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作者： Zhu, Donghai Zou, Xudong Deng, Lu Huang, Qingjun Zhou, Shiying Kang, Yong StateKey Laboratory of Advanced Electromagnetic Engineering and Technology School of Electrical and Electronic Engineering Huazhong University of Science and Technology Wuhan430074 China Wuhan NARI Limited Liability Company of State Grid Electric Power Research Institute Wuhan430074 China State Key Lab. of Disaster Prev. and Reduction for Pwr. Grid Transmission and Distribution Equipment Changsha410129 China

For doubly fed induction generator (DFIG)-based wind turbines, the rotor side of DFIG is prone to suffering from overcurrent during grid faults, due to large electromotive force (EMF) induced in the rotor circuit. To solve this problem, this paper proposes an inductance-emulating control strategy for DFIG-based wind turbine to suppress the postfault rotor current, thereby enhancing its low-voltage ride through capability. Under the proposed control strategy, once the grid fault is detected, the rotor side converter (RSC) is controlled to emulate an inductance. Furthermore, with proper inductance value, both the required rotor voltage and postfault rotor current can be reduced within the permissible ranges of RSC, thus the controllability of control system can be maintained during transient process. Moreover, the oscillation of electromagnetic torque can be effectively suppressed during transient state of both grid fault and fault recovery. Finally, the simulation and experimental results are presented to demonstrate the effectiveness of the proposed method. © 1986-2012 IEEE.

关键词： Wind turbines

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UB-CQA: A User Attribute Based Community Question Answering System 12

UB-CQA: A User Attribute Based Community Question Answering ...

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12th International Conference on Intelligent Systems and Knowledge engineering (IEEE ISKE)

作者： Zhu, Ziye Liu, Xiaoqian Li, Huakang Li, Tao Nanjing Univ Posts & Telecommun Sch Comp Sci Nanjing 210023 Jiangsu Peoples R China Jiangsu Key Lab Big Data Secur & Intelligent Proc Nanjing 210023 Jiangsu Peoples R China Nanjing Univ Sci & Technol Sch Comp Sci & Engn Nanjing Jiangsu Peoples R China

ISBN: (纸本)9781538618295

Intelligent Community Question Answering (CQA) system is a popular research topic in Natural Language Processing (NLP) area. Recently, the development of distributed data mining has significantly improved the efficiency of the searching and sorting operations in CQA database. However, problems are left unanswered such as how to choose the best answer among multiple candidates for a single question. To solve this issue, we design a CQA system called UB-CQA. First, in database refinement part, we construct an optimized and structured database by the best answer choosing method leveraging user attribute provided by the response provider. Second, in human-computer part, the UB-CQA is able to search and provide a more satisfying answer to users by similarity calculation and re-ranking method leveraging text categorization information. Empirical evaluations show that the best answer choosing and the candidate question re-ranking methods bring great improvements in accuracy and reliability.

关键词： community question answering system user attribute quality prediction text feature extraction text categorization

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High Power Cascaded Erbium Doped Fluoride Fiber Laser at Room Temperature

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IEEE PHOTONICS technology LETTERS 2016年第6期28卷 673-676页

作者： Li, Jianfeng Wang, Lele Luo, Hongyu Xie, Jitao Liu, Yong Univ Elect Sci & Technol China Sch Optoelect Informat State Key Lab Elect Thin Films & Integrated Devic Chengdu 610054 Peoples R China

We demonstrate a high power diode-cladding-pumped cascaded erbium doped fluoride fiber laser at room temperature with I-4(11/2). I-4(13/2) transition at similar to 2.8 mu m and I-4(13/2). I-4(15/2) transition at similar to 1.6 mu m. By simultaneously theoretically optimizing erbium ions dopant concentration and fiber length, maximum output power of 15.2 W centered at 2.885 mu m at a slope efficiency of 26.7% was achieved experimentally after the onset of cascaded transition centered at 1.613 mu m. Maximum output power and slope efficiency of 1.613 mu m cascaded laser were 3.2 W and 7.1%, respectively. In our case, no cooling designs were employed on the fiber owing to the use of lowly erbium doped fiber and cascaded laser cavity that weakened the cascaded multiphonon relaxation processes while improving the optical-to-optical conversion efficiency. To the best of our knowledge, this is the first 10-W level fiber laser at 3-mu m waveband without any special active or passive cooling designs.

关键词： Mid-infrared fiber laser cascaded fiber laser fluoride fiber high power

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Effect of nano-Al addition on properties and microstructure of low-Ag content Sn-1Ag-0.5Cu solders

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JOURNAL OF MATERIALS SCIENCE-MATERIALS IN ELECTRONICS 2016年第7期27卷 7665-7673页

作者： Sun, Lei Zhang, Liang Xu, Le Zhong, Su-Juan Ma, Jia Bao, Li Jiangsu Normal Univ Sch Mech & Elect Engn Xuzhou 221116 Peoples R China Inst Engn Mech State Key Lab Adv Brazing Filler Met & Technol Zhengzhou Res Zhengzhou 450001 Peoples R China

In this paper, Al nanoparticles were manually mixed into the Sn-1Ag-0.5Cu solder paste to prepare composite solder. The content of Al nanoparticles ranged from 0 to 0.4 wt% in the solders. The influences of Al nanoparticles on the melting characteristics, wettability, mechanical properties, microstructure and interfacial intermetallic growth of low-Ag Sn-1Ag-0.5Cu solders on copper substrate were investigated. Results show that added Al nanoparticles can not obviously change the melting point of the Sn-1Ag-0.5Cu solder, and improve the wettability and mechanical properties of plain Sn-1Ag-0.5Cu solder. However, excessive addition Al nanoparticles will reduce the wettability and mechanical properties of the solder. There is an optimum amount of Al nanoparticles in Sn-1Ag-0.5Cu solder, which is 0.1 wt%, and Sn-1Ag-0.5Cu-0.1Al nano-composite solder exhibit the best comprehensive properties. Based on the microstructure examination, it is found that adding Al nanoparticles can obviously refine the microstructure of Sn-1Ag-0.5Cu-xAl solder. In addition, the interfacial intermetallic compounds (IMC) layer thickness of the Sn-1Ag-0.5Cu-xAl solders are smaller than that of plain Sn-1Ag-0.5Cu solder, which indicates that Al nanoparticles can effectively suppress IMC formation and growth.

关键词： Nanoparticles

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Influences of nanotwin volume fraction on the ballistic performance of coarse-grained metals

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Theoretical & Applied Mechanics Letters 2017年第5期7卷 265-268页

作者： Q.D.Ouyang G.J.Weng A.K.Soh X.Guo School of Mechanical Engineering Tianjin UniversityTianfin 300072China Tianjin Key Laboratory of Nonlinear Dynamics and Control Tianjin 300072China Department of Mechanical and Aerospace Engineering Rutgers UniversityNew BrunswickNJ 08903USA School of Engineering Monash University MalaysiaBandar SunwaySalangorMalaysia

Coarse-grained（CG） metals strengthened by nanotwinned（NT） regions possess high strength and good ductility. As such, they are very suitable for applications in bullet-proof targets. Here, a numerical model based on the conventional theory of strain gradient plasticity and the Johnson–Cook failure criterion is employed to study the influences of volume fraction of NT regions on their ballistic *** results show that in general a relatively small twin spacing（4–10 nm） and a moderate volume fraction（7%–20%） will lead to excellent limit velocity and that the influences of volume fraction on limit displacement change with the category of impact processes.

关键词： Nanotwin Ballistic performance Volume fraction Limit velocity Limit displacement

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Study on Double Resonant Performance of Air-core Spiral Tesla Transformer Applied in Repetitive Pulsed Operation

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IEEE TRANSACTIONS ON DIELECTRICS AND ELECTRICAL INSULATION 2015年第4期22卷 1916-1923页

作者： Lee Li Ma Ning Chen Dehuai Liu Lun Kang Qiang Li Mingjia Cheng Yong Pan Yuan Huazhong Univ Sci & Technol State Key Lab Adv Elect Engn & Technol Sch Elect & Elect Engn Wuhan 430074 Peoples R China China Acad Engn Phys Mianyang 621900 Peoples R China Shanghai Jiao Tong Univ IFSA Collaborat Innovat Ctr Shanghai 200240 Peoples R China

Air-core Tesla transformer combined with semiconductor devices can generate repetitive high-voltage pulses effectively. Air-core Tesla transformer of spiral type is suitable for repetitive operation since its primary voltage is relatively low. Based on the double resonance circuit of air-core Tesla transformer, the expressions of secondary voltage, primary current, and the maximum rise-rate of primary current are deduced. The effects of tuning characteristic on the output voltage and energy efficiency are simulated, and further verified by experiments. An air-core Tesla transformer prototype of spiral type is developed. To achieve repetitive operation, a resonant charging and discharging circuit based on air-core Tesla transformer is designed. The repetitive system based on this prototype can generate microsecond pulses with an average peak voltage of -140 kV at 300 Hz repetition rate. In repetitive mode, the tuning ratio is recommended to range in 1.0-2.0 to achieve high energy efficiency. The output voltage could be higher by increasing the charging voltage or tuning ratio.

关键词： Air-core Tesla transformer resonant charging tuning ratio secondary voltage energy efficiency

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Implementing Dense Optical Flow Computation on a Heterogeneous FPGA SoC in C

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ACM TRANSACTIONS ON ARCHITECTURE AND CODE OPTIMIZATION 2016年第3期13卷 1–25页

作者： Chen, Wenjie Wang, Zhibin Wu, Qin Liang, Jiuzhen Chai, Zhilei East China Normal Univ MoE Engn Res Ctr Software Hardware Codesign Techn Shanghai 200062 Peoples R China Jiangnan Univ Sch Internet Things Engn Wuxi 214122 Peoples R China

High-quality optical flow computation algorithms are computationally intensive. The low computational speed of such algorithms causes difficulties for real-world applications. In this article, we propose an optimized implementation of the classical Combine-Brightness-Gradient (CBG) model on the Xilinx ZYNQ FPGA-SoC, by taking advantage of the inherent algorithmic parallelism and ZYNQ architecture. The execution time decreases to 0.82 second with a lower power consumption (1.881W). It is better than software implementation on PC (Intel i7-3520M, 2.9GHz), which costs 2.635 seconds and 35W. We use C rather than HDLs to describe the algorithm for rapid prototyping.

关键词： Variational optical flow computation FPGA-accelerated heterogeneous SoC ZYNQ high-level synthesis (HLS)

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The Event Horizon Telescope Image of the Quasar NRAO 530

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Astrophysical Journal 2023年第2期943卷 170-170页

作者： Jorstad, Svetlana Wielgus, Maciek Lico, Rocco Issaoun, Sara Broderick, Avery E. Pesce, Dominic W. Liu, Jun Zhao, Guang-Yao Krichbaum, Thomas P. Blackburn, Lindy Chan, Chi-Kwan Janssen, Michael Ramakrishnan, Venkatessh Akiyama, Kazunori Alberdi, Antxon Algaba, Juan Carlos Bouman, Katherine L. Cho, Ilje Fuentes, Antonio Gómez, José L. Gurwell, Mark Johnson, Michael D. Kim, Jae-Young Lu, Ru-Sen Martí-Vidal, Iván Moscibrodzka, Monika Pötzl, Felix M. Traianou, Efthalia van Bemmel, Ilse Alef, Walter Anantua, Richard Asada, Keiichi Azulay, Rebecca Bach, Uwe Baczko, Anne-Kathrin Ball, David Baloković, Mislav Barrett, John Bauböck, Michi Benson, Bradford A. Bintley, Dan Blundell, Raymond Bower, Geoffrey C. Boyce, Hope Bremer, Michael Brinkerink, Christiaan D. Brissenden, Roger Britzen, Silke Broguiere, Dominique Bronzwaer, Thomas Bustamante, Sandra Byun, Do-Young Carlstrom, John E. Ceccobello, Chiara Chael, Andrew Chatterjee, Koushik Chatterjee, Shami Chen, Ming-Tang Chen, Yongjun Cheng, Xiaopeng Christian, Pierre Conroy, Nicholas S. Conway, John E. Cordes, James M. Crawford, Thomas M. Crew, Geoffrey B. Cruz-Osorio, Alejandro Cui, Yuzhu Davelaar, Jordy De Laurentis, Mariafelicia Deane, Roger Dempsey, Jessica Desvignes, Gregory Dexter, Jason Dhruv, Vedant Doeleman, Sheperd S. Dougal, Sean Dzib, Sergio A. Eatough, Ralph P. Emami, Razieh Falcke, Heino Farah, Joseph Fish, Vincent L. Fomalont, Ed Ford, H. Alyson Fraga-Encinas, Raquel Freeman, William T. Friberg, Per Fromm, Christian M. Galison, Peter Gammie, Charles F. García, Roberto Gentaz, Olivier Georgiev, Boris Goddi, Ciriaco Gold, Roman Gómez-Ruiz, Arturo I. Gu, Minfeng Hada, Kazuhiro Haggard, Daryl Haworth, Kari Hecht, Michael H. Hesper, Ronald Heumann, Dirk Ho, Luis C. Ho, Paul Honma, Mareki Huang, Chih-Wei L. Huang, Lei Hughes, David H. Ikeda, Shiro Impellizzeri, C.M. Violette Inoue, Makoto James, David J. Jannuzi, Buell T. Jeter, Britton Jiang, Wu Jiménez-Rosales, Alejandra Joshi, Abhishek V. Jung, Taehyun Karami, Mansour Karuppusamy, Ramesh Kawashima, Tomohisa Keati Institute for Astrophysical Research Boston University 725 Commonwealth Avenue Boston 02215 MA United States Max-Planck-Institut für Radioastronomie Auf dem Hügel 69 Bonn D-53121 Germany Instituto de Astrofísica de Andalucía-CSIC Glorieta de la Astronomía s/n Granada E-18008 Spain INAF-Istituto di Radioastronomia Via P. Gobetti 101 Bologna I-40129 Italy Center for Astrophysics Harvard & Smithsonian 60 Garden Street Cambridge 02138 MA United States NASA Hubble Fellowship Program Perimeter Institute for Theoretical Physics 31 Caroline Street North Waterloo N2L 2Y5 ON Canada Department of Physics and Astronomy University of Waterloo 200 University Avenue West Waterloo N2L 3G1 ON Canada Waterloo Centre for Astrophysics University of Waterloo Waterloo N2L 3G1 ON Canada Harvard University 20 Garden Street Cambridge 02138 MA United States Steward Observatory Department of Astronomy University of Arizona 933 N. Cherry Avenue Tucson 85721 AZ United States Data Science Institute University of Arizona 1230 N. Cherry Avenue Tucson 85721 AZ United States Program in Applied Mathematics University of Arizona 617 N. Santa Rita Tucson 85721 AZ United States Astronomy Department Universidad de Concepción Casilla 160-C Concepción Chile Finnish Centre for Astronomy with ESO University of Turku FI-20014 Finland Aalto University Metsähovi Radio Observatory Metsähovintie 114 Kylmälä FI-02540 Finland Massachusetts Institute of Technology Haystack Observatory 99 Millstone Road Westford 01886 MA United States National Astronomical Observatory of Japan 2-21-1 Osawa Mitaka Tokyo 181-8588 Japan Department of Physics Faculty of Science Universiti Malaya Kuala Lumpur 50603 Malaysia California Institute of Technology 1200 East California Boulevard Pasadena 91125 CA United States Department of Astronomy and Atmospheric Sciences Kyungpook National University Daegu 702-701 South Korea Shanghai Astronomical Observatory Chinese Academy of Sciences 80

We report on the observations of the quasar NRAO 530 with the Event Horizon Telescope (EHT) on 2017 April 5−7, when NRAO 530 was used as a calibrator for the EHT observations of Sagittarius A*. At z = 0.902, this is the most distant object imaged by the EHT so far. We reconstruct the first images of the source at 230 GHz, at an unprecedented angular resolution of ∼20 μas, both in total intensity and in linear polarization (LP). We do not detect source variability, allowing us to represent the whole data set with static images. The images reveal a bright feature located on the southern end of the jet, which we associate with the core. The feature is linearly polarized, with a fractional polarization of ∼5%-8%, and it has a substructure consisting of two components. Their observed brightness temperature suggests that the energy density of the jet is dominated by the magnetic field. The jet extends over 60 μas along a position angle ∼ −28°. It includes two features with orthogonal directions of polarization (electric vector position angle), parallel and perpendicular to the jet axis, consistent with a helical structure of the magnetic field in the jet. The outermost feature has a particularly high degree of LP, suggestive of a nearly uniform magnetic field. Future EHT observations will probe the variability of the jet structure on microarcsecond scales, while simultaneous multiwavelength monitoring will provide insight into the high-energy emission origin. © 2023. The Author(s). Published by the American Astronomical Society.

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Mesoscale electric fluctuations interacting with zonal flows, magnetic fluctuations and turbulence

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NUCLEAR FUSION 2017年第7期57卷

作者： Zhao, K. J. Nagashima, Y. Diamond, P. H. Dong, J. Q. Itoh, K. Itoh, S. -I. Yan, L. W. Cheng, J. Fujisawa, A. Inagaki, S. Kosuga, Y. Sasaki, M. Huang, Z. H. Yu, D. L. Li, Q. Ji, X. Q. Song, X. M. Huang, Y. Liu, Yi Yang, Q. W. Ding, X. T. Duan, X. R. Southwestern Inst Phys POB 432 Chengdu 610041 Peoples R China Kyushu Univ Res Inst Appl Mech Kasuga Koen 6-1 Kasuga Fukuoka 8168580 Japan Univ Calif San Diego Ctr Momentum Transport & Flow Org San Diego CA 92093 USA Zhejiang Univ Inst Fus Theory & Simulat Hangzhou 310027 Zhejiang Peoples R China Natl Inst Fus Sci Toki Gifu 5095292 Japan Chubu Univ Inst Sci & Technol Res Kasugai Aichi 4878501 Japan

New mesoscale electric fluctuations (MSEFs) are identified in the edge plasmas of the HL-2A tokamak using multiple Langmuir probe arrays. The MSEFs, resulting from the synchronization and having components of dominant geodesic acoustic mode (GAM) and m/n = 6/2 potential fluctuations, are found at the same frequency as that of the magnetic fluctuations of m/n = 6/2 (m and n are poloidal and toroidal mode numbers, respectively). The temporal evolutions of the MSEFs and the magnetic fluctuations clearly show the frequency entrainment and the phase lock between the GAM and the m/n = 6/2 magnetic fluctuations. The results indicate that GAMs and magnetic fluctuations can transfer energy through nonlinear synchronization. The nonlinear coupling analyses show that the MSEFs couple to turbulence and low frequency zonal flows (LFZFs). This suggests that the MSEFs may contribute to the LFZF formation, reduction of turbulence level, and thus confinement regime transitions. The analysis of the envelope modulation demonstrates that both the MSEFs and the LFZFs modulate the turbulence while the MSEFs are modulated by the LFZFs.

关键词： magnetic fluctuations turbulence zonal flows mesoscale electric fluctuations nonlinear synchronization

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Implementation and Optimization of AES Algorithm on the Sunway TaihuLight 17

Implementation and Optimization of AES Algorithm on the Sunw...

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17th International Conference on Parallel and Distributed Computing, Applications and Technologies (PDCAT)

作者： Chen, Yuedan Li, Kenli Fei, Xiongwei Quan, Zhe Li, Keqin Hunan Univ Coll Comp Sci & Elect Engn Changsha 410082 Hunan Peoples R China Natl Supercomp Ctr Changsha Changsha 410082 Hunan Peoples R China SUNY Coll New Paltz Dept Comp Sci New Paltz NY 12561 USA

ISBN: (纸本)9781509050819

With the rapid development of information technology, the security of massive amounts of digital data has attracted huge attention in recent years. In this paper, we provide an efficient parallel implementation of the advanced Encryption Standard (AES) algorithm, a widely used symmetrical block encryption algorithm, based on the Sunway TaihuLight. The Sunway TaihuLight is a China's independently developed heterogeneous supercomputer with peak performance over 100 PFlops. We also optimize the parallel implementation of the AES algorithm based on the Sunway TaihuLight to achieve more optimized performance. The optimization of the parallel AES algorithm in a single SW26010 node is provided. Specifically, we expand the scale to 1024 nodes and achieve the throughput of about 63.91 GB/s (511.28 Gbits/s). Our parallel implementation of the AES algorithm has great parallel scalability and the speedup ratio can be very high with the number of nodes increasing.

关键词： advanced Encryption Standard (AES) Parallelism the Sunway TaihuLight Many-core Speedup Through-put Parallel Scalability

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