检索结果-内蒙古大学图书馆

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

来源：评论

学校读者我要写书评

暂无评论

Evolution of Subkilometer-scale Impact Craters on the Lunar Maria as Constrained from Mini-RF Data and Topographic Degradation Model

引用

Research in Astronomy and Astrophysics 2023年第12期23卷 19-33页

作者：孙庆海法文哲祝梦华都骏 State Key Laboratory of Lunar and Planetary Sciences Macao University of Science and TechnologyMacao 999078China CNSA Macao Center for Space Exploration and Science Macao 999078China Institute of Remote Sensing and Geographical Information System School of Earth and Space SciencesPeking UniversityBeijing 100871China State Key Laboratory of Space Weather National Space Science CenterChinese Academy of SciencesBeijing 100190China

Physical properties(e.g.,ejecta size and distribution)of impact craters are crucial and essential to understanding the ejecta excavation and deposition process,estimating rock breakdown rate,and revealing their evolution ***,whether these physical properties are scale-dependent and how they evolve in different radial regions needs further *** this study,we first investigated the physical properties and evolution of subkilometer(D≤800 m)craters on lunar maria based on the radar circular polarization ratio(CPR).In addition,we estimated the periods over which rocks and blocky ejecta are exposed and buried in the shallow subsurface layer(termed as exposure time)in different radial regions and assessed the retention time and degradation states for potential radar anomalous *** found that in the central region of craters,the largest median CPR occurs after an 80 Myr delay following crater *** the rim region,there is no obvious CPR peak in the first100 Ma,whereas in the upper wall region,an evident CPR peak occurs beyond 100 Ma and could last over one billion *** addition,the probable exposure time of rocks and blocky ejecta is estimated to be~2.0 Gyr(central region),~2.7 Gyr(upper wall region),~2.1 Gyr(rim region),and~0.6 Gyr(continuous ejecta blanket region).We also propose that the retention time of radar anomalous craters depends on the crater size,whereas their degraded states are independent of crater size.

关键词： Moon-planets and satellites surfaces-planets and satellites physical evolution

来源：评论

学校读者我要写书评

暂无评论

Application of high frequency scattering predication method in MMWSS

Application of high frequency scattering predication method ...

引用

International Conference on Microwave and Millimeter Wave technology Proceedings

作者： J. K. Nie L. X. Guo H. Zhao J. Ma J. D. Fei School of Science Xidian University Xi'an Shaanxi China Key Laboratory on Space System Simulation Beijing Simulation Center Beijing China

A radiation model of millimeter wave antenna is established in this paper. The electromagnetic field distribution on the seeker antenna is calculated in MMWSS based on PO method. According the numerical results, when target is in the near-field of antenna, the characteristic of echo amplitude has an obvious effect of multi-scattering points effect.

关键词： Missiles Scattering Surface waves Antenna radiation patterns Mathematical model Millimeter wave technology

来源：评论

学校读者我要写书评

暂无评论

Research on requirement elicitation model of high-end equipment based on requirement classification under Internet and big data environment

Research on requirement elicitation model of high-end equipm...

引用

2016 4th International Conference on Machinery,Materials and Information technology Applications(ICMMITA 2016)

作者： Yu GUO Junting WU Ke-wei YANG Lixin Yu College of Information System and Management National University of Defense Technology Science and Technology on Special System Simulation Laboratory Beijing Simulation Center

ISBN: (纸本)9781510835467

Currently, Internet and big data as the representative of emerging technologies are widely penetrated into every aspect of the high-end equipment manufacturing industry. Considering the characteristics of multi-source, personalized and potential for high-end equipment, this paper focuses on requirement elicitation in the background of Internet, and proposes a high-end equipment requirement elicitation model based on requirement classification, which stands on the perspective of management to study the high-end equipment requirement elicitation. First, we classify the user's need, and then different technical means are taken orienting different types of needs. In this paper, according to users' master degree of requirement, requirements can be divided into instant user requirement and potential user requirement. For instant user requirement, we design a requirement interaction platform based on Internet;For potential user requirement, a requirement mining model based on the open source information of the Internet is established. Eventually, a complete user requirement program is integrated. In conclusion, the idea of classifying the requirements provides a new perspective on requirement elicitation of high-end equipment.

关键词： high-end equipment Internet requirement elicitation requirement classification

来源：评论

学校读者我要写书评

暂无评论

Collaborative Filtering Recommendation Algorithm of Weaponry Based on Knowledge Graph

Collaborative Filtering Recommendation Algorithm of Weaponry...

引用

Information technology,Big Data and Artificial Intelligence (ICIBA), International Conference on IEEE International Conference on

作者： Xiao Li Desheng Liu Qing Chang Science and Technology on Complex Electronic System Simulation Laboratory Space Engineering University Beijing

ISBN: (纸本)9781665428781

Nowadays, modern warfare has changed from weapon-centric operations to network-centric system operations, which has led to the phenomenon of sea-level quantification of weaponry. It is an important research topic for combat commanders to select suitable weaponry from a large number of available resources when facing combat tasks. Recommendation technology is a solution to this problem, which can effectively solve the problem of information overload, so that combat commanders do not produce the phenomenon of “information loss”, in the shortest possible time to make the right decision. Therefore, this paper proposes a collaborative filtering recommendation algorithm for weaponry based on the knowledge graph and the idea of collaborative filtering. In this algorithm, the knowledge graph provides a clear data model with various association relationships, and the collaborative filtering algorithm can realize it without relying on professional experience, which can realize the recommendation process more actively, faster and more intelligently.

关键词： Weapons Collaborative filtering systems operation Conferences Filtering algorithms Big Data Information filters

来源：评论

学校读者我要写书评

暂无评论

Topological Connectivity Analysis on Freight Transportation Networks

Topological Connectivity Analysis on Freight Transportation ...

引用

作者： Xi-sheng SHEN Xiao-fang WANG Lian-yi ZHANG Xi-fu WANG School of Traffic and Transportation Beijing Jiaotong University School of Business Renmin University of China Science and Technology on Space System Simulation Laboratory Beijing Simulation Center

The connections between nodes in Freight Transportation Networks(FTNs) are highly complex. With the topological modelling of real world FTNs, this paper introduces quantitative indicators, such as degree distribution and edge/node betweenness centrality, to analyze the topological connectivity. The exponential laws of degree distribution and edge/node betweenness centrality are shown by numerical results on the coal transportation network in Shanxi, China.

关键词： Topological connectivity Degree distribution Betweenness Freight transportation networks

来源：评论

学校读者我要写书评

暂无评论

Robust Analysis of Freight Comprehensive Transportation Networks

Robust Analysis of Freight Comprehensive Transportation Netw...

引用

2019 International Conference on Applied Mathematics, Modeling, simulation and Optimization(AMMSO 2019)

作者： Xi-sheng SHEN Xiao-fang WANG Xi-fu WANG School of Traffic and Transportation Beijing Jiaotong University Science and Technology on Space System Simulation Laboratory Beijing Simulation Center School of Business Renmin University of China

The robustness of Freight Comprehensive Transportation Networks(FCTNs) refers to the ability that FCTNs can maintain their function or performance tolerating perturbations from uncertainties. To evaluate the robustness of FCTNs, this paper proposes several quantitative indicators including accessibility, delivery, carrying capacity and transferring capacity. Numerical results based on the case of coal comprehensive transportation networks in Shanxi, China show the effectiveness of the proposed method.

关键词： Robust analysis Freight Comprehensive Transportation Networks Evaluation indicators

来源：评论

学校读者我要写书评

暂无评论

Semi-physical simulation experiment on the on-orbit capture of tumbling uncooperative target spacecraft 69

Semi-physical simulation experiment on the on-orbit capture ...

引用

69th International Astronautical Congress: #InvolvingEveryone, IAC 2018

作者： Xie, Yongchun Wang, Yunpeng Yang, Baohua Beijing Institute of Control Engineering Beijing100190 China Science and Technology on Space Intelligent Control Laboratory Beijing China Tianjin Key Laboratory of Microgravity and Hypogravity Environment Simulation Technology Tianjin100190 China China Aerospace Science and Technology Corporation Beijing China

A semi-physical simulation experiment is introduced in this paper. The experiment simulates the on-orbit capture of tumbling uncooperative target satellite. The chaser spacecraft (or service spacecraft) is a satellite equipped with a 7 degree of freedom (DOF) manipulator and a relative pose measure sensor. A capture tool is installed at the end of the manipulator. It can capture the nozzle of the target. The relative posse measure sensor can measure the relative position and attitude between the chaser and target spacecrafts. The experiment is carried out on a novel semi-physical simulation system, whose core equipment is a novel 9 DOF motion simulator platform. One main feature of this simulator is that it can simulate the tumbling motion of the satellite. Copyright © 2018 by the International Astronautical Federation (IAF). All rights reserved.

关键词： Manipulators

来源：评论

学校读者我要写书评

暂无评论

Preference-based Evolutionary Many-objective Optimization for Regional Coverage Satellite Constellation Design

Preference-based Evolutionary Many-objective Optimization fo...

引用

作者： Minghui Xiong Wei Xiong Science and Technology on Complex Electronic System Simulation Laboratory Space Engineering University Beijing

For the satellite constellation design problem, the computational complexity of regional coverage performance evaluation has posed great difficulty to classical Pareto dominance-based algorithms discovering the entire Pareto front of the problem, while the decision makers are often interested in a limited part of it. In this paper, a preference-based manyobjective evolutionary algorithm, HMOEA-T, is utilized to solve this problem. The optimization includes two steps. The first step describes the preference information of decision maker by target region, while the second step focuses the search process on the preferred region and maintaining well convergence and diversity within the region. A visualization method is applied to intuitively analysis the performance of different methods handling the problem. Experimental results have shown the advantage of integrating preference information into the optimization process, and the comparative study with other state-of-the-art preferencebased methods(T-MOEA/D and T-NSGA-III) indicate that the proposed method can achieve competitive and better performance.

关键词： evolutoinary algorithm preference articulation constellation design many-objective optimization

来源：评论

学校读者我要写书评

暂无评论

Static simulation scheduling for the validation of space system requirement decomposition

Static simulation scheduling for the validation of space sys...

引用

63rd International Astronautical Congress 2012, IAC 2012

作者： Zhang, Hao Gerndt, Andreas Liu, Bo Simulation and Software Technology Braunschweig Germany Center for Space Science and Applied Research Chinese Academy of Sciences Beijing China Graduate School of Chinese Academy of Sciences Beijing China

ISBN: (纸本)9781622769797

One important issue in space engineering is to ensure that all system requirements arc always fulfilled throughout the whole development process. To perform this task, various validation technologies have been developed. In this paper, document-based reviews and Modelling & simulation technology are illustrated as two of such technology examples. Their disadvantages are analysed as well. The fundamental challenge for them is to carry out a consistent validation throughout the whole development process. To resolve this problem, a static simulation scheduling approach is proposed in this paper. This scheduling approach is based on a hierarchical decomposition model of a space system. The model is constructed following the principles of Model-Based systems Engineering (MBSE). It maps all requirements to state variables and defines states as well as relations along three red lines of a space mission: inter-subsystems, internal subsystems, and space mission lifecycle. In the static simulation scheduling approach, the validation is driven just by the states of state variables and their relations. But, the specific validation process is dependent on current states of the processed variable. The scheduling approach is illustrated and demonstrated in this paper. It facilitates a preliminary validation analysis throughout the whole development lifecycle that would otherwise be cost intensive or even be impossible. Furthermore, after each system refinement, the validation analysis can be performed again automatically. Our work is based on the "Virtual Satellite", which is being developed by German Aerospace center (DLR). We are pursuing the possibility to implement specification, analysis, design, and operation of space missions in a unified framework.©2012 by the International Astronautical Federation.

关键词： Scheduling

来源：评论

学校读者我要写书评

暂无评论

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

请选择保存的检索档案：

请选择收藏分类：

通借通还

建议与咨询 留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

请选择保存的检索档案： 新增检索档案 确定 取消

请选择收藏分类： 新增自定义分类 确定 取消

通借通还

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

请选择保存的检索档案：

请选择收藏分类：