复线布置桥梁桥区水域船舶通航效率研究*

为研究复线布置桥梁桥区水域的通航效率,将其考虑为一个串联排队系统进行数学建模与计算机模拟。以苏通大桥与沪通大桥的桥区水域为例,计算日常与高峰两个时段桥区水域通航系统的效率。将单桥通航系统视为M/M/1型排队系统计算其通航效率,并进行两种通航系统的对比分析,找到复线布置桥梁桥区水域通航效率的两种瓶颈与瓶颈产生的机理,为复线布置桥梁的桥位选址和营运期的交通组织提出相关建议。     

迷惑式干扰箔条弹发射时间要求

从攻击机与舰艇距离的角度对迷惑式干扰箔条弹的发射时机进行分析;从排队论的角度对多批次攻击机来袭时,迷惑式干扰的发射间隔问题进行了探讨。     

基于港口枢纽处TOD公交站点选址模型的设计

本文针对中小型沿海城市提出的成本模型嵌入到公交站点优化方案中,构建各项成本的表达式,整合并建立以成本最小为目标的公交站点选址模型,对TOD公交站点的选址进行合理规划。此模型可有效运用到在中小型沿海城市中港口枢纽处的公交站点合理设置中,即实现乘客从轮渡到公交的零换乘,又能使港口枢纽对港口枢纽出入口与城市道路交汇处的交通现状影响达到最小,公交的通行能力达到最高。     

考虑集结延误的列车编成辆数问题研究

货车集结是不可避免且耗时较长的技术作业环节，编成辆数与车辆集结延误时间密切相关.针对编成辆数问题，建立描述车辆在调车场集结过程的批到达批服务排队模型，分析车辆集结队长及延误时间等指标，并从经济角度求得最优最小编成辆数.结果表明，最优最小编成辆数受车组到达规律、车流到达强度和列车发车时间间隔影响.到达车组大小满足指数分布时，采用最优最小编成辆数策略节省经济效益优于几何分布和负二项分布；车流到达强度较小时，节省经济效益更显著；列车出发时间间隔分布满足几何分布时，效益优于负二项分布和均匀分布.     

A recursive, cell processing model for predicting freeway travel times

Travel time information influences driver behaviour and can contribute to reducing congestion and improving network efficiency. Consequently many road authorities disseminate travel time information on road side signs, web sites and radio traffic broadcasts. Operational systems commonly rely on speed data obtained from inductive loop detectors and estimate travel times using simple algorithms that are known to provide poor predictions particularly on either side of the peak period. This paper presents a new macroscopic model for predicting freeway travel times which overcomes the limitations of operational ‘instantaneous’ speed models by drawing on queuing theory to model the processing of vehicles in sections or cells of the freeway. The model draws on real-time speed, flow and occupancy data and is formulated to accommodate varying geometric conditions, the relative distribution of vehicles along the freeway, variations in speed limits, the impact of ramp flows and fixed or transient bottlenecks. Field validation of the new algorithm was undertaken using data from two operational freeways in Melbourne, Australia. Consistent with the results of simulation testing, the validation confirmed that the recursive model provided a substantial improvement in travel time predictions when compared to the model currently used to provide real-time travel time information to motorists in Melbourne.     

基于多级排队模型的锚地规模仿真研究

通过分析锚地所在"航道-锚地-泊位"系统的作业流程,构建M/M/l/N～M/M/n/K两级排队模型,运用离散事件系统仿真软件Simevent对该模型进行建模仿真,以此来进行锚地规模的研究,并通过实例对该模型进行验证同时分析船舶到达率、泊位数以及锚位数的变化对平均等待时间和平均等待队长的影响.     

船舶可调桨网络控制系统研究

可调螺距螺旋桨(简称可调桨CPP)控制系统是船舶推进系统的重要子系统。随着船舶推进系统在响应速度和操纵性能等方面提出的更高要求,CPP控制系统已从传统的控制系统发展到分布式的网络控制系统,而网络控制的引入必然产生不确定的网络时延。因此,本文采用支持向量机 广义预测控制 队列机制的混合控制方法设计了网络控制器。仿真结果表明,该控制算法能有效地补偿网络时延对CPP控制系统的影响,使之具有较好的稳定性和鲁棒性。     

港口航道通过能力研究综述

合理设计和规划航道通过能力,有助于提高港口系统的作业效率和服务质量。在总结影响港口航道通过能力因素的基础上,分别从确定性数学分析方法、基于排队论的分析方法和仿真分析方法3个方面分析了港口航道通过能力计算模型和仿真模型。给出各种方法的研究思路和优缺点,其中数学分析的方法侧重静态分析,而仿真分析的方法侧重动态分析,且能综合考虑各种影响航道通过能力的因素。     

基于排队论的大型舰船甲板弹射器数量研究

为明确大型舰船飞行甲板弹射器数量设计的理论依据,从调运指挥官的角度提出了"虚拟队列"概念,分析了其工作特点,对其工作模式进行了排队论建模.同时分析、建立了舰载机在弹射等待过程中的真实排队模型.忽略其它甲板因素的影响,基于排队论假设代入数值计算了不同弹射器数量对虚拟队列中舰载机的等待队长、系统等待耗时等关键指标的影响,使...     

Application of El Farol model for managing marine terminal gate congestion

Truck queuing at marine terminal gates has long been recognized as a source of emissions problem due to the large number of trucks idling. For this reason, there is a great deal of interest among the different stakeholders to lessen the severity of the problem. An approach being experimented by some terminals to reduce truck queuing at the terminal is to provide live views of their gates via webcams. An assumption made by the terminals in this method is that truck dispatchers and drivers will make rational decisions regarding their departure times such that there will be less fluctuations in truck arrivals at the terminal based on the live information. However, it is clear that if dispatchers send trucks to the terminal whenever the truck queues are short and not send trucks when the truck queues are long, it could lead to a perpetual whip lash effect. This study explores the predictive strategies that need to be made by the various dispatchers to achieve the desired effects (i.e. steady arrival of trucks and hence less queuing at the seaport terminal gates). This problem is studied with the use of an agent-based simulation model and the solution to the well known El Farol Bar problem. Results demonstrate that truck depots can manage (without any collaboration with one another) to minimize congestion at seaport terminal gates by using the provided real-time gate congestion information and some simple logics for estimating the expected truck wait time.