Application of El Farol model for managing marine terminal gate congestion

Truck queuing at marine terminal gates has long been recognized as a source of emissions problem due to the large number of trucks idling. For this reason, there is a great deal of interest among the different stakeholders to lessen the severity of the problem. An approach being experimented by some terminals to reduce truck queuing at the terminal is to provide live views of their gates via webcams. An assumption made by the terminals in this method is that truck dispatchers and drivers will make rational decisions regarding their departure times such that there will be less fluctuations in truck arrivals at the terminal based on the live information. However, it is clear that if dispatchers send trucks to the terminal whenever the truck queues are short and not send trucks when the truck queues are long, it could lead to a perpetual whip lash effect. This study explores the predictive strategies that need to be made by the various dispatchers to achieve the desired effects (i.e. steady arrival of trucks and hence less queuing at the seaport terminal gates). This problem is studied with the use of an agent-based simulation model and the solution to the well known El Farol Bar problem. Results demonstrate that truck depots can manage (without any collaboration with one another) to minimize congestion at seaport terminal gates by using the provided real-time gate congestion information and some simple logics for estimating the expected truck wait time.     

麦克纳姆轮技术及其在船用轮式设备中的应用

介绍了麦克纳姆轮结构及其全方位运动原理.针对麦克纳姆轮结构的不足与全方位车辆的船用化需求,改进了麦克纳姆轮结构、设计了铰接式车架、传动系统及驱动方案.实践证明,在此基础上研制的全方位叉车及全方位转运车能很好地在空间狭小的船舶环境中灵活运转.     

Information Presentation of Coastal Morphological Change: Potential Implications for Perceptions of Climate Change Impacts

Visual imagery of costal morphological change processes must be accompanied by supporting information to make change processes understandable. We explored the influence of supporting information (graphs and numeric values) on perceptions of coastal morphological change processes through an experiment delivered to coastal recreationists. Supporting information was presented alongside four imagery types: human perspective digital elevation models (DEMs), human perspective digital photographs, aerial views of DEMs and aerial photography. We found neither the use of graphs nor numeric values influenced respondents' perceptions of coastal environmental change. However, perceptions varied significantly across imagery type; human perspective digital photographs and aerial photographs yielded higher ratings compared to human perspective DEMs and aerial views of DEMs. The results suggest supporting information representing increasingly severe rates of beach erosion and shoreline movement does not translate into perceptions of increasingly dramatic geophysical processes; this is consistent with previous empirical findings. The results also suggest individuals perceive coastal change processes as more severe when those processes are presented through photographs, particularly aerial photographs. Scientists, educators and coastal land use managers struggling to communicate the magnitude and severity associated with coastal geophysical processes are advised to use comparative aerial photography when possible.     

配筋混凝土箱梁长期受力性能的比拟杆分析

为使配筋混凝土箱梁长期受力性能的分析趋于简便,将线弹性匀质箱梁短期弯曲性能分析的比拟杆法推广应用于其长期受力性能的分析。引入按龄期调整的有效弹性模量来考虑箱梁混凝土徐变的影响,基于换算截面的原理来考虑箱梁配筋的影响,建立能综合考虑箱梁受力特征和配筋影响的混凝土箱梁长期受力性能分析的比拟杆法。对一根预应力混凝土模型箱梁进行长达1001d的徐变试验,并用其结果对所提方法的适用性进行验证。结果表明:混凝土箱梁长期受力性能的比拟杆法计算结果与试验结果之间吻合较好。与试验值相比,t0～1001d时段内箱梁顶板混凝土压应变的计算值相差7%～11%、跨中截面长期挠曲变形的计算结果相差9%～17%。随着持荷时间的增长,箱梁顶板的剪力滞系数逐渐减小,持荷1001d后剪力滞系数减小了7.1%。     

底面外贴钢筋加固混凝土梁抗弯性能试验研究

通过1根控制试验梁与5根加固梁的静力试验,对底面外贴钢筋加固混凝土梁的抗弯性能进行试验研究.讨论加固试验梁在不同加固技术参数下(增补钢筋面积、锚栓布置与数量)的裂缝开展、刚度变化和承载力提高等情况,并分析各参数因素对试验梁加固的影响规律.试验结果表明:底面外贴钢筋加固试验梁经加固后其开裂荷载、刚度和抗弯承载力均显著提高;从跨中截面的混凝土应变规律可知,正截面应变符合平截面假定.提出外贴钢筋加固混凝土梁正截面抗弯承载力计算公式,由该公式计算的正截面承载力计算值与试验值吻合良好.     

桥梁扩大基础施工实例

桥梁基础施工质量的好坏直接关系到桥梁整体的安全性。结合工程实例,针对基坑开挖、基底处理、基础钢筋绑扎以及基础混凝土浇筑等环节,提出桥梁扩大基础施工的技术控制措施,为同类工程提供参考借鉴。     

钢筋剥肋滚轧直螺纹连接工艺在大直径桩基中的应用

湘潭湘江四大桥桩基钢筋笼施工中,采用了钢筋剥肋滚轧直螺纹连接工艺,提高工作效率、工程质量和节约施工成本,并积累了施工经验。     

大型建(构)筑物整体移位技术在高铁建设中的应用

建筑物移位是指通过一定的工程技术手段,在保持建筑物整体性的条件下,改变建筑物的空间位置,包括平移、旋转、抬升、迫降等单项移位或组合移位。建筑物整体移位技术20世纪80年代传入我国。近年来,随着我国城市建设的大规模开展,此项技术得到了迅速发展,尤其是近十年来,随着PLC同步控制技术的应用,发展至今已趋于成熟。将这一技术发展至大型梁体的整体移位,进而应用到高铁建设中,可缩短工期,降低成本。     

Control of semi-active anti-roll systems on heavy vehicles

Semi-active anti-roll systems, with a high and low roll stiffness, or, since cornering is typically a transient event, damping setting have the capacity to improve heavy vehicle stability while having very low power consumption. If a vehicle is travelling around a right-hand bend and a low roll damping setting is selected, the vehicle will roll outwards. If a high damping setting is then selected, the outward roll will be locked-in. When the vehicle enters a left-hand bend, the inward roll becomes locked-in. This has the potential to increase critical lateral acceleration by up to 12.5% if the vehicle's future course can be predicted accurately (e.g. with a Global Positioning System). However, if the vehicle does not follow the expected path, the critical lateral acceleration may be degraded. Exploiting the delay between a steer angle being applied and the lateral acceleration developing could avoid this problem. However, the benefits from such a system are considerably lower, up to a 2.4% improvement in critical lateral acceleration. Hence, a ‘modal control strategy’ is developed aimed at providing high levels of benefit while being robust to deviations from the expected path. The modal strategy is able to provide benefits of up to 11%, while being robust to most deviations.     

火车站综合交通客运枢纽客流与设施容量预测分析

科学的客流预测是合理布置交通设施的重要基础。通过分析火车站综合交通客运枢纽客流构成,提出客流预测的总体思路和框架,并对客流预测的常用方法加以介绍,最后总结相应的设施容量计算方法,这为火车站客流预测提供了一种新的思路,值得推广。