横风中不同行驶工况下高速列车非定常空气动力特性

通过三维大涡模拟(LES)数值计算方法,对横风中不同行使工况下高速列车的非定常空气动力特性进行研究。计算得到各工况下高速列车车体所受非定常空气动力的时域特性、频域特性、脉动特性,以及列车周围非定常流动结构。分析结果表明,横风中高速列车所受空气动力存在明显的非定常性。从各工况高速列车所受空气动力脉动的均方根值来看,各节车的非定常现象基本随着合成风向角的增加而增大。在高速列车所受非定常空气动力的频域特性方面,其峰值频率集中在斯托劳哈尔数0.05~0.2范围内,这一范围对应实车情况的频率为0.5 Hz~2 Hz,这与高速列车系统本身存在的一些固有振动频率接近,存在由横风引起高速列车系统共振、降低高速列车行驶安全性乃至引发高速列车脱轨倾覆的可能性。     

盾构下穿车站铁路轨道群施工技术

以沈阳市地铁一号线云沈区间土压平衡盾构下穿铁路轨道群工程为例,对施工中采取的技术措施进行了论述,着重介绍了盾构机掘进控制措施和地表沉降控制措施,可为类似工程的施工提供经验。     

高速铁路隧道高瓦斯大断面施工关键技术

针对刘家庄隧道出口段高瓦斯大断面隧道的自身特点,采取了无轨运输方案,对隧道施工的主要机械设备进行防爆改装,通过采取合理的开挖衬砌技术,引入瓦斯、视频系统及人员实时、动态监控系统,为隧道施工安全提供了可靠的保证,并且施工速度较快。     

级配碎石混合料的动力变形特性

采用在古典 C.B.R法的基础上 ,施加动荷载的简化试验方法 ,分析级配碎石混合料的动力变形特性 ,可用永久变形、弹性模量双指标指导混合料的组成设计 ,而合理的级配碎石基层材料组成 ,应考虑到材料与振动碾压工艺的相互作用。     

具有碎石基层的半刚性沥青混凝土路面的非线性有限元分析

在充分考虑碎石基层非线性(弹塑性)特性的基础上，采用非线性有限元法分析了吉林通化试验路3种路面结构面层底面及半刚性基层底面弯拉应力的变化规律，并对通化试验路2种具有碎石基层半刚性沥青混凝土路面结构的沥青混凝土面层的抗疲劳寿命进行了预估。     

成都市道路建设改革与研究

~~成都市道路建设改革与研究@钟强文$成都市市政工程设计研究院!四川成都610015~~~~     

列车运行图可调整度评价系统研究

在详细分析了列车运行图缓冲时间的大小及其分布规律对列车晚点传播影响的基础上，通过建立列车运行图调整系统，对给定晚点程度的列车进行模拟调整，从而计算出列车晚点恢复率，晚点传播区大小，连带晚点时间和关键列车运行线等。指标来达到对列车运行图可高速程度优劣评判的目的。     

Development and calibration of a long-distance passenger traffic assignment model

This paper studies the assignment of long-distance passenger traffic on a highway corridor network. First, we propose a traditional model for the long-distance traffic assignment considering interactions with local commuter traffic. It addresses the effect of local networks on highway corridors. An iterative algorithm is developed to solve for the exact solution. Then, to address the potential computational issues that arise therein, a decomposition method is proposed by introducing a new concept of corridor elasticity. An assignment procedure for long-distance passenger traffic is developed accordingly. Numerical tests show that the proposed decomposition method makes significant improvements in computational performance at a small loss of optimality. This decomposition method well approximates the exact assignment from the traditional formulation, especially when the highway corridors are near-saturation. The proposed decomposition method appears practical for application.     

基于需求弹性的城市公交票价优化方法及实证分析

城市公交票价是公交系统健康发展的重要因素，票价制定需兼顾公交企业的市场性和公益性双重属性，在保证服务质量的同时，考虑运营成本和最大限度吸引公交需求，实现经济效益和社会效益的双赢.在本文中，根据用户均衡理论，构建了城市多方式交通出行的需求分析模型，采用灵敏度分析方法给出了城市公交价格-需求弹性的计算方法.在此基础上，充分考虑了各种方式的交通特征、公交需求弹性、公交运营成本及政府限价等因素，提出了城市公交票价优化的数学规划模型，并给出了求解算法.最后，以国内某城市居民出行调查及公交运营数据为基础，分析了不同条件下公交客运需求的变化规律及城市公交票价的优化策略.     

Empirical estimation of price and income elasticities of air cargo demand: The case of Hong Kong

This paper estimates the price and income elasticities of air cargo demand and examines how they may change after the 2008 financial crisis. Using a set of time series data, we simultaneously estimate the aggregated demand and supply functions of air cargo at Hong Kong International Airport (HKIA). We find that during the entire sampling period of 2001–2013, the price elasticity for air cargo transport demand at HKIA ranges from −0.74 to −0.29, suggesting that air cargo demand in Hong Kong reacts negatively to price (as expected) but does not appear to be very sensitive to price. The income elasticity ranges from 0.29 to 1.47 and appears sensitive to seasonality adjustment approaches. However, in terms of the speed of changes, air cargo demand changes much faster than overall economy, indicating the presence of a pro-cyclical pattern of air cargo traffic with respect to the overall economy. Our analysis shows that air cargo demand becomes more sensitive to changes in both price and income after 2008.