99 results about "Quadrilateral grid" patented technology

Methods for finite-difference-based inkjet simulation enable more precise control of ink droplet size and shape. A discrete transformation (mapping) is constructed so that a quadrilateral grid in physical space is transferred to the uniform square grid in a computational space. Since the grid in the computational space is square, numerical finite difference differentiation can be easily done. Governing partial differential equations, including a viscosity term, a surface tension term, and a level set convection equation for two-phase flows, are derived on the quadrilateral grid and then transformed to the computational space for application on the uniform square grid. A stable and powerful numerical algorithm is developed to solve the derived and transformed equations to enable finite-difference-based ink-jet simulation.

The invention discloses a calculating method for dynamic pollution field of open water body emergent pollution accident. The method provided in the invention comprises the following steps: 1) determining area coverage the model calculates according to the position of a pollution source and basic flow field characteristics of the open water body; 2) respectively obtaining data 1, data 2, data 3, data 4 and data 5; 3) respectively inputting the data 1-5 into a software and respectively generating a corresponding data file. The experiments prove that: by applying the above technical scheme, the calculating method has advantages of using structureless trilateral and quadrilateral grids to solve for a two-dimensional or three-dimensional model and being suitable to any region's mesh dissection and solution.

A central difference scheme, on which a coupled level set projection method is based, is extended to quadrilateral grids on axi-symmetric coordinate systems. The level set projection method is incorporated into a finite-difference-based ink-jet simulation algorithm. The extension involves modification of the Navier-Stokes equations and the level set convection equation. Moreover, the velocity and level set correctors in axi-symmetric coordinate systems should be “recovered” to point values before being projected. Numerical differentiation and integration in the central difference scheme are done in the computational space. The inventive algorithm may be embodied in methods, apparatuses, and instruction sets carried on device-readable mediums.

The invention discloses an electrical property prediction method of an active reflector antenna, which mainly solves the problem that the electrical properties are difficult to be told in advance when adjusting a panel of the active reflector antenna. The method has processes of: obtaining an initial pose of the active panel based on basic structure parameters of the antenna and the partitioning condition of the active panel; calculating the phase difference of sampling nodes selected on a single panel to synthesize the phase difference of the single panel and finally synthesize the phase difference of the whole antenna reflector; calculating the electric field distribution in the antenna far zone by utilizing gauss integral formulas for quadrilateral elements and getting a directional pattern and related electrical parameters of the antenna; judging whether the electrical parameters can meet the design requirements of the antenna, if can, outputting the electrical parameters and pose information of the single panel, if not, adjusting the active panel and repeating the previous analysis process until the electrical properties meet the demand. The simulation result shows that the method can be applied to the electrical property predictions of antennae with different frequency ranges and be used to guide the panel adjustment of the active reflector antenna and the electrical property analysis.

The present invention is directed towards systems and methods for simulating and analyzing viscoelastic fluid flow. The fluid flows through a channel and is ejected from a channel. The fluid has an interface between a first fluid and a second fluid. The method includes performing finite difference analysis and using a level set projection method to solve equations governing the viscoelastic flow of the fluids through the channel. The equations governing the viscoelastic flow include an azimuthal velocity term that is an approximate description of the azimuthal flow of the fluid. The equations governing the viscoelastic flow also include an approximation of the stress experienced by the fluids being simulated. The equations governing the viscoelastic flow include an advection term that includes an azimuthal velocity term. The finite difference analysis used to solve the governing equations includes a second-order Godunov type upwind scheme to update the advection terms over time. The level set for the first and second fluids is updated periodically during the simulation.

The invention relates to a generation method of quadrilateral grids of a geometric model with any internal feature constraints, which outstandingly enhances the generation quality and efficiency of the quadrilateral grids and has convenience and practicability. The generation method comprises the following steps of: (1.1) building an entitative geometric model according to an entity to be analyzed by utilizing a computer; and determining the shapes and the positions of constraint lines and density lines of the entitative geometric model, the positions of constraint points and density points and the range and the inner and outer boundaries of each region; (1.2) generating grid nodes on the inner and outer boundaries, the constraint lines and the density lines of the entitative geometric model according to grid size information set by a user, and numbering the grid nodes; viewing the constraint points and the density points as newly generated grid nodes, and numbering the newly generated grid nodes; (1.3) viewing the constraint lines, the density lines, the constraint points and the density points as internal cavities with areas of zero, generating node rings on the inner and outer boundaries of each region, and transforming a multiply connected region with the internal feature constraints into a simply connected region; (1.4) dividing the quadrilateral grids in each region; and finally generating the quadrilateral grids with the internal feature constraints.

The invention discloses a method for generating a quadrilateral finite element grid based on a three-dimension entity model, which is applicable to the preprocessing stage of the finite element analysis. The method comprises the steps of encapsulating a three-dimension entity model in a cuboid containing box adapting to the shape of the model, subdividing the cuboid containing box into a certain quantity of cubic units, deleting the cubic units disjointed with the surface of the three-dimension entity model, dividing each cubic unit intersected with the surface of the three-dimension entity model into six mutually independent quadrilateral facets, deleting quadrilateral facets intersected with and arranged in the three-dimension entity, projecting four nodes on each quadrilateral facet arranged outside the three-dimension entity model onto the surface of the model and combining four new nodes obtained after the projection into a new quadrilateral facet, combining all the quadrilateral facets to obtain the quadrilateral grid of the three-dimension entity model and storing the generated quadrilateral grid data into a user-defined data file in the DPM format.

The invention relates to a reestablishing method for a smooth curved surface on an arbitrary quadrilateral grid. The reestablishing method comprises the following steps: 1) generating boundary curves of quadrilateral regions; 2) as for each quadrilateral region, generating a B spline curved surface by fitting the boundary curves and internal data points; 3) carrying out C<2> compatibility adjustment at the regular vertex and G<1> compatibility adjustment at a singular vertex; 4) carrying out C<2> stepless control on a regular boundary; 5) carrying out approximate G<1> stepless control on an irregular boundary. The reestablishing method for the smooth B spline curved surface on the arbitrary quadrilateral grid simplifies the solution, improves the efficiency, and promotes the reestablishing effect.

The invention relates to a hexahedron finite element grid partitioning method for simulating screw-thread fit. The method comprises the following steps: firstly, according to a distance change rule ofa thread surface and a thread axis, determining a single-layer thread cross section contour line, and using a minimum feature of a thread as the axial finite element grid size; and according to a rotation angle relation between the number of the grid layers axially partitioned within a single thread pitch and the adjacent layer, determining the circumferential finite element grid number, throughthe quadrilateral grid stretching of the bolt thread end face, forming a single-layer hexahedral grid, and performing the copy, the rotation and the node replacement on the single-layer hexahedral grid so as to obtain a single-pitch bolt hexahedral grid model; finally, according to the male-female thread tooth number, performing the copy and the translation on the single-pitch grid so as to obtaina hexahedral grid model of the whole bolt thread part. So, the hexahedron finite element grid partitioning method does not need to build a solid three-dimensional model of a male-female thread, and does not need a lot of the node coordinate calculation.

The invention discloses a preprocessing method for deformation data of a panel of a reflector antenna. The method takes deformation data of the reflector antenna as a processing object, and selects different data preprocessing methods according to different data types in engineering of a sector panel sampling point three dimensional coordinate, a triangular unit nodal coordinate and a quadrilateral unit nodal coordinate; an area coordinate and a polar coordinate are introduced to simplify an integral domain of any unit; the efficiency of the numerical integration is improved by using the Gauss integral formula; the number of lobes of a directional diagram are evaluated by referring to the half power lobe width; the number of discrete points of each lobe are picked up to determine the discrete precision of the directional diagram; according to the discrete precision of the directional diagram, the numerical integration calculation is repeated, and a complete far field directional diagram of a deformed reflector antenna is drawn in the end. A simulation result shows that the invention can not only effectively reduce the data processing time, but also improve the calculating precision of the antenna directional diagram; thereby the preprocessing method can be applied to the preprocessing of the deformation data of the reflector antenna under a plurality of engineering situations.

The invention provides a method of clipping quadrilateral grids of a coal seam by a triangular grid of an open-pit mine stope, and relates to the technical field of coal seam geology. According to themethod, firstly, the quadrilateral grids of coal seam roof and floor interfaces and the triangular grid of the open-pit mine stope are generated; then intersecting-line polygons obtained by intersection of the triangular grid and the quadrilateral grids are generated, and sorted counterclockwise to obtain clipping polygons; and finally, the clipping polygons are used to clip the quadrilateral grids of the coal seam roof and floor interfaces to realize updating for a coal seam geology model. According to the method of clipping the quadrilateral grids of the coal seam by the triangular grid ofthe open-pit mine stope provided by the invention, the problem that intersecting lines of quadrilateral curved surfaces and triangular surfaces are space curves is effectively solved, and practical application is enabled to be realized. The method of directly utilizing the triangular grid to clip the quadrilateral grids highly efficiently realizes, on the premise of not increasing a storage amount, operations of clipping the quadrilateral grids by the triangular grid.

The invention provides a method for parameterizing a quadrilateral grid in a conformal mode. The method is used for directly parameterizing a curved surface of the quadrilateral grid, and comprises the following steps that S11 a quadrilateral grid is input, S12 borders of the quadrilateral grid are parameterized with the length maintained to obtain a border condition, S13 an angle system of the quadrilateral grid is solved to obtain angle input of a conformal energy function, and S14 the conformal energy function is constructed, and the quadrilateral grid is grid-parameterized according to the conformal energy function. According to the method for parameterizing the quadrilateral grid in the conformal mode, the quadrilateral grid can be directly parameterized, not every quadrilateral needs to be divided to two triangles, and the curved surface is parameterized according to a triangular grid parameterizing method.

The invention provides a distortion correction method applied to a flat-panel charge coupling device (CCD) detector. The method comprises the following steps of: acquiring a dot template image by the flat-panel CCD detector; acquiring the neighboring relation of various dots in the dot template image by a grid search method; constructing quadrilaterals by using circle centers of each four dots so as to construct dot quadrilateral grids of the dot template image; and finally, acquiring distortion factors through coordinate transformation, and realizing the correction of a medical image by using the distortion factors and a cubic interpolation method. By the method, the solving operation amount of the distortion factors is appropriate, so that the efficiency is high; and before an imaging mode of a camera is obtained, an imaging model and the characteristics of the camera are not required to be pre-evaluated.

The invention belongs to the field of reverse finite element analysis, and relates to a low-rigidity workpiece assembly deformation prediction method based on point cloud data. The method includes: Firstly, adopting a three-dimensional laser scanner to scan a to-be-tested low-rigidity workpiece, obtaining point cloud data of surface information of the to-be-tested low-rigidity workpiece, and carrying out point cloud simplified filtering processing; Secondly, completing three-dimensional transformation of point cloud coordinates in a three-dimensional coordinate system, rotating a normal vectorof the point cloud to be perpendicular to an xy plane, enabling a straight line to be parallel to an x axis and enabling a boundary of the point cloud to be parallel to the x axis, and completing two-dimensional grid division by utilizing the xy plane coordinates; adopting a radius search method and a least square method to obtain a point cloud ordered representation point of the low-rigidity workpiece; And finally, forming a quadrilateral grid by taking every four representative points as a group, outputting a required grid format, and inputting the quadrilateral grid format into finite element analysis software for constraint and displacement loading to obtain the shape change of the assembled low-rigidity workpiece. The method has the characteristics of rapidness and accuracy, and theconnection assembly time and cost are effectively saved.

A patch antenna in a wireless communication system includes a patch antenna unit positioned at a predetermined point on a substrate; a first cover of a high-gain metamaterial of a different structure positioned over the patch antenna unit at a first distance from the substrate on which the patch antenna unit is positioned; and a second cover of a metamaterial of an identical structure positioned over the first cover at a second distance from the first cover. The first cover has a quadrilateral grid formed only on an outer periphery of a dielectric surface of the first cover.

The invention discloses an equipotential lightning protection auxiliary device for a small-scale industrial control room. The equipotential lightning protection auxiliary device is used in combination with a lightning protector. The equipotential lightning protection auxiliary device is characterized by specifically comprising a metal strip (1) and a metal grid (2), wherein the metal strip (1) is laid along a wall and an equipment cabinet (3); the metal grid (2) is in electric connection with the metal strip (1); the equipotential lightning protection auxiliary device is connected with a reserved grounded cable in the small-scale industrial control room through a cable; particularly, the metal strip is a copper bar of which the cross section is 20-50 mm in length and 1.5-6 mm in width; the metal grid (2) is particularly an equipotential grid composed of copper bars which are arranged in an intersection connection manner; the metal grid (2) is a parallel quadrilateral grid which is 300-2000 mm in edge length; and normal uncharged conductors in the industrial control room are all connected with the metal strip (1) or/and the metal grid (2) through electric wires. Compared with the prior art, the equipotential lightning protection auxiliary device is standard in structural design, good in operability and excellent in technical effect.

The invention belongs to the technical field of radiant electric heating, and particularly relates to a curved surface graphite heater design method, which comprises the steps of performing mesh generation on an ideal heating curved surface of a test piece to generate a finite element model comprising a plurality of quadrilateral units or coexistence of the quadrilateral units and triangular units; carrying out interpolation processing, so as to enable each quadrilateral unit and each triangular unit to correspond to one node plane respectively, and obtaining a coplanar node set composed of athree-node group and a four-node group; in the three-dimensional processing software, generating intersection lines of adjacent reference planes, and generating triangular, quadrilateral and polygonalgraphite flake reference design surfaces through the intersection lines; cutting the edge of the reference design surface of the graphite flake to form a graphite heating surface, and finally designing a heating circuit for the graphite flake of each heating surface according to the heat flow load input requirement required by the test. According to the method, the stability and controllability of large heat flow output of the conformal graphite heater in a complex curved surface appearance structure heat intensity test are achieved.

Embodiments of the present invention provide a finite difference method, a finite element projection, and a non-finite-element implementation of the finite element projection for solving the incompressible continuity equation on quadrilateral grids to obtain pressure and fluid velocity. An exemplary apparatus for simulating and analyzing the flow of an incompressible fluid is also provided. More particularly, embodiments of the present invention provide a non-finite-element-method (non-FEM) to implement the finite element projection to obtain a linear system whose coefficient matrix has an average bandwidth of five, in comparison to the finite difference scheme using conventional finite element projection and implementation with a bandwidth of nine. A two-dimensional-five-point-stencil-based non-FEM discretization is formulated to enforce the incompressible continuity equation. A shape function that is different from a weighting function used in the incompressible continuity equation is utilized to guarantee the five-point-stencil discretization is possible. The smaller bandwidth of the non-FEM scheme requires less computing resources and can compute the results in a reduced time duration, due to the simpler matrix to solve.

The invention discloses a three-dimensional dynamic rendering display method for flood risk analysis result data, and the result data is obtained based on an irregular quadrilateral grid, and the method comprises the steps: 1, screening effective grid data, and obtaining the attribute data of an effective grid; 2, calculating elevation values of edge element center points and grid vertexes; 3, generating planar and spatial triangular terrain grids; 4, based on the planar triangular mesh, slicing the DOM data and stretching and mapping the DOM data to the spatial triangular mesh to form the three-dimensional terrain image scene of the spatial triangular mesh; 5, calculating water level values of edge element midpoints and grid vertexes; 6, generating a spatial triangular mesh of the water level; 7, generating the spatial triangular mesh in the step 3 into data in a 3DTile format, and rendering a terrain image scene in Cerium together with the DOM image slice in the step 4; and 8, performing texture mapping and stretching on the water level space triangular mesh in the step 6 in the interval time sequence, and performing dynamic rendering. The method is high in accuracy and good in visualization effect, and accords with the actual situation.

The invention discloses an automatic decomposition method for a two-dimensional structure grid of a multi-inner-hole part based on a neural network. The introduction of a manual link in the existing block structured grid generation greatly reduces the grid generation efficiency. The method comprises the following steps: firstly, making a sample set for neural network learning two-dimensional region decomposition, and training a neural network model through position information of each grid point in the sample set and frame vector labeling information of each frame; performing neural network prediction on the prediction sample data of the multi-inner-hole part of which the structure grids are to be divided, and processing the prediction sample data by utilizing frame vector labeling information predicted by the neural network to obtain final regional decomposition data; and finally, generating a quadrilateral grid of the multi-inner-hole part of the to-be-divided structure grid by utilizing a mapping method. The method can achieve the quick automatic region decomposition of a new model, and is of great significance to the quick and accurate simulation analysis of a multi-inner-holepart.

The invention belongs to the technical field of computer animation and discloses a multi-precision grid refinement method based on CNN cloth wrinkle recognition, and the method comprises the steps: firstly building a human body model, carrying out animation simulation, extracting a key animation frame, carrying out the segmentation of a wrinkle part, enabling the segmented model to serve as the input of a convolutional neural network, and obtaining the recognition of wrinkles through CNN training so that refinement is carried out on the identified wrinkle part by using a pixel grid; and finally, converting the refined quadrilateral grid into a triangular grid, and carrying out cloth simulation. Compared with a traditional wrinkle recognition method based on curvature calculation, the wrinkle recognition method has the advantages that the wrinkle recognition speed is increased while accurate wrinkle recognition is guaranteed. A pixel refinement method is adopted to refine the grid, so that the grid is finer, and the simulated cloth is more vivid.

The invention discloses a method based on mobile terminal curtain image model generation. The method relates to the technologies of image deformation, intelligent decoration and the like. The Method based on mobile terminal curtain image model generation comprises the steps of regarding a picture to be made into a curtain as an original image, and dividing the original image into a regular quadrilateral grid, wherein pixel points on the grid are in one-to-one correspondence with pixels on the original image, vertices of the grid are control points that control the deformation and distortion ofthe grid, the original image changes along with the change of the shape of the grid, and the control points drive the gird to change according to a deformation formula, thus the original image changes and further generates a curtain model. The method utilizes the touchable property of a mobile terminal and an image processing technology, establishes the curtain model, and provides the user with acustomizable curtain model.