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The continuous-time random walk (CTRW) model is useful for alleviating the computational burden of simulating diffusion in actual media. In principle, isotropic CTRW only requires knowledge of the step-size, $P_l$, and waiting-time, $P_t$,…

Statistical Mechanics · Physics 2017-01-19 Shahar Amitai , Raphael Blumenfeld

Continuous-time random walks are generalisations of random walks frequently used to account for the consistent observations that many molecules in living cells undergo anomalous diffusion, i.e. subdiffusion. Here, we describe the…

Analysis of PDEs · Mathematics 2015-03-31 Hugues Berry , Thomas Lepoutre , Álvaro Mateos González

Modelling random dynamical systems in continuous time, diffusion processes are a powerful tool in many areas of science. Model parameters can be estimated from time-discretely observed processes using Markov chain Monte Carlo (MCMC) methods…

Computation · Statistics 2020-10-12 Susanne Pieschner , Christiane Fuchs

In this paper a Monte-Carlo method for simulating the motion of fluid flow moving along a solid wall is proposed. The random vortex method in the present paper is established by using the reflection technology and perturbation technique.…

Fluid Dynamics · Physics 2022-08-30 Z. Qian , Y. Qiu , L. Zhao , J. Wu

Discrete-time quantum walks, quantum generalizations of classical random walks, provide a framework for quantum information processing, quantum algorithms and quantum simulation of condensed matter systems. The key property of quantum…

Quantum Physics · Physics 2023-06-07 Rostislav Duda , Moein N. Ivaki , Isac Sahlberg , Kim Pöyhönen , Teemu Ojanen

Transport and acceleration of charged particles in turbulent media is a topic of great interest in space physics and interstellar astrophysics. These processes are dominated by the scattering of particles off magnetic irregularities. The…

Space Physics · Physics 2016-12-28 A. Ivascenko , S. Lange , F. Spanier , R. Vainio

Random diffusions are a popular tool in Monte-Carlo estimations, with well established algorithms such as Walk-on-Spheres (WoS) going back several decades. In this work, we introduce diffusion estimators for the problems of angular…

Probability · Mathematics 2024-10-15 Hugo Jaquard , Pierre-Olivier Amblard , Simon Barthelmé , Nicolas Tremblay

In this paper we study the asymptotic behavior of the Random-Walk Metropolis algorithm on probability densities with two different `scales', where most of the probability mass is distributed along certain key directions with the…

Computation · Statistics 2015-10-12 Alexandros Beskos , Gareth Roberts , Alexandre Thiery , Natesh Pillai

Background: This study is mainly motivated by the need of understanding how the diffusion behaviour of a biomolecule (or even of a larger object) is affected by other moving macromolecules, organelles, and so on, inside a living cell,…

Biological Physics · Physics 2016-01-15 Matteo Gori , Irene Donato , Elena Floriani , Ilaria Nardecchia , Marco Pettini

Random walks are ubiquitous in the sciences, and they are interesting from both theoretical and practical perspectives. They are one of the most fundamental types of stochastic processes; can be used to model numerous phenomena, including…

Physics and Society · Physics 2020-04-13 Naoki Masuda , Mason A. Porter , Renaud Lambiotte

Reflected diffusions in polyhedral domains are commonly used as approximate models for stochastic processing networks in heavy traffic. Stationary distributions of such models give useful information on the steady state performance of the…

Probability · Mathematics 2012-05-24 Amarjit Budhiraja , Jiang Chen , Sylvain Rubenthaler

The foundations of the fractional diffusion equation are investigated based on coupled and decoupled continuous time random walks (CTRW). For this aim we find an exact solution of the decoupled CTRW, in terms of an infinite sum of stable…

Statistical Mechanics · Physics 2009-11-07 Eli Barkai

We consider a random walk model in a one-dimensional environment, formed by several zones of finite width with the fixed transition probabilities. It is also assumed that the transitions to the left and right neighboring points have unequal…

Statistical Mechanics · Physics 2017-08-18 A. V. Nazarenko , V. Blavatska

Recent advances in machine learning have led to the development of new methods for enhancing Monte Carlo methods such as Markov chain Monte Carlo (MCMC) and importance sampling (IS). One such method is normalizing flows, which use a neural…

Computation · Statistics 2024-01-12 Charly Andral

Importance sampling is a widely used technique to reduce the variance of a Monte Carlo estimator by an appropriate change of measure. In this work, we study importance sam- pling in the framework of diffusion process and consider the change…

Probability · Mathematics 2018-03-28 Carsten Hartmann , Christof Schütte , Marcus Weber , Wei Zhang

Aims. Numerical test-particle simulations are a reliable and frequently used tool to test analytical transport theories and to predict mean-free paths. The comparison between solutions of the diffusion equation and the particle flux is used…

High Energy Astrophysical Phenomena · Physics 2016-02-17 R. C. Tautz , J. Bolte , A. Shalchi

A variation of Rosenstock's trapping model in which $N$ independent random walkers are all initially placed upon a site of a one-dimensional lattice in the presence of a {\em one-sided} random distribution (with probability $c$) of…

Statistical Mechanics · Physics 2015-06-24 S. B. Yuste , L. Acedo

X-ray dose constantly gains interest in the interventional suite. With dose being generally difficult to monitor reliably, fast computational methods are desirable. A major drawback of the gold standard based on Monte Carlo (MC) methods is…

Graph generation addresses the problem of generating new graphs that have a data distribution similar to real-world graphs. While previous diffusion-based graph generation methods have shown promising results, they often struggle to scale…

Machine Learning · Computer Science 2025-05-28 Tobias Bernecker , Ghalia Rehawi , Francesco Paolo Casale , Janine Knauer-Arloth , Annalisa Marsico

We present a numerical method and computer code to calculate the radiative transfer and excitation of molecular lines. Formulating the Monte Carlo method from the viewpoint of cells rather than photons allows us to separate local and…

Astrophysics · Physics 2007-05-23 Michiel R. Hogerheijde , Floris F. S. van der Tak