铁路枢纽小运转列车径路优化

以枢纽小运转列车运营成本和货运站装卸费用最小为目标,考虑载重量、列车数和运行时间约束,建立了枢纽小运转列车路径优化模型.并以某铁路枢纽地区为例,运用ILOG CPLEX优化软件仿真求解,得出枢纽小运转列车的最优路径方案.实例证明模型是有效可行的,与实际运行比较,优化后的费用降低近5%,运输距离缩短近8.31%.     

A practical capacity model of a single track line

The paper presents a model for determining the practical capacity of a single track line, i.e. the maximum number of trains which can be run along it in a time unit under the condition that each train enters its bottleneck segment with a definite delay.

The input data used in the model are: geometrical characteristics of the bottleneck segment of the line under study, the intensity and structure of demand expressed by a number of trains which are run over the line in a given time unit, the scenario of traffic running over the line under study and the operational tactics of individual train categories processing on the bottleneck segment.

(Two tactics can be applied in the train processing on the line under study; first, the trains of individual categories are given different priorities in the processing, and second, all the trains have the same priority).

The output results of the model are average delays of trains of each category occurring within the train processing performed on the bottleneck segment of the line under study in a given time unit.     

Operating cost based cruise speed reduction for ground delay programs: Effect of scope length

Ground delay programs typically involve the delaying of aircraft that are departing from origin airports within some set distance of a capacity constrained destination airport. Long haul flights are not delayed in this way. A trade-off exists when fixing the distance parameter: increasing the ‘scope’ distributes delay among more aircraft and may reduce airborne holding delay but could also result in unnecessary delay in the (frequently observed) case of early program cancellation. In order to overcome part of this drawback, a fuel based cruise speed reduction strategy aimed at realizing airborne delay, was suggested by the authors in previous publications. By flying slower, at a specific speed, aircraft that are airborne can recover part of their initially assigned delay without incurring extra fuel consumption if the ground delay program is canceled before planned. In this paper, the effect of the scope of the program is assessed when applying this strategy. A case study is presented by analyzing all the ground delay programs that took place at San Francisco, Newark Liberty and Chicago O’Hare International airports during one year. Results show that by the introduction of this technique it is possible to define larger scopes, partially reducing the amount of unrecovered delay.     

摩托车配气机构运动学和动力学模拟分析

根据配气机构运动学和动力学分析,试制了优化凸轮实物,采用优化凸轮进行了发动机对比性能试验和耐久性试验.试验表明,优化凸轮能满足发动机性能要求,发动机耐久试验后,优化凸轮没有出现异常磨损现象,和模拟分析结果一致.     

基于刚柔耦合多体动力学模型的配气机构计算

通过在配气机构多刚体模型中引入柔性体,描述了配气机构的动力学性能;建立了柔性体气门弹簧,分析了气门弹簧动刚度的非线性行为,并且依据模态技术计算得到其动态应力;该方法为优化设计配气机构等机械产品及对其进行疲劳性能研究提供了依据。     

带转向延误的非对称多模式用户平衡模型及算法

为了在网络建模中更精确地反映交通网络和出行行为的复杂特征,从多模式用户平衡原理出发,综合考虑多模式和转向延误因素以及不同模式、路段和转向之间的非对称作用,利用变分不等式理论建立了带转向延误的非对称多模式用户平衡模型,并在精简对角化算法的框架内设计了求解算法。该模型集成了交通网络的诸多特征,且能直接刻画转向延误与转向流量之间的互动关系,避免了传统扩展网络法的缺陷。算例表明:该模型及其算法对问题的描述与求解是有效的。     

新型四冲程发动机液压可变配气机构的动态仿真与分析

提出一种新型的四冲程发动机液压可变配气机构。建立系统非线性数学模型,并分析配气机构的动态特性。仿真和试验结果表明,新的液压配气机构能实现可变气门正时及开度的控制,可适用于高转速发动机,具有一定的实用性。     

线控制相位差概率模型研究

在对现有线控制模型和算法进行分析的基础上提出按照概率思想求解相位差参数的策略。论文确立优化相位差的目标为通过车流在主干道上的停车次数和停车延误最小。建立相位差概率模型时,着重考虑4个影响因素:路段上车流行驶速度不均匀性,主干道上下行流量不均衡现象,相交道路上的转弯车流,短连线上的车辆排队约束。最后,论文用实际算例对建立的模型进行了验证,并对进一步的研究工作给出了建议。     

信号交叉口增量延误分析

为了对交通信号控制参数进行优化,需对交叉口延误进行定量分析与计算.对已有的平面信号交叉口增量延误模型提出了改进,并且对该模型进行了校正.针对交叉口处于非饱和与过饱和状态下的交通状况,用排队论分析并推导了交叉口增量延误公式.其结果既完善了现有的延误计算理论,又可为设置信号相位提供理论依据.     

发动机无凸轮轴气门驱动的研究与进展

阐述了在发动机上以电磁、电液、电气或其他方式驱动气门 ,实现无凸轮轴气门驱动 ,可以灵活改变气门正时 ,简化发动机结构 ,能有选择地闭缸 ,灵活改变发动机有效压缩比以适应多种燃料要求 ,使发动机获得比采用一般可变气门驱动更多的好处。无凸轮轴气门驱动的主要问题是响应速度不够高、气门落座冲击、能耗过高以及驱动系统复杂昂贵。目前无凸轮轴气门驱动还未达到大规模实用化的程度