A Pareto-improving hybrid rationing and pricing policy with multiclass network equilibria

This paper extends the work on Pareto-improving hybrid rationing and pricing policy for general road networks by considering heterogeneous users with different values of time. Mathematical programming models are proposed to find a multiclass Pareto-improving pure road space rationing scheme (MPI-PR) and multiclass hybrid rationing and pricing schemes (MHPI and MHPI-S). A numerical example with a multimodal network is provided for comparing both the efficiency and equity of the three proposed policies. We discover that MHPI-S can achieve the largest reduction in total system delay, MHPI can induce the least spatial inequity and MHPI-S is a progressive policy which is appealing to policy makers. Furthermore, numerical results reveal that different classes of users react differently to the same hybrid policies and multiclass Pareto-improving hybrid schemes yield less delay reduction when compared to their single-class counterparts.     

Formulating cargo inventory costs for liner shipping network design

This study examines how to incorporate the inventory costs of containerized cargoes into existing liner service planning models such that the designed networks could be improved while not causing extra modeling/computational burden. Two approaches are compared: (i) not considering the inventory costs at all and (ii) incorporating the inventory costs associated with onboard time and those related to transshipment by assuming a fixed connection time. The two models are compared with the ideal model capturing the exact inventory costs on a route choice problem and a capacity planning problem based on extensive randomly generated and practical numerical experiments. The results show that: first, ignoring the inventory costs in service planning models may lead to network design with much higher costs (poor network design decisions); second, in service planning models assuming weekly frequency, the inventory costs associated with onboard time could be formulated exactly, and those related to the connection time of weekly services could be approximated by assuming fixed connection time of 3.5 days for ports with 1 day’s minimum connection time and 4.5 days for ports with 2 days’ minimum connection time.     

A logit-based model for measuring the effects of transportation infrastructure on land value

Mutual interactions between transportation and land use have long been debated. Despite progress made in computational technology, the study of these interactions is not adequately developed. The most important aspect of such interactions is given by the changes in land values due to changes in transportation infrastructures. We consider the behavioural features of these interactions along with the constraints on the land and/or zoning restrictions and propose a reliable model for the first time to predict land value changes with respect to changes in transportation facilities and accessibility. The proposed model is a logit-based mathematical programming methodology where the relative price of land is predicted with respect to transportation accessibility, neighbourhood amenities, location premium, availability of land, and zoning regulations. A real-world case study is used to exhibit the applicability of the proposed methodology and demonstrate the efficacy of the algorithms and procedures.     

预应力混凝土连续箱梁桥混凝土疲劳应力限值研究

大量预应力混凝土连续箱梁桥在服役期内发生腹板斜裂缝病害,引发了研究人员对于混凝土疲劳应力问题的探讨．结合中国的预应力混凝土桥涵设计规范与混凝土结构设计规范（GB50010—2002）、英国BSEN1992—1—1混凝土设计细则、欧洲CEB—FIPMC1990规范和美国AASHTO2004规范关于混凝土疲劳应力验算的规定,对混凝土疲劳应力验算方法进行了比较．并以某预应力混凝土连续箱梁桥为例,对各规范中混凝土疲劳验算的具体过程进行了计算与分析,验证了规范的合理性以及适用性．分析结果表明,中国规范的疲劳应力限值较国外规范偏高．在对构件进行疲劳设计时,推荐采用CEB—FIP规范提供的验算方法．     

我国路域生态系统建设中存在的问题及对策

针对我国路域生态系统建设中存在的很多问题,从不同方面分析了问题产生的原因,提出注重人与自然和谐统一的理念,合理运用生态学、经济学理论。全公路行业在这个问题上达成共识是建设和谐路域生态系统的根本途径。     

地铁振动传播的峰值和频率特征分析

采用2种不同刚度的扣件,对地铁振动传播途径各主要部位进行了振动测试,获得了各部位相应的振动加速度时程数据。首先,统计了时域振动加速度峰值及其变化情况;然后,通过傅里叶变换计算了各部位振动的频谱,对比分析了振动在传播过程的频谱变化规律;最后,计算分析了地表Z振级变化。结果表明,扣件刚度在一定范围内变化,对60 Hz附近的振动峰值影响有限,隧道壁和地表的竖向及横向振动振级分别在650 Hz和340 Hz附近迅速下降,之后趋于平缓。使用刚度较小的扣件有利于减小地表竖向振动,但不利于减小地面横向振动。     

深埋双线铁路隧道衬砌高水压分界值研究

为研究深埋双线铁路隧道衬砌高水压分界值以及高水压作用下的衬砌受力状态,基于双线铁路隧道设计标准,利用有限元软件计算和分析双线铁路隧道衬砌在不同水压作用下隧道衬砌安全系数的变化规律,确定双线铁路隧道衬砌的高水压分界值。研究结果表明:Ⅱ、Ⅲ级围岩条件下水压力在0~0.05 MPa(约等于隧道净高一半)和Ⅳ、Ⅴ级围岩条件下水压力在0~0.1 MPa(约等于隧道净高)范围内变化时,隧道断面安全系数基本不变。在Ⅱ、Ⅲ级围岩条件下,双线隧道的高水压第一分界值为0.08~0.20 MPa;高水压第二分界值可取为0.40MPa。在Ⅳ、Ⅴ级围岩条件下,双线隧道的高水压第一分界值为0.12~0.35 MPa;高水压第二分界值为0.50 MPa。双线铁路隧道采用标准设计图进行设计时,能够承受的最大静水头为50 m,超过50 m的静水头,则需要优化断面。     

托运人在不同时空下的选择行为差异揭示

某一因素对托运人选择行为的影响会随着空间和时间变化. 既有研究多关注特定空间或时间的托运人选择行为,较少进行横向(空间)和纵向(时间)比较. 为探索托运人选择行为差异及变化规律,采集不同时空的5 个数据集,构建多类线性或非线性效用函数的多项 Logit 模型及混合Logit 模型. 结果表明：在空间维度,某一地区托运人选择行为与其他地区显著不同;在时间维度,伴随货运业快速发展,货运方式选择模型适用年限呈缩短趋势.     

城市轨道交通常态与非常态短期客流预测方法研究

城市轨道交通客流特征除表现为常态的周期性、季节性及高峰性外,还会因节假日、体育赛事、城市大型活动、突发事件、特殊天气等因素表现出差异性和特殊性,本文对较为成熟的常态及研究较少的非常态客流预测方法进行了实验.首先利用通用的ARIMA时间序列预测算法分析样本历史数据实现常态日客流预测;其次针对客流特殊因素提出时间序列及回归分析的组合模型,同时引进虚拟变量和结合相似日样本数据进一步改进,实现非常态预测问题的高精度求解.仿真计算结果表明,本文方法对解决短期客流预测具有良好的适用度,尤其同样本同预测周期条件下的非常态组合改进模型和常用单一时间序列模型的对比,证明改进模型可以很好地应用在客流特征既包括随时间固有不变的性质又表现出特殊因素的研究中,具有较强的自适应性和更好的预测精度.     

基于价值流图析的精益生产研究

企业的生产过程实际上是价值流动并增加的过程,运用价值流图析研究企业的价值流流动情况,并根据精益生产的原理,运用拉动和流动,使企业创造价值的各个步骤不间断地流动起来,使价值流进行最高效的运动,并且消除不必要的浪费,从而使企业的利润最大化。