Patent Publication Number: US-2023151750-A1

Title: Electrically heated fluid treatment system for low and high voltage applications

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application claims the benefit of priority under 35 U.S.C. § 119 of U.S. Provisional Application Ser. No. 63/280,213 filed on Nov. 17, 2021, the content of which is relied upon and incorporated herein by reference in its entirety. 
    
    
     FIELD OF THE DISCLOSURE 
     The present disclosure is directed generally to systems and methods for treating fluid streams, more particularly aftertreatment systems for treating engine exhaust, and in particular assemblies for heating a catalyst to improve catalytic performance. 
     BACKGROUND 
     Catalytic converters or other catalyst-loaded aftertreatment components can be used to reduce toxins and pollutants in exhaust gas via chemical reactions between components of the exhaust gas with a catalyst carried by the catalytic converter. Initiation of these chemical reactions, which may be referred to as “light off,” requires sufficiently high temperatures. The heat for light off may be supplied from the heat of the exhaust being treated. As such, catalytic converter performance may be limited in the period immediately following the start of a vehicle&#39;s engine, also known as a “cold start,” during which the temperature of the catalyst is still below its light off temperature. As a result, cold start emissions can be a primary contributor for total tail pipe emission accumulation. 
     There is a need in the art to reduce total emissions, such as by reducing cold start time or otherwise maintaining the catalyst above its light off temperature during engine operation in both low and high voltage applications. 
     SUMMARY 
     This disclosure generally relates to a heater, a method for manufacturing a heater, and a method for heating exhaust gas. 
     Generally, in one aspect, a heater is provided. The heater comprises a honeycomb structure comprising an array of intersecting walls defining channels extending axially between a first face and a second face, wherein the intersecting walls comprise a thermally conductive material; and a resistive heating element engaged against the first face of the honeycomb structure, the heating element comprising an electrically conductive element coated with a thermally-conductive electrical insulator, wherein the thermally-conductive insulator electrically insulates the electrically conductive element from the honeycomb structure. 
     In embodiments, the array of intersecting walls extends to an outer periphery of the honeycomb structure. 
     In embodiments, the walls of the honeycomb structure are made of metal. 
     In embodiments, the resistive heating element is arranged within a trench formed in the first face of the honeycomb structure. 
     In embodiments, the thermally-conductive electrical insulator comprises a ceramic. 
     In embodiments, the electrically conductive element comprises an iron-chromium-aluminum alloy. 
     In embodiments, the resistive heating element is spiral-shaped. 
     In embodiments, the resistive heating element is serpentine or winding-shaped. 
     In embodiments, the electrically conductive element is arranged in parallel with itself in a portion of the resistive heating element. 
     In embodiments, the electrically conductive element and thermally-conductive insulator are at least partially enclosed by an outer jacket. 
     In embodiments, the outer jacket is welded or brazed to the honeycomb structure. 
     In embodiments, the honeycomb structure is less than 1 inch in axial thickness. 
     In embodiments, the heater further comprises a second honeycomb structure, the second honeycomb structure comprising a first face engaged against the resistive heating element. 
     In embodiments, the first face of the second honeycomb structure is engaged against the first face of the honeycomb structure. 
     In embodiments, the resistive heating element is at least partially arranged within a trench formed in the first face of the second honeycomb structure. 
     In embodiments, the resistive heating element is at least partially arranged within a first trench formed in the first face of the first honeycomb structure and at least partially arranged within a second trench formed in the first face of the second honeycomb structure. 
     In embodiments, the honeycomb structure is cylindrical. 
     Generally, in one aspect, an exhaust aftertreatment system is provided. The exhaust aftertreatment system comprising the heater of any of the preceding paragraphs and an aftertreatment component downstream of the heater. 
     In embodiments, the aftertreatment component comprises a catalyst-carrying substrate or a particulate filter. 
     In embodiments, the resistive heating element is connected to a voltage source configured to supply a voltage to the resistive heating element. 
     In embodiments, the voltage is in a range of 12 V to 600 V. 
     In embodiments, the voltage is in a range of 300 V to 600V. 
     In embodiments, the voltage is selected to cause the resistive heating element to generate heat sufficient to increase a temperature of the walls of the honeycomb structure to at least 500 degrees Celsius. 
     In embodiments, the voltage is selected to cause the resistive heating element to generate heat sufficient to increase a temperature of the walls of the honeycomb structure to at least 750 degrees Celsius. 
     Generally, in one aspect, a method for manufacturing a heater is provided. The method comprises forming a honeycomb structure comprising an array of intersecting walls defining channels extending axially between a first face and a second face, wherein the intersecting walls comprise a thermally conductive material; and arranging a resistive heating element against the first face of the honeycomb structure, wherein the resistive heating element comprises an electrically conductive element coated with a thermally-conductive electrical insulator that electrically insulates the electrically conductive element from the honeycomb structure. 
     Generally, in one aspect, a method of treating exhaust gas is provided. The method comprises supplying a resistive heating element engaged against a first face of a honeycomb structure with a voltage, wherein the resistive heating element comprises an electrically conductive element coated with a thermally-conductive electrical insulator that electrically insulates the electrically conductive element from the honeycomb structure, wherein the honeycomb structure comprises an array of intersecting walls defining channels extending axially between the first face and a second face, and wherein the intersecting walls comprise a thermally conductive material; flowing a exhaust gas through the honeycomb structure; and heating a downstream aftertreatment component with the flow of exhaust gas. 
     Other features and advantages will be apparent from the description and the claims. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       In the drawings, like reference characters generally refer to the same parts throughout the different views. Also, the drawings are not necessarily to scale, emphasis instead generally being placed upon illustrating the principles of the various examples. 
         FIG.  1    is a top view of a honeycomb structure, according to an example. 
         FIG.  2 A  is a top view of a spiral-shaped heating element arranged on a honeycomb structure, according to an example. 
         FIG.  2 B  is a cross-sectional view of a spiral-shaped heating element, according to an example. 
         FIG.  3 A  is a top view of a winding-shaped heating element arranged on a honeycomb structure, according to an example. 
         FIG.  3 B  is a cross-sectional view of a winding-shaped heating element, according to an example. 
         FIG.  4    is a perspective view of a spiral-shaped heating element arranged on a honeycomb structure, according to an example. 
         FIG.  5    is a perspective view of a spiral-shaped heating element arranged in between two honeycomb structures, according to an example. 
         FIG.  6    is a schematic of an exhaust system with a heater, according to an example. 
         FIG.  7    is an electrical schematic of an exhaust gas heating system, according to an example. 
         FIG.  8    is a method for manufacturing a heater, according to an example. 
         FIG.  9    is a method of heating exhaust gas, according to an example. 
     
    
    
     DETAILED DESCRIPTION 
     This disclosure generally relates to a heater, a method for manufacturing a heater, and a method for heating exhaust gas, e.g., for use in an automobile or other engine-containing device. These devices, systems, and methods may be useful to improve catalytic converter performance through upstream heating of exhaust gas, thus hastening light off, lowering cold start time, and significantly reducing both cold start emissions and total tail pipe emissions. This upstream heating is achieved using a honeycomb structure with an array of intersecting walls. The intersecting walls form channels extending axially between a first face and a second face of the honeycomb structure, and are made of a thermally conductive material, such as a metal. The array extends to the outer periphery of the honeycomb structure for optimized heating of exhaust gas passing through the channels. 
     The exhaust system of an automobile may be a harsh, wet environment. Accordingly, this environment may present challenges for resistive heaters that have structures (e.g., walls) that directly participate in both the heat generation (due to flowing of current through the structures) as well as heat transfer with the fluid flow, especially at high voltages where the harsh environment may cause electrical shorts or otherwise interfere with electrical performance. As described herein, by decoupling the electrically conductive element (through which current is flowed to generate heat), from the honeycomb structure that performs heat transfer with the exhaust gas, the heaters described herein are applicable to a wide range of voltage applications, including both low and high voltages. 
     The honeycomb structure is heated by a heating element affixed to the first face of the honeycomb structure. The heating element can be arranged within a trench on the first face of the honeycomb structure, and can be configured in a variety of shapes, such as a spiral or a winding. The heating element includes an electrically conductive element coated with a thermally conductive electrical insulator, such as a ceramic. Thus, the heating element heated by the high voltage source is thermally coupled to the honeycomb structure, while also being electrically isolated. 
     This configuration of the honeycomb structure and heating element provides a number of advantages over the existing technology. First, the thermally-conductive honeycomb structure improves heating efficiency with increased surface area compared to similar heaters. Further, due to the electrically insulative structure of the heating element, the configuration is appropriate for a wide range of voltages including both low voltage (e.g., from the batteries of traditional internal combustion engine vehicles) and high voltage (e.g., from the battery systems of hybrid or electric vehicles) applications, such as broadly over a range of about 12 V to about 600 V. Third, engaging the heating element against the honeycomb array provides for a structure with improved durability and stability over similar heaters. 
       FIG.  1    shows an example honeycomb structure  100 . The honeycomb structure  100  is formed by an array  102  of intersecting walls  104 . For example,  FIG.  1    shows how walls  104   a  (extending in a first direction) and walls  104   b  (extending in a second direction) intersect. The intersecting walls  104  form a plurality of channels  106 . The walls  104  are illustrated as defining a square shape for the channels  106 , although other channel shapes can be used, such as hexagonal, rectangular, triangular, or other polygons, or combinations thereof. As shown in  FIG.  1   , the channels can extend to the outer periphery  112  of the honeycomb structure  100 . The walls  104  of the honeycomb structure  100  comprise a thermally conductive material, such as a metal or metal-like material. Accordingly, when the honeycomb structure  100  is heated as described herein, fluid (e.g., exhaust gases) flowing through the channels  106  formed by the intersecting walls  104  is heated by heat transfer with the walls  104  of the honeycomb structure  100 . In one example, the axial thickness of the honeycomb structure is less than two inches, or even less than one inch. However, other axial thicknesses are possible depending on the particulars of the application, such as the dimensions of piping in. The honeycomb structure  100  can be manufactured through a variety of processes, such as extrusion or additive manufacturing. 
       FIG.  2 A  shows a top view of a heater  10  comprising a heating element  200  arranged with the honeycomb structure  100  (the walls  104  of the honeycomb structure  100  not shown in  FIG.  2 A ).  FIG.  2 B  shows a cross-sectional view of the heating element  200 . The heating element  200  is illustrated as having a spiral shape in  FIGS.  2 A- 2 B , although other shapes, such as a serpentine, zig-zag, bent, winding, circuitous, or other shape that fits within the dimensions of the outer perimeter  112  of the honeycomb structure  100 . The heating element  200  engages with, or affixes to, the honeycomb structure  100  in order to transfer heat to the honeycomb structure  100 . The heating element  200  is comprised of an electrically conductive element  202 , such as a wire. When a voltage is applied to the terminals of the electrically conductive element  202 , a current flows through the electrically conductive element  202 . This current causes the electrically conductive element  202  to generate heat due to internal resistance of the electrically conductive element  202 . In one example, the electrically conductive element  202  is an iron-chromium-aluminum alloy, although other electrically conductive materials can be used. This electrically conductive element  202  can have a melting point of at least 1,000 degrees Celsius, or even at least 1,300 degrees Celsius, such as approximately 1,500 degrees Celsius in the case of iron-chromium-aluminum alloys. 
     As shown in  FIG.  2 B , both terminals of the electrically conductive element  202  are accessible at the end of the heating element  200  closest to the outer periphery  112  of the honeycomb structure. This is achieved by running dual parallel segments of the electrically conductive element  202  (such as a pair of wire) throughout the spiral-shaped heating element  200 . The dual parallel segments of the electrically conductive element  202  are electrically coupled at the center-most portion of the spiral-shape to form a single element  202 . In this way, the electrically conductive element  202  is arranged in parallel with itself in at least a portion of the heating element  200 . The electrically conductive element  202  is coated with a thermally-conductive electrical insulator  204 , such as a ceramic. The thermally-conductive electrical insulator  204  can be at least partially encompassed by an outer jacket  206 , such as a metal outer jacket. For example, the outer jacket  206  can be a nickel-chromium alloy. The thermally-conductive electrical insulator  204  separates the electrically conductive element  202  an amount sufficient to provide electrical isolation of the conductive element  202  from the outer jacket  206 , such as by approximately a distance of at least one millimeter, at least two millimeters, or at least three millimeters. 
     In the example of  FIGS.  2 A and  2 B , the outer jacket  206  surrounds almost the entire electrically conductive element  202  with the exception of an opening on the end closest to the outer periphery  112  of the honeycomb structure  100  such that the two terminals of the electrically conductive element  202  can connect to a voltage source (e.g., the battery of an automobile). The outer jacket  206  can be affixed to the honeycomb structure via welding, brazing, mechanical fastening, or another process. This arrangement allows for the resistive heat generated by the electrically conductive element  200  to transfer through the thermally-conductive electrical insulator  204  and the outer jacket  206  to heat the honeycomb structure  100 . At the same time, the thermally-conductive electrical insulator  204  prevents the current flowing through the electrically conductive element  200  from coupling to the outer jacket  206  or the honeycomb structure  100 . In some examples, the parameters of the heater  10 , such as the applied voltage, resistivity/conductivity of the electrical conductor  202 , and heat transfer coefficients between the materials enables a transfer of heat from the outer jacket  206  to the honeycomb structure  100  results in the honeycomb structure  100  heating up to at least 500 degrees Celsius, or even at least 600 degrees Celsius, such as approximately 750 degrees Celsius or more. 
     As shown in  FIG.  2 A , the heater  10  can be cylindrical and can be set by the outer periphery  112  of the honeycomb structure  100 . However, other three-dimensional shapes are possible depending on the particulars of the application, such as a shape of piping an exhaust aftertreatment system  700  illustrated in  FIG.  6    that comprises the heater  10 . 
     The heating element  200  of  FIG.  2 A  has three turns, although additional numbers of turns can be utilized for a spiral-shape design. However, non-spiral designs can be used, such a serpentine designs having a number of bends. In one example, the outer diameter of the shape of the heating element  200  fits within the outer periphery of the honeycomb structure  100 , such as in a range of approximately three to six inches, or larger. Various other combinations of shapes, turns, bends, and/or dimensions of the heating element  200  may be used to achieve efficient heating of the honeycomb structure  100 , e.g., by increasing the contact area available for heat transfer between the heating element  200  and the honeycomb structure  100 . 
       FIGS.  3 A and  3 B  depict a variation of the heater  10  of  FIGS.  2 A and  2 B  wherein the heating element  200  is serpentine or winding-shaped. The winding-shape includes a plurality of parallel sections joined together by curved bends. Further, as shown in the cross-sectional view of  FIG.  3 B , each end of the heating element  200  exposes a terminal of the electrically conductive element  202 . Accordingly, to heat the heating element  200 , both ends of the electrically conductive element  202  must be connected to a voltage source. In further examples, the heating element  200  can be any other shape practical for distributing heat to (e.g., evenly heating) the honeycomb structure  100 . 
       FIG.  4    depicts a perspective view of a heater  10  comprised of the heating element  200  arranged on a first face  108  of the honeycomb structure  100 . The heating element  200  of  FIG.  4    is capable of overlapping itself as shown in  FIG.  4    without short-circuiting due to the thermally-conductive electrical insulator  204 . The heating element  200  is arranged within a trench  114  formed into the first face  108  of the honeycomb structure  100 . The trench  114  can have a depth approximately equal to the thickness of the heating element  200 . For example, the trench  114  can be formed by removing material from the honeycomb structure  100 , such as a milling, cutting, electrical discharge machining, or other process. 
     As previously described, the heating element  200  heats the honeycomb structure  100  when a voltage is applied to the heating element  200 . Thus, the heater  10  can operate by heating a fluid flow  400  (e.g., a flow of exhaust gases or other fluid to be treated) passing through the channels  106  of the honeycomb structure  100 . In one example, the fluid flow  400  can be exhaust gas generated by the engine of an automobile. The heated exhaust gas is then provided to a downstream exhaust aftertreatment component such as a catalytic converter or particulate filter, resulting in improved emission performance. 
       FIG.  5    depicts a perspective view of heater  100  comprised of the heating element  200  arranged in between the honeycomb structure  100  as a first honeycomb structure and a second honeycomb structure  300 . The second honeycomb structure  300  can be arranged as shown in the drawings and described herein with respect to the first honeycomb structure  100 , e.g., comprising the array of intersecting walls  104  that define channels  106  therethrough. In the example of  FIG.  5   , a first face  302  of the second honeycomb structure  300  is affixed to the first face  108  of the first honeycomb structure  100 . The first and second honeycomb structures  100 ,  300  can be thermally coupled at an interface  304 . For example, the interface  304  can comprise a thermal paste, an adhesive, brazing, welding, or other material if desired. Alternatively, the first honeycomb structure  100  and second honeycomb structure  300  can be held together by clips, bolts, clamps, or other mechanical fasteners. In embodiments, each of the honeycomb structure  100 ,  300  are less than 1 inch in axial thickness, or even less than 0.5 inches in axial thickness, such as approximately 0.25 inches in axial thickness or between 0.1 inches and 0.5 inches. 
     In order to arrange the heating element  200  between the first and second honeycomb structures  100 ,  300  a first trench  114  can be milled into the first face  108  of the first honeycomb structure  100 , and/or a second trench  306  can be milled in the first face  302  of the second honeycomb structure  300 . As such, the heating element  200  shown in  FIG.  5    is arranged within the one or more trenches  114 ,  306 . For example, the sum of the depths of the trenches  114 ,  306  can be substantially equal to the thickness of the heating element  200 . In this way, even if one of the trenches is not included (thus, effectively has a depth of zero), the depth of the single trench would be substantially equal to the thickness of the heating element  200 . In embodiments, the depth of the first trench  114  and the depth of the second trench  306  are both substantially equal to half of the thickness of the heating element  200 . In an alternate example, the depth of the first trench  114  is approximately 75% of the thickness of the heating element  200 , while the depth of the second trench  306  is approximately 25% of the thickness of the heating element  200 . Other ratios of trench depths are possible. The dual honeycomb structure  100 ,  300  arrangement of  FIG.  5    can produce improved heating of fluid flow  400  by utilizing conduction heat from opposite (e.g., both the top and bottom) sides of the heating element  200 . Similar to the interface  304 , heat transfer between the heating element  200  and the honeycomb structure  100  can be increased by addition of a thermal paste, adhesive, welding, brazing, or even mechanical fasteners that improve the thermal communication between the materials of these components. 
     In other examples, neither the honeycomb structures  100 ,  300  include a trench  114 ,  306  in which the heating element  200  is received. In this embodiment, the first face  108  of the first honeycomb structure  100  is only connected to the first face  302  of the second honeycomb structure  300  via the heating element  200  (and thus there is no interface  304  between the honeycomb structures  100 ,  300 ). This arrangement results in a physical gap between the first honeycomb structure  100  and the second honeycomb structure  300 , which may lead to mixing of the heated fluid flow  400  with additional external, non-heated air or other gases that is pulled into the gap. 
       FIG.  6    is a schematic of an exhaust aftertreatment system  700  with the heater  10  (comprising only the honeycomb structure  100  but not the honeycomb structure  300 , although the heater  10  can comprise both of the honeycomb structures  100 ,  300 ). The fluid flow  400 , such as exhaust gas generated by the engine of the automobile, flows through the honeycomb structure  100 , which is heated by the heating element  200  as described herein. After the fluid flow  400  is heated by the heater  10 , the heated fluid flow can be directed to an exhaust aftertreatment component  20 , such as a catalytic converter (or other catalyst-carrying substrate) or particulate filter. The heating element  200  connects to the automobile electrical system  800  via one or more electrodes  402 . The heater  10  can be secured in place via retention ring  404 , matting material  406 , and/or other suitable components. For example, matting material  406  can be included to act as a cushion between the retention ring  404  and the heater  10  in the axial direction. Additional matting material  408  can be used about the outer periphery of the honeycomb structure  100  to prevent movement of the heater  10 , e.g., due to vibrations during use. The fluid flow  400  exiting the heater  10  then travels to a downstream aftertreatment component, e.g., a catalytic converter or particulate filter, of the automobile. 
       FIG.  7    is an electrical schematic of the exhaust aftertreatment system  700 , according to an example. As shown in  FIG.  7   , the automobile electrical system  800  provides heating element  200  with a voltage, V DC . The heating element  200  uses the V DC  to generate resistive heat, which is transferred to the thermally-conductive honeycomb structure  100 . V DC  can be a relatively high voltage value, such as between 300 V and 600 V. This high voltage value can be due to the automotive electrical system  800  providing electrical power to an electrically powered vehicle or an automobile with a hybrid powertrain. In other examples, V DC  can be a relatively low voltage value, such as between 12 V and 48 V. In a further example, V DC  can be any voltage value between 12 V and 600 V. Accordingly, the heater  10  is a flexible device capable of being used in both low voltage and high voltage applications. 
     Generally, in another aspect and with reference to  FIG.  8   , a method  500  for manufacturing a heater is provided. The method  500  comprises forming  502  a honeycomb structure comprising an array of intersecting walls forming channels extending axially between a first face and a second face, wherein the intersecting walls comprise a thermally conductive material. In embodiments, the forming  502  is performed by extrusion or additive manufacturing. 
     The method  500  optionally further comprises forming  504  a trench on the first face of the honeycomb structure. In embodiments, the trench is formed in step  504  simultaneously with the honeycomb structure, e.g., via an additive manufacturing process. In embodiments, the trench is formed in step  504  by removing material from the honeycomb structure formed in step  502 . In embodiments, the method  500  does not comprise forming a trench. The resistive heating element may comprise an electrically conductive element coated with a thermally-conductive electrical insulator. The electrically conductive element and thermally-conductive electrical insulator may be at least partially enclosed or encased in an outer jacket. The method  500  further comprises arranging  506  a resistive heating element against the first face of the honeycomb structure. In embodiments, arranging  506  comprises positioning the heating element within the trench if the method  500  comprises the step  504 . The method  500  optionally further comprises securing  508  the heating element to the honeycomb structure. In embodiments, the securing  508  comprises welding, adhering, brazing, or mechanically connecting the heating element to the first face of the honeycomb structure. 
     Generally, in another aspect, and with reference to  FIG.  9   , a method  600  of heating exhaust gas is disclosed. The method  600  comprises supplying  602  a resistive heating element engaged against a first face of a honeycomb structure with a voltage. The, In embodiments, the resistive heating element comprises an electrically conductive element coated with a thermally-conductive electrical insulator. In embodiments, the electrically conductive element and the thermally-conductive insulator are at least partially encompassed within an outer jacket. In embodiments, the honeycomb structure comprises an array of intersecting walls defining channels extending axially between the first face and a second face. In embodiments, the intersecting walls comprise a thermally conductive material. 
     The method  600  further comprises flow  604  a fluid, e.g., exhaust gas, through the honeycomb structure, thereby heating the exhaust gas by heat transfer with the walls of the honeycomb structure. The method  600  further comprises heating  606 a downstream exhaust aftertreatment component with the flow of exhaust gas after the exhaust gas has been heated, thereby providing the downstream exhaust aftertreatment component, such as a catalyst-carrying substrate or particulate filter, with supplemental heat. In embodiments, the supplemental heat provided by the heater to the exhaust flow, and by the exhaust flow to the aftertreatment component is sufficient to initiate light off of a catalyst material carried by the aftertreatment component. 
     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 can optionally be present other than the elements specifically identified by the “and/or” clause, whether related or unrelated to those elements specifically identified. 
     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.” 
     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 can 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. 
     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. 
     The above-described examples of the described subject matter can be implemented in any of numerous ways. For example, some aspects can be implemented using hardware, software or a combination thereof. When any aspect is implemented at least in part in software, the software code can be executed on any suitable processor or collection of processors, whether provided in a single device or computer or distributed among multiple devices/computers. 
     The flowchart and block diagrams in the Figures illustrate the architecture, functionality, and operation of possible implementations of systems, methods, and computer program products according to various examples of the present disclosure. In this regard, each block in the flowchart or block diagrams can represent a module, segment, or portion of instructions, which comprises one or more executable instructions for implementing the specified logical function(s). In some alternative implementations, the functions noted in the blocks can occur out of the order noted in the Figures. For example, two blocks shown in succession can, in fact, be executed substantially concurrently, or the blocks can sometimes be executed in the reverse order, depending upon the functionality involved. It will also be noted that each block of the block diagrams and/or flowchart illustration, and combinations of blocks in the block diagrams and/or flowchart illustration, can be implemented by special purpose hardware-based systems that perform the specified functions or acts or carry out combinations of special purpose hardware and computer instructions. 
     Other implementations are within the scope of the following claims and other claims to which the applicant can be entitled. 
     While various examples 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 examples 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 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 examples described herein. It is, therefore, to be understood that the foregoing examples are presented by way of example only and that, within the scope of the appended claims and equivalents thereto, examples can be practiced otherwise than as specifically described and claimed. Examples 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 scope of the present disclosure.