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Observation of non-local effects in ion transport channel in J-TEXT plasmas

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arXiv 2018年

作者： Shi, Yuejiang Yang, Zhoujun Chen, Zhongyong Cheng, Zhifeng Zhang, Xiaoyi Yan, Wei Wen, Jie Cai, Qinxue Zhao, Kaijun Hong, Seulchan Kwon, JaeMin Diamond, Partick H. Shi, Peng Zhou, Hao Pan, Xiaoming Chen, Zhipeng Yang, SeongMoo Dong, Yunbo Wang, Lu Ding, YongHua Liang, Yunfeng Shi, Zhongbin Na, Yong-Su Department of Nuclear Engineering Seoul National University Seoul Korea Republic of International Joint Research Laboratory of Magnetic Confinement Fusion and Plasma Physics State Key Laboratory of Advanced Electromagnetic Engineering and Technology School of Electrical and Electronic Engineering Huazhong University of Science and Technology Wuhan China College of Nuclear Science and Engineer East China University of Technology Nanchang China National Fusion Research Institute Daejeon Korea Republic of Southwestern Institute of Physics Chengdu China CMTFO and CASS University of California San Diego United States Jülich Germany

In cold pulse experiments in J-TEXT, the ion transport shows similar non-local response as the electron transport channel. Very fast ion temperatures decreases are observed in the edge, while the ion temperature in core promptly begin to rise after the injection of cold pulse. Moreover, the cutoff density is also found for the ion non-local effect. The experimental observed density fluctuation in a high frequency ranging from 500 kHz to 2 MHz is obviously reduced in the whole plasma region during non-local transport (NLT) phase. Copyright © 2018, The Authors. All rights reserved.

关键词： Electron transport properties

Revoking amplitude and oscillation deaths by low-pass filter in coupled oscillators

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Physical Review E 2017年第6期95卷 062206-062206页

作者： Wei Zou Meng Zhan Jürgen Kurths Department of Physics Hong Kong Baptist University Kowloon Tong Hong Kong SAR People's Republic of China State Key Laboratory of Advanced Electromagnetic Engineering and Technology School of Electrical and Electronic Engineering Huazhong University of Science and Technology Wuhan 430074 People's Republic of China Potsdam Institute for Climate Impact Research Telegraphenberg Potsdam D-14415 Germany Institute of Physics Humboldt University Berlin Berlin D-12489 Germany Department of Control Theory Nizhny Novgorod State University Gagarin Avenue 23 606950 Nizhny Novgorod Russia

When in an ensemble of oscillatory units the interaction occurs through a diffusion-like manner, the intrinsic oscillations can be quenched through two structurally different scenarios: amplitude death (AD) and oscillation death (OD). Unveiling the underlying principles of stable rhythmic activity against AD and OD is a challenging issue of substantial practical significance. Here, by developing a low-pass filter (LPF) to track the output signals of the local system in the coupling, we show that it can revoke both AD and OD, and even the AD to OD transition, thereby giving rise to oscillations in coupled nonlinear oscillators under diverse death scenarios. The effectiveness of the local LPF is proven to be valid in an arbitrary network of coupled oscillators with distributed propagation delays. The constructive role of the local LPF in revoking deaths provides a potential dynamic mechanism of sustaining a reliable rhythmicity in real-world systems.

关键词： Coupled oscillators

CoFMD-BiLSTM: A Wind and Photovoltaic Power Prediction Method Based on Feature Mode Decomposition and Cooperative Learning Strategy

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CoFMD-BiLSTM: A Wind and Photovoltaic Power Prediction Metho...

Chinese Automation Congress (CAC)

作者： Xinzhi Ding Dayi Li Wei Huang Yiping Chen State Key Laboratory of Advanced Electromagnetic Technology School of Electrical and Electronic Engineering Huazhong University of Science and Technology Wuhan Yunnan electric power test and Research Institute (Group) Co. Kunming Yunnan Power Grid Co. Ltd. Kunming Novel Electric Power System (Beijing) Research Institute of China Southern Power Grid Beijing China

ISBN: (数字)9798350368604

ISBN: (纸本)9798350368611

With the increasing penetration of new energy sources such as wind and solar, accurate source-side power forecasting helps power system dispatchers to obtain new energy pre-output plans and improve the power system's new energy consumption capacity through the coordination of multiple power generation resources. The wind and photovoltaic power data are characterized by large fluctuations, strong nonlinearity, instability, and strong time dependence, etc. Through “Decomposition-Prediction”, the original sequence is decomposed into a number of sub-sequences, which reduces the volatility and randomness of the original sequence, and has been widely used in wind and photovoltaic power prediction. In order to solve the problem that traditional decomposition algorithms have insufficient decomposition capability to extract data features in a targeted and effective way, we propose a wind and photovoltaic power prediction method based on Feature Mode Decomposition and Cooperative Learning Strategy: the CoFMD-BiLSTM model. A novel emerging decomposition algorithm, Feature Mode Decomposition (FMD), originally applied in fault detection, is introduced. By designing a Cooperative Learning Strategy to learn and fit the decomposition sequence information obtained from the FMD decomposition covering different features, which is fed into the BiLSTM model to obtain the wind and light power predictions. The actual operation data of Sotavento Galicia (sg) wind farm in Spain and TuoZhuo photovoltaic farm in Yunnan, China are used. Compared with the two models, VMD-BiLSTM and BiLSTM, the validation results show that the wind and solar power prediction method based on the CoFMD-BiLSTM model can effectively improve the accuracy of wind and solar power prediction.

关键词： Photovoltaic systems Bidirectional long short term memory Predictive models Wind power generation Wind farms Feature extraction Prediction algorithms Data models Wind forecasting Forecasting

General Diagnosis of Transformer Winding Axial Displacement Faults Based on FEM Simulation and On-site Experiments

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General Diagnosis of Transformer Winding Axial Displacement ...

IEEE Electrical Insulation Conference

作者： Fei Lu Lei Jin Siwei Liu Yi Liu Hua Li Fuchang Lin State Grid Key Laboratory of On-site Test Technology on High Voltage Power Apparatus State Grid Hubei Electric Power Research Institute State Key Laboratory of Advanced Electromagnetic Engineering and Technology Huazhong University of Science & Technology

ISBN: (纸本)9781467387071

Structural faults detection of power transformers are quite significant, and general diagnosis based on different test and simulation methods is commonly used to detect mechanical and/or electrical faults in power transformers. In this paper, the diagnosis of the transformer winding axial displacement faults based on FEM simulation and on-site experiment is carried out and presented. Based on the FEM simulation, it is necessary to analyze the effect of the axial displacement faults on the change of the electrical parameters. The whole winding's or the single disk's axial displacement are under consideration, and different fault levels are taken into consideration in the simulation analysis to investigate the influence of axial displacement on the electrical parameters. Using the calculated parameters, a distributed model of the power transformer based on ATP/EMTP is present to study the performance of frequency response curve on the axial displacement with different fault levels. The operating states of several 110 kV power transformers are tracked, and a typical transformer after the short-circuit impact is tested. The FRA test results are obtained before and after the short-circuit impact. The simulation results and the on-site test results are compared, and they show a better consistency. It can be concluded that under the typical impact of the axial displacement, the frequency response curve starts an obvious variation from 150 kHz, and the resonances and anti-resonances are shifted to the high frequency direction. The overall fault detection results show that the proposed method can discriminate the winding axial displacement fault with the high hit ratio.

关键词： Power transformer Frequency response analysis Axial displacement Winding deformation Finite element method

High-performance Ba1-xKxFe2As2 superconducting joints for persistent current operation

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arXiv 2021年

作者： Zhu, Yanchang Wang, Dongliang Wang, Qiqi Guo, Wenwen Liu, Cong Huang, He Ma, Hongjun Liu, Fang Liu, Huajun Ma, Yanwei Key Laboratory of Applied Superconductivity Institute of Electrical Engineering Chinese Academy of Sciences Beijing100190 China University of Chinese Academy of Sciences Beijing100049 China Institute of Electrical Engineering and Advanced Electromagnetic Drive Technology Qilu Zhongke Jinan250013 China School of Materials Science and Engineering Zhengzhou University Zhengzhou450001 China Institute of Plasma Physics Chinese Academy of Sciences Hefei230031 China

Superconducting joints are one of the key technologies to make Ba1-xKxFe2As2 (Ba-122) superconducting wires or tapes for high-field applications. Herein, superconducting joints were fabricated by a simple cold-pressing method, and the joint resistance of the iron-based superconducting joint was estimated for the first time. The superconducting properties, microstructures, and elements distribution in the joint regions were investigated. At 4.2 K and 10 T, a transport critical current Ic of 105 A for the joint was obtained, and the critical current ratio (CCR = Ijointc/Itapec) of the joint was 94.6%. On the other hand, the joint show very low joint resistance of 2.7× 10-13 Ω in self-field at 4.2 K. Among iron-based superconductors (IBS), this work is the first to successfully realize a superconducting joint with such high CCR and low joint resistance. This work shows great potential to apply Ba-122 in a range of practical applications, where superconducting joints are essential. © 2021, CC BY.

关键词： Iron-based Superconductors

Frequency multiplication with toroidal mode number of kink/fishbone modes on a static HL-2A-like tokamak

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arXiv 2022年

作者： Zou, Zhihui Zhu, Ping Kim, Charlson C. Deng, Wei Wang, Xianqu Hou, Yawei CAS Key Laboratory of Geospace Environment Department of Plasma Physics and Fusion Engineering University of Science and Technology of China Hefei230026 China International Joint Research Laboratory of Magnetic Confinement Fusion and Plasma Physics State Key Laboratory of Advanced Electromagnetic Engineering and Technology School of Electrical and Electronic Engineering Huazhong University of Science and Technology Wuhan430074 China Department of Engineering Physics University of Wisconsin-Madison MadisonWI53706 United States SLS2 Consulting San DiegoCA92107 United States Southwestern Institute of Physics PO Box 432 Chengdu610041 China Institute of Fusion Science School of Physical Science and Technology Southwest Jiaotong University Chengdu610031 China

In the presence of energetic particles (EPs), the Long-Lived Mode (LLM) frequency multiplication with n = 1, 2, 3 or higher is often observed on HL-2A, where n is the toroidal mode number. Hybrid kinetic-MHD model simulations of the energetic particle (EP) driven kink/fishbone modes on a static HL-2A-like tokamak using NIMROD code find that, when the background plasma pressure is relatively high, and the EP pressure and the beam energy are relatively low, the mode frequency increases almost linearly with EP pressure, and the frequency is proportional to n ("frequency multiplication"), even in absence of any equilibrium plasma rotation. In addition, the frequency multiplication persists as the safety factor at magnetic axis q0 varies. In absence of EPs, the growth rate of the 1/1 mode is the largest;however, as the EP pressure increases, the growth rate of 2/2 modes or 3/3 modes becomes dominant, suggesting that the higher-n modes are more vulnerable to EPs. These results may shed light on the understanding about the toroidal mode number dependence of kink/fishbone modes in the advanced scenarios of tokamaks with weak or reversed central magnetic shear. Copyright © 2022, The Authors. All rights reserved.

关键词： Safety factor

Complementary configuration and operation of Wind-Solar-Hydropower-Storage Systems: A comprehensive review

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Complementary configuration and operation of Wind-Solar-Hydr...

IEEE Conference on Energy Internet and Energy System Integration (EI2)

作者： Xinzhi Ding Dayi Li Wei Huang Yiping Chen State Key Laboratory of Advanced Electromagnetic Technology School of Electrical and Electronic Engineering Huazhong University of Science and Technology Wuhan Yunnan Electric Power Test and Research Institute (Group) Co. Kunming Yunnan Power Grid Co. Ltd. Kunming Novel Electric Power System (Beijing) Research Institute of China Southern Power Grid Beijing China

ISBN: (数字)9798331523527

ISBN: (纸本)9798331523534

With a high percentage of renewable energy systems connected to the grid, the intermittent and volatile nature of their output adversely affects the safe and stable operation of the grid. The limited system regulation capability also leads to a reduction of resource utilization. Thus, in order to solve the problems of poor power quality, unstable output and incomplete consumption of new energy sources connected to the grid, it is crucial to carry out the research on the optimal scheduling of power systems based on power generation prediction for wind power, photovoltaic, hydropower and storage systems. Accordingly,multi-objective optimized scheduling based on hybrid energy system configuration has become a highly sought-after solution. This paper firstly summarizes the current renewable energy development issues, then reviews generation forecasting and storage capacity allocation methods for hybrid renewable energy generation systems, analyzes the energy management and control strategies of hybrid energy systems, and finally explores the potential for further large-scale engineering applications of wind-solar-hydropower-storage hybrid systems.

关键词： Reviews Optimal scheduling System integration Wind power generation Hybrid power systems Regulation Resource management Forecasting Energy management Energy storage

PDCapsNet: A Convolution Neural Network Method for COVID-19 Detection from Chest X-Ray Images

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PDCapsNet: A Convolution Neural Network Method for COVID-19 ...

IEEE International Symposium on Information (IT) in Medicine and Education, ITME

作者： Zhihao Liang Huijuan Lu Cunqian You Wenjie Zhu Li Xie Yudong Yao Key Laboratory of Electromagnetic Wave Information Technology and Metrology College of Information Engineering China Jiliang University Hangzhou Zhejiang Province China College of Information Engineering China Jiliang University Drore Information and Technology Co. LTD Hangzhou Zhejiang Province China College of Information Engineering China Jiliang University Modern Educational Technology Center Hangzhou City Zhejiang Province China College of Biomedical Engineering and Instrumentation Science Zhejiang University Institute of Advanced Digital Technologies and Instrumentation Hangzhou Zhejiang Province China Department of Electrical and Computer Engineering Stevens Institute of Technology Hoboken New Jersey USA

The COVID-19 epidemic started in 2019 and it is still important to develop intelligent and efficient diagnostic methods for the detection of COVID-19. In the task of COVID-19 X-ray image recognition, conventional deep neural networks encounter challenges in effectively discerning distinctive features within pneumonia images, resulting in limited generalization capability when confronted with novel samples. To address this issue, we introduce a novel model in this paper, denoted as PDCapsNet. The model effectively exploits Pyconv's multi-scale fusion technique and leverages the capsule network's capacity to encapsulate diverse attributes of specific entities within COVID-19 X-ray images, resulting in enhancements in both accuracy and generalization. Experimental results show that the proposed model outperforms other previous related works.

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Observation of nonreciprocal magneto-optical scattering in nonencapsulated few-layered CrI3

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arXiv 2020年

作者： Guo, Kai Liu, Zhen Hu, Guangwei Shi, Zhongtai Li, Yue Zhang, Linbo Chen, Haiyan Zhang, Li Zhou, Peiheng Lu, Haipeng Lin, Miao-Ling Liu, Sizhao Cheng, Yingchun Liu, Xue Lu Xie, Jianliang Bi, Lei Tan, Ping-Heng Deng, Long jiang Qiu, Cheng-Wei 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 Department of Electrical and Computer Engineering National University of Singapore 117583 Singapore Key Laboratory of Flexible Electronics Institute of Advanced Materials Jiangsu National Synergetic Innovation Center for Advanced Materials Nanjing Tech University Nanjing211816 China State Key Laboratory of Superlattices and Microstructures Institute of Semiconductors Chinese Academy of Sciences P. O. Box 912 Beijing100083 China

"Magneto-optical" effect refers to a rotation of polarization plane, which has been widely studied in traditional ferromagnetic metal and insulator films and scarcely in two-dimensional layered materials. Here we uncover a new nonreciprocal magneto-inelastic light scattering effect in ferromagnetic few-layer CrI3. We observed a rotation of the polarization plane of inelastic light scattering between -20o and +60o that are tunable by an out-of-plane magnetic field from -2.5 to 2.5 T. It is experimentally observed that the degree of polarization can be magnetically manipulated between -20% and 85%. This work raises a new magneto-optical phenomenon and could create opportunities of applying 2D ferromagnetic materials in Raman lasing, topological photonics, and magneto-optical modulator for information transport and storage. © 2020, CC BY-NC-SA.

关键词： Ferromagnetic materials