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We consider the numerical solution of coupled volume-surface reaction-diffusion systems having a detailed balance equilibrium. Based on the conservation of mass, an appropriate quadratic entropy functional is identified and an…

Numerical Analysis · Mathematics 2015-11-04 Herbert Egger , Klemens Fellner , Jan-Frederik Pietschmann , Bao Quoc Tang

The diffusion of a reactant to a binding target plays a key role in many biological processes. The reaction-radius at which the reactant and target may interact is often a small parameter relative to the diameter of the domain in which the…

Subcellular Processes · Quantitative Biology 2016-10-26 Sam Isaacson , Ava Mauro , Jay Newby

We are interested in the kernel of one-dimensional diffusion equations with continuous coefficients as evaluated by means of explicit discretization schemes of uniform step $h>0$ in the limit as $h\to0$. We consider both semidiscrete…

Numerical Analysis · Mathematics 2007-11-02 Claudio Albanese

We consider the finite volume approximation of a reaction-diffusion system with fast reversible reaction. We deduce from a priori estimates that the approximate solution converges to the weak solution of the reaction-diffusion problem and…

Analysis of PDEs · Mathematics 2008-08-05 R. Eymard , D. Hilhorst , M. Olech

An implicit finite difference scheme based on the $L2$-$1_{\sigma}$ formula is presented for a class of one-dimensional time fractional reaction-diffusion equations with variable coefficients and time drift term. The unconditional stability…

Numerical Analysis · Mathematics 2020-02-12 Yong-Liang Zhao , Pei-Yong Zhu , Xian-Ming Gu , Xi-Le Zhao

In this paper, we consider the approximate controllability of partial differential equations with time derivatives of non-integer order via boundary control. We first show the unique existence of the solution under smooth boundary…

Optimization and Control · Mathematics 2015-01-07 Kenichi Fujishiro

This article is in continuation of our earlier article [37] in which computational solution of an unified reaction-diffusion equation of distributed order associated with Caputo derivatives as the time-derivative and Riesz-Feller derivative…

Analysis of PDEs · Mathematics 2012-11-02 R. K. Saxena , A. M. Mathai , H. J. Haubold

Although the spatially continuous version of the reaction-diffusion equation has been well studied, in some instances a spatially-discretized representation provides a more realistic approximation of biological processes. Indeed,…

Dynamical Systems · Mathematics 2023-11-27 Jacqueline M. Wentz , David M. Bortz

In this paper, we consider a class of optimal control problems for a one-dimensional time-discrete constrained quasilinear diffusion state-systems of singular Allen--Cahn types and its regularized approximating problems. We note that the…

Optimization and Control · Mathematics 2021-09-28 Shodai Kubota

Diffusion models have emerged as powerful tools for generative modeling, demonstrating exceptional capability in capturing target data distributions from large datasets. However, fine-tuning these massive models for specific downstream…

Machine Learning · Computer Science 2025-09-01 Yinbin Han , Meisam Razaviyayn , Renyuan Xu

We couple the L1 discretization for Caputo derivative in time with spectral Galerkin method in space to devise a scheme that solves quasilinear subdiffusion equations. Both the diffusivity and the source are allowed to be nonlinear…

Numerical Analysis · Mathematics 2022-11-30 Łukasz Płociniczak

We develop an encounter-based approach for describing restricted diffusion with a gradient drift towards a partially reactive boundary. For this purpose, we introduce an extension of the Dirichlet-to-Neumann operator and use its eigenbasis…

Chemical Physics · Physics 2022-10-10 Denis S. Grebenkov

We show the existence of Lipschitz-in-space optimal controls for a class of mean-field control problems with dynamics given by a non-local continuity equation. The proof relies on a vanishing viscosity method: we prove the convergence of…

Optimization and Control · Mathematics 2023-04-28 Gennaro Ciampa , Francesco Rossi

This paper deals with the investigation of the solution of an unified fractional reaction-diffusion equation of distributed order associated with the Caputo derivatives as the time-derivative and Riesz-Feller fractional derivative as the…

Mathematical Physics · Physics 2014-09-09 R. K. Saxena , A. M. Mathai , H. J. Haubold

Shadow systems are an approximation of reaction-diffusion-type problems obtained in the infinite diffusion coefficient limit. They allow reducing complexity of the system and hence facilitate its analysis. The quality of approximation can…

Analysis of PDEs · Mathematics 2023-08-02 Chris Kowall , Anna Marciniak-Czochra , Andro Mikelić

We consider optimal control of fractional in time (subdiffusive, i.e., for $% 0<\gamma <1$) semilinear parabolic PDEs associated with various notions of diffusion operators in an unifying fashion. Under general assumptions on the…

Optimization and Control · Mathematics 2021-10-08 Harbir Antil , Ciprian G. Gal , Mahamadi Warma

We consider optimal control problems for diffusion processes, where the objective functional is defined by a time-consistent dynamic risk measure. We focus on coherent risk measures defined by $g$-evaluations. For such problems, we…

Optimization and Control · Mathematics 2016-08-22 Andrzej Ruszczynski , Jianing Yao

In this paper, a space-time discontinuous Galerkin finite element method for distributed optimal control problems governed by unsteady diffusion-convection-reaction equations with control constraints is studied. Time discretization is…

Optimization and Control · Mathematics 2013-08-09 Tuğba Akman , Bülent Karasözen

Score-based diffusion models have demonstrated outstanding empirical performance in machine learning and artificial intelligence, particularly in generating high-quality new samples from complex probability distributions. Improving the…

Machine Learning · Statistics 2025-05-30 Yuchen Jiao , Gen Li

Diffusion models, which employ stochastic differential equations to sample images through integrals, have emerged as a dominant class of generative models. However, the rationality of the diffusion process itself receives limited attention,…

Computer Vision and Pattern Recognition · Computer Science 2024-12-17 Zhantao Yang , Ruili Feng , Han Zhang , Yujun Shen , Kai Zhu , Lianghua Huang , Yifei Zhang , Yu Liu , Deli Zhao , Jingren Zhou , Fan Cheng