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International Conference on Electrical Machines and Systems (ICEMS)

作者： Dawei Li Ronghai Qu State Key Laboratory of Advanced Electromagnetic Engineering and Technology Huazhong University of Science and Technology Wuhan China

Sinusoidal back-EMF waveform of vernier Permanent Magnet (PM) machines is analyzed in this paper. An analytical expression of Electromotive Force (EMF) of electric machines including vernier machines is developed to analyze EMF harmonics, and the effect of vernier PM machine pole ratio, the ratio of number of rotor poles to stator poles, on the EMF waveform. Moreover, this paper represents several Finite Element Analysis (FEA) models to verify the analysis based on the proposed expression, and the effect of tooth width ratio, which is the ratio of tooth width to tooth pitch, on back-EMF of vernier PM machines, and optimal tooth width ratio is obtained and verified by FEA. Finally, this paper makes comparisons between EMF waveform of vernier PM machines and that of traditional PM machines from the point of view of analytical EMF expression.

关键词： Lead Power capacitors Stators IP networks Harmonic analysis

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IDENTIFIYING THREE KINDS OF DIELECTRIC BARRIER DISCHARGES WITH FAST FOURIER TRANSFORM TECHNIQUES

IDENTIFIYING THREE KINDS OF DIELECTRIC BARRIER DISCHARGES WI...

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The ⅪⅩ International Conference on Gas Discharges and Their Applications

作者： YUNFEI WU QIZHENG YE State Key Laboratory of Advanced Electromagnetic Engineering and Technology College of Electrical and Electronic EngineeringHuazhong University of Science and Technology

We propose a method—the Fourier energy spectrum to identify filamentary,periodic and homogeneous dielectric barrier discharges (DBDs) based on fast Fourier transform techniques(FFT) of the discharge *** radial Fourier energy spectrum(RFES) shows only one peak and the angular Fourier energy spectrum(AFES) shows a serious of random peaks in a filamentary *** RFES and AFES show a serious of periodic peaks in a periodic *** addition to a direct current component,there is no peak for the RFES and AFES in a homogeneous *** an increase of the applied voltage,the RFES gradually shifts right and the AFES gradually shifts up in air at atmospheric pressure with a mesh electrode,it means that the spatial period of the discharge image gradually decreases,and the periodic characteristic of the discharge is more *** results indicate that the method is simple and effective to identify the three different kinds of DBDs.

关键词： DBDs FFT the radial Fourier energy spectrum(RFES) the angular Fourier energy spectrum(AFES) identify

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Effect of oxygen content and heat treatment on carbide precipitation behavior in PM Ni-base superalloys

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International Journal of Minerals,Metallurgy and Materials 2012年第9期19卷 827-835页

作者： Heng-san Liu Lin Zhang Xin-bo He Xuan-hui Qu Hong-min Zhu Guo-qing Zhang State Key Laboratory for Advanced Metals and Materials Beijing Key Laboratory for Powder Metallurgy and Particulate Materials University of Science and Tech-nology Beijing Beijing 100083 China School of Metallurgical and Ecological Engineering University of Science and Technology Beijing Beijing 100083 China National Key Lab of High Temperature Structural Materials Beijing Institute of Aeronautical Materials Beijing 100095 China

The influence of oxygen content and heat treatment on the evolution of carbides in a powder metallurgy （PM） Ni-base superalloy was characterized. The results reveal that oxygen content has little influence on the precipitation of carbides inside the particles. However, under the consolidated state, stable Ti oxides on the particle surface act as nuclei for the precipitation of prior particle boundaries （PPB）. Also, oxygen can diffuse internally along grain boundaries under compressive stress, which favors the precipitation of carbides inside the particles. Therefore, a higher amount of carbides will appear with more oxygen content in the case of consolidated alloys. It is also observed that PPB can be disrupted into discontinuous particles at 1200℃, but this carbide network is hard to be eliminated completely. The combined MC-M23C6 morphology approves the nucleation and growth mechanism of carbide evolution.

关键词： powder metallurgy nickel alloys superalloys oxygen heat treatment carbides precipitation

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Experimental Study on Arc Duration under External Transverse Magnetic Fields in a DC 580V Circuit

Experimental Study on Arc Duration under External Transverse...

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The 26th International Conference on Electrical contacts and the 4th International Conference on Reliability of Electrical Products & Electrical Contacts

作者： Liu Yun Li Zhenbiao Wang Ke Wang Ronghua State Key Laboratory of Advanced Electromagnetic Engineering and Technology College of Electrical and Electronic Engineering Huazhong University of science and technology

ISBN: (纸本)9781622763139

Using transverse magnetic field(TMF) is one of the most important ways to improve the electric life and the breaking capacity of DC *** order to better understand the influence of transverse magnetic field on arc duration,a series of experiments were conducted under external transverse magnetic field with 4 relay contacts in a DC 580V/60A *** permanent magnets,the transverse magnetic field is obtained and the magnetic flux density at center magnet can be varied from 80 to 320 *** results show that the making arc duration is independent of magnetic flux density,but the breaking arc duration is decreased monotonically with the increase of the magnetic flux *** addition,the gradient |Δt/ΔB| of the breaking arc duration is decreased with the increase of the magnetic flux density,which means the curve of t-B tends to be flat.

关键词： transverse magnetic field(TMF) arc duration relay contact

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Phase current differential protection for transformers in wye-delta mode

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Telkomnika 2012年第6期10卷 1280-1286页

作者： Wang, Yuxue Yin, Xianggen Zhang, Zhe Li, Zhenxing The State Key Laboratory of Advanced Electromagnetic Engineering and Technology Huazhong University of Science and Technology Wuhan 430074 China

For the current transformers (CTs) on the delta side measure the line current instead of the phase current, line current differential protection is adopted in transformers connected in wye-delta mode currently. However, the symmetry feature of inrush current in line current differential protection may invalidate the inrush current restrained criterion. A calculating method of current through delta windings according the measured current from CT is proposed in this paper. Using this calculated current, phase current differential protection can be realized. Based on the method an adaptive second harmonic restrained scheme for magnetizing inrush current is presented. The scheme not only adaptively adjusts the secondary harmonic ratio of restrained current but also guarantees the fast action when transformers with internal faults are no-load energized. Consequently the performance of transformer differential protection is greatly improved. Simulation results in Matlab/Simulink validate the proposed method. © 2012 Universitas Ahmad Dahlan.

关键词： Transformer protection

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Inactivate adenovirus by using a room temperature plasma needle

Inactivate adenovirus by using a room temperature plasma nee...

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IEEE International Conference on Plasma Science (ICOPS)

作者： Z. Xiong X. Lu State key laboratory of advanced electromagnetic engineering and technology Huazhong University of Science and Technology Wuhan Hubei China

Summary form only given. A very large number of serious human and animal diseases such as AIDS, SARS, common cold, human and avian influenza, chickenpox, and several others are caused by viral infections. The infectious agents of these diseases are virus nanoparticles (virions) that contain DNA/RNA strands encased in a capsid protein coat and in some cases also in an outer lipid envelope. The virions are usually transmitted from the infected cases through airborne dissemination or diffusion during nosocomial transfusion of blood or body liquids. The onset of the viral infection is usually heralded by the entry of the virion's genetic material into the intracellular space followed by the uncontrollable integration with the host DNA and virus replication. Despite decades of research, virion detection, pre-emptive and post-infection anti-viral treatments and immunotherapies remain ineffective and the morbidity and mortality rates due to the associated infections remain high.

关键词： Plasmas Humans Adenoviruses Needles Diseases DNA Proteins

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Atmospheric plasma brush driven by sub-microsecond voltage pulses

Atmospheric plasma brush driven by sub-microsecond voltage p...

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IEEE International Conference on Plasma Science (ICOPS)

作者： S. Wu X. Lu State key laboratory of advanced electromagnetic engineering and technology Huazhong University of Science and Technology Wuhan Hubei China

Plasma jet devices generate plasmas in an open space (surrounding air) rather than in lieu of confined discharge gaps. Hence, they can be used for direct treatment and there is also no limitation on the size of the object. However, to the best of our knowledge, the dimensions of plasma jet nozzles that have been reported in the literature are mainly very small (sub-millimeter to several millimeters) making treatment of a large area difficult, only few large plasma jets are developed. One way to overcome this shortcoming is the use of plasma jet arrays. However, since individual plasma plumes generated by these plasma jet arrays are independent and not merged, it is relatively difficult to achieve uniform treatment effects.

关键词： Brushes Surface treatment Plasma sources laboratories electromagnetics Educational institutions

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Communication modeling for wide-area relay protection based on IEC 61850

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Telkomnika - Indonesian Journal of Electrical engineering 2012年第7期10卷 1673-1684页

作者： Chen, Guoyan Yin, Xianggen Zhang, Kai The State Key Laboratory of Advanced Electromagnetic Engineering and Technology Huazhong University of Science and Technology Wuhan 430074 China

Wide-area communication system is supporting platform for wide-area relay protection (WARP) exchanging information, which includes not only visible physical communication equipment and links, but also communication protocols and other upper communication services. WARP communication has become an important issue in WARP practical applications, but it has not been described in IEC 61850 standard. To solve this issue, this paper firstly presents the general steps of WARP modeling according to the layer upon layer modeling methods of IEC 61850 standard, then proposes a tree structure model of master station and affiliate stations with information interaction model between master station and affiliate stations following IEC 61850 by taking a 220kV smart substation and WARP algorithm based on fault voltage distribution for example, finally establishes a communication model of WARP that includes client/server transfer model, electrical value transmission model and logical status variables transmission model. The fundamental purpose of constructing the communication model is to implement the interoperability between WARP-IED (WARP-Intelligent Electronic Devices) and other IEDs in a smart substation. © 2012 Universitas Ahmad Dahlan.

关键词： Trees (mathematics)

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Experimental investigation of surface flashover characteristics in vacuum

Experimental investigation of surface flashover characterist...

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IEEE Symposium Power Modulator

作者： Ling Dai Fuchang Lin Xiangyu Shi Xingchen Yao Yaohong Cheng Zhiwei Li Cheng Su State Key laboratory of Advanced Electromagnetic Engineering and Technology Huazhong University of Science and Technology Wuhan Hebei China

This paper devotes itself to the experimental study on surface flashover characteristics of insulating material, which is closely connected to the compact pulsed power system operating in vacuum. The rated voltage of the pulsed power source is several kV and the peak current is several kA. To simulate the actual operating condition and possible failure mode of pulsed power system, a series of experiments are performed to validate the adaptability of high pulsed power device in vacuum. This paper concentrates on the mechanism of surface flashover in vacuum and corresponding influence factors. Different metal electrode materials, different creepage distances and the interference effect of hot plasma have been studied. Research indicates that external plasma plays a key role in the formation of surface flashover. In medium vacuum (1×10 -3 Pa), the surface flashover voltage of 3mm surface creeping distance on organic glass is above 17 kV; But if there is external plasma source, the flashover voltage would reduce significantly with the increase of plasma density; flashover voltage would rush to 1 kV or lower. Based on the experiment study, some measures are taken on the several kilovolts pulsed power source (PPS) produced in prior work. The device can operate stably in the vacuum of 10 -3 Pa.

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A novel fault phase selector for double-circuit transmission lines

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Telkomnika - Indonesian Journal of Electrical engineering 2012年第7期10卷 1730-1738页

作者： Deng, Xing Yin, Xianggen Zhang, Zhe Kong, Xiangping Qiu, Cheng The State Key Laboratory of Advanced Electromagnetic Engineering and Technology Huazhong University of Science and Technology Wuhan 430074 China

A novel fault phase selector for double-circuit transmission lines is presented. The fault type is determined with the superimposed components and steady state components of fault voltage. According to the determined fault type, auxiliary criteria based on the magnitude and phase difference of fault phase current is applied to judge whether inter-line fault happens or not. If inter-line fault happens, the fault phase is determined by comprehensive criteria based on the comparison of current magnitude and the judgment of impedance direction. The simulation results verify the correction of the proposed phase selector. © 2012 Universitas Ahmad Dahlan.

关键词： Electric lines

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