温拌沥青胶浆流变性能研究

文章通过动态剪切流变试验,分析了投料顺序、温拌剂类型与掺量以及粉胶比对温拌沥青胶浆流变性能的影响。结果表明:矿粉与温拌剂的添加顺序对温拌沥青胶浆的流变性能基本没有影响;SBS改性沥青在一定温度范围内表现出与基质沥青相反的粘弹性规律;Sasobit温拌剂增加了温拌沥青胶浆弹性成分比例,且不同掺量对胶浆流变性能影响不大,3G温拌剂则对胶浆流变性能影响较小;随着粉胶比的增大,温拌沥青胶浆的高温性能与感温性能得到改善。     

温拌沥青胶浆高温性能研究

为确定各种因素对温拌沥青高温性能的影响,文章基于DSR试验研究投料次序、沥青类型、温度及粉胶比对温拌沥青胶浆性能的影响。结果表明:投料次序对温拌沥青胶浆性能影响不大,室内温拌沥青胶浆可通过分次投料后采用玻璃棒搅拌制备;沥青类型对温拌沥青胶浆性能影响明显,温拌改性沥青胶浆的高温性能更佳;高粉胶比的温拌沥青胶浆具备更好的抗车辙能力;温度对温拌沥青胶浆的流动性能影响显著。     

适应潮湿炎热气候的SBS改性沥青混合料高温稳定性评价

文章对SBS掺量为6%的改性沥青混合料AC-16和基质沥青混合料进行马歇尔稳定度试验和车辙试验对比,分析沥青混合料的高温抗车辙性能。结果表明:随着温度升高,沥青混合料的稳定度下降,但SBS改性沥青混合料稳定度的降低速度低于基质沥青混合料;在沥青混合料试样DS动稳定度不断增加时,RD车辙深度和车辙变形的时间累计A表现为不断缩小,SBS改性沥青混合料AC-16的高温性能更适于广西高温潮湿多雨的气候特点。     

废旧橡塑复合材料RP2000改性沥青混合料高温性能研究

本文在沥青混合料高温稳定性试验方法研究的基础上,选用典型的三种骨架结构的级配进行对比分析,研究了不同级配类型沥青混合料掺加RP2000抗车辙剂后高温性能变化规律。同时对RP2000与不同种类的抗车辙剂沥青混合料、基质沥青混合料和SBS改性沥青混合料的高温性能进行对比。     

油页岩废渣沥青混合料的性能研究

在道路工程中,油页岩废渣沥青混合料的配比将会直接影响到混合料的整体性能.文章通过车辙试验、劈裂试验以及浸水马歇尔试验,对油页岩废渣沥青混合料的性能进行研究,并将试验结果与基质沥青性能与改性沥青性能进行对比分析.研究表明,油页岩废渣沥青混合料综合性能处于基质沥青性能和SBS改性沥青性能之间,可以作为油页岩废渣的一种再利用...     

SBS改性剂对改性沥青性能的影响现状分析

SBS改性沥青是我国高速公路沥青路面最重要的改性形式,文章对比讨论了SBS改性剂种类、SBS改性剂结构以及原材料老化对SBS改性沥青性能的影响,并分析了某省90#进口沥青组分多年变化情况,说明了控制加工改性沥青原材料质量对确保改性沥青质量至关重要。     

Buton岩改性沥青及沥青混合料的路用性能研究

文章采用动态力学分析了不同掺配比例下的布敦（Buton）岩改性沥青混合料的路用性能,并通过高温性能试验,得出了车辙因子G＊/sinδ与沥青混合料动稳定度具有较好的相关性,可作为评价Buton改性沥青高温性能的指标,预估沥青混合料的抗车辙能力。     

基于路用性能的SBS改性沥青混合料再生方式影响分析

文章以路用性能为控制指标,采用70^#、90^#基质沥青替代SBS改性沥青,拟定4种混合料再生方案,成型相应的再生SBS改性沥青混合料试件组,通过高温车辙试验、低温小梁弯曲试验以及水稳定性冻融劈裂试验,开展基于路用性能的SBS改性沥青混合料再生方式影响分析。试验结果表明：随着RAP掺配比例提升,再生沥青混合料路用性能均显著变化;方案D对应试件组的低温抗裂性表现最佳;方案C对应试件组的水稳定性表现最佳;4类再生方案对应的最大RAP掺配比例分别为38.8%、36.5%、44.2%、46.7%。研究成果可为不同应用场景的SBS改性沥青混合料再生利用提供借鉴。     

脱油沥青与SBS复合改性沥青高温性能研究

文章采用脱油沥青和SBS制备一种新型的复合改性沥青,以期充分发挥两者的优势,同时避免单掺时的缺点,为我国沥青路面高温车辙病害等问题提供一种新的解决思路。结果表明:不同种类脱油沥青的掺入均能提高改性沥青的高温性能,随着脱油沥青掺量或SBS掺量的增加,改性沥青的软化点、135℃旋转黏度及76℃车辙因子随之增大,沥青混合料AC-13的60℃动稳定度也增大,高温性能明显改善;最终优选出高温性能优良且技术经济性优势明显的脱油沥青与SBS复合改性沥青,其配方为:基质沥青:脱油沥青C:SBS=100%∶30%∶4%。     

SBS改性沥青路面施工技术探讨

SBS改性沥青具有良好的抗车辙能力,在高级公路、城市公路以及机场跑道都得到了很好的应用。结合江苏省徐州市内某条公路施工经验,从SBS沥青混合料的配合比设计、SBS沥青混合料的运输、拌和、摊铺等方面分析了SBS改性沥青路面施工技术的要求,可为相关施工提供参考。     

Survey of R&D in PRT systems

A survey of research and development in advanced transit has been made by Chalmers University of Technology in Gothenburg in cooperation with Trans21 in Boston. Summary findings are reported for fourteen academic research programs and ten development programs for PRT. An earlier version of this paper was presented at the International Conference of PRT and other Emerging Systems held in Minneapolis in 1996.     

The Impact of Container Type Diversification on Regional British Port Development Strategies

Abstract

Despite a concentration of container traffic in the southeast of the UK over the last few decades, regional ports are attempting new development strategies to capture or retain specific traffic segments. These include intra-European short-sea traffic and a potentially increasing feeder market. These trends are reflected in the movement of different container types, which result in a number of planning challenges related to changing infrastructural and operational requirements. This paper uses highly disaggregated data on container type movements to address three issues that can inform these planning challenges. First, the imbalance of trade resulting in empty container repositioning; second, the requirement for gauge-cleared rail routes to cater for the increasing proportion of high-cube containers; and third, the specialisation of European short-sea traffic at secondary UK ports. The results reveal the disproportionate repositioning of empty containers at Scottish ports and the importance of 45?ft, high-cube and pallet-wide containers at regional ports, highlighting their focus on intra-European short-sea traffic and raising difficulties relating to their lower quality of landside infrastructure (particularly rail) in comparison to the large south-eastern ports. The potential repercussions on hinterland infrastructure development raise questions about both public and private sector responses to regional port development.     

管道风险分析指数评分法中分值调整初探

管道风险分析指数评分法中重要步骤之一就是确定影响管道事故因素的权重,各个管道风险因素在整个管道事故中所占的权重是不相同的。针对目前管道风险分析指数评分法基本假设之一（各因素的分值范围都是0～100分）,为了更加客观、准确、合理地反映各个风险因素对于管道事故的影响程度,提出并论述了依据层次分析法的数学逻辑性进行综合计算得出管道风险因素的权重,然后对评分法中各个因素的最高分值,根据其权重不同进行相应调整,从而增强评价者对风险因素的认识和评判能力,提高管道风险评价结果的准确性。     

A century of evolution of the accessibility concept

The concept of accessibility has acquired numerous meanings along multiple dimensions during the century of its evolution. This essay argues for the salience of two dimensions: application-based and definition-based. In its application, accessibility has incorporated positive and normative dimensions which have varied in prominence over time. In its definition, accessibility has varied between a mode of evaluation incorporating measured mobility and proximity, on the one hand, and a predefined market basket of urbanist improvements to transportation and land use systems, on the other. Advocates of the accessibility shift should emphasize both the measured approach to accessibility and accessibility’s normative side.     

天然气站往复式压缩机活塞失效分析

针对天然气站往复式压缩机活塞的断裂事故,运用失效分析方法,开展了活塞断口扫描电镜分析、能谱和金相分析。根据断口形貌的电镜和金相观察结果,结合理论知识,分析确定了该活塞发生断裂事故的主要原因,即在特定工况下该活塞的材料缺陷是造成断裂的主要因素。     

中国城市道路规划方位性问题研究

文章结合中国的传统建筑文化理念和现代科学原理,从历史文化、能源节约、环境保护、房地产定价、交通安全等多方面分析研究了城市道路在规划和设计时所应遵从的定向规则。     

Planning guidelines for metro–bus interchanges by means of a pedestrian microsimulation model

The big paradigm for cities nowadays is to study the movement of pedestrians at the interface between metro and bus systems – metro–bus interchanges. When these interchanges are not well designed, walking is inefficient and can be unsafe for pedestrians. This paper analyses, by means of a pedestrian microsimulation model, metro–bus interchange spaces in order to propose planning guidelines for the city of Santiago de Chile. Specific objectives are (1) to identify the variables that provide efficiency and safety in those spaces; (2) to simulate different scenarios using the pedestrian simulation model LEGION; (3) to propose planning and design guidelines for pedestrian spaces at metro–bus interchanges; and (4) to contrast the recommendations in the recently opened terminal station on Line 1 of Metro de Santiago: Los Dominicos Station.     

Predicting queue variability to enable analysis of overload risk

ABSTRACT

Predicting the risk of traffic demands and delays exceeding critical limits at road junctions, airports, hospitals, etc., requires knowing how both mean and variance of queue size vary over time. Microscopic simulation can explore variability but is computationally demanding and gives only sample results. A computationally efficient approximation to the mean is used in many modelling tools, but only empirical extensions for variance in particular situations have been available. The paper derives theoretical formulae for time-dependent and equilibrium variance, believed to be novel and to apply generally to queues covered by the Pollaczek–Khinchin mean formula, and offering possible structural insights. These are applied in an extended approximation giving mutually consistent mean and variance estimates with improved accuracy. Tests on oversaturated peak demand cases are compared with Markov probabilistic simulation, demonstrating accuracy (R^2?>?0.99) for typical random, priority-like (M/M/1) and traffic-signal-like (M/D/1) queues. Implications for risk analysis, planning and policy are considered.     

生命大过天

文章介绍了广西壮族自治区公路管理局开展专项行动,治理以桥梁为重点的交通基础设施安全隐患的情况,针对在役桥梁、在建桥梁和农村公路桥梁存在的安全隐患提出了相应的治理措施。