scholarly journals REDUCTION OF LEAKAGE MAGNETIC FIELD IN ELECTROMAGNETIC SYSTEMS BASED ON ACTIVE SHIELDING CONCEPT VERIFIED BY EIGENVALUE ANALYSIS

2009 ◽  
Vol 96 ◽  
pp. 217-236 ◽  
Author(s):  
Faramarz Faghihi ◽  
Hossein Heydari
Keyword(s):  
Magnetic Field ◽  
Eigenvalue Analysis ◽  
Leakage Magnetic Field ◽  
Active Shielding

Digital phase analysis in interference electron microscopy

1988 ◽  
Vol 46 ◽  
pp. 842-843
Author(s):  
S. Hasegawa ◽  
T. Kawasaki ◽  
J. Endo ◽  
M. Futamoto ◽  
A. Tonomura
Keyword(s):  
Magnetic Field ◽  
Electron Microscopy ◽  
Phase Distribution ◽  
Magnetic Recording Media ◽  
Electron Wave ◽  
Vector Potentials ◽  
Weak Magnetic Fields ◽  
Leakage Magnetic Field ◽  
Optical Reconstruction ◽  
Processing Techniques

Interference electron microscopy enables us to record the phase distribution of an electron wave on a hologram. The distribution is visualized as a fringe pattern in a micrograph by optical reconstruction. The phase is affected by electromagnetic potentials; scalar and vector potentials. Therefore, the electric and magnetic field can be reduced from the recorded phase. This study analyzes a leakage magnetic field from CoCr perpendicular magnetic recording media. Since one contour fringe interval corresponds to a magnetic flux of Φo(=h/e=4x10-15Wb), we can quantitatively measure the field by counting the number of finges. Moreover, by using phase-difference amplification techniques, the sensitivity for magnetic field detection can be improved by a factor of 30, which allows the drawing of a Φo/30 fringe. This sensitivity, however, is insufficient for quantitative analysis of very weak magnetic fields such as high-density magnetic recordings. For this reason we have adopted “fringe scanning interferometry” using digital image processing techniques at the optical reconstruction stage. This method enables us to obtain subfringe information recorded in the interference pattern.

METHOD OF SYNTHESIS OF CLOSED-LOOP SYSTEMS OF ACTIVE SHIELDING MAGNETIC FIELD OF POWER TRANSMISSION LINES

2016 ◽  
Vol 2016 (4) ◽  
pp. 8-10 ◽  
Author(s):  
B.I. Kuznetsov ◽  
◽  
A.N. Turenko ◽  
T.B. Nikitina ◽  
A.V. Voloshko ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Transmission Lines ◽  
Closed Loop ◽  
Power Transmission ◽  
Power Transmission Lines ◽  
Closed Loop Systems ◽  
Active Shielding

scholarly journals SYNTHESIS OF AN ACTIVE SHIELDING SYSTEM OF THE MAGNETIC FIELD OF POWER LINES BASED ON MULTIOBJECTIVE OPTIMIZATION

2016 ◽  
Vol 0 (6) ◽  
pp. 26-30 ◽  
Author(s):  
B. I. Kuznetsov ◽  
T. B. Nikitina ◽  
A. V. Voloshko ◽  
I. V. Bovdyj ◽  
E. V. Vinichenko ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Multiobjective Optimization ◽  
Power Lines ◽  
Active Shielding ◽  
The Magnetic Field ◽  
Shielding System

Eddy Current Loss and Shielding Research of the Tank in Power Transformer

2012 ◽  
Vol 468-471 ◽  
pp. 1086-1089 ◽  
Author(s):  
Yong Ming Xu ◽  
Chao Du ◽  
Da Wei Meng
Keyword(s):  
Magnetic Field ◽  
Eddy Current ◽  
Power Transformer ◽  
Element Model ◽  
Eddy Current Loss ◽  
Calculation Model ◽  
Ultrahigh Pressure ◽  
Tank Wall ◽  
Current Loss ◽  
Leakage Magnetic Field

The problem about the eddy current loss which is caused by leakage magnetic field in ultrahigh pressure large capacity power transformer is becoming more extrusive. It is very significant to research the power transformer leakage magnetic field and eddy current loss on the tank wall thoroughly and accurately. 3D finite element model of power transformer leakage magnetic field and eddy current loss is established in this paper, the eddy current loss on the tank wall is calculated and the distribution is analyzed. For the eddy current loss could be reduced by magnetic shielding, new calculation model are established respectively, then eddy current loss on tank wall could be got with shielding. The best size and location of the shielding could be analyzed after changing the height of the shielding, which provided the important evidence to reduce tank wall eddy current loss effectively. The calculating methods have been proved to be accuracy after experiment.

Математическое описание и анализ сигнала виброиндукционного преобразователя при воздействии нормальной составляющей магнитных потоков рассеяния над дефектным участком

2021 ◽  
Vol 7 ◽  
pp. 19-27
Author(s):  
Ю.Л. Николаев ◽  
П.Н. Шкатов ◽  
Э.Ф. Ахметшина ◽  
А.А. Саморуков
Keyword(s):  
Magnetic Field ◽  
Mathematical Model ◽  
Initial Data ◽  
Vibration Frequency ◽  
Magnetic Field Intensity ◽  
Theoretical Research ◽  
Leakage Magnetic Field ◽  
Induction Transducer ◽  
Experimental Researches ◽  
Defective Area

Theoretical and experimental researches of vibration-induction transducer (VIT) outlet signal formed during exposure to normal leakage magnetic field intensity component Hn over the defective area were carried out. Theoretical research is based on an assumption that VIT signal is a trigonometric series that is limited by first five harmonics. As initial data for mathematical model creation, well-known conformities for Hn distribution over the defective area were used. Based on acquired mathematical model conformities of VIT signal harmonical composition permutation during its movement over the defective area with varying amplitudes and vibration frequency were found. Theoretical research results were proven experimentally. Moreover, additional possibilities of this way of magnetic testing are shown in comparison with conventional ones.

A Study on the Magnetic Distribution of Nd-Fe-B Permanent Magnets in Pipeline in Line Inspection Tool

2018 ◽  
Author(s):  
Pan Song ◽  
Xiaoying Tang ◽  
ShaoJun Wang ◽  
Bin Ren ◽  
Yantian Zuo ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Permanent Magnets ◽  
Oil And Gas ◽  
Field Performance ◽  
Magnetic Intensity ◽  
Leakage Magnetic Field ◽  
Element Simulation ◽  
Pressure Pipeline ◽  
Nondestructive Testing Method

The pressure pipeline in line inspection technology is the most effective nondestructive testing method to detect the quality of buried oil and gas pipelines at present. In line inspection tool usually uses magnetic flux leakage (MFL) technology to detect the change of leakage magnetic field to detect pipeline defects. Permanent magnets magnetize the wall of the pipeline as an excitation. During the detection process, the magnetic field performance of permanent magnets is required to be high. At the same time, the magnetic performance of the permanent magnet in the magnetic cleaning pipe also determine the cleaning effect inside the pipeline. In this paper, the magnetic distribution of permanent magnets is studied and the Nd-Fe-B permanent magnets with the best magnetic properties are taken as the objects. The finite element simulation is used to optimize the shape of the permanent magnets with better magnetic distribution, and the magnetic intensity factors of the preferred cylindrical permanent magnets are analyzed. In addition, three experiments of the influence of temperature, the influence of the ferromagnetic combination, and the influence of the environment medium are conducted. As a result, the relationship between the magnetic intensity of the Nd-Fe-B permanent magnets and the factors is obtained. The conclusion is of great significance to the design and research of permanent magnetic circuit in line inspection magnetization device.

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