直线电机在轨道车辆运用中的三维分析

从三维方向分析,认为直线电机将原来旋转电机的电磁力,即内力变为了外力,从而给轨道车辆的设计概念带来重大的变化。通过对目前世界上直线电机车辆使用的实际业绩的分析,提出车辆质量可减轻的观点。     

一种求解线性规划问题的新方法

提出了一种求解线性规划问题的新方法：利用K-T条件及阳函数的凝聚特性，将多约束线性规划问题凝聚为单约束优化问题进行求解．最后给出了二维及三维线性规划问题的实例及相应的几何解释。     

应用模糊数学及AHP分析法优化铁路物流结构

结合铁路物流特殊性,分析现有合作企业的评价、优选方法在定性因素量化分析上的不足,提出应用模糊数学方法量化分析与评价候选企业的兼容性,利用层次分析法量化评价其素质的优劣,将量化结果与定量指标一起带入全局优化求解。使定性因素和定量因素在全局优化中结合起来,并应用(0 1)目标规划模型得到最优合作组合。通过算例证明该方法在优化铁路物流结构中的有效性。     

基于非线性规划的综合管廊断面尺寸设计优化

传统的综合管廊断面尺寸设计过分依赖相关规范取值以及经验的主观判断,造成管廊空间利用率不足等问题。 为提高综合 管廊空间利用率、降低建设投资成本,提出一种基于非线性规划对综合管廊断面尺寸设计进行优化的方法。 通过构建数学模型并 采用Matlab软件对案例优化进行精确计算,使设计结果更加科学合理。 最后通过案例分析验证方法的可行性,在控制成本的条件 下,将断面面积提高了20.8%,满足规范要求的同时提高了空间利用率。     

考虑弹性应变阈值的频率相关等效线性化方法

传统等效线性化方法由于原理简单、参数获取方便而广泛应用于工程场地非线性地震反应分析中．实际工程应用中发现,这种方法由于对各个频率分量采用了等效剪应变水平,使得地面最大峰值加速度和高频段计算结果明显偏低．若干实验表明,应变幅值对土的力学行为起着关键性作用,当应变低于弹性应变阈值时,土体处于线弹性状态,弹性应变阈值主要与土的塑性指数有关．本文在对各种频率相关等效线性化理论方法分析的基础上,结合弹性应变阈值理论,建立了考虑弹性应变阈值的频率相关等效线性化方法,运用本文方法对海口某实际场地进行了土层地震反应分析,对比了与传统等效线性化方法的差异;同时对不同覆盖层厚度遭遇不同地震动强度的地震动进行了计算分析．总结了不同覆盖层犀度下本文方法和传统等效线性化方法计算结果的差异及规律．     

考虑碳成本的城市交通拥挤定价模型研究

从研究国内外交通二氧化碳排放及收费和国内外拥挤定价现状入手,分析了城市交通二氧化碳排放的特征,在总结国内外碳税征收标准的基础上,建立了城市交通碳排放收费模型;将碳排放费用视为广义出行费用的一部分,进而建立了考虑碳排放成本的拥挤定价双层规划模型,选取实际案例验证其合理性与可行性,也为我国城市交通拥挤定价提出合理的建议.     

瓯江特大桥钢箱梁合龙控制研究

混合梁结构多用于斜拉桥,在大跨径连续刚构桥上应用较少,且混合梁连续刚构桥研究不够深入.瓯江特大桥主桥采用大跨径混合梁连续刚构桥,由于主跨跨中存在一个大节段钢箱梁段,故在设计、施工方面与常规混凝土连续刚构桥有较大不同,同时在施工控制过程中也出现了很多新问题.在常规混凝土连续刚构桥控制方法的基础上,对钢混结合段累计位移的突变问题进行分析,得到准确预测钢混结合段安装标高的方法.对钢箱梁吊装状态进行分析,得到准确的钢箱梁加工线形.对合龙时的温度效应进行分析,把握了温度影响规律,为钢箱梁的精确合龙提供依据.     

Data mining using regularized adaptive B‐splines regression with penalization for multi‐regime traffic stream models

This paper presents a new data mining method that integrates adaptive B‐spline regression and traffic flow theory to develop multi‐regime traffic stream models (TSMs). Parameter estimation is implemented adaptively and optimally through a constrained bi‐level programming method. The slave programming determines positions of knots and coefficients of the B‐spline by minimizing the error of B‐spline regression. The master programming model determines the number of knots through a regularized function, which balances model accuracy and model complexity. This bi‐level programming method produces the best fitting to speed–density observations under specific order of splines and possesses great flexibility to accommodate the exhibited nonlinearity in speed–density relationships. Jam density can be estimated naturally using spline TSM, which is sometimes hardly obtainable in many other TSM. Derivative continuity up to one order lower than the highest spline degree can be preserved, a desirable property in some application. A five‐regime B‐spline model is found to exist for generalized speed–density relationships to accommodate five traffic operating conditions: free flow, transition, synchronized flow, stop and go traffic, and jam condition. A typical two‐regime B‐spline form is also explicitly given, depending only on free‐flow speed, optimal speed, optimal density, and jam density. Copyright © 2013 John Wiley & Sons, Ltd.     

Traffic signal timing problems with environmental and equity considerations

Traffic signal timings in a road network can not only affect total user travel time and total amount of traffic emissions in the network but also create an inequity problem in terms of the change in travel costs of users traveling between different locations. This paper proposes a multi‐objective bi‐level programming model for design of sustainable and equitable traffic signal timings for a congested signal‐controlled road network. The upper level of the proposed model is a multi‐objective programming problem with an equity constraint that maximizes the reserve capacity of the network and minimizes the total amount of traffic emissions. The lower level is a deterministic network user equilibrium problem that considers the vehicle delays at signalized intersections of the network. To solve the proposed model, an approach for normalizing incommensurable objective functions is presented, and a heuristic solution algorithm that combines a penalty function approach and a simulated annealing method is developed. Two numerical examples are presented to show the effects of reserve capacity improvement and green time proportion on network flow distribution and transportation system performance and the importance of incorporating environmental and equity objectives in the traffic signal timing problems. Copyright © 2013 John Wiley & Sons, Ltd.     

Toll pricing framework under logit‐based stochastic user equilibrium constraints

This paper addresses the toll pricing framework for the first‐best pricing with logit‐based stochastic user equilibrium (SUE) constraints. The first‐best pricing is usually known as marginal‐cost toll, which can be obtained by solving a traffic assignment problem based on the marginal cost functions. The marginal‐cost toll, however, has rarely been implemented in practice, because it requires every specific link on the network to be charged. Thus, it is necessary to search for a substitute of the marginal cost pricing scheme, which can reduce the toll locations but still minimize the total travel time. The toll pricing framework is the set of all the substitute toll patterns of the marginal cost pricing. Assuming the users' route choice behavior following the logit‐based SUE principle, this paper has first derived a mathematical expression for the toll pricing framework. Then, by proposing an origin‐based variational inequality model for the logit‐based SUE problem, another toll pricing framework is built, which avoids path enumeration/storage. Finally, the numerical test shows that many alternative pricing patterns can inherently reduce the charging locations and total toll collected, while achieving the same equilibrium link flow pattern. Copyright © 2013 John Wiley & Sons, Ltd.