An Improved MFL Method Fusing Multi-Space Magnetic Field Information for The Surface Defect Inspecting

Author(s):  
Wenzhi Wang ◽  
Songling Huang ◽  
Lisha Peng ◽  
Yue Long ◽  
Shen Wang ◽  
...  
2020 ◽  
Vol 10 ◽  
pp. 41 ◽  
Author(s):  
Yoichiro Hanaoka ◽  
Takashi Sakurai ◽  
Ken’ichi Otsuji ◽  
Isao Suzuki ◽  
Satoshi Morita

The solar group at the National Astronomical Observatory of Japan is conducting synoptic solar observation with the Solar Flare Telescope. While it is a part of a long-term solar monitoring, contributing to the study of solar dynamo governing solar activity cycles, it is also an attempt at contributing to space weather research. The observations include imaging with filters for Hα, Ca K, G-band, and continuum, and spectropolarimetry at the wavelength bands including the He I 1083.0 nm/Si I 1082.7 nm and the Fe I 1564.8 nm lines. Data for the brightness, Doppler signal, and magnetic field information of the photosphere and the chromosphere are obtained. In addition to monitoring dynamic phenomena like flares and filament eruptions, we can track the evolution of the magnetic fields that drive them on the basis of these data. Furthermore, the magnetic field in solar filaments, which develops into a part of the interplanetary magnetic cloud after their eruption and occasionally hits the Earth, can be inferred in its pre-eruption configuration. Such observations beyond mere classical monitoring of the Sun will hereafter become crucially important from the viewpoint of the prediction of space weather phenomena. The current synoptic observations with the Solar Flare Telescope is considered to be a pioneering one for future synoptic observations of the Sun with advanced instruments.


2021 ◽  
Author(s):  
Veronika Haberle ◽  
Aurélie Marchaudon ◽  
Pierre-Louis Blelly ◽  
Aude Chambodut

<p>The Earth’s magnetic field as measured from ground-based magnetometers is composed of a variety of fields generated by diverse sources, spanning a broad amplitude and frequency spectrum. Long-term variable sources induce smooth changes, whereas short-term variable sources are able to induce rapid spikes in the geomagnetic field. An important aspect of Space Weather research is to understand the contribution and impact of each of these sources. In particular, knowing the amplitude and frequency of steady-like sources, like diurnal variations, enables us to determine the impact of sudden and hazardous events such as solar storms. The basic approach to this challenge is to identify the quiet magnetic field information within the recorded time-varying signal.<br>In this work, we examine the variance of the magnetically quiet diurnal and semi-diurnal components of the geomagnetic field, as recorded by ground-based magnetic observatories of the INTERMAGNET network. These variations are extracted by applying appropriately designed digital filters on the geomagnetic field time series. The residual signal is analysed in terms of local time and seasonal variations for selected locations under quiet magnetic conditions. This approach allows us to evaluate the applicability of the introduced filtering method. The obtained results improve our understanding of the driving sources of quiet currents such as the Sq current and the variations of their distributions with respect to regular solar irradiance variations. They will also contribute to a better extraction and description of the remaining/residual signal related to solar wind stimuli (e.g. ICMEs, CIRs) causing magnetic storms.</p>


2007 ◽  
Vol 274 (1614) ◽  
pp. 1153-1158 ◽  
Author(s):  
Todd E Dennis ◽  
Matt J Rayner ◽  
Michael M Walker

The influence of the Earth's magnetic field on locomotory orientation has been studied in many taxa but is best understood for homing pigeons ( Columba livia ). Effects of experimentally induced and naturally occurring perturbations in the geomagnetic field suggest that pigeons are sensitive to changes in geomagnetic parameters. However, whether pigeons use the Earth's magnetic field for position determination remains unknown. Here we report an apparent orientation to the intensity gradient of the geomagnetic field observed in pigeons homing from sites in and around a magnetic anomaly. From flight trajectories recorded by GPS-based tracking devices, we noted that many pigeons released at unfamiliar sites initially flew, in some cases up to several kilometres, in directions parallel and/or perpendicular to the bearing of the local intensity field. This behaviour occurred irrespective of the homeward direction and significantly more often than what was expected by random chance. Our study describes a novel behaviour which provides strong evidence that pigeons when homing detect and respond to spatial variation in the Earth's magnetic field—information of potential use for navigation.


Galaxies ◽  
2019 ◽  
Vol 7 (2) ◽  
pp. 45 ◽  
Author(s):  
Amit Seta ◽  
Rainer Beck

Energy equipartition between cosmic rays and magnetic fields is often assumed to infer magnetic field properties from the synchrotron observations of star-forming galaxies. However, there is no compelling physical reason to expect the same. We aim to explore the validity of the energy equipartition assumption. After describing popular arguments in favour of the assumption, we first discuss observational results that support it at large scales and how certain observations show significant deviations from equipartition at scales smaller than ≈ 1 kpc , probably related to the propagation length of the cosmic rays. Then, we test the energy equipartition assumption using test-particle and magnetohydrodynamic (MHD) simulations. From the results of the simulations, we find that the energy equipartition assumption is not valid at scales smaller than the driving scale of the ISM turbulence (≈ 100 pc in spiral galaxies), which can be regarded as the lower limit for the scale beyond which equipartition is valid. We suggest that one must be aware of the dynamical scales in the system before assuming energy equipartition to extract magnetic field information from synchrotron observations. Finally, we present ideas for future observations and simulations to investigate in more detail under which conditions the equipartition assumption is valid or not.


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