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A simplified transient energy-transport system for semiconductors subject to mixed Dirichlet-Neumann boundary conditions is analyzed. The model is formally derived from the non-isothermal hydrodynamic equations in a particular vanishing…

Analysis of PDEs · Mathematics 2012-06-26 Ansgar Jüngel , René Pinnau , Elisa Röhrig

In a recent work, we presented the first application of the Poisson-Wiseman-Anderson method of `matched expansions' to compute the self-force acting on a point particle moving in a curved spacetime. The method employs two expansions for the…

General Relativity and Quantum Cosmology · Physics 2010-03-03 Barry Wardell , Adrian C. Ottewill

We investigate heat transport in a spin-1/2 Heisenberg chain, coupled locally to independent thermal baths of different temperature. The analysis is carried out within the framework of the theory of open systems by means of appropriate…

Quantum Physics · Physics 2009-11-13 Hannu Wichterich , Markus J. Henrich , Heinz-Peter Breuer , Jochen Gemmer , Mathias Michel

The transport of charged particles or photons in a scattering medium can be modelled with a Boltzmann equation. The mathematical treatment for scattering in such scenarios is often simplified if evaluated in a frame where the scattering…

Plasma Physics · Physics 2024-02-27 Nils W. Schween , Brian Reville

We develop a simple mean field approach to the transport of a passive scalar for which the fundamental equation is a second order differential equation in the transported quantity, not a first order equation. Triple correlations are…

Astrophysics · Physics 2009-11-07 Eric G. Blackman , George B. Field

Context. Spacecraft observations have motivated the need for a refined description of the phase-space distribution function. Of particular importance is the pitch-angle diffusion coefficient that occurs in the Fokker-Planck transport…

High Energy Astrophysical Phenomena · Physics 2014-10-27 R. C. Tautz , A. Dosch , F. Effenberger , H. Fichtner , A. Kopp

On the space of probability densities, we extend the Wasserstein geodesics to the case of higher-order interpolation such as cubic spline interpolation. After presenting the natural extension of cubic splines to the Wasserstein space, we…

Optimization and Control · Mathematics 2018-07-27 Jean-David Benamou , Thomas Gallouët , François-Xavier Vialard

In this paper we investigate the implementation of the so-called freezing method for second order wave equations in one and several space dimensions. The method converts the given PDE into a partial differential algebraic equation which is…

Analysis of PDEs · Mathematics 2017-04-25 Wolf-Jürgen Beyn , Denny Otten , Jens Rottmann-Matthes

This paper reviews some selected approaches to the description of transport properties, mainly electroconductivity, in crystalline and disordered metallic systems. A detailed qualitative theoretical formulation of the electron transport…

Statistical Mechanics · Physics 2011-09-27 A. L. Kuzemsky

The expansion of an initially confined Bose-Einstein condensate into either free space or a tilted optical lattice is investigated in a mean-field approach. The effect of the interactions is to enhance or suppress the transport depending on…

Quantum Gases · Physics 2017-12-29 Samy Mailoud Sekkouri , Sandro Wimberger

We consider the numerical solution of the optimal transport problem between densities that are supported on sets of unequal dimension. Recent work by McCann and Pass reformulates this problem into a non-local Monge-Amp\`ere type equation.…

Numerical Analysis · Mathematics 2023-07-14 Matthew A. Cassini , Brittany Froese Hamfeldt

A Langevin equation is proposed to describe the transport of overdamped Brownian particles in a periodic rough potential and driven by an unbiased periodic force. The equation can be transformed into the Fokker-Planck equation by using the…

Statistical Mechanics · Physics 2023-04-05 Peng Wang , Yang Zhang , Peng-Juan Zhang , Jie Huo , Xu-Ming Wang

Ion transport, often described by the Poisson--Nernst--Planck (PNP) equations, is ubiquitous in electrochemical devices and many biological processes of significance. In this work, we develop conservative, positivity-preserving, energy…

Numerical Analysis · Mathematics 2020-07-15 Jie Ding , Zhongming Wang , Shenggao Zhou

The quantum version of the Boltzmann transport equation (Wigner-Boltzmann equation) is a quite useful tool to investigate the effects of energy dissipation in quantum systems. Numerical approaches uses to be employed in order to stablish a…

Statistical Mechanics · Physics 2017-09-19 A. R. Fernandes Nt. , L. F. Santos

This is the second component of a two-part paper dealing with a unification of characteristic mode decomposition. This second part addresses modal tracking and losses and presents several numerical examples for both surface- and…

Classical Physics · Physics 2023-01-04 Mats Gustafsson , Lukas Jelinek , Kurt Schab , Miloslav Capek

The diffusion in two dimensions of non-interacting active particles that follow an arbitrary motility pattern is considered for analysis. Accordingly, the transport equation is generalized to take into account an arbitrary distribution of…

Statistical Mechanics · Physics 2020-09-01 Francisco J. Sevilla

Parallel thermal conduction along stochastic magnetic field lines may be reduced because the heat conducting electrons become trapped and detrapped between regions of strong magnetic field (magnetic mirrors). The problem reduces to a simple…

Astrophysics · Physics 2009-10-31 Leonid Malyshkin , Russell Kulsrud

This article introduces a new notion of optimal transport (OT) between tensor fields, which are measures whose values are positive semidefinite (PSD) matrices. This "quantum" formulation of OT (Q-OT) corresponds to a relaxed version of the…

Graphics · Computer Science 2017-07-25 Gabriel Peyré , Lenaïc Chizat , François-Xavier Vialard , Justin Solomon

Orbit-based methods are widespread in strong-field laser-matter interaction. They provide a framework in which photoelectron momentum distributions can be interpreted as the quantum interference between different semi-classical pathways the…

Atomic Physics · Physics 2024-10-03 T. Rook , D. Habibović , C. Figueira de Morisson Faria

In Part I of this two-part series, the reverse perturbation method for shearing simple liquids [Phys. Rev. E 59, 4894 (1999)] was extended to systems of interacting particles with time-discrete stochastic dynamics. For verification, in this…

Soft Condensed Matter · Physics 2019-10-16 Arash Nikoubashman , Thomas Ihle