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In this paper, we develop a framework for the discretization of a mixed formulation of quasi-reversibility solutions to ill-posed problems with respect to Poisson's equations. By carefully choosing test and trial spaces a formulation that…

Numerical Analysis · Mathematics 2024-10-01 Erik Burman , Mingfei Lu

In this paper we propose a new class of iterative regularization methods for solving ill-posed linear operator equations. The prototype of these iterative regularization methods is in the form of second order evolution equation with a…

Numerical Analysis · Mathematics 2020-06-24 Rongfang Gong , B. Hofmann , Ye Zhang

In this paper, we announce a rigorous approach to establishing uniqueness results, under certain conditions, for initial-boundary-value problems for a class of linear evolution partial differential equations (PDEs) formulated in a…

Analysis of PDEs · Mathematics 2024-01-17 Andreas Chatziafratis , Spyridon Kamvissis

An ill-posed inverse problem of autoconvolution type is investigated. This inverse problem occurs in nonlinear optics in the context of ultrashort laser pulse characterization. The novelty of the mathematical model consists in a physically…

Mathematical Physics · Physics 2013-01-28 Daniel Gerth , Bernd Hofmann , Simon Birkholz , Sebastian Koke , Günter Steinmeyer

In my previaou paper of K. Horihata, we have proposed a Ginzburg-Landau system with a time-dependent parameter and then passing to the limit we have constructed a harmonic heat flow into spheres. Thanks to this scheme, we establish a few…

Analysis of PDEs · Mathematics 2015-08-03 Kazuhiro Horihata

The inverse conductivity problem aims at determining the unknown conductivity inside a bounded domain from boundary measurements. In practical applications, algorithms based on minimizing a regularized residual functional subject to PDE…

Numerical Analysis · Mathematics 2025-10-02 Lefu Cai , Zhixin Liu , Minghui Song , Xianchao Wang

We address the inverse problem of identifying a time-dependent potential coefficient in a one-dimensional diffusion equation subject to Dirichlet boundary conditions and a nonlocal integral overdetermination constraint reflecting spatially…

Numerical Analysis · Mathematics 2025-11-12 Arshyn Altybay , Michael Ruzhansky

A singularly perturbed linear system of second order ordinary differential equations of reaction-diffusion type with given boundary conditions is considered. The leading term of each equation is multiplied by a small positive parameter.…

Numerical Analysis · Mathematics 2009-06-23 M. Paramasivam , S. Valarmathi , J. J. H. Miller

We study the inverse problem of recovering a spatially dependent variable order in a time-fractional diffusion model from the boundary flux measurement generated by a single boundary excitation. It arises in the identification of…

Analysis of PDEs · Mathematics 2026-02-27 Jiho Hong , Bangti Jin , Yavar Kian

A mathematical model of the heat process in one-dimensional domain governed by a cylindrical heat equation with a heat source on the axis $z=0$ and nonlinear thermal coefficients is considered. The developed model is particularly applicable…

Analysis of PDEs · Mathematics 2023-11-07 Julieta Bollati , Adriana C. Briozzo , Stanislav N. Kharin , Targyn A. Nauryz

This paper considers a local and non-local problem characterized by singular nonlinearity and a source term. Specifically, we focus on the following problem: \begin{equation}\label{A}\tag{P} -\Delta_{p} u + (-\Delta)^{s}_{q} u = f(x)…

Analysis of PDEs · Mathematics 2024-11-05 Abdelhamid Gouasmia

Although the \emph{residual method}, or \emph{constrained regularization}, is frequently used in applications, a detailed study of its properties is still missing. This sharply contrasts the progress of the theory of Tikhonov…

Optimization and Control · Mathematics 2012-12-06 Markus Grasmair , Markus Haltmeier , Otmar Scherzer

The capacitance of capacitive energy storage devices can not be directly measured, but can be estimated from the input and output signals expressed in the time or frequency domains. Here the time-domain voltage-charge relationship in…

Applied Physics · Physics 2023-03-08 Anis Allagui , Ahmed Elwakil

In the paper, we propose an analytical and numerical approach to identify scalar parameters (coefficients, orders of fractional derivatives) in the multi-term fractional differential operator in time, $\mathbf{D}_t$. To this end, we analyze…

Analysis of PDEs · Mathematics 2026-04-07 Andrii Hulianytskyi , Sergei Pereverzyev , Sergii Siryk , Nataliya Vasylyeva

The purpose of this study is to propose a high-accuracy and fast numerical method for the Cauchy problem of the Laplace equation. Our problem is directly discretized by the method of fundamental solutions (MFS). The Tikhonov regularization…

Numerical Analysis · Mathematics 2009-11-13 Takemi Shigeta , D. L. Young

To comprehend complex systems with multiple states, it is imperative to reveal the identity of these states by system outputs. Nevertheless, the mathematical models describing these systems often exhibit nonlinearity so that render the…

Machine Learning · Computer Science 2023-07-04 Guangtao Zhang , Yiting Duan , Guanyu Pan , Qijing Chen , Huiyu Yang , Zhikun Zhang

We study the inverse problem of parameter identification in non-coercive variational problems that commonly appear in applied models. We examine the differentiability of the set-valued parameter-to-solution map by using the first-order and…

Optimization and Control · Mathematics 2018-08-08 Christian Clason , Akhtar A. Khan , Miguel Sama , Christiane Tammer

In this study, we focus on identifying solution and an unknown space-dependent coefficient in a space-time fractional differential equation by employing fractional Taylor series method. The substantial advantage of this method is that we…

Analysis of PDEs · Mathematics 2021-06-08 Mine Aylin Bayrak , Ali Demir

This work considers a nonlinear inverse source problem in a coupled diffusion equation from the terminal observation. Theoretically, under some conditions on problem data, we build the uniqueness theorem for this inverse problem and show…

Numerical Analysis · Mathematics 2025-04-29 Chunlong Sun , Wenlong Zhang , Zhidong Zhang

In this paper we consider the training of single hidden layer neural networks by pseudoinversion, which, in spite of its popularity, is sometimes affected by numerical instability issues. Regularization is known to be effective in such…

Neural and Evolutionary Computing · Computer Science 2015-08-26 Rossella Cancelliere , Mario Gai , Patrick Gallinari , Luca Rubini