沥青碎石基层混合料的功能设计

针对现有高等级公路早期损坏现象,在分析结构类型影响程度的基础上,提出了柔性基层与半刚性基层优化组合的结构型式。文中基于沥青碎石基层的功能特点,确定了沥青碎石混合料的设计原则与设计指标,并采用最佳振动压实工艺、引入填充系数及具有侧限、能反映材料三向受力状态的动载压入法等具有新特点的设计方法分别确定了沥青碎石混合料的粗骨架类型、细集料分布及最佳填充系数,从而设计出满足基层功能要求的骨架-空隙型沥青碎石混合料。     

基于主元分析的车牌图像倾斜校正新方法

为解决机动车牌图像倾斜将对其字符分割与识别带来不利的影响,提出一种基于主元分析(PCA)的车牌图像倾斜校正新方法。在该方法中,PCA被用于求取坐标变换矩阵以进行图像旋转修正。将原始的像素坐标矩阵经过中心化后转换为2维协方差矩阵,再奇值分解为能反映图像倾斜方向的2维对角矩阵和坐标变换矩阵。算法的时间复杂度分析与试验结果均表明:相对于Hough等搜索倾角的校正方法,PCA方法缩短了计算时间1￣2个数量级,并且在污迹、光照不均等条件下也能获得较好效果。     

用MATLAB计算发动机悬置系统的固有频率和主振型

介绍了计算发动机橡胶悬置系统固有频率和主振型的过程,利用MATLAB编程并验证程序的正确性。通过程序的运行,能快速获得悬置振动系统的固有特性,为设计人员判断悬置系统是否会发生共振提供理论依据,也为进一步分析系统的响应打下了必要的基础。     

基于GIS的城市道路掘路交通影响分析系统研究

构建了基于GIS的城市道路掘路交通影响分析系统的体系，提出了局域路网，D矩阵反推模型、局域路网掘路交通分配模型和局域路网掘路交通状况评价方法，为掘路工程实施的可行性和交通组织方案的优选提供了依据。     

预应力曲线箱梁和异形箱梁的研究

近年来 ,国内外学者对曲线箱梁和异形箱梁的静力分析理论和计算方法作过大量的研究 ,但这些理论和方法在某种程度上都存在着一定的局限性 ,特别是在实际设计工作中 ,运用起来不能得心应手。为此本文在综合前人已取得经验下 ,针对桥梁结构设计中分析曲线箱梁、异形箱梁 ,经常遇到的难题进行了研究 ,建立一个较为完善的理论和方法 ,编制了等参元空间分析程序。在实际工程中进行实桥试验 ,验证了本文理论和方法的正确性。本文的研究工作更准确描述了箱梁的荷载响应 ,为设计人员提供直观的设计依据。对曲线箱梁和异形箱梁受力特性有了更一步的理解 ,并提出了新的见解     

Piecewise affine control for lane departure avoidance

This article presents the design of a lane departure avoidance system which is conceived to operate even in demanding manoeuvres with respect to the lateral vehicle dynamics. Piecewise affine state feedback and output feedback controllers are used to handle the nonlinear behaviour of the lateral tyre forces. The controllers are designed based on the search of a piecewise quadratic Lyapunov function casted as a bilinear matrix inequalities problem. Experimental tests demonstrate the performance of the controller in degraded road conditions.     

Flexible long range planning using low cost information

Contemporary transport planning requires a flexible modelling approach which can be used to monitor the implementation of a long term plan checking regularly its short term performance with easily available data; the original model is periodically updated using low cost information and this allows the evaluation of the changes to the plan which may be required. Such an approach requires models suited to regular updating and to the use of data from different sources. Models to update trip matrices from traffic counts have been available for some time; however, the estimation and/or updating of other model stages with low cost data has escaped analytical treatment. The paper discusses this idea and formulates the updating problem for an example involving a joint destination/mode choice model under various assumptions about the nature of the available data. Analytical solutions are proposed as well as some general conclusions.requests for offprints     

非线性消亡过程的二元相关性

多元随机变量相关性在许多方面引起关注，本文在二元随机变量之间各水平正相关及负相关的定义和相互关系的基础上讨论非线性纯消亡过程的相关水平。     

A zonal inference model based on observed smart-card transactions for Santiago de Chile

The collection of origin–destination data for a city is an important but often costly task. This way, there is a need to develop more efficient and inexpensive methods of collecting information about citizens’ travel patterns. In this line, this paper presents a generic methodology that allows to infer the origin and destination zones for an observed trip between two public transport stops (i.e., bus stops or metro stations) using socio-economic, land use, and network information. The proposed zonal inference model follows a disaggregated Logit approach including size variables. The model enables the estimation of a zonal origin–destination matrix for a city, if trip information passively collected by a smart-card payment system is available (in form of a stop-to-stop matrix). The methodology is applied to the Santiago de Chile’s morning peak period, with the purpose of serving as input for a public transport planning computational tool. To estimate the model, information was gathered from different sources and processed into a unified framework; data included a survey conducted at public transport stops, land use information, and a stop-to-stop trip matrix. Additionally, a zonal system with 1176 zones was constructed for the city, including the definition of its access links and associated distances. Our results shows that, ceteris paribus, zones with high numbers of housing units have higher probabilities of being the origin of a morning peak trip. Likewise, health facilities, educational, residential, commercial, and offices centres have significant attraction powers during this period. In this sense, our model manages to capture the expected effects of land use on trip generation and attraction. This study has numerous policy implications, as the information obtained can be used to predict the impacts of changes in the public transport network (such as extending routes, relocating their stops, designing new routes or changing the fare structure). Further research is needed to improve the zonal inference formulation and origin–destination matrix estimation, mainly by including better cost measures, and dealing with survey and data limitations.     

一种基质沥青快速升温装置的研制

现代交通的发展和道路等级的提高,对路用沥青的性能提出了更高的要求。在沥青中加入SBS、PE和橡胶粉等添加剂以改善基质沥青性能的方法得到了越来越广泛的应用,但改性沥青制作工艺对基质沥青的工作温度有严格的要求。探讨基质沥青的快速加热工艺和相关专用设备的研发是保证改性沥青制作质量的关键之一。