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Multi-level non-local thermodynamic equilibrium (NLTE) radiation transfer calculations have become standard throughout the stellar atmospheres community and are applied to all types of stars as well as dynamical systems such as novae and…

Solar and Stellar Astrophysics · Physics 2014-07-02 Peter H. Hauschildt , E. Baron

We present the results of a series of calculations studying the collapse of molecular cloud cores performed using a three-dimensional smoothed particle hydr odynamics code with radiative transfer in the flux-limited diffusion approximation.…

Astrophysics · Physics 2009-11-13 Stuart C. Whitehouse , Matthew R. Bate

This paper presents nonlinear iterative methods for the fundamental thermal radiative transfer (TRT) model defined by the time-dependent multifrequency radiative transfer (RT) equation and the material energy balance (MEB) equation. The…

Numerical Analysis · Mathematics 2024-09-24 Dmitriy Y. Anistratov

In this work we use models of molecular clouds (MC), and non-LTE radiative transfer calculations, to obtain a theoretical calibration of the relation between LTE 13CO column density and true column density in MCs. The cloud models consist…

Astrophysics · Physics 2008-02-03 Paolo Padoan , Mika Juvela , John Bally , AAke Nordlund

We introduce CRASH-AMR, a new version of the cosmological Radiative Transfer (RT) code CRASH, enabled to use refined grids. This new feature allows us to attain higher resolution in our RT simulations and thus to describe more accurately…

Cosmology and Nongalactic Astrophysics · Physics 2017-02-01 N. Hariharan , L. Graziani , B. Ciardi , F. Miniati , H. -J. Bungartz

Computationally expensive Radiative Transfer Models (RTMs) are widely used} to realistically reproduce the light interaction with the Earth surface and atmosphere. Because these models take long processing time, the common practice is to…

Diffusion models achieved great success in image synthesis, but still face challenges in high-resolution generation. Through the lens of discrete cosine transformation, we find the main reason is that \emph{the same noise level on a higher…

Computer Vision and Pattern Recognition · Computer Science 2023-09-08 Jiayan Teng , Wendi Zheng , Ming Ding , Wenyi Hong , Jianqiao Wangni , Zhuoyi Yang , Jie Tang

We present a new adaptive resolution technique for efficient particle-based multiscale molecular dynamics (MD) simulations. The presented approach is tailor-made for molecular systems where atomistic resolution is required only in spatially…

Soft Condensed Matter · Physics 2007-05-23 Matej Praprotnik , Luigi Delle Site , Kurt Kremer

Absorption line spectroscopy offers one of the best opportunities to constrain the properties of galactic outflows and the environment of the circumgalactic medium. Extracting physical information from line profiles is difficult, however,…

Astrophysics of Galaxies · Physics 2023-07-26 Cody Carr , Leo Michel-Dansac , Jeremy Blaizot , Claudia Scarlata , Alaina Henry , Anne Verhamme

We present a geometric multigrid solver for the M1 model of radiative transfer without source terms. In radiative hydrodynamics applications, the radiative transfer needs to be solved implicitly because of the fast propagation speed of…

Numerical Analysis · Mathematics 2022-09-28 Hélène Bloch , Pascal Tremblin , Matthias González , Edouard Audit

An accurate estimate of the inner edge of the habitable zone is critical for determining which exoplanets are potentially habitable and for designing future telescopes to observe them. Here, we explore differences in estimating the inner…

Accurate angular quadratures are crucial for the numerical solution of three-dimensional (3D) radiative transfer problems, especially when the spectral line polarisation produced by the scattering of anisotropic radiation is included. There…

Solar and Stellar Astrophysics · Physics 2021-01-27 Jaume Jaume Bestard , Jiří Štěpán , Javier Trujillo Bueno

This work presents efficient solution techniques for radiative transfer in the smoothed particle hydrodynamics discretization. Two choices that impact efficiency are how the material and radiation energy are coupled, which determines the…

Computational Physics · Physics 2021-03-17 Brody R. Bassett , J. Michael Owen , Thomas A. Brunner

We describe a general radiative equilibrium and temperature correction procedure for use in Monte Carlo radiation transfer codes with sources of temperature-independent opacity, such as astrophysical dust. The technique utilizes the fact…

Astrophysics · Physics 2010-04-08 J. E. Bjorkman , Kenneth Wood

We have developed a new model that uses a cellular approach to calculate radiative transfer of starlight through dusty media. The model is designed to be user friendly enough to be distributed as a tool for use by the general astronomical…

Astrophysics · Physics 2009-09-25 Matthew Trewhella , Barry F. Madore , Leslie Kuchinski

Physically realistic models of stellar spectra are needed in a variety of astronomical studies, from the analysis of fundamental stellar parameters, to studies of exoplanets and stellar populations in galaxies. Here we present a new version…

Solar and Stellar Astrophysics · Physics 2023-01-11 Jeffrey M. Gerber , Ekaterina Magg , Bertrand Plez , Maria Bergemann , Ulrike Heiter , Terese Olander , Richard Hoppe

We study improved degree distribution for Luby Transform (LT) codes which exhibits improved bit error rate performance particularly in low overhead regions. We construct the degree distribution by modifying Robust Soliton distribution. The…

Information Theory · Computer Science 2013-09-13 Zesong Fei , Congzhe Cao , Ming Xiao , Iqbal Hussain , Jingming Kuang

Realistic numerical simulations, i.e., those that make minimal use of ad hoc modeling, are essential for understanding the complex turbulent dynamics of the interiors and atmospheres of the Sun and other stars and the basic mechanisms of…

Solar and Stellar Astrophysics · Physics 2015-07-30 Alan A. Wray , Khalil Bensassi , Irina N. Kitiashvili , Nagi N. Mansour , Alexander G. Kosovichev

Thermal radiative transfer (TRT) is an essential piece of physics in inertial confinement fusion, high-energy density physics, astrophysics etc. The physical models of this type of problem are defined by strongly coupled differential…

Numerical Analysis · Mathematics 2025-08-06 Dmitriy Y. Anistratov , Terry S. Haut

This paper explores a machine learning approach for generating high resolution point clouds from a single-chip mmWave radar. Unlike lidar and vision-based systems, mmWave radar can operate in harsh environments and see through occlusions…