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On an example of the open nonlinear electrodynamic system - transverse non-homogeneous, isotropic, nonlinear (a Kerr-like dielectric nonlinearity) dielectric layer, the algorithms of solution of the diffraction problem of a plane wave on…

Computational Physics · Physics 2007-05-23 V. V. Yatsyk

Cosmic rays (CRs) are an important source of feedback in a variety of astrophysical contexts. Magneto-hydrodynamical (MHD) simulations treating CRs as a fluid have shown that how their feedback operates is strongly dependent on their…

Astrophysics of Galaxies · Physics 2025-09-25 Joki Rosdahl , Yohan Dubois , Benoit Commercon , Nimatou Diallo , Nai Chieh Lin , Alexandre Marcowith

Radiative transfer simulations are now at the forefront of numerical astrophysics. They are becoming crucial for an increasing number of astrophysical and cosmological problems; at the same time their computational cost has come to the…

In this paper, an efficient iterative method is proposed for solving multiple scattering problem in locally inhomogeneous media. The key idea is to enclose the inhomogeneity of the media by well separated artificial boundaries and then…

Numerical Analysis · Mathematics 2019-10-23 Ziqing Xie , Rui Zhang , Bo Wang , Li-lian Wang

Cosmic rays (CRs) are dynamically important for the formation and evolution of galaxies by regulating star formation and by powering galactic outflows. However, to what extent CRs regulate galaxy formation depends on the coupling strength…

Astrophysics of Galaxies · Physics 2023-12-27 Philipp Girichidis , Maria Werhahn , Christoph Pfrommer , Rüdiger Pakmor , Volker Springel

Low-energy cosmic rays (CRs) are confined by self-generated MHD waves in the mostly neutral ISM. We show that the CR transport equation can be expressed as a continuity equation for the CR number density involving an effective convection…

Astrophysics · Physics 2009-11-10 Paolo Padoan , John Scalo

We study the inertial modes of slowly rotating, fully relativistic compact stars. The equations that govern perturbations of both barotropic and non-barotropic models are discussed, but we present numerical results only for the barotropic…

General Relativity and Quantum Cosmology · Physics 2009-11-07 K. H. Lockitch , J. L. Friedman , N. Andersson

A fourth-order compact scheme is proposed for a fourth-order subdiffusion equation with the first Dirichlet boundary conditions. The fourth-order problem is firstly reduced into a couple of spatially second-order system and we use an…

Numerical Analysis · Mathematics 2019-07-04 Jialing Zhong , Hong-lin Liao , Bingquan Ji , Luming Zhang

In this paper, we shall consider spherically symmetric spacetime solutions describing the interior of stellar compact objects, in the context of higher-order curvature theory of the f(R) type. We shall derive the non--vacuum field equations…

General Relativity and Quantum Cosmology · Physics 2021-06-28 G. G. L. Nashed , S. D. Odintsov , V. K. Oikonomou

Galactic cosmic rays are a ubiquitous source of ionisation of the interstellar gas, competing with UV and X-ray photons as well as natural radioactivity in determining the fractional abundance of electrons, ions and charged dust grains in…

High Energy Astrophysical Phenomena · Physics 2018-06-27 Marco Padovani , Alexei V. Ivlev , Daniele Galli , Paola Caselli

In the last decade, a number of experiments dealt with the problem of measuring the arrival direction distribution of cosmic rays, looking for information on the propagation mechanisms and the identification of their sources. Any deviation…

Instrumentation and Methods for Astrophysics · Physics 2015-06-12 Roberto Iuppa , Giuseppe Di Sciascio

Based on the Kraus-form solution to the master equation describing diffusion we develop an integral form solution by using the method of integration within ordered product of operators, i.e., the evolution law of density operator in…

Quantum Physics · Physics 2015-11-18 F. Gao , H. Y. Fan , F. Shuang , X. B. Tang

Space and time scales are not independent in diffusion. In fact, numerical simulations show that different patterns are obtained when space and time steps ($\Delta x$ and $\Delta t$) are varied independently. On the other hand, anisotropy…

patt-sol · Physics 2015-06-26 Rui Dilao , Joaquim Sainhas

We consider the numerical approximation of the radiative transfer equation using discontinuous angular and continuous spatial approximations for the even parts of the solution. The even-parity equations are solved using a diffusion…

Numerical Analysis · Mathematics 2019-09-19 Olena Palii , Matthias Schlottbom

Radiative transfer (RT) problems in which the source function includes a scattering-like integral are typical two-points boundary problems. Their solution via differential equations implies to make hypotheses on the solution itself, namely…

Solar and Stellar Astrophysics · Physics 2015-05-30 E. Simonneau , O. Cardona , L. Crivellari

A method is developed for solving quasilinear convection diffusion problems starting on a coarse mesh where the data and solution-dependent coefficients are unresolved, the problem is unstable and approximation properties do not hold. The…

Numerical Analysis · Mathematics 2015-02-10 Sara Pollock

One of the main challenges in diffusion-based molecular communication is dealing with the non-linearity of reaction-diffusion chemical equations. While numerical methods can be used to solve these equations, a change in the input signals or…

Information Theory · Computer Science 2021-06-04 Hamidreza Abin , Amin Gohari , Masoumeh Nasiri-Kenari

We investigate iterated Tikhonov methods coupled with a Kaczmarz strategy for obtaining stable solutions of nonlinear systems of ill-posed operator equations. We show that the proposed method is a convergent regularization method. In the…

Numerical Analysis · Mathematics 2020-12-23 J. Baumeister , A. De Cezaro , A. Leitao

This work presents a space-time isogeometric analysis of biharmonic wave problem, in contrast to the more common application of space-time methods to second order wave equations. We first establish the unique solvability of the continuous…

Numerical Analysis · Mathematics 2026-04-06 S. Chauhan , S. Chaudhary

A laser diffraction experiment was conducted to study light propagation in air. The experiment is easy to reproduce and it is based on simple optical principles. Two optical sensors (segmented photo-diodes) are used for measuring the…

Astrophysics · Physics 2007-05-23 C. E. Navia , C. R. A. Augusto , D. F. Franceschini , M. B. Robba , K. H. Tsui