Logarithmic stabilization of the Euler-Bernoulli transmission plate equation with locally distributed Kelvin-Voigt damping

In this paper we will study the asymptotic behaviour of the energy decay of a transmission plate equation with locally distributed Kelvin-Voigt feedback. Precisly, we shall prove that the energy decay at least logarithmically over the time. The originality of this method comes from the fact that using a Carleman estimate for a transmission second order system which will be derived from the plate equation to establish a resolvent estimate which provide, by the famous Burq's result [Bur98], the kind of decay mentionned above.Comment: 16 pages, 1 figure. arXiv admin note: substantial text overlap with arXiv:1301.353

Mean value property associated with the Dunkl Laplacian

Let $\Delta_k$ be the Dunkl Laplacian on $\mathbb{R}^d$. The main goal of this paper is to characterize $\Delta_k$-harmonic functions by means of a mean value propertyComment: 10 page

Rapid exponential stabilization of a 1-D transmission wave equation with in-domain anti-damping

We consider the problem of pointwise stabilization of a one-dimensional wave equation with an internal spatially varying anti-damping term. We design a feedback law based on the backstepping method and prove exponential stability of the closed-loop system with a desired decay rate.Comment: 15 page

Weak stabilization of a transmission Euler-Bernoulli plate equation with force and moment feedback

In this paper we will study the asymptotic behaviour of the energy decay of a transmission plate equation with force and moment feedback. Precisly, we shall prove that the energy decay at least logarithmically over the time. The method consist to use the classical second order Carleman estimate to estabish a resolvent estimate which provide by the famous Burq's result [Bur98] the kind of decay above mentionned.Comment: 15 pages, 2 figure

Potential theory associated with the Dunkl Laplacian

The main goal of this paper is to give potential theoretical approach to study the Dunkl Laplacian $\Delta_k$ which is a standard example of differential-difference operators. By introducing the Green kernel relative to $\Delta_k$, we prove that the Dunkl Laplacian generates a balayage space and we investigate the associated family of harmonic measures. Therefore, by mean of harmonic kernels, we give a characterization of all $\Delta_k$-harmonic functions on large class of open subsets $U$ of $\mathbb{R}^d$. We also establish existence and uniqueness result of a solution of the corresponding Dirichlet problem.Comment: 21 page

Energy decay estimates of elastic transmission wave/beam systems with a local Kelvin-Voigt damping

We consider a beam and a wave equations coupled on an elastic beam through transmission conditions. The damping which is locally distributed acts through one of the two equations only; its effect is transmitted to the other equation through the coupling. First we consider the case where the dissipation acts through the beam equation. Using a recent result of Borichev and Tomilov on polynomial decay characterization of bounded semigroups we provide a precise decay estimates showing that the energy of this coupled system decays polynomially as the time variable goes to infinity. Second, we discuss the case where the damping acts through the wave equation. Proceeding as in the first case, we prove that this system is also polynomially stable and we provide precise polynomial decay estimates for its energy. Finally, we show the lack of uniform exponential decay of solutions for both models.Comment: 28 pages. arXiv admin note: text overlap with arXiv:1812.0592

A fast reconstruction algorithm for geometric inverse problems using topological sensitivity analysis and Dirichlet-Neumann cost functional approach

This paper is concerned with the detection of objects immersed in anisotropic media from boundary measurements. We propose an accurate approach based on the Kohn-Vogelius formulation and the topological sensitivity analysis method. The inverse problem is formulated as a topology optimization one minimizing an energy like functional. A topological asymptotic expansion is derived for the anisotropic Laplace operator. The unknown object is reconstructed using a level-set curve of the topological gradient. The efficiency and accuracy of the proposed algorithm are illustrated by some numerical results. MOTS-CL\'ES : Probl\`eme inverse g\'eom\'etrique, Laplace anisotrope, formulation de Kohn-Vogelius, analyse de sensibilit\'e, optimisation topologique

Stabilization of fractional-evolution systems

This paper is devoted to the analysis of the problem of stabilization of fractional (in time) partial differential equations. We consider the following equation $$\partial^{\alpha,\eta}_{t} u(t)=\mathcal{A}u(t)-\frac{\eta}{\Gamma (1-\alpha)}\int_{0}^{t}(t-s)^{-\alpha} \, e^{-\eta(t-s)}u(s)\, ds,\; t > 0,$$ with the initial data $u(0)=u^{0}$, where $\mathcal{A}$ is a unbounded operator in Hilbert space and $\partial_{t}^{\alpha,\eta}$ stands for the fractional derivative. We provide two main results concerning the behavior of the solutions when $t\longrightarrow+\infty$. We look first to the case $\eta>0$ where we prove that the solution of this problem is exponential stable then we consider the case $\eta=0$ when we prove under some consideration on the resolvent that the energy of the solution goes to $0$ as $t$ goes to the infinity as $1/t^\alpha$

A non-iterative reconstruction method for an inverse problem modeled by a Stokes-Brinkmann equations

This article is concerned with the reconstruction of obstacle \O immersed in a fluid flowing in a bounded domain $\Omega$ in the two dimensional case. We assume that the fluid motion is governed by the Stokes-Brinkmann equations. We make an internal measurement and then have a least-square approach to locate the obstacle. The idea is to rewrite the reconstruction problem as a topology optimization problem. The existence and the stability of the optimization problem are demonstrated. We use here the concept of the topological gradient in order to determine the obstacle and it's rough location. The topological gradient is computed using a straightforward way based on a penalization technique without the truncation method used in the literature. The unknown obstacle is reconstructed using a level-set curve of the topological gradient. Finally, we make some numerical examples exploring the efficiency of the method

Some constructions of multiplicative nn-ary Hom-Nambu algebras

We show that given a Hom-Lie algebra one can construct the n-ary Hom-Lie bracket by means of an (n-2)-cochain of given Hom-Lie algebra and find the conditions under which this n-ary bracket satisfies the Filippov-Jacobi identity, there by inducing the structure of n-Hom-Lie algebra. We introduce the notion of Hom-Lie $n$-uplet system which is the generalization of Hom-Lie triple system. We construct Hom-Lie $n$-uplet system using a Hom-Lie algebra.Comment: arXiv admin note: text overlap with arXiv:1605.08281 by other author