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The finite-element analysis of three-dimensional magnetostatic problems in terms of magnetic vector potential has proven to be one of the most efficient tools capable of providing the excellent quality results but becoming computationally…

Computational Physics · Physics 2023-07-25 Alexander Chervyakov

Nonnegative matrix factorization (NMF) has become a very popular technique in machine learning because it automatically extracts meaningful features through a sparse and part-based representation. However, NMF has the drawback of being…

Machine Learning · Statistics 2012-12-07 Nicolas Gillis

We investigate the recently quantified misalignment of $\alpha_{mis} \approx 20^\circ-40^\circ$ between the 3-D geometry of stereoscopically triangulated coronal loops observed with STEREO/EUVI (in four active regions) and theoretical…

Solar and Stellar Astrophysics · Physics 2015-05-18 Markus J. Aschwanden , Anne W. Sandman

Nonnegative Matrix Factorization (NMF) is an important unsupervised learning method to extract meaningful features from data. To address the NMF problem within a polynomial time framework, researchers have introduced a separability…

Machine Learning · Computer Science 2025-01-23 Juefei Chen , Longxiu Huang , Yimin Wei

The multislice method, which simulates the propagation of the incident electron wavefunction through a crystal, is a well-established method for analyzing the multiple scattering effects that an electron beam may undergo. The inclusion of…

Materials Science · Physics 2021-05-11 Keenan Lyon , Jan Rusz

Photon loss rates set an effective upper limit on the size of computations that can be run on current linear optical quantum devices. We present a family of techniques designed to mitigate the effects of photon loss on both output…

Quantum Physics · Physics 2026-03-18 James Mills , Rawad Mezher

We consider a set of M images, whose pixel intensities at a common point can be treated as the components of a M-dimensional vector. We are interested in the estimation of the modulus of such a vector associated to a compact source. For…

Cosmology and Nongalactic Astrophysics · Physics 2011-01-05 F. Argueso , J. L. Sanz , D. Herranz

In this paper, a potential field extrapolation and three nonlinear force-free (NLFF) field extrapolations (optimization, direct boundary integral (DBIE) and approximate vertical integration (AVI) methods) are used to study the spatial…

Solar and Stellar Astrophysics · Physics 2014-05-12 Liu S. , Zhang H. Q. , Su J. T

We introduce NPEFF (Non-Negative Per-Example Fisher Factorization), an interpretability method that aims to uncover strategies used by a model to generate its predictions. NPEFF decomposes per-example Fisher matrices using a novel…

Machine Learning · Computer Science 2025-05-12 Michael Matena , Colin Raffel

The realization of optical non-reciprocity is crucial for many device applications, and also of fundamental importance for manipulating and protecting the photons with desired time-reversal symmetry. Recently, various new mechanisms of…

Preconditioning is a key component of MCMC algorithms that improves sampling efficiency by facilitating exploration of geometrically complex target distributions through an invertible map. While linear preconditioners are often sufficient…

Machine Learning · Computer Science 2025-11-05 David Nabergoj , Erik Štrumbelj

The solar active region (AR) 12192 was one of the most flare productive region of solar cycle 24, which produced many X-class flares; the most energetic being an X3.1 flare on October 24, 2014 at 21:10 UT. Customarily, such events are…

Solar and Stellar Astrophysics · Physics 2019-01-30 A. Prasad , R. Bhattacharyya , Q. Hu , S. S. Nayak , Sanjay Kumar

The coronal magnetic field plays a fundamental role in governing coronal activities, driving space-weather events, and shaping the heliosphere. Due to a lack of direct observations, extrapolation models such as the Potential Field Source…

Solar and Stellar Astrophysics · Physics 2026-04-02 Ziqi Wu , Jiansen He , Chuanpeng Hou , Tom van Doorsselaere , Rui Zhuo , Tianhang Chen , Liping Yang , David Pontin , Daniel Verscharen , Fang Shen

We present a Python code for calculating and displaying magnetic field extrapolations from given two-dimensional boundary conditions, specifically from solar surface magnetograms. The code implements analytical magnetohydrostatic models…

Solar and Stellar Astrophysics · Physics 2025-11-13 Lilli Nadol , Thomas Neukirch

Photospheric magnetic vector maps from two different instruments are used to model the nonlinear force-free coronal magnetic field above an active region. We use vector maps inferred from polarization measurements of the Solar Dynamics…

Solar and Stellar Astrophysics · Physics 2015-06-15 J. K. Thalmann , S. K. Tiwari , T. Wiegelmann

Force-free extrapolations are widely used to study the magnetic field in the solar corona based on surface measurements. The extrapolations assume that the ratio of internal energy of the plasma to magnetic energy, the plasma-beta is…

Solar and Stellar Astrophysics · Physics 2015-11-25 H. Peter , J. Warnecke , L. P. Chitta , R. H. Cameron

Photospheric electric fields, estimated from sequences of vector magnetic field and Doppler measurements, can be used to estimate the flux of magnetic energy (the Poynting flux) into the corona and as time-dependent boundary conditions for…

Solar and Stellar Astrophysics · Physics 2014-10-13 Maria D. Kazachenko , George H. Fisher , Brian T. Welsch

The signal resulting from magnetic resonance spectroscopy is occupied by noises and irregularities so in the further analysis preprocessing techniques have to be introduced. The main idea of the paper is to develop a model of a signal as a…

Signal Processing · Electrical Eng. & Systems 2021-03-30 Michał Staniszewski , Andrzej Polański

Nonnegative matrix factorization (NMF) is a linear dimensionality reduction technique for nonnegative data, with applications such as hyperspectral unmixing and topic modeling. NMF is a difficult problem in general (NP-hard), and its…

Numerical Analysis · Mathematics 2025-11-11 Junjun Pan , Valentin Leplat , Michael Ng , Nicolas Gillis

In micromagnetic simulations, the demagnetization field is by far the computationally most expensive field component and often a limiting factor in large multilayer systems. We present an exact method to calculate the demagnetization field…

Computational Physics · Physics 2020-03-18 Paul Heistracher , Florian Bruckner , Claas Abert , Christoph Vogler , Dieter Suess
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