Topological degree and existence of an infinite number of solutions of a boundary value problem for a singular equation. (Degré topologique et existence d'une infinité de solutions d'un problème aux limites pour une équation singulière.)
Topological sensitivity analysis for elliptic problems on graphs
Total Flux Estimates for a Finite Element Approximation of the Dirichlet Problem Using the Boundary Penalty Method.
Trace Properties of the Dirichlet Laplacian.
Transposition des problèmes aux limites elliptiques
Transposition des problèmes aux limites elliptiques
Two Families of Mixed Finite Elements for Second Order Elliptic Problems.
Two Methods of Solution of the Three-Dimensional Inverse Nodal Problem.
The operator with the Dirichlet boundary condition is considered in a parallelepiped. The problem of restoring from positions of nodal surfaces is solved.
Two preconditioners based on the multi-level splitting of finite element spaces.
Two solutions for a nonlinear Dirichlet problem with positive forcing
Given a semilinear elliptic boundary value problem having the zero solution and where the nonlinearity crosses the first eigenvalue, we perturb it by a positive forcing term; we show the existence of two solutions under certain conditions that can be weakened in the onedimensional case.
Two-sided a posteriori error estimates for linear elliptic problems with mixed boundary conditions
The paper is devoted to verification of accuracy of approximate solutions obtained in computer simulations. This problem is strongly related to a posteriori error estimates, giving computable bounds for computational errors and detecting zones in the solution domain where such errors are too large and certain mesh refinements should be performed. A mathematical model consisting of a linear elliptic (reaction-diffusion) equation with a mixed Dirichlet/Neumann/Robin boundary condition is considered...
Two-sided bounds of eigenvalues of second- and fourth-order elliptic operators
This article presents an idea in the finite element methods (FEMs) for obtaining two-sided bounds of exact eigenvalues. This approach is based on the combination of nonconforming methods giving lower bounds of the eigenvalues and a postprocessing technique using conforming finite elements. Our results hold for the second and fourth-order problems defined on two-dimensional domains. First, we list analytic and experimental results concerning triangular and rectangular nonconforming elements which...
Two-sided bounds of the discretization error for finite elements
We derive an optimal lower bound of the interpolation error for linear finite elements on a bounded two-dimensional domain. Using the supercloseness between the linear interpolant of the true solution of an elliptic problem and its finite element solution on uniform partitions, we further obtain two-sided a priori bounds of the discretization error by means of the interpolation error. Two-sided bounds for bilinear finite elements are given as well. Numerical tests illustrate our theoretical analysis....
Two-sided bounds of the discretization error for finite elements
We derive an optimal lower bound of the interpolation error for linear finite elements on a bounded two-dimensional domain. Using the supercloseness between the linear interpolant of the true solution of an elliptic problem and its finite element solution on uniform partitions, we further obtain two-sided a priori bounds of the discretization error by means of the interpolation error. Two-sided bounds for bilinear finite elements are given as well. Numerical tests illustrate our theoretical analysis. ...