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We consider backward problems for semilinear coupled parabolic systems in bounded domains. We prove conditional stability estimates for linear and semilinear systems of strongly coupled parabolic equations involving general semilinearities.…

Analysis of PDEs · Mathematics 2024-05-07 S. E. Chorfi , M. Yamamoto

In the discrete setting of one-dimensional finite-differences we prove a Carleman estimate for a semi-discretization of the parabolic operator $\partial_t-\partial_x (c\partial_x)$ where the diffusion coefficient $c$ has a jump. As a…

Optimization and Control · Mathematics 2012-11-12 Thuy Nguyen

In this article, we present a novel Carleman estimate for ultrahyperbolic operators, in $ \mathbb{R}^m_t \times \mathbb{R}^n_x $. Then, we use a special case of this estimate to obtain improved observability results for wave equations with…

Analysis of PDEs · Mathematics 2021-10-19 Vaibhav Kumar Jena

For a symmetric hyperbolic system of the first order, we prove a Carleman estimate under some positivity condition concerning the coefficient matrices. Next, applying the Carleman estimate, we prove an observability $L^2$-estimate for…

Analysis of PDEs · Mathematics 2025-04-15 G. Floridia , H. Takase , M. Yamamoto

In this work, we prove a Carleman estimate for a parabolic problem which has a dissipative degenerate term. The prove relies on choose a suitable weight function that change of sign inside the control domain.

Analysis of PDEs · Mathematics 2020-10-28 R. Demarque , J. Límaco , L. Viana

This paper is devoted to studying null controllability for a class of stochastic fourth order semi-discrete parabolic equations, where the spatial variable is discretized with finite difference scheme and the time is kept as a continuous…

Optimization and Control · Mathematics 2024-05-07 Yu Wang , Qingmei Zhao

In this article, we extensively develop Carleman estimates for the wave equation and give some applications. We focus on the case of an observation of the flux on a part of the boundary satisfying the Gamma conditions of Lions. We will then…

Analysis of PDEs · Mathematics 2013-10-11 Lucie Baudouin , Maya De Buhan , Sylvain Ervedoza

In this paper, we study the null controllability for a stochastic semilinear CahnHilliard type equation, whose semilinear term contains first and second order derivatives of solutions. To start with, an improved global Carleman estimate for…

Optimization and Control · Mathematics 2024-08-08 Sen Zhang , Hang Gao , Ganghua Yuan

In this article, we provide a modified argument for proving conditional stability for inverse problems of determining spatially varying functions in evolution equations by Carleman estimates. Our method needs not any cut-off procedures and…

Analysis of PDEs · Mathematics 2020-12-30 X. Huang , O. Yu. Imanuvilov , M. Yamamoto

In this note, we establish a new Carleman estimate with singular weights for the sub-Laplacian on a Carnot group $\mathbb G$ for functions satisfying the discrepancy assumption in (2.16) below. We use such an estimate to derive a sharp…

Analysis of PDEs · Mathematics 2022-05-06 Vedansh Arya , Dharmendra Kumar

We propose a globally convergent computational technique for the nonlinear inverse problem of reconstructing the zero-order coefficient in a parabolic equation using partial boundary data. This technique is called the "reduced dimensional…

Numerical Analysis · Mathematics 2023-09-27 Ray Abney , Thuy T. Le , Loc H. Nguyen , Cam Peters

For an initial-boundary value problem for a parabolic equation in the spatial variable $x=(x_1,.., x_n)$ and time $t$, we consider an inverse problem of determining a coefficient which is independent of one spatial component $x_n$ by extra…

Analysis of PDEs · Mathematics 2020-09-22 Oleg Yu. Imanuvilov , Yavar Kian , Masahiro Yamamoto

It is shown that the contraction mapping principle with the involvement of a Carleman Weight Function works for a Coefficient Inverse Problem for a 1D hyperbolic equation. Using a Carleman estimate, the global convergence of the…

Numerical Analysis · Mathematics 2022-03-23 Thuy T. Le , Michael V. Klibanov , Loc H. Nguyen , Anders Sullivan , Lam Nguyen

We consider a first-order transport equation $\ppp_tu(x,t) + (H(x)\cdot\nabla u(x,t)) + p(x)u(x,t) = F(x,t)$ for $x \in \OOO \subset \R^d$, where $\OOO$ is a bounded domain and $0<t<T$. We prove a Carleman estimate for more generous…

Analysis of PDEs · Mathematics 2025-07-24 P. Cannarsa , G. Floridia , M. Yamamoto

We propose a new iterative scheme to compute the numerical solution to an over-determined boundary value problem for a general quasilinear elliptic PDE. The main idea is to repeatedly solve its linearization by using the quasi-reversibility…

Numerical Analysis · Mathematics 2022-05-02 Thuy T. Le , Loc H. Nguyen , Hung V. Tran

In this paper, we present a new Carleman estimate for the adjoint equations associated to a class of super strong degenerate parabolic linear problems. Our approach considers a standard geometric imposition on the control domain, which can…

Analysis of PDEs · Mathematics 2022-04-22 Bruno S. V. Araújo , Reginaldo Demarque , Luiz Viana

In this paper, we focus on the analysis of discrete versions of the Calderon problem with partial boundary data in dimension d >= 3. In particular, we establish logarithmic stability estimates for the discrete Calderon problem on an…

Analysis of PDEs · Mathematics 2024-05-14 Xiaomeng Zhao , Ganghua Yuan

This work is concerned with the obtainment of new Carleman estimates for linear parabolic equations, where the second-order differential operator brings a super strong degeneracy in a positive measure subset of the spatial domain. In order…

Analysis of PDEs · Mathematics 2024-04-22 Bruno S. V. Araújo , Reginaldo Demarque , Josiane C. O. Faria , Luiz Viana

This paper concerns about the weak unique continuation property of solutions of a general system of differential equation/inequality with a second order strongly elliptic system as its leading part. We put not only some natural assumption…

Analysis of PDEs · Mathematics 2015-05-19 N. Honda , C. -L. Lin , G. Nakamura , S. Sasayama

In this work, we present methods for state estimation in continuous-discrete nonlinear systems involving stochastic differential equations. We present the extended Kalman filter, the unscented Kalman filter, the ensemble Kalman filter, and…