The wave front set of oscillatory integrals with inhomogeneous phase function

A generalized notion of oscillatory integrals that allows for inhomogeneous phase functions of arbitrary positive order is introduced. The wave front set of the resulting distributions is characterized in a way that generalizes the well-known result for phase functions that are homogeneous of order one.Comment: 12 pages, published versio

Trace ideals for Fourier integral operators with non-smooth symbols II

We consider Fourier integral operators with symbols in modulation spaces and non-smooth phase functions whose second orders of derivatives belong to certain types of modulation space. We establish continuity and Schatten-von Neumann properties of such operators when acting on modulation spaces.Comment: 25 page

Asymptotic Density of Eigenvalue Clusters for the Perturbed Landau Hamiltonian

We consider the Landau Hamiltonian (i.e. the 2D Schroedinger operator with constant magnetic field) perturbed by an electric potential V which decays sufficiently fast at infinity. The spectrum of the perturbed Hamiltonian consists of clusters of eigenvalues which accumulate to the Landau levels. Applying a suitable version of the anti-Wick quantization, we investigate the asymptotic distribution of the eigenvalues within a given cluster as the number of the cluster tends to infinity. We obtain an explicit description of the asymptotic density of the eigenvalues in terms of the Radon transform of the perturbation potential V.Comment: 30 pages. The explicit dependence on B and V in Theorem 1.6 (i) - (ii) indicated. Typos corrected. To appear in Communications in Mathematical Physic

Approximation of Fourier Integral Operators by Gabor multipliers

A general principle says that the matrix of a Fourier integral operator with respect to wave packets is concentrated near the curve of propagation. We prove a precise version of this principle for Fourier integral operators with a smooth phase and a symbol in the Sjoestrand class and use Gabor frames as wave packets. The almost diagonalization of such Fourier integral operators suggests a specific approximation by (a sum of) elementary operators, namely modified Gabor multipliers. We derive error estimates for such approximations. The methods are taken from time-frequency analysis.Comment: 22. page

Abstract composition laws and their modulation spaces

On classes of functions defined on R^2n we introduce abstract composition laws modelled after the pseudodifferential product of symbols. We attach to these composition laws modulation mappings and spaces with useful algebraic and topological properties.Comment: 19 page

Operateurs differentiels et conjugaison par des operateurs integraux de Fourier

SIGLET 55598 / INIST-CNRS - Institut de l'Information Scientifique et TechniqueFRFranc

Sur une formule de dérivée de forme dans la théorie de Brunn-Minkowski

We extend a formula for the computation of the shape derivative of an integral cost functional with respect to a class of convex domains, using the so called support functions and gauge functions to express it. This is a priori a formula in shape optimization theory. However, the result also happens to be an extension of a well known formula from the Brunn-Minkowski theory of convex bodies.Nous généralisons une formule donnant la dérivée de forme d'une fonctionnelle coût par rapport à une classe de domaines convexes, en utilisant ce que l'on appelle fonctions support et fonctions jauge pour l'exprimer. C'est a priori une formule intervenant en optimisation de formes. Cependant, il se trouve qu'elle généralise aussi une formule bien connue dans la théorie de Brunn-Minkowski des corps convexes

On a shape derivative formula for a family of star-shaped domains

In this work, we consider again the shape derivative formula for a volume cost functional which we studied in preceding papers where we used the Minkowski deformation and the support functions in the convex setting. Here, we extend it to some non convex domains, namely the star-shaped ones. The formula also happens to be an extension of a well known formula in the Brunn-Minkowski theory. Finally, we illustrate the formula by applying it to the computation of the shape derivative for a shape optimization problem and by giving an algorithm based on the gradient method

On a numerical shape optimization approach for a class of free boundary problems

This paper is devoted to a numerical method for the approximation of a class of free boundary problems of Bernoulli's type, reformulated as optimal shape design problems with appropriate shape functionals. We show the existence of the shape derivative of the cost functional on a class of admissible domains and compute its shape derivative by using the formula proposed in [5, 6], that is, by means of support functions. On the numerical level, this allows us to avoid the tedious computations of the method based on vector fields. A gradient method combined with boundary element method are performed for the approximation of this problem, in order to overcome the re-meshing task required by the finite element method. Finally, we present some numerical results and simulations concerning practical applications, showing the effectiveness of the proposed approach