Mixed RP/SP models incorporating interaction effects

In order to analyse the impact of a new train service in Cagliari (Italy) a databank including information from a revealed preference (RP) and a stated preference (SP) survey was set up. The RP data concern choice between car, bus and train; the SP data consider the binary choice between a new train service (quicker, more frequent, with a lower fare and more stations than the current one) and the alternative currently chosen by car and bus users. Logit models allowing for correlation among RP alternatives were estimated for this mixed RP/SP data set using the artificial tree structure method. The analysis included level-of-service variables measured with an unusually high level of precision, latent or second order variables (such as comfort), inertia and interaction variables. Different specifications of the utility function were tested, including the expenditure rate model, and the effects of these specifications on modelling results are highlighted. Our results show that for a population mainly composed of fixed income workers, the expenditure rate model is superior to the traditional wage rate model, yielding lower and more significant subjective values of time. Moreover, we found that the non-linear specifications appear to be more suitable as not only better model results were obtained, but also the real distribution of the error terms was revealed (i.e. highlighting correlation among public transport options).     

庄河港疏港铁路接轨方案研究

庄河港区是大连港的重要组成部分,是庄河市建设＂新大连＂战略实施的重要保障,是庄河临港工业区和花园口经济区临港工业发展的重要依托。通过研究庄河西接轨方案、兰店接轨方案的优缺点,最终确定庄河西接轨方案作为贯通方案。     

南京地铁AFC区域线路中心的规划设计

在介绍南京地铁AFC系统建设现状的基础上,给出区域线路中心的概念,分析建设区域线路中心的必要性,阐述区域线路中心的关键问题,介绍南京地铁AFC系统区域线路规划设计情况,最后对南京地铁AFC区域线路中心仍待解决的问题进行分析和展望。     

基于SOPC技术的MVB网卡在分布式车载故障检测记录系统中的应用

针对现有分布式车载故障检测记录系统所用控制器局域网(CAN)不适合用作车辆总线的情况,提出采用多功能车辆总线(MVB)的方案.详细阐述了系统结构改造及工作原理转换等关键设计理念,设计了一种基于SOPC(可编程片上系统)技术的多功能接口MVB网卡,给出其软硬件实现方案,最终在实验室进行组网测试,验证了设计的正确性和可行性.改造后的系统网络传输距离更远、速率更高,并且具有较好的实时性和可靠性.     

基底脱空条件下铁路隧道行车安全性分析

结合大瑶山隧道基底病害,在混凝土塑性损伤本构模型基础上,建立隧道-围岩相互作用动力计算模型,研究基底脱空对铁路隧道行车安全的影响。结果表明:随隧道基底脱空距离增加,隧道底部结构动力响应和损伤增大,且脱空距离超过一定深度后变化加剧;对于内侧单边脱空、两侧对称脱空和中间扩展脱空方式,当脱空距离分别达60、60、180cm时,需采取限速、加固等措施保证隧道行车安全。各脱空方式中,以两端向中间脱空方式所受影响最大。在该脱空方式下,当脱空距离从0cm增加到90cm时,底部结构竖向位移最大增幅达1.5倍;加速度最大增幅达17.2倍;主应力最大增幅达3.2倍;损伤值最大增幅达1.4倍。当脱空距离达120cm时,底部结构已发生破坏。可见,基底脱空对结构稳定和受力极为不利,将加剧结构损伤破坏。研究结果可为铁路隧道行车安全性评价和基底脱空整治提供参考。     

基于联合介数中心度的铁路货运嵌入社会大物流系统网络结构优化

社会大物流系统是一个无标度网络,存在明显的集群现象.铁路货运系统作为另一个群体嵌入社会大物流系统,需要在优化网络结构的同时,考虑群体之间的连接和群体内部的连接.基于Barabási-Albert算法的无标度网络生成机制,通过理论推导和实验仿真,分析联合介数中心度及其标准差与网络货流量的关系.研究认为,铁路货运系统节点嵌入社会大物流系统时,应当选择联合介数中心度较大而其标准差较小的节点进行嵌入,通过增加捷径路径可改善中枢节点的连接性,以及减轻和均衡中枢节点的负荷,使得整个物流系统更高效地运作和降低网络优化的成本.     

机车用JC120型高摩擦系数合成闸片运用报告

自主研发机车用JC120型高摩擦系数合成闸片,该型闸片经23t轴重及25t轴重机车运行试验,结果达到机车设计任务书的要求,装车运行试验约22万km拆检制动盘及闸片表面状态良好,磨耗很少,但随运行工况的变化及运行里程的延长,也相继存在少许金属镶嵌、盘面黑斑等缺陷,经进一步改进、提高,这些问题都得到圆满解决.现该闸片已经装车运行50万km,并经过两次提速货车120 km/h可靠性试验考验,证明能够满足120 km/h级交流传动电力机车的制动要求,能保证行车的安全性.     

2Cr13钢转动座热处理工艺优化试验研究

2Cr13钢转动座耐腐蚀性能受其热处理工艺影响较大,分析尾轴密封装置转动座腐蚀失效的原因,优化2Cr13钢转动座热处理工艺,成为一项迫切的任务。通过反复试验,全面测试了2Cr13钢转动座物理机械性能和耐蚀性能与热处理的关系,分析了2Cr13钢在不同回火温度中随析出相不同,其物理机械性能和抗腐蚀能力的变化规律。研究结果表明,2Cr13钢在低温回火时,材料的综合性能强,可同时保证硬度、强度、耐磨性及耐腐蚀性能的要求。     

Seasonal changes in wildlife use of motorway crossing structures and their implication for monitoring programmes

Multiple factors determine the use and effectiveness of wildlife passages and crossings installed in new roads as mitigation measures against the barrier effect. It is unknown whether factors such as seasonality determine the use of these structures. This analyses the seasonality of structure used by vertebrates. Forty-eight transverse structures crossing the A-52 motorway in north-western Spain are studied during the summer and winter of 2002–03. The use of structures by terrestrial vertebrates was monitored by tracks left in marble dust and photographic systems, and comparisons carried out by means of generalized lineal methods for count data. Structural factors mostly determined the differential use of passage types by species but seasonal changes were detected both in the intensity of use and in passage selection by some species.     

三速电磁风扇离合器应用

风扇是发动机水冷系统的重要组成部分,对保证发动机的工况稳定起着重要作用。电磁风扇离合器具有节能、降噪、响应迅速、快速稳定发动机水温、提高发动机使用寿命等优点,为解决风扇噪声、降低发动机油耗提供了新途径。