The effect of the competition between cars and trucks on the evolution of the motorway transport system

Motorways, which were devised at the beginning of their history as dedicated roads intended to be traveled by cars only, are at present also traveled by considerable flows of trucks. This fact has deeply changed the motorway transport system with respect to its original conception, owing to the interactions between two categories of vehicles whose characteristics are very different. These interactions greatly increase the transport cost perceived by car drivers with respect to truck drivers. This paper studies the consequences of this cost asymmetry on the evolution of the transport system when the geometric characteristics of a motorway remain unchanged in time, while transport demand increases. By using a theoretical model of competition between cars and trucks, it is shown that, if both the geometric characteristics of a motorway and the increase rate of the activities that feed the transport demand remain unchanged over time, the competition between cars and trucks, as well as the fact that in general passengers have better transport alternatives than freight, make the increase rate of truck traffic greater than that of cars, causing a progressive increase in the proportion of trucks in the time periods in which a motorway is traveled by both the vehicle categories. Since truck traffic on motorways, at least in Europe, is very scarce on weekends and in holiday periods, in which motorways are traveled almost only by cars, these results seem to indicate a tendency to the specialization of motorways, which are likely to be used in the future mostly by only one category of vehicles in different periods of time.     

BIM辅助铁路隧道施工方案可视化设计应用

基于BIM技术的3D可视化设计环境和4D虚拟仿真环境,研究BIM辅助施工方案可视化设计和虚拟推演的方法和流程,以及施工方案的环境、结构和施工设施等三维数字模型设计原则。针对铁路隧道仰拱与仰拱填充施工特点,利用BIM辅助施工方案可视化设计,建立施工方案的三维数字模型,优化设计仰拱与仰拱填充快速施工装备与工艺,模拟方案的施工过程。结果表明,BIM辅助铁路隧道施工方案优化设计,取得了很好的效果。     

铁路客专信号产品灌封技术的研究

比较各种灌封材料的优缺点，研究在铁路客专信号产品生产中应用硅树脂凝胶灌封的关键工艺，包括PCBA表面清洁、温度控制、配方管理和控制、抽真空、灌封有效期管理和固化过程管理等，特别提出灌封有效期管理的新观点，并进行实践和总结。     

水下盾构隧道管片钻穿引起的涌水突泥治理技术研究

水下盾构隧道管片钻穿会引起大量涌水突泥，对隧道建设及运营造成重大影响，且采取的隧道修复措施将影响隧道的长期运营安全。以某地铁隧道被意外钻穿的实例为工程背景，为确保水下隧道意外钻穿破坏时，可以做到临时封堵有效，永久修复满足百年使用要求，提出修复思路。在水面利用浮船进行海上袋装水泥封堵，然后筑岛截断隧道与海水的联系； 临时封堵后监测管片变形、复核隧道中线，明确钻孔对隧道限界的影响； 通过计算对结构安全性进行评价，明确钻孔对管片结构受力影响较小。在确保隧道钻穿对隧道限界及结构的影响可控后，采取地面注浆、洞内注浆、倒锥形封堵、洞内设置内撑钢板相结合的方案，对隧道钻穿处进行治理，保证隧道的安全运营。在隧道周边施工时，应加强隧道保护意识，避免对既有隧道造成破坏。     

贵阳机场岩溶洼地填筑体变形与稳定性数值模拟

以贵阳龙洞堡国际机场试验段工程为例对岩溶洼地填筑体变形及稳定性进行数值模拟研究。研究结果表明:强夯对岩溶洼地地基土处理具有较好的效果，能有效降低填筑体的沉降量及边坡位移量；填筑体沉降量随着填筑体厚度减小而减小。     

A multiobjective model for maximizing fleet availability under the presence of flight and maintenance requirements

Every aircraft, military or civilian, must be grounded for maintenance after it has completed a certain number of flight hours since its last maintenance check. In this paper, we address the problem of deciding which available aircraft should fly and for how long, and which grounded aircraft should perform maintenance operations, in a group of aircraft that comprise a combat unit. The objective is to achieve maximum availability of the unit over the planning horizon. We develop a multiobjective optimization model for this problem, and we illustrate its application and solution on a real life instance drawn from the Hellenic Air Force. We also propose two heuristic approaches for solving large scale instances of the problem. We conclude with a discussion that gives insight into the behavior of the model and of the heuristics, based on the analysis of the results obtained.     

基于熵值理论的城市轨道交通投融资结构评价优化

城市轨道交通建设项目中,投融资结构是投融资管理的重要组成部分。从投资管控与融资管理两个角度,设计了城市轨道交通建设项目投融资结构评价指标体系,构建了基于熵值理论的多目标评价模型,对城市轨道交通建设项目投融资结构进行评价分析与优化。并以广州轨道交通11线为应用案例,验证了该评价优化方法的有效性。     

船载集装箱危险货物瞒报谎报行为的证据收集与分析

通过对危险货物瞒报谎报行为的证据收集与分析，提出对该行为调查的方向和基本方法，以供海事执法人员参考。     

靶场试验指挥控制中心系统及其应用

针对靶场试验指挥控制中心的应用需求，介绍靶场试验指挥控制中心系统的功能、特点以及体系结构和组成，分析系统研制的关键技术，说明该系统的应用范围。目前，该指控中心系统已成功地应用于某大型武器系统靶场试验中，取得了较好效果。     

压弯荷载作用下圆截面混凝土桩的损伤分析

运用Lem aitre损伤规律对土木工程中使用的混凝土圆截面桩受压弯荷载下进行损伤分析,推导了无量纲轴向力和无量纲弯矩的表达式,计算了不同失效应变对应的弯矩规律,以及不同失效应变和中性轴的无量纲位移之间的关系。分析结果可作为估算实际工程中混凝土圆截面桩抗弯承载力的参考依据。