Numerical simulation in the frequency-space domain has inherent advantages, such as： it is possible to simulate wave propagation from multiple sources simultaneously; there are no cumulative errors; only the interest...Numerical simulation in the frequency-space domain has inherent advantages, such as： it is possible to simulate wave propagation from multiple sources simultaneously; there are no cumulative errors; only the interesting frequencies can be selected; and it is more suitable for wave propagation in viscoelastic media. The only obstacle to using the method is the requirement of huge computer storage. We extend the compressed format for storing the coefficient matrix. It can reduce the required computer storage dramatically. We get the optimal coefficients by least-squares method to suppress the numerical dispersion and adopt the perfectly matched layer （PML） boundary conditions to eliminate the artificial boundary reflections. Using larger grid intervals decreases computer storage requirements and provides high computational efficiency. Numerical experiments demonstrate that these means are economic and effective, providing a good basis for elastic wave imaging and inversion.展开更多
For engineering electromagnetism,one of a typical case is that a medium/object rotates possibly with a deformable time-dependent shape.The electrodynamic behavior of such a system is governed by the Maxwell’s equatio...For engineering electromagnetism,one of a typical case is that a medium/object rotates possibly with a deformable time-dependent shape.The electrodynamic behavior of such a system is governed by the Maxwell’s equations for a mechano-driven media system(MEs-f-MDMS).Here,by defining the effective electric and magnetic fields,the MEs-f-MDMS reduces to the stand-ard form of the Maxwell’s equations(MEs)in some engineering scenarios.This means that the accelerated motion of a medium is a source for generating electromagnetic wave,while the propagation of the waves in the system follows the classical MEs.Therefore,the standard methods for solving the MEs can be adequately applied.We first present the theoretical derivation,then we will present the solutions of the MEs-f-MDMS in both time-and frequency-space.Second,the shortcomings in classical approach regarding to the calculation of electromagnetic radiation from a rotating medium is analyzed.Third,the theory about the impact of medium rota-tion on reflection and transmission of a plane wave at an interface is considered.Fourth,the theory for quantifying the output of tri-boelectric nanogenerator is given.Fifth,since the effective fields warrant the covariance of the MEs,the Lorentz transformation can be introduced for extrapolating the effective field theory to a case there is a translation motion of the system with considering rela-tivistic effect.Finally,recent progresses about the experimental proofs in supporting the MEs-f-MDMS are covered.展开更多
基金supported by the 863 Program (Grant no.2006AA09Z323)the 973 Program (Grant No.2006CB202402)
文摘Numerical simulation in the frequency-space domain has inherent advantages, such as： it is possible to simulate wave propagation from multiple sources simultaneously; there are no cumulative errors; only the interesting frequencies can be selected; and it is more suitable for wave propagation in viscoelastic media. The only obstacle to using the method is the requirement of huge computer storage. We extend the compressed format for storing the coefficient matrix. It can reduce the required computer storage dramatically. We get the optimal coefficients by least-squares method to suppress the numerical dispersion and adopt the perfectly matched layer （PML） boundary conditions to eliminate the artificial boundary reflections. Using larger grid intervals decreases computer storage requirements and provides high computational efficiency. Numerical experiments demonstrate that these means are economic and effective, providing a good basis for elastic wave imaging and inversion.
文摘For engineering electromagnetism,one of a typical case is that a medium/object rotates possibly with a deformable time-dependent shape.The electrodynamic behavior of such a system is governed by the Maxwell’s equations for a mechano-driven media system(MEs-f-MDMS).Here,by defining the effective electric and magnetic fields,the MEs-f-MDMS reduces to the stand-ard form of the Maxwell’s equations(MEs)in some engineering scenarios.This means that the accelerated motion of a medium is a source for generating electromagnetic wave,while the propagation of the waves in the system follows the classical MEs.Therefore,the standard methods for solving the MEs can be adequately applied.We first present the theoretical derivation,then we will present the solutions of the MEs-f-MDMS in both time-and frequency-space.Second,the shortcomings in classical approach regarding to the calculation of electromagnetic radiation from a rotating medium is analyzed.Third,the theory about the impact of medium rota-tion on reflection and transmission of a plane wave at an interface is considered.Fourth,the theory for quantifying the output of tri-boelectric nanogenerator is given.Fifth,since the effective fields warrant the covariance of the MEs,the Lorentz transformation can be introduced for extrapolating the effective field theory to a case there is a translation motion of the system with considering rela-tivistic effect.Finally,recent progresses about the experimental proofs in supporting the MEs-f-MDMS are covered.
