a common gas source to transport the particulate material toward the heating region and to expel the gel from the deposition chamber for each of a plurality of independently-operated feed systems. 
     With reference to the drawings,  FIG. 1  schematically shows an example of a three-dimensional printer  100  including an example of a feed system  105 . As shown, the feed system  105  includes a feed chamber  110  that stores a particulate material  115 , such as particles of a thermosetting resin, a thermoplastic resin, or other material. The feed chamber  110  can define an enclosed compartment in which a quantity of the particulate material  115  can be staged for delivery to a deposition chamber  120 . A conduit  125  extending between the feed chamber  110  and the deposition chamber  120  establishes a feed path along which the particulate material  115  is supplied to the deposition chamber  120 . A valve  130  can be electronically actuated, pneumatically-actuated, or actuated by other means according to a control routine executed by a control system  135  to supply the required particulate material  115  to the deposition chamber. Examples of the valve  130  include, but are not limited to a gate valve, a ball valve, etc. 
     The deposition chamber  120  can include a substantially-cylindrical vessel formed from stainless steel or other rigid material. The material from which the deposition chamber  120  is formed can withstand high temperatures in excess of one hundred (100° C.) degrees Celsius, or other temperatures required to melt the particulate material  115  into a gel  140 , for example, without the deposition chamber  120  being plastically deformed. A nozzle  145  defines an orifice through which the gel  140  is expelled from the deposition chamber as a stream with a cross-sectional shape suitable to build the three-dimensional product as part of the additive production process. 
     An electric heater  150  is provided adjacent to, and optionally at least partially (or fully) surrounds an exterior of the deposition chamber  120  to create a heating region  155 . The heater  150  is in sufficient thermal communication with the heating region of the deposition chamber  120  to melt the particulate material  115  within the heating region  155 . Melting the particulate material  115  creates a viscous volume, referred to herein as the gel  140 , of the material introduced to the deposition chamber  120  in particulate form. The gel  140  can be expelled in a continuous stream under pressure exerted on the particulate material  115  within the deposition chamber  120  by a conveyance system  160 , as described below. 
     The illustrative example of the conveyance system  160  shown in  FIG. 1  includes a stepper motor  165  or other driver operatively connected to the control system  135  by a hardwired or wireless communication channel  170 . The control system  135  can optionally include a processor  152  that executes computer-executable instructions stored in a non-transitory memory  154 , for example. Although a control system is represented by a single block in  FIG. 1 , utilizing a processor  152  and a memory  154 , the control system  135  can be a distributed system, including a plurality of control modules, controlling different components of the printer  100 . Under the control of the control system  135 , the stepper motor  165  is operated to drive a linkage comprising one or a plurality of rotatable lead screws  175  in response to a demand for the gel  140  to be deposited as part of the additive production process. Rotation of the lead screws  175  causes insertion of a plunger  180  into the deposition chamber  120  in the direction of nozzle  145 . The resulting pressure exerted on the particulate matter  115  and gel  140  within the deposition chamber  120  expels the gel  140  through the nozzle  145  onto a platen  185  supporting the product being built during the additive production process. 
     Gel  140  expelled from the deposition chamber  120  is deposited onto the platen  185 , or onto previously-deposited gel  140  forming an underlying layer of the product being built. Deposited gel can be allowed to cool and solidify to form a layer of the product, or the deposited gel can be cured to form a layer of the product. Curing the gel can involve molecular crosslinking an ultraviolet light curable resin through exposure to ultraviolet light emitted by an array of ultraviolet light emitting diodes (“LEDs” or “UV LEDs”)  190 , or exposure to heat or another crosslinking agent. The UV LEDs  190 , described below with reference to  FIG. 6 , can be arranged at a stationary location adjacent to the nozzle  145  or on an articulating (e.g., robotic) arm to immediately irradiate the gel  140  as the gel  140  is deposited in a gelled state, in which the gel  140  is mobile, or flowable in a manner similar to a viscous fluid. The position of the platen  185  is adjusted by an actuator  195  according to instructions from the control system  135  as the gel  140  is deposited to establish the shape of the product being produced. 
     Some embodiments of a conveyance system  260  ( FIGS. 3 and 4 ) can utilize fluid pressure or fluid flow to transport the particulate material from the feed chamber to the deposition chamber. For example,  FIG. 2  illustrates an embodiment of a printer  200  that includes a plurality of feed systems  202 . Each, or a plurality or at least one of the feed systems  202  includes such a conveyance system  260 . One or more, and optionally each of the feed systems  202  includes a feed chamber  210  that stores the particulate material  115  to be supplied to a deposition chamber  220 . The stored particulate material  115  can be conveyed through a conduit extending between the feed chamber  210  and the deposition chamber  220 . The particulate material  115  delivered to the deposition chamber  220  is melted within the heating zone  255  to form the gel  140 . The delivery of the particulate material  115  to the deposition chamber  220  expels the gel  140  from the deposition chamber  220  through the nozzle  245  onto the platen  285 , which is moved by the actuator  295 . The deposited gel  140  can then be cured in response to being exposed to ultraviolet light emitted by an array of UV LEDs  290 . Such features are similar to the respective features described with reference to  FIG. 1 , so further discussion of those features is omitted here. 
     The feed systems  202  in  FIG. 2  can be independently controlled by the control system  235  to deposit one, or a plurality of different materials, as required to produce the desired product. Controlling the supply of the particulate material  115  for the feed systems  202  can be achieved by a conveyance system  260  that controls the flow of a gas from a gas source  212  using a network of valves. For the sake of clearly illustrating embodiments of the feed system  202 , a portion of one feed system  202  provided to the printer  200  in  FIG. 2  is shown in  FIGS. 3 and 4 , isolated from the other feed systems  202  provided to the printer  200 . However, the structure and operation of the portion of the feed system  202  described below with reference to  FIGS. 3 and 4  can be the same for each of the feed systems  202  shown in  FIG. 2 . According to embodiments utilizing a mobile nozzle  145 , the UV LEDs  190  can be coupled in a fixed relationship relative to the nozzle  145  to move along with movement of the nozzle  145 . 
     An illustrative embodiment of the UV LEDs  190  that can be used to cure deposited gel material using ultraviolet light is shown in  FIG. 6 . An ultraviolet light source such as a high-power UV LED bulb  600  can be mounted to a circuit board  605  supporting circuitry for controlling operation of the UV LED bulb  600 . High-power UV LED bulbs  600  can draw currents of at least one (1 A) amp, at least two (2 A) amps, at least three (3 A) amps, etc. To protect such a high-power UV LED bulb  600  from degradation as a result of overheating, the circuit board  605  can include a metal or metal-alloy layer  620  (shown using hidden lines) forming a portion of the circuit board&#39;s core or substrate. The metal or metal-alloy material (e.g., aluminum, copper, combinations and alloys thereof, etc.) can be placed in thermal communication with a heat sink  610 . Thermal paste or other heat-conducting joining material can be disposed between the circuit board  605  and the heat sink  610  to facilitate the transfer of thermal energy away from the UV LED bulb  600 . A fan  615  or other cooling device such as a liquid reservoir, phase change refrigeration device, etc. can be coupled to remove thermal energy from the heat sink at a rate that exceeds the rate of cooling afforded by natural convection. Operation of the UV LEDs  190  can be controlled by the control system as described herein. 
     Ultraviolet light emitted by the UV LED bulb(s)  600  may be omnidirectional according to some embodiments. A lens  625  can be arranged adjacent to the UV LED bulb(s)  600  to focus the omnidirectional ultraviolet light in a direction toward a target location. The target location can be a point where the gel  140  is expelled from the nozzle  145  onto an underlying surface, such as previously-extruded gel  140  forming a portion of the three-dimensional product or the platen  285  for example. Embodiments of the lens  625  can be formed from any ultraviolet-transparent material such as quartz, for example. 
     With reference to  FIGS. 2 and 3 , the gas source  212  can be a cylinder or other suitable reservoir storing a gas at an elevated pressure, relative to atmospheric pressure, such as compressed air, an inert gas such as nitrogen, or other transport gas. The gas can optionally be chosen such that the gas does not undergo a chemical reaction with the particulate material  115 . The gas source  212  can optionally be integrally installed as part of the printer  200 , or can be an external source, that does not form part of the printer  200  but is coupled to an inlet port of the printer  200 . 
     The gas from the gas source  212  flows through a regulator  214  to establish an inlet pressure suitable for the conveyance system  260 . The gas is turned on or off to the system by a valve  216 , which can be electronically controlled by the control system  235 , but can be a pneumatically-actuated valve or actuated by any other suitable mechanism according to some embodiments. When the system is operational this valve  216  can remain in the open state, allowing the gas from the regulator  214  to reach a valve  218  that is operable to isolate the gas flow of one conveyance system  260  from at least one, and optionally each of the other conveyance systems  260  provided to the printer  200 . For the feed system  202  to become operational, the valve  218  is opened to allow the gas from the gas source  212  to enter an inlet port provided to a gas tank  222  specific to the feed system  202 , thereby filling the gas tank  222 . The gas supplied from the gas tank  222  is used to transport the particulate material  115  through the feed system  202 . 
     The valve  218  can open and close in a minimal amount of time designated t valve . Opening and closing the valve  218  at the minimum time t valve  will cause an increase in pressure on the system side of the valve  218  (i.e., the side downstream of the valve  218  where the gas tank  222  is located), as shown in  FIG. 3 . The pressure on the supply side of the valve  218  (i.e., the side upstream of the valve  218  where the gas source  212  is located) is controlled by the pressure regulator  214 . The change in pressure within the feed system  202  with the valve  218  opening and closing in time t valve  is represented by expression [1], which is defined as follows: 
     
       
         
           
             
               
                 
                   
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     where R is the ideal gas constant (8.314 J/mol. K), T is the temperature of the gas, {dot over (m)} is the mass flow rate of the gas and V is the volume of the portion of the feed system  202  on the system side of the valve  218 . The volume of the gas tank  222  can be chosen to establish a desired resolution of the pressure change on the system side of the valve  218  in the feed system  202 . 
     For Mach numbers satisfying the inequality 
     
       
         
           
             
               
                 
                   
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     the mass flow is given by expression [2], which is defined as follows: 
     
       
         
           
             
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     In expression [2], A is the cross sectional area of the tubing/pipe carrying the gas, f is the friction factor of the tubing/pipe, L is the length of the tubing/pipe, D is the diameter of the tubing/pipe, k is the ratio of the specific heats. Equation [1] shows that the pressure change is inversely proportional the volume of the feed system  202 , which can be established by selecting a suitably-sized gas tank  222  for each feed system  202 . The change in pressure in the deposition chamber  220  is a function of the pressure change in equation [1], which translates into the change in force applied to the particulate material  115  in the deposition chamber  220  and, accordingly, the force imparted on the gel  140  in the deposition chamber  220 . Thus, the amount of gel  140  expelled from the nozzle  245  of the deposition chamber  220  is proportional to the pressure change on the gel  140 . 
     The volume of the gas tank  222  is a factor that at least partially, and optionally primarily defines the quantity of the gel  140  that can expelled from the deposition chamber  220  with a single opening of the valve  218 , while a valve  224  between the gas tank  222  and the feed chamber  210  remains open. The gel  140  can optionally be expelled from the deposition chamber  220  at a substantially constant rate by maintaining the valves  218 ,  224  in an open state (e.g., a state that allows the gas to flow through the valves  218 ,  224 ). In other words, the deposition path (denoted by the letter “D” at the outlet of the gas tank  222 ) stemming from the gas tank  222  is opened to convey the gas for depositing the gel  140  without introducing new particulate material  115  to the feed chamber  210 . The gas flowing through the valves  218 ,  224  and the conduit  226  result in the opening of a supply door  228  leading into the feed chamber  210  as shown in  FIG. 3 . The supply door  228  is normally biased closed by a torsion spring  232  or other suitable biasing device. With the supply door  228  pushed open by the pressure of the gas, the pressure within the feed chamber  210  grows as a result of the influx of the gas. The elevated pressure within the feed chamber  210  urges the particulate material  115  from the feed chamber  210  into the deposition chamber  220 . Further, the elevated pressure within the feed chamber also causes the gel  140  to be expelled from the deposition chamber  220  onto the movable platen  285 . 
     A relief valve  234  between the valve  224  and the feed chamber  210  allows for the pressure within the conduit  226  be at least partially relieved by venting at least a portion of the gas in the conduit  226  to the ambient environment. Venting the portion of the gas from the conduit  226  lowers the pressure in the conduit  226  to a level that can be overcome by the force of the torsion spring  232 , causing the supply door  228  to return to a closed state. Venting the portion of the gas via the relief valve  234  also terminates deposition of the gel  140  from the deposition chamber  220 . 
     The conveyance system  260  also includes a replenishment path (denoted by the letter “R” at the outlet of the gas tank  222 ) stemming from the gas tank  222 . The replenishment path ultimately leads to the feed chamber  210 , but includes a hopper  236  that stores a quantity of the particulate matter  115  to be delivered to the feed chamber  210  for replenishing the particulate material supply within the feed chamber  210 . Along the replenishment path, a relief valve  238  is arranged between a valve  240  and the gas tank  222 . The relief valve  238 , when opened by the control system  235 , vents the gas from the gas tank  222  and the portion of the replenishment path between the valve and the gas tank  222  to the ambient environment of the conveyance system  260 . Similarly, a relief valve  242  can be provided along the replenishment path between the hopper  236  and the valve  240 . 
     As shown in  FIG. 4 , the valve  240  can be electronically-actuated, pneumatically actuated, or actuated in any other manner to open the conduit of the replenishment path between the hopper  236  and the gas tank  222 . Adjusting the valve  240  to open the conduit of the replenishment path results in the gas flowing from the gas tank  222  to the hopper  236 . The gas flow through the hopper  236  entrains the particulate material  115  in the flowing gas, or otherwise urges the particulate material  115  in the hopper  236  into the feed chamber  210 . As shown in  FIG. 4 , the pressure resulting from the gas passing through the hopper opens a charge door  244  along the replenishment path that is normally biased closed by a torsion spring  246  or other biasing mechanism. Particulate material  115  entrained within the gas or expelled from the hopper  236  by the pressure increase caused by the influx of gas into the hopper  236  enters the feed chamber  210  through the open charge door  244 . The elevated pressure within the feed chamber  210  from the influx of gas passing through the hopper  236  also urges the supply door  228  closed, preventing the backflow of particulate material  115  up the deposition path. This elevated pressure is also imparted on the particulate material  115  and gel  140  within the deposition chamber  220 , causing the gel  140  to be expelled from the nozzle  245 . When the quantity of the particulate material  115  within the feed chamber  210  has reached a threshold level, the valve  240  can be closed, and the pressure within the hopper at least partially relieved through operation of the relief valve  242 . Operation of the relief valve  242  can also optionally relieve sufficient pressure along the replenishment path to allow the force of the torsion spring  246  to close the charge door  244 . 
     Continued deposition of the gel  140  without transporting the particulate material  115  from the hopper  236  to the feed chamber  210  can be achieved by opening the deposition path through operation of the valve  224 . The supply door  228  will be opened, and the charge door  244  will be maintained in a closed state. Regardless of whether the particulate material  115  is being transported to the feed chamber  210 , as the gel  140  is being deposited, it is illuminated by high intensity ultraviolet light emitted by the UV LEDs  290 , curing the gel as it is being deposited. 
     The control system described herein, and as shown in the drawings, can optionally include a processor, such as processor  252  in  FIG. 2  for example, that executes computer-executable instructions stored by a non-transitory computer-readable memory, such as memory  254  in  FIG. 2  for example, to perform the control operations described herein. The processor  252  and memory  254  can optionally be packaged as a monolithic semiconducting circuit component, with the executable instructions stored as firmware. Although the control system is shown in the drawings as a single block, it is to be understood that the control system  135 ,  235 , can be a distributed system, including a plurality of distributed components, and is not limited to a single controller. Regardless of the structure of the control system, the executable instructions can transmit signals along wired or wireless communication channels (such as the channels  170  shown in  FIG. 1 , for example) to control: actuation of any of the valves described herein, operation of a heater in thermal communication with a heating region of the deposition chamber, operation of the UV LEDs, movement of the platen, or operation of the stepper motor. 
     A flow diagram schematically illustrating a method of operating the feed system  202  of the printer  200  with the control system  235  to build a three-dimensional product is shown in  FIG. 5 . Operation of the heater  250  in thermal communication with the heating region  255  of the deposition chamber  220  is initiated at  500 . The thermal energy emitted by the heater  250  converts a particulate material  115  into a gel  140  to be deposited onto the platen  285  during the additive production process. Operation of the conveyance system  260  is initiated at  505  to transport the particulate material  115  to the feed chamber  210  and then into the deposition chamber  220 , where the particulate material  115  is converted into the gel  140 . The mode of operation of the conveyance system  260  depends on whether there is at least a threshold quantity of the particulate material  115  in the feed chamber  210 . 
     If, at  510 , it is determined that at least the threshold quantity of the particulate material  115  is present in the feed chamber  210 , the valve  224  is operated to open the deposition path at  515 . The replenishment path remains closed. With the deposition path open, gas flows into the feed chamber  210  through the open supply door  228  and elevates the pressure therein. The elevated pressure urges the particulate material  115  from the feed chamber  210  into the deposition chamber  220  and into the heating region  255 , where the particulate material  115  is melted to form the gel  240 . The elevated pressure also causes the gel  140  to be expelled from the deposition chamber  220  via the nozzle  245 . 
     If, at  510 , it is determined that the threshold quantity of the particulate material  115  is not present in the feed chamber  210 , the valve  240  is operated to open the replenishment path at  520 . The deposition path remains closed. With the replenishment path open, gas flows into the hopper  236 , conveying the particulate material  115  from the hopper  236  into the feed chamber  210  through the open charge door  244 , and elevates the pressure within the feed chamber  210 . The elevated pressure urges the particulate material  115  from the feed chamber  210  into the deposition chamber  220  and into the heating region  255 , where the particulate material  115  is melted to form the gel  240 . The elevated pressure also causes the gel  140  to be expelled from the deposition chamber  220  via the nozzle  245 . 
     Throughout deposition of the gel  140 , movement of the platen  285  relative to the nozzle  245  of the deposition chamber  220  is controlled at  525  to create the pattern of the deposited gel  140  corresponding to the product. Ultraviolet light is emitted at  530  to cure the gel  140  as it is deposited, resulting in the accumulation of the gel  140  during the additive production process. The process returns to  510  to monitor the quantity of the particulate material  115  in the feed chamber  210  during the additive production process at  510 . 
     As used in this application, “module,” “system”, “interface”, and/or the like are generally intended to refer to a computer-related entity, either hardware, a combination of hardware and software, software, or software in execution. For example, a component may be, but is not limited to being, a process running on a processor, a processor, an object, an executable, a thread of execution, a program, and/or a computer. By way of illustration, both an application running on a control system and the control system can be a component. One or more components may reside within a process and/or thread of execution and a component may be localized on one computer and/or distributed between two or more computers (e.g., nodes(s)). 
     Unless specified otherwise, “first,” “second,” and/or the like are not intended to imply a temporal aspect, a spatial aspect, an ordering, etc. Rather, such terms are merely used as identifiers, names, etc. for features, elements, items, etc. For example, a first object and a second object generally correspond to object A and object B or two different or two identical objects or the same object. 
     Moreover, “example,” “illustrative embodiment,” are used herein to mean serving as an instance, illustration, etc., and not necessarily as advantageous. As used herein, “or” is intended to mean an inclusive “or” rather than an exclusive “or”. In addition, “a” and “an” as used in this application are generally be construed to mean “one or more” unless specified otherwise or clear from context to be directed to a singular form. Also, at least one of A and B and/or the like generally means A or B or both A and B. Furthermore, to the extent that “includes”, “having”, “has”, “with”, and/or variants thereof are used in either the detailed description or the claims, such terms are intended to be inclusive in a manner similar to the term “comprising”. 
     Although the subject matter has been described in language specific to structural features and/or methodological acts, it is to be understood that the subject matter defined in the appended claims is not necessarily limited to the specific features or acts described above. Rather, the specific features and acts described above are disclosed as example forms of implementing at least some of the claims. 
     Furthermore, the claimed subject matter may be implemented as a method, apparatus, or article of manufacture using standard programming and/or engineering techniques to produce software, firmware, hardware, or any combination thereof to control a computer (e.g., node) to implement the disclosed subject matter. The term “article of manufacture” as used herein is intended to encompass a computer program accessible from any computer-readable device, carrier, or media. Of course, many modifications may be made to this configuration without departing from the scope or spirit of the claimed subject matter. 
     Various operations of embodiments and/or examples are provided herein. The order in which some or all of the operations are described herein should not be construed as to imply that these operations are necessarily order dependent. Alternative ordering will be appreciated by one skilled in the art having the benefit of this description. Further, it will be understood that not all operations are necessarily present in each embodiment and/or example provided herein. Also, it will be understood that not all operations are necessary in some embodiments and/or examples. 
     Also, although the disclosure has been shown and described with respect to one or more implementations, equivalent alterations and modifications will occur to others skilled in the art based upon a reading and understanding of this specification and the annexed drawings. The disclosure includes all such modifications and alterations and is limited only by the scope of the following claims. In particular regard to the various functions performed by the above described components (e.g., elements, resources, etc.), the terms used to describe such components are intended to correspond, unless otherwise indicated, to any component which performs the specified function of the described component (e.g., that is functionally equivalent), even though not structurally equivalent to the disclosed structure. In addition, while a particular feature of the disclosure may have been disclosed with respect to only one of several implementations, such feature may be combined with one or more other features of the other implementations as may be desired and advantageous for any given or particular application.