大跨高低塔不对称斜拉桥抗震性能分析与评估

为了研究大跨斜拉桥的两阶段水准设防下的抗震性能,依托某大跨高低塔不对称斜拉桥,通过有限元模型建立了空间有限元模型,采用了反应谱和线性时程对比分析的方法。分析表明地震作用下,主桥的不利截面分别为双塔的塔底截面,其低塔受横向地震效应影响较大,高塔受纵向地震效应影响较大,设计配筋时应根据受力方向优化。     

高速公路软岩隧道复合支护机理的FLAC解析

结合软弱围岩隧道工程地质和支护设计特点 ,应用有限差分方法 ( FLAC)模拟研究了软岩隧道受力变形特征和围岩收敛曲线 ,并分析了复合支护结构中一次支护和二次支护结构的作用机理及作用效果。研究结果表明 ,软岩隧道开挖和一次支护后围岩支护压力随拱顶位移增加而连续减小 ,预测的最大位移均发生在隧道拱顶。但是 ,在同样支护压力下 ,考虑软岩流变特征的收敛曲线的拱顶位移要大得多 ,必须及时设置二次支护。另外二次支护结构还将起到承受流变压力的作用     

喷锚支护的时间效应与空间效应

喷锚支护是新奥法构筑隧道的主要支护手段，为使喷锚支护与围岩形成共同承载结构，必须在适宜的时机及根据适当的围岩变位量来确定恰当的喷锚支护结构。     

Time windows in workers' activity patterns: Empirical evidence from the Netherlands

This paper assumes that activities at the home and work location are important determinants of individuals' paths through time and space. Fixed activities at these locations determine to a large extent the duration and timing of time windows – blocks of time available for participation in travel and out-of-home non-work activities. Taking the time spent at home and at the workplace as a starting point, this paper classifies activity patterns on workdays into six groups with distinct home- and work-stay patterns. For this, data are used from the 1998 Netherlands National Travel Survey. The six clusters vary in terms of the duration and timing of time windows and some of the differences can be explained by commute characteristics, types of non-work activities performed, workers' sociodemographic attributes, and their spatiotemporal environment. However, the impact of sociodemographic and spatiotemporal variables on cluster membership is shown to be weak.     

徐宿高速公路碎石桩处理试验研究

主要结合睢宁三合同段中的碎石桩试验段研究碎石桩施工方案的可行性和处理的实际效果,完善碎石桩的施工工艺。通过室内土工试验、静力触探试验、标准贯入试验、动力触探试验、瞬态瑞利波试验等检测手段的对比研究,探讨碎石桩的检测方法和碎石桩加固效果检测的最佳检测时间。     

车载动态实时可视化交通信息服务系统

一种新型城市交通信息服务系统,它采用GPS接收机、数码像机、有线/无线智能传感器、辅以人工等方式完成路况信息采集,经控制中心处理后按1～3次/min频率生成全面、综合反映路况信息的实时、动态交通图,通过无线传输为公众提供实时、动态路况信息,并用全新概念的车载显示器Skipper显示路况信息,实现道路车辆均衡化、提高道路利用率。论述了其开发背景、系统构成及工作原理、核心产品开发与运用等。     

符号时间序列方法在汽油机燃烧循环变动特征分析中的应用

应用一种新的分析方法———符号时间序列方法对汽油机燃烧循环变动进行了研究。测量得到了某汽油机16种不同工况下的示功图,从提高精度与有利于数据的符号化观点出发,确定以缸内峰值压力作为汽油机燃烧循环变动的表征参数,把符号时间序列分析的具体技术和实施途径应用于试验数据,获得了汽油机燃烧循环变动随转速与负荷的变化规律,提出了利用改进的SHAN NON熵作为汽油机燃烧循环变动的评价指标的新观点。研究结果表明:该方法能较好地应用于汽油机燃烧循环变动特征分析。     

降雨作用下高填土质路堤边坡的渗流稳定分析

针对现行的高填土质路堤边坡,基于饱和—非饱和渗流数学模型,设计了二维非稳定渗流程序,通过模拟因雨水入渗引起的暂态渗流场,分析土体中含水量、基质吸力的变化规律;采用等效粘聚力的概念,利用延伸的MOHR COULOMB破坏准则对路堤边坡进行了弹塑性有限元分析,进而得出路堤边坡在不同降雨时刻的安全系数;最后分析了降雨重现期、土参数φb和由路堤施工所引起的土体渗水性系数的各向异性对边坡渗流稳定的影响。     

An Exploration of the Relationship between Timing and Duration of Maintenance Activities

The timing and duration of an activity episode are two important temporal aspects of activity-travel behavior. Understanding the causal relationship between these two variables would be useful in the development of activity-based travel demand modeling systems. This paper investigates the relationship between these two variables by considering two different causal structures – one structure in which time-of-day choice is determined first and influences duration and a second structure in which activity duration is determined first and affects time-of-day choice. These two structures are estimated within a discrete-continuous simultaneous equations framework employing a full-information maximum likelihood methodology that allows error covariance. The estimation is performed separately for commuter and non-commuter samples drawn from a 1996 household travel survey data set from the Tampa Bay area in Florida. The results of the model estimation effort show that the causal structure in which activity duration precedes or affects activity timing (time of day choice) performs better for the non-commuter sample. For the commuter sample, the findings were less conclusive with both causal structures offering equally good statistical measures of fit. In addition, for the commuter sample, all error correlations were found to be zero. These two findings suggest that time of day choice and activity episode duration are only loosely related for the commuter sample, possibly due to the relatively non-discretionary and inflexible work activity and travel.     

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。