A closed-form formula for magnetic dipole localization by measurement of its magnetic field vector and magnetic gradient tensor

2020 ◽  
Vol 499 ◽  
pp. 166274 ◽  
Author(s):  
Gang Yin ◽  
Lin Zhang ◽  
Hong Jiang ◽  
Zhi Wei ◽  
Yan Xie
Keyword(s):  
Magnetic Field ◽  
Closed Form ◽  
Magnetic Dipole ◽  
Field Vector ◽  
Magnetic Field Vector ◽  
Dipole Localization ◽  
Gradient Tensor ◽  
Magnetic Gradient ◽  
Closed Form Formula

Closed-form formula of magnetic gradient tensor for a homogeneous polyhedral magnetic target: A tetrahedral grid example

Geophysics ◽  
2017 ◽  
Vol 82 (6) ◽  
pp. WB21-WB28 ◽  
Author(s):  
Zhengyong Ren ◽  
Chaojian Chen ◽  
Jingtian Tang ◽  
Huang Chen ◽  
Shuanggui Hu ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Closed Form ◽  
Magnetization Vector ◽  
Gradient Tensor ◽  
Magnetic Gradient ◽  
Closed Form Solutions ◽  
Tetrahedral Grid ◽  
Pipeline Model ◽  
The Magnetic Field ◽  
Closed Form Formula

A closed-form formula is developed for the full magnetic gradient tensor of a polyhedral body with a homogeneous magnetization vector. It is based on the direct derivative technique on the closed form of the magnetic field. These analytical expressions are implemented into an easy-to-use C++ package which simultaneously calculates the magnetic potential, the magnetic field, and the full magnetic gradient tensor for magnetic targets. Modern unstructured tetrahedral grids are adopted to represent the polyhedral body so that our code can deal with arbitrarily complicated magnetic targets. A prismatic body is tested to verify the accuracies of our closed-form formula. Excellent agreements are obtained between our closed-form solutions and solutions of a prismatic magnetic body with differences up to machine precision. A pipeline model is used to demonstrate its capability to deal with complicated magnetic targets. This C++ code is freely available to the magnetic exploration community.

Magnetic dipole localization based on magnetic gradient tensor data at a single point

2014 ◽  
Vol 8 (1) ◽  
pp. 083596 ◽  
Author(s):  
Yin Gang ◽  
Zhang Yingtang ◽  
Fan Hongbo ◽  
Li Zhining
Keyword(s):  
Magnetic Dipole ◽  
Single Point ◽  
Dipole Localization ◽  
Gradient Tensor ◽  
Magnetic Gradient ◽  
Tensor Data

Measurement of Cardiac Magnetic Field Vector

1989 ◽  
pp. 425-428 ◽  
Author(s):  
Y. Sakauchi ◽  
H. Kado ◽  
N. Awano ◽  
N. Kasai ◽  
M. Higuchi ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Field Vector ◽  
Magnetic Field Vector

scholarly journals Evaluation of Murrell’s EKF-Based Attitude Estimation Algorithm for Exploiting Multiple Attitude Sensor Configurations

Sensors ◽  
2021 ◽  
Vol 21 (19) ◽  
pp. 6450
Author(s):  
Sharanabasaweshwara Asundi ◽  
Norman Fitz-Coy ◽  
Haniph Latchman
Keyword(s):  
Magnetic Field ◽  
Time Derivative ◽  
Estimation Algorithm ◽  
Field Vector ◽  
Attitude Estimation ◽  
Magnetic Field Vector ◽  
Sun Sensor ◽  
Satellite Attitude ◽  
Multiple Sensor ◽  
Sensor Suite

Pico- and nano-satellites, due to their form factor and size, are limited in accommodating multiple or redundant attitude sensors. For such satellites, Murrell’s implementation of the extended Kalman filter (EKF) can be exploited to accommodate multiple sensor configurations from a set of non redundant attitude sensors. The paper describes such an implementation involving a sun sensor suite and a magnetometer as attitude sensors. The implementation exploits Murrell’s EKF to enable three sensor configurations, which can be operationally commanded, for satellite attitude estimation. Among the three attitude estimation schemes, (i) sun sensor suite and magnetometer, (ii) magnetic field vector and its time derivative and (iii) magnetic field vector, it is shown that the third configuration is better suited for attitude estimation in terms of precision and accuracy, but can consume more time to converge than the other two.

scholarly journals Improvement of the Helioseismic and Magnetic Imager (HMI) Vector Magnetic Field Inversion Code

2021 ◽  
Vol 923 (1) ◽  
pp. 84
Author(s):  
Ana Belén Griñón-Marín ◽  
Adur Pastor Yabar ◽  
Yang Liu ◽  
J. Todd Hoeksema ◽  
Aimee Norton
Keyword(s):  
Magnetic Field ◽  
Field Vector ◽  
Magnetic Field Vector ◽  
Solar Dynamics Observatory ◽  
Filling Fraction ◽  
Resolution Element ◽  
New Strategy ◽  
Moderate Field ◽  
Solar Dynamics ◽  
Field Strengths

Abstract A spectral line inversion code, Very Fast Inversion of the Stokes Vector (VFISV), has been used since 2010 May to infer the solar atmospheric parameters from the spectropolarimetric observations taken by the Helioseismic and Magnetic Imager (HMI) on board the Solar Dynamics Observatory. The magnetic filling factor, the fraction of the surface with a resolution element occupied by magnetic field, is set to have a constant value of 1 in the current version of VFISV. This report describes an improved inversion strategy for the spectropolarimetric data observed with HMI for magnetic field strengths of intermediate values in areas spatially not fully resolved. The VFISV inversion code has been modified to enable inversion of the Stokes profiles with two different components: one magnetic and one nonmagnetic. In this scheme, both components share the atmospheric components except for the magnetic field vector. In order to determine whether the new strategy is useful, we evaluate the inferred parameters inverted with one magnetic component (the original version of the HMI inversion) and with two components (the improved version) using a Bayesian analysis. In pixels with intermediate magnetic field strengths (e.g., plages), the new version provides statistically significant values of filling fraction and magnetic field vector. Not only does the fitting of the Stokes profile improve, but also the inference of the magnetic parameters and line-of-sight velocity are obtained uniquely. The new strategy is also proven to be effective for mitigating the anomalous hemispheric bias in the east–west magnetic field component in moderate field regions.

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