Sur la diacaustique d'une surface plane
Sur la propagation des ondes lumineuses, eu égard à la dispersion
Sur la réfraction des gaz
Sur le système de Nernst-Planck-Poisson-Boltzmann résultant de l’homogénéisation par convergence à double échelle
Le système d’évolution de Nernst-Planck-Poisson-Boltzmann modélise les transferts ioniques en milieu poreux saturé en prenant en compte des interactions électrocapillaires au contact du substrat. Ce modèle présente un intérêt particulier en génie civil pour étudier la dégradation par corrosion des matériaux cimentaires, à structure micro-locale périodique, sous l’effet des ions chlorures. Les techniques d’homogénéisation sont alors un outil puissant pour élaborer un modèle macroscopique équivalent...
Sur les fibrés d'objets géométriques et leurs applications physiques
Sur les lois qui régissent, à une première approximation, les ondes lumineuses propagées dans un milieu homogène et transparent d'une contexture quelconque.
Sur les modifications qu'éprouve la lumière par suite du mouvement de la source lumineuse et du mouvement de l'observateur
Sur les modifications qu'éprouve la lumière par suite du mouvement de la source lumineuse et du mouvement de l'observateur (deuxième partie)
Sur un problème de stabilité posé en optique géométrique non linéaire surcritique
Cet exposé s’intéresse à un modèle réaliste issu de la mécanique des fluides. L’objectif est de montrer qu’il est possible de traiter dans un tel cadre des problèmes d’instabilité soulevés par la propagation de singularités qualifiées de surcritiques. D’abord, nous introduisons le modèle (équations de type Navier-Stokes) et ses motivations (questions liées à la propagation d’oscillations en régime turbulent). Ensuite, nous présentons deux résultats (relatifs au caractère bien posé d’un problème...
Sur une méthode d'autocollimation directe des objectifs astronomiques et son application à la mesure des indices de réfraction; remarques sur l'emploi du sphéromètre
Symmetric caustics and Curie's principle
Physical systems producing caustics may possess symmetries. In that case the relation between the symmetry of the system, considered as a whole, and the symmetry of the caustic follow a very general symmetry principle, the Curie principle. We give various examples of application of the Curie principle to caustics produced by the deflection of light in liquid crystals: the so called squint effect, the visualization of a new type of roll structure, etc. We show also that the Curie principle applies...
Symplectic local time-stepping in non-dissipative DGTD methods applied to wave propagation problems
The Discontinuous Galerkin Time Domain (DGTD) methods are now popular for the solution of wave propagation problems. Able to deal with unstructured, possibly locally-refined meshes, they handle easily complex geometries and remain fully explicit with easy parallelization and extension to high orders of accuracy. Non-dissipative versions exist, where some discrete electromagnetic energy is exactly conserved. However, the stability limit of the methods, related to the smallest elements in the mesh,...
Symplectic local time-stepping in non-dissipative DGTD methods applied to wave propagation problems
The Discontinuous Galerkin Time Domain (DGTD) methods are now popular for the solution of wave propagation problems. Able to deal with unstructured, possibly locally-refined meshes, they handle easily complex geometries and remain fully explicit with easy parallelization and extension to high orders of accuracy. Non-dissipative versions exist, where some discrete electromagnetic energy is exactly conserved. However, the stability limit of the methods, related to the smallest elements in the mesh,...
Tangential fields in mathematical model of optical diffraction
We present the formulation of optical diffraction problem on periodic interface based on vector tangential fields, for which the system of boundary integral equations is established. Obtained mathematical model is numerically solved using boundary element method and applied to sine interface profile.
T-coercivity for scalar interface problems between dielectrics and metamaterials
Some electromagnetic materials have, in a given frequency range, an effective dielectric permittivity and/or a magnetic permeability which are real-valued negative coefficients when dissipation is neglected. They are usually called metamaterials. We study a scalar transmission problem between a classical dielectric material and a metamaterial, set in an open, bounded subset of Rd, with d = 2,3. Our aim is to characterize occurences where the problem is well-posed within the Fredholm (or coercive...
T-coercivity for scalar interface problems between dielectrics and metamaterials
Some electromagnetic materials have, in a given frequency range, an effective dielectric permittivity and/or a magnetic permeability which are real-valued negative coefficients when dissipation is neglected. They are usually called metamaterials. We study a scalar transmission problem between a classical dielectric material and a metamaterial, set in an open, bounded subset of Rd, with d = 2,3. Our aim is to characterize occurences where the problem is well-posed within the Fredholm (or coercive...
Temporal convergence of a locally implicit discontinuous Galerkin method for Maxwell’s equations
In this paper we study the temporal convergence of a locally implicit discontinuous Galerkin method for the time-domain Maxwell’s equations modeling electromagnetic waves propagation. Particularly, we wonder whether the method retains its second-order ordinary differential equation (ODE) convergence under stable simultaneous space-time grid refinement towards the true partial differential equation (PDE) solution. This is not a priori clear due to the component splitting which can introduce order...
Temporal convergence of a locally implicit discontinuous Galerkin method for Maxwell’s equations∗
In this paper we study the temporal convergence of a locally implicit discontinuous Galerkin method for the time-domain Maxwell’s equations modeling electromagnetic waves propagation. Particularly, we wonder whether the method retains its second-order ordinary differential equation (ODE) convergence under stable simultaneous space-time grid refinement towards the true partial differential equation (PDE) solution. This is not a priori clear due to the component splitting which can introduce order...
Teorie nového zapojení elektronkového oscilátoru
The boundary-value problem for the transport equation with purely Compton scattering.