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Inverse problems are characterized by their inherent non-uniqueness and sensitivity with respect to data perturbations. Their stable solution requires the application of regularization methods including variational and iterative…

Numerical Analysis · Mathematics 2023-10-17 Aviv Gibali , Markus Haltmeier

Source identification problems have multiple applications in engineering such as the identification of fissures in materials, determination of sources in electromagnetic fields or geophysical applications, detection of contaminant sources,…

Numerical Analysis · Mathematics 2021-11-12 Guillermo F. Umbricht , Diana Rubio , Claudio El Hasi

X-ray tomography is a reliable tool for determining the inner structure of 3D object with penetrating X-rays. However, traditional reconstruction methods such as FDK require dense angular sampling in the data acquisition phase leading to…

Solving inverse problems requires appropriate regularization techniques to ensure well-posedness and stability. In recent years, denoiser-driven methods have emerged as effective regularization strategies, achieving state-of-the-art…

Numerical Analysis · Mathematics 2026-04-23 Harshit Bajpai , Ankik Kumar Giri , Tim Jahn , Abhinav Jha

This paper focuses on the regularization of backward time-fractional diffusion problem on unbounded domain. This problem is well-known to be ill-posed, whence the need of a regularization method in order to recover stable approximate…

Numerical Analysis · Mathematics 2022-01-03 Walter Simo Tao Lee

We consider a particular approach to the regularization of the inverse problem of computerized tomography. This approach is based on notions pertaining to Fourier synthesis. It refines previous contributions, in which the preprocessing of…

Optimization and Control · Mathematics 2014-01-30 Pierre Maréchal , Abdelhadi Elasmai

In this article we study the problem of recovering the unknown solution of a linear ill-posed problem, via iterative regularization methods. We review the problem of projection-regularization from a statistical point of view. A basic…

Statistics Theory · Mathematics 2007-06-13 Ana K. Fermin , Carenne Ludena

This paper aims to solve numerically the two-dimensional inverse medium scattering problem with far-field data. This is a challenging task due to the severe ill-posedness and strong nonlinearity of the inverse problem. As already known, it…

Numerical Analysis · Mathematics 2025-09-25 Kai Li , Bo Zhang , Haiwen Zhang

Polynomial factorization in conventional sense is an ill-posed problem due to its discontinuity with respect to coefficient perturbations, making it a challenge for numerical computation using empirical data. As a regularization, this paper…

Numerical Analysis · Mathematics 2021-03-09 Wenyuan Wu , Zhonggang Zeng

The problem of an accurate tip radius and shape characterization is very important for determination of surface mechanical and chemical properties on the basis of the scanning probe microscopy measurements. We think that the most favorable…

Instrumentation and Detectors · Physics 2011-05-10 G. Jozwiak , A. Henrykowski , A. Masalska , T. Gotszalk , I. Ritz , H. Steigmann

Manifold regularization methods for matrix factorization rely on the cluster assumption, whereby the neighborhood structure of data in the input space is preserved in the factorization space. We argue that using the k-neighborhoods of all…

Machine Learning · Computer Science 2020-10-21 Priya Mani , Carlotta Domeniconi , Igor Griva

Recently, convex formulations of low-rank matrix factorization problems have received considerable attention in machine learning. However, such formulations often require solving for a matrix of the size of the data matrix, making it…

Machine Learning · Computer Science 2017-08-29 Benjamin D. Haeffele , Rene Vidal

Selecting the best regularization parameter in inverse problems is a classical and yet challenging problem. Recently, data-driven approaches have become popular to tackle this challenge. These approaches are appealing since they do require…

Statistics Theory · Mathematics 2025-10-22 Jonathan Chirinos Rodriguez , Ernesto De Vito , Cesare Molinari , Lorenzo Rosasco , Silvia Villa

This paper is concerned with the inverse problem of reconstructing an inhomogeneous medium from the acoustic far-field data at a fixed frequency in two dimensions. This inverse problem is severely ill-posed (and also strongly nonlinear),…

Numerical Analysis · Mathematics 2023-09-21 Kai Li , Bo Zhang , Haiwen Zhang

The characteristic feature of inverse problems is their instability with respect to data perturbations. In order to stabilize the inversion process, regularization methods have to be developed and applied. In this work we introduce and…

Numerical Analysis · Mathematics 2022-08-22 Andrea Ebner , Jürgen Frikel , Dirk Lorenz , Johannes Schwab , Markus Haltmeier

A sampling method by using scattering amplitude is proposed for shape and location reconstruction in inverse acoustic scattering problems. Only matrix multiplication is involved in the computation, thus the novel sampling method is very…

Numerical Analysis · Mathematics 2017-09-13 Xiaodong Liu

This article presents a mathematical study of the problem of identifying a time-dependent source term in transport processes described by a timefractional parabolic equation, based on noisy time-dependent measurements taken at an arbitrary…

Analysis of PDEs · Mathematics 2026-04-06 Guillermo Federico Umbricht , Diana Rubio

Owing to the edge preserving ability and low computational cost of the total variation (TV), variational models with the TV regularization have been widely investigated in the field of multiplicative noise removal. The key points of the…

Computer Vision and Pattern Recognition · Computer Science 2015-03-18 Dai-Qiang Chen , Li-Zhi Cheng

This paper is concerned with backward problem for nonlinear space fractional diffusion with additive noise on the right-hand side and the final value. To regularize the instable solution, we develop some new regularized method for solving…

Analysis of PDEs · Mathematics 2016-12-19 Erkan Nane , Nguyen Huy Tuan

In this article, we study several reconstruction methods for the inverse source problem of photoacoustic tomography (PAT) with spatially variable sound speed and damping. The backbone of these methods is the adjoint operators, which we…

Analysis of PDEs · Mathematics 2018-08-21 Linh V. Nguyen , Markus Haltmeier