The long-term stability of an atomic magnetic resonance standard system for the reproduction of direct current and magnetic flux density

2003 ◽  
Vol 52 (2) ◽  
pp. 433-435
Author(s):  
V.Ya. Shifrin ◽  
V.N. Khorev ◽  
A.Ye. Shilov ◽  
Po Gyu Park
Keyword(s):  
Magnetic Resonance ◽  
Magnetic Flux ◽  
Flux Density ◽  
Direct Current ◽  
Standard System ◽  
Magnetic Flux Density ◽  
Term Stability ◽  
Long Term Stability ◽  
Atomic Magnetic Resonance

scholarly journals Design Analysis of a Dual Rotor Permanent Magnet Machine driven Electric Vehicle

2018 ◽  
Vol 152 ◽  
pp. 03004
Author(s):  
Mohd Izzat Bin Zainuddin ◽  
CV Aravind
Keyword(s):  
Magnetic Flux ◽  
Permanent Magnet ◽  
Flux Density ◽  
Direct Current ◽  
Load Condition ◽  
Magnetic Flux Density ◽  
Torque Density ◽  
Proposed Model ◽  
Outer Rotor ◽  
Electric Bike

Electric bike in urban countries such as Europe and China commonly used the brushless direct current machine (BLDC) as it able to produce high torque to transport the user from one place to another. However, BLDC torque density can’t be improving due to limitation magnetic flux generated by the permanent magnet. Therefore, the performance of electric bike can’t be improved. Outer rotor BLDC machine design able to improve the torque density of the motor due to increase radius of the motor which can be explained by simple physics equation (Torque = Force x radius). However, an outer rotor machine only generates constant speed, which is not suitable for operating under tractive load condition, especially electric bike. The proposed model is a new novel of double layer outer rotor BLDCPM machine which able to amplify the magnetic flux density and improve the torque density of the machine. The mutual magnetic coupling between the inner and outer rotor of the proposed model increase the magnetic flux intensity as both of them acts as individual parts. Thus, the magnetic flux generated by both rotors are double which resulted in improving the performance of the E-bike. Designing parameters and analysing the performance of the proposed 2D model is done using FEA tools. Evaluation of the conventional and proposed model by comparing torque performance, magnetic flux density and motor constant square density. Other than that, speed torque graph also is evaluated to justify either it can operate similarly to ICE engine with gears. Two model is designed which is Single Outer Rotor Brushless Direct Current (SORBLDC) and Double Outer Rotor Brushless Direct Current (DORBLDC) operated with the same cases of 27 Amp current supplied to it and operate under various speed from 500 rpm to 2000 rpm. The average torque produce by the conventional and proposed model are 2.045439 Nm and 3.102648 Nm. Furthermore, improvement of the proposed model to conventional model in terms of motor constant square density by 24.92%. Therefore, the proposed model able to improve the magnetic flux by amplifying which resulted to increase the torque density of the machine. Furthermore, the speed-torque graph of the proposed machine shows similarity with speed torque graph of ICE engine. Thus, the proposed machine is suitable to operate for bike application

scholarly journals Timing noise and the long-term stability of pulsar profiles

2012 ◽  
Vol 8 (S291) ◽  
pp. 183-188
Author(s):  
Andrew Lyne
Keyword(s):  
Flux Density ◽  
Close Correlation ◽  
Pulse Emission ◽  
Emission Properties ◽  
Term Stability ◽  
Long Term Stability ◽  
Observational Status ◽  
Timing Noise ◽  
Current Flows

AbstractIt has recently been shown that there is a close correlation between the slowdown rates and the pulse shapes of six pulsars, and between the slowdown rates and the flux density of three others. This indicates that these phenomena are related by changes in the current flows in the pulsar magnetospheres. In this paper we review the observational status of these studies, which have now been extended to a total of 16 pulsars having correlated slowdown and pulse emission properties. The changes seem to be due to sudden switching between just two discrete magnetospheric states in the well-known processes of mode-changing and pulse nulling. We also address how widespread these phenomena are in the wider pulsar population.

scholarly journals Current Density Imaging Using Directly Measured HarmonicBzData in MREIT

2013 ◽  
Vol 2013 ◽  
pp. 1-9 ◽  
Author(s):  
Chunjae Park ◽  
Oh In Kwon
Keyword(s):  
Magnetic Resonance ◽  
Magnetic Flux ◽  
Flux Density ◽  
Current Density ◽  
Background Field ◽  
Magnetic Flux Density ◽  
Reconstruction Procedure ◽  
Phantom Experiment ◽  
Impedance Tomography ◽  
Space Data

Magnetic resonance electrical impedance tomography (MREIT) measures magnetic flux density signals through the use of a magnetic resonance imaging (MRI) in order to visualize the internal conductivity and/or current density. Understanding the reconstruction procedure for the internal current density, we directly measure the second derivative ofBzdata from the measuredk-space data, from which we can avoid a tedious phase unwrapping to obtain the phase signal ofBz. We determine optimal weighting factors to combine the derivatives of magnetic flux density data,∇2Bz, measured using the multi-echo train. The proposed method reconstructs the internal current density using the relationships between the induced internal current and the measured∇2Bzdata. Results from a phantom experiment demonstrate that the proposed method reduces the scanning time and provides the internal current density, while suppressing the background field inhomogeneity. To implement the real experiment, we use a phantom with a saline solution including a balloon, which excludes other artifacts by any concentration gradient in the phantom.

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