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We study invariant solutions of a certain class of time-fractional diffusion-wave equations with variable coefficients via Lie symmetry analysis. In physics, the fractional diffusion equation describes transport dynamics that are governed…

In this paper the multi-dimensional random walk models governed by distributed fractional order differential equations and multi-term fractional order differential equations are constructed. The scaling limits of these random walks to a…

Dynamical Systems · Mathematics 2007-05-23 Erik Andries , Sabir Umarov , Stanly Steinberg

We consider a general one-dimensional overdamped diffusion model described by the It\^{o} stochastic differential equation (SDE) ${dX_t=\mu(X_t,t)dt+\sigma(X_t,t)dW_t}$, where $W_t$ is the standard Wiener process. We obtain a specific…

Statistical Mechanics · Physics 2025-07-09 Costantino Di Bello , Édgar Roldán , Ralf Metzler

Diffusion has been widely used to describe a random walk of particles or waves, and it requires only one parameter -- the diffusion constant. For waves, however, diffusion is an approximation that disregards the possibility of interference.…

Optics · Physics 2014-01-23 Alexey G. Yamilov , Raktim Sarma , Brandon Redding , Ben Payne , Heeso Noh , Hui Cao

An anomalous diffusion model for ion channel gating is put forward. This scheme is able to describe non-exponential, power-law like distributions of residence time intervals in several types of ion channels. Our method presents a…

Biological Physics · Physics 2007-05-23 Igor Goychuk , Peter Hanggi

We have derived a fractional Fokker-Planck equation for subdiffusion in a general space-and- time-dependent force field from power law waiting time continuous time random walks biased by Boltzmann weights. The governing equation is derived…

Statistical Mechanics · Physics 2010-10-27 B. I. Henry , T. A. M Langlands , P. Straka

We formulate a compounded random walk that is physically well defined on both finite and infinite domains, and samples space-dependent forces throughout jumps. The governing evolution equation for the walk limits to a space-fractional…

Statistical Mechanics · Physics 2025-11-25 Christopher N. Angstmann , Daniel S. Han , Bruce I. Henry , Boris Z. Huang , Zhuang Xu

Random walk has wide applications in many fields, such as machine learning, biology, physics, and chemistry. Random walk can be discrete or continuous in time and space. Asymmetric random walk could be described by drift-diffusion equation.…

Statistical Mechanics · Physics 2024-03-01 Guoxing Lin , Shaokun Zheng

We consider a Markovian jumping process which is defined in terms of the jump-size distribution and the waiting-time distribution with a position-dependent frequency, in the diffusion limit. We assume the power-law form for the frequency.…

Statistical Mechanics · Physics 2015-07-20 T. Srokowski , A. Kaminska

We prove sharp estimates for the decay in time of solutions to a rather general class of non-local in time subdiffusion equations on a bounded domain subject to a homogeneous Dirichlet boundary condition. Important special cases are the…

Analysis of PDEs · Mathematics 2013-10-02 Vicente Vergara , Rico Zacher

Recently a new type of Kramers-Fokker-Planck Equation has been proposed [R. Friedrich et al. Phys. Rev. Lett. {\bf 96}, 230601 (2006)] describing anomalous diffusion in external potentials. In the present paper the explicit cases of a…

Statistical Mechanics · Physics 2007-05-23 S. Eule , R. Friedrich , F. Jenko

We study a scenario under which variable step random walks give anomalous statistics. We begin by analyzing the Martingale Central Limit Theorem to find a sufficient condition for the limit distribution to be non-Gaussian. We note that the…

Data Analysis, Statistics and Probability · Physics 2009-11-10 Gemunu H. Gunaratne , Joseph L. McCauley , Matthew Nicol , Andrei Torok

The uncoupled Continuous Time Random Walk (CTRW) in one space-dimension and under power law regime is splitted into three distinct random walks: (rw_1), a random walk along the line of natural time, happening in operational time; (rw_2), a…

Probability · Mathematics 2011-04-21 Rudolf Gorenflo , Francesco Mainardi

We consider a particle transport process in a one-dimensional system with a thin membrane, described by a normal diffusion equation. We consider two boundary conditions at the membrane that are linear combinations of integral operators,…

Statistical Mechanics · Physics 2022-05-24 Tadeusz Kosztołowicz , Aldona Dutkiewicz

In this work, we investigate the recovery of a parameter in a diffusion process given by the order of derivation in time for a class of diffusion type equations, including both classical and time-fractional diffusion equations, from the…

Analysis of PDEs · Mathematics 2021-11-04 Bangti Jin , Yavar Kian

The following question is addressed: under what conditions can a strange diffusive process, defined by a semi-dynamical V-Langevin equation or its associated Hybrid kinetic equation (HKE), be described by an equivalent purely stochastic…

Plasma Physics · Physics 2015-05-13 Radu Balescu

It is proved that the distributions of scaling limits of Continuous Time Random Walks (CTRWs) solve integro-differential equations akin to Fokker-Planck Equations for diffusion processes. In contrast to previous such results, it is not…

Probability · Mathematics 2016-07-20 Boris Baeumer , Peter Straka

Subdiffusion in a system in which mobile particles $A$ can chemically react with static particles $B$ according to the rule $A+B\rightarrow B$ is considered within a persistent random walk model. This model, which assumes a correlation…

Statistical Mechanics · Physics 2015-06-16 Tadeusz Kosztołowicz

Consider a particle diffusing in a confined volume which is divided into two equal regions. In one region the diffusion coefficient is twice the value of the diffusion coefficient in the other region. Will the particle spend equal…

Dynamical Systems · Mathematics 2015-06-04 P. F. Tupper , Xin Yang

A new solution to the mono-dimensional diffusion equation for time-variable first kind boundary condition is presented where the time-variable function at the surface is derived proposing a surface saturation model. This solution may be…

Materials Science · Physics 2022-12-08 Guglielmo Macrelli