下承式钢管混凝土拱桥拱脚空间应力分析

采用8节点六面体单元和4节点壳单元,对大理河钢管混凝土拱桥进行了拱脚三维有限元分析,计算分析了各关键施工阶段拱脚应力的空间分布特征及其传力特性。针对个别阶段出现拉应力的情况,提出了施工工序的优化以及局部抗拉钢筋网的加强措施,监测结果显示,上述措施取得了良好的效果。结合拱脚局部传力特性的分析结果,可以得出,该桥拱脚受力主要以纵向受压为主,应力分布比较均匀,总体受力合理,可满足承载和传力的要求。     

基于线性LRS与基于SRS的空间数据转换方法

本文主要研究基于线性LRS的空间数据到基于SRS的空间数据转换,并以二维空间为例进行讨论。提出采用Lagrange型插值、差商及Newton插值、差分及等距采样点插值及最小二乘逼近插值4种整体插值的数据转换方法,提出分段线性插值和分段多项式最小二乘拟合插值两种分段插值的数据转换方法,并分析所提出插值转换方法的优缺点。     

符夹铁路青龙山特大桥空间刚架设计

小角度交叉桥梁结构中,空间框架结构具有结构高度低、整体刚度大、施工难度小、侧墙可打造多种景观需求等优点。符夹铁路青龙山特大桥地处中软土地基,小角度斜向上跨青符铁路联络线和两个下穿涵洞,对桥下通行净空和基础位置设置有较高要求。为了合理设计大桥,根据桥梁基本情况进行桥型方案比选,并对基础间断布置的空间刚架方案进行设计计算论证。结果表明,所选结构形式合理且为传统刚架结构提供新的扩展形式。     

Land use/transport models and economic assessment

This paper discusses the economic assessment of policies using land use/transport models. It argues that conventional forms of assessment focussing only on transport changes can underestimate the economic benefits of a policy. The paper argues that the benefits need to be measured by the changes of prices at the end of a trip and not just by the changes in travel costs. Models that do not estimate the changes of prices at the end of a trip cannot properly assess the impact of a policy.The model used in this paper is based on the MEPLAN software and estimates the location of households and employment and the interaction between them. It also estimates the cost of living for households and the production costs for employment. With these costs, it is possible to calculate the wider economic benefits beyond transport.The paper illustrates the assessment of policies for the Cambridge sub-region involving investment in public transport, orbital highway and congestion charging policies. The results forecast by the model are assessed in terms of the conventional cost-benefit using traveller’s surplus as benefits and compared with a wider assessment measure of compensation variation. It demonstrates that the last measure encompasses the wider benefits associated with transport policies which are not taken into account in conventional cost-benefit analysis.     

矮塔斜拉桥0号块隔板空间应力分析

通过建立空间模型,对宁江松花江特大桥0号块隔板处复杂的应力的状况进行了计算分析,根据空间应力分析的结果进行了预应力钢束的配置,并以此指导普通钢筋的布置。这种计算方法能够较好的模拟0号块的空间受力性能,能够真实地反应结构的应力分布情况,对于同类桥梁的设计有一定的借鉴作用。     

微观仿真在城市停车设施规划中的应用

为研究停车场规划和可达性对城市路网的影响,在世界范围内的三个不同城市应用微观仿真模型模拟停车设施规划。描述了三个城市采用的不同研究方法及得到的研究结果。三项研究都试图找到由驾驶人寻找停车位而造成的城市交通拥堵的解决方法。同时,在测试设计方案时,都使用了S-Paramics微观仿真模型。     

SCGE modelling in cost-benefit analysis: The Dutch experience

Spatial computable general equilibrium (SCGE) models offer opportunities for computing wider economic effects in cost-benefit analysis (CBA) in a theoretically satisfactory way. This is important for the correct estimation of additional economic benefits and international relocation impacts. In the Netherlands, this potential has only been reached partly. Many different types of models are actually used, none of which yet covers all relevant markets. In CBAs carried out in recent years, ad hoc methods were used more often than models, let alone SCGE models. Moreover, the usual presentation of the model outcomes appears as a ‘black box’ to policy makers. There is much work to be done, in extending SCGE models to strengthen their empirical basis, and in improving the presentation of the outcomes.     

基于DBSCAN的港口泊位自动识别算法设计

为更好地监测船舶动态和船舶在港口的作业情况,通过对K-Means算法和DBSCAN(Density-Based Spa-tial Clustering of Applications with Noise)密度聚类算法进行对比,选择DBSCAN密度聚类算法对港口泊位进行聚类,对港口泊位的位置和大小进行识别.基于船舶自动...