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881.
ALSTOM公司推出了一种名为"e Transformer"的电子变压器,其重量轻、体积小,大大减少了钢材和铜材的使用量. 相似文献
882.
通过超声波探伤,对锻造车轮轮辋上的应力变化进行分析,并将测试值与有限元模拟进行了比较,得出了一致的结果. 相似文献
883.
王志军 《西安交通大学学报(英文版)》1995,(2)
ＤＥＬＡＹＥＤＲＥＰＡＩＲＯＦＤＮＡＤＡＭＡＧＥＢＹＩＯＮＩＺＩＮＧＲＡＤＩＡＴＩＯＮＩＮＰＥＤＩＡＴＲＩＣＳＹＳＴＥＭＩＣＬＵＰＵＳＥＲＹＴＨＥＭＡＴＯＳＵＳＡＮＤＪＵＶＥＮＩＬＥＲＨＥＵＭＡＴＯＩＤＤ．Ｍｃｕｒｄｙ，Ｌ．Ｑ．Ｔａｔ，ＷａｎｇＺｈｉ... 相似文献
884.
介绍「台湾桃园国际机场联外捷运系统建设计划」中机场区段地下工程的设计成果,并探讨施工时将面临的主要工程问题如,潜盾隧道穿越营运中的机场滑行道下方需考虑对其进行保护、隧道遭遇既有地锚的处理方式,及明挖覆盖隧道或车站于卵砾石层进行开挖,临时挡土措施及潜盾隧道的掘进作业,需考虑卵砾石大粒径与高硬度的特性等等设计考虑.现有数据显示,透过适当的机具改良、辅助工法的应用及良好的施工管理,即使是在高地下水压的卵砾石层,施作地下连续壁及以潜盾机施作隧道并无太大困难,且施工引致的地表沉陷及施工精度亦可获得良好的控制. 相似文献
885.
Abstract Walking from origins to transit stops, transferring between transit lines and walking from transit stops to destinations—all add to the burden of transit travel, sometimes to a very large degree. Transfers in particular can be stressful and/or time‐consuming for travellers, discouraging transit use. As such, transit facilities that reduce the burdens of walking, waiting and transferring can substantially increase transit system efficacy and use. In this paper, we argue that transit planning research on transit stops and stations, and transit planning practice frequently lack a clear conceptual framework relating transit waits and transfers with what we know about travel behaviour. Therefore, we draw on the concepts of transfer penalties and value of time in the travel behaviour/economics literature to develop a framework that situates transfer penalties within the total travel generalized costs of a transit trip. For example, value of time is important in relating actual time of waiting and walking to the perceived time of travel. We also draw on research to classify factors most important to users’ perspectives and travel behaviour—transfer costs, time scheduling and five transfer facility attributes: (1) access, (2) connection and reliability, (3) information, (4) amenities, and (5) security and safety. Using this framework, we seek to explicitly relate improvements of transfer stops/stations with components of transfer penalties and changes in travel behaviour (through a reduction in transfer penalties). We conclude that the employment of such a framework can help practitioners better apply the most effective improvements to transit stops and transfer facilities. 相似文献
886.
Since the late 1990s, numerous ridematching programmes have integrated the Internet, mobile phones, and social networking into their services. Online ridematching systems are employing a range of new strategies to create “critical mass”: (1) regional and large employer partnerships, (2) financial incentives, (3) social networking to younger populations, and (4) real-time ridematching services that employ “smartphones” and automated ridematching software. Enhanced casual carpooling approaches, which focus on “meeting places”, are also being explored. Today, ridesharing represents approximately 8–11% of the transportation modal share in Canada and the USA, respectively. There are approximately 638 ridematching programmes in North America. Ridesharing's evolution can be categorized into five phases: (1) World War II car-sharing (or carpooling) clubs; (2) major responses to the 1970s energy crises; (3) early organized ridesharing schemes; (4) reliable ridesharing systems; and (5) technology-enabled ridematching. While ridesharing's future growth and direction are uncertain, the next decade is likely to include greater interoperability among services, technology integration, and stronger policy support. In light of growing concerns about climate change, congestion, and oil dependency, more research is needed to better understand ridesharing's impacts on infrastructure, congestion, and energy/emissions. 相似文献
887.
R. D. Coombe 《运输评论》2013,33(2):165-188
Abstract The recent completion of two major transport studies of predominantly urban areas in the Middle East (Amman‐Jordan and Bahrain) has provided the opportunity to compare and contrast the transport characteristics of, and medium term transport policies for, the two areas. While in structure the two transport systems have many similarities, their base year usage differs significantly. In view of the much lower income levels in Amman, and the resulting lower levels of car ownership, greater reliance is placed on public transport in Amman than in the more car‐oriented society in Bahrain. Against this background, and in the context of broadly similar overall levels of growth in travel demand, their development in the medium term future should follow different paths. Amman will need to depend on public transport very heavily, with only limited road building. Bahrain should be able to develop a satisfactory road system, with public transport playing its current role except for the provision of services for some relatively modest number of restrained private vehicle users. In both cases, however, substantial investment in off‐street parking spaces is needed. The paper briefly describes the social and economic backgrounds of the two areas, and reviews the transport systems and the organisations responsible for them. Travel demand forecasts are summarized, leading to the transport plan and policy development. The prospects for implementation are discussed, and the paper lastly focuses on some aspects which are key to the development of the transport systems in the two countries. 相似文献
888.
In this paper, we present an approach for determining dynamic user equilibria. The method is suitable for disaggregated microscopic and mesoscopic simulation-based models. It is a modification of the convex-simplex method, which disposes with the line search step, and controls the subset of travelers to be re-routed at each step while updating the link travel times after each assignment. To guarantee finite termination, a suitable stopping criterion is adopted. The proposed method is implemented within TRANSIMS, the Transportation Analysis and Simulation System, as a two-stage process that employs a combined use of link performance functions and a microsimulator in order to design a framework suitable for application to real transportation systems. To demonstrate this capability, we apply the developed methodology to a large-scale network, Bignet, which is part of the transportation city network of Portland, Oregon; and a medium-scale network, Blacksburg, Virginia; and provide some comparative analyses. Our results exhibit that an improved distribution of travelers is obtained while consuming less than 17–33% of the effort required by the current version of TRANSIMS. 相似文献
889.
Hanif D. Sherali Jitamitra Desai Hesham Rakha 《Transportation Research Part B: Methodological》2006,40(10):857-871
This paper develops an algorithm for optimally locating Automatic Vehicle Identification tag readers by maximizing the benefit that would accrue from measuring travel times on a transportation network. The problem is formulated as a quadratic 0–1 optimization problem where the objective function parameters represent benefit factors that capture the relevance of measuring travel times as reflected by the demand and travel time variability along specified trips. An optimization approach based on the Reformulation–Linearization Technique coupled with semidefinite programming concepts is designed to solve the formulated reader location problem. To illustrate the proposed methodology, we consider a transportation network that is comprised of freeway segments that might include merge, diverge, weaving, and bottleneck sections. In order to derive benefit factors for the various origin–destination pairs on this network, we employ a simulation package (INTEGRATION) in combination with a composite function, which estimates the travel time variability along a trip that is comprised of links that include any of the four identified sections. The simulation results are actually recorded as generic look-up tables that can be used for any such section for the purpose of computing the associated benefit factor coefficients. Computational results are presented using data pertaining to a freeway section in San Antonio, Texas, as well as synthetic test cases, to demonstrate the effectiveness of the proposed approach, and to study the sensitivity of the quality of the solution to variations in the number of available readers. 相似文献
890.