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Equation for anomalous diffusion in momentum space, recently obtained in the recent paper (S.A. Trigger, ArXiv 0907.2793 v1, [cond-matt. stat.-mech.], 16 July 2009) is solved for the stationary and non-stationary cases on basis of the…

Statistical Mechanics · Physics 2009-09-08 S. A. Trigger

The paper presents a general strategy to solve ordinary differential equations (ODE), where some coefficient depend on the spatial variable and on additional random variables. The approach is based on the application of a recently developed…

Numerical Analysis · Mathematics 2019-07-17 Maximilian Bochmann , Lutz Kämmerer , Daniel Potts

In this paper diffusion processes with changing modes are studied involving the variable order partial differential equations. We prove the existence and uniqueness theorem of a solution of the Cauchy problem for fractional variable order…

Mathematical Physics · Physics 2009-03-17 Sabir Umarov , Stanly Steinberg

A novel symmetry method for finding exact solutions to nonlinear PDEs is illustrated by applying it to a semilinear reaction-diffusion equation in multi-dimensions. The method uses a separation ansatz to solve an equivalent first-order…

Mathematical Physics · Physics 2013-08-05 Stephen C. Anco , Sajid Ali , Thomas Wolf

Reaction-diffusion equations (RDEs) are often derived as continuum limits of lattice-based discrete models. Recently, a discrete model which allows the rates of movement, proliferation and death to depend upon whether the agents are…

Dynamical Systems · Mathematics 2021-05-19 Yifei Li , Peter van Heijster , Matthew J. Simpson , Martin Wechselberger

This work presents a physics-conditioned latent diffusion model tailored for dynamical downscaling of atmospheric data, with a focus on reconstructing high-resolution 2-m temperature fields. Building upon a pre-existing diffusion…

Machine Learning · Computer Science 2025-10-29 Paul Rosu , Muchang Bahng , Erick Jiang , Rico Zhu , Vahid Tarokh

We present a concise, self-contained derivation of diffusion-based generative models. Starting from basic properties of Gaussian distributions (densities, quadratic expectations, re-parameterisation, products, and KL divergences), we…

Machine Learning · Computer Science 2025-11-18 Sepehr Maleki , Negar Pourmoazemi

We present our deep learning framework to solve and accelerate the Time-Dependent partial differential equation's solution of one and two spatial dimensions. We demonstrate DiffusionNet solver by solving the 2D transient heat conduction…

Machine Learning · Computer Science 2020-11-20 Mahmoud Asem

The time-fractional diffusion equation is considered, where the time derivative is either of Caputo or Riemann-Liouville type. The solution of a general initial-boundary value problem with time-dependent boundary conditions over bounded and…

Analysis of PDEs · Mathematics 2023-01-04 M. Rodrigo

A {\em propagation-dispersion equation} is derived for the first passage distribution function of a particle moving on a substrate with time delays. The equation is obtained as the continuous limit of the {\em first visit equation}, an…

Statistical Mechanics · Physics 2007-05-23 Jean Pierre Boon , Patrick Grosfils , James F. Lutsko

We consider similarity solutions of the generalized convection-diffusion-reaction equation with both space- and time-dependent convection, diffusion and reaction terms. By introducing the similarity variable, the reaction-diffusion equation…

Mathematical Physics · Physics 2019-05-01 C. -L. Ho , C. -M. Yang

This paper derives the Fokker-Planck (FP) equation for a particle moving in potential by a randomly modulated dipole. The FP equation describes the anomalous diffusion observed in the companion paper [1] and breaks the conservation of the…

Mathematical Physics · Physics 2022-05-03 S. Katagiri , Y. Matsuo , Y. Matsuoka , A. Sugamoto

We propose certain approach of solving two-dimensional non-stationary and stationary advection-diffusion-reaction boundary value problems through their reduction to the set of corresponding one-dimensional problems. This method leverages…

Numerical Analysis · Mathematics 2024-11-19 R. Drebotiy , H. Shynkarenko

We present several analytical approaches to the Dicke superradiance problem, which involves determining the time evolution of the density operator for an initially inverted ensemble of $N$ identical two-level systems undergoing collective…

In this paper, the one-dimensional time-fractional diffusion-wave equation with the fractional derivative of order $1 \le \alpha \le 2$ is revisited. This equation interpolates between the diffusion and the wave equations that behave quite…

Mathematical Physics · Physics 2016-01-14 Yuri Luchko , Francesco Mainardi , Yuriy Povstenko

Fractional diffusion equations replace the integer-order derivatives in space and time by their fractional-order analogues. They are used in physics to model anomalous diffusion. This paper develops strong solutions of space-time fractional…

Probability · Mathematics 2016-12-19 Zhen-Qing Chen , Mark M. Meerschaert , Erkan Nane

Self-diffusion in a two-dimensional simple fluid is investigated by both analytical and numerical means. We investigate the anomalous aspects of self-diffusion in two-dimensional fluids with regards to the mean square displacement, the…

Soft Condensed Matter · Physics 2018-09-05 Bongsik Choi , Kyeong Hwan Han , Changho Kim , Peter Talkner , Akinori Kidera , Eok Kyun Lee

We investigate the fractional diffusion approximation of a kinetic equation set in a bounded interval with diffusive reflection conditions at the boundary. In an appropriate singular limit corresponding to small Knudsen number and long time…

Analysis of PDEs · Mathematics 2021-07-05 Ludovic Cesbron , Antoine Mellet , Marjolaine Puel

We study the diffusion (or heat) equation on a finite 1-dimensional spatial domain, but we replace one of the boundary conditions with a "nonlocal condition", through which we specify a weighted average of the solution over the spatial…

Analysis of PDEs · Mathematics 2017-08-04 Peter D. Miller , David A. Smith

In this paper, we investigated a density-dependent reaction-diffusion equation, $u_t = (u^{m})_{xx} + u - u^{m}$. This equation is known as the extension of the Fisher or Kolmogoroff-Petrovsky-Piscounoff equation which is widely used in the…

Biological Physics · Physics 2012-06-19 Waipot Ngamsaad , Kannika Khompurngson