Recognizing metro-bus transfers from smart card data

Transfer points between metro and bus services remain an elusive, yet critical junction for transportation practitioners. Based on massive Smart Card (SC) data, previous studies apply a one-size-fits-all criterion to discriminate between transfers. However, this is not sufficiently convincing for different transfer pairs. To counter this problem, this study applies an association rules algorithm and cluster analysis to recognize metro-to-bus transfers using SC data, and demonstrates transfer recognition in a case study based on SC data collected during a week in Nanjing, China. It is shown that 85% of the transfer-recognition results are quite stable through the whole week, and the median transfer time between metro and bus is below 20?min. The method proposed in this study can be used to identify the busiest transfer points and to obtain average transfer times, which facilitates a smarter and more efficient public transit network.     

内河航道LNG动力船冷能综合梯级利用设计及分析

针对内河航道LNG动力船发电、冷库和空调需求,对于LNG在气化过程进行冷能梯级利用方案设计,并进行能量分析和[火用]分析.研究结果表明,与直接在环境中气化相比,采用LNG冷能回收,并应用于冷能发电系统、船舶冷库系统、船舶空调系统和缸套冷却水系统,实现了LNG动力船冷能梯级利用.在冷能利用过程中,冷能发电和船舶冷库回收的冷能较大,冷能发电系统[火用]值较高,可有效调节船舶冷库的冷量.     

Priority based data reporting algorithm in wireless sensor networks

A cluster-based organization with two phases to separate priority calculation and network activity operations is developed. In the election-state phase, clusters are organized by those nodes with sufficient residual energy level (REL) that are distributed as evenly as possible in the network. For each network round, each node decides its role (such as, cluster header (CH) or a normal node) and its priority level for activity operation. The priority level also affects the active/sleep scheduling in the node. In the steady-state phase, the positive priority levels of active nodes determine their activity order to avoid transmission collision, and to reduce redundant data transmission and sensing coverage. Since the data reporting to the sink is usually performed by a CH delivery chain, subsidiary CHs are selected to assist with data delivery and to share the loading of CHs. The formulae for computing priority levels are analyzed and verified by the examples with valid parameters. The experimental results show that the two phases efficiently consume node energy and achieve energy savings.     

5万吨级灵便型散货船设计及船型研究

介绍了5万吨级灵便型散货船在国际航运市场的需求情况和该船的主尺度分析、船体设计以及航运经济性等。重点介绍了船体线型优化设计;设计两个球首和两个球尾线型,形成三个船型方案,通过船模试验结果,分析比较了首尾线型变化对船舶快速性各项因子的影响。与国际上同类船航运经济性比较结果证明,该船型快速性指标先进,设计合理,是经济高效的船舶。     

采用三叉树空间分割算法提高集装箱积载率

三叉树算法利用空间分割技术,旨在通过计算机仿真技术模拟实际的集装箱装载过程。根据商品实体的三叉树模型之间的几何关系,按一个特定的准则划分仿真空间,从而直接确定模型中节点之间的位置关系。运用以这项技术为核心的储运软件可以大大提高集装箱积载率,降低运轮面本。     

基于库仓理论的非饱和膨胀土主动土压力计算

分析了非饱和膨胀土的强度特性,以库仓土压力理论为基础,考虑非饱和膨胀土基质吸力,推得了挡土墙极值条件下的主动土压力公式,该公式无须试算可直接求出主动土压力和填土滑裂面与水平面的夹角。公式计算简便,便于工程技术人员掌握和应用。     

真空深井降低浅埋微型隧道地下水位试验研究

在深井中设计了真空泵,有效地把渗透系数小于0.1 m/d的土层的高地下水位降低至地表15 m以下。真空深井降水设计计算可按深井降水计算,只有井距调整为最初计算值的60%,井深比最初计算值增大2~3 m,其余参数相同;真空降水井真空度宜为0.04~0.06 MPa;可通过调整花管长度、增大井管的密封程度、实施不同的开挖工序来保证井管及井管周围土体的真空度。     

浅谈混凝土的施工温度与裂缝

介绍混凝土温度裂缝产生的原因、温度应力和预防裂缝的措施等,可供同类工程参考。     

土工合成材料在路基加宽中的作用影响数值分析

利用有限元数值计算方法,对在软土地基上利用土工合成材料加宽的路基结构进行了分析,研究了软基厚度、路堤高度和路堤加宽值等对加筋效果的影响。计算结果表明,对应给定的路基高度、路基加宽值,当软土层厚度不大于某一临界值时,可以铺设具有合适抗拉刚度和抗拉强度的筋材,来达到控制新旧路基的不均匀沉降。     

压差调节器静态特性试验研究

通过试验对压差调节器进行了整定,获得了它的静态特性曲线,结果表明压差调节器的性能可以满足要求.