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This work develops a nonlinear multigrid method for diffusion problems discretized by cell-centered finite volume methods on general unstructured grids. The multigrid hierarchy is constructed algebraically using aggregation of degrees of…

Numerical Analysis · Mathematics 2020-10-29 Chak Shing Lee , François Hamon , Nicola Castelletto , Panayot S. Vassilevski , Joshua White

In this paper, we present a model based on a local thermodynamic equilibrium, weakly ionized plasma-mixture model used for medical and technical applications in etching processes. We consider a simplified model based on the Maxwell-Stefan…

Numerical Analysis · Mathematics 2015-01-26 Juergen Geiser

This work focuses on numerically solving a shape identification problem related to advection-diffusion processes with space-dependent coefficients using shape optimization techniques. Two boundary-type cost functionals are considered, and…

Optimization and Control · Mathematics 2025-04-23 Elmehdi Cherrat , Lekbir Afraites , Julius Fergy Tiongson Rabago

An iterative algorithm is adopted to construct approximate representations of matrices describing the scattering properties of arbitrary objects. The method is based on the implicit evaluation of scattering responses from iteratively…

Computational Physics · Physics 2023-04-19 Johan Lundgren , Kurt Schab , Miloslav Capek , Mats Gustafsson , Lukas Jelinek

Component separation is one of the key stages of any modern, cosmic microwave background (CMB) data analysis pipeline. It is an inherently non-linear procedure and typically involves a series of sequential solutions of linear systems with…

Numerical Analysis · Mathematics 2020-07-01 J. Papež , L. Grigori , R. Stompor

Context: The solution of the nonlocal thermodynamical equilibrium (non-LTE) radiative transfer equation usually relies on stationary iterative methods, which may falsely converge in some cases. Furthermore, these methods are often unable to…

Solar and Stellar Astrophysics · Physics 2015-07-29 Julien Lambert , Eric Josselin , Nils Ryde , Alexandre Faure

Diffusion models have shown an impressive ability to model complex data distributions, with several key advantages over GANs, such as stable training, better coverage of the training distribution's modes, and the ability to solve inverse…

Computer Vision and Pattern Recognition · Computer Science 2024-06-12 Yinbo Chen , Oliver Wang , Richard Zhang , Eli Shechtman , Xiaolong Wang , Michael Gharbi

We prove optimal estimates for the decay in time of solutions to a rather general class of non-local in time subdiffusion equations in $\mathbb{R}^d$. An important special case is the time-fractional diffusion equation, which has seen much…

Analysis of PDEs · Mathematics 2014-03-10 Jukka Kemppainen , Juhana Siljander , Vicente Vergara , Rico Zacher

Thermal decay rate over an edge-shaped barrier at high dissipation is studied numerically through the computer modeling. Two sorts of the stochastic Langevin type equations are applied: (i) the Langevin equations for the coordinate and…

Nuclear Theory · Physics 2020-01-29 Maria Chushnyakova , Igor Gontchar , Alexander Zakharov , Natalya Khmyrova

A numerical method is proposed for computing time-periodic and relative time-periodic solutions in dissipative wave systems. In such solutions, the temporal period, and possibly other additional internal parameters such as the propagation…

Pattern Formation and Solitons · Physics 2014-08-28 Jianke Yang

The linearization principle states that the stability (or instability) of solutions to a suitable linearization of a nonlinear problem implies the stability (or instability) of solutions to the original nonlinear problem. In this work, we…

Analysis of PDEs · Mathematics 2025-07-04 Sofwah Ahmad , Szymon Cygan , Grzegorz Karch

In this paper we study elliptic partial differential equations with rapidly varying diffusion coefficient that can be represented as a perturbation of a reference coefficient. We develop a numerical method for efficiently solving multiple…

Numerical Analysis · Mathematics 2020-12-21 Fredrik Hellman , Tim Keil , Axel Målqvist

We present the first framework to solve linear inverse problems leveraging pre-trained latent diffusion models. Previously proposed algorithms (such as DPS and DDRM) only apply to pixel-space diffusion models. We theoretically analyze our…

Machine Learning · Computer Science 2023-07-04 Litu Rout , Negin Raoof , Giannis Daras , Constantine Caramanis , Alexandros G. Dimakis , Sanjay Shakkottai

Integro-partial differential equations occur in many contexts in mathematical physics. Typical examples include time-dependent diffusion equations containing a parameter (e.g., the temperature) that depends on integrals of the unknown…

Analysis of PDEs · Mathematics 2007-05-23 Peter A. Becker

Over the recent past data-driven algorithms for solving stochastic optimal control problems in face of model uncertainty have become an increasingly active area of research. However, for singular controls and underlying diffusion dynamics…

Optimization and Control · Mathematics 2024-10-15 Sören Christensen , Asbjørn Holk Thomsen , Lukas Trottner

We introduce a local adaptive discontinuous Galerkin method for convection-diffusion-reaction equations. The proposed method is based on a coarse grid and iteratively improves the solution's accuracy by solving local elliptic problems in…

Numerical Analysis · Mathematics 2022-01-13 Assyr Abdulle , Giacomo Rosilho de Souza

One of the main challenges in diffusion-based molecular communication is dealing with the non-linearity of reaction-diffusion chemical equations. While numerical methods can be used to solve these equations, a change in the input signals or…

Information Theory · Computer Science 2021-06-04 Hamidreza Abin , Amin Gohari , Masoumeh Nasiri-Kenari

This paper is focussed on the numerical resolution of diffusion advection and reaction equations (DAREs) with special features (such as fractures, walls, corners, obstacles or point loads) which globally, as well as locally, have important…

Numerical Analysis · Mathematics 2019-05-29 Assionvi H. Kouevi , Gabriel J. Lord

In this work, we consider an inverse problem of determining a time dependent coefficient in a fully fractional diffusion equation with a nonlinear source term. The nonlocal initial-boundary value problem refers to the forward model: the…

Analysis of PDEs · Mathematics 2025-12-10 D. K. Durdiev , H. H. Turdiev

A numerical method of solving the problem of acoustic wave radiation in the presence of a rigid scatterer is described. It combines the finite element method and the boundary algebraic equations. In the proposed method, the exterior domain…

Numerical Analysis · Computer Science 2018-05-18 J. Poblet-Puig , A. V. Shanin