Multi-objective optimization for asphalt pavement maintenance plans at project level: Integrating performance,cost and environment

Traditionally, asphalt pavement maintenance mainly considers pavement performance and cost and largely ignores the environment while substantial amount of environmental burdens are released in the process. In this study, a multi-objective optimization model was developed integrating the three elements in order to optimize the asphalt pavement maintenance plans at the project level. Pavement performance element was decided as the multiplier of pavement serviceability index and traffic volume. Cost element was represented by the net present value, including components of agency cost, vehicle operation cost and salvage value. Environmental element, integrating energy consumption, global warming potential, acidification potential and respiratory effects potential, was measured by the life cycle assessment model. A hypothetic asphalt pavement maintenance case study was conducted using the developed multi-objective optimization model and harvested 103 sets of feasible combinations of maintenance plans, each of which is non-dominated by the others. Trade-offs analysis was performed among the three objectives and visualized in both two- and three-dimension forms. It is found there is an opportunity of reducing the cost and environmental impacts to 80.3% and 77.8% and increasing the pavement performance to 146.6% compared to the base case. However, they are mutually compromised and cannot be reached simultaneously. The developed model reveals the quantitatively interactive relationship of the three objectives and helps optimize the asphalt pavement maintenance plans.     

基于实例的船舶靠泊操纵技术探讨

船舶靠泊码头操作是驾驶员经常性经历的工作之一,也是操船中事故发生率较高的一项操作.以3个码头靠泊时的体会出发,从制定靠泊计划、了解码头情况、熟知本船性能和控制余速4个方面,进一步总结船舶靠泊码头应注意的事项.     

扣件DI弹条非正常部位断裂原因分析及结构优化

通过对DI弹条非正常部位断裂的研究,发现扣件安装时弹条与铁垫板安装孔发生接触,致使弹条在中肢与尾部圆弧过渡区域产生应力集中,发生早期疲劳断裂。本文在研究弹条结构及安装方式的基础上,在弹条的中肢与尾部圆弧过渡区域引入"凹面"结构,对弹条进行结构优化,并通过扣压力和疲劳性能检测、实验室疲劳断裂检验、现场试铺检验等对带有优化"凹面"结构的DI弹条性能进行检测。结果表明:优化后的弹条扣压力和疲劳性能均合格,且能有效抑制因接触产生的非正常部位断裂,提高弹条性能。     

基于数据驱动的机场水泥混凝土道面性能退化预测

针对机场道面性能退化过程的精确预测问题，本文采用数据驱动的机场道面预测性维护方法，通过指示变量将两种数据集进行联合分析，考虑机场道面性能退化过程受飞行交通量和道面面层厚度的影响，以机场道面性能状况指数衰变的非线性函数为期望函数，建立一种机场道面性能退化双参数预测模型；根据模型的参数估计结果，采用边际效应分析结合预测性能曲线图示，对不同飞行交通量水平和不同道面厚度等级的道面性能退化过程预测进行分析。结果表明，采用数据驱动和非线性混合效应方法，搭载联合估计技术，能较为显著地提高机场道面性能退化预测的精度和效果。     

高速铁路路基全断面沥青混凝土防水封闭结构

提出1种高速铁路路基全断面沥青混凝土防水封闭结构,基于该结构工作状态,分析其主要功能特性,设计碾压密实高模量沥青混凝土。将全断面沥青混凝土防水封闭结构应用于工程试验段,跟踪监测其服役特性。结果表明:试验段轨道结构及路堤基床动力性能均满足规范限值要求;试验段基床含水量维持在8%~18%,受天气影响小,而邻近的纤维混凝土对照段基床含水量为10%~35%,随天气波动显著;试验段沥青混凝土的吸热作用,使得路肩处基床温度较对照段大;试验段路基竖向变形监测值较对照段稍大,但均满足限值要求;试验段沥青混凝土与底座等接触情况良好,无松散剥落等病害,仅在底座板接缝处有数条裂缝,而对照段出现较多的纵横向裂缝,严重影响其防水封闭效果;沥青混凝土修补方便,可维护性高。     

马来西亚ETS米轨干线动车组概述

文章介绍了马来西亚ETS米轨干线动车组的运行线路及运用环境情况,着重分析了车辆主要技术特点及总体性能参数,详细阐述了其主要机械、电气系统与转向架等的设计方案和技术特点。     

Fully autonomous vehicles: analyzing transportation network performance and operating scenarios in the Greater Toronto Area,Canada

Fully autonomous vehicles (AVs) have the potential to considerably change urban mobility in the future. This study simulates potential AV operating scenarios in the Greater Toronto Area (GTA), Canada, and assesses transportation system performance on a regional level. For each scenario, the base capacities of certain types of road links are modified to simulate the theoretical increase in throughput enabled by AV driving behavior. Another scenario examines driverless parking operations in downtown Toronto. Simulation results indicate that the increased attractiveness of freeways relative to other routes leads to slightly increased average travel distance as vehicles divert to access higher capacity road links. Average travel time is found to decrease by up to one-fifth at the 90% AV market penetration level. Concurrently, localized increases in congestion suggest that proactive transportation planning will be needed to mitigate negative consequences of AV adoption, especially in relation to induced demand for personal automobile travel.     

中国学习者英语搭配和类联结使用探析

本研究基于语料库的数据，分析中国英语学习者在搭配和类联结使用方面的特征。研究发现，学习者在搭配方面表现出搭配行为的不地道性和搭配词使用范围的有限性，学生偏少使用程度副词实现人际功能。通过分析词语所在的类联结及其实现的功能，发现学习者在类联结的使用上和本族语者有显著差异。本文从认知角度讨论搭配和类联接在语言学习中的重要性，认为“注意”有利于学习者掌握搭配和类联接。     

浅谈会计人员委派制

从会计人员委派制的作用出发,剖析了当前会计人员委派制中存在的问题,并据此提出了完善会计人员委派制的具体措施。     

基于SCP理论的我国港口物流绩效定量分析

运用SCP产业组织理论的研究方法,分析我国港口物流产业绩效的整体现状,同时试图构造一个"结构-行为-绩效"的分析框架,为产业现状的科学评价提供服务.研究结果表明:我国港口物流产业目前正处于一种一定程度垄断性质的竞争市场结构;市场行为体现出局部垄断和竞争合作的两重性,其出现的适应性反应,影响了市场结构和市场绩效;另外,市场绩效也造成了产业结构和市场行为的变化.通过技术统计及理论分析,认为我国港口物流产业正处于快速成长时期,其经营绩效显著优于其他物流行业,呈现出较好的发展势头.