39 results about "Spectral element method" patented technology

The invention discloses an unconditional stability and conditional stability mixed time domain spectral element electromagnetic analyzing method. In a traditional time domain spectral element method, for complex models, especially under the condition of containing multiscale problems, the sizes of meshes obtained through hexahedral subdivision are not uniform. In the subsequent time iteration, in order to ensure that an algorithm is stable and not diverging, the time step is set according to the size of the minimum subdivision mesh, and therefore the whole solution process wastes a large amount of time. The invention provides the self-adapting unconditional stability and conditional stability mixed time domain spectral element method. Small meshes and large meshes are automatically found out through the self-adapting method, an ordinary central difference format is used for the large mesh area, and a Newmark-beta difference format is used for the small mesh area, so that the unconditionally stable iteration format is obtained, the whole time step can be very large, and the solution time is greatly shortened.

The invention discloses a multi-grid Chebyshev parallel spectral element method. The method includes the steps that a, a calculation area is divided into large and regular units; b, main grids and auxiliary grids are defined in the units, and the main grids are Chebyshev collocation points; c, Wave fields in the units are subjected to Chebyshev truncation expansion by the utilization of the main grids, and medium parameters and external forces in the units are subjected to truncation expansion by the utilization of the auxiliary grids; d, wave field, medium parameter and external force truncation expansion formulas are substituted into a wave equation to obtain unit mass matrixes, unit stiffness matrixes and unit external force vectors; e, on the basis of the unit mass matrixes, the unit stiffness matrixes and the unit external force vectors, an elastic wave expansion is solved on the main grids.

The invention discloses an electric-heat integrated analysis method for a MESFET under the action of high-power electromagnetic pulses. The method comprises the steps that a drifting-diffusing equation set is solved by taking the electronic quasi Fermi potential, the hole quasi Fermi potential and the electric potential as variables and adopting a time domain spectral-element method to solve the instaneous quasi Fermi potential and electric potential of the metal-semiconductor field effect tube (MESFET) under the action of the high-power pulses, and then the electric field intensity and the current density at the moment are obtained; temperature distribution of all positions at the moment can be obtained under the action of a joule heat source by considering the influences of ambient environment temperature and heat convection; the carrier mobility and the generation-recombination rate are updated according to temperature changes, electric field distribution is recalculated, the steps are repeatedly conducted until the drifting-diffusing equation set meets the convergence precision, and electric field distribution and heat distribution at the moment are to-be-solved electric-heat distribution inside the MESFET at the moment. The method is achieved on the basis of a MESFET physical model, and the distribution conditions, changing along with time, of an electric field and the temperature in a device under the action of the high-power electromagnetic pulses can be clearly obtained.

The invention discloses a Lengendre spectral element method elastic wave propagation parallel simulation method based on an element-by-element technology, which is based on a Lengendre-expanding spectral element method and adopts the element-by-element technology to realize the method for simulating wave propagation in parallel in such a way that a main node controls a plurality of independent computing nodes. The method comprises the following steps: (1) firstly, rewriting an elastic wave propagation equation by adopting the Lengendre spectral element method; carrying out the task allocation of each computing node according to an equilibrium principle after the space of the whole computing area is dispersed; computing an element mass matrix and an element stiffness matrix which are contained by the respective task of each computing node by each computing node, and storing in the storage of each computing node; and (2) then, computing the overall lattice vector of the whole iteration time slot at the main node by adopting a time domain iteration method, and simultaneously, converting the overall matrix and the vector product of the equally distributed task by each parallel computing node by adopting the element-by-element technology into an element matrix and a vector product. The invention also discloses how to apply the element-by-element technology to the Lengendre spectral element method and lays foundation for realizing parallel methods.

The invention discloses a spectral modeling method for main ice of The Yellow River based on automatic coder and a multilayer perceptor network, wherein the method is used for settling a technical problem of low self-adaptability in an existing modeling method. The method is characterized in that many factors such as the absorption coefficient and the scattering coefficient of a water molecule, the absorption coefficient and the scattering coefficient of a slit particle, incident angle of light and upward scattering angle of water layer are comprehensively considered; and utilizing a neural network structure which is formed through connecting the automatic coder with a multilayer perceptor, studying by means of training data, and finally obtaining the spectral model of the main ice of The Yellow River. The automatic coder has characteristics of effective redundancy information elimination and high robustness to the noise, and therefore obtaining of robustness parameter estimation result is facilitated. According to the spectral model for the main ice of The Yellow River, reasons of the main ice are considered; the factors such as water body, split and illumination are comprehensively considered; and the automatic coder and the multilayer perceptor network are used in the model parameter estimating method; particular model parameters can be automatically acquired according to the data; and high expandability and high self-adaptability are realized.

The invention discloses a manifold mapping algorithm based on a high-and-low-order time domain spectral element method. The algorithm comprises the steps that firstly, an electromagnetic structure geometric model including a plurality of physical variables is established, and variable optimization simulation is quickly conducted through a time domain spectral element method with a first-order vector basis function till a simulated frequency response meets a target frequency response; secondly, according to the optimized variables, simulation is conducted through a time domain spectral elementmethod including a second-order basis function, whether the simulated frequency response meets the target frequency response or not is judged, and if yes, optimization simulation is finished; thirdly,if not, a correction frequency response model including the two simulation frequency responses is constructed, fast variable optimization simulation is carried out again through the time domain spectral element method including the first-order basis function till the correction frequency response meets the target frequency response; the second step is repeated after optimization is finished. Themethod has the advantages of being high in optimization speed, high in calculation precision and the like, and an important value reference can be provided for simulation design of a microwave device.

The invention provides a design method of an energy-saving lighting source spectrum and aims at solving the problem of energy waste due to that an invalid spectrum of an existing lighting source is absorbed by an object in the prior art. The design method comprises the following steps: (1) obtaining spectral reflection properties; (2) establishing an optimization goal and a constraint condition; (3) solving a genetic algorithm; and (4) further obtaining a group of spectral data lowest in energy consumption according to a chromosome lowest in fitness obtained in the previous step, wherein the data is the energy-saving lighting source spectrum of an object to be lighted. In the design method, firstly, the spectral reflection properties of the surface of the object to be lighted are obtained, and secondly, the light source spectrum is optimized by use of the genetic algorithm under the condition of ensuring that the chromatic aberration between the designed light source and a white light source is smaller than values within a human eye perceptible range; as a result, the portion, absorbed by the object, of the spectrum is reduced, the utilization rate of the spectrum and the energy utilization rate are increased, and the purposes of saving energy and lighting are achieved. The design method of the energy-saving lighting source spectrum is applicable to lighting such as display lighting and furniture lighting in buildings.

The invention discloses a rapid numerical simulation method for element-by-element parallel strong ground motion. The method comprises the following steps: 1) transforming a hexahedron unit into a standard cube unit through isoparametric transformation; 2) averagely distributing hexahedron units obtained by spatial discretization to a plurality of calculation cores for parallel calculation; 3) adopting high-order Lagrange interpolation on each unit to obtain an interpolation polynomial, and directly performing approximation on the spatial differential operator by utilizing interpolation multiple terms to form a unit stiffness matrix; 4) performing product operation of the element stiffness matrix and the solution vector on the calculation core; and 5) realizing communication between the process pairs according to a product operation result in a cache communication mode. In the theoretical framework of the spectral element method, the element-by-element parallel algorithm for directly solving the seismic wave motion equation is developed, the calculation amount of seismic wave numerical simulation is effectively reduced by improving the spatial discrete format of the traditional spectral element method and adopting a more efficient parallel calculation communication mode, the seismic wave parallel calculation efficiency is improved, and high-efficiency and high-precision strong ground movement becomes reality.

The invention discloses an unconditional stability and conditional stability mixed time domain spectral element electromagnetic analyzing method. In a traditional time domain spectral element method, for complex models, especially under the condition of containing multiscale problems, the sizes of meshes obtained through hexahedral subdivision are not uniform. In the subsequent time iteration, in order to ensure that an algorithm is stable and not diverging, the time step is set according to the size of the minimum subdivision mesh, and therefore the whole solution process wastes a large amount of time. The invention provides the self-adapting unconditional stability and conditional stability mixed time domain spectral element method. Small meshes and large meshes are automatically found out through the self-adapting method, an ordinary central difference format is used for the large mesh area, and a Newmark-beta difference format is used for the small mesh area, so that the unconditionally stable iteration format is obtained, the whole time step can be very large, and the solution time is greatly shortened.

The invention discloses a multi-grid Chebyshev parallel spectrum element method. The method includes: a. Divide the calculation area into large and regular cells; b. Define the main grid and the auxiliary grid in the unit, the main grid is the Chebyshev configuration point; c. Use the main grid to divide the unit The wave field is truncated by Chebyshev, and the medium parameters and external forces in the element are truncated and expanded by using the auxiliary grid; d. Substitute the truncated expansions of the wave field, medium parameters, and external forces into the wave equation to obtain the element mass matrix and element stiffness matrix and the element external force vector; e. Based on the element mass matrix, element stiffness matrix and element external force vector of each element, the elastic wave equation is solved on the main grid.

The invention discloses a microwave gas discharge numerical simulation method of a waveguide device. The method establishes a fluid model of a microwave gas discharge in a waveguide structure, and performs accurate numerical simulations of electron density, electron fluid velocity and average electron energy in the process of gas breakdown. Through the analysis, the law of electric field intensity and electron density at different observation points with time can be obtained in the case of gas discharge in complex structure waveguide devices with different geometric shapes. Based on the time-domain spectral element method, the present invention can realize the modeling of waveguide devices with arbitrary complex structures; the generated mass matrix is ​​a block diagonal matrix, and the inverse matrix can be directly obtained, which greatly reduces the calculation time; at the same time, the method of numerical simulation can Avoid repeated experiments to obtain the internal electric field distribution and electron density of waveguide devices, obtain the breakdown threshold, shorten the design cycle, and save design costs. It is very suitable for effective simulation design and numerical simulation of complex waveguide devices with discontinuous structures .

The invention relates to a fluorescence-detecting and spectrum pre-processing method for lubricating oil metal X-rays. The fluorescence-detecting and spectrum pre-processing method comprises the following steps: primary X-ray excitation and control, lubricating oil metal X-ray fluorescence spectrum detection, environment gas regulation, and detected spectrum pre-processing. According to the fluorescence-detecting and spectrum pre-processing method, the optimal excitation voltage and current are determined according to the critical excitation energy of a detected metal component, so that scattering spectrum influences caused by characteristic spectrum of a target material are the smallest, and the characteristic peak type and the energy spectrum with the best strength can be obtained; the performances of the detected whole spectrum and the characteristic spectrum are changed by designing pulse shaping time, pulse width, pulse signal recording time, a quick threshold value, an energy spectrum correction coefficient and the like, so that the requirements of simultaneously recording a strong characteristic peak and a weak characteristic peak are met; the gas environment of a measuring light path is flexibly regulated according to the measuring requirements, so that the accurate measurement on light metal elements in a low-energy-spectrum area is realized; and by adopting background baseline self-adaptive correction based on multi-scale decomposition is adopted, so that the requirements of directly measuring lubricating oil metal of an aero-engine are met.