首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   76篇
  免费   4篇
公路运输   15篇
综合类   22篇
水路运输   27篇
铁路运输   7篇
综合运输   9篇
  2023年   1篇
  2022年   3篇
  2021年   1篇
  2020年   2篇
  2019年   1篇
  2018年   2篇
  2017年   2篇
  2016年   3篇
  2015年   6篇
  2014年   5篇
  2013年   6篇
  2012年   7篇
  2011年   8篇
  2010年   7篇
  2009年   10篇
  2008年   6篇
  2007年   6篇
  2005年   2篇
  2004年   1篇
  1998年   1篇
排序方式: 共有80条查询结果,搜索用时 781 毫秒
61.
美反潜无人艇作战使用分析   总被引:1,自引:0,他引:1  
美国军用UUV处于世界领先水平,ACTUV是UUV的一种。ACTUV是一种具有特色的水下作战力量。介绍了ACTUV的基本性能与特点,对其作战使用进行了分析。  相似文献   
62.
结合保障需求实际情况,对比M/M/c/∞/∞排队模型和多个M/M/1/∞/∞排队模型所需的平均保障时间,得出科学规划部署保障力量的决策参考,并给出了算法实现要点。  相似文献   
63.
Technological paradigm shifts often come with a newly emerging industry that seeks a viable infrastructure deployment plan to compete against established competitors. Such phenomenon has been repeatedly seen in the field of transportation systems, such as those related to the booming bioenergy production, among others. We develop a game-theoretic modeling framework using a continuum approximation scheme to address the impacts of competition on the optimal infrastructure deployment. Furthermore, we extend the model to incorporate uncertainties in supply/demand and the risk of facility disruptions. Analytical properties of the optimal infrastructure system are obtained, based on which fast numerical solution algorithms are developed. Several hypothetical problem instances are used to illustrate the effectiveness of the proposed algorithms and to quantify the impacts of various system parameters. A large-scale biofuel industry case study for the U.S. Midwest is conducted to obtain additional managerial insights.  相似文献   
64.
结合太行山隧道进口工程施工,介绍高动力、高压电力设备的合理选型配置和注意事项。通过实践,达到了预期的技术目标和要求,既保证了隧道的安全、优质、高效施工,又节约了隧道施工成本。  相似文献   
65.
A numerical approach was developed to analyze the transient behavior of towed cable during ac- tively controlled deployment/retrieval (DR). The cable motion is described by the lumped parameter method, its corresponding boundary conditions are presented. In view of its varying length during DR, two auxiliary arguments are introduced to describe its continuous varying length and discrete number of nodes(equations), the length is determined by the pay out(or reel-in) rate, which is then used to determine the node number by a logic relation. For the discrete mathematical model of towed cable, an algorithm was developed to deal with the discrete governing equations. The simulation results indicate that the cable experiences more com- plex motions due to its varying length, and tension fluctuates seriously in the startup and ending stage of deployment/retrieval. The effect of towing ship's motion in waves on cable during deployment/retrieval is also considered via numerical simulation.  相似文献   
66.
Hazardous materials routing constitutes a critical decision in mitigating the associated transportation risk. This paper presents a decision support system for assessing alternative distribution routes in terms of travel time, risk and evacuation implications while coordinating the emergency response deployment decisions with the hazardous materials routes. The proposed system provides the following functionalities: (i) determination of alternative non-dominated hazardous materials distribution routes in terms of cost and risk minimization, (ii) specification of the hazardous materials first-response emergency service units locations in order to achieve timely response to an accident, and (iii) determination of evacuation paths from the impacted area to designated shelters and estimation of the associated evacuation time. The proposed system has been implemented, used and evaluated for assessing alternative hazardous materials routing decisions within the heavily industrialized area of Thriasion Pedion of Attica, Greece. The implementation of the aforementioned functionalities is based on two new integer programming models for the hazardous materials routing and the emergency response units location problems, respectively. A simplified version of the routing model is solved by an existing heuristic algorithm developed by the authors. A new Lagrangean relaxation heuristic algorithm has been developed for solving the emergency response units location problem. The focus of this paper is on the exposition of the proposed decision support system components and functionalities. Special emphasis is placed on the presentation of the two new mathematical models and the new solution method for the location model.  相似文献   
67.
Tactical planning models for liner shipping problems such as network design and fleet deployment usually minimize the total cost or maximize the total profit subject to constraints including ship availability, service frequency, ship capacity, and transshipment. Most models in the literature do not consider slot-purchasing, multi-type containers, empty container repositioning, or ship repositioning, and they formulate the numbers of containers to transport as continuous variables. This paper develops a mixed-integer linear programming model that captures all these elements. It further examines from the theoretical point of view the additional computational burden introduced by incorporating these elements in the planning model. Extensive numerical experiments are conducted to evaluate the effects of the elements on tactical planning decisions. Results demonstrate that slot-purchasing and empty container repositioning have the largest impact on tactical planning decisions and relaxing the numbers of containers as continuous variables has little impact on the decisions.  相似文献   
68.
通过对铁路项目材料运杂费计算的论述,分析说明存在的实际问题。结合工作实践,针对材料运距计算模型、过程及参数确定等问题进行探讨分析,提出利用"二次平均法"计算材料平均运距具有相对优势,可以进一步推广应用。  相似文献   
69.
本文在分析铁路防灾系统架构和特点的基础上,使用无线传感器网络(WSN) 技术对现有系统进行无线化改进.充分发挥WSN的优点,采用Zigbee 和RFID技术,设计 基于WSN的铁路防灾系统架构、组网方案和数据传输方案.在现有防灾监控系统功能的 基础上,新增车地传输功能,将列车运行前方的环境情况发送给列车,为列车运行提供参 考.此外,详细研究Zigbee节点和RFID节点的部署方案,并对节点部署情况进行仿真及实 例分析.本系统能够降低防灾系统的安装难度和部署成本,并为列车实时提供前方运行环 境情况,为高速列车的安全运行提供保障.  相似文献   
70.
根据土石方工程施工面广、施工条件复杂等特点,分析了土石方工程施工机械的配置原则、选配方法,以挖掘机、自卸汽车为例,详细论述了其配置过程与配置算法,可帮助工程技术人员确定合理的机械配置,从而降低施工成本,加快施工进度。  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号