scholarly journals Gauge-invariant perturbation expansion in powers of electric charge for the density-of-states of a network model for charged-particle motion in a uniform background magnetic flux density

2021 ◽  
Vol 62 (7) ◽  
pp. 071901
Author(s):  
F. D. M. Haldane
Keyword(s):  
Charged Particle ◽  
Magnetic Flux ◽  
Flux Density ◽  
Density Of States ◽  
Network Model ◽  
Particle Motion ◽  
Perturbation Expansion ◽  
Magnetic Flux Density ◽  
Gauge Invariant ◽  
Uniform Background

scholarly journals Design of a New 1D Halbach Magnet Array with Good Sinusoidal Magnetic Field by Analyzing the Curved Surface

Sensors ◽  
2021 ◽  
Vol 21 (7) ◽  
pp. 2522
Author(s):  
Guangdou Liu ◽  
Shiqin Hou ◽  
Xingping Xu ◽  
Wensheng Xiao
Keyword(s):  
Magnetic Field ◽  
Magnetic Flux ◽  
Permanent Magnet ◽  
Flux Density ◽  
Permanent Magnets ◽  
Air Gap ◽  
Curved Surface ◽  
Magnetic Flux Density ◽  
Sinusoidal Magnetic Field ◽  
The Magnetic Field

In the linear and planar motors, the 1D Halbach magnet array is extensively used. The sinusoidal property of the magnetic field deteriorates by analyzing the magnetic field at a small air gap. Therefore, a new 1D Halbach magnet array is proposed, in which the permanent magnet with a curved surface is applied. Based on the superposition of principle and Fourier series, the magnetic flux density distribution is derived. The optimized curved surface is obtained and fitted by a polynomial. The sinusoidal magnetic field is verified by comparing it with the magnetic flux density of the finite element model. Through the analysis of different dimensions of the permanent magnet array, the optimization result has good applicability. The force ripple can be significantly reduced by the new magnet array. The effect on the mass and air gap is investigated compared with a conventional magnet array with rectangular permanent magnets. In conclusion, the new magnet array design has the scalability to be extended to various sizes of motor and is especially suitable for small air gap applications.

scholarly journals Coil Positioning for Wireless Power Transfer System of Automatic Guided Vehicle Based on Magnetic Sensing

Sensors ◽  
2020 ◽  
Vol 20 (18) ◽  
pp. 5304
Author(s):  
Ce Liang ◽  
Yanchi Zhang ◽  
Zhonggang Li ◽  
Feng Yuan ◽  
Guang Yang ◽  
...  
Keyword(s):  
Magnetic Flux ◽  
Data Fusion ◽  
Flux Density ◽  
Sensor Array ◽  
Wireless Power Transfer ◽  
Magnetic Flux Density ◽  
Power Transfer ◽  
Wireless Power ◽  
Automatic Guided Vehicle ◽  
Receiving Coil

As an auxiliary function of the wireless power transfer (WPT) system, coil positioning can solve the power and efficiency degradation during power transmission caused by misalignment of the magnetic coupler. In this paper, a Hall sensor array is used to measure the change of magnetic flux density. By comparing the multisensor data fusion results with the preset data obtained from the coil alignment, the real-time accurate positioning of the receiving coil can be realized. Firstly, the positioning model of the receiving coil is built and the variation of magnetic flux density with the coil misalignment is analyzed. Secondly, the arrangement of the Planar 8-direction symmetric sensor array and the positioning algorithm based on data fusion of magnetic flux density variations are proposed. In order to avoid coil positioning misalignment caused by the unstable magnetic field distribution which is actually affected by the change of mutual inductance during automatic guided vehicle (AGV) alignment, the constant current strategy of primary and secondary sides is proposed. Finally, the coil positioning experimental platform is built. The experimental results show that the coil positioning method proposed in this paper has high accuracy, and the positioning error is within 4 cm.

scholarly journals Assessment of magnetic flux density properties of electromagnetic noninvasive phrenic nerve stimulations for environmental safety in an ICU environment

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
K. Friedrich Kuhn ◽  
Julius J. Grunow ◽  
Pascal Leimer ◽  
Marco Lorenz ◽  
David Berger ◽  
...  
Keyword(s):  
Intensive Care Unit ◽  
Intensive Care ◽  
Magnetic Flux ◽  
Flux Density ◽  
Muscle Fiber ◽  
Phrenic Nerve ◽  
Magnetic Flux Density ◽  
Training Center ◽  
Electromagnetic Stimulation ◽  
Stimulation Of

AbstractDiaphragm weakness affects up to 60% of ventilated patients leading to muscle atrophy, reduction of muscle fiber force via muscle fiber injuries and prolonged weaning from mechanical ventilation. Electromagnetic stimulation of the phrenic nerve can induce contractions of the diaphragm and potentially prevent and treat loss of muscular function. Recommended safety distance of electromagnetic coils is 1 m. The aim of this study was to investigate the magnetic flux density in a typical intensive care unit (ICU) setting. Simulation of magnetic flux density generated by a butterfly coil was performed in a Berlin ICU training center with testing of potential disturbance and heating of medical equipment. Approximate safety distances to surrounding medical ICU equipment were additionally measured in an ICU training center in Bern. Magnetic flux density declined exponentially with advancing distance from the stimulation coil. Above a coil distance of 300 mm with stimulation of 100% power the signal could not be distinguished from the surrounding magnetic background noise. Electromagnetic stimulation of the phrenic nerve for diaphragm contraction in an intensive care unit setting seems to be safe and feasible from a technical point of view with a distance above 300 mm to ICU equipment from the stimulation coil.

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