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In this article we study inverse source problems for time-fractional diffusion equations from \textit{a posteriori} boundary measurement. Using the memory effect of these class of equations, we solve these inverse problems for several class…

Analysis of PDEs · Mathematics 2022-07-15 Jaan Janno , Yavar Kian

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

Fractional, anomalous diffusion in space-periodic potentials is investigated. The analytical solution for the effective, fractional diffusion coefficient in an arbitrary periodic potential is obtained in closed form in terms of two…

Statistical Mechanics · Physics 2021-02-02 E. Heinsalu , M. Patriarca , I. Goychuk , P. Hanggi

Uchaikin suggested a mathematical model of an anomalous diffusion in a space was suggested. This model origins in an investigation of processes in complex systems with variable structure: glasses, liquid crystals, biopolymers, proteins and…

Probability · Mathematics 2007-05-23 G. Sh. Tsitsiashvili , A. E. Yashin

The silo discharge process is studied by molecular dynamics simulations. The development of the velocity profile and the probability density function for the displacements in the horizontal and vertical axis are obtained. The PDFs obtained…

Statistical Mechanics · Physics 2009-11-11 R. Arevalo , A. Garcimartin , D. Maza

Modeling of phenomena such as anomalous transport via fractional-order differential equations has been established as an effective alternative to partial differential equations, due to the inherent ability to describe large-scale behavior…

Analysis of PDEs · Mathematics 2021-10-25 Jorge Suzuki , Mamikon Gulian , Mohsen Zayernouri , Marta D'Elia

In this paper, compact finite difference schemes for the modified anomalous fractional sub-diffusion equation and fractional diffusion-wave equation are studied. Schemes proposed previously can at most achieve temporal accuracy of order…

Numerical Analysis · Mathematics 2015-06-17 Zhibo Wang , Seakweng Vong

The anomalous (i.e. non-Gaussian) dynamics of particles subject to a deterministic acceleration and a series of 'random kicks' is studied. Based on an extension of the concept of continuous time random walks to position-velocity space, a…

Statistical Mechanics · Physics 2009-11-11 R. Friedrich , F. Jenko , A. Baule , S. Eule

This article starts over the backwards diffusion problem by replacing the \emph{noncausal} diffusion equation, the direct problem, by the \emph{causal} diffusion model developed in \cite{Kow11} for the case of constant diffusion speed. For…

Analysis of PDEs · Mathematics 2013-08-05 Richard Kowar

Using diffusion priors to solve inverse problems in imaging have significantly matured over the years. In this chapter, we review the various different approaches that were proposed over the years. We categorize the approaches into the more…

Machine Learning · Computer Science 2025-08-05 Hyungjin Chung , Jeongsol Kim , Jong Chul Ye

This article proves the uniqueness for two kinds of inverse problems of identifying fractional orders in diffusion equations with multiple time-fractional derivatives by pointwise observation. By means of eigenfunction expansion and Laplace…

Analysis of PDEs · Mathematics 2019-04-15 Zhiyuan Li , Masahiro Yamamoto

The time fractional diffusion equation is obtained from the standard diffusion equation by replacing the first-order time derivative with a fractional derivative of order $\beta \in (0,1)$. The fundamental solution for the Cauchy problem is…

Mathematical Physics · Physics 2008-05-27 Francesco Mainardi , Gianni Pagnini , Rudolf Gorenflo

The motion of contaminant particles through complex environments such as fractured rocks or porous sediments is often characterized by anomalous diffusion: the spread of the transported quantity is found to grow sublinearly in time due to…

Statistical Mechanics · Physics 2009-11-13 M. Marseguerra , A. Zoia

Many inverse problems have to deal with complex, evolving and often not exactly known geometries, e.g. as domains of forward problems modeled by partial differential equations. This makes it desirable to use methods which are robust with…

Numerical Analysis · Mathematics 2015-07-13 Martin Burger , Ole Loseth Elvetun , Matthias Schlottbom

Diffusion processes are important in several physical, chemical, biological and human phenomena. Examples include molecular encounters in reactions, cellular signalling, the foraging of animals, the spread of diseases, as well as trends in…

Data Analysis, Statistics and Probability · Physics 2021-06-21 Alessia Gentili , Giorgio Volpe

Variable order space-fractional diffusion equation derived as an important model to describe complex anomalous diffusion phenomenon. In this article, well-posedness theory has been constructed for equations with the "Dirichlet" or the…

Analysis of PDEs · Mathematics 2016-11-08 Junxiong Jia , Jigen Peng

We propose an interpolation expression using the difference moment (Kolmogorov transient structural function) of the second order as the average characteristic of displacements for identifying the anomalous diffusion in complex processes…

Data Analysis, Statistics and Probability · Physics 2010-08-25 Serge F. Timashev , Yuriy S. Polyakov , Pavel I. Misurkin , Sergey G. Lakeev

This paper investigates an inverse source problem for space-time fractional diffusion equations from a posteriori interior measurements. The uniqueness result is established by the memory effect of fractional derivatives and the unique…

Numerical Analysis · Mathematics 2025-10-24 Kai Yu , Zhiyuan Li , Yikan Liu

Application of fractional calculus to the description of anomalous diffusion and relaxation processes in complex media provided one of the most impressive impulses to the development of statistical physics during the last decade. In…

Soft Condensed Matter · Physics 2008-11-13 A. E. Sitnitsky

We show analytically that there is anomalous diffusion when the diffusion constant depends on the concentration as a power law with a positive exponent or a negative exponent with absolute value less than one and the initial condition is a…

Statistical Mechanics · Physics 2019-12-13 Alex Hansen , Eirik G. Flekkøy