Determination of conductivity in a heat equation.
Dynamical instability of symmetric vortices.
Using the Maxwell-Higgs model, we prove that linearly unstable symmetric vortices in the Ginzburg-Landau theory are dynamically unstable in the H1 norm (which is the natural norm for the problem).In this work we study the dynamic instability of the radial solutions of the Ginzburg-Landau equations in R2 (...)
Enhanced electrical impedance tomography via the Mumford–Shah functional
We consider the problem of electrical impedance tomography where conductivity distribution in a domain is to be reconstructed from boundary measurements of voltage and currents. It is well-known that this problem is highly illposed. In this work, we propose the use of the Mumford–Shah functional, developed for segmentation and denoising of images, as a regularization. After establishing existence properties of the resulting variational problem, we proceed by demonstrating the approach in several...
Enhanced Electrical Impedance Tomography via the Mumford–Shah Functional
We consider the problem of electrical impedance tomography where conductivity distribution in a domain is to be reconstructed from boundary measurements of voltage and currents. It is well-known that this problem is highly illposed. In this work, we propose the use of the Mumford–Shah functional, developed for segmentation and denoising of images, as a regularization. After establishing existence properties of the resulting variational problem, we proceed by demonstrating the approach in several...
Error estimates of a difference approximation method for a backward heat conduction problem.
Estimates for a solution to one differential inequality.
Exemples d’instabilités pour des équations d’ondes non linéaires
Le but de l’exposé est de donner un guide de lecture pour un article de Gilles Lebeau où il est montré que le problème de Cauchy pour l’équation d’onde surcritique est mal posé au sens de Hadamard dans l’espace d’énergie, pour en dimension 3. La preuve repose sur des constructions d’optique géométrique et des analyses d’instabilité dans des régimes fortement non linéaires. On donnera les étapes de l’analyse en essayant de les situer dans leur contexte plus général : construction de solutions...
Ill-posed Cauchy problems for ideal gas equations and their regularization
Ill-posedness of the Cauchy problem for totally degenerate system of conservation laws.
Iterative schemes for almost linear eppiptic systems with nonlinear initial data.
Limite de la solution de ut - ∆um + div F(u) = 0 lorsque m --> ∞.
Dans cette article, on étudie la limite lorsque m --> ∞ de la solution du problème de Cauchy ut - ∆um + div F(u) = 0 sur un ouvert Omega avec des conditions aux bords de type Dirichlet et une donnée initiale u0 ≥ 0.
Linear instability implies nonlinear instability for various types of viscous boundary layers
Local ill-posedness of the 1D Zakharov system.
Nonexistence of Global Weak Solutions to Some Properly and Improperly Posed Problems of Mathematical Physics: The Method of Unbounded Fourier Coefficients.
Nonlinear models for laser-plasma interaction
In this paper, we present a nonlinear model for laser-plasma interaction describing the Raman amplification. This system is a quasilinear coupling of several Zakharov systems. We handle the Cauchy problem and we give some well-posedness and ill-posedness result for some subsystems.
On an initial inverse problem in nonlinear heat equation associated with time-dependent coefficient
In this paper, a nonlinear backward heat problem with time-dependent coefficient in the unbounded domain is investigated. A modified regularization method is established to solve it. New error estimates for the regularized solution are given under some assumptions on the exact solution.
On Hadamard's concepts of correctness
On polynomials of Sheffer type arising from a Cauchy problem.
On some improperly posed problem for a degenerate nonlinear parabolic equation.
On stability and growth of solutions for classes of initial and boundary value problems