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The combination of photometry, spectroscopy and spectropolarimetry of the chemically peculiar stars often aims to study the complex physical phenomena such as stellar pulsation, chemical inhomogeneity, magnetic field and their interplay…

Solar and Stellar Astrophysics · Physics 2017-01-25 Santosh Joshi , Eugene Semenko , A. Moiseeva , Kaushal Sharma , Y. C. Joshi , M. Sachkov , Harinder P. Singh , Yerra Bharat Kumar

In this paper, we consider clustering based on principal component analysis (PCA) for high-dimension, low-sample-size (HDLSS) data. We give theoretical reasons why PCA is effective for clustering HDLSS data. First, we derive a geometric…

Statistics Theory · Mathematics 2015-03-17 Kazuyoshi Yata , Makoto Aoshima

Context. Solar filament oscillations have been observed for many years, but recent advances in telescope capabilities now enable daily monitoring of these periodic motions, offering valuable insights into the structure of filaments. A…

Solar and Stellar Astrophysics · Physics 2025-02-19 G. Castelló , M. Luna , J. Terradas

High fidelity models used in many science and engineering applications couple multiple physical states and parameters. Inverse problems arise when a model parameter cannot be determined directly, but rather is estimated using (typically…

Optimization and Control · Mathematics 2020-12-30 Isaac Sunseri , Joseph Hart , Bart van Bloemen Waanders , Alen Alexanderian

The statistical description of Giant Molecular Cloud (GMC) properties relies heavily on the performance of automatic identification algorithms, which are often seriously affected by the survey design. The algorithm we designed, SCIMES…

Astrophysics of Galaxies · Physics 2017-01-11 Dario Colombo , Erik Rosolowsky , Adam Ginsburg , Ana Duarte-Cabral , Annie Hughes

Principal component analysis (PCA) is an important tool in exploring data. The conventional approach to PCA leads to a solution which favours the structures with large variances. This is sensitive to outliers and could obfuscate interesting…

Methodology · Statistics 2015-06-16 A. A. Akinduko , A. N. Gorban

Observations of the solar surface reveal the presence of flows with length scales of around $35$ Mm, commonly referred to as supergranules. Inferring the sub-surface flow profile of supergranules from measurements of the surface and…

Solar and Stellar Astrophysics · Physics 2016-08-03 Jishnu Bhattacharya , Shravan M. Hanasoge

Recent high-resolution observations have shown stellar winds to harbour complexities which strongly deviate from spherical symmetry, generally assumed as standard wind model. One such morphology is the archimedean spiral, generally believed…

Solar and Stellar Astrophysics · Physics 2015-07-15 Ward Homan , Leen Decin , Alex de Koter , Allard Jan van Marle , Robin Lombaert , Wouter Vlemmings

The complex spectropolarimetric patterns around strong chromospheric lines, the result of subtle spectroscopic and transport mechanisms, are sensitive, sometimes in unexpected ways, to the presence of magnetic fields in the chromosphere,…

Solar and Stellar Astrophysics · Physics 2017-10-12 R. Manso Sainz , T. del Pino Alemán , R. Casini

Reconstructing models from unorganized point clouds presents a significant challenge, especially when the models consist of multiple components represented by their surface point clouds. Such models often involve point clouds with noise…

Computational Geometry · Computer Science 2025-08-26 Yu Chen , Hongwei Lin

This is the third paper of a series aimed at studying the chromosphere of active binary systems using the information provided for several optical spectroscopic features. High resolution echelle spectra including all the optical…

In the present work, we study the periodicities of oscillations in dark fine structures using observations of a network and a semi-active region close to the solar disk center. We simultaneously obtained spatially high resolution time…

Solar and Stellar Astrophysics · Physics 2015-06-22 Z. F. Bostanci , A. Gultekin , N. Al

Sky/cloud images captured by ground-based cameras (a.k.a. whole sky imagers) are increasingly used nowadays because of their applications in a number of fields, including climate modeling, weather prediction, renewable energy generation,…

Computer Vision and Pattern Recognition · Computer Science 2016-06-14 Soumyabrata Dev , Yee Hui Lee , Stefan Winkler

Quantitative thermodynamical, dynamical and magnetic properties of the solar and stellar plasmas are obtained by interpreting their emergent non-polarized and polarized spectrum. This inference requires the selection of a set of spectral…

Solar and Stellar Astrophysics · Physics 2016-05-25 A. Asensio Ramos , J. de la Cruz Rodriguez , M. J. Martinez Gonzalez , A. Pastor Yabar

Neural networks-based learning of the distribution of non-dispatchable renewable electricity generation from sources such as photovoltaics (PV) and wind as well as load demands has recently gained attention. Normalizing flow density models…

Machine Learning · Computer Science 2022-01-10 Eike Cramer , Alexander Mitsos , Raul Tempone , Manuel Dahmen

Sky/cloud imaging using ground-based Whole Sky Imagers (WSI) is a cost-effective means to understanding cloud cover and weather patterns. The accurate segmentation of clouds in these images is a challenging task, as clouds do not possess…

Computer Vision and Pattern Recognition · Computer Science 2017-01-18 Soumyabrata Dev , Yee Hui Lee , Stefan Winkler

Solar observations at sub-mm, mm and cm wavelengths offer a straightforward diagnostic of physical conditions in the solar atmosphere because they yield measurement of brightness temperature which, for optically thick features, equals…

Solar and Stellar Astrophysics · Physics 2022-09-07 Costas Alissandrakis , Timothy Bastian , Roman Brajša

Cloud Optical Thickness (COT) is a critical cloud property influencing Earth's climate, weather, and radiation budget. Satellite radiance measurements enable global COT retrieval, but challenges like 3D cloud effects, viewing angles, and…

Computer Vision and Pattern Recognition · Computer Science 2025-06-02 Zahid Hassan Tushar , Adeleke Ademakinwa , Jianwu Wang , Zhibo Zhang , Sanjay Purushotham

With the increasing number of directly imaged giant exoplanets the current atmosphere models are often not capable of fully explaining the spectra and luminosity of the sources. A particularly challenging component of the atmosphere models…

Earth and Planetary Astrophysics · Physics 2015-06-11 Veselin B. Kostov , Dániel Apai

The influence of the convective structure of the solar photosphere on the shifts of spectral lines of iron was studied. Line profiles in the visible and infrared spectrum were synthesized with the use of 2-D time-dependent hydrodynamic…

Solar and Stellar Astrophysics · Physics 2010-04-21 V. A. Sheminova , A. S. Gadun
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