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排序方式: 共有7591条查询结果,搜索用时 140 毫秒
991.
Summary In the first part of this paper we are dealing with theoretical statements and conditions which lead to existence and uniqueness of the solution of a nonlinear boundary value problem with delay. Next we apply this method successfully to a numerical example. The computations have been carried out at the computer Siemens 4004. The data obtained are presented in two tables. 相似文献
992.
Kurt Georg 《Numerische Mathematik》1979,32(1):69-74
Summary In recent years, a group of inverse iteration type algorithms have been developed for solving nonlinear elliptic eigenvalue problems in plasma physics [4]. Although these algorithms have been very successful in practice, no satisfactory theoretical justification of convergence has been available. The present paper fills this gap and proves for a large class of such problems and a simple version of such algorithms that linear convergence to a local maximum of a certain potential is obtained.This work was supported by the Deutsche Forschungsgemeinschaft, SFB 72 an der Universität Bonn 相似文献
993.
The finite element method is used to solve a second order elliptic boundary value problem on a polygonal domain. Mesh refinements and weighted Besov spaces are used to obtain optimal error estimates and inverse theorems.Research performed while at the University of Maryland under a Fulbright fellowshipResearch supported in part by the Department of Energy under the contract E(40-1)3443Research supported in part by the National Institutes of Health under the grant 5R01-AM-20373 相似文献
994.
J. P. Milaszewicz 《Numerische Mathematik》1982,38(1):53-59
Summary By means of successive partial substitutions it is possible to obtain new fixed point linear equations from old ones and it is interesting to determine how the spectral radius of the corresponding matrices varies. We prove that, when the original matrix is nonnegative, this variation is decreasing or increasing, depending on whether the original matrix has its spectral radius smaller or greater than 1. We answer in this way a question posed by F. Robert in [5]. 相似文献
995.
On the numerical solution of a logarithmic integral equation of the first kind for the Helmholtz equation 总被引:1,自引:0,他引:1
Summary We describe a quadrature method for the numerical solution of the logarithmic integral equation of the first kind arising from the single-layer approach to the Dirichlet problem for the two-dimensional Helmholtz equation in smooth domains. We develop an error analysis in a Sobolev space setting and prove fast convergence rates for smooth boundary data. 相似文献
996.
Summary. In this paper, we consider the problem of designing plate-bending elements which are free of shear locking. This phenomenon is known to afflict several elements for the Reissner-Mindlin plate model when the thickness of the plate is small, due to the inability of the approximating subspaces to satisfy the Kirchhoff constraint. To avoid locking, a “reduction operator” is often applied to the stress, to modify the variational formulation and reduce
the effect of this constraint. We investigate the conditions required on such reduction operators to ensure that the approximability
and consistency errors are of the right order. A set of sufficient conditions is presented, under which optimal errors can
be obtained – these are derived directly, without transforming the problem via a Hemholtz decomposition, or considering it
as a mixed method. Our analysis explicitly takes into account boundary layers and their resolution, and we prove, via an asymptotic
analysis, that convergence of the finite element approximations will occur uniformly as , even on quasiuniform meshes. The analysis is carried out in the case of a free boundary, where the boundary layer is known
to be strong. We also propose and analyze a simple post-processing scheme for the shear stress. Our general theory is used
to analyze the well-known MITC elements for the Reissner-Mindlin plate. As we show, the theory makes it possible to analyze
both straight and curved elements. We also analyze some other elements.
Received June 19, 1995 相似文献
997.
We define a 1-parameter family ofr-matrices on the loop algebra of sl2, defining compatible Poisson structures on the associated loop group, which degenerate into the rational and trigonometric structures, and study the Manin triples associated with them.To our friend Dimitri Gurevich, on his 50th birthday 相似文献
998.
The Cauchy problem to an equation arising in modeling the motion of viscous droplets is studied in the present paper. The authors prove that if the initial data has compact support, then there exists a weak solution which has compact support for all the time. 相似文献
999.
Carlos Conca 《Numerische Mathematik》1984,45(1):75-91
Résumé Nous présentons dans cet article une méthode d'éléments finis mixtes qui permet la résolution des équations de Stokes avec des conditions aux limites de type Fourier ou Neumann. Pour cette méthode nous démontrons que les estimations de l'erreur d'approximation sont optimales; en vitesse et en pression. Ces résultats de convergences généralisent à ce type non standard de conditions aux limites les travaux de Glowinski-Pironneau [9, 10] pour le probleme de Stokes avec des conditions aux limites de Dirichlet.
Mixed-finite element approximation of stokes type problems
Summary We present in this paper a mixed-finite element approximation of Stokes equations with boundary conditions of Fourier's or Neumann's type. For this approximation we prove that the error estimates for the velocity-vector and for the pressure are optimal. These results of convergence generalize to this kind of boundary conditions the Glowinski-Pironneau's approximation of Stokes problem with Dirichlet's boundary conditions [9, 10].相似文献
1000.
J. J. M. Cuppen 《Numerische Mathematik》1984,45(3):403-409
Summary In this paper it is shown how a triangular product of Householder reflections can be updated with an arbitrary elementary orthogonal transformation. The amount of work required is 5/2n
2 multiplications for absorbing an arbitrary reflection and 3n
2 multiplications for absorbing a plane rotation on subsequent indices. 相似文献