Aggregation and travel time calculation over large scale traffic networks: An empiric study on the Grenoble City

In this paper we consider aggregation technique to reduce the complexity of large-scale traffic network. In particular, we consider the city of Grenoble and show that, by clustering adjacent sections based on a similarity of speed condition, it is possible to cut down the complexity of the network without loosing crucial and intrinsic information. To this end, we consider travel time computation as a metric of comparison between the original graph and the reduced one: for each cluster we define four attributes (average speed, primary and secondary length and heading) and show that, in case of an aggregation rate of 95%, these attributes are sufficient in order to maintain the travel time error below the 25%.     

邮轮空调通风生产设计过程管理

借助管理学中的行为触点图分析方法,对邮轮空调通风生产设计过程中典型的风管建模、设备定义工作进行痛点分析,结果表明,在邮轮空调通风生产设计过程中的技术管理方面,重点在于输入条件和输出反馈;在计划管理方面,需确保结构风道、舾装风管、设备定义的协同设计工作有序进行;在人才管理方面,应在科学评估设计工时的基础上合理配置人力,提...     

高速铁路接触线不平顺线谱研究

功率谱密度函数可以从波长和幅值两方面反应接触线不平顺的特征和规律,是研究接触线不平顺状态的重要工具。本文以我国多条高速铁路线路的接触线垂向不平顺实测数据为基础,采用最大熵谱估计得到接触线不平顺实测功率谱,并提出一种普适性强、结构简单的不平顺线谱模型。研究结果表明:我国高速铁路线路的PSD最值均小于0.01m2/m-1,接触线整体不平顺状态较好;随机不平顺中含有的周期性简谐波成分,波长主要为单倍跨距和单倍吊弦距;文中建立的接触线不平顺线谱新模型参数少、普适性强、拟合效果优,并给出该模型参数的非线性最小二乘估算结果。     

考虑实测轮载的动态模量加载波形及荷载作用时间取值研究

利用三维有限元计算工具,考虑沥青路面结构层不同的模量和厚度组合,结合实测的竖向轮胎-路面接地压力并考虑水平作用力,分析沥青路面结构层不同深度处的竖向应力脉冲波形.分析结果表明:同一沥青路面结构层不同深度处,不仅其竖向应力脉冲波形不相同,波长也不一样;也就是说,对同一路面结构不同深度处动态模量的确定,除了需要考虑不同的实验室加载波形和加载频率以外,还需要对荷载作用时间的取值做出修正.     

卫星网络设备调度仿真平台设计研究

在卫星网络中每一个卫星节点的负载设备不断测量采集数据,并通过中继节点进行转发,根据任务要求调度星载设备并进行路由是当前的研究重点问题。因此需要建立一种仿真工具,能够对卫星通信链路、路由策略以及调度算法进行模拟和性能评估。为此提出了该仿真系统的体系结构及其设计思想,并论述了系统中采用的关键技术,包括星间路由、设备负载调度以及信道仿真算法等。最后给出了一个典型仿真脚本的实验数据。     

基于ANSYS的沉箱吊孔应力接触分析

重力式码头或直立式护岸施工中,沉箱吊运安装是一种常见的施工工艺。通过ANSYS有限元软件建立吊孔及起重销三维模型,设置合理的接触对和边界条件,利用其接触分析功能对某直立式护岸工程的沉箱吊孔应力进行分析。得到了吊运过程中吊孔附近的应力分布规律,并提出了吊孔局部受压净面积的计算方法,可为其它类似工程提供参考。     

Hub location in the South-Atlantic airline market: A spatial competition game

The paper analyzes the airlines’ hub location problem through a spatial competition game played in two stages. First, airlines sequentially choose the location of their hub and second, they compete offering direct or connecting services between each city-pair. Different outcomes in the first stage will affect competition in the second, and as a consequence, the market share that airlines can obtain.Given actual demand patterns, results of the model are applied to the South-Atlantic airline market. We study the subgame perfect equilibriums obtained as a result of competition in each city-pair to anticipate where airlines will probably locate their hubs once an “open skies” policy is adopted in this market.     

Assessment of economic impacts from unexpected events with an interregional commodity flow and multimodal transportation network model

Loss and damage caused by unscheduled events, especially earthquakes, have sudden and significant impacts not only on the region’s economy where the event occurs but also on other regions. The New Madrid Seismic Zone, located in the center of the United States, could have great impacts on economic activities related to this area, if a major earthquake occurred. Based on the 1993 US Commodity Flow Survey [US Commodity Flow Survey, 1993. Available from: <http://www.bts.gov/ntda/cfs/prod.html>], more than 42% of total commodity flows in the US are related to the greater Midwest, which includes the New Madrid Seismic Zone. If a catastrophic earthquake occurred in this area, the indirect damages could spread far beyond the region, and could have sizable impacts on other regions. A model of interregional commodity flows, incorporating regional input–output relationships, and the corresponding transportation network flows, was applied to assess the economic impacts of such an unexpected event. The economic impacts from the event are described for three hypothetical scenarios, analyzing the magnitude and the extent of the direct and indirect impacts. These analytical results may be used to propose strategic management of the recovery and reconstruction efforts after the event.     

VxWorks环境下组合导航实时通讯软件的设计

针对组合导航系统的具体组成结构，提出了组合导航系统实时通讯的具体要求。在分析了VxWorks的多任务环境和中断特点后，利用TCP／IP协议支持的套接字实现了网络通讯编程，利用VxW池提供网络函数实现了双网卡冗余备份，完成了基于VxWorks的组合导航实时通讯软件的设计。     

钢轨波浪形磨损研究

钢轨波浪形磨损（简称钢轨波磨）是车辆与轨道结构激烈振动并产生噪声的主要因素之一，不仅影响旅客乘坐舒适度和装运货物的完好，而且缩短结构部件的使用寿命。结合试验，采用车辆一轨道耦合动力学理论、轮轨三维非赫兹滚动接触理论、材料摩擦磨损理论和塑性理论，研究钢轨波浪形磨损的形成和发展机理。主要研究内容如下。