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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

The paper proposes a novel regularization procedure for machine learning. The proposed high-order regularization (HR) provides new insight into regularization, which is widely used to train a neural network that can be utilized to…

Machine Learning · Computer Science 2025-05-14 Xinghua Liu , Ming Cao

We consider efficient methods for computing solutions to dynamic inverse problems, where both the quantities of interest and the forward operator (measurement process) may change at different time instances but we want to solve for all the…

Numerical Analysis · Mathematics 2021-07-14 Mirjeta Pasha , Arvind K. Saibaba , Silvia Gazzola , Malena I. Espanol , Eric de Sturler

In a number of tomographic applications, data cannot be fully acquired, resulting in a severely underdetermined image reconstruction. In such cases, conventional methods lead to reconstructions with significant artifacts. To overcome these…

Numerical Analysis · Mathematics 2023-06-21 Simon Göppel , Jürgen Frikel , Markus Haltmeier

Electron tomography is a powerful tool for understanding the morphology of materials in three dimensions, but conventional reconstruction algorithms typically suffer from missing-wedge artifacts and data misalignment imposed by experimental…

Image and Video Processing · Electrical Eng. & Systems 2025-12-10 Cedric Lim , Corneel Casert , Arthur R. C. McCray , Serin Lee , Andrew Barnum , Jennifer Dionne , Colin Ophus

For high precision in source reconstruction of magnetoencephalography (MEG) or electroencephalography data, high accuracy of the coregistration of sources and sensors is mandatory. Usually, the source space is derived from magnetic…

Medical Physics · Physics 2020-08-06 Hermann Sonntag , Jens Haueisen , Burkhard Maess

We consider the estimation of the regularization parameter for the simultaneous deblurring of multiple noisy images via Tikhonov regularization. We approach the problem in three ways. We first reduce the problem to a single-image deblurring…

Astrophysics · Physics 2009-11-10 R. Vio , P. Ma , W. Zhong , J. Nagy , L. Tenorio , W. Wamsteker

A two-dimensional tomographic problem is studied. The target is assumed to be a homogeneous object bounded by a smooth curve. A Non Uniform Rational Basis Splines (NURBS) curve is used as computational representation of the boundary. This…

Numerical Analysis · Mathematics 2017-08-08 Heikki Haario , Aki Kallonen , Marko Laine , Esa Niemi , Zenith Purisha , Samuli Siltanen

This paper concerns the inverse source scattering problems of recovering random sources for acoustic and elastic waves. The underlying sources are assumed to be random functions driven by an additive white noise. The inversion process aims…

Numerical Analysis · Mathematics 2024-12-10 Yan Chang , Yukun Guo , Zhipeng Yang , Yue Zhao

Background: Extensions of single-reference (SR) energy-density-functionals (EDFs) to multi-reference (MR) applications involve using the generalized Wick theorem (GWT), which leads to singular energy kernels that cannot be properly…

Nuclear Theory · Physics 2014-12-09 Wojciech Satula , Jacek Dobaczewski

The standard approach for photoacoustic imaging with variable speed of sound is time reversal, which consists in solving a well-posed final-boundary value problem for the wave equation backwards in time. This paper investigates the…

Optimization and Control · Mathematics 2016-03-17 Zakaria Belhachmi , Thomas Glatz , Otmar Scherzer

We propose a new image restoration model based on the minimized surface regularization. The proposed model closely relates to the classical smoothing ROF model \cite{4}. We can reformulate the proposed model as a min-max problem and solve…

Optimization and Control · Mathematics 2016-05-31 Zhi-Feng Pang , Yuping Duan

Higher-order tensors can represent scores in a rating system, frames in a video, and images of the same subject. In practice, the measurements are often highly quantized due to the sampling strategies or the quality of devices. Existing…

Machine Learning · Computer Science 2020-10-28 Ren Wang , Meng Wang , Jinjun Xiong

Image reconstruction of EIT mathematically is a typical nonlinear and severely ill-posed inverse problem. Appropriate priors or penalties are required to enable the reconstruction. The commonly used L2-norm can enforce the stability to…

Numerical Analysis · Mathematics 2018-03-13 Jing Wang , Bo Han , Wei Wang

The problem of reconstructing the spatial support of an extended radiating electric current source density in a lossy dielectric medium from transient boundary measurements of the electric fields is studied. A time reversal algorithm is…

Mathematical Physics · Physics 2014-09-19 Abdul Wahab , Amer Rasheed , Tasawar Hayat , Rab Nawaz

We investigate the weighted Group Lasso formulation for the static inverse electroencephalography (EEG) problem, aiming at reconstructing the unknown underlying neuronal sources from voltage measurements on the scalp. By modelling the three…

Numerical Analysis · Mathematics 2025-12-17 Ole Løseth Elvetun , Bjørn Fredrik Nielsen , Niranjana Sudheer

Recent studies highlight the potential of textual modalities in conditioning the speech separation model's inference process. However, regularization-based methods remain underexplored despite their advantages of not requiring auxiliary…

Audio and Speech Processing · Electrical Eng. & Systems 2025-08-06 Tsun-An Hsieh , Heeyoul Choi , Minje Kim

Parallel MRI is a fast imaging technique that enables the acquisition of highly resolved images in space. It relies on $k$-space undersampling and multiple receiver coils with complementary sensitivity profiles in order to reconstruct a…

We propose a double obstacle phase field methodology for binary recovery of the slowness function of an Eikonal equation found in first traveltime tomography. We treat the inverse problem as an optimization problem with quadratic misfit…

Numerical Analysis · Mathematics 2019-09-04 Oliver R. A. Dunbar , Charles M. Elliott

Dynamic inverse problems are challenging to solve due to the need to identify and incorporate appropriate regularization in both space and time. Moreover, the very large scale nature of such problems in practice presents an enormous…

Numerical Analysis · Mathematics 2025-01-23 Toluwani Okunola , Mirjeta Pasha , Misha Kilmer , Melina Freitag