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This paper is concerned with the inverse scattering problem which aims to determine the spatially distributed dielectric constant coefficient of the 2D Helmholtz equation from multifrequency backscatter data associated with a single…

Numerical Analysis · Mathematics 2020-02-25 Trung Truong , Dinh-Liem Nguyen , Michael Klibanov

We study the global convergence of the gradient descent method of the minimization of strictly convex functionals on an open and bounded set of a Hilbert space. Such results are unknown for this type of sets, unlike the case of the entire…

Numerical Analysis · Mathematics 2022-04-08 Thuy T. Le , Loc. H. Nguyen

The problem of imaging of a moving target is formulated as a Coefficient Inverse Problem for a hyperbolic equation with its coefficient depending on all three spatial variables and time. As the initial condition, the point source running…

Numerical Analysis · Mathematics 2025-12-23 Michael V. Klibanov , Jingzhi Li , Vladimir G. Romanov , Zhipeng Yang

The forward problem here is the Cauchy problem for a 1D hyperbolic PDE with a variable coefficient in the principal part of the operator. That coefficient is the spatially distributed dielectric constant. The inverse problem consists of the…

Numerical Analysis · Mathematics 2020-04-16 Alexey Smirnov , Michael Klibanov , Anders Sullivan , Lam Nguyen

The key tool of this paper is a new Carleman estimate for an arbitrary parabolic operator of the second order for the case of reversed time data. This estimate works on an arbitrary time interval. On the other hand, the previously known…

Analysis of PDEs · Mathematics 2020-01-08 Michael V. Klibanov , Anatoly G. Yagola

An approximately globally convergent numerical method for a 3d Coefficient Inverse Problem for a hyperbolic equation with backscattering data is presented. A new approximate mathematical model is presented. An approximation is used only on…

Mathematical Physics · Physics 2012-09-18 Larisa Beilina , Michael V. Klibanov

In a series of publications of the second author, including some with coauthors, globally strictly convex Tikhonov-like functionals were constructed for some nonlinear ill-posed problems. The main element of such a functional is the…

Analysis of PDEs · Mathematics 2016-08-10 Anatoly B. Bakushinskii , Michael V. Klibanov , Nikolaj A. Koshev

The first globally convergent numerical method for a Coefficient Inverse Problem (CIP) for the Riemannian Radiative Transfer Equation (RRTE) is constructed. This is a version of the so-called \textquotedblleft convexification" method, which…

Numerical Analysis · Mathematics 2023-04-13 Michael V. Klibanov , Jingzhi Li , Loc H. Nguyen , Vladimir G. Romanov , Zhipeng Yang

The reconstruction of physical properties of a medium from boundary measurements, known as inverse scattering problems, presents significant challenges. The present study aims to validate a newly developed convexification method for a 3D…

Numerical Analysis · Mathematics 2023-06-02 Thuy Le , Vo Anh Khoa , Michael Victor Klibanov , Loc Hoang Nguyen , Grant Bidney , Vasily Astratov

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

This article develops the numerical and theoretical study of a reconstruction algorithm of a potential in a wave equation from boundary measurements, using a cost functional built on weighted energy terms coming from a Carleman estimate.…

Numerical Analysis · Mathematics 2016-10-25 Lucie Baudouin , Maya de Buhan , Sylvain Ervedoza

The goal of this paper is to reconstruct spatially distributed dielectric constants from complex-valued scattered wave field by solving a 3D coefficient inverse problem for the Helmholtz equation at multi-frequencies. The data are generated…

Numerical Analysis · Mathematics 2016-12-14 Michael V. Klibanov , Dinh-Liem Nguyen , Loc H. Nguyen , Hui Liu

A 3-D inverse medium problem in the frequency domain is considered. Another name for this problem is Coefficient Inverse Problem. The goal is to reconstruct spatially distributed dielectric constants from scattering data. Potential…

Numerical Analysis · Mathematics 2016-05-23 Michael V. Klibanov , Hui Liu , Loc H. Nguyen

In this paper, a reconstruction method for the spatially distributed dielectric constant of a medium from the back scattering wave field in the frequency domain is considered. Our approach is to propose a globally convergent algorithm,…

Analysis of PDEs · Mathematics 2016-03-01 Michael V. Klibanov , Loc H. Nguyen , Anders Sullivan , Lam Nguyen

It is proposed to monitor spatial and temporal spreads of epidemics via solution of a Coefficient Inverse Problem for a system of three coupled nonlinear parabolic equations. To solve this problem numerically, a version of the so-called…

Numerical Analysis · Mathematics 2025-04-08 Michael V. Klibanov , Trung Truong

This paper is concerned with the study of a version of the globally convergent convexification method with direct application to synthetic aperture radar (SAR) imaging. Results of numerical testing are presented for experimentally collected…

Numerical Analysis · Mathematics 2021-03-22 M. V. Klibanov , V. A. Khoa , A. V. Smirnov , L. H. Nguyen , G. W. Bidney , L. H. Nguyen , A. J. Sullivan , V. N. Astratov

For the first time, a globally convergent numerical method is presented for ill-posed Cauchy problems for quasilinear PDEs. The key idea is to use Carleman Weight Functions to construct globally strictly convex Tikhonov-like cost…

Analysis of PDEs · Mathematics 2015-02-20 Michael V. Klibanov

The Calder\'on problem consists in recovering an unknown coefficient of a partial differential equation from boundary measurements of its solution. These measurements give rise to a highly nonlinear forward operator. As a consequence, the…

Analysis of PDEs · Mathematics 2025-07-02 Giovanni S. Alberti , Romain Petit , Simone Sanna

A new nonparametric estimator of a convex regression function in any dimension is proposed and its convergence properties are studied. We start by using any estimator of the regression function and we \emph{convexify} it by taking the…

Statistics Theory · Mathematics 2010-06-16 Néstor E. Aguilera , Liliana Forzani , Pedro Morin

The paper presents a globally convergent algorithm for solving coefficient inverse problems. Being rooted in the globally convergent numerical method (SIAM J. Sci. Comput., 31, No.1 (2008), pp. 478-509) for solving multidimensional…

Mathematical Physics · Physics 2013-08-30 Michael V. Klibanov , Alexandre Timonov