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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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Finite-Time Stability for Fractional-Order Bidirectional Associative Memory Neural Networks with Time Delays

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Communications in Theoretical Physics 2017年第2期67卷 137-142页

作者： Chang-Jin Xu Guizhou Key Laboratory of Economics System Simulation Guizhou University of Finance and Economics Guiyang 550004 China School of Mathematics and Statistics Henan University of Science and Technology Luoyang 471023 China School of Mathematics and Statistics Guizhou University of Finance and Economics Guiyang 550004 China

This paper is concerned with fractional-order bidirectional associative memory(BAM) neural networks with time delays. Applying Laplace transform, the generalized Gronwall inequality and estimates of Mittag–Leffler functions, some sufficient conditions which ensure the finite-time stability of fractional-order bidirectional associative memory neural networks with time delays are obtained. Two examples with their simulations are given to illustrate the theoretical findings. Our results are new and complement previously known results.

关键词： BAM neural networks finite-time stability time delay Gronwall inequality

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New WHO global air quality guidelines help prevent premature deaths in China

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National science Review 2022年第4期9卷 10-12页

作者： Tao Xue Guannan Geng Xia Meng Qingyang Xiao Yixuan Zheng Jicheng Gong Jun Liu Wei Wan Qiang Zhang Haidong Kan Shiqiu Zhang Tong Zhu Institute of Reproductive and Child Health/National Health Commission Key Laboratory of Reproductive Health and Department of Epidemiology and Biostatistics School of Public HealthPeking University State Key Joint Laboratory of Environmental Simulation and Pollution Control School of EnvironmentTsinghua University School of Public Health Key Laboratory of Public Health Safety of the Ministry of Educationand Key Laboratory of Health Technology Assessment of the Ministry of HealthFudan University Center of Air Quality Simulation and System Analysis Chinese Academy of Environmental Planning College of Environmental Sciences and Engineering Peking University School of Energy and Environmental Engineering University of Science and Technology Beijing Clean Air Asia Ministry of Education Key Laboratory for Earth System Modeling Department of Earth System ScienceTsinghua University

The air quality guidelines （AQGs） issued by the World Health Organization （WHO） in 2005 are key references for the National Ambient Air Quality Standards （NAAQSs） in *** 22September 2021,the WHO issued new AQGs （NAQGs）[1],which propose more stringent targets to control exposure to multiple air pollutants,including fine particulate matter (PM2.5) and ozone （O3）,to which,in 2019,451 million premature deaths,globally,were attributable [2].

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Optimal Controller Design for Non-Affine Nonlinear Power systems with Static Var Compensators for Hybrid UAVs

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Tsinghua science and technology 2022年第1期27卷 196-206页

作者： Yanchu Li Qingqing Ding Shufang Li Stanimir Valtchev Beijing Key Laboratory of Network System Architecture and Convergence Beijing Laboratory of Advanced Information Networkand School of Information&Communication EngineeringBeijing University of Posts and TelecommunicationsBeijing 100876China State Key Laboratory of Control and Simulation of Power System and Generation Equipments Tsinghua UniversityBeijing 100084China the Nova School of Science and Technology(FCT/UNL) Caparica 2829-516LisbonPortugal Technical University of Sofia(TUS) Sofia 2125Bulgaria

A generalized non-affine nonlinear power system model is presented for a single machine bus power system with a Static Var Compensator(SVC)or State Var system(SVS)for hybrid Unmanned Aerial Vehicles(UAVs).The model is constructed by differential algebraic equations on the MATLAB-Simulink platform with the programming technique of its *** the inverse system method and the Linear Quadratic Regulation(LQR),an optimized SVC controller is *** simulations under three fault conditions show that the proposed controller can effectively improve the power system transient performance.

关键词： Static Var Compensator(SVC) Unmanned Aerial Vehicles(UAV) power system non-affine nonlinear control inverse system method Linear Quadratic Regulation(LQR)

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Design of optimal trajectory transition controller for thrust-vectored V/STOL aircraft

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science China(Information sciences) 2021年第3期64卷 235-237页

作者： Zhiqiang CHENG Jihong ZHU Xiaming YUAN Xiangyang WANG Department of Computer Science and Technology Tsinghua University Key Laboratory of Complex Ship System Simulation

Dear editor,In recent years, vertical and/or short take-off and landing(V/STOL) aircraft have attracted much attention because they combine the efficiency of fixed-wing vehicles with the flexibility of traditional ver... 详细信息

关键词： backward propagation V/STOL transition control thrust-vector optimal trajectory

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Drought frequency, intensity, and exposure have increased due to historical land use and land cover changes

Communications Earth & Environment

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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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Procedural level of detail enhancement algorithm of ChunkLod real time terrain rendering

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Xitong Fangzhen Xuebao / Journal of system simulation 2008年第21期20卷 5763-5766+5773页

作者： Shen, Yan-Chun Zhu, You-Hong Wen, Zhuan-Ping Cao, Li Laboratory of VR and System Simulation Beijing Information Science and Technology University Beijing 100085 China

The ChunkLod algorithm was researched. Because the technology lacked process that viewpoint is near to the ground, the algorithm was adopted taking massive model as processing unit and the procedural enhancement of LOD was proposed. And the algorithm increased the efficiency of rendering by combining the local triangle surface simplified algorithm and the error evaluation and control algorithm, and it avoided large-scale computing caused by over-LOD. Finally, it shows that the visual effect of terrain information is expressed well when the algorithm is working virtually-the geography resources information management system, for example. The experiment indicates that the improved level of detail enhancement of ChunkLod is a practical terrain algorithm with total levels of detail technology.

关键词： ChunkLod Level of detail enhancement Level of details Real time terrain rendering

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Multiuser interference suppression for the uplink of interleaved MIMO OFDMA

Multiuser interference suppression for the uplink of interle...

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2013 International Conference on Communications, Circuits and systems, ICCCAS 2013

作者： Han, Wei Wang, Gang System Simulation Department Zhong Xing Telecommunication Equipment Corporation Shanghai 211203 China National Key Laboratory of Science and Technology on Communications University of Electronic Science and Technology of China Chengdu 610054 China

ISBN: (纸本)9781479930517

In the uplink of multiple-input multiple-output (MIMO) orthogonal frequency division multiple access (OFDMA) systems, multiuser interference (MUI) occurs due to carrier frequency offsets (CFOs). In this paper, a novel scheme is presented to suppress MUI for the interleaved MIMO OFDMA system. The first stage is to compensate the multiple CFOs, which is based on a calculation of optimum CFO correction value maximizing the average signal-to-interference ratio (SIR). And the second stage uses minimum mean square error (MMSE) frequency domain equalizer (FDE), considering the residual MUI as additive noise, to further improve the systems' performance. simulation results show that the proposed scheme exhibits a significant improvement over conventional scheme. © 2013 IEEE.

关键词： Frequency division multiple access

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Dissecting the contributions of organic nitrogen aerosols to global atmospheric nitrogen deposition and implications for ecosystems

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National science Review 2023年第12期10卷 124-136页

作者： Yumin Li Tzung-May Fu Jian Zhen Yu Xu Yu Qi Chen Ruqian Miao Yang Zhou Aoxing Zhang Jianhuai Ye Xin Yang Shu Tao Hongbin Liu Weiqi Yao Shenzhen Key Laboratory of Precision Measurement and Early Warning Technology for Urban Environmental Health Risks School of Environmental Science and Engineering Southern University of Science and Technology Guangdong Provincial Observation and Research Station for Coastal Atmosphere and Climate of the Greater Bay Area Southern University of Science and Technology Division of Environment and Sustainability Hong Kong University of Science and Technology National Center for Applied Mathematics Shenzhen Department of Chemistry Hong Kong University of Science and Technology State Key Joint Laboratory of Environmental Simulation and Pollution Control International Joint Laboratory for Regional Pollution Control College of Environmental Sciences and Engineering Peking University Frontier Science Center for Deep Ocean Multispheres and Earth System and Physical Oceanography Laboratory Ocean University of China College of Oceanic and Atmospheric Sciences Ocean University of China Department of Ocean Science Hong Kong University of Science and Technology Department of Ocean Science and Engineering Southern University of Science and Technology

Atmospheric deposition of particulate organic nitrogen（ONp） is a significant process in the global nitrogen cycle and may be pivotally important for N-limited ***,past models largely overlo oked the spatial and chemical inhomogeneity of atmospheric ONpand were thus deficient in assessing global *** constructed a comprehensive global model of atmospheric gaseous and particulate organic nitrogen（ON）,including the latest knowledge on emissions and secondary *** this model,we simulated global atmospheric ONpabundances consistent with *** estimated global atmospheric ON deposition was 26 Tg N yr-1,predominantly in the form of ONp(23 Tg N yr-1)and mostly from wildfires（37%）,oceans（22%） and aqueous productions（17%）.Globally,ONpcontributed as much as 40% to 80% of the total N deposition downwind of biomass-burning *** ONpdeposition thus constituted the dominant external N supply to the N-limited boreal forests,tundras and the Arctic Ocean,and its importance maybe amplified in a future warming climate.

关键词： organic nitrogen aerosol secondary organic nitrogen biomass burning

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Miniaturization Design of TEM Horn Antenna for Ground-Penetrating Radar 15

Miniaturization Design of TEM Horn Antenna for Ground-Penetr...

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15th International Conference on Microwave and Millimeter Wave technology, ICMMT 2023

作者： Li, Zhi-Hao Ma, Jing Wu, Jin Huang, Jia-Jia Lu, Yong-Han Peng, Lin Guangxi Guilin541004 China Education Department of Guangxi Zhuang Autonomous Region Guangxi Guilin541004 China Beijing Simulation Center Science and Technology on Special System Simulation Laboratory Beijing100854 China

ISBN: (纸本)9798350338874

This paper presents a miniaturized TEM horn antenna for ground penetrating radar (GPR). First, an exponential gradient horn antenna is designed with a low cut-off frequency of 0.45 GHz. Then, the low cut-off frequency is decreased to 0.19 GHz through curve structural loading and lens loading without increasing the size of the horn. The antenna size is 378.49 mm × 359.07 mm × 386.06 mm, corresponding to 0.226 λ1 × 0.238 λ1 × 0.243 λ1 ( λ1 is the wavelength corresponding to the lowest frequency of the antenna). The results show that the working bandwidth of the antenna is 0.19-3GHz, and it has a good radiation pattern in the band, with a peak gain of 12.4dBi, which would be a good candidate for GPR. © 2023 IEEE.

关键词： Horn antennas

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