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Facile synthesis of Li2S@C composites as cathode for Li–S batteries

Journal of Energy Chemistry 2019年第10期28卷 111-116页

作者： Xin Chen Linfeng Peng Lixia Yuan Rui Zeng Jingwei Xiang Weilun Chen Kai Yuan Jie Chen Yunhui Huang Jia Xie State Key Laboratory of Advanced Electromagnetic Engineering and Technology School of Electrical and Electronic EngineeringHuazhong University of Science and TechnologyWuhan 430074HubeiChina State Key Laboratory of Materials Processing and Die & Mould Technology School of Materials Science and EngineeringHuazhong University of Science and TechnologyWuhan 430074HubeiChina

Lithium sulfide (Li2S) provides a promising route for lithium storage due to high theoretical specific capacity (1166 mAh g-1). The electrochemical performance of Li2S can be significantly enhanced by forming Li2S-carbon composites with the introduction of carbon. However, the complex synthesis method of Li2S-carbon composites restrains the large-scale productivity. Herein, we propose a facile route to prepare carbon coated Li2S-carbon nanotube composites (Li2S@C-CNT) via spray drying and heat treatment, which is a low-cost and large-scale method for facile synthesis of Li2S-carbon composites. For the Li2S@C-CNT composites, Li2S nanoparticles are contacted with surrounding particles due to the 3D CNTs framework. The novel construction not only suppresses the diffusion of polysulfides during cycling, but also remarkably accelerates the transport of electron and ion, resulting in a high specific capacity (1100 mAh g^-1) and good cycling performance. The rational designed architecture and good electrochemical performance of Li2S@C-CNT will pave the avenue for realizing high energy density of Li2S-based batteries.

关键词： Spray drying Li2S@C-CNT Lithium-sulfur batteries

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A Prediction Model for Time Series of Dissolved Gas Content in Transformer Oil Based on LSTM

A Prediction Model for Time Series of Dissolved Gas Content ...

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作者： Chuye Hu Yang Zhong Yiqi Lu Xiaotong Luo Shaorong Wang State Key Laboratory of Advanced Electromagnetic Engineering and Technology Huazhong University of Science &Technology

By combining with dissolved gas analysis,time series prediction of dissolved gas content in oil provides a basis for transformer fault diagnose and early warning. In the view of that,a prediction model based on long short time memory(LSTM) network for time series of dissolved gas content in oil is proposed,which takes advantage of LSTM network's ability to deal with long-sequence prediction problems. Five characteristic gas concentrations are used as input to the model,and the hyper parameters of the model is optimized by Bayesian optimization algorithm to further improve prediction accuracy,then a LSTM prediction model is constructed. By case study,it is verified that the proposed model can precisely predict time series of dissolved gas content. Compared with gray model,BP neural network and support vector machine,the proposed model has higher prediction accuracy and can better track the trend of time series of dissolved gas content in oil.

关键词： A Prediction Model for Time Series of Dissolved Gas Content in Transformer Oil Based on LSTM Model

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engineering design of step-up transformer for inverter type high voltage DC power supply

Engineering design of step-up transformer for inverter type ...

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2020 IEEE Sustainable Power and Energy Conference, iSPEC 2020

作者： Zhang, Hongqi Zhou, Lan Ma, Shaoxiang Zhang, Ming Wang, Dongyu Yu, Kexun Pan, Yuan State Key Laboratory of Advanced Electromagnetic Engineering and Technology Huazhong University of Science and Technology Wuhan China State Grid Electric Power Co. Ltd. Yichang Power Supply Company Yichang China

ISBN: (纸本)9781728191645

The neutral beam injection system in the Chinese Fusion engineering Test Reactor(CFETR) is used for auxiliary heating of the plasma, it is necessary to create an acceleration grid power supply to provide energy for the plasma. The high voltage power supply adopts the inverter type power supply scheme, in which the step-up transformer plays the role of voltage isolation and power transformation between the primary and secondary sides, and is the key equipment to determine the voltage level and safety of the high voltage power supply. In addition to the general characteristics of large capacity and high voltage class, the transformer also needs to meet the requirements of operating under unusual frequency and high harmonic input. According to the requirements of step-up transformer, this paper reports the engineering design of the transformer, including the calculation of key parameters, the design of the main electromagnetic structure, such as core and winding of transformer, simulation of transformer insulation level for the standard input voltage, research about winding loss and temperature rise caused by higher harmonic. It lays the foundation for the future construction of CFETR N-NBI system. © 2020 IEEE.

关键词： DC transformers

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Optimizing Layout of Video Surveillance for Substation Monitoring

Optimizing Layout of Video Surveillance for Substation Monit...

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作者： Yiqi Lu Yang Zhong Chuye Hu Shaorong Wang State Key Laboratory of Advanced Electromagnetic Engineering and Technology Huazhong University of Science and Technology

An automated video surveillance system plays a vital role in unattended substations. To minimize the camera cost and maximize the monitoring coverage of the substation, efficiently placing the camera is critical. Two optimization models are developed in this paper to satisfy two kinds of requirements of unattended substations monitoring in practice: minimizing cost with full coverage, optimizing coverage with a fixed budget. The second model is mainly proposed for the first time to get the minimum monitoring fitness function as the optimization goal. By introducing piecewise functions in the second model, it meets different monitor-ing requirements in different regions of substations and reduces the over-lapping monitoring area efficiently. The two models are tested using a genetic algorithm to get the optimal layout of the cameras. The validity and practicability of the two models of monitoring in unattended substations are verified by simulation. The results suggest that this model-based optimization approach to cameras layout can be used to improve the efficiency of substation video surveillance systems.

关键词： Optimization model Automated video surveillance Genetic algorithm Substation monitoring Set covering problem

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A Three-Stage Ensemble Short-Term Wind Power Prediction Method Based on VMD-WT Transform and SDAE Deep Learning

A Three-Stage Ensemble Short-Term Wind Power Prediction Meth...

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2020 IEEE/IAS Industrial and Commercial Power System Asia, I and CPS Asia 2020

作者： Xiaosheng, Peng Zuowei, Zhang Qiyou, Xu Bo, Wang Jianfeng, Che Fan, Yang Wenze, Li Zian, Huang Huazhong University of Science and Technology State Key Laboratory of Advanced Electromagnetic Engineering and Technology School of Electrical and Electronic Engineering Wuhan430074 China China Electric Power Research Institute State Key Laboratory of Operation and Control of Renewable Energy Storage Systems Beijing100192 China

ISBN: (纸本)9781728143033

Accurate wind power prediction (WPP) will contribute not only to the economic dispatching of power system but also to the safe and stable operation of the power grid. A novel three-stage ensemble short-term WPP method is proposed in this paper to effectively improve the WPP accuracy. First, in stage one, variational mode decomposition (VMD) and wavelet transform (WT) are applied to decompose the original wind power sequence into multiple subsequences. Second, in stage two, multiple stacked denoising auto-encoders (SDAE) are constructed based on the subsequences to perform WPPs separately. Third, in stage three, and the support vector machine (SVM) is applied to assign weights to each sub-prediction value to obtain the final ensemble prediction result. The case study shows that, compared with back propagation neural network (BPNN) and SVM, the average normalized root mean square error (NRMSE) and normalized mean absolute error (NMAE) of proposed ensemble WPP method, in the step range of12 hours, are reduced by 19.66% and 19.91% compared to BPNN, and 14.43% and 14.65% compared to SVM, respectively, which illustrates the effectiveness and advancement of the proposed method. © 2020 IEEE.

关键词： Variational mode decomposition

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Observation of intrinsic crystal phase in bare CrI3 ferromagnetism

arXiv

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arXiv 2022年

作者： Liu, Zhen Guo, Yongzheng Chen, Zhiyong Gong, Tao Li, Yue Niu, Yuting Cheng, Yingchun Lu, Haipeng Deng, Longjiang Peng, Bo National Engineering Research Center of Electromagnetic Radiation Control Materials School of Electronic Science and Engineering University of Electronic Science and Technology of China Chengdu611731 China State Key Laboratory of Electronic Thin Films and Integrated Devices University of Electronic Science and Technology of China Chengdu611731 China Key Laboratory of Flexible Electronics Institute of Advanced Materials Jiangsu National Synergetic Innovation Center for Advanced Materials Nanjing Tech University Nanjing211816 China

Intrinsic structural phase is a crucial foundation for the fundamental physical properties, and for creating innovative devices with unprecedented performances and unique functionalities. Long-range ferromagnetic orders of van der Waals CrI3 are strongly tied with interlayer stacking orders. However, the intrinsic structure of few-layer CrI3 still remains elusive;the predicted monoclinic phase has not yet been experimentally detected in bare few-layer CrI3. Here we uncover the intrinsic structure of few-layer CrI3 with interlayer antiferromagnetic coupling, which unambiguously show monoclinic stacking in both bare and hBN-encapsulated bilayer and tri-five-layer CrI3 throughout an entire temperature range from 300 to 10 K. An exotic spring damping effect from hBN encapsulation layers is experimentally observed in hBN/CrI3/hBN heterostructures, which partly hinders interlayer sliding of CrI3. This work demonstrates the intrinsic monoclinic crystal phase of few-layer CrI3 and associated correlation with magnetic orders, opening up numerous opportunities for creating magnetic texture by stacking design. © 2022, CC BY.

关键词： Chromium compounds

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Critical Current Density and AC Magnetic Susceptibility of High-quality FeTe0.5Se0.5 Superconducting Tapes

arXiv

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arXiv 2025年

作者： Zhou, Xin Li, Wenjie Hou, Qiang Wei, Wei Liu, Wenhui Wang, Ke Xing, Xiangzhuo Liu, Linfei Ge, Jun-Yi Qi, Yanpeng Liu, Huajun Ren, Li Tamegai, Tsuyoshi Sun, Yue Shi, Zhixiang School of Physics Southeast University Nanjing211189 China Department of Applied Physics The University of Tokyo Tokyo113-8656 Japan School of Physics and Physical Engineering Qufu Normal University Qufu273165 China School of Physics and Astronomy Shanghai Jiao Tong University Shanghai200240 China Materials Genome Institute Shanghai University Shanghai200444 China School of Physical Science and Technology ShanghaiTech University Shanghai201210 China Institute of Plasma Physics Chinese Academy of Sciences Anhui Hefei230031 China State Key Laboratory of Advanced Electromagnetic Engineering and Technology School of Electrical and Electronic Engineering Huazhong University of Science and Technology Wuhan430030 China

Iron telluride-selenium superconducting materials, known for their non-toxicity, ease of preparation, simple structure, and high upper critical fields, have attracted much research interest in practical application. In this work, we conducted electrical transport measurements, magneto-optical imaging, and AC magnetic susceptibility measurements on FeTe0.5Se0.5 superconducting long tapes fabricated via reel-to-reel pulsed laser deposition. Our transport measurements revealed a high critical current density that remains relatively stable even with increasing external magnetic fields, reaching over 1 × 105 A/cm2 at 8 K and 9 T. The calculated pinning force density indicates that normal point pinning is the primary mechanism in these tapes. The magneto-optical images demonstrated that the tapes show homogeneous superconductivity and uniform distribution of critical current density. The AC magnetic susceptibility measurements also confirmed their strong flux pinning nature of withstanding high magnetic field. Based on these characteristics, FeTe0.5Se0.5 superconducting tapes show promising prospects for applications under high magnetic field. © 2025, CC BY.

关键词： Superconducting tapes

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Short-Term Wind Power Prediction Based on Wavelet Transform and Convolutional Neural Networks

Short-Term Wind Power Prediction Based on Wavelet Transform ...

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2020 IEEE/IAS Industrial and Commercial Power System Asia, I and CPS Asia 2020

作者： Xiaosheng, Peng Kai, Cheng Bo, Wang Jianfeng, Che Qiyou, Xu Fan, Yang Wenze, Li Huazhong University of Science and Technology State Key Laboratory of Advanced Electromagnetic Engineering and Technology School of Electrical and Electronic Engineering Wuhan430074 China State Key Laboratory of Operation and Control of Renewable Energy Storage Systems China Electric Power Research Institute Beijing100192 China

ISBN: (纸本)9781728143033

Wind power prediction (WPP) is critical to the safe operation and economic dispatch of power systems, but it faces two challenges: 1) Information on different frequency bands is included in the numerical weather prediction (NWP) data, making it difficult to mine vital information if the original NWP data is directly applied as input data;2) There is a strong nonlinear relationship between the input and output data in the WPP model, meaning that traditional models are difficult to fit accurately. This paper proposes a new short-term WPP model based on wavelet transform (WT) and convolutional neural networks (CNN). First, WT is applied to split the original NWP data and historical power data into multiple sets of different frequency components. Then, based on the NWP and historical power data sets of relevant frequencies, CNN models are established for prediction. Finally, based on the prediction results of different frequency components, inverse WT is applied to reconstruct the WPP results. This case study shows that 1) the WT method allows for effective mining of the information contained in the different frequency components of the NWP data;and 2) when the WT-CNN model is applied to predict the wind power in the next 12 hours, the NRMSE of the model is reduced by 1.55 percentage points compared with Back Propagation Neural Network. © 2020 IEEE.

关键词： Wavelet transforms

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Robust Nonlinear Adaptive Pressure Control of Polymer Electrolyte Membrane Fuel Cells Considering Sensor Failures

SSRN

引用

SSRN 2022年

作者： Chen, Jian Yao, Wei Lu, Qun Duan, Xiaohui Yang, Boping Zhu, Fengyu Cao, Xuexiang Jiang, Lin School of Electrical Engineering Yancheng Institute of Technology Yancheng224051 China State Key Laboratory of Advanced Electromagnetic Engineering and Technology School of Electrical and Electronics Engineering Huazhong University of Science and Technology Wuhan430074 China Southwest Equipment Research Institute Co. Ltd Chongqing401121 China Department of Electrical Engineering and Electronics University of Liverpool LiverpoolL69 3GJ United Kingdom

This paper proposes a robust nonlinear adaptive pressure control (RNAPC) employing perturbation estimation technique to lengthen the life of the polymer electrolyte membrane fuel cells (PEMFCs). Since large deviations between the partial pressure of oxygen and hydrogen can lead to severe membrane damage, a robust and adaptive nonlinear control method needs to be designed for suppressing the deviations. Due to high nonlinearities, uncertainties, load disturbance and sensor failures in the PEMFCs, neither a traditional PI control nor feedback linearization control (FLC) can always provide satisfactory performances. In the design of RNAPC, an observer is designed to estimate a perturbation term containing system uncertainties, nonlinearities and disturbances. The estimation of perturbation is used for the compensation of actual perturbation. Then, an adaptive FLC of PEMFC system can be realized. Therefore, the RNAPC requires only few state measurements and is independent of accurate system model. Simulation results show that the RNAPC method has smaller deviations of partial pressure of oxygen and hydrogen and better dynamic performance than traditional PI control under load disturbance, and obtains higher robustness against uncertainties and sensor failures than traditional PI control and FLC. © 2022, The Authors. All rights reserved.

关键词： Proton exchange membrane fuel cells (PEMFC)

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Soft landing of runaway currents by ohmic field in J-TEXT tokamak

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Plasma Science and technology 2020年第11期22卷 11-22页

作者： Jie HU Wei YAN Ruihai TONG Wei LI Zhongyong CHEN Anjue DAI Duwei HUANG Yunong WEI Tiankui MA Yuan HUANG Yang LI Wei ZHENG Zhifang LIN You LI Huaiyu YANG Duoqin WANG Wei BAI Yu ZHONG Jiangang FANG J-TEXT Team International Joint Research Laboratory of Magnetic Confinement Fusion and Plasma Physics State Key Laboratory of Advanced Electromagnetic Engineering and TechnologySchool of Electrical and Electronic EngineeringHuazhong University of Science and Tech no logyWuhan 430074People's Republic of China Southwestern Institute of Physics Chengdu 610041.People's Republic of China Chengdu University Chengdu 610106People's Republic of China Beibu Gulf University Qinzhou 535000People's Republic of China

Recently,experimental studies on the soft landing of RE current by ohmic(OH)field have been performed in J-TEXT tokamak,as a possible auxiliary method to dissipate the RE *** optimized horizontal displacement control of the RE beam,the toroidal electric field has been scanned from 1.6 to—0.3 V m^-1 during the RE plateau *** growth rate of RE currents and the evolution of hard x-ray(HXR)emissions have been *** is found that when the toroidal electric field is less than 7-12 times the theoretical critical electric field,the decay of REs could be *** dissipation rate by the ohmic field can reach a maximum value of 3 MA s^-***,the results of HXR spectra analysis indicate the different behaviors of HXR emissions under the condition of different toroidal electric *** analysis of the ionized argon emissions and magnetic fluctuations shows that under the condition of different toroidal electric fields,the physical process of RE generation may be different.

关键词： tokamak disruption runaway electron hard x-ray

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