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Utilizing data from the $Solar$ $Magnetism$ and $Activity$ $Telescope$ (SMAT), analytical solutions of polarized radiative transfer equations, and in-orbit test data from the Full-disk Magnetograph (FMG) onboard the Advanced Space based…

Solar and Stellar Astrophysics · Physics 2024-05-28 S. Liu , J. T. Su , X. Y. Bai , Y. Y. Deng , J. Chen , Y. L. Song , X. F. Wang , H. Q. Xu , X. Yang , Shahid Idrees

Zeeman observations provide the only direct probe of line-of-sight (LOS) magnetic fields in the interstellar medium. To evaluate their accuracy and limitations, we generate synthetic HI Zeeman spectra from magnetohydrodynamic simulations…

Astrophysics of Galaxies · Physics 2026-02-24 Duo Xu , Peter Martin , Stella Offner , Robert Gutermuth , Michael Grudic , Joshua Speagle

We present an automated system for detecting, tracking, and cataloging emerging active regions throughout their evolution and decay using SOHO Michelson Doppler Interferometer (MDI) magnetograms. The SolarMonitor Active Region Tracking…

Solar and Stellar Astrophysics · Physics 2010-07-01 Paul A. Higgins , Peter T. Gallagher , R. T. James McAteer , D. Shaun Bloomfield

State of the art radial velocity (RV) exoplanet searches are limited by the effects of stellar magnetic activity. Magnetically active spots, plage, and network regions each have different impacts on the observed spectral lines, and…

In this work we present a practical algorithm for calibrating a magnetometer for the presence of magnetic disturbances and for magnetometer sensor errors. To allow for combining the magnetometer measurements with inertial measurements for…

Systems and Control · Computer Science 2016-07-15 Manon Kok , Thomas B. Schön

Sensorless control of Permanent-Magnet Synchronous Motors (PMSM) at low velocity remains a challenging task. A now well-established method consists in injecting a high-frequency signal and use the rotor saliency, both geometric and…

Optimization and Control · Mathematics 2012-07-25 Al Kassem Jebai , Francois Malrait , Philippe Martin , Pierre Rouchon

In the past, spectropolarimetric data from Hinode/SP has been employed to infer the distribution of the magnetic field vector in the quiet Sun. While some authors have found predominantly horizontal magnetic fields, others favor an…

Solar and Stellar Astrophysics · Physics 2015-05-20 J. M. Borrero , P. Kobel

A steradian of the southern sky has been imaged at 151.5 MHz using the Mauritius Radio Telescope (MRT). These images show systematics in positional errors of sources when compared to source positions in the Molonglo Reference Catalogue…

Instrumentation and Methods for Astrophysics · Physics 2015-05-19 Arvind Nayak , Soobash Daiboo , N. Udaya Shankar

Radio frequency (RF) spike noise is a common source of exogenous image corruption in MRI. Spikes occur as point-like disturbances of $k$-space that lead to global sinusoidal intensity errors in the image domain. Depending on the amplitude…

Medical Physics · Physics 2021-12-01 David S. Smith , Joel Kullberg , Johan Berglund , Malcolm J. Avison , E. Brian Welch

High-contrast imaging of extrasolar planet candidates around a main-sequence star has recently been realized from the ground using current adaptive optics (AO) systems. Advancing such observations will be a task for the Gemini Planet…

Instrumentation and Methods for Astrophysics · Physics 2010-11-02 Katie Morzinski , Bruce Macintosh , Donald Gavel , Daren Dillon

The Zeeman effect is of limited utility for probing the magnetism of the quiet solar chromosphere. The Hanle effect in some spectral lines is sensitive to such magnetism, but the interpretation of the scattering polarization signals…

Solar and Stellar Astrophysics · Physics 2021-04-21 Jan Jurcak , Jiri Stepan , Javier Trujillo Bueno

The polarised spectrum of stellar radiation encodes valuable information on the conditions of stellar atmospheres and the magnetic fields that permeate them. In this paper, we give explicit expressions to estimate the magnetic field vector…

Solar and Stellar Astrophysics · Physics 2015-05-30 M. J. Martínez González , R. Manso Sainz , A. Asensio Ramos , L. Belluzzi

The Mauritius Radio Telescope (MRT) images show systematics in the positional errors of sources when compared to source positions in the Molonglo Reference Catalogue (MRC). We have applied two-dimensional homography to correct positional…

Instrumentation and Methods for Astrophysics · Physics 2009-05-07 Arvind Nayak , Soobash Daiboo , N. Udaya Shankar

Dust polarization orientations in molecular clouds often tend to be close to tangential to the Stokes $I$ dust continuum emission contours. The magnetic field and the emission gradient orientations, therefore, show some correlation. A…

Astrophysics of Galaxies · Physics 2015-06-03 Patrick M. Koch , Ya-Wen Tang , Paul T. P. Ho

The Sun's magnetic field is strongly structured over a broad range of scales. The magnetic spatial power spectral analysis provides a powerful tool to understand the various scales of magnetic fields and their interaction with plasma…

Solar and Stellar Astrophysics · Physics 2023-08-16 Yukun Luo , Jie Jiang , Ruihui Wang

We carried out the Stokes diagnostics of new two-dimensional magnetohydrodynamic models with a continuous evolution of magnetogranulation in the course of two hours of the hydrodynamic (solar) time. Our results agree satisfactorily with the…

Solar and Stellar Astrophysics · Physics 2012-10-25 V. A. Sheminova

We consider the problem of high-dimensional channel estimation in fast time-varying millimeter-wave MIMO systems with a hybrid architecture. By exploiting the low-rank and sparsity properties of the channel matrix, we propose a two-phase…

Signal Processing · Electrical Eng. & Systems 2025-11-04 Tianyu Jiang , Yan Yang , Hongjin Liu , Runyu Han , Bo Ai , Mohsen Guizani

The magnetic fields in the solar polar region are important to our understanding of the internal dynamo process, the global coronal structure, and the origin of the solar wind. The inference of polar fields based on spectropolarimetric…

Solar and Stellar Astrophysics · Physics 2026-03-16 Bryan Yamashiro , Xudong Sun , Ivan Milić , Carlos Quintero Noda , Adur Pastor Yabar , Rebecca Centeno , Jiayi Liu , Milan Gošić , Kai Yang

The spectral window, containing Fraunhofer lines formed in the solar photosphere, around the magnetically sensitive Cr I lines at 5780.9, 5781.1, 5781.7, 5783.0, and 5783.8 \r{A}, with Land\'e g-factors between 1.6 and 2.5, is explored. The…

Background: Magnetization transfer (MT) saturation reflects the additional saturation of the MRI signal imposed by an MT pulse and is largely driven by the saturation of the bound pool. This reduction of the bound polarization by the MT…

Medical Physics · Physics 2021-05-03 Gunther Helms , Nikolaus Weiskopf , Antoine Lutti