公交车进站停靠对绿波控制的影响

在实际绿波控制应用中,公交车进站停靠所形成的交通瓶颈往往会使路段实际通行能力降低,对绿波控制效果产生一定的影响.应用集散波理论分析了公交车进站停靠对最大绿波带宽的影响,并提出了在无公交车停靠和有公交车停靠两种情况下,不同的绿波控制相位差及最大绿波带宽的计算方法,在VISSIM仿真平台进行了在线仿真,仿真结果表明:考虑公交瓶颈影响下获得的绿波带参数,其控制效果明显优于未考虑公交瓶颈影响下的控制效果,同时也验证了应用集散波理论获取公交停靠瓶颈下绿波控制参数方法的可行性.     

Travel demand estimation risk for high‐speed railway transport considering travel price competition

The Hokkaido Shinkansen (HS) bullet train line is under consideration to open in 2020. In this study, travel demand is estimated for the HS. Because some explanatory variables that are used for such estimation can have estimation errors, travel demand estimation risk is also calculated. In addition, because the HS can compete with airlines for modal share, the impacts of travel price competition (TPC) on the travel demand and the demand estimation risk are also estimated. In this study, the travel demand estimation risk is measured as the variance or the SD of the stochastic travel demand. The analysis reveals the following: the modal share of HS is 16% less when TPC is considered than when it is not considered; TPC causes the travel demand estimation risk to decrease; the probabilities of the HS operating at a deficit with and without consideration of TPC are calculated as 31.2% and 1.25%, respectively, and the increase in the mean consumer surplus accruing from the HS is calculated as JPY 47bn/year ($US588m/year) without TPC and as JPY 66bn/year ($US825m/year) with TPC. Copyright © 2012 John Wiley & Sons, Ltd.     

Differences in air passengers’ buying behaviour: findings from Korean and Australian international passengers

Abstract

This paper investigates how air passengers’ expectations, ticket price, airline service quality, value, passenger satisfaction and airline image determine their buying behaviour. To test the conceptual frameworks, path analysis was applied to data collected from Korean and Australian international passengers to examine differences between these two groups. Further analyses were undertaken on different passenger segments between national and foreign airline passengers. The results of the path analysis reveal that air passengers’ buying behaviour differs significantly between Korean and Australian international passengers. Results also reveal that the determinants of air passengers’ buying behaviour differ by airlines.     

Performance evaluation and obstacle factors analysis of urban public transport priority

ABSTRACT

Through the comprehensive consideration of four subsystems – overall development level, infrastructure construction, public transportation service level and policy support – an index system of public transport priority performance evaluation is established. A performance evaluation of bus priority implementation in Wuhan City from 2007 to 2016 is carried out by applying the difference coefficient CRITIC-TOPSIS model. The obstacle factor model is also used to diagnose the factors affecting the priority performance of urban public transport. The research results show that, during this decade, the comprehensive performance of Wuhan City’s public transport priority developed from poor to medium, then to good and finally to excellent. The overall development level and infrastructure construction performance subsystems have the highest obstacle degree, followed by public transportation service levels and policy support performance subsystems. The research idea and method of this paper provide a realistic basis for promoting the priority performance of urban public transport.     

某干旱及大温差地区公路温差气候区划研究

根据新疆维吾尔自治区干旱大温差的气候特点,利用气象年极端最低气温、7月平均最高气温、年降水量及潮湿系数对新疆地区100多个观测点数据进行分析,将干旱温差强度分为轻度、一般、重度及特大4个等级,这一分区对公路沥青路面的设计与施工有据可依,具有实用价值。     

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为深入分析航空公司动态价格竞争的复杂性,运用非线性动力学的分支理论,构建了基于差异化的航空公司动态价格竞争模型,依据动力学稳定性判定条件,讨论了该模型均衡点的存在性、存在个数与稳定性,数值仿真了不同条件下模型复杂的动力学行为.仿真结果表明,航空公司价格调整速度对模型的稳定性有明显的影响,一旦价格调整速度超过某一临界值,系统将表现出分岔、混沌等复杂的动力学现象;与Nash均衡利润相比,在混沌状态下航空公司的利润均显著下降;差异化战略对航空公司定价、利润有重要影响,保持和加强对竞争对手的差异化优势有助于自身获得更大的市场竞争优势.     

纵向预应力对箱梁剪力滞效应的差分解

选取3次抛物线变化的纵向位移,通过能量变分原理得到悬臂箱梁的剪力滞基本微分方程,再利用有限差分法进行求解,将该方法用于分析纵向预应力等效荷载作用下的悬臂箱梁剪力滞效应.运用ANSYS有限元软件建立模型,采用Solid 95单元模拟箱梁,采用Link8单元模拟预应力钢束,分析在纵向预应力作用下箱梁剪滞系数分布规律并与差分法求解的结果进行对比.经过对比,验证了差分法求解纵向预应力等效荷载作用下箱梁剪滞效应的可行性,同时分析了纵向预应力对箱梁剪滞效应的影响.     

基于模型试验的矿山法地铁隧道支护结构病害检测与识别

为提高矿山法地铁隧道支护结构病害检测与识别的准确性,采用基于时域有限差分的数值模拟方法,建立常见形状空洞、充水空洞、不同填充介质脱空以及钢格栅拱架、H型钢架下空洞模型,模拟探地雷达波在不同病害中的传播规律,并通过青岛地铁3号线探测实例验证。结果表明:空洞病害雷达反射波通常呈双曲线形状,反射信号强,但上三角形空洞图像与其他空洞图像有较大差异,表现为倾斜平行的同相轴特征;当空洞或脱空内部含水时,空洞或脱空下部出现明显反射波;钢结构雷达波反射强烈,会对钢结构下方病害探测产生干扰,在实际探测中,应将初期支护与二次衬砌分开探测。     

隔振器分布对浮筏隔振系统隔振性能的影响

目前,国内外对于浮筏隔振系统各个方面的研究都已很多,通常采用的是动力学建模及理论分析的方法。但此法通常是将隔振器简化为只有垂向刚度的弹簧和阻尼的单元,而忽略了隔振器的横向刚度及阻尼对系统的影响,简化模型与实际情况有一定差别,因此本文采用有限元法对浮筏隔振系统进行仿真分析。本文根据隔振器的选用及布置原则提出几种合理的布置方案,利用 ansys 有限元软件对提出的布置方案进行仿真,采用振级落差的隔振指标来评估浮筏隔振系统的隔振效果,为隔振器的布置方案设计提供一种思路。     

四点中心差分法在EGR阀开度PID控制算法中的应用研究

EGR 系统通过调整阀开度实现对再循环已燃气体的流量控制,现有 EGR 阀开度控制算法多采用传统PID 控制算法。传统 PID 控制算法中,差分项对数据误差和干扰较敏感,易引起振荡。针对这一问题,采用四点中心差分法代替原有一阶后向差分算法,考虑过去4个时刻的误差,通过时间加权求和得到优化的差分量,该方法可减少数据误差对差分项的干扰。采用阶跃响应曲线法对 PID 参数进行整定。追踪三角波目标开度的试验结果表明,利用该改进算法及参数整定方法可得到一套控制效果较好的 EGR 阀控制算法及控制参数,所控 EGR 阀可准确跟踪目标开度的快速变化,满足实际使用的要求。