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Mechanical Response of Conductor on Round Core(CORC)Cables Under Electromagnetic Force

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Acta Mechanica Solida Sinica 2023年第3期36卷 418-427页

作者： junfeng wu Donghui Liu Xingyi Zhang Huadong Yong Key Laboratory of Mechanics on Disaster and Environment in Western China Ministry of Education of ChinaLanzhou UniversityLanzhou 730000China Department of Mechanics and Engineering Sciences College of Civil Engineering and MechanicsLanzhou UniversityLanzhou 730000China

The conductor on round core(CORC)cables are fabricated with multilayer high-temperature superconductor tapes,which are helically wound around a circular central *** large Lorentz force will be generated by the transport current in CORC cables under high magnetic field,which will affect the stress and strain distributions of tapes in the cables and the performance of superconducting *** paper establishes a two-dimensional axisymmetric model to analyze the mechanical response of CORC cables subjected to the Lorentz force and analyzes the influence of air gaps on stress and strain distributions inside the *** T-A method is used to calculate the distributions of current density,magnetic field and the Lorentz force in CORC *** mechanical response of CORC cables is analyzed by applying the Lorentz force as an external load in the mechanical *** direction of electromagnetic force is analyzed in CORC cables with and without shielding current,and the results show that the shielding current can lead to the concentration of electromagnetic *** maximum stress and strain occur on both sides of the superconducting tapes in the cables with shielding *** the size of air gaps can reduce the stress and strain in the superconducting *** analysis of mechanical response of CORC cables can play an important role in optimizing the design of CORC cables and improving transmission performance.

关键词： CORC cables Electromagnetic force Mechanical response Air gaps

Numerical study on the laser ablative Rayleigh-Taylor instability

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Acta Mechanica Sinica 2020年第4期36卷 789-796页

作者： Zhiyuan Li Lifeng Wang junfeng wu Wenhua Ye Institute of Applied Physics and Computational Mathematics Beijing 100094China Center for Applied Physics and Technology HEDPSand College of EngineeringPeking UniversityBeijing 100871China

The laser ablative Rayleigh-Taylor instability plays an important role in the ignition of inertial refinement *** accurate simulation of this process is important to control the growth of flow instability during the *** this paper,taking the simulations of the hydrodynamics,the laser energy deposition and the electronic thermal conductivity into consideration,a massively parallel laser ablative Rayleigh-Taylor instability code based on Euler method is *** open source codes are used to improve the code development *** accuracy of the hydrodynamics simulation is tested by an analytical theory about the weakly nonlinear Rayleigh-Taylor instability with double *** benchmark of an one dimensional heat conductivity is used to test the accuracy of the thermal conductivity *** laser ablative plane target and the laser ablative Rayleigh-Taylor instability are used to test the reliability of the code on the simulation of the whole laser ablative *** is shown that the confidence of our numerical simulation code is high and the code framework we designed is *** can be a basis on studying the problems about the laser ablative instability in inertial refinement fusion.

关键词： Laser ablation Inertial confinement fusion Numerical simulation Rayleigh-Taylor instability

Grafting polymeric sulfur onto carbon nanotubes as highly-active cathode for lithium–sulfur batteries

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Journal of Energy Chemistry 2020年第3期29卷 27-33页

作者： junfeng wu Siyu Ding Shihai Ye Chao Lai Institute of New Energy Material Chemistry School of Materials Science and EngineeringNational Institute for Advanced MaterialsNankai UniversityTianjin 300350China School of Chemistry and Materials Science Jiangsu Normal UniversityXuzhou 221116JiangsuChina

Lithium–sulfur(Li–S)batteries are being explored as promising advanced energy storage systems due to their ultra-high energy ***,fast capacity fading and low coulombic efficiency,resulting from the dissolution of polysulfides,remain a serious *** to weak physical adsorptions or barriers,chemical confinement based on strong chemical interaction is a more effective approach to address the shuttle ***,we devise a novel polymeric sulfur/carbon nanotube composite for Li–S battery,for which 2,5-dithiobiurea is chosen as the stabilizer of long-chain *** offers chemical bonds which bridge the polymeric sulfur and carbon *** obtained composite can deliver an ultra-high reversible capacity of 1076.2 m Ahg^-1(based on the entire composite)at the rate of 0.1 C with an exceptional initial Coulombic efficiency of 96.2%,as well as remarkable cycle *** performance is mainly attributed to the reaction reversibility of the obtained polymeric sulfur-based composite during the discharge/charge *** was confirmed by density functional theory calculations for the first time.

关键词： Lithium–sulfur batteries Polymeric sulfur Carbon nanotubes DFT calculations High capacity

ROBUST CONTROL OF GAS TUNGSTEN ARC WELDING SYSTEM

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Chinese Journal of Mechanical Engineering 2007年第5期20卷 32-36页

作者： wu junfeng CHEN Shanben ZHANG Mingjun Department of Automation Harbin University of Science and Technoiogy Harbin 150080. China Institute of Mechanics and Electricity Harbin University of Engineering Harbin 150010 China Welding Institute Shanghai Jiaotong University Shanghai 200030 China nstitute of Mechanics and EIectrcity Harbin University of Engineering Harbin 150010. China

The robust control law for gas tungsten arc welding dynamic process, which is a typical sampled-data system and full of uncertainties, is presented. By using the Lyapunov, second method, the robust control and robust optimal control for a class of sampled-data systems whose underlying continuous-time systems are subjected to structured uncertainties are discussed in time-domain. As a result, some sufficient conditions of robust stability and the corresponding robust control laws are derived. All these results are designed by solving a class of linear matrix inequalities （LMIs） and a class of dynamic optimization problem with LMIs constraints respectively. An example adapted under some experimental conditions in the dynamic process of gas tungsten arc welding system in which the controlled variable is the backside width of weld pool and controlling variable pulse duty ratio, is worked out to illustrate the proposed results, it is shown that the sampling period is the crucial design oarameter.

关键词： Sampled-data system Robust control Linear matrix inequalities (LMIs) Weld pool Pulse duty ratio

基于高光谱成像的复合绝缘子表面污秽成分识别方法

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浙江电力 2025年第1期44卷 124-132页

作者：缪金秦军陈峻宇吴俊锋任明刘润宇国网江苏省电力有限公司无锡供电分公司江苏无锡214000 西安交通大学电力设备电气绝缘国家重点实验室西安710049

复合绝缘子表面的积污成分是影响污秽闪络电压的重要因素。为了探索更为高效且实用化的典型污秽成分识别方法,提出了一种基于高光谱成像的污秽成分识别方法。首先,通过标准人工染污方式制备了7种典型污秽成分的单一或混合积污硅橡胶样品... 详细信息

复合绝缘子表面的积污成分是影响污秽闪络电压的重要因素。为了探索更为高效且实用化的典型污秽成分识别方法,提出了一种基于高光谱成像的污秽成分识别方法。首先,通过标准人工染污方式制备了7种典型污秽成分的单一或混合积污硅橡胶样品,并在模拟日光条件下获得这些积污样品的高光谱二维像元数据。接着,通过在二维像元维度引入KPCA(核主成分分析),有效提取典型污秽成分的像元数据特征,并在光谱维度上基于包络线消除和KPCA建立三维特征子空间。最后,引入KSVM(核支持向量机)算法实现了对7种污秽成分像元的识别。结果表明,该方法对硅橡胶表面积污成分的识别准确率达到了93.75%,而对于混合污秽成分的识别准确率高于80%。研究成果为复合绝缘子污秽成分的现场快速分析和闪络特性评估提供了一种新手段,同时也为带电巡线和实验室污秽度测定提供了参考。

关键词：绝缘硅橡胶绝缘积污反射光谱图像污秽度光谱特征提取

Removal of benzotriazole by heterogeneous photoelectro-Fenton like process using ZnFe_2O_4 nanoparticles as catalyst

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Journal of Environmental Sciences 2013年第4期25卷 801-807页

作者： junfeng wu Wenhong Pu Changzhu Yang Man Zhang Jingdong Zhang School of Environmental Science and Engineering Huazhong University of Science and Technology School of Environmental and Municipal Engineering Henan University of Urban Construction School of Chemistry and Chemical Engineering Huazhong University of Science and Technology

ZnFe2O4 nanoparticles （ZFNPs） were developed as catalyst for the degradation of benzotriazole （BTA） by heterogeneous photoelectro- Fenton （PE-Fenton） like process. ZFNPs were prepared by a co-precipitation process and then characterized with transmission electron microscopy （TEM）, X-ray fluorescence （XRF）, X-ray diffraction （XRD） and BET surface area. Using such ZFNPs as catalyst, the degradation of BTA was investigated. Due to the high catalytic activity of ZFNPs, PE-Fenton like process showed efficient degradation of BTA. The influencing factors such as pH, dosage of ZFNPs, applied potential and initial concentration of BTA were systematically investigated. Under the optimum conditions, 91.2% of BTA was removed after 180 rain treatment.

关键词： ZnFe2O4 nanoparticles photoelectro-Fenton like process benzotriazole heterogeneous catalytic degradation

Novel high voltage RESURF Al GaN/GaN HEMT with charged buffer layer

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Science China(Information Sciences) 2016年第4期59卷 142-151页

作者： Jiayun XIONG Chao YANG Jie WEI junfeng wu Bo ZHANG Xiaorong LUO State Key Laboratory of Electronic Thin Films and Integrated Devices University of Electronic Science and Technology of China

A novel reduced surface field （RESURF） Al GaN /GaN high electron mobility transistor（HEMT）with charged buffer layer is proposed. Its breakdown mechanism and on-state characteristics are *** HEMT features buried Fluorine ions in the GaN buffer layer both under the Drift and the Gate region （FDG）. The section of FDG under the drift region （FD） not only reduces the electric field （E-field） peak at the gate edge but also enhances the E-field in the drift region by the assisted depletion, leading to a significant improvement in breakdown voltage （BV）. Moreover, the section of FDG under the gate （FG） enhances the back barrier and effectively prevents electron injecting from the source to form leakage current, thus a higher BV is achieved. The BV of the proposed HEMT sharply increases to 750 V from 230 V of conventional AlGaN /GaN HEMT with the same dimensional parameters, and the specific on-resistance （Ron,sp） just increases to1.21 m?·cm2from 1.01 m?·cm2.

关键词： high voltage power device AlGaN/GaN HEMT charged buffer RESURF

Finite-time consensus protocols for multi-dimensional multi-agent systems

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Control Theory and Technology 2020年第4期18卷 419-430页

作者： Jieqiang Wei Bart Besselink junfeng wu Henrik Sandberg Karl H.Johansson Ericsson Global AI Accelerator Torshamnsgatan 21StockholmSweden Bernoulli Institute for Mathematics Computer Science and Artificial IntelligenceUniversity of GroningenP.O.Box 4079700 GroningenAKThe Netherlands College of Control Science and Engineering Zhejiang University310027 HangzhouChina Division of Decision and Control Systems KTH Royal Institute of Technology10044 StockholmSweden

A fnite.-time consensus protocol is proposed for multi -dimensional multi- agent systems, using direction peserving signumcontrols. Flipp solutions and nonsmooh analysis tehniques are adopted to handle discontinuities. Suficient and ncessaryconditions are provided to guarantee infinte time convergence and boundedness of the solutions. It turns out that the numberof agents which have cotinuous contol law plays an ssenan role in fnite-tine conerence In adidio it is shown thatthe unit bals itoduced bylp, norms. where p ∈[1,∞] , are inariat for the closed lop.

关键词： Multi-agent systems Network consensus Finite time convergence Nonsmooth analysis

Friction and Wear Behavior of Resin/Graphite Composite under Dry Sliding

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Journal of Materials Science & Technology 2015年第3期31卷 325-330页

作者： Zhenguo Zhu Shuo Bai junfeng wu Li Xu Ting Li Yong Ren Chang Liu Shenyang National Laboratory for Materials Science Institute of Metal Research Chinese Academy of Sciences

The friction and wear behavior of resin/graphite composite has been investigated using a pin-on-disc configuration under dry sliding condition. The results showed that the resin/graphite composite exhibited much better mechanical and tribological properties compared with the unimpregnated graphite. The friction coefficient was reduced by addition of furan resin, which could also prevent the'dusting' wear at loads more than 15 MPa. The steady and lubricated transfer film was easily formed on the counterpart surface due to the interaction of furan resin and wear debris of graphite, which was useful to reduce the wear rate of the resin/graphite composite. The composite is highly promising for mechanical sealing application and can be used at high load for long time sliding.

关键词： Resin/graphite composite Friction and wear 'Dustin