线性参考技术在铁路供电GIS中的应用

由于线性参考系统和动态分段技术在铁路等线性要素处理的过程中具有的优越性,使得现行的大多数铁路地理信息系统(GIS)都加入了这两项技术.本文探讨了线性参考系统和动态分段枝术的基本概念,介绍线性参考技术在铁路供电GIS中的应用.     

多元交通资料融合进行旅行时间预测——以台中港路为例

利用倒传递类神经网路,单以资料本身进行路段旅行时间预测,避免建立高复杂度的模式以及环境所产生的干扰下,建立不失精准度的预测模式。研究过程中发现：若仅考量路段中的车辆侦测器资料用以预测旅行时间,其预测精准度较劣於融合车辆侦测器资料及公车旅行时间资料之精准度,且发现预测精准度於尖峰时段较准确,故可推论使用一种以上的多元探测器所得之交通参数资料且於车流量较大之路段皆可提高路段旅行时间预测之精准度。     

GIS-T中交通事件的动态表达

针对当前GIS -T中对于交通事件表达的不足,首先利用交通波理论计算交通事件对路网影响范围的时空变化情况;其次基于线性参考和标准动态分段思想,在标准动态分段中增加时间维属性,通过程序扩展在现有GIS平台上实现时空动态分段方法,并用该方法实现交通事件影响临近路段范围的时空变化可视化表达.结果表明,利用时空动态分段方法可以...     

Modeling stochastic perception error in the mean-excess traffic equilibrium model

In this paper, we extend the α-reliable mean-excess traffic equilibrium (METE) model of Chen and Zhou (Transportation Research Part B 44(4), 2010, 493-513) by explicitly modeling the stochastic perception errors within the travelers’ route choice decision processes. In the METE model, each traveler not only considers a travel time budget for ensuring on-time arrival at a confidence level α, but also accounts for the impact of encountering worse travel times in the (1 − α) quantile of the distribution tail. Furthermore, due to the imperfect knowledge of the travel time variability particularly in congested networks without advanced traveler information systems, the travelers’ route choice decisions are based on the perceived travel time distribution rather than the actual travel time distribution. In order to compute the perceived mean-excess travel time, an approximation method based on moment analysis is developed. It involves using the conditional moment generation function to derive the perceived link travel time, the Cornish-Fisher Asymptotic Expansion to estimate the perceived travel time budget, and the Acerbi and Tasche Approximation to estimate the perceived mean-excess travel time. The proposed stochastic mean-excess traffic equilibrium (SMETE) model is formulated as a variational inequality (VI) problem, and solved by a route-based solution algorithm with the use of the modified alternating direction method. Numerical examples are also provided to illustrate the application of the proposed SMETE model and solution method.     

Global optimization method for mixed transportation network design problem: A mixed-integer linear programming approach

This paper proposes a global optimization algorithm for solving a mixed (continuous/discrete) transportation network design problem (MNDP), which is generally expressed as a mathematical programming with equilibrium constraint (MPEC). The upper level of the MNDP aims to optimize the network performance via both expansion of existing links and addition of new candidate links, whereas the lower level is a traditional Wardrop user equilibrium (UE) problem. In this paper, we first formulate the UE condition as a variational inequality (VI) problem, which is defined from a finite number of extreme points of a link-flow feasible region. The MNDP is approximated as a piecewise-linear programming (P-LP) problem, which is then transformed into a mixed-integer linear programming (MILP) problem. A global optimization algorithm based on a cutting constraint method is developed for solving the MILP problem. Numerical examples are given to demonstrate the efficiency of the proposed method and to compare the results with alternative algorithms reported in the literature.     

两台精密水准仪的校验比较分析

采用两台相同型号的精密水准仪,通过两名操作人员变换精密水准仪位置,比较了水准仪的视准误差,并列出视准误差的校验方法,可供水准仪间校验结果参考。     

一类非线性积分方程再生核空间中的线性化求解

笔者在文中利用再生核将非线性积分方程转化为线性积分方程求解,得到了此类方程解的结构,解决了解的存在性等问题.     

一种系统特征参数虚拟测试方法

通过虚拟电子试验平台EWB,对一、二阶线性系统特征参数进行了虚拟测试,整个测试过程形象直观,具有可操作性和实时性.测试结果准确、可靠,达到了预期的效果.     

中山市长江大桥蝴蝶拱桥空间稳定性分析

广东省中山市的长江大桥为蝴蝶拱桥。其造型新颖独特,受力复杂,对其进行稳定分析十分必要。采用ANSYS程序,建立了空间杆系有限元计算模型,并对其进行了第一类和第二类空间稳定性分析,对每一种模型分别进行线弹性和几何非线性计算,得到了一些重要结论。对该类桥梁的建设具有一定的借鉴作用。     

直线电机车辆沙漏式橡胶弹簧的非线性分析

对沙漏式橡胶弹簧在地铁、轻轨车辆上使用的优点做了介绍。运用有限元软件对沙漏式橡胶弹簧进行了计算。分析了地铁、轻轨车辆上沙漏式橡胶弹簧的载荷-挠度曲线的非线性特性,给出了动态下的当量静挠度。