133 results about "Boundary element method" patented technology

The invention provides a numerical value simulation method of the vibration and acoustic characteristics of a speaker. The method comprises the following steps of: firstly, drawing a 3D (Three-Dimensional) geometric model diagram of the speaker by using 3D drawing software; then, adding the 3D geometric model diagram of the speaker to meshing software to mesh the 3D geometric model diagram into body elements, defining element types, materials and boundary conditions and applying a load to acquire a finite element model; establishing a boundary element model matched with the finite element model; and finally, solving the finite element model with a finite element solver to acquire the vibration characteristics of the speaker, and solving the boundary element model with a boundary element solver to acquire the acoustic characteristics of the speaker, wherein the vibration characteristics include the natural frequency, the vibration mode (vibration type), the displacement, the strain and the stress, and the acoustic characteristics include a frequency response curve and a directivity curve.

An interactive system and method of operating the system to define and evaluate a model of a hydrocarbon reservoir. The reservoir model is defined from extrinsic information such as seismic surveys, well logs, and the like, and is based on elements of formation regions, connections among the regions, wells, and perforations. A boundary-element method is used to determine pressure interference responses, corresponding to the pressure at a perforation in response to a single perforation producing fluid at a unit flow rate. These pressure interference responses are then convolved with measured well flow rates obtained during production to arrive at estimates of the wellbore pressure at one or more wells of interest. The estimated wellbore pressure can be compared with downhole pressure measurements to validate the reservoir model, or to provoke the user into modifying the model and repeating the evaluation of the model.

The invention discloses a designing method for a gradient coil of a self-shielding superconductive nuclear magnetic resonance imaging system.The designing method comprises the steps that firstly, three-dimensional continuous triangular mesh dividing is performed on a main coil framework region and a shielding coil framework region, and an axial magnetic induction intensity coefficient matrix generated by mesh nodes in the main coil framework region and the shielding coil framework region on a target field point is calculated according to a boundary elements method; secondly, an optimization calculation model is built through a regularization method, wherein the optimization calculation model comprises two parts, the first part is deviation between the axial magnetic induction intensity generated by the mesh nodes in the main coil framework region and the shielding coil framework region on a target field point and the expected target magnetic induction intensity, the second part is the quadratic sum of the flow function curvature of the mesh nodes, and flow function values of the mesh nodes in the main coil framework region and the shielding coil framework region are obtained through solution; lastly, actual winding distribution of the gradient coil is obtained through a flow function method.

The invention provides an extra-high voltage direct current line boundary element method adopting polar wave wavelet energy ratio, belonging to the technical field of relay protection of electric power systems. The method comprises the following steps: when the direct current line has fault, computing the anode line polar wave voltage and the cathode line polar wave voltage according to the direct current voltage and direct current of the two poles measured in the relay location; selecting the discrete polar wave voltage signal with sampling sequence length of 200 after fault to undergo wavelet transform to obtain a series of high/low frequency polar wave voltage wavelet transform parameters and computing the modules of the high/low frequency polar wave voltage wavelet transform parameters; computing the ratio of high/low frequency energy of polar wave voltage after extracting the high/low frequency components of polar wave voltage according to the obtained modules; and distinguishingthe area fault from the out-area fault according to the ratio of high/low frequency energy. Lots of simulation results show the method has good effect.

The object of the present invention is to realize a low-invasive underground exploration apparatus, system, and method which are capable of specifying the kind, three-dimensional position, and amount of a substance present in the ground. The underground exploration apparatus, system, and method includes: measuring, at multiple points, a high frequency voltage that appears upon conduction of high frequency current through the ground to obtain measurement results at two or more frequency levels; employing an ground model using the finite element method, the boundary element method, an impedance network, or the like to estimate a substance in the ground by changing unknown quantities of the ground model such as local dielectric constant and electric conductivity so as to make an error between the actual measured value and the calculated value smaller; and displaying input information of the ground model and results of the estimation processing two-dimensionally or three-dimensionally.

Long Elements Method (LEM) for real time physically based dynamic simulation of deformable objects. The LEM is based on a new meshing strategy using long elements whose forms can be straight or arbitrary. The LEM implements a static solution for elastic global deformations of objects filled with fluid based on the Pascal's principle and volume conservation. The volumes are discretised in long elements, defining meshes one order of magnitude smaller than meshes based on tetrahedral or cubic elements. The LEM further combines static and dynamic approaches to simulate the same deformable medium, allowing modeling a three-dimensional internal state at any point inside the deforming medium from a reduced number of explicitly updated elements. Complex elastic and plastic deformations can be simulated in real time with less computational effort. The LEM is particularly useful in real time virtual interactions, soft tissue modeling, and graphic and haptic rendering.

The invention discloses a method for predicting hydraulic noise of a centrifugal pump. The method is characterized in that a model pump is subjected to three-dimensional modeling, an unsteady constant value analogue value is calculated in an ANSYS-CFX, a centrifugal pump internal flow induced noise sound field is solved by combining LMS Virtual. Lab Acoustics. Based on a Lighthill acoustic analogy, an analogy method for solving the centrifugal pump internal flow induced noise sound field through a mixed method by taking a blade surface dipole as a pump internal acoustic source is provided. Meanwhile, a volute acoustic scattering effect is considered, and inner and outer acoustic models are established by taking a volute as a boundary. Meanwhile, according to pump internal flow induced noise characteristics, a direct boundary element method is selected to solve the sound field, and the acoustic characteristics of the centrifugal pump at the blade frequency and harmonic frequency are studied. A trend of the sound field along with flow change can reflect the actual condition of the model pump, so a numerical simulation method can be used as a method for predicting the centrifugal pump fluid induced noise, and a theoretical design basis is provided for designing a low-noise centrifugal pump.

The invention discloses a water injection seepage flow in coal and rock mass zoning, damage-stress coupling numerical simulation method, according to the geological survey results, the coal seam modelis established; water injection seepage flow in coal and rock masses in non-mining affected area and mining affected area is simulated by zoning. In the non-mining influence area, the program can judge whether the coal body is deformed or even fractured under the action of water pressure stress by calculating and comparing the tensile and shear moments of each grid. At the same time, the meshlessmethod is used to simulate the fracture process of coal mass and the boundary element method is used to simulate the seepage process, which combines the advantages of the two methods on the micro-scale. In the mining-affected area, N-S equation and Darcy's law to accurately simulate the coal and rock mass water injection process in the coal and rock mass damage and moisture transport law. A soliddata basis for coal seam water injection is provided, greatly reducing the possibility of coal broken into dust particles, reducing the production of coal dust, ensuring the safety of coal seam mining.

A method of identifying a flaw in a part is provided that includes vibrating a part to induce heat. The heat originates in any flaws in the part. A thermal image is obtained using, for example, an infrared camera. A mathematical representation of the thermophysics, such as the heat conduction or thermal energy equations using the boundary element method or finite element method is used to identify a source and an intensity of the heat identified with the thermal image. Using the source and intensity of the heat, flaw characteristics for the part can be determined. The method is employed using an inspection system that includes a vibration device for vibrating the part. An imaging device, such as an infrared camera, measures temperature on the surface of the part. An assumption is made or additional measurements are taken to obtain values for surface flux or surface heat transfer coefficients. A processor communicates with the imaging device for receiving the surface temperature. The processor includes computer memory having part characteristics and mathematical equations. The processor uses the measured surface temperature, assumed or measured heat flux or heat transfer coefficients, part characteristics and mathematical equations to determine the flaw characteristics in the part.

The invention relates to a universal method of boundary modeling based on distinct element method, which is applicable to analyze and evaluate the service performance of a mechanical part through distinct element method. The technical solution comprises the following steps: step 1, alternately identifying a part surface for contacting particle material in the mechanical part; step 2, automatically identifying that the part surface is a regularly curved surface or an irregularly curved surface; step 3, automatically identifying the missing part of the regularly curved surface; step 4, dispersing the irregularly curved surface into combination of regularly curved surfaces; step 5, reading the parameter of the regularly curved surface; step 6, alternately adding the motion parameters and material characteristic parameters of the curved surface; step 7, storing boundary model data. By changing the CAD (Computer - Aided Design) model of the mechanical part, the performances of mechanical parts with different structures and sizes can be analyzed so as to optimize the structures and sizes of the mechanical parts, thus solving the technical problem on the optimum design of the mechanical parts and bringing about remarkable technical effects.

The invention provides a detection method for cathode protection of a directionally drilled and crossed pipeline. According to the detection method, a numerical model of a metro stray current interference and cathode protection system is established by virtue of a boundary element method, the influences of the potential and the electric current density of a magnesium positive electrode, the value of stray current and the parallel length of a metro on a crossed-section cathode protection system are simulated, and thus a preliminary scheme for improving the directionally drilled crossed-section cathode protection system can be correspondingly proposed, so that the cathode protection system of the directionally drilled and crossed pipeline is improved, a cathode protection rule is met, and the safety operation of the pipeline is effectively guaranteed.

The invention discloses a heart electrical function imaging method based on beating heart model. The method comprises following steps: obtaining the position displacement change of heart based on double-ventricle electricity-coupled heart model; respectively constructing transfer matrixes TBH between epicardium and body surface potential of beating heart at different moments by adopting boundary element method; obtaining the body surface potential distribution PhiB of the body at different moments, calculating the potential distribution of the epicardium, and achieving heart electrical function imaging; and calculating the potential distribution of the epicardium by adopting normal TiKhonov regularization method. The heart electrical function imaging method based on beating heart model can effectively suppress the geometrical error caused by static heart model to obtain more accurate potential distribution imaging of the epicardium and accurately detect the electrical movement information of the heart, thus providing meaningful clinical information for the prevention and the treatment of heart diseases.

The invention discloses a method of acoustics simulated analysis and optimization for a cabin of a passenger plane. The method comprises the following steps that the cabin of the passenger plane is used as a prototype, a free meshing method is adopted based on HYPERMESH software, a cabin structure grid model containing seats is established, the cabin structure grid model is led into ANSYS in a *.cdb format, a Block Lanczos method is used for carrying out vibration mode analysis, a mode superposition method is used for carrying out harmonic response analysis, the vibration frequency response features of the cabin structure are obtained, a vibration frequency response feature destination file is led into SYSNOISE as an boundary incentives condition in a *.fre format which is capable of being recognized by the SYSNOISE, a direct boundary element method is used for finally obtaining sound pressure frequency response characteristics in the cabin, the cabin structure parameters are selected as design variables, and a lowest sound pressure order in the cabin is used as a design goal to carry out sound field optimization of civil aircraft cabins. According to the method of the acoustics simulated analysis and optimization for the cabin of the passenger plane, not only is the advantage that a finite element method is prone to obtaining vibration performance used, but also the advantage that the boundary element method obtains acoustic properties fast is brought in to full play, and therefore calculation speed is accelerated.

An embodiment of a method for solving the inverse problem of electrophysiology and determining a voltage distribution on a surface of a tissue may comprise receiving a plurality of voltages collected by a plurality of electrodes adjacent to the surface, discretizing the problem using a Finite Element Method (FEM) or a Boundary Element Method (BEM), introducing one or more regularization terms to an error minimization formulation, and solving, by a processor, the voltage distribution according to the plurality of voltages and according to the regularization terms. The regularization terms may comprise one or more of a Laplacian smoothness operator, a Tikhonov regularization matrix, a confidence matrix, and a linear operator that interpolates the plurality of electrode voltages to the tissue voltage distribution.

The invention puts forward a calculation method for electric aircraft propeller noise. The method comprises the following steps that: according to the structure parameter of an electric aircraft propeller, establishing a three-dimensional geometric model of the propeller; adopting a finite element method to carry out mesh generation on the flow field area of the three-dimensional geometric model of the propeller to obtain a propeller flow field subjected to the mesh generation; adopting a large eddy simulation calculation model to carry out unsteady pressure pulsation solving on the circulation area of the propeller flow field subjected to the mesh generation to obtain the transient pressure distribution of a paddle surface; and adopting an acoustic boundary element method to carry out acoustic field simulation on an acoustic mesh model to obtain the radiation noise distribution of the propeller. The method comprehensively considers each influence factor of noise, and therefore, a calculation result is accurate and reliable. The method can be used for aerodynamic noise frequency domain analysis and the like, and a theoretical basis and technical guidance are provided for effectively lowering the propeller noise.

The present invention discloses a design method of a biplane magnetic resonance imaging system gradient coil. The method comprises the steps of: performing three-dimensional continuous triangular meshdivision for a gradient coil area, according to a boundary element method, calculating a coil inductance matrix generated by the gradient coil area mesh node for a target field point, calculating thecurrent and the direction of the gradient coil plane through a coil target gradient value, an inductance constraint condition and a Tikhonov Regularization, and finally employing a stream function method to obtain actual winding distribution of the gradient coil. The design method of a biplane magnetic resonance imaging system gradient coil solves the problem that the coil inductance is large inthe gradient coil.

The invention discloses a method for predicting the acoustic radiation rule value of the noise of a wind turbine. The method comprises the steps of establishing a wind turbine model, defining flow field grids, calculating a flow field based on large eddy simulation and calculating sound field distribution based on the indirect boundary element method. The method is used for predicting the acoustic radiation rule value of the noise of the wind turbine by means of flow field calculation data combined with the boundary element method, with the assistance of software, the calculating processes can be simplified greatly, the prediction process is made simple, the calculating result is accurate, the calculated amount is small, speed is high, and the method has great application value in engineering.

The invention discloses a fractal dimension-based ultrahigh voltage DC transmission line boundary element method. When a DC line fails, after a protective element is started, a line-mode voltage is calculated by utilizing a phase-mode transformation theory according to DC voltages of two electrodes at a protection arrangement position; and a discrete line-mode voltage signal with the sampling sequence length of 200 points is selected, and fractals are measured by adopting a box dimension method to calculate a fractal dimension D for distinguishing an internal failure from an external failure. In the method, sampling frequency is 100 KHz, a time window is 2 ms, a required data length is relatively shorter and the influence of a control system is avoided. Various failures in the full-length range of the line can be accurately identified by the method. The method ensures relatively higher resistance to transition resistance, and is not influenced by interference and highly practical.

The invention discloses a method for calculating a complex structure radiation sound field in a marine acoustic channel, and belongs to the technical field of acoustic numerical calculation. The limitation that a traditional boundary element method is only suitable for free field sound field calculation is broken through, and a sound field Green function in an ocean sound channel is established. Ahierarchical matrix compression technology is adopted to divide a radiation impedance matrix into a series of hierarchical matrix blocks with different sizes, and an iteration method is further utilized to solve a matrix equation. Compared with the prior art, the method has the effects and benefits that the acoustic calculation function of the traditional boundary element method is expanded frominfinite uniform media to the bounded space of the ocean channel, and the influence of sea surface, seabed boundary and sound velocity gradient distribution can be considered. And on the other hand, the radiation impedance matrix is subjected to hierarchical compression, the consumption of a computer memory is greatly reduced by utilizing the low-rank characteristic approximate decomposition of the matrix block, the influence of the diversity of a sound field Green function under the complex marine channel condition is avoided, and the algorithm adaptability is good.

The invention provides a three-dimensional frequency domain numerical method for predicting wave drift load of a multi-floating body structure. The method comprises the following steps: Reading the mesh file, using the mesh information to carry on the ship hydrostatic calculation; calculating The influence coefficient matrix of simple Green's function Calculating The influence coefficient matrix of complex frequency domain Green's function. Taking The Taylor expansion boundary element method solve the unit radiation velocity potential, diffraction velocity potential and their spatial derivatives. solving Hydrodynamic Coefficients of Multiple Floating Body Structures; solving multi-floating body motion equation; solving The wave forces and wave drift loads of each unit for the whole multi-floating structure. According to the response RAO of floating body motion, anyalzing and calulating the floating body motion spectrum in irregular waves. The method of the invention can accurately predict hydrodynamic coefficients, motion RAO, wave forces, wave drift loads in a six-degree-of-freedom direction of each unit of a multi-floating body structure and results of floating body motion spectrum analysis.