Pre-timed control for an under-saturated and over-saturated isolated intersection: a Bee Colony Optimization approach

In this paper we study the problem of determining the optimum cycle and phase lengths for isolated signalized intersections. Calculation of the optimal cycle and green phase lengths is based on the minimization of the average control delay experienced by all vehicles that arrive at the intersection within a given time period. We consider under-saturated as well as over-saturated conditions at isolated intersections. The defined traffic signal timing problem, that belongs to the class of combinatorial optimization problems, is solved using the Bee Colony Optimization (BCO) metaheuristic approach. The BCO is a biologically inspired method that explores collective intelligence applied by honey bees during the nectar collecting process. The numerical experiments performed on some examples show that the proposed approach is competitive with other methods. The obtained results show that the proposed approach is capable of generating high-quality solutions within negligible processing times.     

An agent‐based simulation model to assess the impacts of introducing a shared‐taxi system: an application to Lisbon (Portugal)

This paper presents a new concept of urban shared‐taxi services. The proposed system has a new organisational design and pricing scheme that aims to use the capacity in traditional taxi services in a more efficient way. In this system, a taxi acting in ‘sharing’ mode offers lower prices to its clients, in exchange for them to accept sharing the vehicle with other persons who have compatible trips (time and space). The paper proposes and tests an agent‐based simulation model in which a set of rules for space and time matching between a request of a client and the candidate shared taxis is identified. It considers that the client is only willing to accept a maximum deviation from his or her direct route and establishes an objective function for selecting the best candidate taxi. The function considers the minimum travel time combination of pickup and drop‐off of all the pool of clients sharing each taxi while allowing to establish a policy of bonuses to competing taxis with certain number of occupants. An experiment for the city of Lisbon is presented with the objectives of testing the proposed simulation conceptual model and showing the potential of sharing taxis for improving mobility management in urban areas. Results show that the proposed system may lead to significant fare and travel time savings to passengers, while not jeopardising that much the taxi revenues. Copyright © 2014 John Wiley & Sons, Ltd.     

飞轮储能系统建模与仿真研究

为研究独立电力系统采用飞轮储能系统对大功率脉冲负载的供电性能,本文在分析了飞轮储能系统工作原理基础上,对飞轮储能系统建模与仿真开展了研究。采用了PSCAD/EMTDC软件搭建按照其实际组成搭建了SPWM控制的变流器及触发控制信号仿真模型,利用具有大转动惯量、小摩擦系数和小阻力转矩的负载模拟飞轮转子,建立了飞轮储能系统的全系统模型。通过对建立的模型进行仿真,给出了飞轮储能系统在储能状态、放能状态及两者之间的转换过渡时刻的转速、转矩、电流及母线直流电压响应曲线,深入分析表明,该仿真结果与理论完全一致,证明了飞轮储能负载的仿真模型是正确有效的。研究的相关结论可用于相关电力系统供电稳定性的仿真设计。     

基于Simulink模型的电动汽车传动系优化程序设计

简述了电动汽车的动力传动系统的优化设计技术,自行设计了一种优化传动系速比的方法调用AD—VISOR2002仿真软件中的Simulink模型搭建了优化传动系速比的目标函数,详细介绍了优化程序设计的基本原理与程序代码的实现,并通过实例加以说明和验证。     

铁路笨零货物装载优化模型和算法

笨零货物装载优化问题是NP完备问题。根据笨零货物运输条件和铁路现场实际操作情况,建立以车辆装载率最大化为目标的装载优化数学模型,约束条件包括:货物合重心偏移量的约束;重量约束;体积约束;下部支撑约束;稳定性约束等。采用遗传算法进行求解,详细阐述用遗传算法求解该问题的关键技术,重点论述二维、三维装载的算法实现。给出算法实例,表现出算法能得到满意的结果。     

利用EXCEL智能化修船套料下料单

提高下料的准确性和快速性是修船企业应对修船短、频、快的特点和提高钢材的利用率以加强成本控制减少浪费的重要途径之一。本文运用EXCEL的计算功能模块来优化设计钢材的套料和下料单,以达到准确和快速掌握钢材的使用状况和统计数据的目的。     

CGX巡洋舰多学科设计优化模型的再分析

传统的设计螺旋方法由于割裂了学科间耦合,得到的设计往往是满足设计要求的设计而不是最优的设计.多学科设计优化(MDO)方法正是一种能得到最优设计的新设计方法,MDO目前被广泛应用于复杂工程系统的设计中.文中对多学科设计优化的理论进行了简要综述,在此基础上为了演示MDO方法应用于舰船设计,采用iSIGHT对国外的CGX巡洋舰概念设计的13个模块进行了集成,建立了MDO模型并优化,得到了较好的优化解.在此基础上采用神经网络重新建立了该MDO模型,将优化结果和原MDO模型优化结果进行了比较.     

Maximizing bus discharge flows from multi-berth stops by regulating exit maneuvers

Upon having loaded and unloaded their passengers, buses are often free to exit a multi-berth bus stop without delay. A bus need not wait to perform this exit maneuver, even if it requires circumventing one or more other buses that are still dwelling in the stop’s downstream berths. Yet, many jurisdictions impose restrictions on bus entry maneuvers into a stop to limit disruptions to cars and other buses. Buses are typically prohibited from entering a stop whenever this would require maneuvering around other buses still dwelling in upstream berths. An entering bus is instead required to wait in queue until the upstream berths are vacated.Analytical models are formulated to predict how bus discharge flows from busy, multi-berth stops are affected by allowing buses to freely exit, but not freely enter berths. These models apply when: a bus queue is always present at the stop’s entrance; buses depart the entry queue and enter the stop as per the restriction described above; and the stop is isolated from the effects of nearby traffic signals and other bus stops. We find that for these restricted-entry stops, bus-carrying capacities can often be improved by regulating the exit maneuvers as well. This turns out to be particularly true when the stop’s number of berths is large. Simulations show that these findings still hold when a stop is only moderately busy with entry queues that persist for much, but not all of the time. The simulations also indicate that removing any restrictions on bus exit maneuvers is almost always productive when stops are not busy, such that short entry queues form only on occasion, and only for short periods. We argue why certain simple policies for regulating exit maneuvers would likely enhance bus-stop discharge flows.     

行人腿型冲击器肌肉材料参数反求

aPLI先进行人腿型冲击器在碰撞测试中的生物仿真度,在很大程度上取决于其几何结构及其模拟腿部肌肉的合 成橡胶的超弹性力学特性。根据橡胶准静态单轴压缩试验数据,分别对用于表述橡胶超弹性的Ogden和Mooney-Rivlin本 构模型进行材料参数拟合,得到相应的材料参数并将拟合曲线与试验曲线进行比较,对比不同本构模型的拟合精度。结 果表明,2阶 Ogden材料模型更符合试验结果。为提高有限元模型中肌肉橡胶材料参数的准确性,重构压缩试验有限元 模型,以拟合得到的2阶Ogden本构模型材料参数为初始值,通过将有限元与优化策略相结合,基于自适应响应面法对2 阶Ogden模型中μ1、α1、μ2、α2这4个材料参数进行优化,获得该材料在准静态压缩状态下的一组最佳材料参数。