Approximation of Time-Dependent Free Boundaries
Approximation of Tricomi Problem with Neumann Boundary Condition.
Approximation of viscosity solution by morphological filters
We consider in all curvature equation where G is a nondecreasing function and curv(u) is the curvature of the level line passing by x. These equations are invariant with respect to any contrast change u → g(u), with g nondecreasing. Consider the contrast invariant operator . A Matheron theorem asserts that all contrast invariant operator T can be put in a form . We show the asymptotic equivalence of both formulations. More precisely, we show that all curvature equations can be obtained...
Approximation von Eigenwertproblemen bei nichtlinearer Parameterabhängigkeit.
Approximations by the Cauchy-type integrals with piecewise linear densities
The paper is a contribution to the complex variable boundary element method, shortly CVBEM. It is focused on Jordan regions having piecewise regular boundaries without cusps. Dini continuous densities whose modulus of continuity satisfies are considered on these boundaries. Functions satisfying the Hölder condition of order , , belong to them. The statement that any Cauchy-type integral with such a density can be uniformly approximated by a Cauchy-type integral whose density is a piecewise...
Aproximación de un problema elíptico singular mediante elementos finitos isoparamétricos degenerados.
Arch beam models: finite element analysis and superconvergence.
Asymptotic and numerical modelling of flows in fractured porous media
This study concerns some asymptotic models used to compute the flow outside and inside fractures in a bidimensional porous medium. The flow is governed by the Darcy law both in the fractures and in the porous matrix with large discontinuities in the permeability tensor. These fractures are supposed to have a small thickness with respect to the macroscopic length scale, so that we can asymptotically reduce them to immersed polygonal fault interfaces and the model finally consists in a coupling between...
Asymptotic behaviour and numerical approximation of optimal eigenvalues of the Robin laplacian
We consider the problem of minimising the nth-eigenvalue of the Robin Laplacian in RN. Although for n = 1,2 and a positive boundary parameter α it is known that the minimisers do not depend on α, we demonstrate numerically that this will not always be the case and illustrate how the optimiser will depend on α. We derive a Wolf–Keller type result for this problem and show that optimal eigenvalues grow at most with n1/N, which is in sharp contrast with the Weyl asymptotics for a fixed domain. We further...
Asymptotic Error Expansion and Richardson Extrapolation for Linear Finite Elements.
Asymptotic Expansion for the Discretization Error in Linear Elliptic Boundary Value Problems on General Regions.
Asymptotic Expansions and L...-Error Estimates for Mixed Finite Element Methods for Second Order Elliptic Problems.
Asymptotic lower bounds for eigenvalues by nonconforming finite element methods.
Asymptotic lower bounds for eigenvalues of the Steklov eigenvalue problem with variable coefficients
In this paper, using a new correction to the Crouzeix-Raviart finite element eigenvalue approximations, we obtain asymptotic lower bounds of eigenvalues for the Steklov eigenvalue problem with variable coefficients on -dimensional domains (). In addition, we prove that the corrected eigenvalues converge to the exact ones from below. The new result removes the conditions of eigenfunction being singular and eigenvalue being large enough, which are usually required in the existing arguments about...
Asymptotic stability of a 9-point multigrid algorithm for convection-diffusion equations.
Asymptotic Theory of the Global Error and Some Techniques of Error Estimation.
Automatic simplification of Darcy’s equations with pressure dependent permeability
We consider the flow of a viscous incompressible fluid in a rigid homogeneous porous medium provided with mixed boundary conditions. Since the boundary pressure can present high variations, the permeability of the medium also depends on the pressure, so that the model is nonlinear. A posteriori estimates allow us to omit this dependence where the pressure does not vary too much. We perform the numerical analysis of a spectral element discretization of the simplified model. Finally we propose a strategy...
Averaging of gradient in the space of linear triangular and bilinear rectangular finite elements
An averaging method for the second-order approximation of the values of the gradient of an arbitrary smooth function u = u(x 1, x 2) at the vertices of a regular triangulation T h composed both of rectangles and triangles is presented. The method assumes that only the interpolant Πh[u] of u in the finite element space of the linear triangular and bilinear rectangular finite elements from T h is known. A complete analysis of this method is an extension of the complete analysis concerning the finite...
Axissymmetric Free Surface Seepage
Aппроксимация обобщенных решений с помощью конечных разностей