1180 results about "Mesh generation" patented technology

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 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.

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 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 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.

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 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 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.

The invention provides an SAR (synthetic aperture radar) echo simulating method based on GPU (graphics processing unit) parallel computing, overcomes defects on influencing SAR echo simulating speed and accuracy, and improves influencing SAR echo simulating speed. The method includes the steps of setting up scene scattering point mesh generation and making sure position relation of double antenna SAR and scene targets; building up backscattering coefficient model, and generating correlated backscattering coefficient pairs according to sight relation of double antenna SAR and ground scene so as to complete backscattering coefficient computing; calculating positioning echo signals in SAR irradiating area; performing convolution to positioning echo signals acquired in step 3 and transmitting signals to acquire current pulsing echo signals; and going through all positioning times to acquire SAR echo data influenced by double antenna in the whole scene.