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Implication of Climate Change Induced Variation in Wind Extremes on Wind Farm in Mountainous Area of Central China—A Case Study of Hengshan

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Energy Procedia 2014年 61卷 2262-2266页

作者： Sheng Su Guangyuan Liu Na Wang Yinhong Li Xianzhong Duan Hunan key laboratory of smart grids operation & control (Changsha University of Sci.& Tech.) Jinpen Road Changsha 410004 China State Key Lab. of Advanced Electromagnetic Engineering & Tech. (Huazhong University of Sci.& Tech.) Luoyu road Wuhan 430074 China

Wind load is critical to the safety of wind turbines. Wind turbines are designed according to the referrence wind speed of 50-year recurrence interval. The climate change induced variation in extremes of wind could impact safety of wind turbines. Meteorological data from Hengshan weather station in central China is investigated. The wind data of 1973–1992 and 1992–2011 are utilized to estimate the extreme wind of 50-year recurrence interval using method of independent storm and generalized pareto distribution model. It is uncovered that although extreme wind of 50-year recurrence interval escalate a little during the two time spans, it will not affect the safety of wind turbines over there notably.

关键词： Wind turbine recurrence interval extreme wind climate change

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Modeling of TWIP steel tensile behavior with crystal plasticity finite element method

Modeling of TWIP steel tensile behavior with crystal plastic...

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2014 International Conference on Materials Science and Computational engineering, ICMSCE 2014

作者： Wang, Yuan Yuan Sun, Xin Wang, Yan Dong Hu, Xiao Hua Zbib, Hussein M. Key Laboratory for Anisotropy and Texture of Materials Northeastern University Shenyang 110819 China Computational Science and Mathematics Division Pacific Northwest National Laboratory Richland WA 99352 United States State Key Lab. for Advanced Metals Materials and Collaborative Innovation Center of Steel Tech. University of Science and Technology Beijing 100083 China School of Mechanical and Materials Engineering Washington State University Pullman WA 99164 United States

ISBN: (纸本)9783038350996

We developed a plane-strain crystal plasticity finite element (CPFE) numerical model to predict the tensile behavior of twinning-induced plasticity (TWIP) steel with both slip and mechanical twinning as the main deformation modes. Our CPFE model may not only predict well the tensile stress versus strain (S-S) curve but also capture the variation in the volume fraction of twins with a reasonable accuracy. The nucleation of mechanical twin is obviously controlled by the stress concentration. At the same time, the growth of twin may either lead to a stress relaxation in the matrix or cause a local stress concentration around twin, which depends on the deformation condition. © (2014) Trans Tech Publications, Switzerland.

关键词： Finite element method

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Active landmark configuration for accurate nano-positioning

Active landmark configuration for accurate nano-positioning

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6th IFAC Symposium on Mechatronic Systems, MECH 2013

作者： Yuan, Shuai Liu, Lianqing Wang, Zhidong Xi, Ning Wang, Yuechao Dong, Zaili State Key Lab. Robot. SIA. Chinese Academy of Sciences Shenyang 110016 China Shenyang Jianzhu University Shenyang 110168 China Graduate University of the Chinese Academy of Sciences Beijing 100039 China Dept. of Advanced Robotics Chiba Institute of Technology Chiba 275-0016 Japan Dept. of Electrical and Computer Engineering Michigan State University United States

ISBN: (纸本)9783902823311

The spatial uncertainties of atom force microscopy (AFM) tip position hinder the AFM based nano-manipulation. Although the landmark based tip localization can be applied to improve the tip position accuracy in the task space, the PZT nonlinearity and system drift are still a challenge to compensation performance when the tip is positioned far from the landmark. Therefore this paper proposes an active landmark configuration. This method first estimates the nearby area called as the landmark domain around the target position, and then actively manipulates the landmark into the landmark domain by using virtual hand to improve the positioning accuracy. Simulation and experiment illustrate the validity of the proposed method. © 2013 IFAC.

关键词： Nanotechnology

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Measuring Near-Field Radiative Heat Transfer in a Graphene-SiC Heterostructure

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Physical Review Applied 2023年第2期19卷 024019-024019页

作者： Naeem Iqbal Sen Zhang Shuai Wang Zezheng Fang Yaoyuan Hu Yongdi Dang Minjie Zhang Yi Jin Jianbin Xu Binfeng Ju Yungui Ma State Key Lab of Modern Optical Instrumentation Centre for Optical and Electromagnetic Research College of Optical Science and Engineering International Research Center for Advanced Photonics Zhejiang University Hangzhou China The State Key Lab of Fluid Power Transmission and Control School of Mechanical Engineering Zhejiang University Hangzhou China Zhejiang Province Key Laboratory of Quantum Technology and Device Department of Physics Zhejiang University Hangzhou China Department of Electrical and Electronic Engineering The University of Hong Kong Pokfulam Road Hong Kong China

Near-field radiative heat transfer between closely placed objects may exceed the far-field black-body radiation limit by orders of magnitude, especially between polaritonic materials. Great efforts have been made to experimentally measure this fundamental effect in various systems. In this work, we manage to experimentally characterize the near-field thermal emission between less explored plasmon-phonon hybrid material systems made of a graphene-SiC heterostructure. The experiment is carried out using a custom-designed all-optical measurement setup. A heat flux enhancement factor of 26 over the black-body radiation limit is obtained at a 150-nm vacuum gap. Three fundamental modes, i.e., surface plasmon and phonon polaritons with frustrated modes, are identified to contribute the near-field heat flux in this hybrid system. The measured results are well reproduced from the analytical calculations, indicating the robustness of the measurement. Deeper experimental explorations for near-field heat transfer between more complicated material systems could be encouraged in the future.

关键词： Energy harvesting devices Heat transfer Near-field optics Surface plasmon polariton Graphene Van der Waals systems Optical techniques

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Reduced-Order Model-Based Low-Frequency Mode Damping Analysis for Grid-Integrated Wind Farm Via Vsc-Hvdc System

SSRN

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SSRN 2023年

作者： Li, Qiutong Wang, Yukun Mu, Qing Sun, Haishun Li, Yutong Xiong, Xinyao State Key Lab of Advanced Electromagnetic Engineering and Technology School of Electrical and Electronic Engineering Huazhong University of Science and Technology Wuhan430074 China Central China Branch State Grid Corporation of China Wuhan430070 China China Electric Power Research Institute Beijing100192 China

The offshore subsystem of grid-integrated wind farm via VSC-HVDC (Voltage Source Converter-High Voltage Direct Current) consists of direct-drive type wind turbine generators (WTGs) and sending end converter (SEC) of VSC-HVDC. The SEC regulates AC voltage using voltage/frequency (V/F) control, while the grid-side converters (GSC) of WTGs synchronize to the AC voltage by a phase-locked loop (PLL). Eigenvalue analysis reveals that there exists a pair of low-frequency modes within the offshore subsystem which might be unstable at high level power output of WTGs. Participation factors and eigenvalue sensitivity analysis demonstrate that the low-frequency mode is closely related to the V/F control of SEC and PLL of GSC. According to this knowledge, a reduced-order s-domain model is derived from the full-order state-space model of the offshore subsystem with PLL dynamics of WTGs reserved. The damping of PLL dynamics is then investigated and divided into two parts, i.e., the intrinsic damping of PLL control and additional damping introduced by V/F control of the SEC. Consequently, a damping calculation method is developed. It is found that the damping calculation based on the reduced-order model represents the stability of the low-frequency mode exactly, implying that this reduced-order model reserved the mode dynamics mentioned above. The impact of different PLL and V/F control parameters on the damping characteristics is further studied. Time-domain simulations validate the effectiveness of the proposed damping analysis method, which could be helpful for control design to avoid the risk of low-frequency oscillation in the offshore system of grid-integrated wind farms via VSC-HVDC. © 2023, The Authors. All rights reserved.

关键词： Offshore wind farms

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First-Principles Study on the Cu-Cr Interfaces in Vacuum Circuit Breaker Contacts

SSRN

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SSRN 2023年

作者： Gui, Xianxian Wu, Chuanqi Yuan, Zhao Liu, Liming Wang, Cao Chen, Lixue Liu, Xueliang Ye, Jingjing Liu, Shan State Key Laboratory of Advanced Electromagnetic Engineering and Technology School of Electrical and Electronic Engineering Huazhong University of Science and Technology Hubei Wuhan430074 China Key Lab Pulsed Power Technol Minist Educ School of Electrical and Electronic Engineering Hubei Wuhan430074 China State Grid Hubei Electric Power Research Institute Hubei Wuhan430077 China

Based on the experimental phenomenon that the breakdown position of the CuCr contact head in a vacuum circuit breaker may be the Cu-Cr phase boundary, the Cu-Cr interfacial binding models have been developed. The work function, density of states, work of interfacial separation, interfacial energy, charge transfer, band energy, and charge density distribution of Cu, Cr and Cu-Cr phase boundaries are calculated from the first principles. The internal properties of CuCr contact breakdown have been analyzed from the microscopic atomistic point of view. The CuCr interface junction was found to have a smaller work function than pure copper and pure chromium. The reduced work function is prone to field emission, thus increasing the possibility of electrical breakdown. Three interfacial binding models Cu(110)/Cr(110), Cu(111)/Cr(111) and Cu(110)/Cr(100) are established in this paper. By comparing the separation work and interfacial energy, it is found that Cu(111)/Cr(111) is relatively stable. In this paper, we provide a theoretical basis for increasing the voltage strength of vacuum circuit breakers. © 2023, The Authors. All rights reserved.

关键词： Timing circuits

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Track-before-detect of weak ballistic target using elliptical hough transform

Track-before-detect of weak ballistic target using elliptica...

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IET International Radar Conference 2013

作者： Rao, Bin Zong, Zhi-Wei Nie, Yuanping State Key Lab. of Complex Electromagnetic Environ. Effects on Electron. and Info. Syst. Changsha 410073 China College of Electronic Science and Engineering National University of Defense Technology Changsha 410073 China

ISBN: (纸本)9781849196031

A track-before-detect (TBD) algorithm based on elliptical Hough transform (EHT) is presented for jointly detecting and tracking weak ballistic targets during its exoatmospheric flight. The new method makes use of the fact that the ballistic target follows the elliptical orbit when restricted to two-body problem. The relationship between raw radar measurements in the data space and the elliptical parameters in the parameter space is established with coordinate transformations. The EHT detection algorithm is designed and the orbit planarity is also considered to reduce the noise accumulation effect. The detection performances related to primary and second thresholds and signal-to-noise ratio (SNR) are analyzed and verified through simulations. The advantage of the new method lies in it can not only detect and track weak ballistic targets but also can predict the impact point by using availab.e parameters.

关键词： Hough transforms

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Electrochemical Mechanism of Blood-Compatibility of TiO2-x Film for Surface Modification of Cardiovascular Bio-medical Devices

Electrochemical Mechanism of Blood-Compatibility of TiO2-x F...

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The 60th Annual Meeting of The International Society of Electrochemistry(第60届国际电化学会议)

作者： G.J.Wan N.Huang J.Zh.Zhou P.Yang Y.X.Leng H.Sun X.Wu Zh.H.Lin State Key Lab. of Physical Chemistry of the Solid Surface College of Chem. & Chem. Engin.Xiamen UniversityXiamen 361005China Key Lab. of Advanced Technology for Materials of Education Ministry of ChinaCollege of Materials Science and EngineeringSouthwest Jiaotong UniversityChengdu610031China State Key Lab. of Physical Chemistry of the Solid SurfaceCollege of Chem. & Chem. Engin.Xiamen UniversityXiamen 361005China Key Lab. of Advanced Technology for Materials of Education Ministry of China College of Materials Science and EngineeringSouthwest Jiaotong UniversityChengdu610031China

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Experimental research on the characteristics of steam-water counter-current flow in the Pressurizer Surge Line assembly

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Experimental Thermal and Fluid Science 2018年 96卷 180-191页

作者： Jiangtao Yu Dalin Zhang Leitai Shi Zhiwei Wang Wenxi Tian G.H. Su S.Z. Qiu State Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong University 28 Xianning West Road Xi’an 710049 China Shaanxi Key Lab. of Advanced Nuclear Energy and Technology School of Nuclear Science and Technology Xi’an Jiaotong University 28 Xianning West Road Xi’an 710049 China

To investigate Counter-Current Flow (CCF) characteristics in the Pressurizer Surge Line (PZR SL) assembly of the large advanced passive nuclear reactors, steam-water CCF experiments are carried out on a stainless steel test section, which is a 1:4 scaled-down model of the AP1000 PZR SL assembly. The inner diameter of the test PZR SL pipe is 90 mm, which also belongs to the large-diameter pipes, as same as the prototype PZR SL pipe, in the field of Counter-Current Flow Limitation (CCFL) researches. The present steam-water CCFL experiments are conducted under normal pressure and saturated temperature, with the PZR simulator collapse water level ranging from 350 to 900 mm. CCFL becomes severer at higher steam flow rate, and the most limiting CCFL effect locates between the PZR simulator bottom head and the vertical part of PZR SL pipe. The onset of CCFL and zero liquid penetration (ZP) are two critical conditions in the CCF development process, dividing the process into three stages: Before-CCFL, Partial-CCFL, and CCFL-ZP. According to the local CCFL conditions, the development of the CCFL process is also divided into four-regions since onset of CCFL. The present steam-water CCF data are well normalized in terms of dimensionless Kutateladze (Ku) numbers, and a Ku-type empirical partial CCFL correlation is developed. The comparisons of the present CCF data and partial CCFL correlation with the CCF data and correlations of former experiment researches validate that the present empirical partial CCFL correlation is conservative to predict steam-water partial CCFL in the prototype PZR SL assembly of the large advanced passive nuclear reactors.

关键词： Steam-water counter-current flow Partial CCFL correlation Pressurizer surge line assembly advanced passive nuclear reactors ADS Automatic Depressurization System ADS1-3 First to Third Stages of ADS ADS4 Fourth Stage of ADS CCF Counter-Current Flow CCFL Counter-Current Flow Limitation CCFL-1 The 1st grade of CCFL region CCFL-2 The 2nd grade of CCFL region CCFL-3 The 3rd grade of CCFL region CCFL-L Local CCFL at the T-junction of HL pipe and PZR SL pipe CCFL-S Local CCFL along the PZR SL pipe CCFL-U Local CCFL at the location between the PZR simulator bottom head and vertical part of PZR SL pipe CCFL-ZP Zero liquid penetration region or stage CMT Core Makeup Tank COCF Co-Current Flow HL Hot Leg IRWST In-containment Refueling Water Storage Tank Ku Kutateladze PRHR Passive Containment Cooling System PWRs Pressurized Water Reactors PZR SL Pressurizer Surge Line RC Reactor Core RCS Reactor Coolant System RPV Reactor Pressure Vessel SBLOCAs Small-Break Loss-of-Coolant Accidents ZP zero liquid penetration

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Sacos-Plate: A New Thermal-Hydraulic Subchannel Analysis Code for Plate Type Fuel Assemblies

SSRN

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SSRN 2023年

作者： Sun, Ruiyu Wang, Jianjun Wang, Jinshun Chen, Ronghua Jiang, Xing Tian, Wenxi Qiu, Suizheng Su, Guanghui Gui, Minyang Harbin Engineering University China School of Nuclear Science and Technology Xi’an Jiaotong University Shaanxi Xi’an710049 China Shaanxi Key Lab. of Advanced Nuclear Energy and Technology Xi’an Jiaotong University China State Key Lab. of Multiphase Flow in Power Engineering Xi’an Jiaotong University China Shanghai Nuclear Engineering Research Design Institute Shanghai China

Over the past few decades, plate-type fuel elements have been widely used in advanced research reactors, small modular pressurized water reactors, production reactors, etc., with the advantages of compact structure arrangement, good heat transfer characteristics and high fuel consumption. Currently, a thermal-hydraulic subchannel analysis code, namely SACOS-PLATE code, was newly designed to satisfy the calculation of different types of plate fuel elements under various steady-state operating conditions. Based on the original SACOS code, this updated version modifies the flow distribution model, the plate heat conduction model, the heat distribution model as well as the flow heat transfer model, and then realizes the simulation of the special thermal-hydraulic phenomena of the fuel and the rectangular flow channel. In this present study, the RA-6 experimental data was used to validate the code, and the simulation calculation was performed on the JRR-3 research reactor, which proved the good computing capability of SACOS-PLATE code. © 2023, The Authors. All rights reserved.

关键词： Plates (structural components)

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