8 results about "Boundary integral equations" patented technology

The present application relates to the technical field of numerical calculation, in particular to a large-scale boundary element iteration initial value generation method based on boundary information neural network, comprising: constructing a basic data set of a small-scale example to train a pre-constructed deep neural network architecture; inputting known physical quantities of a to-be-solved domain into a physical information neural network based on boundary integral equation constraint obtained after training to predict small-scale unknown physical quantities; mapping the small-scale unknown physical quantities to actual calculation points corresponding to a large-scale fast boundary element method by using a boundary integral equation, and aligning degrees of freedom to generate a large-scale initial vector of degrees of freedom; and inputting the large-scale initial vector of degrees of freedom into a large-scale fast boundary element iteration solver to perform iteration as an initial value. Thus, the defects of the existing large-scale fast boundary element method in processing complex engineering problems, such as slow iteration convergence and large influence of initial value selection on calculation efficiency, are solved.

The present application belongs to the field of ship hydrodynamics and motion prediction, and in particular to a device and method for predicting the hydrodynamics and motion of a ship coupled with ice, which first derives a Green function that satisfies the boundary conditions of the ice layer and the free surface, as well as all other conditions except the surface condition of the ship, and through the Green function, the differential equation of the velocity potential is converted into a boundary integral equation on the surface of the ship only, which introduces an extended surface at the waterline of the ship body to eliminate the influence of irregular wave frequencies; an asymptotic solution formula of the Green function is analytically derived, thereby establishing an approximate and effective solution program for the coupled interaction of the ship / wave / ice layer, and numerically calculating the results of the added mass, damping coefficient and wave exciting force of the ship body; through the method, the interaction mechanism of the water wave / ship / ice layer under different parameter characteristics can be deeply understood, and theoretical support is provided for the hydrodynamic problems, motion prediction and rational design of polar ships.

The invention discloses a high-order grid parallel generation method based on GPU acceleration and fine projection, and the method comprises the steps: firstly inputting an original volume grid and a surface grid, and carrying out the order lifting processing, and obtaining a high-order volume grid and a high-order surface grid; secondly, calculating physical offsets of all nodes on the high-order surface grid relative to the high-order surface grid through projection by utilizing an AABB tree structure, and storing the offsets as displacement potential function values; then, on the basis of a boundary integral equation, physical offset vectors of all internal nodes in the volume mesh are calculated in parallel through a GPU; and finally, traversing all grid nodes, and updating all point coordinates according to the physical offset vectors of the internal nodes to obtain a generated high-order grid. According to the method, the calculation time of the boundary offset is greatly shortened, and the method has the advantages of high efficiency, high expandability and high precision and is suitable for high-precision CFD simulation pretreatment of industrial-grade complex shapes.

The invention relates to the technical field of electromagnetic full-wave inversion, in particular to a two-dimensional cross-layered efficient electromagnetic full-wave inversion method based on a spectral element boundary integral method.During forward modeling calculation, a scatterer crossing multiple horizontal layers is surrounded by a one-dimensional smooth boundary, and two-dimensional electromagnetic field distribution is solved by adopting a spectral element method in a region; accurately truncating an SEM solving domain on the boundary by using a boundary integral equation; for a transverse electric mode and a transverse magnetic mode, equivalent current / magnetic current is solved by using BIE, and a receiver scattering field is calculated in combination with a layered two-dimensional vector Green function; in the full-wave inversion, in order to reconstruct TE mode isotropic scatterer model parameters and TM mode anisotropic scatterer model parameters respectively, first-order derivatives of a mass matrix and a stiffness matrix relative to the corresponding parameters are calculated respectively, a sensitivity matrix is constructed, and an LM optimization algorithm is adopted to iteratively call an SEBI forward solver to complete inversion; multiple groups of numerical experiments verify the accuracy and high efficiency of the SEBI-LM algorithm in forward modeling and FWI.

This invention discloses a time-domain numerical method for calculating the hydrodynamic performance of ships in the field of marine hydrodynamics. The method includes: establishing a three-dimensional numerical model of the hull and free surface; decomposing the total velocity potential based on time-domain potential flow theory; constructing boundary integral equations; introducing a time-increasing monotonically increasing function to smooth the initial transient response; simultaneously iteratively solving the free surface evolution and the ship's six-degree-of-freedom motion equations; and achieving self-consistent coupling between flow field pressure and ship motion using a closed feedback loop. This method also supports nonlinear free surface boundary conditions, suppresses numerical dissipation through high-order extrapolation, and dynamically calculates the restoring force matrix based on surface element integrals, significantly improving the calculation accuracy and stability of ship motion response in confined waters. It is suitable for engineering prediction of complex conditions such as near-shore navigation, shallow water resonance, and shoreline reflection.

The invention relates to a seismic wave forward modeling method and device based on a viscoelastic medium and electronic equipment. The method comprises the following steps: acquiring viscoelastic medium parameters of a stratum to construct a viscoelastic wave fluctuation equation; acquiring a wave equation based on a viscoelastic wave wave equation, and constructing a second-order Green displacement tensor based on the viscoelastic medium density, the angular frequency and a Green function of a scalar wave equation; the method comprises the following steps: acquiring a first coefficient expression of a second-order green displacement tensor based on a geometric model of a viscoelastic medium, introducing a frequency-dependent complex velocity, constructing a green function based on the complex velocity, and acquiring a first solving subitem based on the green function and the first coefficient expression; based on Hooke's law and the first solving subitem, obtaining a second solving subitem; obtaining a frequency domain viscoelastic medium boundary integral equation on the basis of the first solving subitem and the second solving subitem; and performing discrete solution on the frequency domain viscoelastic medium boundary integral equation to obtain the displacement and stress of the seismic wave in the propagation process. And calculation errors can be reduced.

This invention relates to the field of capacitance calculation technology and discloses a fast algorithm for extracting parasitic capacitance in large-scale integrated circuits. This method combines the method of moments (MoM), a fast multipole algorithm for layered dielectrics, and overlapping region decomposition preprocessing techniques to construct a complete parasitic capacitance extraction solution. By directly introducing the Green's function for the layered dielectric, the numerical solution strictly satisfies the electric field transport conditions at the dielectric interface, and the electrostatic problem in the layered dielectric is transformed into boundary integral equations defined on the interconnect surface. Subsequently, the MoM is used to discretize these boundary integral equations, resulting in a large-scale dense system of linear algebraic equations. To improve solution efficiency, an efficient preprocessing strategy based on overlapping region decomposition is further designed, and combined with the matrix-free minimum residual iteration method and the layered fast multipole algorithm, achieving efficient solution with low computational and storage overhead.

The invention discloses a GIL basin-type insulator surface charge inversion algorithm based on a boundary integral equation and a least square method, and the algorithm comprises the steps: enabling an experiment platform to apply a stable DC voltage to a basin-type insulator in a cavity through a DC high-voltage console, and enabling a protection resistor to be connected in series in front of an insulating sleeve; the damage to direct-current power supply equipment caused by accidental surface flashover in an experiment process is prevented; the basin-type insulator sample is driven to rotate through the rotating platform, and dynamic measurement of the surface potential is completed in cooperation with the electrostatic probe; and the electrostatic potentiometer transmits potential data acquired in real time to the computer through the data acquisition card for subsequent processing. The method is suitable for online monitoring of the insulation state of the + / -800 kV direct current GIL, economic losses and safety risks of workers caused by faults are reduced, and meanwhile high-precision and high-robustness experiment and data support is provided for equipment optimization design and safe operation.