In this paper, the backward problem of a parabolic equation is considered. Three new stability estimates are given. Based on the new stability estimates, a regularization method is proposed for which error estimates a...In this paper, the backward problem of a parabolic equation is considered. Three new stability estimates are given. Based on the new stability estimates, a regularization method is proposed for which error estimates are available. The regularization method can be used for the numerical approximations of the original problem which will be shown by the numerical examples.展开更多
Alternating direction implicit (A.D.I.) schemes have been proved valuable in the approximation of the solutions of parabolic partial differential equations in multi-dimensional space. Consider equations in the form pa...Alternating direction implicit (A.D.I.) schemes have been proved valuable in the approximation of the solutions of parabolic partial differential equations in multi-dimensional space. Consider equations in the form partial derivative u/partial derivative t - partial derivative/partial derivative x(a(x,y,t) partial derivative u/partial derivative x) - partial derivative/partial derivative y(b(x,y,t) partial derivative u partial derivative y) = f Two A.D.I. schemes, Peaceman-Rachford scheme and Douglas scheme will be studied. In the literature, stability and convergence have been analysed with Fourier Method, which cannot be extended beyond the model problem with constant coefficients. Additionally, L-2 energy method has been introduced to analyse the case of non-constant coefficients, however, the conclusions are too weak and incomplete because of the so-called 'equivalence between L-2 norm and H-1 semi-norm'. In this paper, we try to improve these conclusions by H-1 energy estimating method. The principal results are that both of the two A.D.I. schemes are absolutely stable and converge to the exact solution with error estimations O(Delta t(2) + h(2)) in discrete H-1 norm. This implies essential improvement of existing conclusions.展开更多
In this paper,a new discontinuous Galerkin method is developed for the parabolic equation with jump coefficients satisfying the continuous flow condition.Theoretical analysis shows that this method is L^(2) stable.Whe...In this paper,a new discontinuous Galerkin method is developed for the parabolic equation with jump coefficients satisfying the continuous flow condition.Theoretical analysis shows that this method is L^(2) stable.When the finite element space consists of interpolative polynomials of degrees k,the convergent rate of the semi-discrete discontinuous Galerkin scheme has an order of δ(h^(k)).Numerical examples for both 1-dimensional and 2-dimensional problems demonstrate the validity of the new method.展开更多
For the backward diffusion equation,a stable discrete energy regularization algorithm is proposed.Existence and uniqueness of the numerical solution are given.Moreover,the error between the solution of the given backw...For the backward diffusion equation,a stable discrete energy regularization algorithm is proposed.Existence and uniqueness of the numerical solution are given.Moreover,the error between the solution of the given backward diffusion equation and the numerical solution via the regularization method can be estimated.Some numerical experiments illustrate the efficiency of the method,and its application in image deblurring.展开更多
基金This work was supported partly by the Special Funds for Major State Basic Reseach Projects of China and the Na-tional Natural Science Foundation of China
文摘In this paper, the backward problem of a parabolic equation is considered. Three new stability estimates are given. Based on the new stability estimates, a regularization method is proposed for which error estimates are available. The regularization method can be used for the numerical approximations of the original problem which will be shown by the numerical examples.
文摘Alternating direction implicit (A.D.I.) schemes have been proved valuable in the approximation of the solutions of parabolic partial differential equations in multi-dimensional space. Consider equations in the form partial derivative u/partial derivative t - partial derivative/partial derivative x(a(x,y,t) partial derivative u/partial derivative x) - partial derivative/partial derivative y(b(x,y,t) partial derivative u partial derivative y) = f Two A.D.I. schemes, Peaceman-Rachford scheme and Douglas scheme will be studied. In the literature, stability and convergence have been analysed with Fourier Method, which cannot be extended beyond the model problem with constant coefficients. Additionally, L-2 energy method has been introduced to analyse the case of non-constant coefficients, however, the conclusions are too weak and incomplete because of the so-called 'equivalence between L-2 norm and H-1 semi-norm'. In this paper, we try to improve these conclusions by H-1 energy estimating method. The principal results are that both of the two A.D.I. schemes are absolutely stable and converge to the exact solution with error estimations O(Delta t(2) + h(2)) in discrete H-1 norm. This implies essential improvement of existing conclusions.
基金supported by the National Natural Science Foundation of China(Grant No:10771019,11171038)supported by the Young Talent Attraction program of Brazilian National Council for Scientific and Technological Development(CNPq).
文摘In this paper,a new discontinuous Galerkin method is developed for the parabolic equation with jump coefficients satisfying the continuous flow condition.Theoretical analysis shows that this method is L^(2) stable.When the finite element space consists of interpolative polynomials of degrees k,the convergent rate of the semi-discrete discontinuous Galerkin scheme has an order of δ(h^(k)).Numerical examples for both 1-dimensional and 2-dimensional problems demonstrate the validity of the new method.
基金National Natural Science Foundation of China(No.10471073)。
文摘For the backward diffusion equation,a stable discrete energy regularization algorithm is proposed.Existence and uniqueness of the numerical solution are given.Moreover,the error between the solution of the given backward diffusion equation and the numerical solution via the regularization method can be estimated.Some numerical experiments illustrate the efficiency of the method,and its application in image deblurring.
