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We study the formation of the Stokes profiles of the He I multiplet at 10830 A when relaxing two of the approximations that are often considered in the modeling of this multiplet, namely the lack of self-consistent radiation transfer and…

Solar and Stellar Astrophysics · Physics 2023-07-05 Andres Vicente Arevalo , Jiri Stepan , Tanausu del Pino Aleman , Maria Jesus Martinez Gonzalez

In this paper, a fast synthetic iterative scheme is developed to accelerate convergence for the implicit DOM based on the stationary phonon BTE. The key innovative point of the present scheme is the introduction of the macroscopic synthetic…

Computational Physics · Physics 2018-12-18 Chuang Zhang , Songze Chen , Zhaoli Guo , Lei Wu

Astronomical imaging using aperture synthesis telescopes requires deconvolution of the point spread function as well as calibration of instrumental and atmospheric effects. In general, such effects are time-variable and vary across the…

Astrophysics · Physics 2009-11-13 S. Bhatnagar , T. J. Cornwell , K. Golap , Juan M. Uson

Interpreting the data from radio detectors for extensive air showers typically relies on Monte-Carlo based simulation codes, which, despite their accuracy are computationally expensive and present bottlenecks for analyses. To address this…

High Energy Astrophysical Phenomena · Physics 2025-05-16 Mitja Desmet , Keito Watanabe , Tim Huege , Stijn Buitink

Radiative transfer modeling of spectral lines including partial redistribution (PRD) effects requires the evaluation of the ratio of the emission to the absorption profile. This quantity requires a large amount of computational work if one…

Solar and Stellar Astrophysics · Physics 2015-06-05 Jorrit Leenaarts , Tiago Pereira , Han Uitenbroek

The hyperbolic Radon transform is a commonly used tool in seismic processing, for instance in seismic velocity analysis, data interpolation and for multiple removal. A direct implementation by summation of traces with different moveouts is…

Numerical Analysis · Mathematics 2017-05-24 Viktor V. Nikitin , Fredrik Andersson , Marcus Carlsson , Anton A. Duchkov

For the Stokes equation over 2D and 3D domains, explicit a posteriori and a priori error estimation are novelly developed for the finite element solution. The difficulty in handling the divergence-free condition of the Stokes equation is…

Numerical Analysis · Mathematics 2020-06-05 Xuefeng Liu , Mitsuhiro Nakao , Chun'guang You , Shin'ichi Oishi

Distributed Acoustic Sensing (DAS) is a novel technology that allows sampling of the seismic wavefield densely over a broad frequency band. This makes it an ideal tool for surface wave studies. In this study, we evaluate the potential of…

The emergence of three-dimensional magneto-hydrodynamic (MHD) simulations of stellar atmospheres has sparked a need for efficient radiative transfer codes to calculate detailed synthetic spectra. We present RH 1.5D, a massively parallel…

Solar and Stellar Astrophysics · Physics 2015-01-21 Tiago M. D. Pereira , Han Uitenbroek

We derive a Ewald decomposition for the Stokeslet in planar periodicity and a novel PME-type O(N log N) method for the fast evaluation of the resulting sums. The decomposition is the natural 2P counterpart to the classical 3P decomposition…

Fluid Dynamics · Physics 2011-11-09 Dag Lindbo , Anna-Karin Tornberg

We develop a novel algorithm for sparse Stokes parameters imaging in radio interferometry under the polarization constraint. The latter is a physical non-linear relation between the Stokes parameters, imposing that the polarization…

Instrumentation and Methods for Astrophysics · Physics 2018-07-18 Jasleen Birdi , Audrey Repetti , Yves Wiaux

Profile comparison of the Stokes parameters $V$ and $I$ is a powerful tool for maser data analysis, providing the first direct methods for unambiguous determination of (1) the maser saturation stage, (2) the amplification optical depth and…

Astrophysics · Physics 2009-10-30 Moshe Elitzur

A large set of high precision full-Stokes spectropolarimetric observations of the He-D3 line in spicules has been recorded with the ZIMPOL polarimeter at the Gregory-Coude Telescope in Locarno. The observational technique allow us to obtain…

Solar and Stellar Astrophysics · Physics 2010-11-26 R. Ramelli , M. Bianda , L. Merenda , J. Trujillo Bueno

This paper describes the data preprocessing and reduction methods together with SLODAR analysis and wind profiling techniques for GeMS: the Gemini MCAO System. The wavefront gradient measurements of the five GeMS's Shack-Hartmann sensors,…

Instrumentation and Methods for Astrophysics · Physics 2015-06-11 Angela Cortés , Benoit Neichel , Andrés Guesalaga , James Osborn , Francois Rigaut , Dani Guzman

The present paper proposes an inf-sup stable divergence free virtual element method and associated a priori, and a posteriori error analysis to approximate the eigenvalues and eigenfunctions of the Stokes spectral problem in one shot. For…

Numerical Analysis · Mathematics 2022-12-06 Dibyendu Adak , Felipe Lepe , Gonzalo Rivera

We derive a generalization of forward fitting for X-ray spectroscopy to include linear polarization of X-ray sources, appropriate for the anticipated next generation of space-based photoelectric polarimeters. We show that the inclusion of…

Instrumentation and Methods for Astrophysics · Physics 2017-04-05 Tod E. Strohmayer

Large-scale dynamic inverse problems are often ill-posed due to model complexity and the high dimensionality of the unknown parameters. Regularization is commonly employed to mitigate ill-posedness by incorporating prior information and…

Numerical Analysis · Mathematics 2026-01-21 Aryeh Keating , Mirjeta Pasha

The Mg II k resonance line is commonly used for diagnosing the solar chromosphere. We theoretically investigated its intensity and polarization in solar prominences, taking 3D radiative transfer and Hanle and Zeeman effects into account. We…

Solar and Stellar Astrophysics · Physics 2024-09-25 Jiří Štěpán , Tanausú del Pino Alemán , Javier Trujillo Bueno

The large domain discrepancy between faces captured in polarimetric (or conventional) thermal and visible domain makes cross-domain face verification a highly challenging problem for human examiners as well as computer vision algorithms.…

Computer Vision and Pattern Recognition · Computer Science 2018-12-14 He Zhang , Benjamin S. Riggan , Shuowen Hu , Nathaniel J. Short , Vishal M. Patel

This paper describes the recently developed mixed mimetic spectral element method for the Stokes problem in the vorticity-velocity-pressure formulation. This compatible discretization method relies on the construction of a conforming…

Numerical Analysis · Computer Science 2012-06-14 Jasper Kreeft , Marc Gerritsma
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