17 results about "System matrix" patented technology

The invention discloses a meshless Galerkin-Newmark method for calculating a transient wave propagation problem. The meshless Galerkin-Newmark method comprises the following steps: dispersing a transient wave propagation problem domain into nodes; selecting an interpolation primary function and a weight function; constructing a node interpolation primary function and a global interpolation format by adopting a moving least square method based on the selected function; based on a global interpolation format, combining a partial differential control equation and a Galerkin weighted residual value method to obtain a transient wave propagation problem system matrix equation; performing time domain discretization through a Newmark time integration method to obtain a discrete time equation; solving the discrete time equation to obtain a numerical calculation result; and analyzing a result and comparing the result with a common method to finish solving and analyzing a transient wave propagation problem. The meshless Galerkin-Newmark method for calculating the transient wave propagation problem has a monotonous consistent convergence characteristic in the numerical calculation of the transient wave propagation problem, and the calculation precision can be continuously improved along with the reduction of the time integral step length.

In order to overcome the problem that the current technology is difficult to estimate and continuously correct the bridge twin model by obtaining a series of test and test data, the application provides a bridge twin dynamic model Fourier modeling method based on test data, which is only related to the parameters of the bridge according to the system matrix related to all nodes of the bridge and the observation coefficient matrix related to all nodes, and the first continuous test process of the bridge does not change greatly, and the first comprehensive detection of the bridge twin dynamic mathematical model and the subsequent each time of the bridge twin dynamic mathematical model comprehensive correction process is relatively short, according to the characteristics of the fast and slow change matrix, the slow change matrix is set as a constant matrix in the first continuous test, and the system matrix related to all nodes of the bridge and the observation coefficient matrix related to all nodes in the bridge twin model are established through a series of effective tests and optimal indexes, and the bridge twin model is continuously corrected in the whole life cycle of the bridge, so that the technical problem of estimating and improving the bridge vibration model by obtaining a series of test and test data is solved.

The application discloses an enhanced mobile least square meshless-Newmark integral method for reducing total dispersion error of transient wave propagation, and belongs to the technical field of numerical analysis and total dispersion error prediction of transient wave propagation, and comprises the following contents: a wave propagation problem domain is discretized into a series of nodes; a standard mobile least square interpolation base function of each node is derived; a local numerical approximation of an enhanced least square algorithm is completed; a global interpolation format of a general scalar field based on the enhanced least square algorithm is constructed; a system matrix equation of the dispersion analysis of the transient wave propagation problem is obtained by adopting a Galerkin weighted residual method and a Newmark time integral method; and based on a given node distribution, the total dispersion error of different calculation methods along different wave propagation directions under different time integral step lengths is calculated. The application adopts the above method, reduces the total dispersion error caused by the coupling of spatial dispersion and time dispersion, and improves the solving precision.

This invention discloses a method and system for extracting S-parameters of microwave passive devices, comprising: geometrically modeling the microwave passive device and then meshing it to obtain a processed device model; discretizing the processed device model according to basis functions, and performing mode function expansion on the ports of the processed device model to establish a transfinite element matrix equation; performing partial LU decomposition of the system matrix in the transfinite element matrix equation using the multi-wavefront method to obtain the Schur complement matrix of the system matrix and the decomposed system matrix; obtaining the dense S-parameter matrix equation for the microwave passive device based on the Schur complement matrix of the system matrix and the decomposed system matrix; and solving the dense S-parameter matrix equation to obtain the S-parameters of the microwave passive device. This invention effectively reduces the memory usage of matrix calculations and reduces computation time.

The invention discloses an enhanced moving least square algorithm for reducing frequency dispersion errors of wave propagation analysis, which comprises the following steps of: dispersing a wave propagation problem domain into nodes, and constructing an interpolation primary function of the nodes based on a standard moving least square algorithm; constructing local strengthening numerical approximation containing a local strengthening primary function and a coefficient at the node; constructing a global interpolation format of a general scalar field based on an enhanced moving least square algorithm on the premise of meeting unit decomposition characteristics; and obtaining a system matrix equation for frequency dispersion analysis of the wave propagation problem by using the constructed enhanced global interpolation format, combining with a partial differential control equation of the wave propagation problem and adopting a Galerkin weighted residual value method, and further calculating to obtain a frequency dispersion error of the wave propagation problem. According to the enhanced moving least square algorithm for reducing the frequency dispersion error of the wave propagation analysis, the frequency dispersion error can be obviously reduced during frequency dispersion analysis, so that a more accurate numerical result can be obtained during wave propagation problem analysis.

To overcome the current technical problems of difficulty in analyzing the causes of bridge anomalies and the inability to actively prevent bridge resonance, this invention provides a Fourier method for anomaly reproduction and resonance prevention based on a bridge twin dynamic model. This method relies on the fact that the system matrix related to all bridge nodes and the observation coefficient matrix related to nodes are only related to the bridge parameters and do not change significantly during a single continuous bridge test. The reproduction of bridge anomalies or the simulation of bridge resonance and abnormal loading tests are relatively short. Based on the characteristics of slowly changing matrices, a singular perturbation method is used to set the slowly changing matrix as a constant matrix in a single continuous test. Fourier series approximation is used to approximate the fast-changing variable over time, obtaining the ambiguous excitation input when bridge anomalies occur. The system's reproduction of anomalies is verified through equivalent bridge simulation; thus, the artificial excitation input for simulating bridge resonance or anomalies is obtained, solving the technical problems of difficulty in analyzing the causes of bridge anomalies and the inability to actively prevent bridge resonance.

The application discloses a smooth finite element-Newmark calculation method for underwater target transient acoustic scattering, and belongs to the technical field of underwater transient acoustic scattering numerical simulation. First, a calculation domain of an underwater transient acoustic scattering field is discretized into a standard quadrilateral element grid, and an acoustic pressure field interpolation format is constructed. The quadrilateral element is divided into multiple smooth domains, a smooth acoustic pressure gradient field is obtained through acoustic generalized gradient smoothing technology, and a smooth acoustic pressure gradient matrix is obtained through Gaussian integration. A system matrix equation is constructed in combination with a transient acoustic scattering control equation and a Galerkin weighted residual value method. A parameter-optimized Newmark time integration method is used to complete time domain discretization and recursive solving, and numerical results of the transient acoustic scattering field are obtained. The application softens the system stiffness matrix through gradient smoothing technology, reduces spatial discretization error, eliminates time domain false numerical damping, and has higher precision than the standard finite element method under the same grid, thereby providing an efficient and reliable scheme for underwater transient acoustic scattering engineering calculation.

The invention relates to a coil topology design method and device based on magnetic field reverse reconstruction, computer equipment, a computer readable storage medium and a computer program product, relates to the technical field of electromagnetic engineering and wireless power transmission, and can improve the robustness of coil design. The method comprises the following steps: acquiring a target magnetic field distribution vector of a coil in a target area, and determining a spatial weighting matrix according to spatial position distribution; constructing a primary function dictionary of the stream function; performing weighting processing on the physical mapping matrix and the target magnetic field distribution vector by using a space weighting matrix to obtain a weighting system matrix and a weighting magnetic field vector; performing truncation singular value decomposition on the weighted system matrix to obtain a truncation result, and determining a target weight coefficient of the primary function dictionary based on the truncation result and the weighted magnetic field vector; and reconstructing stream function distribution on the extended computational domain based on the primary function dictionary and the target weight coefficient, and determining a geometric topology path of the coil according to the stream function distribution.

This invention discloses a smoothed finite element adjustable damping implicit integral algorithm for underwater transient acoustic scattering, belonging to the field of underwater transient acoustic scattering numerical simulation technology. First, the computational domain of the underwater transient acoustic scattering field is discretized into a standard quadrilateral element mesh to construct an interpolation scheme for the sound pressure field. Then, each quadrilateral element is divided into multiple smooth domains, and the smoothed sound pressure gradient matrix is ​​obtained through acoustic generalized gradient smoothing technology. Combining differential control equations, the virtual displacement principle, and the Galerkin weighted residual method, the system matrix equation is constructed. An adjustable damping implicit time integral algorithm is used to complete the time-domain discretization, and the numerical results of the transient acoustic scattering field in the entire time domain are obtained through recursive solution. This invention can soften the "overly stiff" stiffness matrix to reduce spatial discretization errors, suppress high-frequency errors through adjustable numerical damping matching, and achieve coordinated control of spatiotemporal errors. Under the same mesh, its accuracy is superior to the standard finite element method, providing an efficient and reliable solution for underwater transient acoustic scattering engineering simulation.

The invention discloses an enhanced meshless Galerkin algorithm for reducing the frequency dispersion error of wave propagation analysis, which comprises the following steps: dispersing a wave propagation problem domain into nodes, selecting an interpolation primary function and a weight function, constructing an approximate interpolation function based on a standard meshless Galerkin algorithm, determining an undetermined coefficient through least square fitting, and determining the frequency dispersion error of the wave propagation analysis. Further establishing a physical field global interpolation format; constructing local reinforcement numerical approximation containing a local reinforcement interpolation primary function and a coefficient at the node; constructing a global interpolation format based on an enhanced meshless Galerkin algorithm on the basis of local enhanced numerical approximation under the condition of meeting unit decomposition characteristics; and an obtained global interpolation format is combined with a wave propagation problem partial differential control equation and a Galerkin weighted residual value method to obtain a system matrix equation which is used for frequency dispersion error analysis of the wave propagation problem. By adopting the enhanced meshless Galerkin algorithm for reducing the frequency dispersion error of wave propagation analysis, the frequency dispersion error can be remarkably reduced, and a more accurate numerical calculation result can be obtained.

The invention discloses a load identification method and system based on singular value adaptive improved regularization, and relates to the technical field of aircraft dynamic load identification. The method comprises the steps that singular value decomposition is carried out on a pre-constructed system matrix, adjustment indexes corresponding to all orders are calculated according to singular value distribution characteristics, and the adjustment indexes are used for applying differential suppression intensity to singular values of different sizes; setting a range of regularization parameters, and screening to obtain an optimal regularization parameter by adopting a minimization criterion of a generalized cross validation GCV function; and carrying out load identification in combination with the adjustment index and the regularization parameter, constructing an improved regularization objective function, and solving the improved regularization objective function to obtain an optimal solution of load identification. According to the characteristic that singular values of different sizes have different influences on the stability of an identification result, differential suppression is carried out on the different singular values, the robustness of the model to small singular value disturbance and the fidelity of the model to main energy components are improved, and therefore the accuracy of ill-conditioned matrix inversion is improved.

A magnetic particle imaging (MPI) measurement method includes generating a multi-dimensional image-domain system matrix A using an MPI-sequence with a field free line, using a multi-dimensional sinogram-based system matrixASinogram(t,r,z)∈ℝ[T,Nr,Nz],comprising the following steps:for each time point tc, c∈[1, T]:get a time slice matrix Ac=ASinogram(t=tc, r, z)∈[N<sub2>r< / sub2>,N<sub2>z< / sub2>],replicate the time slice matrix Ac Nr−1 times and copying these replications along a newly added 2nd offset-dimension, resulting in a time volume matrixAc′∈ℝ[Nr,Nr,Nz],rotate the time volume matrixAc′ by the FFL θc=θ(t=tc) at time point t=tc in its 1st and 2nd offset-dimensions, resulting in a rotated matrixAcθ cconcatenate the rotated matricesAcθ c of all time points along a time-dimension and vectorize the spatial dimensions (x, y, z), resulting in a constructed system matrix cSM∈[T,(N<sub2>r< / sub2>×N<sub2>r< / sub2>×N<sub2>z< / sub2>)], andperform a Fourier transformation on the constructed system matrix cSM on its time-dimension resulting in the multi-dimensional image-domain system matrix A.

This invention relates to the field of geophysical exploration technology, specifically to a high-precision three-dimensional forward modeling method for airborne electromagnetic spectral elements considering induced polarization effects. Based on the Cole-Cole model, a complex conductivity expression considering induced polarization effects is established, and the frequency domain Helmholtz equation is introduced to construct the corresponding governing equations. A regular hexahedral mesh is generated, and reference domain vector basis functions are constructed using the Gauss-Lobatto-Legendre orthogonal polynomial method according to the spectral element method. The mapping relationship between these functions and physical mesh elements is established. The Galerkin weighted residual method is applied to discretize the governing equations into element system matrices, which are then assembled to form the overall system matrix and the corresponding linear equation set. A direct solver is used to obtain the frequency domain three-dimensional electromagnetic response, and the time domain three-dimensional forward modeling result of the computational region is obtained through Hankel transformation. This invention achieves rapid and high-precision three-dimensional forward modeling simulation of complex geological models containing induced polarization effects.

The application discloses a smooth finite element-Bathe calculation method for underwater target transient acoustic scattering, and belongs to the technical field of underwater transient acoustic scattering numerical simulation. Firstly, a sound scattering field calculation domain is discretized into a quadrilateral element grid, and an acoustic pressure field interpolation format is established; then, an element smooth domain is divided, a smooth acoustic pressure gradient matrix is obtained through acoustic generalized gradient smoothing technology, and a system matrix equation is constructed in combination with a transient acoustic scattering control equation and a Galerkin weighted residual value method; time domain discretization is completed through the Bathe time integration method, and iterative solution is carried out, so that full-time domain numerical results of the transient acoustic scattering field are obtained. Through the gradient smoothing technology, the spatial discretization error is reduced, error cooperative suppression is realized in combination with the frequency self-adaptive numerical damping of the Bathe integration method, the precision is higher and the stability is better than those of the standard finite element method under the same grid, and an efficient and reliable scheme is provided for underwater transient acoustic scattering engineering solution.

The invention discloses an enhanced moving least square meshless method for calculating a steady-state sound propagation problem, and relates to the technical field of numerical simulation calculation and numerical forecasting of the steady-state sound propagation problem, and the method comprises the steps: S1, constructing an interpolation function of a steady-state sound field; s2, constructing a local enhanced interpolation primary function; s3, constructing a global interpolation format; s4, constructing a numerical calculation model for discretization of the steady-state sound propagation problem; s5, constructing a discrete system matrix equation; s6, sound pressure solving is carried out; s7, result verification and analysis; according to the enhanced moving least square meshless method for calculating the steady-state sound propagation problem, the problem that high-frequency errors are large in existing steady-state sound propagation calculation is solved.

The application discloses a modal identification method based on an unsupervised optimization covariance stochastic subspace method, and comprises the following steps: arranging vibration sensors on a to-be-measured structure with noise interference or weak excitation modes, and acquiring structural dynamic response data; calculating a covariance matrix and constructing a toply matrix; calculating an extended observable matrix and a controllable matrix based on the weighted toply matrix; defining a toply matrix row block number and a model order parameter range, and iteratively calculating a parameter optimization index; calculating a cumulative contribution rate based on a singular entropy increment of the toply matrix and determining a critical model order; calculating a cumulative parameter optimization index in an interval from a minimum model order to the critical model order under different toply matrix row block numbers, and determining an optimal parameter combination through an average minimum value; substituting the optimal parameter combination into a covariance stochastic subspace algorithm to identify a system matrix and calculate structural modal parameters; and automatically identifying each order physical mode from candidate modes by using a DBSCAN clustering method. The application further discloses a system and an electronic device.

The invention relates to a method for calculating a multi-dimensional image domain system matrix for MPI measurement by using a system matrix based on a multi-dimensional sinogram. The invention relates to a method for generating a multi-dimensional image domain system matrix using a multi-dimensional sinogram-based system matrix with MPI sequences having no field lines, comprising the steps of: for each point in time: obtaining a time slice matrix, replicating the matrix and copying these replications along a newly added second offset dimension to obtain a time volume matrix; and at a time point, rotating the matrix at a first offset dimension and a second offset dimension by an FFL angle to obtain a rotation matrix, cascading the rotation matrixes of all the time points along the time dimension, vectorizing the space dimension to obtain a constructed system matrix, and performing Fourier transform on the constructed system matrix at the time dimension to obtain a multi-dimensional image domain system matrix. According to the method, the total calibration time can be shortened.