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The nonlinear force-free field (NLFFF) modeling has been extensively used to infer the three-dimensional (3D) magnetic field in the solar corona. One of the assumptions in the NLFFF extrapolation is that the plasma beta is low, but this…

Solar and Stellar Astrophysics · Physics 2020-07-30 Yusuke Kawabata , Andrés Asensio Ramos , Satoshi Inoue , Toshifumi Shimizu

The shapes of solar coronal loops are sensitive to the presence of electrical currents that are the carriers of the nonpotential energy available for impulsive activity. We use this information in a new method for modeling the coronal…

Solar and Stellar Astrophysics · Physics 2021-06-29 A. Malanushenko , C. Schrijver , M. L. DeRosa , M. S. Wheatland

Due to the absence of direct measurement, the magnetic field in the solar corona is usually extrapolated from the photosphere in numerical way. At the moment, the nonlinear force-free field (NLFFF) model dominates the physical models for…

Solar and Stellar Astrophysics · Physics 2015-06-15 Chaowei Jiang , Xueshang Feng

The inspection of local flaws (LFs) in Steel Wire Ropes (SWRs) is crucial for ensuring safety and reliability in various industries. Magnetic Flux Leakage (MFL) imaging is commonly used for non-destructive testing, but its effectiveness is…

Image and Video Processing · Electrical Eng. & Systems 2025-03-17 Siyu You , Huayi Gou , Leilei Yang , Zhiliang Liu , Mingjian Zuo

The nonlinear force-free field (NLFFF) modeling has been extensively used as a tool to infer three-dimensional (3D) magnetic field structure. In this study, the dependency of the NLFFF calculation with respect to the initial guess of the 3D…

Solar and Stellar Astrophysics · Physics 2020-06-09 Y. Kawabata , S. Inoue , T. Shimizu

Functional magnetic resonance imaging (fMRI) data contain complex spatiotemporal dynamics, thus researchers have developed approaches that reduce the dimensionality of the signal while extracting relevant and interpretable dynamics. Models…

Computer Vision and Pattern Recognition · Computer Science 2022-05-30 Eloy Geenjaar , Amrit Kashyap , Noah Lewis , Robyn Miller , Vince Calhoun

In this study, photospheric vector magnetograms obtained with the Synoptic Optical Long-term Investigations of the Sun survey (SOLIS), are used as boundary conditions to model the three-dimensional nonlinear force-free (NLFF) coronal…

Solar and Stellar Astrophysics · Physics 2015-05-30 Tilaye Tadesse , T. Wiegelmann , B. Inhester , A. Pevtsov

We study five sequential solar flares (SOL2015-08-07) occurring in Active Region 12396 observed with the Goode Solar Telescope (GST) at the BBSO, complemented by IRIS and SDO observations. The main flaring region is an arch filament system…

Solar and Stellar Astrophysics · Physics 2018-03-19 Yingna Su , Rui Liu , Shangwei Li , Wenda Cao , Kwangsu Ahn , Haisheng Ji

Active contour models have achieved prominent success in the area of image segmentation, allowing complex objects to be segmented from the background for further analysis. Existing models can be divided into region-based active contour…

Computer Vision and Pattern Recognition · Computer Science 2022-05-24 Ehtesham Iqbal , Asim Niaz , Asif Aziz Memon , Usman Asim , Kwang Nam Choi

The magnetic field permeating the solar atmosphere is generally thought to provide the energy for much of the activity seen in the solar corona, such as flares, coronal mass ejections (CMEs), etc. To overcome the unavailability of coronal…

Solar and Stellar Astrophysics · Physics 2015-06-17 Tilaye Tadesse , T. Wiegelmann , S. Gosain , P. MacNeice , Alexei A. Pevtsov

Context. Magnetic helicity is a physical quantity of great importance in the study of astrophysical and natural plasmas. Although a density for helicity cannot be defined, a good proxy for it is field line helicity. The appropriate quantity…

Solar and Stellar Astrophysics · Physics 2021-05-26 K. Moraitis , S. Patsourakos , A. Nindos

A more accurate analytical solution of the {\sl vertical-current approximation nonlinear force-free field (VCA3-NLFFF)} model is presented that includes besides the radial $(B_r)$ and the azimuthal $(B_\varphi)$ magnetic field components a…

Solar and Stellar Astrophysics · Physics 2020-01-08 Markus J. Aschwanden

Functional magnetic resonance imaging (fMRI) is a neuroimaging technique known for its ability to capture brain activity non-invasively and at fine spatial resolution (2-3mm). Cortical surface fMRI (cs-fMRI) is a recent development of fMRI…

Applications · Statistics 2023-12-29 Huy Dang , Marzia Cremona , Nicole Lazar , Francesca Chiaromonte

In the quiet solar photosphere, the mixed polarity fields form a magnetic carpet, which continuously evolves due to dynamical interaction between the convective motions and magnetic field. This interplay is a viable source to heat the solar…

Solar and Stellar Astrophysics · Physics 2014-09-16 L. P. Chitta , R. Kariyappa , A. A. van Ballegooijen , E. E. DeLuca , S. K. Solanki

Human activity recognition (HAR) ideally relies on data from wearable or environment-instrumented sensors sampled at regular intervals, enabling standard neural network models optimized for consistent time-series data as input. However,…

Signal Processing · Electrical Eng. & Systems 2025-01-28 Mengxi Liu , Daniel Geißler , Sizhen Bian , Bo Zhou , Paul Lukowicz

It is generally believed that the evolution of magnetic helicity has a close relationship with solar activity. Before the launch of SDO, earlier studies have mostly used MDI/SOHO line of sight magnetograms and assumed that magnetic fields…

Solar and Stellar Astrophysics · Physics 2015-05-20 Yongliang Song , Mei Zhang

Magnetic field extrapolation is an important tool to study the three-dimensional (3D) solar coronal magnetic field which is difficult to directly measure. Various analytic models and numerical codes exist but their results often drastically…

Solar and Stellar Astrophysics · Physics 2017-06-28 Aiying Duan , Chaowei Jiang , Qiang Hu , Huai Zhang , G. Allen Gary , S. T. Wu , Jinbin Cao

We derive an analytical approximation of nonlinear force-free magnetic field solutions (NLFFF) that can efficiently be used for fast forward-fitting to solar magnetic data, constrained either by observed line-of-sight magnetograms and…

Solar and Stellar Astrophysics · Physics 2014-03-27 Markus J. Aschwanden

We develop a nonlinear force-free field (NLFFF) extrapolation code based on the magnetohydrodynamic (MHD) relaxation method. We extend the classical MHD relaxation method in two important ways. First, we introduce an algorithm initially…

Solar and Stellar Astrophysics · Physics 2015-06-17 S. Inoue , T. Magara , V. S. Pandey , D. Shiota. , K. Kusano , G. S. Choe , K. S. Kim

Models for the evolution of the solar coronal magnetic field are vital for understanding solar activity, yet the best measurements of magnetic field lie at the photosphere, necessitating the development of coronal models which are…

Solar and Stellar Astrophysics · Physics 2017-04-05 James E. Leake , Mark G. Linton , Peter W. Schuck