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Diffusion models have been widely studied as effective generative tools for solving inverse problems. The main ideas focus on performing the reverse sampling process conditioned on noisy measurements, using well-established numerical…

Numerical Analysis · Mathematics 2024-10-29 Xiang Cao , Xiaoqun Zhang

Diffusion model-based inverse problem solvers have demonstrated state-of-the-art performance in cases where the forward operator is known (i.e. non-blind). However, the applicability of the method to blind inverse problems has yet to be…

Computer Vision and Pattern Recognition · Computer Science 2022-11-22 Hyungjin Chung , Jeongsol Kim , Sehui Kim , Jong Chul Ye

Higher resolution telescopes as well as 3D numerical simulations will require the development of detailed 3D radiative transfer calculations. Building upon our previous work we extend our method to include both continuum and line transfer.…

Astrophysics · Physics 2009-11-13 E. Baron , Peter H. Hauschildt

Purpose: To introduce a novel deep learning based approach for fast and high-quality dynamic multi-coil MR reconstruction by learning a complementary time-frequency domain network that exploits spatio-temporal correlations simultaneously…

Image and Video Processing · Electrical Eng. & Systems 2021-06-21 Chen Qin , Jinming Duan , Kerstin Hammernik , Jo Schlemper , Thomas Küstner , René Botnar , Claudia Prieto , Anthony N. Price , Joseph V. Hajnal , Daniel Rueckert

Solving the inverse problem is the key step in evaluating the capacity of a physical model to describe real phenomena. In medical image computing, it aligns with the classical theme of image-based model personalization. Traditionally, a…

A new approach for the parallel forward modeling of transient electromagnetic (TEM) fields is presented. It is based on a family of uniform-in-time rational approximants to the matrix exponential that share a common denominator independent…

Numerical Analysis · Mathematics 2025-06-16 Ralph-Uwe Börner , Stefan Güttel

This paper proposes a parallel-in-time method for computing continuous-time maximum-a-posteriori (MAP) trajectory estimates of the states of partially observed stochastic differential equations (SDEs), with the goal of improving…

Distributed, Parallel, and Cluster Computing · Computer Science 2025-12-16 Hassan Razavi , Ángel F. García-Fernández , Simo Särkkä

A numerical scheme is proposed for the solution of the three-dimensional radiative transfer equation with variable optical depth. We show that time-dependent ray tracing is an attractive choice for simulations of astrophysical ionization…

Astrophysics · Physics 2009-10-31 Alexei Razoumov , Douglas Scott

The subset sum problem is a typical NP-complete problem that is hard to solve efficiently in time due to the intrinsic superpolynomial-scaling property. Increasing the problem size results in a vast amount of time consuming in…

Emerging Technologies · Computer Science 2020-02-13 Xiao-Yun Xu , Xuan-Lun Huang , Zhan-Ming Li , Jun Gao , Zhi-Qiang Jiao , Yao Wang , Ruo-Jing Ren , H. P. Zhang , Xian-Min Jin

We present an algorithm for solving the radiative transfer problem on massively parallel computers using adaptive mesh refinement and domain decomposition. The solver is based on the method of characteristics which requires an adaptive…

Astrophysics of Galaxies · Physics 2015-08-13 Lars Buntemeyer , Robi Banerjee , Thomas Peters , Mikhail Klassen , Ralph E. Pudritz

We describe a parallel solver for the discretized weakly singular space-time boundary integral equation of the spatially two-dimensional heat equation. The global space-time nature of the system matrices leads to improved parallel…

Numerical Analysis · Mathematics 2021-02-23 Stefan Dohr , Michal Merta , Günther Of , Olaf Steinbach , Jan Zapletal

The dose of X-ray radiation and the scanning time are crucial factors in computed tomography (CT) for clinical applications. In this work, we introduce a multi-source static CT imaging system designed to rapidly acquire sparse view and…

Medical Physics · Physics 2025-01-03 Ziju Shen , Haimiao Zhang , Bin Dong , Jun Qiu , Yunxiang Li , Zhili Cui

We present a new numerical scheme to solve the transfer of diffuse radiation on three-dimensional mesh grids which is efficient on processors with highly parallel architecture such as recently popular GPUs and CPUs with multi- and many-core…

Instrumentation and Methods for Astrophysics · Physics 2015-05-27 Satoshi Tanaka , Kohji Yoshikawa , Takashi Okamoto , Kenji Hasegawa

Inverse source problems arise often in real-world applications, such as localizing unknown groundwater contaminant sources. Being different from Tikhonov regularization, the quasi-boundary value method has been proposed and analyzed as an…

Numerical Analysis · Mathematics 2022-01-11 Yi Jiang , Jun Liu , Xiang-Sheng Wang

We shall derive and propose several efficient overlapping domain decomposition methods for solving some typical linear inverse problems, including the identiffication of the flux, the source strength and the initial temperature in second…

Numerical Analysis · Mathematics 2013-09-10 Jiang Daijun , Feng Hui , Zou Jun

When solving the time-dependent radiative transport equation (RTE), implicit time discretization is often employed for its robustness and stability. This results in a sequence of steady-state RTEs with identical cross-sections but varying…

Numerical Analysis · Mathematics 2026-04-24 Qinchen Song , Lei Zhang , Min Tang

The motivation of this work is the detection of cerebrovascular accidents by microwave tomographic imaging. This requires the solution of an inverse problem relying on a minimization algorithm (for example, gradient-based), where successive…

Computational Engineering, Finance, and Science · Computer Science 2020-03-23 P. -H. Tournier , I. Aliferis , M. Bonazzoli , M. de Buhan , M. Darbas , V. Dolean , F. Hecht , P. Jolivet , I. El Kanfoud , C. Migliaccio , F. Nataf , C. Pichot , S. Semenov

The main disadvantage of Magnetic Resonance Imaging (MRI) are its long scan times and, in consequence, its sensitivity to motion. Exploiting the complementary information from multiple receive coils, parallel imaging is able to recover…

Numerical Analysis · Computer Science 2017-03-07 Martin Uecker

We consider the geometric optics problem of finding a system of two reflectors that transform a spherical wavefront into a beam of parallel rays with prescribed intensity distribution. Using techniques from optimal transportation theory, it…

Numerical Analysis · Mathematics 2011-11-08 Tilmann Glimm , Nick Henscheid