美国2005年城市机动性报告摘要

美国德克萨斯交通研究所每年发表一份对美国主要城市机动性评估的研究报告。根据2003年和以前的数据,针对美国85个城市区域,2005年的报告对反映其道路系统机动性的主要指标进行了评估,指出美国城市交通阻塞持续恶化。报告列举了交通拥挤引起的一些主要问题,提出了缓解交通紧张状况的一些关键措施,并对这些措施可能产生的效益进行了对比分析。     

普速铁路钢轨服役状态评估方法及应用效果

通过分析国内外换轨周期模式,提出了普速铁路在役钢轨服役状态评估方法和参数,建立了跟踪分析试验段。运用试验段数据统计分析了自上道以来的钢轨伤损与累计通过总质量的关系并掌握了钢轨打磨和使用情况。应用所提出的钢轨服役状态评估方法和参数将试验段原定换轨周期由累计通过总质量7亿t延长到累计通过总质量近10亿t,并分析了换轨周期延长后的经济效益。研究成果为钢轨使用和管理部门延长钢轨使用寿命提供了分析方法和范例。     

Real time prediction of operational safety limits for dynamic positioning of an FPSO in a Deepwater Artificial Seabed system

Aiming to overcome the limitations of conventional offshore field development concepts (dry tree or subsea tree) for petroleum production in ultra-deep water, a new alternative offshore field development solution, termed as Deepwater Artificial Seabed (DAS) system, is proposed. The DAS system works in concert with dynamic positioning (DP) floaters, such as dynamically positioned Floating Production, Storage and Offloading (FPSO) vessels. Rather than relying on the passive mooring system, the DP maintains the reliable position of the FPSO with steering and propulsion units. Nonetheless, critical DP failures, which has potential to cause the drift-off scenario for the FPSO, poses a serious threat to the structural safety of the DAS system. Therefore, it is crucial to establish operational limits for the DP FPSO to prevent such accidents. In this study, a 3-phase probabilistic modelling methodology is proposed to predict safety limits for the operation of the DP FPSO. A surrogate model is established by the Support Vector Machine (SVM) algorithm so as to decrease the computational cost due to the generation of large statistical samples. The statistical distribution of the operational safety limits of FPSO is simulated by the successive approximations through the fully-coupled drift-off analysis. The accuracy of the proposed methodology is verified by a series of mathematical tests. In order to validate the effectiveness of the methodology, the safety limit prediction of the FPSO for the DAS system is taken as a case study. The critical positions of the FPSO are predicted in real time and provides ample time and information for operators’ decision-making by the visualization of the safe moving range of the FPSO. The study contributes to the safety control of DP operations on floating production units in an efficient manner.     

道路运输企业发展甩挂运输的效益研究

甩挂运输是一种先进的运输组织方式,是提高道路运输效率的重要手段,对于促进节能减排,推动道路运输业的发展具有重要意义。本文针对某一具体甩挂运输企业构建数学模型并从固定成本、变动成本两个方面对其进行经济效益评价,从油耗、二氧化碳排放量和污染物排放量三个方面进行节能减排评价,进而论证得出了甩挂运输具有提高经济效益和节能减排的优势。     

Predicting the operational acceptance of airborne flight reroute requests using data mining

For tools that generate more efficient flight routes or reroute advisories, it is important to ensure compatibility of automation and autonomy decisions with human objectives so as to ensure acceptability by the human operators. In this paper, the authors developed a proof of concept predictor of operational acceptability for route changes during a flight. Such a capability could have applications in automation tools that identify more efficient routes around airspace impacted by weather or congestion and that better meet airline preferences. The predictor is based on applying data mining techniques, including logistic regression, a decision tree, a support vector machine, a random forest and Adaptive Boost, to historical flight plan amendment data reported during operations and field experiments. Cross validation was used for model development, while nested cross validation was used to validate the models. The model found to have the best performance in predicting air traffic controller acceptance or rejection of a route change, using the available data from Fort Worth Air Traffic Control Center and its adjacent Centers, was the random forest, with an F-score of 0.77. This result indicates that the operational acceptance of reroute requests does indeed have some level of predictability, and that, with suitable data, models can be trained to predict the operational acceptability of reroute requests. Such models may ultimately be used to inform route selection by decision support tools, contributing to the development of increasingly autonomous systems that are capable of routing aircraft with less human input than is currently the case.     

Potential Benefits of Coastal Ocean Observing Systems to Alaskan Commercial Fisheries

In this article we attempt to illustrate the potential benefits to Alaskan commercial fisheries expected from enhancements to the Alaska Ocean Observing System (AOOS) through changes in fishery management strategies. In particular we show how the use of improved AOOS data in research, stock assessment, and ultimately fisheries management has the potential to result in significant benefits in the Bering Sea and Gulf of Alaska groundfish and Kodiak king crab fisheries. We show through a case study approach that information such as might be provided by an enhanced AOOS could conceivably contribute over $600 million in additional annual revenue in Alaska's groundfish fishery. In addition we estimate that had the information from such a system been available in the 1970s and 1980s the Kodiak king crab stock collapse could have been avoided and $60 million in annual revenues generated. Benefit estimates (as measured by revenue increases) are based on the assumptions that when better data is delivered those data will be integrated into stock assessment models; when better data are integrated into the models the new data will actually improve the reliability of the models; and when the reliability of the models is improved predictions will be accepted by managers or industry members.     

列车交会压力波与运行速度的关系

随着列车速度的提高,列车交会时产生的瞬态压力冲击对行车安全、旅客舒适性均产生严重影响。根据多次实车试验结果和理论分析,将列车交会分为列车静止交会、等速交会和不等速交会3种工况,研究了3种工况的列车交会压力波与运行速度之间的关系,得到一系列回归关系式。研究结果表明:静止列车上的压力波与交会列车运行速度的平方成正比;两列车等速交会时,列车上的压力波幅值与两交会列车的运行速度和相对速度的平方成正比;两列车不等速交会时,高速列车承受的压力波幅值小于与之交会的低速列车所承受的压力波幅值;两列车等速交会时的压力波大于一方列车静止时交会的压力波。     

石家庄地铁一期运营的社会经济效益研究

本文基于建设项目的费用与效益的识别原则以及有无对比法的思路,分析社会经济效益的构成。以石家庄市地铁1、3号线一期工程为蓝本,从受益者的角度将社会经济效益从轨道交通的建设者、轨道交通的使用者以及社会生态环境等方面系统地阐述城轨交通的建设给城市带来的外部效益。基于以往社会效益量化模型,对石家庄地铁的社会效益进行量化分析,并对其中可量化的效益给出计量模型,最后对石家庄轨道交通一期运营的社会经济效益进行估算。     

Application of perceived value model to identify factors affecting passengers' repurchase intentions on city bus: A case of the Taipei metropolitan area

This paper establishes and tests the perceived value model, which is applied to identify the factors affecting the passengers' repurchase intentions on city bus. In this study, perceived value is a trade-off between perceived benefits and perceived costs. And the main part of perceived benefits is service quality. We (1) measured service quality using a multiple-items scale, (2) integrated perceived non-monetary price as a part of perceived costs, and (3) simultaneously incorporated the attractiveness of alternative modes. Data was collected via a questionnaire survey in the Taipei metropolitan area and the model was tested using path analysis performed by LISREL. The results indicate that all causal relationships are statistical significant. Finally, this study concludes by discussing managerial implications and making suggestions for future research.     

浅谈水泥混凝土路面修复设计

水泥混凝土路面的修复整治已经成为广大市政建设工作者关注和研究的—个重要课题。在水泥混凝土路面上做沥青加铺层,具有“刚柔相济”的特点,路基强度高,稳定性好,路面平整、无接缝,行车舒适,能够大大改善旧路面的使用性能。