Impact analysis of cordon-based congestion pricing on mode-split for a bimodal transportation network

This paper investigates the impact of cordon-based congestion pricing scheme on the mode-split of a bimodal transportation network with auto and rail travel modes. For any given toll-charge pattern, its impact on the mode-split can be estimated by solving a combined mode-split and traffic-assignment problem. Using a binary logit model for the mode-split, the combined problem is converted into a traffic-assignment problem with elastic demand. Probit-based stochastic user equilibrium (SUE) principle is adopted for this traffic-assignment problem, and a continuously distributed value of time (VOT) is assumed to convert the toll charges and transit fares into time-units. This combined mode-split and traffic-assignment problem is then formulated as a fixed-point model, which can be solved by a convergent Cost Averaging method. The combined mode-split and traffic-assignment problem is then used to analyze a multimodal toll design problem for cordon-based congestion pricing scheme, with the aim of increasing the mode-share of public transport system to a targeted level. Taking the fixed-point model as a constraint, the multimodal toll design problem is thus formulated as a mathematical programming with equilibrium constraints (MPEC) model. A genetic algorithm (GA) is employed to solve this MPEC model, which is then numerical validated by a network example.     

不同约束条件下中低速磁浮道岔主动梁自振特性

为了探究中低速磁浮道岔主动梁自振特性,以清远磁浮旅游线道岔系统为对象,建立3台车和2台车道岔主动梁的有限元模型,对安装面刚性约束和弹性约束下道岔主动梁进行有限元模态分析,与道岔主动梁自振特性实测结果进行对比,研究结果表明:安装面位移约束下3台车和2台车道岔梁的低阶模态频率显著大于实测值,弹性约束下道岔梁模态分析结果与实测结果接近,故中低速磁浮道岔梁有限元建模时应施加弹性约束;相较于2台车道岔梁方案,3台车道岔梁的垂弯模态频率有明显提高,但10~30 Hz频率内的横弯和扭转模态频率变化不大,仅仅增加中间台车抑制和减缓磁浮车岔15~20 Hz耦合共振的效果并不理想,提高道岔梁阻尼和加强道岔梁约束是更合理的选择。     

基于改进的PESP高速铁路列车运行图研究

借鉴国内外铁路列车运行图的编制理论和方法,基于周期规划事件(Period Event Scheduling Problem,PESP)的思想,构建周期性列车运行图模型。考虑我国列车运行组织的特点及周期性列车运行图模型的求解复杂性,对模型进行改造,以列车的总停站时间和总运行时间最小为目标,建立到发顺序为已知条件的周期运行图模型。改造后的模型为整数线性规划模型,大大降低模型求解复杂度。借助通用建模软件GAMS/COINBONMIN,编程求解得到列车的周期运行时刻表。     

城市公交区域调度双层优化方法研究

为了实现区域公交行车计划编制优化，构建了一个以区域内乘客候车时间为上层目标、以车队规模为下层目标的双层规划模型。由于上、下层目标之间存在的互相影响关系，导致模型难以获取最优解，选择将下层目标转化为模型的约束条件从而实现对模型的简便求解。对于车队规模的取值，提出了一种基于逆差函数的车队规模搜寻算法。进一步地，为了建立车队规模的约束条件，提出了3类核算时间点，并引入逻辑变量表征发车方案的选择，通过对核算时间点所对应的逆差函数值进行约束从而保证当前的发车方案能够满足既定的车队规模要求。在车队规模取值及约束条件确定的基础上，对模型进行求解即可得到不同车队规模取值情况下所对应的换乘时间表现最佳的发车方案。为了验证模型及求解思路的可行性，以哈尔滨市部分公交线路为例进行验证。结果表明：候车时间最优方案较初始方案能减少换乘时间10.3%，车队规模最优方案能减少初始车队规模15.2%；模型计算结果相当于为公交运营企业提供了可选择方案的效果边界，公交运营方可以通过结合预期的运营目标和实际公交规模选取最佳的发车方案，从而提高实际调度水平和运营效果。     

无线传感网络中QoS约束多播路由算法

分析了无线传感网络中具有时延、带宽和剩余能量等多QoS约束的多播路由问题.描述了一种适应于研究QoS多播路由的网络模型.提出了一种具有多QoS约束的能量有效的多播路由算法(EMRA),该算法成功地解决了无线传感网络中多播节点动态变化时的QoS路由选择问题.仿真实验证明了EMRA的有效性和优越性.     

考虑工程约束的发动机悬置支架拓扑优化

为了提高发动机悬置支架的结构性能和减轻质量,以发动机悬置在多工况下加权柔度最小化和频率最大化为目标,并考虑了工程约束条件,对支架结构进行多目标拓扑优化。根据优化结果设计出的新发动机悬置满足强度、耐久性和模态频率的要求,降低了开发风险,减少了实物试验,节约了开发成本。     

独立需求生产批量优化问题的遗传算法实现

生产批量问题是企业生产和管理中一个常见的约束批量问题,在假定问题中各产品的需求独立,同时满足能力约束和生产平衡的条件下,建立基于独立需求的遗传算法模型,实现使生产费用、生产准备费用和库存费用综合指标最小的生产批量算法。并通过对实际问题的计算验证该模型和算法的有效性和可行性。     

车辆下线检测系统的开发

该车辆下线检测系统能够自动识别某汽车所采用的发动机ECU、AT和AMT变速器TCU、整车防盗设备IMMO、乘员保护系统SRS及ABS防抱刹车系统控制单元的型号,并采用虚拟仪器技术,实现各种电控单元的故障诊断、实时参数测量和执行器测试等功能。此检测系统在该汽车生产线上的应用表明,其可作为车辆下线前车载电子器件是否正常工作的判断依据,并可同时提供车辆车况跟踪、统计和分析的实测数据。     

On the formulation of time-space prisms to model constraints on personal activity-travel engagement

The notion of time-space prisms has often been used in the context of describing activity-travel patterns of individuals. This paper presents a methodology for estimating the temporal vertices of time-space prisms using the stochastic frontier modeling technique. Observed trip starting and ending times are used as dependent variables and socio-economic characteristics and commute characteristics serve as independent variables. The models are found to offer plausible results indicating that temporal vertices of time-space prisms, though unobservable, can be estimated based on temporal characteristics of observed activity-travel patterns. Comparisons of stochastic frontier models of prism vertices and the distributions of prism vertices are presented using two activity data sets collected in the United States – San Francisco and Miami. Differences and similarities in temporal vertex locations are highlighted in the paper.     

文学翻译中的可译性限度——浅析翻译中原作与译作的关系

本文以中英文翻译中原作与译作为出发点,从原作与译作两者的体裁与风格、文化内涵与意想、社会与历史等几个因素浅述了文学翻译中的不可译性,论述了文学翻译中的可译性限度,从而表明文学翻译对于译作者的更高要求。