1183 results about "Mesh generation" patented technology

Enables efficient correction of topological consistency of an input three-dimensional shape approximated in a spatial graph. Structured mesh generation systems of the present invention include: a topology determination apparatus for reading shape data from a shape data storage device to determine topological consistency and outputting data for solving a problem about topological consistency; a decomposable shape generation apparatus for reading the data outputted by the topology determination apparatus, changing a constraint condition of an integer programming problem solver to execute a shape correction process and outputting corrected shape data; and a structured mesh generation apparatus for reading the corrected shape data to generate a structured mesh.

Methods for generating information for displaying terrain on an aircraft display system that significantly reduces the computation and data load for producing the terrain display. This is accomplished through the use of intelligent level of detail control that computes and displays terrain and dynamic on-terrain perspective projection lines and distance rings aligned with the aircraft heading for depth perception and relative altitude awareness. The terrain details are processed and displayed in a manner that shows all significant terrain features, e.g., peaks, towers, and the like, but through the use of nonlinear error bound geometric morphing, coupled with triangle binary tree based terrain mesh generation, the polygon count, and thus the computational load, are significantly reduced, while visual fidelity is maintained.

The present invention provides an orthopedic surgery operation simulation system on the basis of force feedback, relating to the field of the virtual operation system development technology. The objective of the present invention is to allow users to truly sense biomechanical characteristics of human tissues so that the effect of operation training and the success rate of operations are improved. The orthopedic surgery operation simulation system comprises a virtual orthopedic operation simulation subsystem, an input module, a force feedback module and a display module. The virtual orthopedic operation simulation subsystem is configured to realize geometric modeling, mesh generation, biomechanics modeling and calculation thereof, collision detection, cutting and stitching and dynamic state visualization, force feedback calculation and the like of the human tissues required in the operation simulation process. According to the scheme of the invention, geometric modeling, mesh generation, biomechanics modeling and calculation thereof, deformation cutting, force feedback calculation and the like of virtual human tissues may be realized through independent programming on the basis of a visual studio development platform. The cost and the complexity of an operation system may be reduced.

The invention provides a video analysis based abnormal behavior detection method and system. The video analysis based abnormal behavior detection method comprises the following steps of extracting pedestrian foreground images from video frames; performing mesh generation on the video frames to divide the video frames into a plurality of mesh areas and setting the mesh areas in which the pedestrian foreground images are arranged to be movement areas; marking the movement areas through a nearest neighbor method and correlating the movement areas of the adjacent video frames; calculating light stream characteristics of the marked movement areas; obtaining a weighting direction histogram according to the light stream characteristics; calculating entropy of the weighting direction histogram; selecting a detection threshold value through a Gaussian mixture model, detecting whether an abnormal behavior is generated or not according to the detection threshold value and the entropy of the weighting direction histogram and updating the detection threshold value. The nested state machine based deduction process control method can automatically detect the abnormal behavior in a video scene, avoid the abnormal behavior disturbing the public plate order and endangering the public security and personal safety, reduce personnel workload and avoid potential risks caused by leak detection and error detection.

The invention discloses a method for accurately calculating a temperature field in an oil-immersed transformer. According to the method, a 3D physical model which completely corresponds to a real transformer in size and structure is built, scientific mesh generation is carried out on the physical model according to different characteristics of calculation methods, a finite volume method and a finite element method are combined for calculation, in other words, the finite volume method is used for calculating metal heat conduction of a winding and iron core portion and heat transfer in which fluid participates, and the accurate 3D calculation result of the temperature field in the oil-immersed transformer can be obtained; not only the temperature field of a winding or an iron core but also the temperature field of oil flow in the transformer, the temperature field of cooling fins and the temperature field of a transformer box can be accurately calculated, and the method has important and comprehensive referential significance in both design of transformers and actual operation of the transformers.

A method for evaluating fluid flows within a heterogeneous formation, crossed by one or more geometric discontinuities, comprising generating a hybrid grid from a CPG type grid and from structured grids having application, for example, in simulation of hydrocarbon reservoirs. The first stage locally deforms a CPG type grid into a non-uniform Cartesian grid. These local grid cell deformations correspond to the change from a so-called “CPG” frame of reference to a so-called “Cartesian” frame of reference defined by the deformation. These deformations are then quantified and applied to the structured grids so as to shift to the “Cartesian” frame. A hybrid g rid is then generated in the “Cartesian” frame from the two thus deformed grids. Finally, the hybrid grid is deformed to return to the “CPG” frame, prior to improving the grid quality, by optimization under quality control in the numerical scheme sense.

The invention discloses a single-photo-based human face animating method, which belongs to the field of graph and image processing and computer vision. The method is to automatically reconstruct a three-dimensional model of a human face according to a single human front face photo and then to drive the reconstructed three-dimensional model to form personal human face animation. The method uses a human three-dimensional reconstruction unit and a human face animation unit, wherein the human face three-dimensional reconstruction unit carries out the following steps: generating a shape-change model off-line; automatically positioning the key points on the human faces by utilizing an active appearance model; adding eye and tooth grids to form a complete human face model; and obtaining the reconstruction result by texture mapping. The human face animation unit carries out the following steps: making animation data of far spaced key points; mapping the animation data onto a target human face model by using a radical primary function; realizing motion data interpolation by using spherical parametrization; and generating the motion of eyes. The method has the characteristics of high automation, robustness and sense of reality and is suitable to be used in field of film and television making, three-dimensional games and the like.

A method having application for petroleum exploration or geological storage of generating a mesh of a faulted underground medium, comprising generating a hex-dominant mesh from faults and horizons in a form of a 3D triangulated surfaces. Each 3D triangulated surface is converted to a 2D triangulated surface onto which the faults are projected by an isometric unfolding technique. A regular two-dimensional grid pattern is generated for each 2D triangulated surface. The faults are accounted for by deforming quadrilaterals of the grid pattern intersected by projected faults. The deformed regular grid pattern is then converted to a 3D gridded surface and each quadrilateral which is crossed by a fault is converted into two triangles at a level of a diagonal. Finally, after iterating for all the 3D triangulated surfaces, the mesh is generated by creating links between the nodes of neighboring three-dimensional gridded surfaces with respect to the faults.

A spindle thermal distortion compensation method for a precision horizontal machining center comprises the steps as follows: a spindle model of a machine tool is simplified structurally; an ANSYS (finite element analysis software)-Workbench is utilized to perform mesh generation on a spindle entity model that is simplified, so as to obtain a spindle finite element model; and boundary conditions are calculated by combining with the practical spindle rotational speed, the environmental temperature, the coolant velocity, the flow rate, the inlet and outlet oil temperature and the like, and configuration is performed. Thermodynamics analysis and statics analysis are carried out in the ANSYS-Workbench to obtain more accurate spindle temperature field distribution and thermal deformation. Based on a finite element emulation result, the spindle temperatures in different positions and the spindle thermal deformations are analyzed at different rotational speeds by utilizing the Spearman rank correlation analysis, and spindle thermal key points are found out, so that references are provided to spindle thermal error tests and thermal error compensation. Finally, a thermal error compensation model is built up by utilizing a least squares method according to the key point temperature of the spindle and the thermal errors in the practical tests. Based on the thermal error compensation model, the spindle thermal error compensation is carried out by combining with thermal error compensation strategies of a numerical control system of the machine tool.

A method, mesh data structure and apparatus is disclosed for producing an improved / refined / derefined mesh of finite elements for a three-dimensional object showing boundaries and faces. The improvement / refinement method repeatedly searching, for consecutive sets of active target elements to be refined or improved, an associated submesh and set of terminal edges, the searching process not modifying the mesh data structure; then according to the point insertion method chosen, selection of the point or the points to be inserted between the midpoints of the terminal edges modified by some boundary considerations; inserting the selected point or points in the initial mesh; and then proceeding to the succeeding set of active target elements until an user-defined stopping criterion is achieved.The derefinement method, for each target vertex finding an associated set of neighbor vertices to be derefined; then eliminating each said vertex according an appropriate order such that the derefinement of said vertex allows to re-obtain a previous terminal edge whose bisection produced said vertex. The method, mesh data structure and apparatus of this invention allowing the parallel scaleable refinement / derefinement of the mesh by locally modifying sets of neighbor elements sharing the common longest-edge.

A mesh generation tool that is programmatically integrated with a system-level design and simulation environment, thereby enabling the direct generation of PDE solver input from a system-level design and simulation environment and a method for using the mesh generation tool are disclosed. Automatic mesh generation and optimization is improved by making available additional information about the nature and purpose of certain design components to the mesh generation tool. Specifically, the parameters of the components in the device schematic, which represent a user-defined decomposition of a larger MEMS design into smaller entities of clear physical purpose, are made available to the mesh generation tool. The link established between the system-level design and PDE analyses allows the user to move between the two levels of abstraction. The mesh generation tool retrieves information from the components and connectors of a schematic of a MEMS device, and produces a discrete element model suitable for numerical PDE analysis by the finite element (FEM) and boundary element (BEM) methods. A direct link from a schematic model to a mesh model helps the user to produce an optimal mesh for PDE analysis, thereby avoiding considerable unnecessary computation.

A system and method for automatic rigging of three dimensional characters for facial animation provide a rigged mesh for an original three dimensional mesh. A representative mesh is generated from the original mesh. Segments, key points, a bone set, and skinning weights are then determined for the representative mesh. The Skinning weights and bone set are placed in the original mesh to generate the rigged mesh.

The invention provides a spatial complex flexible structure multi-body system dynamics modeling and calculating method. The method comprises the steps of 101, building a three-dimensional model and giving parameters; 102, performing mesh generation on the model; 103, calculating a mesh unit generalized coordinate vector q and a generalized velocity vector; 104, building a mesh model constraint equation; 105, according to the mesh unit type, the generalized coordinate vector, the generalized velocity vector and the constraint equation, building a multi-body system dynamics equation on the basis of a first-class lagrange equation; 106, calculating the built multi-body system dynamics equation, and completing modeling calculating of the spatial complex flexible structure multi-body system dynamics problem. The simple and effective dynamics modeling method is provided for the flexible structure multi-body system, and the calculating efficiency is improved.

The invention provides a calculating method of ultimate strength checking of connection of a flange and a bolt. The method comprises the following steps: sampling a finite element analysis software as a platform to conduct modeling, conducting mesh generation with a finite element, setting load of a connection structure and boundary conditions, and conducting calculation to obtain the stress condition of the bolt, wherein the setting of the load of the connection structure and the boundary conditions is particularly as follows: the relation between an upper flange and a lower flange is the standard friction contact relation in a model; a high strength gasket and a bolt nut, and a high strength gasket and a bolt screw cap are connected by adopting a conode way; the high strength gasket and the upper flange, and the high strength gasket and the lower flange are connected by adopting a binding contact manner; the structural node space coordinates system of a tower cylinder restraining the bottom end of the lower flange is the degree of freedom in three directions of X, Y, and Z; a node is built in the center of the upper flange, and is connected with the top end of a tower cylinder model by multipoint restriction of a beam element, and an ultimate working condition load is applied in the center of the upper flange; each connection bolt applies bolt pretension force. The bolt stress intensity and danger positions calculated by the method are higher in accuracy.

Computer-implemented systems and methods are provided for generating accurate grids that can be used for simulation of highly complex subsurface reservoirs, such as fractured subsurface reservoirs. A representation of a fractured subsurface reservoir and an explicit discrete fracture represented within the fractured subsurface reservoir are provided. The representation of the fractured subsurface reservoir is decomposed into polyhedral cells. Interfaces between the polyhedral cells are selected to approximate the discrete fracture explicitly represented within the fractured subsurface reservoir. The selected interfaces are used to produce a grid that can be used for constructing a simulation model of the fractured subsurface reservoir.

The invention discloses a multiple-working-condition hydraulic design method for a guide vane type centrifugal pump. The multiple-working-condition hydraulic design method for the guide vane type centrifugal pump mainly comprises the following steps that specific speed solution is conducted on the design working conditions of the guide vane type centrifugal pump, and the design working condition with the specific speed as an intermediate specific speed is selected and designed; multiple-scheme design is conducted on an impeller and guide vanes through an experiment design method, and the CFturbo style is adopted; mesh generation is conducted on a model, numerical simulation is conducted on a scheme through CFX, the lift and the efficiency value are read, and function fitting is conducted between the lift and a flow; function fitting is conducted between the lift and the flow of a design parameter point, the coefficient of a fitting function is used as a design goal, input main geometrical parameters are used as input values, an approximate response model is established through the Kriging model, rapid computation is conducted on the approximate response model through a multiple-target genetic algorithm, and then the optimal value is obtained. By the adoption of the multiple-working-condition hydraulic design method for the guide vane type centrifugal pump, the requirement for multiple-working-condition hydraulic design of the guide vane type centrifugal pump can be met; the multiple-working-condition hydraulic design method for the guide vane type centrifugal pump can also be used for multiple-working-condition hydraulic design of other guide vane type centrifugal pumps.

The invention discloses a numerical simulation method for cavitation compressible flow shock wave dynamics and belongs to the field of numerical simulation of cavitation compressible flow and shock wave dynamics. A three-dimensional computing watershed based on three-dimensional geometric modeling software is established; a three-dimensional computing watershed mesh is divided based on mesh generation software; a cavitation compressible flow computational fluid dynamics model is established; an initial boundary condition is set to perform a three-dimensional computational domain flow field numerical computation; based on flow field post-processing software, the computational result is post-processed to obtain the unsteady evolution process of a multi-phase bubble structure. The numerical simulation method for cavitation compressible flow shock wave dynamics in the invention facilitates in-depth study of the cavitation physical mechanism, can be applied to the field of cavitation compressible flow and shock dynamics numerical simulation and solves related engineering problems. The cavitation compressible flow and shock dynamics numerical simulation engineering application area comprises hydraulic machinery, marine propellers, aviation turbo pump induction wheels, underwater supercavitation weapon applications.

A method, medium, and system for compressing and decoding mesh data in a three-dimensional mesh model is provided. The system for compressing and decoding mesh data in a three-dimensional mesh model includes a mesh data acquisition unit acquiring mesh data from a three-dimensional mesh model, a cluster mesh generation unit generating a plurality of cluster meshes by using the mesh data, and a local quantization unit quantizing geometry information of respective vertexes through application of respective local coordinate systems to the respective cluster meshes and generating quantized data of the respective vertexes included in the respective cluster meshes.

The invention relates to a method for macrosegregation numerical simulation of a casting, aiming at solving the problems of long computation time, low precision and unsuitability for predication of castings with large size or complex shapes in the traditional macrosegregation. The method comprises the following steps of: performing mesh generation on a selected dendritic crystal growth microcosmic computation field; computing dendritic crystal growth shapes during alloy solidification under different maximum nucleation densities from a microcosmic scale, and outputting a solid phase fraction-average dendritic crystal solid phase feature diameter curve; performing macro-scale mesh generation on the casting; computing a mass, momentum, energy and composition conservation equation from a macrocosmic scale; computing a solid phase fraction by using a Newton downhill method; and computing a pasty zone permeability model from a macrocosmic scale by adopting a linear interpolation technologybased on the solid phase fraction-average dendritic crystal solid phase feature diameter curve under a given nucleation density. The method disclosed by the invention is suitable for macrosegregationnumerical simulation in sand casting and metal mold casting of various sizes and complex shapes.

The invention relates to a semi-supervised learning indoor positioning method based on a support vector machine. The positioning method comprises the following steps: S1) carrying out mesh generation to the indoor positioning environment, and receiving the received signal strength (RSS) data of a WiFi (wireless fidelity) access point (AP) from a coverage area to each grid; S2) processing the collected data; and S3) positioning a mobile terminal. The semi-supervised learning indoor positioning method based on the support vector machine has the advantages of high real-time positioning precision, high use ratio of collected data and wide applicable scene.

The invention relates to an urban air quality grade predicting method based on multi-field characteristics. The method comprises a data preprocessing stage, a training stage and a predicting stage. In the data preprocessing stage, mesh generation is carried out to obtain a training sample, and a training data set is obtained. In the training stage, the optimal parameter of a conditional random field model is estimated, an optimal model shown in the specification is obtained, and the conditional random field model is output. In the predicting stage, the maximum output sequence, shown in the specification, of the conditional probability P(Y / X<f>) is obtained by combining the viterbi algorithm and the conditional probability model shown in the specification and obtained in learning of the training stage, and a prediction result is output. The AQI grade can be predicted more accurately, the AQI grade prediction in the following time quantum of all stations is carried out, and the requirement for selecting the time quantum with the high air quality to go out and take activities of people is met.

The invention belongs to the technical field of mechanical analysis and numerical solution of a three-dimensional structure and relates to a contact analysis method in three-dimensional mechanical finite element model analysis. The method comprises the steps of firstly modeling a target electron device structure; introducing a displacement boundary condition or a stress boundary condition to establish a corresponding geometric structure model; generating a contact relation between parts according to a mutual relation between the parts; then subdividing the established geometric structure model by use of a tetrahedral mesh; generating a joint surface mesh according to a surface mesh in a simulated area contact surface; and finally establishing a finite element general intrinsic equation of a target electron device in consideration of a contact problem by use of a finite element method, solving the equation to obtain a characteristic value and a characteristic vector, and post-processing to obtain a vibration modal frequency and a vibration model. Therefore, the contact analysis in modal analysis is realized and a high-precision numerical calculation result is obtained.

The invention discloses a radar echo signal simulator suitable for an onboard radar system. The radar echo signal simulator suitable for the onboard radar system comprises a parameter setting module (10), a data generation module (20), a data scheduling module (30), a digital to analogue (D / A) conversion module (40), a frequency mixing module (50) and an intermediate frequency oscillator (60). The radar echo signal simulator suitable for the onboard radar system combines an application scene model with radar parameters and antenna parameters, uses a clutter statistics distributing model and a power spectrum model to simulate a clutter series corresponding to a needed background topography, uses a mesh generation method to generate a clutter echo signal, and then uses position information of a needed sensitive area to generate a related target echo wave, and finally fuses the clutter signal with a target signal so as to generate a radar echo wave which conforms to test requirements and send the radar echo wave back to a test radar. The radar echo signal simulator suitable for the onboard radar system can be used in multiple links of research and development, production testing, performance detection and the like of a radar device on an airship, reduces frequency of outfield experiments to the utmost, saves experiment cost, and shortens a research period.

The invention discloses a direction-of-arrival estimation method based on sparse representation of a spatial smoothing covariance matrix. The method mainly solves the problems that the calculation amount is large, the performance of processing coherent signal sources is poor and consequently errors in passive location estimation are large in the prior art. The method comprises the implementation steps: (1) forming a uniform linear array by antenna receivers, (2) the spatial smoothing covariance matrix output by the array is calculated according to the spatial smoothing technology, (3) vectorizing the spatial smoothing covariance matrix to obtain sparse model vectors, (4) carrying out mesh generation on a spatial domain to construct a perfect base, (5) establishing a constrained optimization equation based on the sparse representation relation between the sparse model vectors and the perfect base, (6) solving the constrained optimization equation according to the convex optimization method to obtain an optimal estimation value, and (7) drawing a magnitude spectrum according to the optimal estimation value to obtain the value of direction of arrival. By means of the method, the calculation speed of passive direction finding is increased, and the performance of estimating the coherent signal sources at a low signal-to-noise ratio is improved. The method can be applied to target reconnaissance and passive localization.

The invention discloses a direction of arrival angle estimation method based on Sparse Bayesian learning. The direction of arrival angle estimation method mainly solves the problems in the prior art that the computation burden is heavy, the performance of the coherent signal source process is poor, and the errors in the passive location estimation are big. The direction of arrival angle estimation method comprises the following steps: (1) using an antenna receiver to form a uniform linear array, and sampling space signals to obtain observation data, (2) converting the observation data into real values and calculating a covariance matrix, (3) carrying out the mesh generation on airspace, and constructing a real value over-complete base, (4) establishing a sparse matrix equation according to the sparse presentation relationship of the covariance matrix and the over-complete base, (5) obtaining a most sparse solution of an unknown matrix variance through solving a matrix equation by employing the Sparse Bayesian learning, (6) drawing an amplitude spectrogram based on the one-to-one corresponding relation between the spares solution and the space angle, and obtaining the direction of arrival angle degree. According to the direction of arrival angle estimation method, the passive direction-determination calculating speed and the estimation performance on the signal direction angle when in fast and low number of beats are improved. The direction of arrival angle estimation method is applicable to the target reconnaissance and the passive direction-determination.

The invention discloses a method for simulating the wide-band electromagnetic scattering property of a conductor target. The method comprises the following steps that the geometric model of the conductor target is built, and mesh generation is conducted on the surface of the conductor target by a curved surface triangle unit; a time domain electric field integral equation of the conductor target is determined; a surface induction current in the time domain electric field integral equation expands through a space CRWG primary function and a time delay primary function; an expanding surface induction current expression is substituted into the time domain electric field integral equation, and then the time domain electric field integral equation in a discrete form is tested in a time and space mode so as to obtain a system impedance matrix equation; singularity integrals are eliminated to obtain a sparse expression of a impedance matrix; the equation of the impedance matrix is solved to determine the distribution of the time domain current of the surface of the conductor target, and wide-band electromagnetic property parameters of the target are obtained according to the distribution of the time domain current so as to finish simulation. The method for simulating the wide-band electromagnetic scattering property of the conductor target has the advantages of being high in simulation precision, little in required time and low in memory consumption, and has wide application prospect.

A method of mesh generation processing for a bounded domain is provided. The bounded domain is divided into constituent sub-domains with a portion of the sub-domains being assigned to each of a plurality of processors. The processors are operated independently and in parallel. Each processor (i) discretizes the closed boundary for each of its sub-domains to generate coordinates that are identical for each portion of adjoining sub-domain boundaries and that satisfy specific conditions that optimize a selected mesh generation technique, and (ii) generates a mesh for each sub-domain assigned thereto using corresponding ones of the coordinates and the selected mesh generation technique.

The invention discloses a liquid column separation-bridged water hammer simulation method based on three-dimensional CFD (Computational Fluid Dynamics). The liquid column separation-bridged water hammer simulation method comprises the following steps: by carrying out three-dimensional modeling and mesh generation, firstly, carrying out single-phase compressible stable-state calculation of a water body to obtain a stable-state fluid field; then carrying out liquid column separation gas-liquid two-phase transient flowing calculation; and finally, processing a computed result by using post-processing software. According to the liquid column separation-bridged water hammer simulation method, on the basis of simultaneously considering the compressibility of the water body and steam, the mass transfer between gas and liquid is considered, and liquid column separation types do not need to be distinguished, so that a mathematical model and a solving method thereof are simplified to a certain extent and the simulation accuracy is relatively high; and unreal pressure pulse similar with one-dimensional simulation is not formed, and visualization of primary formation, development and collapsing processes of a hollow hole in a liquid column separation process is realized.

A mesh generation tool that is programmatically integrated with a system-level design and simulation environment, thereby enabling the direct generation of PDE solver input from a system-level design and simulation environment and a method for using the mesh generation tool are disclosed. Automatic mesh generation and optimization is improved by making available additional information about the nature and purpose of certain design components to the mesh generation tool. Specifically, the parameters of the components in the device schematic, which represent a user-defined decomposition of a larger MEMS design into smaller entities of clear physical purpose, are made available to the mesh generation tool. The link established between the system-level design and PDE analyses allows the user to move between the two levels of abstraction. The mesh generation tool retrieves information from the components and connectors of a schematic of a MEMS device, and produces a discrete element model suitable for numerical PDE analysis by the finite element (FEM) and boundary element (BEM) methods. A direct link from a schematic model to a mesh model helps the user to produce an optimal mesh for PDE analysis, thereby avoiding considerable unnecessary computation.

An embodiment of the invention discloses a method and a device for simulating dynamic discrete cracks of an oil deposit. The method comprises the following steps of performing the mesh generation on the oil deposit so as to obtain meshes of the oil deposit; further dividing the meshes of the oil deposit into multiple secondary meshes; calculating conductivities between matrices, between each matrix and cracks as well as between the cracks, calculating a fluid exchange coefficient between a storage layer and a pitshaft, and further obtaining pressure and saturability under every time step; building discriminant criteria of crack formation and dynamic extension in the water injection process, building coupling relationships between natural cracks and water injection dynamic cracks as well as between the natural cracks and pressure cracks, and judging crack extension situations at different time points; dynamically dividing the meshes by means of taking an extended new crack as a boundary condition, and meanwhile assigning the attribute information of the new crack to a mesh boundary so as to update the mesh boundary; correcting mechanical parameters of the oil deposit and rocks, performing the historical data fitting, and calculating the saturability and pressure situation of the present time step.