城镇燃气管道腐蚀检测案例分析

为优化城镇燃气管道的防腐措施，提高钢质管道的防腐效率，通过对某燃气公司城镇燃气管道检测中发现的典型腐蚀案例分析，找出了其腐蚀形态主要有土壤电化学腐蚀、微生物腐蚀、杂散电流腐蚀等，总结出可采取的防腐措施有管道外壁加装防腐层、安装阴极保护设施、增设排流装置等。对检测中发现的腐蚀缺陷，采用局部挖补、防腐层补口、接地排流技术处理，运行结果表明：修复后的管道阴极保护参数测试正常，土壤表面电位梯度0.4 mV/m,管地电位正向偏移值35 mV,无防腐层损坏、剥离及杂散电流腐蚀现象，解决了该条管道的防腐控制问题。     

油气站场埋地管网腐蚀控制技术

介绍了国内外站场管道的腐蚀情况,并分别从防腐层、区域性阴极保护、在线监/检测角度进一步对比分析了国内外油气站场埋地管道的腐蚀控制情况;从防腐层和阴极保护两方面总结了站场埋地管道腐蚀的主要原因,制订了相应的腐蚀控制对策;并根据国内站场腐蚀的具体情况,从表面处理、防腐材料性能指标、防腐层结构和防腐等级设计几方面对优化站场管道防腐层提出了相应的建议.     

对埋地金属管道外防腐的几点认识

简要介绍了大庆油田埋地管道腐蚀和防腐材料现状,对埋地管道外腐蚀原因并针对外防腐结构外选材的不合理性,更新改造工程的“以换代修”等问题进行了分析,为提高埋地管道外防腐工程质量,建议根据管道工程实际条件,对外防腐方案进行了分的技术经济论证,并应尽快制定旧管道更换和维修标准及界限,加强长输管道外防腐的几评价等工作。     

原油长输防腐保温管预制质量的影响因素分析

防腐保温管的预制质量是影响整个原油管道工程质量的关键因素之一,保证防腐保温管的预制质量至关重要。结合对现场埋地管道硬质聚氨酯泡沫防腐保温层的失效原因分析,通过对现场聚氨酯防腐保温管生产工艺的研究,重点对聚乙烯外护管挤出工艺、穿管工艺、聚氨酯发泡工艺进行了分析,总结了原油长输防腐保温管"两步法"预制过程和储存、运输中的质量影响因素,研究成果对提高油气长输防腐保温管道预制质量具有积极作用。     

输油管道腐蚀控制及防腐层大修技术

文中总结了引起输油管道局部腐蚀的主要原因,结合实例详细分析了输油管道在水泥固定管墩中及管道在穿跨越公路、铁路、河流的套管中引起腐蚀的几种原因,并提出了在水泥固定墩和套管中腐蚀控制应注意的问题及采取的措施,介绍了输油管道防腐层大修工艺和质量控制措施,结合实际案例介绍了防腐层大修技术的实际应用,为相关专业人士提供了参考。     

保温管道保温层进水监测技术现状

针对石油、化工行业中保温管道由于保温层进水导致腐蚀的问题,总结分析了保温管道保温层下腐蚀原因及机理。介绍了红外热成像技术、分布式光纤技术、基于金属电位差监测技术在保温层进水监测的应用,并针对各项技术的原理、适用性以及应用范围进行总结,为监测保温管道保温层进水情况提供参考。     

浅谈工业水管道内壁腐蚀及砂浆防腐的经济性

针对大庆石油化工总厂埋地给水管道未防腐的内壁腐蚀严重，进行了腐蚀原理分析，提出防腐的必要性。同时对管道内壁采用砂浆衬里的合理性进行了分析，通过该衬里与涂料防腐层的可行性对比。说明采用砂浆衬里对给水管道内防腐是优先选用的方法，其综合效益是相对最好的。     

管道防腐保温技术综述

对输油管线防腐保温是降低能耗、保证管道安全运行的重要手段之一。本文综述了国内外管道防腐保温技术，并对各种防腐保温材料的特性及其应用进行了详尽的论述。     

管道防腐涂层的现状与展望

管道的腐蚀问题是影响管道系统可靠性及使用寿命的关键因素,选择和使用合理的防腐涂层,对管道的安全运行、使用寿命及降低经济成本都具有十分重要的意义。文中简述了管道腐蚀产生的原因,综述了管道防腐涂层的发展概况,着重介绍了液态聚氨酯防腐涂料、无机非金属防腐层、纳米改性材料涂层等管道防腐涂层技术的新发展,提出了这些涂层在管道防腐应用中存在的问题,并对管道防腐涂层的发展前景做了展望。     

输油站场管道腐蚀调查与分析

输油气站场管道敷设复杂,且多数没有实施区域性阴极保护,存在腐蚀风险。选择输油气站场典型腐蚀调查点,通过外观检查、厚度测试、漏点检测、粘结力测试及缺陷点活性评价,对某输油站场防腐层、保温层性能及管道腐蚀情况进行调查。结果表明：生产区管道防腐层失效严重,管体腐蚀,最大腐蚀坑深2.18 mm;立管出入土界面也存在腐蚀。文中分析了腐蚀原因,给出了站场维护维修建议。     

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.     

Modular route bus design – A method of meeting transport operation and vehicle manufacturing requirements

This research examines the problem of route bus specification and vehicle manufacturability. In order for bus operators to provide transport services, a range of vehicle configurations must be available from bus manufacturers, generating variety which has a negative impact on the manufacturing process. Larger part inventories, uncontrolled labour tasks and more troublesome maintenance are known impacts of this variety. This research identifies the functional necessities in route bus interior design and reduces the problems in bus manufacture and operation caused by specification diversity by proposing a modularised system of bus design. In particular, it makes recommendations as to how bus configuration should be carried out, ensuring an optimum mix of operational and manufacturing needs:

• 1.Determine user needs before the bus specification process.
• 2.Designs to be developed by the manufacturer in response to user needs.
• 3.This design should be standardised where possible, as suggested by the user needs.
• 4.Where user needs dictate product variations, apply a mass customisation approach to accommodate these needs.

The recommendations are communicated in design proposals for a modular bus interior, demonstrated by four cases designed to meet the present status quo of bus interior design and predictions for the future of the field.     

Optimization of bus stop locations for improving transit accessibility

A mathematical model is developed in this paper to improve the accessibility of a bus service. To formulate the optimization model, a segment of a bus route is given, on which a number of demand entry points are distributed realistically. The objective total cost function (i.e. the sum of supplier and user costs) is minimized by optimizing the number and locations of stops, subject to non‐additive users' value of time. A numerical example is designed to demonstrate the effectiveness of the method thus developed to optimize the bus stop location problem. The sensitivity of the total cost to various parameters (e.g. value of users' time, access speed, and demand density) and the effect of the parameters on the optimal stop locations are analyzed and discussed.     

Productive efficiency and ownership of urban bus services

The established ownership mix of urban bus operations in Australia provides a unique opportunity to investigate the productivity differences between public and private bus service supply. Using duality theory in economics which links economic indices of factor productivity to the cost structure of a firm, we develop empirical measures of total and partial productivity of inputs, and adjust the differences for the effects of ownership status and operating environment. The evidence supports the notion that private supply of public passenger transport in general has performed more efficiently in the past than public supply, although the differences in productivity need not continue in the future.     

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。     

Determinants of modal choice in freight transport

In the next few years, exciting developments in the field of freight transport are likely to occur. The Channel Tunnel will be perceived as giving railways much greater distance of operation, compared to the current train ferry to/from Great Britain. The further development of swap-body technology will allow easier modal transfer and the creation, in 1992, of a single market in Europe will transform the pattern of trade. All of these are likely to have significant impacts on modal choice, and hence modal split, in freight transport. Reappraisal by many firms of the modes of transport used is likely but will it result in a net transfer of freight from road to rail and, if so, to what extent? To answer such questions, an accurate and reliable method of predicting modal split is required. Research in the past has concentrated on the development of modal split models based on generalised costs. These fail to explain adequately the prevalence of road freight in the UK. From surveys of freight managers within industry, it is clear that models to date rely too heavily on the economic cost factor and too little on behavioural factors (Jeffs 1985). This paper derives from a recent study of freight transport modal choice from the standpoint of the transport decision-maker within the firm. It attempts to shed light on the actual parameters which should be incorporated into a modal split model. Many variables appear to exert an influence on modal choice decision-making process. However, it is possible to categorise them into six main groups, namely: customer-requirements; product-characteristics; company structure/organisation; government interventions; available transport facilities; and perceptions of the decision-maker him/herself. It is the interactions and inter-relationships between these which ultimately determine freight modal split. This study has shown that the relationship between the outcome of the transport decision process and the values of particular determinants of modal split is not straight-forward, due to the complexity and variety of interactions involved. Perhaps one of the main reasons for researchers' failure hitherto to develop a successful modal-split model has been the preoccupation with techniques that rely on the development of common metric (e.g. generalised cost), which has led to the exclusion of some important explanatory variables along quite different dimensions. Another important issue concerns the appropriate level of aggregation. In order not to reduce the explanatory power of the key variables, it is important to work at a disaggregate level, although this does make substantial demands on data. The use of factor analysis enables both the aggregation of information without loss of behavioural reality and the specification of variables in terms of a common metric. In conclusion, freight transport has usually been examined within too narrow a framework. It must be placed firmly within the context of the total industrial process. The demand for freight transport is directly influenced by the level, composition and geographical distribution of production and consumption activities. Freight flows are complex and so it is highly unlikely that a universal mode-choice model can ever be developed. Future research should, therefore, be directed towards developing partial models in response to specific needs of those involved in decision-taking in the freight sector.     

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。