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A pseudo-spectral method with an absorbing outer boundary is used to solve a set of the time-dependent force-free equations. In the method, both electric and magnetic fields are expanded in terms of the vector spherical harmonic (VSH)…

High Energy Astrophysical Phenomena · Physics 2015-12-16 Gang Cao , Li Zhang , Sineng Sun

We aim at demonstrating the capabilities of a newly developed method for determining electric currents in the solar photosphere. We employ three-dimensional radiative magneto-hydrodynamic (MHD) simulations to produce synthetic Stokes…

Solar and Stellar Astrophysics · Physics 2021-12-22 A. Pastor Yabar , J. M. Borrero , C. Quintero Noda , B. Ruiz Cobo

This work is concerned with optical imaging in strongly diffusive environments. We consider a typical setting in optical coherence tomography where a sample is probed by a collection of wavefields produced by a laser and propagating through…

Optics · Physics 2024-12-10 Randy Bartels , Olivier Pinaud , Maxine Varughese

We present a novel method to search for structures of coherently aligned patterns in ultra-high energy cosmic-ray arrival directions simultaneously across the entire sky. This method can be used to obtain information on the Galactic…

Instrumentation and Methods for Astrophysics · Physics 2022-01-31 Marcus Wirtz , Teresa Bister , Martin Erdmann

Optical aberrations prevent telescopes from reaching their theoretical diffraction limit. Once estimated, these aberrations can be compensated for using deformable mirrors in a closed loop. Focal plane wavefront sensing enables the…

In quantum sensing of magnetic fields, ensembles of nitrogen-vacancy centers in diamond offer high sensitivity, high bandwidth and outstanding spatial resolution while operating in harsh environments. Moreover, the orientation of defect…

We retrieve depth information (moments) of an object using partially coherent fields and defocus induced holographic contrast. Our analysis leads to a form of tomography that does not require sample or source rotation. The tomography method…

Optics · Physics 2016-06-22 M. A. Beltran , T. C. Petersen , M. J. Kitchen , D. M. Paganin

This paper presents a new method for learning dissipative Hamiltonian dynamics from a limited and noisy dataset. The method uses the Helmholtz decomposition to learn a vector field as the sum of a symplectic and a dissipative vector field.…

Machine Learning · Computer Science 2025-03-18 Torbjørn Smith , Olav Egeland

As established in previous papers of this series, observables in highly distorted and magnified multiple images caused by the strong gravitational lensing effect can be used to constrain the distorting properties of the gravitational lens…

Cosmology and Nongalactic Astrophysics · Physics 2022-09-21 Joyce Lin , Jenny Wagner , Richard E. Griffiths

In order to assure a stable series of recorded images of sufficient quality for further scientific analysis, an objective image quality measure is required. Especially when dealing with ground-based observations, which are subject to…

Solar and Stellar Astrophysics · Physics 2020-11-11 Robert Jarolim , Astrid Veronig , Werner Pötzi , Tatiana Podladchikova

Reliable and exact assessment of visibility is essential for safe air traffic. In order to overcome the drawbacks of the currently subjective reports from human observers, we present an approach to automatically derive visibility measures…

Computer Vision and Pattern Recognition · Computer Science 2015-05-21 Jean-Philippe Andreu , Stefan Mayer , Karlheinz Gutjahr , Harald Ganster

A technique is proposed for constructing three-dimensional solutions comlplying with the self-consistent magnetohydrostatic (MHS) equations and with observations along the line of sight of the magnetic field at the photosphere. The…

Astrophysics · Physics 2009-10-31 G. V. Rudenko

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

To ensure energy efficiency and reliable operations, it is essential to monitor solar panels in generation plants to detect defects. It is quite labor-intensive, time consuming and costly to manually monitor large-scale solar plants and…

Computer Vision and Pattern Recognition · Computer Science 2026-04-14 Muhammad Junaid Asif , Muhammad Saad Rafaqat , Usman Nazakat , Uzair Khan , Rana Fayyaz Ahmad

Let $X$ be a Hamiltonian vector field defined on a symplectic manifold $(M,\omega)$, $g$ a nowhere vanishing smooth function defined on an open dense subset $M^0$ of $M$. We will say that the vector field $Y = gX$ is conformally…

Symplectic Geometry · Mathematics 2011-02-22 Charles-Michel Marle

We find conditions under which the restriction of a divergence-free vector field $B$ to an invariant toroidal surface $S$ is linearisable. The main results are similar in conclusion to Arnold's Structure Theorems but require weaker…

Differential Geometry · Mathematics 2022-03-09 David Perrella , David Pfefferlé , Luchezar Stoyanov

Nitrogen-Vacancy (NV) centers in diamond have useful properties for detecting both AC and DC magnetic fields with high sensitivity at nano-scale resolution. Vector detection of AC magnetic fields can be achieved by using NV centers having…

Quantum Physics · Physics 2026-01-13 Pooja Lamba , Akshat Rana , Sougata Halder , Siddharth Dhomkar , Dieter Suter , Rama K. Kamineni

We develop a formalism wherein the solution of the equations of equilibrium for a self-gravitating, magnetized interstellar cloud may be accomplished analytically, under the only hypotheses that (a) the cloud is scale-free, and (b) is…

Astrophysics · Physics 2007-05-23 Daniele Galli

Focusing waves inside inhomogeneous media is a fundamental problem for imaging. Spatial variations of wave velocity can strongly distort propagating wavefronts and degrade image quality. Adaptive focusing can compensate for such aberration,…

Image and Video Processing · Electrical Eng. & Systems 2020-06-15 William Lambert , Laura A. Cobus , Thomas Frappart , Mathias Fink , Alexandre Aubry

Magnetic helicity is a key geometrical parameter to describe the structure and evolution of solar coronal magnetic fields. The accumulation of magnetic helicity is correlated with the non-potential magnetic field energy, which is released…

Solar and Stellar Astrophysics · Physics 2024-12-25 Shangbin Yang , Suo Liu , Jiangtao Su , Yuanyong Deng