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The distribution of galaxies, halo abundance, and peculiar velocities are influenced by non-linear gravitational interactions, making the study of non-linear evolution crucial for accurate cosmological predictions. We explore these aspects…

Cosmology and Nongalactic Astrophysics · Physics 2026-04-24 Swati Gavas

Understanding the nature and evolution of the photospheric helicity flux transfer is a key to reveal the role of magnetic helicity in coronal dynamics of solar active regions. Using SDO/HMI photospheric vector magnetograms and the derived…

Solar and Stellar Astrophysics · Physics 2017-01-11 P. Vemareddy , P. Démoulin

The SDO/HMI instruments provide photospheric vector magnetograms with a high spatial and temporal resolution. Our intention is to model the coronal magnetic field above active regions with the help of a nonlinear force-free extrapolation…

Solar and Stellar Astrophysics · Physics 2015-06-04 T. Wiegelmann , J. K. Thalmann , B. Inhester , T. Tadesse , X. Sun , J. T. Hoeksema

With the development of new instrumentation providing measurements of solar photospheric vector magnetic fields, we need to develop our understanding of the effects of current density on coronal magnetic field configurations. The object is…

Astrophysics · Physics 2009-11-13 S. Regnier , E. R. Priest

Quantifying coronal magnetic field remains a central problem in solar physics. Nowadays the coronal magnetic field is often modelled using nonlinear force-free field (NLFFF) reconstructions, whose accuracy has not yet been comprehensively…

Solar and Stellar Astrophysics · Physics 2018-09-14 Gregory D. Fleishman , Sergey Anfinogentov , Maria Loukitcheva , Ivan Mysh'yakov , Alexey Stupishin

The effects of sampling are investigated on measurements of counts-in-cells in three-dimensional magnitude limited galaxy surveys, with emphasis on moments of the underlying smooth galaxy density field convolved with a spherical window. A…

Astrophysics · Physics 2009-10-30 S. Colombi , I. Szapudi , A. S. Szalay

Investigation of propagation, conversion, and scattering of MHD waves in the Sun is very important for understanding the mechanisms of observed oscillations and waves in sunspots and active regions. We have developed 3D linear MHD numerical…

Astrophysics · Physics 2011-02-11 K. V. Parchevsky , A. G. Kosovichev

Time series of photospheric magnetic parameters of solar active regions (ARs) are used to answer whether scaling properties of fluctuations embedded in such time series help to distinguish between flare-quiet and flaring ARs. We examine a…

Solar and Stellar Astrophysics · Physics 2020-10-21 Eo-Jin Lee , Sung-Hong Park , Yong-Jae Moon

The effect of using two representations of the normal-to-surface magnetic field to calculate photospheric measures that are related to active region (AR) potential for flaring is presented. Several AR properties were computed using…

Solar and Stellar Astrophysics · Physics 2018-01-24 Jordan A. Guerra , Sung-H. Park , Ioannis Kontogiannis , Peter T. Gallagher , Manolis Georgoulis , D. Shaun Bloomfield

Extrapolation codes in Cartesian geometry for modelling the magnetic field in the corona do not take the curvature of the Sun's surface into account and can only be applied to relatively small areas, e.g., a single active region. We compare…

Solar and Stellar Astrophysics · Physics 2015-06-11 Tilaye Tadesse , T. Wiegelmann , B. Inhester , P. MacNeice , A. Pevtsov , X. Sun

Aims. We aim to develop a fast and consistent extrapolation method to model multiple layers of the solar atmosphere. Methods. The new approach combines the magnetohydrostatic (MHS) extrapolation which models the solar low atmosphere in a…

Solar and Stellar Astrophysics · Physics 2022-02-02 Xiaoshuai Zhu , Thomas Wiegelmann

Introduction: Long-term time series forecasting (LTSF) has gained significant attention in recent years. While various specialized designs exist for capturing temporal dependency, recent studies have shown that even a single linear layer…

Machine Learning · Computer Science 2026-05-19 Zhe Li , Shiyi Qi , Yiduo Li , Zenglin Xu

Solar flares create adverse space weather impacting space and Earth-based technologies. However, the difficulty of forecasting flares, and by extension severe space weather, is accentuated by the lack of any unique flare trigger or a single…

We developed Long Short-Term Memory (LSTM) models to predict the formation of active regions (ARs) on the solar surface. Using the Doppler shift velocity, the continuum intensity, and the magnetic field observations from the Solar Dynamics…

Solar and Stellar Astrophysics · Physics 2024-09-27 Spiridon Kasapis , Irina N. Kitiashvili , Alexander G. Kosovichev , John T. Stefan

This paper presents a closed-form analysis of spatial correlation and degrees of freedom (DoF) for arched holographic multiple-input multiple-output (HMIMO) arrays, which can be viewed as a special form of fluid antenna systems (FAS) when…

Systems and Control · Electrical Eng. & Systems 2025-09-17 Liuxun Xue , Shu Sun , Hangsong Yan

High-resolution spatial transcriptomics platforms, such as Xenium, generate single-cell images that capture both molecular and spatial context, but their extremely high dimensionality poses major challenges for representation learning and…

Solar flare simulations are commonly initialised using non-linear force free field (NLFF) extrapolations derived from photospheric vector magnetograms. However, the force free assumption neglects plasma forces and may limit the available…

Solar and Stellar Astrophysics · Physics 2026-05-15 W. Bate , M. Gordovskyy , A. Prasad , A. S. Brun , A. Strugarek , M. V. Sieyra , P. Browning , S. Inoue , K. Matsumoto , A. Roddanavar

For various applications, the relations between the dependent and independent variables are highly nonlinear. Consequently, for large scale complex problems, neural networks and regression trees are commonly preferred over linear models…

Machine Learning · Computer Science 2017-05-23 Samet Oymak , Mehrdad Mahdavi , Jiasi Chen

We analyse the spatial distribution of current helicity in solar active regions. A comparison of current helicity maps derived from three different instruments (Helioseismic and Magnetc Imager on board the Solar Dynamics Observatory,…

Solar and Stellar Astrophysics · Physics 2018-08-15 A. S. Kutsenko , V. I. Abramenko , K. M. Kuzanyan , Haiqing Xu , Hongqi Zhang

We propose an application of online hard sample mining for efficient training of Neural Radiance Fields (NeRF). NeRF models produce state-of-the-art quality for many 3D reconstruction and rendering tasks but require substantial…

Computer Vision and Pattern Recognition · Computer Science 2024-08-07 Juuso Korhonen , Goutham Rangu , Hamed R. Tavakoli , Juho Kannala