English
Related papers

Related papers: Full non-LTE multi-level radiative transfer I. An …

200 papers

Instantaneous heat transfer between different phases is a common assumption for modeling heat transfer in porous media, known as Local Thermal Equilibrium (LTE). This assumption may not hold in certain technical and environmental…

We present a new Lattice Boltzmann (LB) formulation to solve the Maxwell equations for electromagnetic (EM) waves propagating in a heterogeneous medium. By using a pseudo-vector discrete Boltzmann distribution, the scheme is shown to…

Instrumentation and Methods for Astrophysics · Physics 2015-05-30 Shravan M. Hanasoge , Sauro Succi , Steven A. Orszag

We present integral equations for the scattering amplitudes of three scalar particles, using the Faddeev channel decomposition, which can be readily extended to any finite number of particles of any helicity. The solution of these…

High Energy Physics - Theory · Physics 2015-06-25 Marcus Alfred , Petero Kwizera , James V. Lindesay , H. Pierre Noyes

We consider the classical integral equation reformulation of the radiative transport equation (RTE) in a heterogeneous medium, assuming isotropic scattering. We prove an estimate for the norm of the integral operator in this formulation…

Numerical Analysis · Mathematics 2019-03-21 J. C. H. Blake , I. G. Graham , F. Scheben , A. Spence

We describe first-principles in-plane calculations of non-sequential triple ionization (NSTI) of atoms in a linearly polarized intense laser pulse. In a fully classically correlated description, all three electrons respond dynamically to…

Atomic Physics · Physics 2009-11-11 Phay J. Ho , J. H. Eberly

The interpretation of the intensity and polarization of the spectral line radiation produced in the atmosphere of the Sun and of other stars requires solving a radiative transfer problem that can be very complex, especially when the main…

Solar and Stellar Astrophysics · Physics 2015-06-16 Jiri Stepan , Javier Trujillo Bueno

Starting from a quantum description of multiple Lambda-type 3-level atoms driven with a coherent microwave field and incoherent optical pumping, we derive a microscopic model of lasing from which we move towards a consistent macroscopic…

Quantum Physics · Physics 2022-09-01 Nicholas Werren , Erik Gauger , Peter Kirton

Achieving efficient and accurate simulation of the radiative transfer has long been a research challenge. Here we introduce the general synthetic iterative scheme as an easy-to-implement approach to address this issue. First, a macroscopic…

Computational Physics · Physics 2025-07-08 Kaiyuan Wang , Yanbing Zhang , Qi Li , Lei Wu

The nonlinear Fourier transform (NFT) decomposes waveforms propagating through optical fiber into nonlinear degrees of freedom, which are preserved during transmission. By encoding information on the nonlinear spectrum, a transmission…

Signal Processing · Electrical Eng. & Systems 2020-12-24 Jan-Willem Goossens , Hartmut Hafermann , Yves Jaouën

An iterative method is derived for image reconstruction. Among other attributes, this method allows constraints unrelated to the radiation measurements to be incorporated into the reconstructed image. A comparison is made with the widely…

Computational Physics · Physics 2011-01-06 Clinton DeW. Van Siclen

We develop a numerical solver for the integral-differential equations, which describes the radiative transfer of photon distribution in the frequency space with resonant scattering of Lyalpha photons by hydrogen gas in the early universe.…

Cosmology and Nongalactic Astrophysics · Physics 2009-11-13 Ishani Roy , Jing-Mei Qiu , Chi-Wang Shu , Li-Zhi Fang

Motivated by observational and theoretical work which both suggest very small scale ($\lesssim 1\,$pc) structure in the circum-galactic medium of galaxies and in other environments, we study Lyman-$\alpha$ (Ly$\alpha$) radiative transfer in…

Astrophysics of Galaxies · Physics 2017-11-22 Max Gronke , Mark Dijkstra , Michael McCourt , S. Peng Oh

Aiming at testing the validity of our magnesium atomic model and investigating the effects of non-local thermodynamical equilibrium (NLTE) on the formation of the H-band neutral magnesium lines, we derive the differential Mg abundances from…

Solar and Stellar Astrophysics · Physics 2017-01-25 Junbo Zhang , Jianrong Shi , Kaike Pan , Carlos Allende Prieto , Chao Liu

We consider the numerical approximation of boundary conditions in radiative transfer problems by a perfectly matched layer approach. The main idea is to extend the computational domain by an absorbing layer and to use an appropriate…

Numerical Analysis · Mathematics 2018-02-26 Herbert Egger , Matthias Schlottbom

The possibility of significant systematic errors due to the use of 1D homogeneous atmospheres in lithium-abundance determinations of cool stars motivates a study of non-local-thermodynamic-equilibrium (NLTE) effects on Li I line formation…

Astrophysics · Physics 2009-10-30 Dan Kiselman

A method is proposed to solve the challenging problem of determining the supratransmission threshold (onset of instability of harmonic boundary driving inside a band gap) in multicomponent nonintegrable nonlinear systems. It is successfully…

Pattern Formation and Solitons · Physics 2010-08-12 P. Anghel-Vasilescu , J. Dorignac , F. Geniet , J. Leon , M. Taki

An algorithm is proposed to implement unsteady jump boundary conditions, presenting discontinuity in physical quantities, within the lattice Boltzmann method (LBM). This is useful to tackle problems involving mass or heat transfer through…

Computational Physics · Physics 2018-11-06 Badr Kaoui

Implementing computational boundary conditions, such as perfectly matched layers PML does have advantages for forwarding modeling of the earth's crust. The mathematical modeling of many physical problems encountered in industrial…

Geophysics · Physics 2019-11-12 P. Contreras , G. Larrazabal , C. Florio

In this paper, we study the impact of computational complexity on the throughput limits of the {\color{black}fast Fourier transform (FFT)} algorithm for {\color{black}orthogonal frequency division multiplexing(OFDM)} waveforms. Based on the…

Signal Processing · Electrical Eng. & Systems 2022-09-30 Saulo Queiroz , João P. Vilela , Edmundo Monteiro

Rabi frequencies for multiphoton absorption by atoms or molecules that can be characterized as two- or three-level systems are obtained in the cases of single and double laser perturbations. If the ambiguity in the origin of absolute energy…

Quantum Physics · Physics 2007-05-23 Pedro F. Gonzalez-Diaz