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Optimization on magnetic properties of Nd-doped Fe_(3)O_(4) nanoparticles for magnetic shielding fabrics

Journal of Rare Earths 2024年第4期42卷 683-689页

作者： Xiaolei Song Congzhu Xu Yuyan Wang Huizhen Ke Yonggui Li Qufu Wei Xinqun Feng Faculty of Clothing and Design Minjiang UniversityFuzhou350108China Fujian Key Laboratory of Novel Functional Textile Fibers and Materials Minjiang UniversityFuzhou350108China College of Textile and Clothing Jiangnan UniversityWuxi214122China College of Fashion and Design Donghua UniversityShanghai201620China

High magnetic protective fabrics with rare earth Nd doped Fe_(3)O_(4) nanoparticles were fabricated via a grafting *** structure,crystal form,and elemental composition of nanoparticles were investigated by transmission electron microscopy,energy dispersive X-ray,X-ray powder diffraction,and X-ray photoelectron *** obtained NdFe_(2)O_(4) nanoparticles show spherical shape with fine dispersion and reasonable element ***,they demonstrate fine superparamagnetic properties with a magnetic saturation value of 29.25 A·m^(2)/g and low coercivity of 1.902 mT through the vibrating sample magnetometry technique,which can be well developed in magnetic shielding protective ***,the cotton fabrics with plain weave were finished by a proofing rapier loom as a *** NdFe_(2)O_(4) nanoparticles underwent some appropriate surface modification and then were grafted onto the cotton fabrics by a bridge agent of N,N’-dissuccinimidyl *** morphology,structure,dispersion effect,and electromagnetic protective properties of the fabrics were observed through scanning electron microscopy,Fourier infrared spectroscopy,thermogravimetric analysisdifferential scanning calorimetry(TG-DSC),and a vector network *** reliable fabrics with grafting reaction on the interface are expected to have potential applications in the field of electromagnetic protection and biomedicine fields.

关键词： magnetic property Nd Fe_(3)O_(4)nanoparticles magnetic shielding Fabrics Rare earths

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magnetic shielding property for cylinder with circular, square, and equilateral triangle holes

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Chinese Physics B 2021年第6期30卷 255-260页

作者：郝思源娄小平祝静陈广伟李慧宇 Key Laboratory of the Ministry of Education for Optoelectronic Measurement Technology and Instrument Beijing 100192China Beijing Laboratory of Optical Fiber Sensing and System Beijing Information Science&Technology UniversityBeijing 100016China Beijing Key Laboratory of Optoelectronic Measurement Technology Beijing Information Science&Technology UniversityBeijing 100192China

The shielding property of cylinder with circular, square, and equilateral triangle holes was investigated by finite element analysis(FEA). The hole area(S_(hole)) plays an important role in magnetic circuit on the surface of cylinder. When Sholeis less than the critical area(S_(H)), cylinder with three shapes of holes obtained the same remanent magnetization inside,indicating that the shielding property is unaffected by the shape of the hole. Hence, high-permeability material is the major path of the magnetic field. On the condition of S_(hole)> S_(H), the sequence of the shielding property is equilateral triangle >square > circular, resulting from magnetoresistance of leakage flux in air dielectric. Besides, the anisotropy of shielding property caused by hole structural differences of the cylinder is evaluated. We find that a good shielding effectiveness is gained in the radial direction, compared with the axis direction. This research focuses on providing a theoretical support for the design of magnetic shield and improvement on the magnetic shielding ability.

关键词： SERF atomic magnetometer magnetic shielding holes finite element analysis(FEA)

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Study on magnetic shielding for Performance Improvement of Axial-Field Dual-Rotor Segmented Switched Reluctance Machine

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CES Transactions on Electrical Machines and Systems 2021年第1期5卷 50-61页

作者： Wei Sun Qiang Li Le Sun Xuefeng Jiang School of Automation Nanjing University of Science and TechnologyNanjing 210094China

A category of permanent-magnet-shield(PM-shield)axial-field dual-rotor segmented switched reluctance machines(ADS-SRMs)are presented in this *** topologies are featured by using the magnetic material to shield the flux leakage in the stator and rotor ***,the deployed magnets weaken the magnetic saturation in the iron core,thus increasing the main ***,the torque-production capability can be increased *** the PM-shield topologies are proposed and designed based on the magnetic equivalent circuit(MEC)model of ADS-SRM,which is the original design deploying no *** features of all the PM-shield topologies are compared with the original design in terms of the magnetic field distributions,flux linkages,phase inductances,torque components,and followed by their motion-coupled analyses on the torque-production capabilities,copper losses,and *** the cost reduction and the stable ferrite-magnet supply,an alternative proposal using the ferrite magnets is applied to the magnetic *** magnet demagnetization analysis incorporated with the thermal behavior is performed for further verification of the motor performance.

关键词： Switched reluctance machine(SRM) magnetic shielding magnetic equivalent circuit(MEC) demagnetization thermal behavior.

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Double-ring high-frequency common-mode switching oscillation current sensor for inverter-fed machine winding insulation monitoring

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Global Energy Interconnection 2024年第1期7卷 106-116页

作者： Lingqing Pan Xizhou Du Xing Lei Ting Ye Dawei Xiang Hao Li College of Electrical Power Engineering Shanghai University of Electric PowerShanghai 200090P.R.China State Grid Shanghai Municipal Electric Power Company Shanghai 200122P.R.China College of Electronics and Information Engineering Tongji UniversityShanghai 201804P.R.China

Insulation failure significantly contributes to the unpredictable shutdown of power *** to the partial discharge and high-frequency(HF)injection methods,the HF common-mode(CM)leakage current method offers a non-intrusive and highly sensitive ***,the detection of HF CM currents is susceptible to interference from differential-mode(DM)currents,which exhibit high-amplitude and multifrequency components during normal *** address this challenge,this paper proposes a double-ring current sensor based on the principle of magnetic shielding for inverter-fed machine winding insulation *** inner ring harnesses the magnetic aggregation effect to isolate the DM current magnetic field,whereas the outer ring serves as the magnetic core of the Rogowski current sensor,enabling HF CM current ***,the magnetic field distributions of the CM and DM currents were ***,a correlation between the sensor parameters and signal-to-noise ratio of the target HF CM current was ***,an experimental study was conducted on a 3-kW PMSM for *** results indicate that the proposed double-ring HF CM sensor can effectively mitigate DM current *** to a single-ring sensor,a reduction of approximately 40%in the DM component was achieved,which significantly enhanced the precision of online insulation monitoring.

关键词： magnetic shielding Double-ring Common-mode current Maxwell simulation

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Gradient coil design with enhanced shielding constraint for a cryogen-free superconducting MRI system

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magnetic Resonance Letters 2024年第1期4卷 1-9页

作者： Yaohui Wang Weimin Wang Hui Liu Shunzhong Chen Feng Liu Qiuliang Wang Institute of Electrical Engineering Chinese Academy of SciencesBeijing100190China School of Electronic Electrical and Communication EngineeringUniversity of Chinese Academy of SciencesBeijing100049China School of Electronics&Institute of Biomedical Engineering Peking University&Shenzhen Graduate SchoolShenzhen518055China School of Information Technology and Electrical Engineering The University of QueenslandSt LuciaBrisbaneQLD4072Australia

The relatively fragile low-temperature stability of cryogen-free superconducting magnetic resonance imaging(MRI)magnets requires the careful management of exogenous heat sources.A strongly shielded gradient magnetic field is important for the optimal operation of cryogen-free MRI *** this study,we present an enhanced shielding method incorporating a regionalized stray field constraining *** optimizing the constraint parameters,we could develop engineering-feasible gradient coil schemes without increasing system complexity but with the stray field intensity reduced by *** real measurement in an integrated MRI system,the developed gradient assembly demonstrated good performance and supported to output images of excellent *** findings suggested that the proposed method could potentially form a useful design paradigm for cryogen-free MRI magnets.

关键词： MRI Gradient coil Superconducting magnet Cryogen-free magnetic shielding

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shielding EFFECTIVENESS OF MULTILAYERED SHIELDS FOR magnetic FIELD NONSINUSOIDAL SOURCES

SHIELDING EFFECTIVENESS OF MULTILAYERED SHIELDS FOR MAGNETIC...

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2002 3rd International Symposium on Electromagnetic Compatibility

作者： A.Massarini U.Reggiani L.Sandrolini Dipartimento di Ingegneria dell'Informazione Universita di Modena e Reggio EmiliaModenaItaly Dipartimento di Ingegneria Elettrica Universita di BolognaBolognaItaly

＜正＞The magnetic field generated by a nonsinusoidal periodic source is shielded by a planar infinite multilayered shield composed of high permeability and high conductivity *** means of a transform analytical approa... 详细信息

关键词： magnetic shielding Frequency Fourier series magnetic materials Modems magnetic analysis magnetic flux Magnetostatic waves Permeability Conductivity

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Evaluation of second-order Zeeman frequency shift in NTSC-F2

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Chinese Physics B 2021年第7期30卷 163-170页

作者：施俊如王心亮白杨杨帆管勇刘丹丹阮军张首刚 National Time Service Center Chinese Academy of SciencesXi'an 710600China Key Laboratory of Time and Frequency Primary Standards Chinese Academy of SciencesXi'an 710600China University of Chinese Academy of Sciences Beijing 100049China

Caesium atomic fountain clock is a primary frequency standard,which realizes the duration of *** performance is mostly dominated by the frequency accuracy,and the C-field induced second-order Zeeman frequency shift is the major effect,which limits the accuracy *** applying a high-precision current supply and high-performance magnetic shieldings,the C-field stability has been improved *** order to achieve a uniform C-field,this paper proposes a doubly wound C-field solenoid,which compensates the radial magnetic field along the atomic flight region generated by the lead-out single wire and improves the accuracy evaluation of second-order Zeeman frequency *** on the stable and uniform C-field,we launch the selected atoms to different heights and record the magnetically sensitive Ramsey transition|F=3,mF=-1→|F=4,mF=-1 central frequency,obtaining this frequency shift as 131.03×10^(-15)and constructing the C-field profile(σ=0.15 n T).Meanwhile,during normal operation,we lock NTSC-F2 to the central frequency of the magnetically sensitive Ramsey transition|F=3,mF=-1→|F=4,mF=-1 fringe for ten consecutive days and record this frequency fluctuation in time *** first evaluation of second-order Zeeman frequency shift uncertainty is 0.10×10^(-15).The total deviation of the frequency fluctuation on the clock transition induced by the C-field instability is less than 2.6×10^(-17).Compared with NTSC-F1,NTSC-F2,there appears a significant improvement.

关键词： caesium atomic fountain clock second-order Zeeman frequency shift C-field magnetic shielding

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Transmission Efficiency of Different shielding Structures in Wireless Power Transfer Systems for Electric Vehicles

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CSEE Journal of Power and Energy Systems 2021年第6期7卷 1247-1255页

作者： Jianchao Li Fanghui Yin Liming Wang Shenzhen Environmental Science and New Energy Technology Engineering Laboratory Tsinghua-Berkeley Shenzhen InstituteTsinghua UniversityShenzhen 518055China the Graduate School at Shenzhen Tsinghua UniversityShenzhen 518055China

Wireless Power Transfer(WPT)charging systems can cause eddy loss on the steel part and the chassis of an Electric Vehicle(EV).To study different shielding structures’influence on the transmission efficiency of a WPT system,boundary conditions and assumptions of the WPT model in a quasistationary electromagnetic field were established and a finite element method(FEM)was *** shielding effectiveness of ferrite plate and annular aluminum plate were investigated as well as their effects on the coupling coefficient of *** was found that,the setting of ferrite core enhanced the transmission field strength,improved the coupling between two coils,and increased transmit power as well as the actual eddy *** actual necessary shielding-area was not confined into the samesize area but distributed around the edge of the *** arranging specialized size annular aluminum plates between the chassis and ferrite core,the eddy loss can be effectively shielded and an optimal transmission efficiency can breached with an acceptable coupling coefficient *** optimized ferrite bar structure and its EMC characteristics were also *** was also found that with equal volume,the optimized ferrite bar structure had better performance in EMC and coupling enhancement than the full ferrite plate.

关键词： Coupling co-efficiency eddy loss FEM magnetic shielding WPT

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Design of a superconducting magnet for CADS

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Chinese Physics C 2012年第9期36卷 886-890页

作者：杨晓亮马力祯吴巍郑石钧杜俊杰韩少斐关明智何源 Institute of Modern Physics Chinese Academy of Sciences Graduate University of Chinese Academy of Sciences

This paper describes a superconducting magnet system for the China Accelerator Driven System （CADS）. The magnetic field is provided by one main, two bucking and four racetrack coils. The main coil produces a central field of up to 7 T and the effective length is more than 140 mm, the two bucking coils can shield most of the fringe field, and the four racetrack superconducting coils produce the steering magnetic field. Its leakage field in the cavity zone is about 5 × 10^-5 T when the shielding material Niobium and cryogenic permalloy are used as the Meissner shielding and passive shielding respectively. The quench calculations and protection system are also discussed.

关键词： ADS SC solenoid design leakage field magnetic shielding quench calculation

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