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Journal of Mathematical Research with Applications 2012年第4期32卷 399-406页

作者： Shengxiang L1, , Yanpei LIU 2 1. Department of Mathematics, Hunan university of Science and Technology, Hunan 411201, P. R. china 2. Department of Mathematics, beijing jiaotong university, beijing 100044, P. R. china. Department of Mathematics Hunan University of Science and Technology Hunan 411201 Department of Mathematics Beijing Jiaotong University Beijing 100044

Let G be a k(k ≤3)-edge connected simple graph with minimal degree ≥ 3,girth g,r=*** any independent set {a1,a2 , . . . , a 6/(4 k)} of G,if,then G is up-embeddable.

关键词： up-embeddability maximum genus independent set

Study on fracture behavior of SiCp/A356 composites

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Rare Metals 2006年第Z2期25卷 168-173页

作者： KANG Suk-Bong Department of Materials Engineering Korean Institute of Machinery & Materials Gyeongnam 641831 Korea

The fracture behavior of SiCp/A356 composite at room and high temperatures was studied. Under tensile stress condition at room temperature, the fracture is mostly a combination of the brittle fracture of SiC particles and ductile fracture of A356 matrix. As the tensile temperature increases, the composite changes the main fracture behavior to the separation fracture of the bonding surface between SiC particles and A356 matrix. When the tensile temperature reaches 573 K, the fracture behavior of the composites is almost the whole separation fracture of the bonding surface, which is the main strengthening mechanism at high temperature. Under the cycle stress condition at room and high temperatures, the main fracture behavior of the composites is always a combination of the brittle fracture of SiC particles and ductile fracture of A356 matrix. However, under the cycle stress at high temperature, cycle behavior of the composites changes from cycle hardening at room temperature to the cycle softening at high temperature.

关键词： SiCp/A356 composites brittle fracture ductile fracture separation fracture

Dynamic traffic Assignment and Signal Control in Saturated Road Networks

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Dynamic Traffic Assignment and Signal Control in Saturated R...

A Fuzzy Logic-Based Framework for Route Choice in Vehicle Navigation Systems

2005全国博士生学术论坛（交通运输工程学科）

作者： Lian Aiping, Ren Hualing, Gao Ziyou (school of traffic and transportation, beijing jiaotong university, beijing 100044)

＜正＞ This paper presents a generalized bi- level programming model fcr dynamic traffic assignment and traffic signal central in saturated road networks, and especially analyzes a procedure for determining the equilibrium queuing delays on saturated links for dynamic network signal control satisfying the FIFO （Fust -In-First -Out） rule. The genetic algorithm （GA） proposed in this paper can not only present the optimal signal settings, but also calculate, at each interval, the link inflow rates, the link outflow rates for the dynamic user optimal problem, and provide the real-time information for the travelers. Finally, a numerical example is given to illustrate the applications of the proposed model and solution algorithm, and comparison shows that this model has better system performance.

关键词： dynamic user optimal traffic optimal signal setting genetic algorithm

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Systems Science and Systems Engineering 2000年第4期10卷 467-474页

作者： YANG Qun,\ ZHAO Ya\|nanITS research center, Northern jiaotong university, beijing 100044, china

Vehicle Navigation Systems (VNS) is an important component of Intelligent transportation Systems (ITS). These Systems are designed to assist drivers in making pre trip and enroute travel choice decisions, and typically, they must provide route choice, route guidance and other related services. Although there have been a lot of existed systems in the market, and most of them used lots of contemporary technologies, they are believed short of ″true intelligence″, because they paid little attention to the subjective issues in driver′s route choice behavior, such as travel objectives and personal preferences, etc. \;However, the VNS is designed for its users, and the successful implementation of VNS is largely dependent on the driver′s acceptance. If the driver feels that the VNS can′t give him (her) a satisfactory choice, he (she) will not use it, then, the marketing value of VNS will decline. And on the whole, the transport benefit that is mainly gained by the wide use of ITS will lost. \;Supported by the research project of ″beijing Intelligent Urban transportation Systems″, this paper presents a conceptual model to deal with this problem. We first defined the driver′s objective as a linguistic statement that has a set of attributes. These attributes are then treated as the fuzzy sets on the universal of all the existed routes. By determining each attribute′s membership function and assign driver dependent perception to these attributes, we can change the multi criteria route choice problem into a fuzzy logic based decision making problem. Then, to meet the demands of dynamic real time route selection, we use a limited routes set for choice and can swiftly get a satisfactory solution that we think is the driver′s actually needs.

关键词： vehicle navigation systems intelligent transportation systems fuzzy logic

Research on Railway Refrigerated transportation Development

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Research on Railway Refrigerated Transportation Development

The Pattern of Rhythm in King Lear

2005全国博士生学术论坛（交通运输工程学科）

作者： Hai Tao, Wang Lingli, Zhang Xingchen (school of traffic and transportation beijing jiaotong university, beijing 100044)

＜正＞ The paper firstly analyzes the changes in the perishable goods transportation market, such as producing area enlarged, production and transportation volume increased, goods flow direction decentralized, transportation batch diminished, trade individualized, the quality and time efficiency became more important, etc.. Afterward it introduces the situation of railway perishable goods transportation, including the achievement and problems, and analyzes the deep reasons of the volume decline form the aspects of management idea, price policy, finance, transportation organization and facilities and so on. then, it give some measures to improve the railway refrigerated transportation, such as the reform of the management institution, transportation organization strengthening, new product developing, technology management and basic theory study, transportation vehicle melioration and auxiliary facilities ability enlarging. Lastly, the paper makes a case study with the refrigerated transportation competition between railway and highway from Guangzhou to beijing.

关键词： refrigerated transportation perishable goods transportation organization

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兰州大学学报（社会科学版） 2000年第S1期28卷 114-119页

作者： Bai Yanlei Ji Yushan (Foreign Languages Department, College of Humanities, Northern jiaotong university, beijing, 100044 Section of Fundamental Education, china Armed Police school, Langfang, 102800, china)

This paper studied Shakespeare’s King Lear from the perspective of rhythmits implications, its patterns and its realization.

关键词： Shakespeare King Lear rhythm

Optimization of Processing Parameters for Laser Powder Deposition using Finite Element Method

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Journal of Wuhan university of Technology(Materials Science) 2010年第5期25卷 832-837页

作者：付垚 State Key Laboratory of Non-ferrous Metals and Processes General Research Institute for Non-ferrous Metals

In order to investigate the effects of powder materials and processing parameters on thermal and stress field during laser powder deposition （LPD）, a finite element model was developed with the help of ANSYS software. The finite element model was verified by the comparison between the experimental results and computed results. Then LPD processes with different powder materials and processing parameters were simulated by using the FE model. The results show that less difference of thermal conductivity and thermal expansion coefficient between powder material and substrate material produces lower residual stress; higher laser power, laser scanning speed and smaller laser beam diameter can lead higher peak temperature and higher residual stress. The research opens up a way to rational selection of the powder materials and processing parameters for ensured quality.

关键词： laser powder deposition thermal field stress field powder material processing parameters

Optimal motion planning of an underactuated spacecraft using wavelet approximate method

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Progress in Natural Science:Materials International 2006年第8期16卷 868-873页

作者： GE Xinsheng, CHEN Liqun and LIU Yanzhu (beijing Institute of Machinery, beijing 100085, china Department of Mechanics, Shanghai university, Shanghai 200072, china Department of Engineering Mechanics, Shanghai jiaotong university, Shanghai 200030, china) beijing Institute of Machinery Beijing 100085 China Department of Mechanics Shanghai University Shanghai 200072 China Department ofEngineering Mechanics Shanghsi Jiaotong University Shanghsi 200030 China

An optimal motion planning scheme using wavelet approximation is proposed for an underactuated spacecraft. The motion planning of an underactuated spacecraft can be formulated as an optimal control of a drift-free system. A cost functional is used to incorporate the control energy and the final state errors. The motion planning is to determine control inputs to minimize the cost functional. Using the method of wavelet, one can transform an infinite-dimensional optimal control problem to a finite-dimensional one and use Gauss-Newton algorithm to solve it for a feasible trajectory which satisfies nonholonomic constraints. The proposed scheme has been applied to a rigid spacecraft with two momentum wheels. The numerical simulation results indicate that optimal control with wavelet approximation is an effective approach to steering an underactuated spacecraft system from the initial configuration to the final configuration.

关键词： underactuated spacecraft motion planning optimal control nonholonomic constraint wavelet analysis.

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考虑交通出行惯例的双向行人流模型研究

物理学报 2011年第10期60卷 42-49页

作者：杨凌霄赵小梅高自友郑建风北京交通大学交通运输学院北京100044 北京交通大学城市交通复杂系统理论与技术教育部重点实验室北京100044

推广了Baek等人最近提出的一个双向行人流模型,提出了两种改进策略,并从行人平均速度-密度关系、行人空间分布密度和位置分布等方面进行了数值分析.研究发现,引入的两个新策略不仅可以提高行人流的平均速度,而且可以提高道路系统(尤其... 详细信息

推广了Baek等人最近提出的一个双向行人流模型,提出了两种改进策略,并从行人平均速度-密度关系、行人空间分布密度和位置分布等方面进行了数值分析.研究发现,引入的两个新策略不仅可以提高行人流的平均速度,而且可以提高道路系统(尤其是道路中央区域)利用率,减轻拥堵状况,有效避免严重堵塞的发生.改进的策略对行人的心理特点和行为特性等方面考虑更加全面,而且可以较好地模拟高密度的双向行人流.

关键词：元胞自动机模型双向行人流交通惯例