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In this paper, we present an inverse problem of identifying the reaction coefficient for time fractional diffusion equations in two dimensional spaces by using boundary Neumann data. It is proved that the forward operator is continuous with…

Numerical Analysis · Mathematics 2018-06-14 Xiaoyan Song , Guanghui Zheng , Lijian Jiang

This paper is devoted to the study of the existence of positive solutions for a problem related to a higher order fractional differential equation involving a nonlinear term depending on a fractional differential operator,…

Analysis of PDEs · Mathematics 2019-04-02 Pablo Álvarez-Caudevilla , Eduardo Colorado , Alejandro Ortega

Solving inverse problems with diffusion models has shown promise in tasks such as image restoration. A common approach is to formulate the problem in a Bayesian framework and sample from the posterior by combining the prior score with the…

Machine Learning · Computer Science 2025-09-30 Lingyu Wang , Xiangming Meng

We introduced and analyzed robust recovery-based a posteriori error estimators for various lower order finite element approximations to interface problems in [9, 10], where the recoveries of the flux and/or gradient are implicit (i.e.,…

Numerical Analysis · Mathematics 2014-07-17 Zhiqiang Cai , Shun Zhang

In this work, we investigate a numerical procedure for recovering a space-dependent diffusion coefficient in a (sub)diffusion model from the given terminal data, and provide a rigorous numerical analysis of the procedure. By exploiting…

Numerical Analysis · Mathematics 2024-05-20 Bangti Jin , Xiliang Lu , Qimeng Quan , Zhi Zhou

Existing approaches to diffusion-based inverse problem solvers frame the signal recovery task as a probabilistic sampling episode, where the solution is drawn from the desired posterior distribution. This framework suffers from several…

Machine Learning · Computer Science 2024-12-24 Henry Li , Marcus Pereira

In this work, we investigate the recovery of a parameter in a diffusion process given by the order of derivation in time for a class of diffusion type equations, including both classical and time-fractional diffusion equations, from the…

Analysis of PDEs · Mathematics 2021-11-04 Bangti Jin , Yavar Kian

Universal image restoration is a practical and potential computer vision task for real-world applications. The main challenge of this task is handling the different degradation distributions at once. Existing methods mainly utilize…

Computer Vision and Pattern Recognition · Computer Science 2024-03-19 Dian Zheng , Xiao-Ming Wu , Shuzhou Yang , Jian Zhang , Jian-Fang Hu , Wei-Shi Zheng

We consider one-dimensional inverse scattering in attenuating media where both the reflectivity and loss distributions are unknown. Mathematically, this corresponds to recovering the coefficients of a damped wave operator, or equivalently,…

Numerical Analysis · Mathematics 2025-11-20 Jorn Zimmerling , Mikhail Zaslavsky , Alexander V. Mamonov , Vladimir Druskin , Anarzhan Abilgazy

A radial transverse resonance model for two cylindrical concentric layers with different complex dielectric constants is presented. An inverse problem with four unknowns - 3 physical material parameters and one dimensional dielectric layer…

Optics · Physics 2016-03-24 Anders Eriksson , Truls Martin Larsen , Larisa Beilina

In this paper, we are interested in an inverse problem for the active scalar equations with fractional dissipation on the torus. We perform a second order linearization to relate our model to the linear fractional diffusion equation. Our…

Analysis of PDEs · Mathematics 2025-09-04 Li Li , Weinan Wang

In this paper, a new inversion model for 2D microwave imaging is introduced by means of a convenient rewriting of the usual Lippmann Schwinger integral scattering equation. Such model is derived by decomposing the Greens function and the…

Signal Processing · Electrical Eng. & Systems 2021-03-01 Martina T. Bevacqua , Tommaso Isernia

Inverse design problems are common in engineering and materials science. The forward direction, i.e., computing output quantities from design parameters, typically requires running a numerical simulation, such as a FEM, as an intermediate…

Machine Learning · Computer Science 2026-02-18 Jens U. Kreber , Christian Weißenfels , Joerg Stueckler

With the rapid development of diffusion models and flow-based generative models, there has been a surge of interests in solving noisy linear inverse problems, e.g., super-resolution, deblurring, denoising, colorization, etc, with generative…

Machine Learning · Computer Science 2024-10-22 Xiangming Meng , Yoshiyuki Kabashima

We study the inverse problem of unique recovery of a complex-valued scalar function $V:\mathcal M \times \mathbb C\to \mathbb C$, defined over a smooth compact Riemannian manifold $(\mathcal M,g)$ with smooth boundary, given the Dirichlet…

Analysis of PDEs · Mathematics 2023-05-10 Ali Feizmohammadi , Lauri Oksanen

Recently it has been shown that using diffusion models for inverse problems can lead to remarkable results. However, these approaches require a closed-form expression of the degradation model and can not support complex degradations. To…

Computer Vision and Pattern Recognition · Computer Science 2023-06-06 Di You , Andreas Floros , Pier Luigi Dragotti

The subdiffusion equation with a Caputo fractional derivative of order $\alpha\in(0,1)$ in time arises in a wide variety of practical applications, and it is often adopted to model anomalous subdiffusion processes in heterogeneous media.…

Numerical Analysis · Mathematics 2015-01-05 Bangti Jin , Raytcho Lazarov , Zhi Zhou

Exterior inverse problem for the circular means transform (CMT) arises in the intravascular photoacoustic imaging (IVPA), in the intravascular ultrasound imaging (IVUS), as well as in radar and sonar. The reduction of the IPVA to the CMT is…

Analysis of PDEs · Mathematics 2013-08-29 Gaik Ambartsoumian , Leonid Kunyansky

The inverse radiative transfer problem finds broad applications in medical imaging, atmospheric science, astronomy, and many other areas. This problem intends to recover the optical properties, denoted as absorption and scattering…

Numerical Analysis · Mathematics 2017-08-08 Qin Li , Ruiwen Shu , Li Wang

The sigma-convergence concept has been up to now used to derive macroscopic models in full space dimensions. In this work, we generalize it to thin heterogeneous domains given rise to phenomena in lower space dimensions. More precisely, we…

Analysis of PDEs · Mathematics 2025-12-12 Willi Jäger , Jean Louis Woukeng