OPTIMIZED FRAGMENT GEOMETRY FOR AN EXPLOSIVE PROJECTIVE DEVICE AND ASSOCIATED DESIGN AND MANUFACTURING METHODS

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001]This application claims priority to and the benefit of U.S. Provisional Patent Application No. 63/384,876, titled “OPTIMIZED FRAGMENT GEOMETRY FOR AN EXPLOSIVE PROJECTIVE DEVICE AND ASSOCIATED DESIGN AND MANUFACTURING METHODS,” filed on Nov. 23, 2022, the contents of which are incorporated herein by reference in their entireties.

BACKGROUND

[0002]Fragmentation warheads include an explosive material or compound enveloped by a casing, usually made of a metallic, ceramic, or other material. When the explosive is detonated, the rapid expansion, pressure, and heat breaks the casing into fragments that are propelled away in various directions, creating projectiles that eliminate targets.

SUMMARY

[0003]Disclosed are optimized fragment geometry designs for an explosive projectile device, such as a warhead, for improved and/or mission-specific performance, such increased flight distance of fragments driven by explosive gas expansion, increased penetration, and/or the like. In some embodiments, the optimized projectile device includes an explosive interior core, a metallic casing composed of optimized fragment structures, and a polymer-based buffer layer (of minimal thickness) between the casing and the core.

[0004]In some implementations, a mechanism by which disclosed technology enables improved explosive projectile device (e.g., warhead) performance is via an optimized fragment geometry design which facilitates increased flight distance of fragments being driven by explosive gas expansion and is fed into parametric design software to enable advanced manufacturing to produce the casing. In some embodiments, an end use system includes an explosive interior core, a metallic casing composed of the optimized fragments described herein, and a polymer-based minimally thick buffer layer between the casing and explosive core.

[0005]In some implementations, assembly of the disclosed optimized fragment geometry casing for an explosive projectile device can include the manufacture of a metal casing composing general shapes-such as a right circular cylinder, sphere, filleted or rounded-edge right circular cylinder, prismatic, or other shape- and a user-specified inner and outer diameter wherein the interior is hollow; followed by the casting, matting, filling, or otherwise application of the polymer-based buffer layer on the interior surface of the casing which is minimally thick but ensures the interior is of a consistent diameter and qualitatively smooth surface roughness. The explosive core would then be cast, hand-packed, or otherwise made to fill the interior.

[0006]The explosive core comprises—for example—PBXN-110, LX-14, OCTOL, hand-packed C-4, or any other solid explosive (usually polymer-binded) that might be machined, cast, or hand-packed to fit within the inner diameter of the warhead and serve as the energetic core.

[0007]The disclosed technology uniquely allows a user-defined and programmatic optimized geometry design of the fragments of which the outer casing is composed. In some example embodiments of the optimized fragment geometry casing, each fragment is structured to have a “teardrop” or streamlined aerodynamic body geometry, that is to say, an ovular body characteristic of two radii of non-equivalent values joined with a “tail” portion which extends along a single vector. This geometry maintains axial symmetry, with the axis defined as from the tip of the “tail” of the teardrop along the center of the body to the final exterior surface of the ovular main body. This type of geometric design provides an individual fragment with uniquely low parasitic and induced drag characteristics which enable significantly reduced resistance in flight. With reduced resistance, each fragment is able to achieve greater distances at greater speeds and therefore improve warhead effectiveness by expanding the effective area without the need for additional energetic contribution upon initiation. Other example optimized fragment geometries, that may be applicable for other projectile objectives, are disclosed herein.

BRIEF DESCRIPTION OF THE DRAWINGS

[0008]FIG. 1 is a graphic showing several geometry cross-sections (a square, a circle, and a streamlined body) and their associated drag coefficients.

[0009]FIG. 2 shows a graph of the fragment mass and associated theoretical fragment distance across various fragment geometries and their associated drag coefficients.

[0010]FIG. 3 displays the warhead casing design with a teardrop fragment geometry, where input and output parameters control the design and ensuing effects.

[0011]FIGS. 4A-4C show an example warhead casing design with an elliptical fragment geometry, where input and output parameters control the design and ensuing effects.

[0012]FIGS. 5A-5C show an example warhead casing design with a bi-conic fragment geometry, where input and output parameters control the design and ensuing effects.

[0013]FIGS. 6A-6C show an example warhead casing design with a x-hedral fragment geometry, where input and output parameters control the design and ensuing effects.

[0014]FIGS. 7A-7C show an example warhead casing design with a glide body fragment geometry, where input and output parameters control the design and ensuing effects.

DETAILED DESCRIPTION

[0015]Casings of fragmentation warheads are generally designed to fragment at predetermined locations, producing projectiles of a certain average size, weight, and velocity. To ensure warhead effectiveness, fragments of a minimum size must be propelled and make contact with a target at a minimum threshold velocity. It is advantageous to have as many of these “ideal” fragments as possible as to increase the statistical likelihood that successful contact is made with the target given variable conditions.

Current Fragmentation Configurations Include the Following:

[0019]Disclosed are optimized fragment geometry designs for an explosive projectile device, such as a warhead, for improved and/or mission-specific performance, such increased flight distance of fragments driven by explosive gas expansion, increased penetration, and/or the like.

[0020]Example embodiments of the optimized fragment geometry design for an explosive projectile device are described below. In some embodiments in accordance with the present technology, the optimized fragment geometry casing includes a plurality of streamlined bodies tightly packed and positioned around the periphery of and comprising an outer casing of the explosive projectile device. In some embodiments in accordance with the present technology, the optimized projectile device includes an explosive interior core, a metallic casing composed of optimized fragment structures, and a polymer-based buffer layer (of minimal thickness) between the casing and the core.

[0021]For example, in some embodiments, each casing can include a matrix of these optimized geometry fragments orientated to construct shapes-such as a right circular cylinder, sphere, filleted or rounded-edge right circular cylinder, prismatic, or other shape—of consistent or variable interior and exterior diameter, of consistent or variable thickness, and of a consistent or variable height dependent on application. In some embodiments, fragments are organized such that the “tail” of each fragment is located on the interior surface and is aligned so that the tails point to the interior center axis or centerpoint of the warhead. Fragments are manufactured to be “stacked” along the circumferential plane which will then serve as the casing body, using variable methods ranging from placing one by one in an ordered, matrix fashion to being manufactured via advanced or additive methods.

[0022]“Stacking” efficiency, or how many fragments can be stacked within a given space is dependent on the smaller (outer) radii of each body. Fragments may be of uniform smaller radii or of variable resulting in different “shot lines” or vectors which fragments follow upon being explosively driven outward. Fragment bodies can be manufactured—by way of advanced subtractive manufacturing, additive manufacturing, casting, or other traditional manufacturing techniques—in one piece or mechanically connected/assembled (welded, brazed, cold sprayed, etc.) or bonded to one another into a metal-based web ensuring that the casing or pseudo-casing assembly is a complete surface with no voids between fragments. For example, this serves to also contain the expansion of explosive gases ensuring fragments are more efficiently driven outward on their predetermined/designed trajectory. In some embodiments, the casing may include a plurality of concentric layers of stacked fragments, wherein there exists a central core volume of explosive which, moving outwardly is surrounded in at least one dimension or more (radially, sandwiched, annular, etc.) by a set of one or more (stacked) fragment layers, or one or more (stacked) fragment layers with some non-explosive liner material in between.

[0029]The drag coefficient is the ratio of the force of drag exerted on an object with respect to the product of the kinetic energy of the fluid flow and the objects effective area facing the fluid flow. It is expressed, generally, by the formula below:

$C_D=\frac{F_D}{\frac{1}{2}{\rho }_a{u}^2{A}_{\mathrm{eff}}}$

[0030]FIG. 1 shows drag coefficients for different examples of fragment geometries. For a cube like structure, this could be as high as >1.0. For spheres, however, this can be improved by an order of magnitude (0.47), which implies a greater kinetic energy a greater distance, expanding the lethal footprint. In traditional warhead design and manufacturing, there is an unavoidable trade-off between simple low-cost manufacturing, fragment drag, and number of fragments. These variables are compared and contrasted in Table 1.

[0031]Due to manufacturing limitations and geometric complexity, previously we would have had to choose between those three options depending on system/cost constraints; however, ideally, fragment geometries would mimic “streamlined bodies” which have drag ratios less than 0.1 (e.g., ~0.04).

[0032]FIG. 2 shows a graph that demonstrates more streamlined fragments with less drag being associated with greater launch distances. Thus, warhead performance with respect to area of effect of fragments can be optimized and improved by reducing drag experienced by warhead fragments.

[0033]Leveraging advanced manufacturing techniques, such as metal additive manufacturing, structures can now be produced with a more streamlined geometries and diameters can be varied such that objects can be “packed”—or in this case printed—without extra assembly required and with a greater overall fragment count. In some embodiments, the casing fragments are manufactured from and/or are composed of any one or more of tungsten steel, titanium, steel alloys, tungsten alloys, 4000 series steel, and/or the like.

[0034]This enables the design to have a calculated performance improvement near two orders of magnitude in velocity at a set distance, which implies an extension of the lethal footprint by approximately two orders of magnitude—without the need for an improved or more expensive explosive. In some embodiments, the fragment design is also optimized to reduce a fragment tumbling outside its shot line or vector, given that the propulsion force upon a single fragment originates from a unconcentrated explosive core of the warhead (contrasted with a concentrated propulsion upon a bullet inside of a barrel, for example). To do so, the fragment design may include some consideration of weight distribution, in some embodiments, such that the center of gravity and center of pressure of each fragment is conducive to stable flight and would not unintentionally tumble during its trajectory.

[0035]FIG. 3 illustrates an example design in which a warhead casing comprises fragments with a teardrop geometry. As shown, a warhead 300 comprises an explosive core 302 and a casing 304 that encases or envelopes the explosive core 302. Based on detonation of the explosive core 302, the casing 304, or fragments thereof, are driven outward. The casing 304 is configured with pre-formed fragments 306 having a teardrop geometry, for example, including an ovular or elliptical body joined with a tail portion extending along a single vector. These pre-formed fragments 306 can be stacked or arranged to form the casing 304, and the casing 304 can include an epoxy, polymer, and/or the like the secure the pre-formed fragments 306 in their arrangement prior to detonation. As discussed above, the teardrop geometry is optimized to reduce drag, so that upon detonation of the explosive core 302, the pre-formed fragments 306 are launched a farther distance.

[0036]FIGS. 4A-4C illustrate an example design in which a warhead casing comprises fragments with an elliptical geometry. In FIG. 4A, a portion of the casing of a warhead 400 is shown, the casing having a plurality of pre-formed fragments 402 stacked or arranged to form the casing. As shown in FIGS. 4B-4C, each pre-formed fragment 402 has an elliptical geometry, where a cross-section of a pre-formed fragment 402 along a longitudinal axis is an ellipse with two radii, a and b. In some embodiments, the elliptical geometry of the pre-formed fragments 402 is defined or controlled by selecting, varying, and/or optimizing a ratio between the two radii (e.g., a/b). In some embodiments, the elliptical geometry of the pre-formed fragments 402 for a warhead casing has an a/b ratio between 2.8 and 3.2, between 2.5 and 3.5, between 2 and 4, or between 1 and 5. In some embodiments, a warhead casing has a plurality of pre-formed fragments 402 each having an elliptical geometry, with at least one pre-formed fragment 402 having a different a/b ratio than that of a different pre-formed fragment 402. For example, one section of the warhead casing includes pre-formed fragments 402 with a first elliptical geometry and another section of the warhead casing includes pre-formed fragments 402 with a second elliptical geometry. The first elliptical geometry may have a higher a/b ratio for reduced drag compared to the second elliptical geometry, resulting in one portion of the warhead casing having fragments that will be launched farther than a different portion. The absence and/or manipulation of a tail portion which may be seen to distinguish an elliptical geometry from a teardrop geometry alters the turbulent boundary layer that may form across the fragment control surface in flight, more specifically influenced by the length of said tail and stiffness of the taper angle. Integration of this tail may not be tractable given certain resolutions of available manufacturing methodologies and nor be optimal for fragments wherein reduced trajectory is a goal.

[0037]FIGS. 5A-5C illustrate an example design in which a warhead casing comprises fragments with a bi-conic geometry. In FIG. 5A, a portion of the casing of a warhead 500 is shown, the casing having a plurality of pre-formed fragments 502 stacked or arranged to form the casing. As shown in FIGS. 5B-5C, each pre-formed fragment 502 has a bi-conic geometry, where a fragment is composed of two cones having interfacing or co-planar bases. A total length of a fragment (summed heights of the two cones) can be defined by a first parameter a, and a radius of the interfacing or co-planar bases of the two cones can be defined by a second parameter b (or b/2). In some embodiments, the bi-conic geometry is characterized by a ratio a/b that is between 5 and 7, between 3 and 8, or between 2 and 10. In some embodiments, the bi-conic geometry is defined by a truncated cone or conic frustum and a second cone protruding from the truncation or the frustum plane, where the second cone and the truncated cone are characterized by different conic angles (e.g., θ₁ and (θ₁-θ₂) respectively). In some embodiments, θ₁ is between 20 degrees and 45 degrees, between 25 degrees and 40 degrees, or between 27.5 degrees and 33 degrees. In some embodiments, θ₂ is between 15 degrees and 35 degrees, between 20 and 30 degrees, or between 22 degrees and 27 degrees. In some embodiments, the bi-conic geometry is defined by a truncated cone or frustum, a second cone at the tip of the truncated cone or frustum, and a tail cone sharing a base plane with the truncated cone or frustum. Each of the parameters a, b (or b/2), θ₁, and θ₁ can be selected to optimize the geometry of at least one of the pre-formed fragments 502 for a particular effect (e.g., launch distance, penetration, impact radius or width). As discussed above, different fragments of a warhead casing can have varied bi-conic geometries. Bi-conic designs have geometry that facilitates excellent aerodynamic stability and likewise provides high-performance ballistic interaction up impact and subsequent penetration into a target body.

[0038]In the illustrated example of FIG. 5A, the bi-conic geometries of the fragments point outward from the center of the warhead. In some embodiments, some fragments may be pointed inward dependent on the spatial distribution of material density. In some embodiments, some fragments are pointed inward and others are pointed outward in order to pack more fragments into the casing.

[0039]FIGS. 6A-6C illustrate an example design in which a warhead casing comprises fragments with a x-hedral geometry. In FIG. 6A, a portion of the casing of a warhead 600 is shown, the casing having a plurality of pre-formed fragments 602 stacked or arranged to form the casing. As shown in FIGS. 6B-6C, each pre-formed fragment 602 has a x-hedral geometry, having an x number of vertices 603 or points around a circumference encircling a longitudinal axis of the fragment 602. For example, the illustrated example of FIG. 6C has a tetrahedral geometry with four vertices 603 around the fragment circumference, and FIG. 6B illustrates a cross-section at a vertex 603 around the fragment circumference. In some embodiments, a fragment 602 may have between four and twelve vertices 603 (between a tetrahedral geometry and a dodecahedral geometry), between four and eight vertices 603 (between a tetrahedral geometry and an octahedral geometry), or between four and six vertices 603 (between a tetrahedral geometry and a hexahedral geometry). In some embodiments, a warhead casing comprises fragments with an x-hedral geometry as an alternative to conical or elliptical geometries, which may be more difficult to efficiently manufacture with the desired curvatures. X-hedral geometry provides a balance of aerodynamic performance akin to that of the elliptical and teardrop geometries as before discussed, while possessing contextually superior penetration characteristics more similar to that of corner-striking cube fragments.

[0040]As shown in FIG. 6B, the x-hedral geometry can be defined by selecting parameters, including a (a length along a longitudinal axis), b or b/2 (a width/radius normal to the longitudinal axis), and θ₁. In some embodiments, θ₁ may be less than 60 degrees, less than 50 degrees, less than 45 degrees, or less than 40 degrees. In some embodiments, the x-hedral geometry is defined at least by a ratio a/b between 1 and 6, between 2 and 5, or between 2 and 4.

[0041]FIGS. 7A-7C illustrate an example design in which a warhead casing comprises fragments with an asymmetrical glide body. In FIG. 7A, a portion of the casing of a warhead 700 is shown, the casing having a plurality of pre-formed fragments 702 stacked or arranged to form the casing. As shown in FIGS. 7B-7C, each pre-formed fragment 702 has an asymmetrical glide body, defined at least by parameters θ₁, L, D, and w. In some embodiments, parameter θ₁ is between 5 and 10, between 5 and 15, between 3 and 18, or between 3 and 10. In some embodiments, the glide body is defined at least by a ratio L/D between 2 and 10, between 3 and 8, or between 5 and 7. In some embodiments, the glide body is defined at least by a ratio D/w between 0.125 and 1, between 0.25 and 1, or between 0.5 and 1. Asymmetric glide body based fragment geometries are such that the fragment does not just seek to minimize drag on its body, but is more conducive to generating lift, akin to that of a winglet. This enhances the fragment flight characteristics, and its tapered nose feature is also likely to facilitate enhanced penetration and or perforation behavior upon impact of a target.

[0042]Generally, a warhead casing can include fragments of any one of the above-described geometries or similar geometries, and in some embodiments, different fragments of a warhead casing can have different selected parameters of the same geometry and/or can have different geometries. Further, the fragments within the warhead casing can be oriented in different directions (e.g., pointing outward versus pointing inward) in order to increase fragment density, improving stacking arrangement, and/or the like. Warhead casing and application of geometries described above or similar, also need not be executed in such a way that there is axial symmetry. Rather, example embodiments may be executed in any fashion such that a volume of explosive is contained by a layer or multitude of layers of stacked fragments, with or without the presence of intermittent solid layers in at least one or more dimension.

Example Technical Solutions

[0043]In some embodiments in accordance with the present technology (example A1), an optimized fragment geometry casing for an explosive projectile device, comprising a plurality of streamlined bodies tightly packed and positioned around the periphery of and comprising an outer casing of the explosive projectile device.

[0044]Example A2 includes the optimized fragment geometry casing of example A1 or any of examples A1-A9, whereby, based on the optimized fragment geometry casing, features of the explosive projectile device are user-definable to customize their desired effects on a target.

[0045]Example A3 includes the optimized fragment geometry casing of example A2 or any of examples A1-A9, wherein the explosive projectile device includes a warhead.

[0046]Example A4 includes the optimized fragment geometry casing of example A2 or any of examples A1-A9, whereby the user-definable features of the warhead are programmable via a computer-implementable algorithm or program to produce a parametrically designed and optimized geometry design file, including but not limited to fragment sizes, shapes, packing densities, and arrangement about the casing.

[0047]Example A5 includes the optimized fragment geometry casing of example A2 or any of examples A1-A9, wherein the geometry of each streamlined body is user-defined via a computer-implementable program to produce a parametrically designed and optimized geometry design file.

[0048]Example A6 includes the optimized fragment geometry casing of example A4 or any of examples A1-A9, whereby the parametrically designed and optimized warhead casing design file is ingested by advanced manufacturing systems-including subtractive, additive, cast, or other more traditional methods—to produce said casing.

[0049]Example A7 includes the optimized fragment geometry casing of any of examples A1-A9, wherein each of the plurality of streamlined bodies is created via additive manufacturing with a steel alloy and/or a tungsten alloy.

[0050]Example A8 includes the optimized fragment geometry casing of any of examples A1-A9, wherein the streamlined bodies are structured in a teardrop shaping have an ovular body characteristic of two radii of non-equivalent values joined with a tail portion which extends along a single vector.

[0051]Example A9 includes the optimized fragment geometry casing of example A1 or any of examples A1-A8, wherein the plurality of streamlined bodies are tightly packed and positioned in a plurality of concentric layers that comprise the outer casing of the explosive projectile device.

[0052]In some embodiments in accordance with the present technology (example B1), a fragmentation projectile includes a core comprising an explosive material; and a casing enveloping the core, the casing composed at least by a plurality of pre-formed fragments in a stacked arrangement, wherein at least one of the pre-formed fragments has a geometry optimized for a reduction of a drag coefficient.

[0053]Example B2 includes the fragmentation projectile of any of examples B1-B11, wherein the geometry is optimized such that the drag coefficient is less than 0.47.

[0054]Example B3 includes the fragmentation projectile of any of examples B1-B11, wherein the casing comprises a backing layer comprising an epoxy or polymer that secures the plurality of pre-formed fragments in the stacked arrangement.

[0055]Example B4 includes the fragmentation projectile of any of examples B1-B11, wherein a first subset of the plurality of pre-formed fragments are optimized for a first drag coefficient and a second subset of the plurality of pre-formed fragments are optimized for a second drag coefficient.

[0056]Example B5 includes the fragmentation projectile of any of examples B1-B11, wherein the geometry of the at least one of the pre-formed fragments is a teardrop shape comprising an ovular body and a tail portion.

[0057]Example B6 includes the fragmentation projectile of any of examples B1-B11, wherein the geometry of the at least one of the pre-formed fragments is an elliptical shape that is optimized with respect to a ratio between a major axis length and minor axis length.

[0058]Example B7 includes the fragmentation projectile of any of examples B1-B11, wherein the geometry of the at least one of the pre-formed fragments is a bi-conic shape composed of a truncated cone characterized by a first conic angle and a tip cone characterized by a second conic angle and extending from a truncation of the truncated cone.

[0059]Example B8 includes the fragmentation projectile of any of examples B1-B11, wherein the geometry of the at least one of the pre-formed fragments is a hedron shape being optimized based on a selected number of planar faces.

[0060]Example B9 includes the fragmentation projectile of any of examples B1-B11, wherein the geometry of the at least one of the pre-formed fragments is an asymmetrical glide body being optimized to increase lift.

[0061]Example B10 includes the fragmentation projectile of any of examples B1-B11, wherein each of the plurality of pre-formed projectiles is additively manufactured from a steel alloy or a tungsten alloy.

[0062]Example B11 includes the fragmentation projectile of any of examples B1-B10, wherein the casing includes a plurality of concentric layers each comprising the pre-formed fragments.

[0063]In some embodiments in accordance with the present technology (example C1), an optimized fragment geometry casing for an explosive projectile device includes an outer casing of the explosive projectile device, and a plurality of streamlined bodies tightly packed and positioned around a periphery of the outer casing.

[0064]Example C2 include the optimized fragment geometry casing of any of examples C1-C7, wherein each streamlined body is user-defined and manufactured for a particular effect on a target.

[0065]Example C3 include the optimized fragment geometry casing of example C2 or any of examples C1-C7, wherein the geometry of each streamlined body is user-defined via a computer-implementable program to produce a parametrically designed and optimized geometry design file.

[0066]Example C4 include the optimized fragment geometry casing of any of examples C1-C7, wherein the explosive projectile device includes a warhead.

[0067]Example C5 include the optimized fragment geometry casing of any of examples C1-C7, wherein each of the plurality of streamlined bodies is created via additive manufacturing with at least one of a steel alloy or a tungsten alloy.

[0068]Example C6 include the optimized fragment geometry casing of any of examples C1-C7, wherein the streamlined bodies are structured in a teardrop shaping have an ovular body characteristic of two radii of non-equivalent values joined with a tail portion which extends along a single vector.

[0069]Example C7 include the optimized fragment geometry casing of any of examples C1-C7, wherein the plurality of streamlined bodies are tightly packed and positioned in a plurality of concentric layers that comprise the outer casing of the explosive projectile device.

[0070]In some embodiments in accordance with the present technology (example D1), an optimized fragment geometry casing for an explosive projectile device includes a plurality of streamlined bodies tightly packed and positioned around a periphery of an outer casing formed by the plurality of streamlined bodies.

[0071]Example D2 include the optimized fragment geometry casing of any of examples D1-D7, wherein each streamlined body is user-defined and manufactured for a particular effect on a target.

[0072]Example D3 include the optimized fragment geometry casing of example C2 or any of examples D1-D7, wherein the geometry of each streamlined body is user-defined via a computer-implementable program to produce a parametrically designed and optimized geometry design file.

[0073]Example D4 include the optimized fragment geometry casing of any of examples D1-D7, wherein the explosive projectile device includes a warhead.

[0074]Example D5 include the optimized fragment geometry casing of any of examples D1-D7, wherein each of the plurality of streamlined bodies is created via additive manufacturing with at least one of a steel alloy or a tungsten alloy.

[0075]Example D6 include the optimized fragment geometry casing of any of examples D1-D7, wherein the streamlined bodies are structured in a teardrop shaping have an ovular body characteristic of two radii of non-equivalent values joined with a tail portion which extends along a single vector.

[0076]Example D7 include the optimized fragment geometry casing of any of examples D1-D7, wherein the plurality of streamlined bodies are tightly packed and positioned in a plurality of concentric layers that comprise the outer casing of the explosive projectile device.

CONCLUSION

[0077]Implementations of user-defined, computer-based, and/or programmable subject matter and the functional operations, in accordance with the present technology described in this patent document, can be implemented in various systems, digital electronic circuitry, or in computer software, firmware, or hardware, including the structures disclosed in this specification and their structural equivalents, or in combinations of one or more of them. Implementations of the subject matter described in this specification can be implemented as one or more computer program products, i.e., one or more modules of computer program instructions encoded on a tangible and non-transitory computer readable medium for execution by, or to control the operation of, data processing apparatus. The computer readable medium can be a machine-readable storage device, a machine-readable storage substrate, a memory device, a composition of matter effecting a machine-readable propagated signal, or a combination of one or more of them. The term “data processing unit” or “data processing apparatus” encompasses all apparatus, devices, and machines for processing data, including by way of example a programmable processor, a computer, or multiple processors or computers. The apparatus can include, in addition to hardware, code that creates an execution environment for the computer program in question, e.g., code that constitutes processor firmware, a protocol stack, a database management system, an operating system, or a combination of one or more of them.

[0078]A computer program (also known as a program, software, software application, script, or code) can be written in any form of programming language, including compiled or interpreted languages, and it can be deployed in any form, including as a stand-alone program or as a module, component, subroutine, or other unit suitable for use in a computing environment. A computer program does not necessarily correspond to a file in a file system. A program can be stored in a portion of a file that holds other programs or data (e.g., one or more scripts stored in a markup language document), in a single file dedicated to the program in question, or in multiple coordinated files (e.g., files that store one or more modules, sub programs, or portions of code). A computer program can be deployed to be executed on one computer or on multiple computers that are located at one site or distributed across multiple sites and interconnected by a communication network.

[0079]The processes and logic flows described in this specification can be performed by one or more programmable processors executing one or more computer programs to perform functions by operating on input data and generating output. The processes and logic flows can also be performed by, and apparatus can also be implemented as, special purpose logic circuitry, e.g., an FPGA (field programmable gate array) or an ASIC (application specific integrated circuit).

[0080]Processors suitable for the execution of a computer program include, by way of example, both general and special purpose microprocessors, and any one or more processors of any kind of digital computer. Generally, a processor will receive instructions and data from a read only memory or a random access memory or both. The essential elements of a computer are a processor for performing instructions and one or more memory devices for storing instructions and data. Generally, a computer will also include, or be operatively coupled to receive data from or transfer data to, or both, one or more mass storage devices for storing data, e.g., magnetic, magneto optical disks, or optical disks. However, a computer need not have such devices. Computer readable media suitable for storing computer program instructions and data include all forms of nonvolatile memory, media and memory devices, including by way of example semiconductor memory devices, e.g., EPROM, EEPROM, and flash memory devices. The processor and the memory can be supplemented by, or incorporated in, special purpose logic circuitry.

[0081]While this patent document contains many specifics, these should not be construed as limitations on the scope of any invention or of what may be claimed, but rather as descriptions of features that may be specific to particular embodiments of particular inventions. Certain features that are described in this patent document in the context of separate embodiments can also be implemented in combination in a single embodiment. Conversely, various features that are described in the context of a single embodiment can also be implemented in multiple embodiments separately or in any suitable subcombination. Moreover, although features may be described above as acting in certain combinations and even initially claimed as such, one or more features from a claimed combination can in some cases be excised from the combination, and the claimed combination may be directed to a subcombination or variation of a subcombination.

[0082]Similarly, while operations are depicted in the drawings in a particular order, this should not be understood as requiring that such operations be performed in the particular order shown or in sequential order, or that all illustrated operations be performed, to achieve desirable results. Moreover, the separation of various system components in the embodiments described in this patent document should not be understood as requiring such separation in all embodiments.

[0083]Only a few implementations and examples are described and other implementations, enhancements and variations can be made based on what is described and illustrated in this patent document.