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Using a so-called hemispherical model we derive a general transport equation for cosmic ray and thermal particles scattered in pitch angle by magnetic inhomogeneities in a moving collisionless plasma. The weak scattering through 90 degrees…

Astrophysics · Physics 2009-11-11 V. N. Zirakashvili

We develop a self-consistent theoretical formalism to model the dynamics of heat transfer in dissipative, dispersive, anisotropic nanoscale media, such as metamaterials. We employ our envelope dyadic Green's function method to solve…

Classical Physics · Physics 2024-11-19 Hodjat Mariji , Stanislav Maslovski

A new approach to the modeling of nonfree particle diffusion is presented. The approach uses a general setup based on geometric graphs (networks of curves), which means that particle diffusion in anything from arrays of barriers and pore…

Statistical Mechanics · Physics 2018-04-05 Niels Buhl

In this letter, we propose a reduced-order model to bridge the particle transport mechanics and the macroscopic fluid dynamics in the highly scattered regime. A rigorous mathematical derivation and a concise physical interpretation are…

Mathematical Physics · Physics 2023-09-22 Yuan Hu , Chang Liu , Huayun Shen

Dynamic modulation of material properties in space and time enables powerful control over wave propagation, yet existing theories largely rely on idealized, nondispersive models. In realistic media, frequency dispersion can strongly reshape…

Optics · Physics 2026-04-02 Klaas De Kinder , Christophe Caloz

Diffusion models are a class of generative models that serve to establish a stochastic transport map between an empirically observed, yet unknown, target distribution and a known prior. Despite their remarkable success in real-world…

Machine Learning · Computer Science 2025-03-13 Puheng Li , Zhong Li , Huishuai Zhang , Jiang Bian

The subject matter of this paper concerns anisotropic diffusion equations: we consider heat equations whose diffusion matrix have disparate eigenvalues. We determine first and second order approximations, we study the well-posedness of them…

Analysis of PDEs · Mathematics 2012-10-24 Mihai Bostan

We assess the impact of radiation anisotropy on the line shapes that result from relativistic magnetic Compton scattering in the low-density/high-field regime. A Monte Carlo implementation of radiation transport allows for spatial diffusion…

Astrophysics · Physics 2009-10-31 Rafael A. Araya-Gochez , Alice K. Harding

We solve the radiative transfer equation (RTE) in anisotropically scattering media as an infinite series. Each series term represents a distinct number of scattering events, with analytical solutions derived for zero and single scattering.…

High Energy Physics - Phenomenology · Physics 2024-07-25 Vladimir Allakhverdian , Dmitry V. Naumov

A theory of cosmic-ray transport in multi-phase diffusive media is developed, with the specific application to cases in which the cosmic-ray diffusion coefficient has large spatial fluctuations that may be inherently multi-scale. We…

The difficulty of description of the radiative transfer in disordered photonic crystals arises from the necessity to consider on the equal footing the wave scattering by periodic modulations of the dielectric function and by its random…

Disordered Systems and Neural Networks · Physics 2009-10-16 M. V. Erementchouk , L. I. Deych , H. Noh , H. Cao , A. A. Lisyansky

Rosenfeld [Phys. Rev. A 15, 2545 (1977)] noticed that casting transport coefficients of simple monatomic, equilibrium fluids in specific dimensionless forms makes them approximately single-valued functions of excess entropy. This has…

The Markovian diffusion theory in the phase space is generalized within the framework of the general theory of relativity. The introduction of moving orthonormal frame vectors both for the position as well the velocity space enables to…

General Relativity and Quantum Cosmology · Physics 2014-11-20 Joachim Herrmann

Within the scattering matrix approach to electronic transport, the scattering and transport properties of tight-binding random graphs are analyzed. In particular, we compute the scattering matrix elements, the transmission, the…

Disordered Systems and Neural Networks · Physics 2023-10-09 A. M. Martínez-Argüello , K. B. Hidalgo-Castro , J. A. Méndez-Bermúdez

Cosmic rays (CR), constrained by scattering on magnetic irregularities, are believed to propagate diffusively. But a well-known defect of diffusive approximation whereby some of the particles propagate unrealistically fast has directed…

High Energy Astrophysical Phenomena · Physics 2016-10-11 Mikhail Malkov , Roald Sagdeev

Statistical properties of coherent radiation propagating in a quasi - 1D random media is studied in the framework of random matrix theory. Distribution functions for the total transmission coefficient and the angular transmission…

Condensed Matter · Physics 2009-10-28 Eugene Kogan , Moshe Kaveh

We consider in a two dimensional absorbing and scattering medium, an inverse source problem in the stationary radiative transport, where the source is linearly anisotropic. The medium has an anisotropic scattering property that is neither…

Analysis of PDEs · Mathematics 2022-11-02 David Omogbhe , Kamran Sadiq

We carry out a general study on the collapse of axially (and reflection) symmetric sources in the context of general relativity. All basic equations and concepts required to perform such a general study are deployed. These equations are…

General Relativity and Quantum Cosmology · Physics 2015-06-19 L. Herrera , A. Di Prisco , J. Ibañez , J. Ospino

The objective of this article is to highlight certain features of a number of coefficients that appear in models of phenomena of transport in anisotropic porous media, especially the coefficient of dispersion, the 2nd rank tensor D_{ij},…

Fluid Dynamics · Physics 2009-05-12 Jacob Bear , Leonid G. Fel , Yoram Zimmels

We revisit the inverse source problem in a two dimensional absorbing and scattering medium and present a non-iterative reconstruction method using measurements of the radiating flux at the boundary. The attenuation and scattering…

Analysis of PDEs · Mathematics 2020-01-29 Hiroshi Fujiwara , Kamran Sadiq , Alexandru Tamasan