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Mapping essential urban land use categories in China(EULUC-China):preliminary results for 2018

science Bulletin 2020年第3期65卷 182-187页

作者： Peng Gong Bin Chen Xuecao Li Han Liu Jie Wang Yuqi Bai Jingming Chen Xi Chen Lei Fang Shuailong Feng Yongjiu Feng Yali Gong Hao Gu Huabing Huang Xiaochun Huang Hongzan Jiao Yingdong Kang Guangbin Lei Ainong Li Xiaoting Li Xun Li Yuechen Li Zhilin Li Zhongde Li Chong Liu Chunxia Liu Maochou Liu Shuguang Liu Wanliu Mao Changhong Miao Hao Ni Qisheng Pan Shuhua Qi Zhehao Ren Zhuoran Shan Shaoqing Shen Minjun Shi Yimeng Song Mo Su Hoi Ping Suen Bo Sun Fangdi Sun Jian Sun Lin Sun Wenyao Sun Tian Tian Xiaohua Tong Yihsing Tseng Ying Tu Hong Wang Lan Wang Xi Wan Zongming Wang Tinghai Wu Yaowen Xie Jian Yang Jun Yang Man Yuan Wenze Yue Hongda Zeng Kuo Zhang Neng Zhang Tao Zhang Yu Zhang Feng Zhao Yichen Zheng Qiming Zhou Nicholas Clinton Zhiliang Zhu Bing Xu Ministry of Education Key Laboratory for Earth System Modeling Department of Earth System ScienceTsinghua UniversityBeijing 100084China Tsinghua Urban Institute Tsinghua UniversityBeijing 100084China Center for Healthy Cities Institute for China Sustainable UrbanizationTsinghua UniversityBeijing 100084China Department of Land Air and Water ResourcesUniversity of CaliforniaDavisCA 95616-8627USA Department of Geological and Atmospheric Sciences Iowa State UniversityAmesIA 50011USA State Key Laboratory of Remote Sensing Science Institute of Remote Sensing and Digital EarthChinese Academy of SciencesBeijing 100101China AI for Earth Laboratory Cross-Strait InstituteTsinghua UniversityBeijing 100084China International Institute for Earth System Sciences Nanjing UniversityNanjing 210093China Research Center for Ecology and Environment of Central Asia Chinese Academy of SciencesUrumchi 830011China Key Laboratory of Forest Ecology and Management Institute of Applied EcologyChinese Academy of SciencesShenyang 110016China National Engineering Laboratory for Applied Technology in Forestry&Ecology in South China College of Life Science and TechnologyCentral South University of Forestry and TechnologyChangsha 410004China College of Surveying&Geo-Informatics Tongji UniversityShanghai 200092China Department of Urban Planning College of Architecture and Urban PlanningTongji UniversityShanghai 200092China Beijing Institute of Urban Planning Beijing 100045China Department of Urban Planning School of Urban DesignWuhan UniversityWuhan 430072China College of Earth Sciences Jilin UniversityChangchun 130061China Research Center for Digital Mountain and Remote Sensing Application Institute of Mountain Hazards and EnvironmentChinese Academy of SciencesChengdu 610041China Institute of Remote Sensing and Geographic Information System School of Earth and Space SciencesPeking UniversityBeijing 100871China Department of Urban and Regional Planning School of Geography and PlanningSun Yat-sen Univ

Land use reflects human activities on *** land use is the highest level human alteration on Earth,and it is rapidly changing due to population increase and *** areas have widespread effects on local hydrology,climate,biodiversity,and food production[1,2].However,maps,that contain knowledge on the distribution,pattern and composition of various land use types in urban areas,are limited to city *** mapping standard on data sources,methods,land use classification schemes varies from city to city,due to differences in financial input and skills of mapping *** address various national and global environmental challenges caused by urbanization,it is important to have urban land uses at the national and global scales that are derived from the same or consistent data sources with the same or compatible classification systems and mapping *** is because,only with urban land use maps produced with similar criteria,consistent environmental policies can be made,and action efforts can be compared and assessed for large scale environmental ***,despite of the fact that a number of urban-extent maps exist at global scales[3,4],more detailed urban land use maps do not exist at the same *** at big country or regional levels such as for the United States,China and European Union,consistent land use mapping efforts are rare[5,6](e.g.,https://***/open_land_use/).

关键词： EULUC-China 土地利用类型

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Stability Analysis of Hybrid-Driven Underwater Glider

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China Ocean Engineering 2017年第5期31卷 528-538页

作者： NIU Wen-dong WANG Shu-xin WANG Yan-hui SONG Yang ZHU Ya-qiang Key Laboratory of Mechanism Theory and Equipment Design of Ministry of Education School of Mechanical EngineeringTianjin University The Joint Laboratory of Ocean Observing and Detecting Qingdao National Laboratory for Marine Science and Technology

Hybrid-driven underwater glider is a new type of tmmanned underwater vehicle, which combines the advantages of autonomous underwater vehicles and traditional underwater gliders. The autonomous underwater vehicles have good maneuverability and can travel with a high speed, while the traditional underwater gliders are highlighted by low power consumption, long voyage, long endurance and good stealth characteristics. The hybrid-driven underwater gliders can realize variable motion profiles by their own buoyancy-driven and propeller propulsion systems. Stability of the mechanical system determines the performance of the system. In this paper, the Petrel-II hybrid-driven underwater glider developed by Tianjin University is selected as the research object and the stability of hybrid-driven underwater glider unitedly controlled by buoyancy and propeller has been targeted and evidenced. The dimensionless equations of the hybrid-driven underwater glider are obtained when the propeller is working. Then, the steady speed and steady glide path angle under steady-state motion have also been achieved. The steady-state operating conditions can be calculated when the hybrid-driven underwater glider reaches the desired steady-state motion. And the steady- state operating conditions are relatively conservative at the lower bound of the velocity range compared with the range of the velocity derived from the method of the composite Lyapunov function. By calculating the hydrodynamic coefficients of the Petrel-II hybrid-driven underwater glider, the simulation analysis has been conducted. In addition, the results of the field trials conducted in the South China Sea and the Danjiangkou Reservoir of China have been presented to illustrate the validity of the analysis and *** to show the feasibility of the method of the composite Lyapunov function which verifies the stability of the Petrel-II hybrid-driven underwater glider.

关键词： hybrid-driven underwater glider stability analysis numerical simulation field trials

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design of lossless snubber circuit for phase-shifted full-bridge converter

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Journal of Physics: Conference Series 2020年第2期1650卷

作者： Shengxian Ji Guisheng Jie Shan Gao Hengli Wang Ruitian Wang Xiaohu Liu National key Laboratory of Science and Technology on Vessel Integrated Power System Naval University of Engineering Wuhan 430033 China College of Electrical Engineering Naval University of Engineering Wuhan 430033 China

In the phase-shifted full-bridge circuit, the voltage spike caused by the hard turn-off of the switch tube increases the voltage stress of the switching device. Due to the existence of energy-consuming components such as resistance in the traditional absorption circuit, the efficiency is not always high. Based on the RCD snubber circuit, a low-loss absorption circuit is designed in this paper. This circuit absorbs voltage spikes through an absorption capacitor, and then slowly releases energy through an oscillating circuit consisting of current-limiting inductance, stray inductance, and absorption capacitance. The current-limiting inductance reduces the current stress of the blocking diode effectively, which can be achieved with the absorption not being affected and the power loss being reduced. Finally, the absorption effect and energy loss of the new low-loss absorption circuit and the commonly used RCD circuit were simulated and compared in PSpice software, and verified its feasibility.

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design and application of fiber optical door switch sensor

Design and application of fiber optical door switch sensor

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Optical Fiber Sensors, OFS 2018

作者： Wang, Chaodong Liu, Lihai Tang, Ming China Railway Siyuan Survey and Design Group CO. LTD Wuhan430063 China National Engineering Laboratory for Next Generation Internet Access System School of Optics and Electronic Information Huazhong University of Science and Technology Wuhan430074 China

ISBN: (纸本)9781943580507

关键词： Optical fibers

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Research on Hydrodynamic Interference of a DSRV and a Wrecked Submarine

Research on Hydrodynamic Interference of a DSRV and a Wrecke...

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IEEE International Conference on Underwater system technology: Theory and Applications (USYS)

作者： Hao TAN Duanfeng HAN Lei JU Haitao ZHU Yiran MIAO College of Shipbuilding Engineering Harbin Engineering University Harbin 150000 China Science and Technology on Reactor System Design Technology Laboratory Unclear Power Institute of China Chengdu 610041 China

ISBN: (纸本)9781538694060

In this paper, the viscous flow method based on Computational Fluid Dynamics (CFD) is used to simulate the hydrodynamic interaction of the Deep Submergence Rescue Vehicle (DSRV) involved in the rescue of a wrecked submarine. As the object of study, the drag of the DSRV moving in unbounded flow field is numerically calculated and the calculation results are compared with the experimental values to validate the accuracy of the numerical method. When the DSRV approaches the wrecked submarine in a positive flotation in quasi-static way, the effects of different inflow velocities and the distance between the two objects on the DSRV's drag, lift and pitching moment are simulated and monitored. The results show that when the DSRV is far away from the wrecked submarine, it is subject to the repulsive force from the submarine; when the distance is gradually reduced, the repulsive force is reduced until becoming suction; when the two objects are docking, the DSRV is subjected to the repulsive force from the submarine. This study will provide a reference for the operation of DSRV drivers.

关键词： Underwater vehicles Mathematical model Hydrodynamics Force Numerical models Load modeling Drag

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An investigation of numerical performance enhancement of RELAP5: Numerical stability, higher resolution and an alternative constitutive relation

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Nuclear Engineering and design 2018年 328卷 309-320页

作者： Wei Li Xiaoli Wu Koroush Shirvan Guanghui Su Science Technology on Reactor System Design Technology Laboratory Nuclear Power Institute of China Chengdu 610213 China Massachusetts Institute of Technology 77 Massachusetts Ave Cambridge MA 02139 USA School of Nuclear Science and Technology Xi’an Jiaotong University No. 28 Xianning West Road Xi’an Shanxi 710049 China

The nuclear reactor safety system code RELAP5 decomposes complex flow system of a nuclear reactor into a series of one-dimensional control volumes connected by flow junctions, and solves a set of two-phase two-fluid equations to predict the nuclear reactor system behavior. In spite of its extensive applications, there indeed exist many numerical shortcomings in RELAP5 and it is desirable to constantly improve its numerical performance. In the present work, the numerical performance improvement to RELAP5/MOD3 is carried out from the aspects of numerical stability, high-resolution and alternative constitutive relations. For the enhancement of numerical stability, the virtual mass term is replaced and an interfacial pressure term is added in the phase momentum equations of RELAP5 to make all the characteristic roots real, thus improve the model’s hyperbolicity. In addition, the second-order Minmod TVD flux-limiter scheme replaces the original first-order upwind scheme for advection terms to reduce the numerical diffusion. Furthermore, an alternative interphase friction relation is substituted for the built-in model in RELAP5 to calculate the interphase drag for bubbly/slug flow in the vertical bundle channels. The performance improvement measures work reasonably well, as indicated by the simulation of selected numerical examples and the Bethsy 6.2TC integral effect experiment which corresponds to an intermediate break Pressurized Water reactor Loss of Coolant Accident (PWR LOCA).

关键词： Virtual mass force Interfacial pressure Flux-limiter Interphase friction RELAP5

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Study on Processing Process of SiC Single Crystal Cut with Wire Saw Excited by Ultrasonic

Study on Processing Process of SiC Single Crystal Cut with W...

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International Conference on Mechanical, Control and Computer Engineering (ICMCCE)

作者： Lun Li Shaodong Yang Bofeng Du Shiyu Xu Jishun Li Henan Key Laboratory for Machinery Design and Transmission System Henan University of Science and Technology Luoyang China Zhongqi Changxing (Luoyang) Mechanical and Electrical Equipment Engineering Co. Ltd. Luoyang China Shenzhen Zhaowei Machinery & Electronics Co. Ltd. Shenzhen China

ISBN: (数字)9781728146898

ISBN: (纸本)9781728146904

Owing to high hardness and brittleness, SiC single crystal is the typical difficult-to-machine material. The SiC single crystal workpiece was cut by wire saw excited by transverse ultrasonic, and the cutting process was analyzed in current research. The kinematics equation of ultrasonic excitation wire saw and ordinary wire saw were established, and two different kinematics characteristics were analyzed respectively. The trajectory of abrasive particles in two cutting mode changed fundamentally. The finite element simulation model of single diamond abrasive cutting SiC single crystal was established. The influence of processing parameters on sawing force, surface morphology of SiC single crystal cut with abrasive excited by ultrasonic and ordinary diamond abrasive cutting was analyzed. The results show that sawing force of diamond abrasive excited by ultrasonic is much less than that of ordinary diamond abrasive cutting and the surface morphology is fairly flat. The cutting depth of abrasive has a significant influence on the sawing force and wafer surface.

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Preliminary study on the radiation heat removal capacity in SMR core under high temperature condition

Preliminary study on the radiation heat removal capacity in ...

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2017 International Congress on Advances in Nuclear Power Plants: A New Paradigm in Nuclear Power Safety, ICAPP 2017

作者： Li, Zhongchun Ding, Shuhua Li, Songwei Deng, Jian Nulcear Power Institute of China Chengdu610041 China Science and Technology on Reactor System Design Technology Laboratory Chengdu610041 China

ISBN: (纸本)9784890471676

The advanced fuel design, such as accident tolerant fuel (ATF) was design concept to withstand the high temperatures for extreme condition. When it was equipped in reactor core, the heat removal by radiation would be quite considerable. The radiation heat removal in a simplified SMR core was studied in the present study. The calculation was assumed to be 2D and at steady state. The calculation models were established from fuel assembly to fuel rod. The radiation heat flux was calculated based on the heat balance model when the limitation temperature in the core was reached. The results showed that the radiation heat flux contribute large proportion when the limitation temperature on fuel clad was high. The radiation heat flux was increased with fuel clad temperature limitation value. The higher the emissivity was, the more radiation heat flux removed.

关键词： Temperature

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Transient numerical simulation on the performance of a neon-charged cryogenic loop heat pipe for space applications 69

Transient numerical simulation on the performance of a neon-...

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69th International Astronautical Congress: #InvolvingEveryone, IAC 2018

作者： He, Fa-Long Du, Wang-Fang Zhao, Jian-Fu Chen, Yue-Yong He, Jiang Zhang, Hong-Xing Miao, Jian-Yin National Microgravity Laboratory Institute of Mechanics Chinese Academy of Sciences. Beijing100190 China School of Engineering Science University of the Chinese Academy of Sciences Beijing100049 China Beijing Key Laboratory of Space Thermal Control Technology Beijing100094 China Institute of Spacecraft System Engineering China Academy of Space Technology Beijing100094 China

A transient mathematical model for cryogenic loop heat pipe (CLHP), which possesses high pumping capability and good heat transfer performance that are important for effective and efficient cryogenic heat transport with considerable applications in space and terrestrial surroundings, is established and used to study the performance of a neon-charged CLHP (Ne-CLHP) in the present work. The numerical results are benchmarked with experimental data and a good agreement is achieved. The effects of parasitic heat loss, charged pressure of the working fluid, and heat sink temperature on the performance of the Ne-CLHP are conducted under a constant heat loads applied to the secondary evaporator (1.5 W), which is selected based on the previous experimental study. Based on the numerical results, it is found that the heat sink temperature affects slightly the resistance loss of the system, but markedly the wall temperature of primary evaporator and the maximum heat transport capability. There existed an optimum charged pressure of the working fluid to achieve the maximum heat transport capability. The detailed temperature and pressure characteristics of the Ne-CLHP are also captured which can provide a better understanding of the inherent mechanisms responsible for the phenomena and then provide guidance for the design and optimization of Ne-CLHPs, which can realize efficient cryogenic heat transport in the temperature range of 30-40 K, and promises great application potential in the thermal control of future space infrared exploration system. Copyright © 2018 by Fa-Long He and Jian-Fu Zhao. Published by the IAF, with permission and released to the IAF to publish in all forms. .

关键词： Neon

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A numerical simulation method of co-flow jet airfoil with energy system inside the duct 9th

A numerical simulation method of co-flow jet airfoil with en...

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9th AIAA Flow Control Conference, 2018

作者： Li, Kai Song, Wenping Xu, Jianhua Han, Zhonghua National Key Laboratory of Science and Technology on Aerodynamic Design and Research School of Aeronautics Northwestern Polytechnical University Department of Fluid Mechanics Youyi West Road No. 127 P.O. Box754 Xi’an710072 China

ISBN: (数字)9781624105548

ISBN: (纸本)9781624105548

This paper studies the low speed performance of co-flow jet airfoil with energy system inside the duct. Based on actuator disk theory, the energy system-pump or fan, can be simplified to an ideal actuator disk without thickness, and across the disk the velocity and density of flow are held constant, while the pressure increases. Based on this theory, the two-dimensional flow of the CFJ6415 airfoil is simulated, and a new method for calculating the reaction force is proposed. The simulation employs the validated in-house code, PMNS2D, using Reynolds Averaged Navier-Stokes(RANS) equations with one-equation Spalart-Allmaras turbulence model. Two types of pressure increase distribution across the actuator disk are considered in the numerical simulations. One is uniform and the other is distributed, obtained from a real blade. The numerical simulation results are in good agreement with experimental data, indicating that the numerical simulation method proposed in this paper can well simulate CFJ airfoil with energy system inside the duct. It is of great significance to the design of the inner duct and practical application of co-flow jet technology. © 2018, American Institute of Aeronautics and Astronautics Inc, AIAA. All rights reserved.

关键词： Airfoils

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