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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

In this paper, we propose high order numerical methods to solve a 2D advection diffusion equation, in the highly oscillatory regime. We use an integrator strategy that allows the construction of arbitrary high-order schemes {leading} to an…

Numerical Analysis · Mathematics 2024-11-11 Clarissa Astuto

In this work, we propose an adaptive spectral element algorithm for solving nonlinear optimal control problems. The method employs orthogonal collocation at the shifted Gegenbauer-Gauss points combined with very accurate and stable…

Optimization and Control · Mathematics 2023-03-06 Kareem T. Elgindy

Exact models of uniformly rotating strange stars, built of self bound quark matter, are calculated within the framework of general relativity. This is made possible thanks to a new numerical technique capable to handle the strong density…

Astrophysics · Physics 2010-11-19 E. Gourgoulhon , P. Haensel , R. Livine , E. Paluch , S. Bonazzola , J. A. Marck

A new projection method based on radial basis functions (RBFs) is presented for discretizing the incompressible unsteady Stokes equations in irregular geometries. The novelty of the method comes from the application of a new technique for…

Numerical Analysis · Mathematics 2015-09-21 Edward J. Fuselier , Varun Shankar , Grady B. Wright

We present a ray-tracing technique for radiative transfer modeling of complex three-dimensional (3D) structures which include dense regions of high optical depth like in dense molecular clouds, circumstellar disks, envelopes of evolved…

Astrophysics · Physics 2009-11-11 J. Steinacker , A. Bacmann , Th. Henning

Space-based photometry has substantially increased the number of pulsating stars found in binary systems by more than four orders of magnitude. Combined with high-resolution spectroscopy, high-precision photometry offers model-independent…

Instrumentation and Methods for Astrophysics · Physics 2025-12-18 Ema Šipková , Alex Kemp , Dario Fritzewski , Andrew Tkachenko , Dominic M. Bowman , Conny Aerts , Jasmine Vrancken

The numerical modeling of binary neutron star mergers has become a subject of much interest in recent years. While a full and accurate model of this phenomenon would require the evolution of the equations of relativistic hydrodynamics along…

Astrophysics · Physics 2009-10-31 F. Douglas Swesty , Edward Y. M. Wang , Alan C. Calder

We present a unified framework to derive fundamental stellar parameters by combining all available observational and theoretical information for a star. The algorithm relies on the method of Bayesian inference, which for the first time…

Solar and Stellar Astrophysics · Physics 2015-06-18 Ralph Schönrich , Maria Bergemann

An optimal maximum-likelihood technique for computing point-source image centroids from many, slightly offset, CCD frames is presented. The method is especially useful for measuring stellar proper motions from data taken with the Wide Field…

Astrophysics · Physics 2015-06-24 Rodrigo Ibata , Geraint Lewis

We propose an iterative solution method for the 3D high-frequency Helmholtz equation that exploits a contour integral formulation of spectral projectors. In this framework, the solution in certain invariant subspaces is approximated by…

Numerical Analysis · Mathematics 2018-11-30 Xiao Liu , Yuanzhe Xi , Yousef Saad , Maarten V. de Hoop

Diagrammatic techniques to compute perturbatively the spectral properties of Euclidean Random Matrices in the high-density regime are introduced and discussed in detail. Such techniques are developed in two alternative and very different…

Disordered Systems and Neural Networks · Physics 2011-08-31 T. S. Grigera , V. Martin-Mayor , G. Parisi , P. Urbani , P. Verrocchio

Line-by-line calculations are becoming the standard procedure for carrying spectral simulations. However, it is important to insure the accuracy of such spectral simulations through the choice of adapted models for the simulation of key…

Optics · Physics 2007-05-23 M. Lino da Silva

Doppler tomography is a method to compute the emissivity distribution within the co-rotating frames of binary stars from observations of their emission line profiles at multiple orbital phases. A key assumption of the method as it is…

Solar and Stellar Astrophysics · Physics 2021-12-08 T. R. Marsh

We present a 3D Bayesian method to model the kinematics of strongly lensed galaxies from spatially-resolved emission-line observations. This technique enables us to simultaneously recover the lens-mass distribution and the source kinematics…

Astrophysics of Galaxies · Physics 2018-09-21 Francesca Rizzo , Simona Vegetti , Filippo Fraternali , Enrico Di Teodoro

Stellar models are calculated in the approximation of a uniform density distribution. Variational method was used for determination of the boundary of a stability loss, for stellar masses in the range from 2 up to $10^5$ $M_{\odot}$. The…

High Energy Astrophysical Phenomena · Physics 2025-11-06 G. S. Bisnovatyi-Kogan , E. A. Patraman

We present an equation of state for elastic matter which allows for purely longitudinal elastic waves in all propagation directions, not just principal directions. The speed of these waves is equal to the speed of light whereas the…

General Relativity and Quantum Cosmology · Physics 2009-11-10 Max Karlovini , Lars Samuelsson

In this paper, the gravitational field equations for static spherically symmetric perfect fluid models with a polytropic equation of state, $p=k\rho^{1+1/n}$, are recast into two complementary 3-dimensional {\it regular} systems of ordinary…

General Relativity and Quantum Cosmology · Physics 2009-10-31 U. S. Nilsson , C. Uggla

Recent advances in 3D Gaussian Splatting (3DGS) have enabled highly efficient and photorealistic novel view synthesis. However, segmenting objects accurately in 3DGS remains challenging due to the discrete nature of Gaussian…

Computer Vision and Pattern Recognition · Computer Science 2026-04-17 Yi He , Tao Wang , Yi Jin , Congyan Lang , Yidong Li , Haibin Ling

Young, intermediate-mass stars are experiencing renewed interest as targets for direct-imaging planet searches. However, these types of stars are part of multiple systems more often than not. Close stellar companions affect the formation…