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Design of an electron gun for terahertz radiation source

Chinese Physics C 2014年第4期38卷 93-97页

作者：李骥裴元吉胡桐宁陈曲珊冯光耀尚雷李成龙 National Synchrotron Radiation Laboratory University of Science and Technology of China State Key Laboratory of Advanced Electromagnetic Engineering and Technology Huazhong University of Science and Technology Deutsches Elektronen-Synchrotron

An EC-ITC （External-Cathode Independently Tunable Cells） RF gun was employed with the aim of obtaining short-pulse bunches with high peak current for a terahertz radiation source. A gridded DC gun plays a key role as the external injecting electron source of the ITC RF gun, the performance of which determines the beam quality in the injector and transport line. In order to make the beam well compressed in the ITC RF gun, the energy of the electrons acquired from the gridded DC gun should be 15 keV at most. A proper structure of the gridded gun with double-anode is shown to overcome the strong space- charge force on the cathode, which is able to generate 6 μs beam with 4.5 A current successfully.

关键词： gridded DC gun RF gun EC-ITC

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Sodium phytate stabilizing lattice oxygen in high-nickel oxide cathodes for thermal runaway inhibition and high voltage operation

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Science Bulletin 2025年

作者： Yuanke Wu Qiang Wu Ziqi Zeng Yixuan Dong Shijie Cheng Jia Xie State Key Laboratory of Advanced Electromagnetic Engineering and Technology School of Electrical and Electronic Engineering Huazhong University of Science and Technology Wuhan 430074 China State Key Laboratory of Materials Processing and Die & Mould Technology School of Materials Science and Engineering Huazhong University of Science and Technology Wuhan 430074 China

The reactive oxygen species (O*) released from the nickel-rich layered oxide cathodes (LiNi x Co y Mn 1− x − y O 2 , NCM) are responsible for triggering thermal runaway (TR) in lithium-ion batteries (LIBs). Specifically, the charge compensation from transition metal (TM) 3d to oxygen (O) 2p in NCM plays a pivotal role in O* release. Here, inspired by the strong chelating effect of sodium phytate (PN) on TM, we employ PN as a cathode additive to coordinate with nickel, thereby weakening the charge compensation of TM 3d to O 2p on the surface of LiNi 0.8 Co 0.1 Mn 0.1 O 2 (NCM811) and ultimately enhancing battery safety. It is shown that the chelation successfully stabilizes lattice oxygen and suppresses the release of O*, preventing detrimental phase transitions in NCM811 and reducing heat generation from O* related crosstalk reactions. Consequently, the TR trigger temperature ( T tr ) of NCM811 pouch cell with PN elevates from 125.9 to 184.8 °C, while the maximum temperature ( T max ) decreases from 543.7 to 319.7 °C. Moreover, the PN-derived modification layer allows NCM811 to maintain exceptional cycling stability for over 700 cycles at 4.6 V. This strategy provides a facile method for stabilizing lattice oxygen in NCM, inhibiting O*-triggered TR, and enhancing high-voltage performance.

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Modeling and Analysis for Practical CT Based on Transient Test and Parameter Identification

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CSEE Journal of Power and Energy Systems 2016年第4期2卷 51-57页

作者： Xianggen Yin Zhe Zhang Xuanwei Qi Gan Li Wenbin Cao Qian Guo State Key Laboratory of Advanced Electromagnetic Engineering and Technology Huazhong University of Science and TechnologyWuhan 430074China

In the transient process of power grid faults,the transferring distortion of current transformer(CT)can seriously affect relay protection *** these conditions,it is difficult to analyze the ferromagnetic characteristic of the magnetizing branch in the transient equivalent circuit of *** Jiles-Atherton hysteresis model(J-A model),which is widely used in digital simulations,can accurately describe the hysteresis and saturation process of the core characteristics;however,to acquire the parameters of the J-A model of current transformers in practical use is still a challenging *** this paper,physical tests based on a practical CT and parameter identification are presented to solve the *** basic hysteresis loops of P,PR,and TPY class of practical current transformers are obtained through physical ***,the J-A model parameters are identified using a hybrid genetic/simulated annealing algorithm,based on which transient simulation models of different class CTs are *** effectiveness of the proposed method is verified via dynamic physical simulation tests.A typical accident is analyzed based on these models.

关键词： Current transformer dynamic physical simulation tests J-A model parameter identification transient test

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Phase–amplitude model for doubly fed induction generators

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Journal of Modern Power Systems and Clean Energy 2019年第2期7卷 369-379页

作者： Hua HUANG Ping JU Xueping PAN Yuqing JIN Xiaoming YUAN Yuan GAO State Key Laboratory of Advanced Electromagnetic Engineering and Technology School of Electrical and Electronic EngineeringHuazhong University of Science and TechnologyWuhan 430074China College of Energy and Electrical Engineering Hohai UniversityNanjing 210098China

The doubly fed induction generator(DFIG) is major type of wind turbine generator used in grid-connected wind farms. Practical models of DFIG have been built to study the influence of wind power generation on power system dynamics. However, most existing practical models of the DFIG are based on rectangular coordinates,in which frequency variation is neglected. In this paper, a phase-amplitude(P-A) model is proposed for a DFIG based on phase and amplitude of the internal voltage. The model structure is much like that of the synchronous generator, and the rotor voltage can manipulate both the amplitude and the phase of the internal *** have been made between the new P-A model of the DFIG and the synchronous generator model,as well as the asynchronous motor *** contributions of the new P-A model of the DFIG are discussed and it is demonstrated that the proposed model has better ability in describing power system dynamic phenomena such as voltage dynamics and structural dynamics. Simulation results and a field test validate these contributions.

关键词： Doubly fed induction generator(DFIG) Model Internal voltage Voltage dynamics Frequency dynamics

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TOV in SMs during MMC riding through zero DC voltage fault: Analysis and suppression

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Journal of engineering 2016年第11期2016卷 386-393页

作者： Hu, Jiabing Lu, Maozeng Lin, Lei State Key Laboratory of Advanced Electromagnetic Engineering and Technology Huazhong University of Science and Technology Wuhan430074 China

A comprehensive analysis and a suppression method of sub-modules' (SMs') transient over-voltage (TOV) in a hybrid modular multilevel converter are presented, consisting of half half-bridge SMs and half full-bridge SMs, during riding through zero DC voltage faults. Analytical expressions of SMs' TOV are initially explored. The relations among transient voltages of SMs in six arms with the same fault moment and those in a fixed arm with different fault moments are deduced. Furthermore, the maximum value of SMs' transient voltages dependent on the fault moment is also presented. A suppression method using common-mode voltage injection is proposed without sacrificing the performance of the converter on riding through zero DC voltage faults. Simulated results are provided to demonstrate the validity of the analytical results and the feasibility of the proposed suppression scheme. © 2016, Institution of engineering and technology. All rights reserved.

关键词： Power quality

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Error field penetration in J-TEXT tokamak based on two-fluid drift-MHD model

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Chinese Physics B 2024年第4期33卷 545-551页

作者：王文徐涛张仪 the J-TEXT team State Key Laboratory of Advanced Electromagnetic Technology International Joint Research Laboratory of Magnetic Confinement Fusion and Plasma PhysicsSchool of Electrical and Electronic EngineeringHuazhong University of Science and TechnologyWuhan 430074China

An externally generated resonant magnetic perturbation can induce complex non-ideal MHD responses in their resonant *** have studied the plasma responses using Fitzpatrick's improved two-fluid model and program *** calculated the error field penetration threshold for *** addition,we find that the island width increases slightly as the error field amplitude increases when the error field amplitude is below the critical penetration ***,the island width suddenly jumps to a large value because the shielding effect of the plasma against the error field disappears after the *** scanning the natural mode frequency,we find that the shielding effect of the plasma decreases as the natural mode frequency ***,we obtain the m/n=2/1 penetration threshold scaling on density and temperature.

关键词： plasma responses drift-MHD model error field penetration

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Experimental Studies of Electrostatic Fluctuations and Turbulent Transport in the Boundary of J-TEXT Tokamak Using Reciprocating Probe

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Plasma Science and technology 2012年第12期14卷 1041-1047页

作者： CHEN Zhipeng SUN Yue WANG Zhijiang YANG Zhoujun DING Yonghua ZHUANG Ge J-TEXT team State Key Laboratory of Advanced Electromagnetic Engineering and Technology Huazhong University of Science and Technology Wuhan 430074 China Key Laboratory of Geospace Environment Chinese Academy of Sciences University of Science & Technology of China Hefei 230026 China

As the basic of a deeper investigation on the turbulent transport, the fluctuation property in the boundary of the newly-reconstructed Joint Texas Experimental Tokamak （J- TEXT） is studied experimentally using the reciprocating Langmuir four-tip probe, which has been built and operated as the primary diagnostic tool in the boundary of J-TEXT tokamak. In this paper, spatial profiles of the plasma-edge parameters are obtained, such as electron temperature, plasma density, plasma potential, poloidal electric field and their fluctuations. The results indicate the existence of a Er ×BT shear layer at the vicinity of last closed flux surface （LCFS）, with the fluctuations suppressed in varying degrees. The turbulence-induced particle and energy fluxes can be calculated by the local plasma parameters above. Convection dominates the cross-field turbulent transport in boundary plasma. Electrostatic fluctuations properties are also studied in detail with the help of numerical analysis. Statistical analysis on density fluctuation shows that, the intermittency can affect the turbulence in the scrape-off layer （SOL）.

关键词： electrostatic fluctuations anomalous transport J-TEXT reciprocating Lang- muir probe

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AtomGAN:unsupervised deep learning for fast and accurate defect detection of 2D materials at the atomic scale

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Science China(Information Sciences) 2023年第6期66卷 102-114页

作者： Danpeng CHENG Wuxin SHA Zuo XU Shide LI Zhigao YIN Yuling LANG Shun TANG Yuan-Cheng CAO State Key Laboratory of Advanced Electromagnetic Engineering and Technology School of Electrical and Electronic EngineeringHuazhong University of Science and Technology School of Computer Science and Technology Huazhong University of Science and Technology CITIC Dicastal Co. Ltd.

The extraction of atomic-level material features from electron microscope images is crucial for studying structure-property relationships and discovering new materials. However, traditional electron microscope analyses rely on time-consuming and complex human operations; thus, they are only applicable to images with a small number of atoms. In addition, the analysis results vary due to observers' individual deviations. Although efforts to introduce automated methods have been performed previously, many of these methods lack sufficient labeled data or require various conditions in the detection process that can only be applied to the target material. Thus, in this study, we developed AtomGAN, which is a robust, unsupervised learning method, that segments defects in classical 2D material systems and the heterostructures of MoS2/WS2automatically. To solve the data scarcity problem, the proposed model is trained on unpaired simulated data that contain point and line defects for MoS2/WS2. The proposed AtomGAN was evaluated on both simulated and real electron microscope images. The results demonstrate that the segmented point defects and line defects are presented perfectly in the resulting figures, with a measurement precision of 96.9%. In addition, the cycled structure of AtomGAN can quickly generate a large number of simulated electron microscope images.

关键词： deep learning generative adversarial network defect detection atomic resolution 2D materials

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Research progresses of cathodic hydrogen evolution in advanced lead–acid batteries

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Science Bulletin 2016年第6期61卷 451-458页

作者： Feng Wang Chen Hu Min Zhou Kangli Wang Jiali Lian Jie Yan Shijie Cheng Kai Jiang State Key Laboratory of Advanced Electromagnetic Engineering and Technology School of Materials Science and EngineeringHuazhong University of Science and TechnologyWuhan 430074 China China Electric Power Research Institute Beijing 100192 China

Integrating high content carbon into the negative electrodes of advanced lead–acid batteries effectively eliminates the sulfation and improves the cycle life,but brings the problem of hydrogen evolution,which increases inner pressure and accelerates the water *** this review,the mechanism of hydrogen evolution reaction in advanced lead–acid batteries,including lead–carbon battery and ultrabattery,is briefly *** strategies on suppression hydrogen evolution via structure modifications of carbon materials and adding hydrogen evolution inhibitors are summarized as *** review points out effective ways to inhibit hydrogen evolution and prolong the cycling life of advanced lead–acid battery,especially in high-rate partial-state-of-charge applications.

关键词： Lead–carbon battery Ultrabattery Hydrogen evolution reaction Hydrogen inhibition

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Construction of LiCl/LiF/LiZn hybrid SEI interface achieving high-performance sulfide-based all-solid-state lithium metal batteries

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Science China Chemistry 2024年第6期67卷 1990-2001页

作者： Chaochao Wei Yujie Xiao Zhongkai Wu Chen Liu Qiyue Luo Ziling Jiang Lin Li Liang Ming Jie Yang Shijie Cheng Chuang Yu State Key Laboratory of Advanced Electromagnetic Technology School of Electrical and Electronic EngineeringHuazhong University of Science and TechnologyWuhan430074China School of Chemistry and Chemical Engineering Huazhong University of Science and TechnologyWuhan430074China

Sulfide-based all-solid-state lithium metal batteries(ASSLMBs)have received extensive attention due to their high energy density and high safety,while the poor interface stability between sulfide electrolyte and lithium metal anode limits their ***,a hybrid SEI(LICl/Li F/Li Zn)was constructed at the interface between Li_(5.5)PS_(4.5)Cl_(1.5)sulfide electrolyte and lithium *** Li Cl and Li F interface phases with high interface energy effectively induce the uniform deposition of Li^(+)and reduce the overpotential of Li^(+)deposition,while the Li Zn alloy interface phase accelerates the diffusion of lithium *** synergistic effect of the above functional interface phases inhibits the growth of lithium dendrites and stabilizes the interface between the sulfide electrolyte and lithium *** hybrid SEI strategy exhibits excellent electrochemical performance on symmetric batteries and all-solid-state *** symmetrical cell exhibits stable cycling performance over long duration over 500 h at 1.0 mA cm^(-2).Moreover,the LiNbO_(3)@NCM712/Li_(5.5)PS_(4.5)Cl_(1.5)/Li-10%Zn F_(2)battery exhibits excellent cycle stability at a high rate of 0.5 C,with a capacity retention rate of 76.4%after 350 cycles.

关键词： argyrodite electrolytes ASSLMBs electrochemical stability Li-ZnF_2 anode electrochemical performance

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