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Displaying 81 –
100 of
303
Since matrix compression has paved the way for discretizing the boundary integral
equation formulations of electromagnetics scattering on very fine meshes, preconditioners
for the resulting linear systems have become key to efficient simulations. Operator
preconditioning based on Calderón identities has proved to be a powerful device for
devising preconditioners. However, this is not possible for the usual first-kind boundary
formulations for electromagnetic...
Dans l'article, on a donné quelques conditions suffisantes pour l'unicité locale et globale de la solution du problème. On a construit une solution variationnelle du problème par la méthode de Newton-Kantorovitch et la méthode du prolongement continu avec ces conditions suffisantes pour l'unicité.
We recall the definition of Minimizing Movements, suggested by E. De Giorgi, and we consider some applications to evolution problems. With regards to ordinary differential equations, we prove in particular a generalization of maximal slope curves theory to arbitrary metric spaces. On the other hand we present a unifying framework in which some recent conjectures about partial differential equations can be treated and solved. At the end we consider some open problems.
We consider the Fourier first boundary value problem for an infinite system of weakly coupled nonlinear differential-functional equations. To prove the existence and uniqueness of solution, we apply a monotone iterative method using J. Szarski's results on differential-functional inequalities and a comparison theorem for infinite systems.
Finite element approximation for degenerate parabolic equations is considered. We propose a semidiscrete scheme provided with order-preserving and contraction properties, making use of piecewise linear trial functions and the lumping mass technique. Those properties allow us to apply nonlinear semigroup theory, and the wellposedness and stability in and , respectively, of the scheme are established. Under certain hypotheses on the data, we also derive convergence without any convergence rate....
Finite element approximation for degenerate parabolic equations is
considered.
We propose a semidiscrete scheme provided with order-preserving
and L1 contraction properties, making use of piecewise linear
trial functions and the lumping mass technique.
Those properties allow us to apply nonlinear semigroup theory,
and the wellposedness and stability in L1 and L∞,
respectively, of the scheme are established.
Under certain hypotheses on the data, we also derive L1
convergence without any...
In this paper we deal with a problem of segmentation (including missing boundary completion) and subjective contour creation. For the corresponding models we apply the semi-implicit finite volume numerical schemes leading to methods which are robust, efficient and stable without any restriction to a time step. The finite volume discretization enables to use the spatial adaptivity and thus improve significantly the computational time. The computational results related to image segmentation with partly...
We consider the numerical investigation of two hyperbolic shallow water models. We focus on the treatment of the hyperbolic part. We first recall some efficient finite volume solvers for the classical Saint-Venant system. Then we study their extensions to a new multilayer Saint-Venant system. Finally, we use a kinetic solver to perform some numerical tests which prove that the 2D multilayer Saint-Venant system is a relevant alternative to D hydrostatic Navier-Stokes equations.
We propose a numerical analysis of proper orthogonal decomposition (POD) model reductions in which a priori error estimates are expressed in terms of the projection errors that are controlled in the construction of POD bases. These error estimates are derived for generic parabolic evolution PDEs, including with non-linear Lipschitz right-hand sides, and for wave-like equations. A specific projection continuity norm appears in the estimates and – whereas a general uniform continuity bound seems out...
We propose a numerical analysis of proper orthogonal decomposition (POD) model reductions in which a priori error estimates are expressed in terms of the projection errors that are controlled in the construction of POD bases. These error estimates are derived for generic parabolic evolution PDEs, including with non-linear Lipschitz right-hand sides, and for wave-like equations. A specific projection continuity norm appears in the estimates and – whereas a general uniform continuity bound seems out...
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303