Ray tracing is a basic aspect in tomography. To solve the caustic problem in inhomogeneous media using Maslov asymptotic theory, we need to calculate the position and slowness vector at every point. Therefore, ray tra...
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Ray tracing is a basic aspect in tomography. To solve the caustic problem in inhomogeneous media using Maslov asymptotic theory, we need to calculate the position and slowness vector at every point. Therefore, ray tracing must rely on the ray equations in Hamiltonian form. In this paper, fourth order symplectic scheme and nonsymplectic Runge-Kutta scheme are compared in ray tracing for sinusoidal velocity model. The result indicates that ray paths obtained by two schemes are almost the same. But on keeping Hamilton quantities, the symplectic scheme is far better than the Runge-Kutta scheme. On computing travel time for Htamiltonian system with T parameter, we use trapezoid formula for numerical integration. The result coincides with that obtained using Hamiltonian system with t parameter.
In this paper we discuss the natural boundary element method for harmonic equation in an exterior elliptic domain. By studying the properties of the natural integral operator and the Poisson integral operator, we deve...
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In this paper we discuss the natural boundary element method for harmonic equation in an exterior elliptic domain. By studying the properties of the natural integral operator and the Poisson integral operator, we develop a numerical method to solve the natural integral equation. We also devise a fast algorithm for the solution of the corresponding system of linear equations. Finally we present some numerical results.
The paper presents a posteriori error estimate of FD-SD method for one- dimension time-dependent convection- dominated diffusion equation 5 which can be used to adjust space mesh. Some numerical results and an algorit...
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The paper presents a posteriori error estimate of FD-SD method for one- dimension time-dependent convection- dominated diffusion equation 5 which can be used to adjust space mesh. Some numerical results and an algorithm of adaptive finite element method based on this a posteriori error estimate are given.
The finite element methods for the second type variational inequality deduced from the simplified contact problem with friction have been considered by *** et al [2]. In this note, the modified finite element method w...
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The finite element methods for the second type variational inequality deduced from the simplified contact problem with friction have been considered by *** et al [2]. In this note, the modified finite element method with numerical integration for this problem is considered, and the error estimate is improved.
In this paper, based on the problems studied in [1], the discrete schemes of the coupling of FEM and BEM for the nonlinear parabolic equations are given. The existence of the approximation solution, and stability resu...
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In this paper, based on the problems studied in [1], the discrete schemes of the coupling of FEM and BEM for the nonlinear parabolic equations are given. The existence of the approximation solution, and stability results and corresponding error estimates are discussed in detail. Finally, the numerical example is provided, and numerical results show that the method is feasible and effective.
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