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Diffusive transport in many complex systems features a crossover between anomalous diffusion at short times and normal diffusion at long times. This behavior can be mathematically modeled by cutting off (tempering) beyond a mesoscopic…

Statistical Mechanics · Physics 2021-10-15 Thomas Vojta , Zachary Miller , Samuel Halladay

Anomalous transport is usually described either by models of continuous time random walks (CTRW) or, otherwise by fractional Fokker-Planck equations (FFPE). The asymptotic relation between properly scaled CTRW and fractional diffusion…

Statistical Mechanics · Physics 2010-12-09 Bartlomiej Dybiec , Ewa Gudowska-Nowak

In this paper we investigate the porous medium equation with a fractional temporal derivative. We justify that the resulting equation emerges when we consider the waiting-time (or trapping) phenomenon that can happen in the medium. Our…

Analysis of PDEs · Mathematics 2015-05-20 Łukasz Płociniczak

Fractional diffusion and Fokker-Planck equations are widely used tools to describe anomalous diffusion in a large variety of complex systems. The equivalent formulations in terms of Caputo or Riemann-Liouville fractional derivatives can be…

Statistical Mechanics · Physics 2023-08-17 Qing Wei , Wei Wang , Hongwei Zhou , Ralf Metzler , Aleksei Chechkin

Continuous time random walks (CTRWs) are used in physics to model anomalous diffusion, by incorporating a random waiting time between particle jumps. In finance, the particle jumps are log-returns and the waiting times measure delay between…

Data Analysis, Statistics and Probability · Physics 2008-12-10 Mark M. Meerschaert , Enrico Scalas

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

This paper provides a finite difference discretization for the backward Feynman-Kac equation, governing the distribution of functionals of the path for a particle undergoing both reaction and diffusion [Hou and Deng, J. Phys. A: Math.…

Numerical Analysis · Mathematics 2019-11-01 Daxin Nie , Jing Sun , Weihua Deng

The prime aim of the present paper is to continue developing the theory of tempered fractional integrals and derivatives of a function with respect to another function. This theory combines the tempered fractional calculus with the…

Classical Analysis and ODEs · Mathematics 2022-11-23 Ashwini D. Mali , Kishor D. Kucche , Arran Fernandez , Hafiz Muhammad Fahad

L\'{e}vy flight models whose jumps have infinite moments are mathematically used to describe the superdiffusion in complex systems. Exponentially tempering the Levy measure of L\'{e}vy flights leads to the tempered stable L\'{e}vy processes…

Computational Physics · Physics 2016-05-19 Can Li , Weihua Deng

In this work, we consider a time-fractional Allen-Cahn equation, where the conventional first order time derivative is replaced by a Caputo fractional derivative with order $\alpha\in(0,1)$. First, the well-posedness and (limited) smoothing…

Numerical Analysis · Mathematics 2019-06-18 Qiang Du , Jiang Yang , Zhi Zhou

In the renewal processes, if the waiting time probability density function is a tempered power-law distribution, then the process displays a transition dynamics; and the transition time depends on the parameter $\lambda$ of the exponential…

Statistics Theory · Mathematics 2016-06-21 Weihua Deng , Wanli Wang , Xinchun Tian , Yujiang Wu

In this work, we investigate a variational formulation for a time-fractional Fokker-Planck equation which arises in the study of complex physical systems involving anomalously slow diffusion. The model involves a fractional-order Caputo…

Numerical Analysis · Mathematics 2020-06-05 Manh Hong Duong , Bangti Jin

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

The purpose is to study the Cauchy problem for non-linear in time and space pseudo-differential equations. These include the fractional in time versions of HJB equations governing the controlled scaled CTRW. As a preliminary step which is…

Analysis of PDEs · Mathematics 2014-02-28 V. Kolokoltsov , M. Veretennikova

Power-law probability density function (PDF) plays a key role in both subdiffusion and L\'{e}vy flights. However, sometimes because of the finite of the lifespan of the particles or the boundedness of the physical space, tempered power-law…

Numerical Analysis · Mathematics 2016-11-08 Yanyan Yu , Weihua Deng , Yujiang Wu , Jing Wu

In this paper continuous time random walk models approximating fractional space-time diffusion processes are studied. Stochastic processes associated with the considered equations represent time-changed processes, where the time-change…

Probability · Mathematics 2014-09-16 Sabir Umarov

A novel efficient and high accuracy numerical method for the time-fractional differential equations (TFDEs) is proposed in this work. We show the equivalence between TFDEs and the integer-order extended parametric differential equations…

Numerical Analysis · Mathematics 2025-05-13 Peng Ding , Zhiping Mao

The fractional Fokker-Planck system with multiple internal states is derived in [Xu and Deng, Math. Model. Nat. Phenom., $\mathbf{13}$, 10 (2018)], where the space derivative is Laplace operator. If the jump length distribution of the…

Numerical Analysis · Mathematics 2024-09-23 Daxin Nie , Jing Sun , Weihua Deng

We present a theoretical investigation of the stochastic dynamics of a damped particle in a tilted periodic potential with a double well per period. By applying the matrix continued fraction technique to the Fokker-Planck equation in…

Statistical Mechanics · Physics 2024-08-15 Martin Žonda , Wolfgang Belzig , Edward Goldobin , Tomáš Novotný

Several classes of physical systems exhibit ultraslow diffusion for which the mean squared displacement at long times grows as a power of the logarithm of time ("strong anomaly") and share the interesting property that the probability…

Statistical Mechanics · Physics 2009-11-10 A. V. Chechkin , J. Klafter , I. M. Sokolov