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For a Keller-Segel model for chemotaxis in two spatial dimensions we consider a modification of a positivity preserving fully discrete scheme using a local extremum diminishing flux limiter. We discretize space using piecewise linear finite…

Numerical Analysis · Mathematics 2026-02-20 Panagiotis Chatzipantelidis , Christos Pervolianakis

Diffusion models have emerged as state-of-the-art generative models for image generation. However, sampling from diffusion models is usually time-consuming due to the inherent autoregressive nature of their sampling process. In this work,…

Machine Learning · Computer Science 2024-05-28 Zhiwei Tang , Jiasheng Tang , Hao Luo , Fan Wang , Tsung-Hui Chang

In this article we consider the estimation of static parameters for partially observed diffusion processes with discrete-time observations over a fixed time interval. In particular, when one only has access to time-discretized solutions of…

Methodology · Statistics 2025-09-26 Miguel Alvarez , Ajay Jasra

This paper solves a Bayes sequential impulse control problem for a diffusion, whose drift has an unobservable parameter with a change point. The partially-observed problem is reformulated into one with full observations, via a change of…

Optimization and Control · Mathematics 2014-08-19 Lokman A. Abbas-Turki , Ioannis Karatzas , Qinghua Li

In this paper, we discuss the steady and time-dependent nonlinear convection-diffusion (advection-diffusion) equations with the Dirichlet boundary condition. For the steady nonlinear equation, we use an iteration method to reformulate the…

Numerical Analysis · Mathematics 2025-07-28 Qiwei Feng , Catalin Trenchea

Diffusion models, which convert noise into new data instances by learning to reverse a diffusion process, have become a cornerstone in contemporary generative modeling. In this work, we develop non-asymptotic convergence theory for a…

Machine Learning · Computer Science 2024-08-06 Gen Li , Yuting Wei , Yuejie Chi , Yuxin Chen

The one-dimensional triplet contact process with diffusion (TCPD) model has been studied using fast multispin GPU Monte Carlo simulations. In particular, the particle density \rho and the density of pairs of neighboring particles \rho_p…

Statistical Mechanics · Physics 2015-06-15 Raoul D. Schram , Gerard T. Barkema

Transition path theory (TPT) for diffusion processes is a framework for analysing the transitions of multiscale ergodic diffusion processes between disjoint metastable subsets of state space. Most methods for applying TPT involve the…

Numerical Analysis · Mathematics 2021-03-31 Nada Cvetković , Tim Conrad , Han Cheng Lie

By means of a unifying measure-theoretic approach, we establish lower bounds on the Hausdorff dimension of the space-time set which can support anomalous dissipation for weak solutions of fluid equations, both in the presence or absence of…

Analysis of PDEs · Mathematics 2024-07-29 Luigi De Rosa , Theodore D. Drivas , Marco Inversi

This paper is concerned with $3$-D stochastic Euler-Poisson equations with insulating boundary conditions forced by the Wiener process. We first establish the global existence and uniqueness of the solution to the system, then we prove that…

Analysis of PDEs · Mathematics 2025-02-18 Yachun Li , Ming Mei , Lizhen Zhang

Diffusion models perform remarkably well on high-dimensional data such as images, often using only a modest number of reverse-time steps. Despite this practical success, existing convergence theory does not fully explain why such samplers…

Machine Learning · Computer Science 2026-05-11 Ahmad Aghapour , Erhan Bayraktar

Diffusion models, emerging as powerful deep generative tools, excel in various applications. They operate through a two-steps process: introducing noise into training samples and then employing a model to convert random noise into new…

Computer Vision and Pattern Recognition · Computer Science 2026-02-13 Huijie Zhang , Yifu Lu , Ismail Alkhouri , Saiprasad Ravishankar , Dogyoon Song , Qing Qu

We derive expressions for the first three moments of the decision time (DT) distribution produced via first threshold crossings by sample paths of a drift-diffusion equation. The "pure" and "extended" diffusion processes are widely used to…

Neurons and Cognition · Quantitative Biology 2016-01-26 Vaibhav Srivastava , Philip Holmes , Patrick Simen

We prove an averaging principle which asserts convergence of diffusion processes on domains separated by semi-permeable membranes, when diffusion coefficients tend to infinity while the flux through the membranes remains constant. In the…

Functional Analysis · Mathematics 2019-08-08 Adam Bobrowski , Bogdan Kazmierczak , Markus Kunze

A finite difference method is constructed to solve singularly perturbed convection-diffusion problems posed on smooth domains. Constraints are imposed on the data so that only regular exponential boundary layers appear in the solution. A…

Numerical Analysis · Mathematics 2021-12-23 Alan F. Hegarty , Eugene O'Riordan

We present an improved method for computing incompressible viscous flow around suspended rigid particles using a fixed and uniform computational grid. The main idea is to incorporate Peskin's regularized delta function approach [Acta…

Fluid Dynamics · Physics 2018-09-24 Markus Uhlmann

In the present work, the Eulerian Large Eddy Simulation of dilute disperse phase flows is investigated. By highlighting the main advantages and drawbacks of the available approaches in the literature, a choice is made in terms of modelling:…

Numerical Analysis · Mathematics 2015-08-21 Christophe Chalons , Marc Massot , Aymeric Vié

Using a continuum bead-spring Monte Carlo model, we study the anomalous diffusion dynamics of a self-avoiding tethered membrane by means of extensive computer simulations. We focus on the subdiffusive stochastic motion of the membrane's…

Soft Condensed Matter · Physics 2008-05-14 Hristina Popova , Andrey Milchev

Motivated by the normal form of a fast-slow ordinary differential equation exhibiting a pitchfork singularity we consider the discrete-time dynamical system that is obtained by an application of the explicit Euler method. Tracking…

Dynamical Systems · Mathematics 2019-11-22 Luca Arcidiacono , Maximilian Engel , Christian Kuehn

The document describes a numerical algorithm to simulate plasmas and fluids in the 3 dimensional space by the Euler method, in which the spatial meshes are fixed to the space. The plasmas and fluids move through the spacial Euler mesh…

Plasma Physics · Physics 2020-04-09 Hiroki Nakamura , Shigeo Kawata , Ken Uchibori , Takahiro Karino