5 results about "Dispersion relation" patented technology

The invention discloses a seismic wave field simulation method and system in an attenuation medium. A new constant Q viscous sound wave equation is constructed to accurately meet the dispersion relation of the Kjartansson constant Q theory, and an amplitude attenuation item and a phase dispersion item are subjected to explicit separation, so that complete decoupling of attenuation and dispersion can be realized while the theoretically accurate constant Q dispersion relation is kept, and the frequency dispersion accuracy is improved. And solving a constant Q viscous acoustic wave equation through a generalized pseudo-spectral numerical simulation method based on space Fourier transform to obtain a seismic wave field with spatio-temporal variation, so that the precision of viscous acoustic wave simulation is remarkably improved.

The application discloses a method for calculating lattice thermal conductivity of rare earth oxide based on first principle. The method comprises the following steps: establishing a crystal structure model of the rare earth oxide, and constructing a supercell model after structure optimization; calculating second-order interatomic force constants by using a first principle method to obtain a phonon dispersion relation, and calculating third-order interatomic force constants to obtain a phonon scattering rate; solving the lattice thermal conductivity by using a Wigner transport equation, wherein the lattice thermal conductivity comprises a particle contribution described by a diagonal item of a phonon spectral function and a wave contribution described by a non-diagonal item, and the two are added to obtain a thermal conductivity contribution of each phonon mode; and integrating and summing all phonon modes in a Brillouin zone to output a frequency, temperature and direction dependence of the total lattice thermal conductivity. The application can accurately predict the lattice thermal conductivity and anisotropy of the rare earth oxide in a wide temperature range without an empirical parameter.

The embodiment of the invention provides a high-precision seismic elastic wave field forward modeling method, device and equipment and a storage medium, and the method comprises the steps: carrying out the discretization of a wave equation in an elastic medium through the combined application of an improved time high-order implicit staggered grid difference method, and obtaining two types of time-space domain frequency dispersion relationships related to a P wave and an S wave based on the plane wave arrangement and simplification; solving the two types of time-space domain dispersion relations of the P wave and the S wave by combining a least square method and a Taylor series expansion method to obtain high-order difference coefficients corresponding to the P wave and the S wave; based on a wave field separation technology, a P wave field component is calculated by using a high-order difference coefficient corresponding to a P wave, an S wave field component is calculated by using a high-order difference coefficient corresponding to an S wave, and the components are superposed to obtain a high-precision full-elastic wave field. According to the technical scheme, under the same parameter condition, better simulation precision can be generated, so that an effective wave field continuation scheme is provided for subsequent elastic wave migration imaging and waveform inversion.

The invention relates to the field of testing of rock and soil mechanics and granular material mechanics, and provides a method and a system for obtaining structure anisotropy parameters of a discrete material, and the method comprises the following steps: S1, establishing a micro-form constitutive model for describing the particle motion state of the discrete material; s2, obtaining a frequency dispersion relation between spin longitudinal waves and spin transverse waves; s3, establishing a relation model between the cut-off frequency and the anisotropic parameters of the discrete material structure; and S4, performing inversion to obtain the structure anisotropy parameters of the discrete material. According to the method, the characteristics that the spin wave cut-off frequency is non-zero and can be stably measured are fully utilized, the defect that a traditional wave velocity inversion method based on displacement waves is greatly influenced by the frequency dispersion effect and test conditions is effectively overcome, and the method has the advantages of being clear in theoretical basis, high in measurement stability, high in inversion precision, high in application and popularization performance and the like; the method can be widely applied to structural diagnosis of granular materials, design optimization of engineering materials and anisotropic recognition research of complex geological media.

This invention relates to the field of physical acoustics, and in particular to a method and system for calculating the dispersion relation of Schulte waves on a single-phase medium nonlinear metasurface. The method includes the following steps: obtaining expressions for the displacement and stress components of the single-phase medium under the action of a Schulte wave; obtaining expressions for the fluid displacement component and the fluid normal stress, as well as expressions for the relative motion of the resonator; based on all expressions, applying stress and displacement continuity boundary conditions at the interface between the single-phase medium and the fluid layer to obtain the characteristic equation of the dispersion characteristics of the coupled system, solving it, and finally obtaining the dispersion curve of the coupled system. This invention improves the computational efficiency and prediction accuracy of wave propagation at the interface of a single-phase medium nonlinear metasurface by providing an explicit dispersion relation for Schulte waves on a single-phase medium nonlinear metasurface, which is beneficial for reducing the computational cost and design cycle of acoustic metasurface design, vibration suppression, and waveguide control.