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Image data captured outdoors often exhibit unbounded scenes and unconstrained, varying lighting conditions, making it challenging to decompose them into geometry, reflectance, and illumination. Recent works have focused on achieving this…

Computer Vision and Pattern Recognition · Computer Science 2025-09-16 Lianjun Liao , Chunhui Zhang , Tong Wu , Henglei Lv , Bailin Deng , Lin Gao

Recent spectral graph sparsification techniques have shown promising performance in accelerating many numerical and graph algorithms, such as iterative methods for solving large sparse matrices, spectral partitioning of undirected graphs,…

Data Structures and Algorithms · Computer Science 2020-08-19 Ying Zhang , Zhiqiang Zhao , Zhuo Feng

Below 1 mHz, the power spectrum of helioseismic velocity measurements is dominated by the spectrum of convective motions (granulation and supergranulation) making it difficult to detect the low-order acoustic modes and the gravity modes. We…

Astrophysics · Physics 2008-10-31 S. Lefebvre , R. A. Garcia , S. J. Jimenez-Reyes , S. Turck-Chieze , S. Mathur

Reflection nebulae--dense cores--illuminated by surrounding stars offer a unique opportunity to directly test our quantitative model of grain alignment based on radiative torques (RATs) and to explore new effects arising from additional…

Astrophysics of Galaxies · Physics 2015-06-23 Thiem Hoang , A Lazarian , B-G Andersson

We present a detailed comparison between simulations and seeing-free observations that takes into account the crucial influence of instrumental image degradation. We use images of quiet Sun granulation taken in the blue, green and red…

Solar and Stellar Astrophysics · Physics 2015-05-13 Sven Wedemeyer-Böhm , Luc Rouppe van der Voort

Solar granulation consists of dynamic convective plasma cells that rise from the solar interior to the surface. The interaction between these plasma cells and the Sun's magnetic field provides valuable insights into plasma dynamics near the…

Solar and Stellar Astrophysics · Physics 2026-04-01 J. I. Campos Rozo , J. Jurčák , S. M. Díaz Castillo , M. van Noort

The mechanism and characteristics of the irregular variations of red supergiants (RSGs) are studied based on the RSG samples in Small Magellanic Cloud (SMC), Large Magellanic Cloud (LMC) and M31. With the time-series data from All-Sky…

Solar and Stellar Astrophysics · Physics 2020-07-29 Yi Ren , B. W. Jiang

Solar irradiance models that assume solar irradiance variations to be due to changes in the solar surface magnetic flux have been successfully used to reconstruct total solar irradiance on rotational as well as cyclical and secular time…

Solar and Stellar Astrophysics · Physics 2015-06-03 Yvonne C. Unruh , Will T. Ball , Natalie A. Krivova

Aims: We test the reliability of the observed and calculated spectral irradiance variations between 200 and 1600 nm over a time span of three solar rotations in 2004. Methods: We compare our model calculations to spectral irradiance…

Astrophysics · Physics 2009-11-13 Yvonne C. Unruh , Natalie A. Krivova , Sami K. Solanki , Jerald W. Harder , Greg Kopp

Radial-velocity (RV) signals induce RV variations an order of magnitude larger than the signal created by the orbit of Earth-twins, thus preventing their detection. The goal of this paper is to compare the efficiency of the different…

We demonstrate that for data recorded with a solar telescope that uses adaptive optics and/or post-processing to compensate for many low- and high-order aberrations, the RMS granulation contrast is directly proportional to the Strehl ratio…

Instrumentation and Methods for Astrophysics · Physics 2019-06-12 Goran Scharmer , Mats Lofdahl , Guus Sliepen , Jaime de la Cruz Rodriguez

Detecting small planets via the radial velocity method remains challenged by signals induced by stellar variability, versus the effects of the planet(s). Here, we explore using Gaussian Process (GP) regression with Transiting Exoplanet…

Solar contamination, due to moonlight and atmospheric scattering of sunlight, can cause systematic errors in stellar radial velocity (RV) measurements that significantly detract from the ~10cm/s sensitivity required for the detection and…

Simulating soil reflectance spectra is invaluable for soil-plant radiative modeling and training machine learning models, yet it is difficult as the intricate relationships between soil structure and its constituents. To address this, a…

Machine Learning · Computer Science 2024-05-03 Tong Lei , Brian N. Bailey

Hard X-ray spectra in solar flares provide knowledge of the electron spectrum that results from acceleration and propagation in the solar atmosphere. However, the inference of the electron spectra from solar X-ray spectra is an ill-posed…

Astrophysics · Physics 2009-11-10 E. P. Kontar , M. Piana , A. M. Massone , A. G. Emslie , J. C. Brown

Total solar irradiance and UV spectral solar irradiance have been monitored since 1978 through a succession of space missions. This is accompanied by the development of models aimed at replicating solar irradiance by relating the…

Solar and Stellar Astrophysics · Physics 2015-07-07 K. L. Yeo , W. T. Ball , N. A. Krivova , S. K. Solanki , Y. C. Unruh , J. Morrill

We investigate how rotationally-constrained, deep convection might give rise to supergranulation, the largest distinct spatial scale of convection observed in the solar photosphere. While supergranulation is only weakly influenced by…

Solar and Stellar Astrophysics · Physics 2016-10-19 Nicholas A. Featherstone , Bradley W. Hindman

In this contribution, we investigate the potential of hyperspectral data combined with either simulated ground penetrating radar (GPR) or simulated (sensor-like) soil-moisture data to estimate soil moisture. We propose two simulation…

Computer Vision and Pattern Recognition · Computer Science 2019-07-02 Felix M. Riese , Sina Keller

We present simulations of cumulus convection over land with shortwave radiation computed by a Monte Carlo ray tracer coupled to the flow solver. Ray tracing delivers very realistic in-cloud heating rates and global horizontal irradiance…

Atmospheric and Oceanic Physics · Physics 2023-01-04 Menno A. Veerman , Bart J. H. van Stratum , Chiel C. van Heerwaarden