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We introduce non-equilibrium molecular hydrogen chemistry into the radiation hydrodynamics code Ramses-RT. This is an adaptive mesh refinement grid code with radiation hydrodynamics that couples the thermal chemistry of hydrogen and helium…

Astrophysics of Galaxies · Physics 2018-09-07 Sarah Nickerson , Romain Teyssier , Joakim Rosdahl

We present a comprehensive analytical study of radiative transfer using the method of moments and include the effects of non-isotropic scattering in the coherent limit. Within this unified formalism, we derive the governing equations and…

Earth and Planetary Astrophysics · Physics 2015-06-19 Kevin Heng , João M. Mendonça , Jae-Min Lee

Advection-Diffusion-Reaction (ADR) Partial Differential Equations (PDEs) appear in a wide spectrum of applications such as chemical reactors, concentration flows, and biological systems. A large number of these applications require the…

Systems and Control · Electrical Eng. & Systems 2022-03-29 Ahmed Elkhashap , Dirk Abel

An implicit scheme for steady state solutions of diatomic gas flow is presented. The method solves the Rykov model equation in the finite volume discrete velocity method (DVM) framework, in which the translational and rotational degrees of…

Computational Physics · Physics 2018-11-01 Ruifeng Yuan , Chengwen Zhong

Underwater acoustic target recognition is critical for maritime applications, yet it faces challenges arising from the complex and diverse nature of ship-radiated noise. To address these issues, we propose a robust deep learning-based…

Signal Processing · Electrical Eng. & Systems 2026-05-22 Jiaping Yu , Shefeng Yan , Linlin Mao , Zeping Sui , Chunjin Jiang

In this work, we review the framework of the Virtual Element Method (VEM) for a model in magneto-hydrodynamics (MHD), that incorporates a coupling between electromagnetics and fluid flow, and allows us to construct novel discretizations for…

Numerical Analysis · Mathematics 2021-04-12 Sebastian Naranjo-Alvarez , Vrushali Bokil , Vitaliy Gyrya , Gianmarco Manzini

In this paper, a high-order gas-kinetic scheme is developed for the equation of radiation hydrodynamics in equilibrium-diffusion limit which describes the interaction between matter and radiation. To recover RHE, the Bhatnagar-Gross-Krook…

Numerical Analysis · Mathematics 2021-10-14 Yaqing Yang , Liang Pan , Wenjun Sun

This paper presents an arbitrary h.o. accurate ADER DG method on space-time adaptive meshes (AMR) for the solution of two important families of non-linear time dependent PDE for compr. dissipative flows: the compr. Navier-Stokes equations…

Numerical Analysis · Mathematics 2021-07-22 Francesco Fambri , Michael Dumbser , Olindo Zanotti

We study modifications of the Viterbi Training (VT) algorithm to estimate emission parameters in Hidden Markov Models (HMM) in general, and in mixure models in particular. Motivated by applications of VT to HMM that are used in speech…

Statistics Theory · Mathematics 2007-06-13 J. Lember , A. Koloydenko

We address the challenge of parameter-efficient fine-tuning (PEFT) for three-dimensional (3D) U-Net-based denoising diffusion probabilistic models (DDPMs) in magnetic resonance imaging (MRI) image generation. Despite its practical…

Image and Video Processing · Electrical Eng. & Systems 2025-07-25 Binghua Li , Ziqing Chang , Tong Liang , Chao Li , Toshihisa Tanaka , Shigeki Aoki , Qibin Zhao , Zhe Sun

The problem of the resolution of turbulent flows in adaptive mesh refinement (AMR) simulations is investigated by means of 3D hydrodynamical simulations in an idealised setup, representing a moving subcluster during a merger event. AMR…

Astrophysics · Physics 2009-11-13 L. Iapichino , J. Adamek , W. Schmidt , J. C. Niemeyer

The time dependent non-equilibrium radiation diffusion equations are important for solving the transport of energy through radiation in optically thick regimes and find applications in several fields including astrophysics and inertial…

Numerical Analysis · Mathematics 2014-03-05 Bobby Philip , Zhen Wang , Mark Berrill , Manuel Rodriguez Rodriguez , Michael Pernice

ADER (Arbitrary DERivative in space and time) methods for the time-evolution of hyperbolic conservation laws have recently generated a fair bit of interest. The ADER time update can be carried out in a single step, which is desirable in…

Computational Physics · Physics 2010-06-23 Dinshaw S. Balsara , Chad Meyer , Michael Dumbser , Huijing Du , Zhiliang Xu

We assess the validity of a single step Godunov scheme for the solution of the magneto-hydrodynamics equations in more than one dimension. The scheme is second-order accurate and the temporal discretization is based on the dimensionally…

Instrumentation and Methods for Astrophysics · Physics 2014-11-20 A. Mignone , P. Tzeferacos

In recent years the technique of Adaptive Mesh Refinement (AMR) has been successfully applied to several astrophysical problems. This method should also allow a consistent multi-dimensional modelling of supernova explosions. In this…

Astrophysics · Physics 2009-09-25 K. Kifonidis , T. Plewa , E. Mueller

The reduction of the computational effort is desirable for the simulation of marine ecosystem models. Using a marine ecosystem model, the assessment and the validation of annual periodic solutions (i.e., steady annual cycles) against…

Populations and Evolution · Quantitative Biology 2022-07-29 Markus Pfeil , Thomas Slawig

We test a new "hybrid" scheme for simulating dynamical fluid flows in which cylindrical components of the momentum are advected across a rotating Cartesian coordinate mesh. This hybrid scheme allows us to conserve angular momentum to…

Solar and Stellar Astrophysics · Physics 2015-06-19 Zachary D. Byerly , Bryce Adelstein-Lelbach , Joel E. Tohline , Dominic C. Marcello

Analyzing 3D anisotropic materials presents significant challenges, especially when assessing 3D orientations, material distributions, and anisotropies through scattered light, due to the inherently vectorial nature of light-matter…

Optics · Physics 2024-04-29 ChulMin Oh , Herve Hugonnet , Juheon Lee , YongKeun Park

Two-stream radiative transfer is a workhorse in the Earth, planetary and exoplanetary sciences due to its simplicity and ease of implementation. However, a longstanding limitation of the two-stream approximation is its inaccuracy in the…

Earth and Planetary Astrophysics · Physics 2018-08-08 Kevin Heng , Matej Malik , Daniel Kitzmann

Radiation is crucial not only for observing astrophysical objects, but also for transporting energy and momentum. However, accurate on-the-fly radiation transport in astrophysical simulations is challenging and computationally expensive.…

Instrumentation and Methods for Astrophysics · Physics 2025-03-24 Jing-Ze Ma , Rüdiger Pakmor , Stephen Justham , Selma E. de Mink