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The formulation of combinatorial differential forms, proposed by Forman for analysis of topological properties of discrete complexes, is extended by defining the operators required for analysis of physical processes dependent on scalar…

Mathematical Physics · Physics 2026-05-22 Kiprian Berbatov , Pieter D. Boom , Andrew L. Hazel , Andrey P. Jivkov

The statistical analysis of covariance matrix data is considered and, in particular, methodology is discussed which takes into account the non-Euclidean nature of the space of positive semi-definite symmetric matrices. The main motivation…

Applications · Statistics 2009-10-12 Ian L. Dryden , Alexey Koloydenko , Diwei Zhou

A gas or vapor bubble collapsing in the vicinity of a rigid boundary displaces towards the boundary and produces a high-speed jet directed at the boundary. This behavior has been shown to be a function of the 'anisotropy' of the collapse,…

Fluid Dynamics · Physics 2022-11-16 Elijah D. Andrews , Ivo R. Peters

Anomalous-diffusion, the departure of the spreading dynamics of diffusing particles from the traditional law of Brownian-motion, is a signature feature of a large number of complex soft-matter and biological systems. Anomalous-diffusion…

We analyze DAMPE and H.E.S.S. measurements of the total cosmic-ray electron-positron spectrum, together with the AMS-02 positron fraction, using an anisotropic, spatially varying diffusion framework. The diffusion-tensor components are…

High Energy Astrophysical Phenomena · Physics 2026-04-27 V. D. Borisov , I. A. Kudryashov

Propagation of gamma-beam in the anisotropic medium is considered. The simpliest example of such a medium of the general type is a combination of the two linearly polarized monochromatic laser waves with different frequencies (dichromatic…

High Energy Physics - Phenomenology · Physics 2007-05-23 V. A. Maisheev

Under low-Reynolds-number conditions, dynamics of convection and diffusion are usually considered separately because their dominant spatial and temporal scales are different, but cooperative effects of convection and diffusion can cause…

Fluid Dynamics · Physics 2022-08-04 Yuki Koyano , Hiroyuki Kitahata

We investigate the ensemble and time averaged mean squared displacements for particle diffusion in a simple model for disordered media by assuming that the local diffusivity is both fluctuating in time and has a deterministic average growth…

Statistical Mechanics · Physics 2016-10-05 A. G. Cherstvy , R. Metzler

We highlight a few recent results on the effect of the diffusion process in deterministic area preserving maps with noncompact phase space, namely the standard map. In more detail, we focus on the anomalous diffusion arising due to the…

Chaotic Dynamics · Physics 2015-01-09 T. Manos , M. Robnik

We consider a spatially homogeneous advection-diffusion equation in which the diffusion tensor and drift velocity are time-independent, but otherwise general. We derive asymptotic expressions, valid at large distances from a steady point…

Chaotic Dynamics · Physics 2015-05-20 John Grant , Michael Wilkinson

Low-dimensional periodic arrays of scatterers with a moving point particle are ideal models for studying deterministic diffusion. For such systems the diffusion coefficient is typically an irregular function under variation of a control…

Chaotic Dynamics · Physics 2009-11-07 R. Klages , N. Korabel

The time dependency of the diffusion coefficient of particles in porous media is an efficient probe of their geometry. The analysis of this quantity, measured e.g. by nuclear magnetic resonance (PGSE-NMR), can provide rich information…

Soft Condensed Matter · Physics 2013-02-13 Maximilien Levesque , Olivier Bénichou , Benjamin Rotenberg

We study photon diffusion in a two-dimensional random packing of monodisperse disks as a simple model of granular material. We apply ray optics approximation to set up a persistent random walk for the photons. We employ Fresnel's intensity…

Optics · Physics 2012-03-20 Zeinab Sadjadi , MirFaez Miri

We study a simple model of a random walker in d dimensions moving in the presence of a local heterogeneous attracting factor expressed in terms of an assigned space-dependent "attractiveness function", a situation frequently encountered in…

Statistical Mechanics · Physics 2017-06-21 Hardi Veermäe , Marco Patriarca

Dispersion experiments are compared for two transparent model fractures with identical complementary rough walls but with a relative shear displacement $\vec{\delta}$ parallel ($\vec{\delta}\parallel \vec{U}$) or perpendicular…

We consider a diffusion on a bounded domain, assuming that the system is irreducible inside the domain and that the diffusion has varying degree of degeneracy on the domain's boundary. The long-term statistical properties of typical…

Probability · Mathematics 2025-08-29 Yuri Bakhtin , Renaud Raquépas , Lai-Sang Young

Often, the unknown diffusivity in diffusive processes is structured by piecewise constant patches. This paper is devoted to efficient methods for the determination of such structured diffusion parameters by exploiting shape calculus. A…

Optimization and Control · Mathematics 2021-04-12 Volker Schulz , Martin Siebenborn , Kathrin Welker

We study the random walk of a particle in a compartmentalized environment, as realized in biological samples or solid state compounds. Each compartment is characterized by its length $L$ and the boundaries transmittance $T$. We identify two…

Statistical Mechanics · Physics 2019-03-12 Gorka Muñoz-Gil , Miguel Angel García-March , Carlo Manzo , Alessio Celi , Maciej Lewenstein

In this article, we study the spreading of droplets of density-matched granular suspensions on the surface of a solid. Bidispersity of the particle size distribution enriches the conclusions drawn from monodisperse experiments by…

Soft Condensed Matter · Physics 2023-01-25 Alice Pelosse , Élisabeth Guazzelli , Matthieu Roché

We show that a unified and maximally generalized approach to spatial transformation design is possible, one that encompasses all second order waves, rays, and diffusion processes in anisotropic media. Until the final step, it is unnecessary…

Classical Physics · Physics 2018-05-04 Paul Kinsler , Martin W. McCall