scholarly journals The irony of the magnet system for Kibble balances - a review

Metrologia ◽  
2021 ◽  
Author(s):  
Shisong Li ◽  
Stephan Schlamminger
Keyword(s):  
Magnetic Flux ◽  
Magnetic Circuit ◽  
Geometric Factor ◽  
Magnet System ◽  
Essential Component ◽  
Design Considerations ◽  
Systematic Uncertainties ◽  
Velocity Mode

Abstract The magnet system is an essential component of the Kibble balance, a device that is used to realize the unit of mass. It is the source of the magnetic flux, and its importance is captured in the geometric factor $Bl$. Ironically, the $Bl$ factor cancels out and does not appear in the final Kibble equation. Nevertheless, care must be taken to design and build the magnet system because the cancellation is perfect only if the $Bl$ is the same in both modes: the weighing and velocity mode. This review provides the knowledge necessary to build a magnetic circuit for the Kibble balance. In addition, this article discusses the design considerations, parameter optimizations, practical adjustments to the finished product, and an assessment of systematic uncertainties associated with the magnet system.

Effects of contact gap on nondestructive evaluation using magnetic measurement for ferromagnetic steel

2020 ◽  
Vol 64 (1-4) ◽  
pp. 969-975
Author(s):  
Hiroaki Kikuchi ◽  
Yuki Sato
Keyword(s):  
Magnetic Flux ◽  
Nondestructive Evaluation ◽  
Effective Permeability ◽  
Magnetic Circuit ◽  
Magnetic Measurement ◽  
Air Gap ◽  
Motive Force ◽  
Hysteresis Curve ◽  
Evaluation Technique ◽  
Ferromagnetic Steel

We investigated effects of contact gap on magnetic nondestructive evaluation technique using a magnetic single-yoke probe. Firstly, we evaluated hysteresis curves and impedance related to permeability of the material measured by a single-yoke probe, when an air gap length between the probe and specimens changes. The hysteresis curve gradually inclines to the axis of the magneto-motive force and magneto-motive force at which the magnetic flux is 0 decreases with increasing the gap length. The effective permeability also decreases with increasing the gap thickness. The incremental of gap thickness increases the reluctance inside the magnetic circuit composed of the yoke, specimen and gap, which results in the reduction of flux applying to specimen.

Analysis of structure factors affecting suspension force of permanent magnet system with variable magnetic flux path control

2020 ◽  
Vol 64 (1-4) ◽  
pp. 1495-1504
Author(s):  
Fangchao Xu ◽  
Yongquan Guo ◽  
Ran Zhou ◽  
Junjie Jin ◽  
Chuan Zhao ◽  
...  
Keyword(s):  
Magnetic Flux ◽  
Permanent Magnet ◽  
System Structure ◽  
Magnet System ◽  
Load Torque ◽  
Factors Affecting ◽  
Annular Gap ◽  
Path Control ◽  
Structure Factors ◽  
Flux Path

To solve the problem of reduction of suspension force of permanent magnet system with variable magnetic flux path control, according to the structure of the system, suspension principle of the permanent magnet system with variable magnetic flux path control and the generation principle of the load torque, the influence of the mechanical structure of the system on the suspension force is analyzed by changing part of parameters of the system structure. The results show that the existence of magnetic isolation plate is the main reason for the decrease of suspension force, the permanent magnet ring can be thickened to 11.91 mm, the annular gap can be reduced to 1 mm, thickness of the “F” shaped magnetizer can be increased to 9 mm to increase the suspension force.

Effects of Detector Dynamics on Magnetic Flux Leakage Signals From Dents and Gouges

2012 ◽  
Author(s):  
Lynann Clapham ◽  
Vijay Babbar
Keyword(s):  
Magnetic Flux ◽  
Pipe Wall ◽  
Magnetic Flux Leakage ◽  
Signal Loss ◽  
Magnet System ◽  
High Speeds ◽  
Study Results ◽  
Dynamic Case ◽  
Corrosion Defects ◽  
Flux Leakage

The current study was designed to model the dynamic effects of detector ride and magnet liftoff on Magnetic Flux Leakage (MFL) signals from dents as well as gouges that have significant denting. The MFL tools have long been used for the detection and sizing of corrosion defects. This is comparatively straightforward for a number of reasons, one of which is that the MFL detector assembly can ride relatively smoothly along the inner pipe wall surface. This is not the case when significant denting is present, since the dent presents a perturbation in the pipe wall that can cause liftoff of the detector or magnet system. Since the tool travels at relatively high speeds down the pipe, the dent itself can cause the detector to lose contact with the trailing half of the dent. In addition, the magnet pole piece may experience partial liftoff as it traverses the dent, thus causing a change in the local flux density. In this study results from ‘static’ measurements are compared with a dynamic case in which detector liftoff is simulated through modeling and experiment. Results are discussed regarding the severity of MFL signal loss at the trailing edge of the defect as a result of detector liftoff. The effect of partial liftoff of the magnet as it passes over the dent is also examined. Magnet liftoff is found to increase the local magnetic flux near the liftoff region, causing the MFL signal from the dent wall to increase rather than decrease in the vicinity of magnet liftoff region.

A Miniature Energy Harvesting Device Using Martensite Variant Reorientation

2013 ◽  
Vol 738-739 ◽  
pp. 411-415 ◽  
Author(s):  
Manfred Kohl ◽  
Rui Zhi Yin ◽  
Viktor Pinneker ◽  
Yossi Ezer ◽  
Alexei Sozinov
Keyword(s):  
Magnetic Field ◽  
Energy Harvesting ◽  
Magnetic Flux ◽  
Output Voltage ◽  
Permanent Magnets ◽  
Magnetic Circuit ◽  
Compressive Loading ◽  
Piezoelectric Bimorph ◽  
Martensite Variant ◽  
Cyclic Motion

This paper presents a miniature energy harvesting device that makes use of stress-induced cyclic martensite variant reorientation in a Ni-Mn-Ga single crystal of 0.3x2x2 mm³ size. The stress- and magnetic field-induced reorientation is investigated for single crystalline Ni50.2Mn28.4Ga21.4 specimens of 0.3 mm thickness that are cut along the (100) direction and subjected to uniaxial compressive loading. A demonstrator is presented consisting of a FSMA specimen placed in the gap of a magnetic circuit to guide and enhance the field of biasing permanent magnets. The cyclic motion of a piezoelectric bimorph actuator is used to mechanically load the FSMA specimen. The corresponding change of magnetic flux induces an electrical voltage in a pick-up coil (N=2000 turns). The effects of biasing magnetic field, strain amplitude and strain velocity are investigated. An optimum magnetic field of 0.4 T exists, where the output voltage reaches 120 mV at a strain velocity of 0.006 ms-1.

A Mathematical Model of a Modified Voice Coil Energy Harvester

2011 ◽  
Author(s):  
Alireza Hekmati ◽  
Siamak Arzanpour
Keyword(s):  
Magnetic Field ◽  
Magnetic Flux ◽  
Flux Density ◽  
Peak Power ◽  
Magnetic Field Intensity ◽  
Magnetic Circuit ◽  
Magnetic Flux Density ◽  
Magnetic Conductor ◽  
Magnetic Circuits ◽  
The Magnetic Field

This paper presents a mathematical modeling of a modified voice coil generator, which consists of a moving coil within a fixed magnetic circuit. The simulation has been done with Comsol Multiphysics software, which is a powerful tool to demonstrate the pattern of magnetic field and calculate the induced current in the coil. In our simulations, the magnetic circuit consists of the magnetic conductor and the air gap. In this analysis, the magnetic flux density and the magnetic field intensity are calculated. Moreover, through calculation of the total reluctance of the magnetic circuit and employing the ohm’s law for magnetic circuits, the effect of the length and cross section of the total circuit on the magnetic flux are investigated. Finally, a pattern for the magnetic flux density are demonstrated and the simulation result indicates that the magnetic field is well concentrated on the coil area, therefore this prototype can capture and convert most of the kinetic energy to electricity. A prototype has been fabricated and tested on the shaker. The experimental results indicate that this setup is able to produce the maximum voltage of 0.326 V and the peak power equal to 2.605 mW in 35 Hz frequency and 1 mm peak to peak amplitude.

Current-Fed Flyback Push-Pull DC-DC Converter Based on Three-Phase Transformer

2014 ◽  
Vol 614 ◽  
pp. 164-167
Author(s):  
You Chen Yuan ◽  
Yang Zhang ◽  
Yu Wei Chen
Keyword(s):  
Magnetic Flux ◽  
High Frequency ◽  
Magnetic Circuit ◽  
Magnetic Loop ◽  
Test Results ◽  
Static And Dynamic Characteristics ◽  
Three Phase ◽  
Independent Functions ◽  
Flow Through ◽  
Efficiency And Reliability

Three-phase current-fed flyback push-pull dc-dc converter is proposed in this paper, which is a new circuit topology putting into practice based on current-fed flyback push-pull dc-dc converter. Structure is simplified; cost is cut down; efficiency and reliability are improved all by the high frequency three-phase transformer technique that carries out functions of flyback transformer as well as push-pull transformer at the same time. Three-phase transformer can be separated into relatively independent functions of flyback transformer and push-pull transformer with the reluctance produced by the magnetic gap in the central phase; the flyback transformer produces only common-mode flux in the magnetic circuit of push-pull transformer and does not influence its output signal; the magnetic flux in push-pull transformer is blocked by the magnetic gap and can only flow through the outer magnetic loop. Investigational device is designed; static and dynamic characteristics are observed and test results are verified by the experimentation.

scholarly journals The magnetic circuit analysis of the transverse magnetic flux generator in no-load mode

2020 ◽  
Vol 0 (3 (1357)) ◽  
pp. 101-105
Author(s):  
Андрій Володимирович Єгоров ◽  
Андрій Михайлович Маслєнніков ◽  
Олексій Олександрович Дунєв ◽  
Руслан Вячеславович Бредун
Keyword(s):  
Magnetic Flux ◽  
Magnetic Circuit ◽  
Transverse Magnetic ◽  
Circuit Analysis ◽  
Load Mode

scholarly journals Preliminary experimental evaluation of a novel loudspeaker featuring magnetorheological fluid surround absorber

2020 ◽  
Vol 17 (2) ◽  
pp. 922 ◽  
Author(s):  
Endra Dwi Purnomo ◽  
Ubaidillah Ubaidillah ◽  
Fitrian Imaduddin ◽  
Iwan Yahya ◽  
Saiful Amri Mazlan
Keyword(s):  
Magnetic Flux ◽  
Yield Stress ◽  
Experimental Evaluation ◽  
Flux Distribution ◽  
Magnetic Circuit ◽  
Experimental Result ◽  
The Finite Element Method ◽  
Shear Yield Stress ◽  
Shear Yield ◽  
Novel Design

<span>A novel design of magnetorheological fluids (MRF) based surround device in a loudspeaker system was studied in this article. The main objective of this research is to design a new surround device of the loudspeaker that can be easily controlled its damping. Therefore, it was predicted that the audio pressure level on the loudspeaker could be easily manipulated at a different sound source by applying a certain magnetic field. This function could not be reached using one conventional speaker system. Firstly, a set of an electromagnetic device containing MRF was designed to replace the conventional rubber surround. The magnetic circuit was then evaluated using the finite element method magnetics to study the flux distribution in the MRF area. The current was varied from 0.25 to 0.75 A by an interval of 0.25 A. The magnetic flux resulted from the simulation was then logged and used as the based value for predicting the change of shear yield stress. The base properties of the shear yield stress of the MRF against the magnetic flux was obtained from previous experimental result. Therefore, it was hopefully the prediction could be closed to the real system. Based on the simulation result, the shear yield stress varied from 43 to 49 Mpa or about 15 % increment. </span><span lang="IN">A simple experimental work was carried out. By applying particular direct current into the coil, the sound quality generated by the loudspeaker shows different values</span><span>.</span><span lang="IN"> Based on the preliminary experiment, the level of decibel decreased about 3 dB as the application of magnetic fields. The idea has been proven in this preliminary experimental evaluation.</span>

scholarly journals Design of the magnet system of the neutron decay facility PERC

2019 ◽  
Vol 219 ◽  
pp. 04007 ◽  
Author(s):  
Xiangzun Wang ◽  
Carmen Ziener ◽  
Hartmut Abele ◽  
Stefan Bodmaier ◽  
Dirk Dubbers ◽  
...  
Keyword(s):  
Superconducting Magnet ◽  
New Physics ◽  
Neutron Decay ◽  
Central Component ◽  
Uniform Field ◽  
Magnet System ◽  
Systematic Uncertainties ◽  
Superconducting Magnet System ◽  
Under Construction

The PERC (Proton and Electron Radiation Channel) facility is currently under construction at the research reactor FRM II, Garching. It will serve as an intense and clean source of electrons and protons from neutron beta decay for precision studies. It aims to contribute to the determination of the Cabibbo-Kobayashi-Maskawa quark-mixing element Vud from neutron decay data and to search for new physics via new effective couplings. PERC's central component is a 12 m long superconducting magnet system. It hosts an 8 m long decay region in a uniform field. An additional high-field region selects the phase space of electrons and protons which can reach the detectors and largely improves systematic uncertainties. We discuss the design of the magnet system and the resulting properties of the magnetic field.

Sign in / Sign up

Export Citation Format

Share Document