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Communications Earth & Environment 2025年第1期6卷 1-13页

作者： Tao Tang Lin Wang Junji Cao Jun Ge Haiyun Shi Xuhui Lee State Key Laboratory of Earth System Numerical Modeling and Application Institute of Atmospheric Physics Chinese Academy of Sciences Beijing China Science Center for Earth System Numerical Simulation Institute of Atmospheric Physics Chinese Academy of Sciences Beijing China CAS Key Laboratory of Regional Climate-Environment for Temperate East Asia Institute of Atmospheric Physics Chinese Academy of Sciences Beijing China Joint International Research Laboratory of Atmospheric and Earth System Sciences School of Atmospheric Sciences Nanjing University Nanjing China School of Environmental Science and Engineering Southern University of Science and Technology Shenzhen China School of the Environment Yale University New Haven CT USA

Drought, a marked deficiency of surface water, has a wide adverse impact on the environment, agriculture, and the socio-economy. The global impact of land use changes on drought features and associated exposures to droughts, however, remains largely unknown. In this study, the changes of drought features are estimated by using the model simulations with and without land use change. We show that historical land use changes since 1850, mainly deforestation and crop expansion, has increased the drought frequency, duration, and severity over half of the global land area. Regions with greater activity tend to experience stronger exacerbation of drought events. Owing to their increasing frequency and prolonged duration, populations, croplands and forests are increasingly exposed to drought events, which poses serious potential impacts on human health, agriculture, and forest ecosystems. The enhanced drought events could be substantially alleviated by potential reforestation activity. Our results provide useful information for land-management-related policy-making.

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Evaluation of Joint Information Environment Service Capability of Space-based Network Information system Based on ANP-Fuzzy Comprehensive Evaluation Method 10

Evaluation of Joint Information Environment Service Capabili...

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10th IEEE Joint International Information Technology and Artificial Intelligence Conference, ITAIC 2022

作者： Han, Chi Jian, Ping Xiong, Wei Fu, Jingyu Aerospace Information Institute Space Engineering University Beijing China Science and Technology on Complex Electronic System Simulation Laboratory Space Engineering University Beijing China

ISBN: (数字)9781665422079

ISBN: (纸本)9781665422079

In the increasingly systematic and networked environment of aerospace equipment, the space-based information service capability is not only affected by the platform and payload capacity of the mission spacecraft, but also increasingly restricted by the network characteristics and network environment for space-based information acquisition. In this context, the joint information environment of the space-based network information system is constructed (JIESNIS). The service capability evaluation index system of JIESNIS is constructed pertinently. Analytic Network Process (ANP) and fuzzy comprehensive evaluation method are combined to evaluate the service capability of JIESNIS. Based on the background of the space-based network information system joint information environment support operation under the customized and active service mode, the simulation model is constructed. The proposed ANP-Fuzzy comprehensive evaluation method is adopted to evaluate the capability JIESNIS, meanwhile the effectiveness of the method is verified. © 2022 IEEE.

关键词： Information services

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Data-driven Operational Effectiveness Evaluation of Space-based Information system 5

Data-driven Operational Effectiveness Evaluation of Space-ba...

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5th IEEE Information Technology, Networking, Electronic and Automation Control Conference, ITNEC 2021

作者： Han, Chi Xiong, Wei Jian, Ping Aerospace Engineering University Aerospace Information Institute Beijing China Aerospace Engineering University Science and Technology on Complex Electronic System Simulation Laboratory Beijing China

ISBN: (纸本)9781665415989

Aiming at the complexity of space-based information system (SIS) effectiveness evaluation and the coupling and interaction of various combat capabilities, a data-driven operational effectiveness evaluation model is proposed. By introducing the PSO-BPNN to fit the performance evaluation I/O data, design the mapping relationship between the neural network input layer, hidden layer, output layer and hierarchical index system. On this basis, the affiliation relationship among the indicators at each level and the association relationship between the indicators are excavated, and the SIS effectiveness evaluation model is constructed. Taking the maritime integrated joint operations supported by space-based information as an example, the effectiveness data is obtained by using MATLAB, VENSIM and STK co-simulation. By quantitatively analyzing the coupling interaction between indexes, the operational effectiveness of SIS was evaluated, and the accuracy of the model and the feasibility of the evaluation method were verified. © 2021 IEEE.

关键词： MATLAB

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Operational Effectiveness Evaluation of Reconnaissance Satellite system based on system Dynamics Model 2

Operational Effectiveness Evaluation of Reconnaissance Satel...

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2nd IEEE International Conference on Information Technology, Big Data and Artificial Intelligence, ICIBA 2021

作者： Han, Chi Xiong, Wei Liu, Wenwen Yu, Xiaolan Jian, Ping Aerospace Information Institute Space Engineering University Beijing China Science and Technology on Complex Electronic System Simulation Laboratory Space Engineering University Beijing China

ISBN: (纸本)9781665428767

In order to study changes in the effectiveness of reconnaissance satellite system (RSS) in supporting maritime operations, based on the key factors of dynamic confrontation system of the offensive and defensive parties, the feedback relationships between variables are analyzed. According to the feedback relationship, a system dynamics (SD) model based on Lanchester equation was established and simulated on the VENSIM platform to compare and analyze operational effectiveness of different RSS allocation schemes. simulation analysis shows that RSS can increase the rate of detection and acquisition of information and accelerate the loss of the enemy. At the same time, when the sensor parameters are similar, increasing the number of weapons can significantly reduce the loss, which provides a certain theoretical support for decision-making analysis in combat. © 2021 IEEE.

关键词： Feedback

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Scenario-based analysis and probability assessment of sub-synchronous oscillation caused by wind farms with direct-driven wind generators

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Journal of Modern Power systems and Clean Energy 2019年第2期7卷 243-253页

作者： Zhi AN Chen SHEN Zetian ZHENG Feng LIU Xiaoqing CHANG Wei WEI Department of Electrical Engineering Tsinghua UniversityBeijingChina China State Key Laboratory of Power System and Generation Equipment BeijingChina Electric Power Research Institute of Sichuan Electric Power Company ChengduChina

Recently, explanations of the sub-synchronous oscillation(SSO) caused by wind farms based on directdriven wind generators(DDWGs) have been published in the literatures, in which the controller parameters of DDWGs and the system equivalent parameters play an important role. However, more than one set of parameters can cause weakly damped sub-synchronous modes. The most vulnerable and highly possible scenario is still unknown. To find scenarios that have potential oscillation risks, this paper proposes a small disturbance model of wind farms with DDWGs connected to the grid using a state-space modeling technique. Taguchi’s orthogonal array testing is introduced to generate different *** scenarios with different parameter settings that may lead to SSOs are found. A probabilistic analysis method based on the Gaussian mixture model is employed to evaluate the consistency of these scenarios with the actual accidents. Electromagnetic transient simulations are performed to verify the findings.

关键词： Direct-driven wind generator Subsynchronous oscillation Probabilistic assessment Randomness

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Transitional wave configurations between Type Ⅲ and Type Ⅳ oblique-shock/bow-shock interactions

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Chinese Journal of Aeronautics 2023年第3期36卷 96-106页

作者： Jun PENG Shuai LI Fan YANG Mingyue LIN Guilai HAN Zongmin HU State Key Laboratory of High-temperature Gas Dynamics Institute of MechanicsChinese Academy of SciencesBeijing 100190China The System Design Institute of Mechanical-Electrical Engineering Beijing 100854China School of Engineering Science University of Chinese Academy of SciencesBeijing 100049China

The interactions of oblique/bow shock waves are the key flow phenomena restricting the design and aerothermodynamic performance of high-speed *** Ⅲ and Type Ⅳ Shock/Shock Interactions(SSIs)have been extensively investigated,as such interactions can induce abnormal aerodynamic heating problems in hypersonic flows of *** transition process between these two distinct types of shock/shock interactions remains *** the present study,a subclass of shock/shock interaction configuration is revealed and defined as Type Ⅲ*** Ⅲa interaction can induce much more severe aerodynamic heating than a Type Ⅳ interaction which was ever reported to be the most serious in *** intense aerodynamic heating observed in this configuration highlights a new design point for the thermal protection system of hypersonic vehicles.A secondary Mach interaction between shock waves in the supersonic flow path of a Type Ⅲ configuration is demonstrated to be the primary mechanism for such a subclass of shock/shock interaction configuration.

关键词： Shock interactions Transitional configuration Aerodynamic heating Shear layer Mach interaction

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Climatic and Biotic Controls of Evapotranspiration Across Grassland Ecosystems on the Tibetan Plateau

SSRN

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SSRN 2025年

作者： Peng, Siyuan Yang, Yue Luo, Dengnan Zeng, Xiang Liang, Minqi Tao, Long Zhang, Guangru Li, Pan Liao, Weijie Guo, Qun Cao, Ruochen Li, Yuzhe Zhang, Weirong Hu, Zhongmin Hainan Baoting Tropical Rainforest Ecosystem Observation and Research Station School of Ecology Hainan University Haikou570228 China Department of Geography Faculty of Arts and Sciences Beijing Normal University Zhuhai519087 China Facility of Geographical Science Beijing Normal University Beijing100875 China Zhuhai Branch of State Key Laboratory of Earth Surface Processes and Resource Ecology Beijing Normal University Zhuhai519087 China School of Geography South China Normal University Shipai Campus Guangzhou510631 China School of Atmospheric Sciences Guangdong Province Data Center of Terrestrial and Marine Ecosystems Carbon Cycle Sun Yat-sen University Guangdong Zhuhai510245 China Key Lab of Ecosystem Network Observation and Modeling Institute of Geographic Sciences and Natural Resources Research Chinese Academy of Sciences Beijing100101 China College of Resources and Environment University of Chinese Academy of Sciences Beijing101408 China International Institute for Earth System Sciences Jiangsu Center for Collaborative Innovation in Geographical Information Resource Development and Application Nanjing University Jiangsu210023 China Jiangsu Provincial Key Laboratory of Geographic Information Science and Technology Key Laboratory for Land Satellite Remote Sensing Applications of Ministry of Natural Resources School of Geography and Ocean Science Nanjing University Jiangsu210023 China Key Laboratory of Land Surface Pattern and Simulation Institute of Geographical Sciences and Natural Resources Research Chinese Academy of Sciences Beijing China

Study region: The Tibetan Plateau in China, the Third Pole of the *** focus: Accurate descriptions of spatial variation in evapotranspiration (ET) and its components on the Tibetan Plateau (TP) are crucial for understanding the dynamics of the regional water cycle and energy balance. However, how various environmental factors affect ET and its components remains unclear. This study addresses this gap using observational data from 14 sites and employing the Shuttleworth-Wallace-Hu (SWH) model to examine the spatial relationships between ET, its components, and underlying *** hydrological insights for the region: The SWH model parameters were optimized using the Monte Carlo method, achieving a satisfactory model performance with an average R² of 0.75. The ratio of transpiration to ET was generally higher in alpine meadows (0.55) than alpine steppes (0.39). Across the TP, precipitation and the leaf area index together shaped spatial variation in ET and transpiration. Precipitation emerged as the primary driver of interannual variation in ET, while the leaf area index strongly regulated the proportion of ET accounted for by transpiration. Furthermore, above aridity index values of 0.73, grassland ecosystems transitioned from water to energy. This finding is significant as it challenges the common application of an aridity index value of 0.65 to distinguish arid from humid regions. It suggests that TP grasslands, with an AI of 0.65-0.73, remain primarily water-limited. © 2025, The Authors. All rights reserved.

关键词： Monte Carlo methods

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Bug localization based on syntactical and semantic information of source code

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Journal of systems engineering and Electronics 2023年第1期34卷 236-246页

作者： YAN Xuefeng CHENG Shasha GUO Liqin College of Computer Science Technology Nanjing University of Aeronautics and AstronauticsNanjing 211106China Collaborative Innovation Center of Novel Software Technology and Industrialization Nanjing 211106China State Key Laboratory of Intelligent Manufacturing System Technology Beijing Institute of Electronic System EngineeringBeijing 100854China

The existing software bug localization models treat the source file as natural language, which leads to the loss of syntactical and structure information of the source file. A bug localization model based on syntactical and semantic information of source code is proposed. Firstly, abstract syntax tree(AST) is divided based on node category to obtain statement sequence. The statement tree is encoded into vectors to capture lexical and syntactical knowledge at the statement ***, the source code is transformed into vector representation by the sequence naturalness of the statement. Therefore,the problem of gradient vanishing and explosion caused by a large AST size is obviated when using AST to the represent source code. Finally, the correlation between bug reports and source files are comprehensively analyzed from three aspects of syntax, semantics and text to locate the buggy code. Experiments show that compared with other standard models, the proposed model improves the performance of bug localization, and it has good advantages in mean reciprocal rank(MRR), mean average precision(MAP) and Top N Rank.

关键词： bug report abstract syntax tree code representation software bug localization

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Dynamical Behavior of an Atomic Beam Interacting with a Fock state Light Field

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Chinese Physics Letters 2010年第1期27卷 100-103页

作者：李犇陈景标 Institute of Quantum Electronics and State Key Laboratory of Advanced Optical Communication System & Network School of Electronics Engineering & Computer Science Peking University Beijing 100871

The collapse and revival of evolution with photon number of population inversion in the case of an atomic beam with velocity distribution interacting with a single-mode and Fock-state light field is investigated by full quantum theory. Compared to the previously reported coherent state case [Li B and Chen J B Chin. Phys. Lett. 26（2009）123203], which was induced by evolution with coupling strength of population inversion, in the case under consideration there exists Poisson distribution of photon numbers and atomic velocity distribution in the beam. Moreover, we prove that above, the collapse and revival have an analogy with conventional collapse and revival [Eberly J H et al. Phys. Rev. Lett. 44（1980）1323] in both the mathematical expression and physical significance.

关键词： Chinese climate network complex systems small world community

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Ozone and secondary organic aerosol formation potential from anthropogenic volatile organic compounds emissions in China

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Journal of Environmental Sciences 2017年第3期29卷 224-237页

作者： WenJing Wu Bin Zhao Shuxiao Wang Jiming Hao State Key Joint Laboratory of Environment Simulation and Pollution Control School of EnvironmentTsinghua UniversityBeijing 100084China State Environmental Protection Key Laboratory of Sources and Control of Air Pollution Complex Beijing 100084China Collaborative Innovation Center for Regional Environmental Quality Tsinghua UniversityBeijin9 100084China Joint Institute for Earth System Science and Engineering Department of Atmospheric and Oceanic SciencesUniversity of CaliforniaLos AngelesCA 90095USA.

Volatile organic compounds （VOCs） are major precursors for ozone and secondary organic aerosol （SOA）, both of which greatly harm human health and significantly affect the Earth＇s climate. We simultaneously estimated ozone and SOA formation from anthropogenic VOCs emissions in China by employing photochemical ozone creation potential （POCP） values and SOA yields. We gave special attention to large molecular species and adopted the SOA yield curves from latest smog chamber experiments. The estimation shows that alkylbenzenes are greatest contributors to both ozone and SOA formation （36.0% and 51.6%, respectively）, while toluene and xylenes are largest contributing individual VOCs. Industry solvent use, industry process and domestic combustion are three sectors with the largest contributions to both ozone （24.7%, 23.0% and 17.8%, respectively） and SOA （22.9%, 34.6% and 19.6%, respectively） formation. In terms of the formation potential per unit VOCs emission, ozone is sensitive to open biomass burning, transportation, and domestic solvent use, and SOA is sensitive to industry process, domestic solvent use, and domestic combustion. Biomass stoves, paint application in industrial protection and buildings, adhesives application are key individual sources to ozone and SOA formation, whether measured by total contribution or contribution per unit VOCs emission. The results imply that current VOCs control policies should be extended to cover most important industrial sources, and the control measures for biomass stoves should be tightened. Finally, discrepant VOCs control policies should be implemented in different regions based on their ozone/aerosol concentration levels and dominant emission sources for ozone and SOA formation potential.

关键词： Volatile organic compounds （VOCs）OzoneSecondary organic aerosol （SOA）Formation potentialControl strategy

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