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Development of database of real-world diesel vehicle emission factors for China

Journal of Environmental Sciences 2015年第5期27卷 209-220页

作者： Xianbao Shen Zhiliang Yao Qiang Zhang David Vance Wagner Hong Huo Yingzhi Zhang Bo Zheng Kebin He State Key Joint Laboratory of Environment Simulation and Pollution Control School of Environment Tsinghua University School of Food and Chemical Engineering Beijing Technology and Business University Ministry of Education Key Laboratory for Earth System Modeling Center for Earth System Science Tsinghua University International Council on Clean Transportation (ICCT) Institute of Energy Environment and Economy Tsinghua University State Environmental Protection Key Laboratory of Sources and Control of Air Pollution Complex Tsinghua University

A database of real-world diesel vehicle emission factors, based on type and technology, has been developed following tests on more than 300 diesel vehicles in China using a portable emission measurement system. The database provides better understanding of diesel vehicle emissions under actual driving conditions. We found that although new regulations have reduced real-world emission levels of diesel trucks and buses significantly for most pollutants in China, NOx emissions have been inadequately controlled by the current standards, especially for diesel buses, because of bad driving conditions in the real world. We also compared the emission factors in the database with those calculated by emission factor models and used in inventory studies. The emission factors derived from COPERT（Computer Programmer to calculate Emissions from Road Transport） and MOBILE may both underestimate real emission factors, whereas the updated COPERT and PART5（Highway Vehicle Particulate Emission modeling Software） models may overestimate emission factors in China. Real-world measurement results and emission factors used in recent emission inventory studies are inconsistent,which has led to inaccurate estimates of emissions from diesel trucks and buses over recent years. This suggests that emission factors derived from European or US-based models will not truly represent real-world emissions in China. Therefore, it is useful and necessary to conduct systematic real-world measurements of vehicle emissions in China in order to obtain the optimum inputs for emission inventory models.

关键词： Diesel vehicle Emission factor Portable emission measurement system Database China

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Research on survivability analysis method of spatial information network based on dynamic cumulative model 6

Research on survivability analysis method of spatial informa...

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6th International Conference on Electronic Information Technology and Computer Engineering, EITCE 2022

作者： Zhao, Zhongwen Li, Guodong Lu, Di Key Laboratory of Complex Electronic System Simulation Space Engineering University Beijing China

ISBN: (纸本)9781450397148

In view of the problem that multifunctional hierarchy and dynamic characteristics are not considered simultaneously in the research methods of survivability of spatial information networks. This paper first summarizes the main methods of survivability research and three main attack strategies. Secondly, the idea of data flow and the method of time accumulation graph were integrated into the spatial information network model, and the multi-layer dynamic spatial network accumulation model was established. Finally, the navigation satellite network, communication satellite network and remote sensing satellite network are taken as examples to construct the spatial information network simulation plan, and the attack is carried out according to the three attack strategies, and the survivability of the spatial information network is analyzed. The experimental results verify the rationality of the proposed method and the effectiveness of the index, and explore the rules. © 2022 Association for Computing Machinery.

关键词： Satellites

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

作者： Peng, Yafei Yang, Fande Aerospace Engineering University Complex Electronic System Simulation Key Laboratory Beijing China

ISBN: (纸本)9781665415989

In order to improve the decision-making ability of aerospace commanders, aerospace command decision-making theory was studied from the concepts and characteristics of space command decision-making, and various situation information involved in aerospace command decision-making was analyzed, a general process for aerospace command decision-making was established. and the auxiliary technical means of aerospace command decision-making was summarized. It has laid a foundation for aerospace command and decision-making related theories, which is convenient for commanders to clarify the aerospace command and decision-making process, obtain situational knowledge required for decision-making, and improve the timeliness of decision-making. © 2021 IEEE.

关键词： Decision making

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Mechanical properties of self-irradiated single-crystal copper

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Chinese Physics B 2014年第3期23卷 435-440页

作者：李维娜薛建明王建祥段慧玲 State Key Laboratory for Turbulence and Complex System Department of Mechanics and Aerospace Engineering College of EngineeringPeking University State Key Laboratory of Nuclear Physics and Technology School of Physics Peking University Key Laboratory of High Energy Density Physics Simulation Center for Applied Physics and Technology Peking University

Molecular dynamics simulations are performed to investigate the influence of irradiation damage on the mechanical properties of copper. In the simulation, the energy of primary knocked-on atoms （PKAs） ranges from 1 to 10 keV, and the results indicate that the number of point defects （vacancies and interstitials） increases linearly with the PKA energy. We choose three kinds of simulation samples： un-irradiated and irradiated samples, and comparison samples. The un-irradiated samples are defect-free, while irradiation induces vacancies and interstitials in the irradiated samples. It is found that due to the presence of the irradiation-induced defects, the compressive Young modulus of the single-crystal Cu increases, while the tensile Young modulus decreases, and that both the tensile and compressive yield stresses experience a dramatic decrease. To analyze the effects of vacancies and interstitials independently, the mechanical properties of the comparison samples, which only contain randomly distributed vacancies, are investigated. The results indicate that the vacancies are responsible for the change of Young modulus, while the interstitials determine the yield strain.

关键词： irradiation damage single crystal mechanical property molecular dynamics simulation

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Air pollution characteristics and their relationship with emissions and meteorology in the Yangtze River Delta region during 2014–2016

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Journal of Environmental Sciences 2019年第9期31卷 8-20页

作者： Tao Ma Fengkui Duan Kebin He Yu Qin Dan Tong Guannan Geng Xuyan Liu Hui Li Shuo Yang Siqi Ye Beiyao Xu Qiang Zhang Yongliang Ma State Key Joint Laboratory of Environment Simulation and Pollution Control School of Environment State Environmental Protection Key Laboratory of Sources and Control of Air Pollution Complex Beijing Key Laboratory of Indoor Air Quality Evaluation and Control Tsinghua University Beijing 100084 China Ministry of Education Key Laboratory for Earth System Modeling Department of Earth System Science Tsinghua University Beijing 100084 China National Satellite Meteorological Center Beijing 100081 China College of Resources and Environmental Sciences China Agricultural University Beijing 100094 China

With rapid economic growth and urbanization, the Yangtze River Delta(YRD) region in China has experienced serious air pollution challenges. In this study, we analyzed the air pollution characteristics and their relationship with emissions and meteorology in the YRD region during 2014–2016. In recent years, the concentrations of all air pollutants, except O3,decreased. Spatially, the PM2.5, PM10, SO2, and CO concentrations were higher in the northern YRD region, and NO2 and O3 were higher in the central YRD region. Based on the number of non-attainment days(i.e., days with air quality index greater than 100), PM2.5 was the largest contributor to air pollution in the YRD region, followed by O3, PM10, and ***, particulate matter pollution has declined gradually, while O3 pollution *** conditions mainly influenced day-to-day variations in pollutant concentrations. PM2.5 concentration was inversely related to wind speed, while O3 concentration was positively correlated with temperature and negatively correlated with relative *** air quality improvement in recent years was mainly attributed to emission *** 2014–2016, PM2.5, PM10, SO2, NOx, CO, NH3, and volatile organic compound(VOC)emissions in the YRD region were reduced by 26.3%, 29.2%, 32.4%, 8.1%, 15.9%, 4.5%, and0.3%, respectively. Regional transport also contributed to the air pollution. During regional haze periods, pollutants from North China and East China aggravated the pollution in the YRD region. Our findings suggest that emission reduction and regional joint prevention and control helped to improve the air quality in the YRD region.

关键词： Air pollution Spatiotemporal variation Meteorological condition Emission inventory Regional transport Yangtze River Delta

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食品系统与气候变化、空气污染之间的相互作用综述（英文）

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Engineering 2025年第1期 215-233页

作者： Chaopeng Hong Rui Zhong Mengyao Xu Peidong He Huibin Mo Yue Qin Danna Shi Xinlei Chen Kebin He Qiang Zhang Shenzhen Key Laboratory of Ecological Remediation and Carbon Sequestration Institute of Environment and Ecology Shenzhen International Graduate School Tsinghua University State Environmental Protection Key Laboratory of Sources and Control of Air Pollution Complex College of Environmental Sciences and Engineering Peking University Institute of Data and Information Shenzhen International Graduate School Tsinghua University State Key Joint Laboratory of Environment Simulation and Pollution Control School of Environment Tsinghua University Ministry of Education Key Laboratory for Earth System Modeling Department of Earth System Science Tsinghua University

Food systems are deeply affected by climate change and air pollution, while being key contributors to these environmental challenges. Understanding the complex interactions among food systems, climate change, and air pollution is crucial for mitigating climate change, improving air quality, and promoting the sustainable development of food systems. However, the literature lacks a comprehensive review of these interactions, particularly in the current phase of rapid development in the field. To address this gap, this study systematically reviews recent research on the impacts of climate change and air pollution on food systems, as well as the greenhouse gas and air pollutant emissions from agri-food systems and their contribution to global climate change and air pollution. In addition, this study summarizes various strategies for mitigation and adaptation, including adjustments in agricultural practices and food supply chains. Profound changes in food systems are urgently needed to enhance adaptability and reduce emissions. This review offers a critical overview of current research on the interactions among food systems, climate change, and air pollution and highlights future research directions to support the transition to sustainable food systems.

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A credibility allocation approach of complex simulation systems 35

A credibility allocation approach of complex simulation syst...

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35th European modeling and simulation Symposium, EMSS 2023

作者： Zhang, Huan Li, Wei Geng, HuaPin Ma, Ping Yang, Ming Control and Simulation Center Harbin Institute of Technology Harbin150080 China National Key Laboratory of Modeling and Simulation for Complex Systems Harbin150080 China Science and Technology on Complex System Control and Intelligent Agent Cooperation Laboratory Beijing100074 China

ISBN: (纸本)9788885741881

complex simulation systems usually need to satisfy the credibility requirements and the credibility of complex simulation systems is inextricably linked to the credibility of simulation sub-systems. Hence, in order to guarantee the credibility of complex simulation systems meets requirements, it is necessary to allocate the credibility of simulation sub-systems. complex simulation systems are composed of several correlative simulation sub-systems and their credibility has correlation relationships, which makes it difficult to obtain the credibility of simulation sub-systems quickly. The existing works mostly ignore the relationships between the sub-systems and are difficult to generate the credibility allocation results of simulation sub-systems. In this paper, we model the credibility allocation problem as a probabilistic inference problem based on the pairwise Markov random field (PMRF). In addition, we apply several inference algorithms to perform the inference exactly and approximately in the credibility PMRF. Finally, experiments are conduted on the air defense combat complex simulation system, and the experiment results demonstrate that the proposed method can obtain the credibility allocation results quickly and accurately. © 2023 The Authors.

关键词： Inference engines

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On the Fourier approximation method for steady water waves

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Acta Oceanologica Sinica 2014年第5期33卷 37-47页

作者： ZHAO Hongjun SONG Zhiyao LI Ling KONG Jun State Key Laboratory of Hydrology-Water Resources and Hydraulic Engineering College of HarborCoastal and Offshore Engineering Hohai University Key Laboratory of Virtual Geographic Environment Key Laboratory for Numerical Simulation of Largescale Complex System Nanjing Normal University School of Engineering The University of Queensland

A computational method for steady water waves is presented on the basis of potential theory in the physical plane with spatial variables as independent quantities. The finite Fourier series are applied to approximating the free surface and potential function. A set of nonlinear algebraic equations for the Fourier coefficients are derived from the free surface kinetic and dynamic boundary conditions. These algebraic equations are numerically solved through Newton＇s iterative method, and the iterative stability is further improved by a relaxation technology. The integral properties of steady water waves are numerically analyzed, showing that （1） the set-up and the set-down are both non-monotonic quantities with the wave steepness, and （2） the Fourier spectrum of the free surface is broader than that of the potential function. The latter further leads us to explore a modification for the present method by approximating the free surface and potential function through different Fourier series, with the truncation of the former higher than that of the latter. Numerical tests show that this modification is effective, and can notably reduce the errors of the free surface boundary conditions.

关键词： steady water waves Fourier series Newton＇s method relaxation technology wave properties

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Viscous Rayleigh-Taylor instability with and without diffusion effect

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Applied Mathematics and Mechanics(English Edition) 2017年第2期38卷 263-270页

作者： Chenyue XIE Jianjun TAO Ji LI Center for Applied Physics and Technology (CAPT)-MOE Key Laboratory of High Energy Density Physics Simulation (HEDPS) State Key Laboratory for Turbulence and Complex System (SKLTCS) Department of Mechanics and Engineering ScienceCollege of Engineering Peking University Department of Engineering University of Cambridge

The approximate but analytical solution of the viscous Rayleigh-Taylor insta- bility （RTI） has been widely used recently in theoretical and numerical investigations due to its clarity. In this paper, a modified analytical solution of the growth rate for the viscous RTI of incompressible fluids is obtained based on an approximate method. Its accuracy is verified numerically to be significantly improved in comparison with the previous one in the whole wave number range for different viscosity ratios and Atwood numbers. Fur- thermore, this solution is expanded for viscous RTI including the concentration-diffusion effect.

关键词： viscous Rayleigh-Taylor instability （RTI） dispersion relation diffusioneffect

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Architecture transformation research on joint border defense systems-of-systems 2021

Architecture transformation research on joint border defense...

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2021 5th International Conference on Management Engineering, Software Engineering and Service Sciences, ICMSS 2021

作者： Zhang, Mengmeng Yi, Shuanghui Lin, Menglong Chen, Honghui Science and Technology on Information Systems Engineering Laboratory China National Key Laboratory for Complex System Simulation China

ISBN: (纸本)9781450389709

Currently, with the deepening of development and open of China's border, issues of border joint defense become increasingly arduous. Traditional means of cooperation and coordination are far from being able to align requirements;information systems of different joint defense units are difficult to interconnect and interoperate;the previous results of joint defense informatization are difficult to inherit. The main reason is the lack of border joint defense information construction with a top-level design approach. Via the lens of top-level design, this paper establishes a multi-viewpoint architecture framework and transformation process, develops the as-is and to-be joint defense architecture, and finally analyzes transformation principles from the as-is architecture to to-be architecture. This paper mainly explores the architecture transformation mechanisms under the border joint defense scenario. © 2021 ACM.

关键词： Architecture

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