Existence d'états stationnaires pour l'équation de Dirac non linéaire
Existence of conservation laws in nilpotent case.
Experimental comparison of traffic flow models on traffic data
Despite their deficiencies, continuous second-order traffic flow models are still commonly used to derive discrete-time models that help traffic engineers to model and predict traffic oflow behaviour on highways. We brie fly overview the development of traffic flow theory based on continuous flow-density models of Lighthill-Whitham-Richards (LWR) type, that lead to the second-order model of Aw-Rascle. We will then concentrate on widely-adopted discrete approximation to the LWR model by Daganzo's...
Failure of convergence of the Lax-Oleinik semi-group in the time periodic case
Funzioni -convesse
We study a class of functions which differ essentially from those which are the sum of a convex function and a regular one and which have interesting properties related to -convergence and to problems with non-convex constraints. In particular some results are given for the associated evolution equations.
Generalized solutions by Cauchy's method of characteristics
Germes de configurations legendriennes stables et fonctions d'Airy-Weber généralisées
On sait depuis Maslov, Arnold, etc... associer à presque tout germe de variété lagrangienne ou legendrienne lisse une classe de fonctions oscillantes qui sous des hypothèses génériques à la Thom fournissent des modèles universels pour le comportement d’une onde lumineuse au voisinage de la caustique.Le présent article étend cette construction à une classe de situations où la variété caractéristique est un germe singulier (union de composantes lisses), qui peut néanmoins être stable en ce sens que...
Global existence for non-linear partial differential equations of the first order
Global subanalytic solutions of Hamilton–Jacobi type equations
Interface cinétique / fluide : Un modèle simplifié
Invariants of characteristics of some systems of partial differential equations.
KAM techniques in PDE
Layering methods for nonlinear partial differential equations of first order
This paper is concerned with generalized, discontinuous solutions of initial value problems for nonlinear first order partial differential equations. “Layering” is a method of approximating an arbitrary generalized solution by dividing its domain, say a half-space , into thin layers , , and using a strict solution in the -th layer. On the interface , is required to reduce to a smooth function approximating the values on that plane of . The resulting stratified configuration of strict solutions...
Limites hydrodynamiques de l'équation de Boltzmann
Limites réversibles et irréversibles de systèmes de particules.
Il s’agit de comparer les différents résultats et théorèmes concernant dans un cadre essentiellement déterministe des systèmes de particules. Cela conduit à étudier la notion de hiérarchies d’équations et à comparer les modèles non linéaires et linéaires. Dans ce dernier cas on met en évidence le rôle de l’aléatoire. Ce texte réfère à une série de travaux en collaboration avec F. Golse, A. Gottlieb, D. Levermore et N. Mauser.
Linear programming interpretations of Mather’s variational principle
We discuss some implications of linear programming for Mather theory [13, 14, 15] and its finite dimensional approximations. We find that the complementary slackness condition of duality theory formally implies that the Mather set lies in an -dimensional graph and as well predicts the relevant nonlinear PDE for the “weak KAM” theory of Fathi [6, 7, 8, 5].
Linear programming interpretations of Mather's variational principle
We discuss some implications of linear programming for Mather theory [13-15] and its finite dimensional approximations. We find that the complementary slackness condition of duality theory formally implies that the Mather set lies in an n-dimensional graph and as well predicts the relevant nonlinear PDE for the “weak KAM” theory of Fathi [5-8].
Nachtrag. Directe Ableitung des Lie'schen Fundamentaltheorems durch die Methode von Cauchy
New and old function spaces in the theory of PDEs and nonlinear analysis
Nonlinear boundary value problems describing mobile carrier transport in semiconductor devices
The present paper describes mobile carrier transport in semiconductor devices with constant densities of ionized impurities. For this purpose we use one-dimensional partial differential equations. The work gives the proofs of global existence of solutions of systems of such kind, their bifurcations and their stability under the corresponding assumptions.