中空纤维超滤膜通量影响因素的实验研究

膜分离技术是近年来国内能够对多组分物质进行高效过滤浓缩处理的新兴技术产业,不同的膜进行分离处理的机理是不同的,针对不同的分离组分采用适宜的膜进行分离,膜组件在处理油污水领域具备很大的发展潜力。超滤膜对于处理含油污水具有高效的表现能力,且抗污染的能力较好,故本文采用超滤膜进行船舶营运过程中所产生的含油污水的分离实验,研究中空纤维超滤膜分离过程中的膜通量变化的影响因素。     

土压平衡盾构施工污水净化处理技术研究

土压平衡盾构工程施工过程中会产生大量污水,若未经处理直接排放将对周围的环境造成一定的污染。特别是在市区施工,环境保护要求高,施工场地狭小,若采用传统多级平流沉淀池进行污水自然沉淀,已很难满足城市污水排放要求和施工需要。文章针对盾构法施工污水排放问题介绍了一种新的污水净化处理系统,施工污水经过该系统处理后可以直接排放到城市下水道;其处理后的产物——清水,可以循环利用,具有很好的社会经济效益;该系统并具有处理效率高、性价比高等特点。     

宝浪油田污水防腐与防护技术研究(二)

(接上期 )6　防腐措施研究6 .1　主体设备的涂层 牺牲阳极联合保护技术研究6 .1 .1　防腐涂层优选在宝浪油田联合站 ,选用了HY - 0 0 7、H87、环氧树脂等多种不同防腐层进行试验对比。结果表明 :HY -0 0 7不仅能够较好地耐受宝浪油田含油污水的浸蚀 ,并且附着力、柔韧性均较好     

兼氧—好氧—物化工艺处理服务区高氨氮废水

通过对浙江省高速公路30对服务区污水处理方案的调查,及对沪杭甬和杭金衢高速部分服务区污水取样研究,针对污水氨氮浓度高的特点,采用兼氧-好氧-物化的组合工艺来处理这类污水,研究结果表明,污水的各项指标均能达到国家一级排放标准。经核算,该工艺每吨水的处理成本约为0.58元,经济和环境效益十分显著。     

高速公路服务区生活污水特征及其处理工艺研究进展

聚焦于我国高速公路服务区的生活污水,由于服务区车辆随机性大,从而污水具有水量、水质变化波动大的特征,并将其与常规生活污水作对比,可以得出高速公路服务区污水浓度更高,成分更复杂,处理难度更大。针对此污水详细介绍了目前普遍采用的四种组合工艺,分别是生物接触氧化法+沉淀工艺、AO+MBR工艺、生物预处理+人工湿地、生物滤池工艺,并对四种工艺从处理效果、建设成本、运行成本、可操作性以及不同工艺的缺点上进行了比较分析。最后文章针对污水资源化利用的可行性,从水质和经济上进行了分析,将中水回用于绿化、冲厕等用途是高速公路服务区污水资源化利用的有效途径,不仅保护周围环境,节约服务区运营成本,同时可实现经济和环境效益。     

大窑湾港区污水收集与处理系统方案研究

大窑湾港区因建设年代、自然条件和生产经营性质影响,导致其污水收集、处理过程中存在雨污部分、管网渗漏、海水入侵、水质超标及设备运行不稳定等问题.本文以优化和改善大窑湾港区污水收集与处理系统为目标,通过对区域生产经营、污水产排、管网布设及污水处理设施运行情况进行调研和分析,结合港区实际情况提出适宜的港区污水收集与处理系统改造方案,推动绿色生态港口的建设.     

加拿大将建全国最大规模污水排放隧道

正加拿大将建造全国最大规模的污水排放隧道,灰桥湾(Ashbridges Bay)污水处理厂处理过的污水将通过隧道全部排放至安大略湖。新的排污隧道建成后,将取代过去的老旧排污水管,并将成为加拿大境内最大的污水排放管道,每天可排放大约10.4亿加仑(约39亿L)污水。工程包括1个位于湖底岩层内长约3.5 km、直径     

大型原油储罐机械清洗热水清洗效率的提升

结合大型原油储罐机械清洗的现状及工艺,针对其热水清洗阶段效率不高的问题,从用水量、喷枪布置及清洗工艺、罐内浮油的抽吸效率、含油污水的油水分离效率等方面进行分析;通过设计安装抽吸辅助装置、温水射流装置等新装置,提出基于抽吸口位置的喷枪布置方案和清洗工艺,有针对性地控制清洗温度;减少了用水量及循环清洗次数,提高了罐内浮油的抽吸效率和油水分离效率。在实际作业中有效提高了热水清洗效率,节约作业时间2/3以上。     

上海市白龙港污水排放系统中线西段工程的设计探讨

白龙港污水排放系统中线西段工程是将浦西黄浦区市中心的污水截流纳入到污水治理二期工程，输送到白龙港预处理后，外排长江。工程涉及到五座旧泵站的截流改建，截流管、过黄浦江倒虹管、中途提升泵站的设计，是一项内容较为全面的污水系统工程。通过对设计要点和难点的介绍与探讨，为今后同类工程的设计提供参考。     

关于防污染系统的一些建议

笔者用实践经验,在文章中阐述了新造船怎样采用新技术、新工艺,做到油污水容易处理,油渣可连续燃烧,实现防污染系统设备的实用性和可操作性。     

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.     

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.     

Governing autonomous vehicles: emerging responses for safety,liability, privacy,cybersecurity, and industry risks

ABSTRACT

The benefits of autonomous vehicles (AVs) are widely acknowledged, but there are concerns about the extent of these benefits and AV risks and unintended consequences. In this article, we first examine AVs and different categories of the technological risks associated with them. We then explore strategies that can be adopted to address these risks, and explore emerging responses by governments for addressing AV risks. Our analyses reveal that, thus far, governments have in most instances avoided stringent measures in order to promote AV developments and the majority of responses are non-binding and focus on creating councils or working groups to better explore AV implications. The US has been active in introducing legislations to address issues related to privacy and cybersecurity. The UK and Germany, in particular, have enacted laws to address liability issues; other countries mostly acknowledge these issues, but have yet to implement specific strategies. To address privacy and cybersecurity risks strategies ranging from introduction or amendment of non-AV specific legislation to creating working groups have been adopted. Much less attention has been paid to issues such as environmental and employment risks, although a few governments have begun programmes to retrain workers who might be negatively affected.     

Real-world gaseous and particle emissions of a Bi-fuel gasoline/CNG Euro 6 passenger car

The objective of the present study is the assessment of the environmental impact of a bivalent (bi-fuel) vehicle, running either on gasoline or compressed natural gas (CNG). To that aim, a Euro 6 passenger car was tested under various real-world driving conditions. In order to cover the full range of conventional powertrains currently in the market, the tests were also repeated on a Euro 6 diesel passenger car. Both cars were driven in two routes, the first complying with the regulation limits and the second going beyond them. Carbon monoxide (CO), nitrogen oxides (NO_x) and particle number (PN) emissions were recorded using a Portable Emissions Measurement System (PEMS). Apart from the aggregated emission levels, in g/km, the exact emission location along the route was also assessed. Natural gas proved beneficial for CO and PN emissions, the level of which always remained below the respective legislation limits. On the other hand, under the dynamic driving conditions with gasoline, the relevant limits were exceeded. Cold start, occurring at the beginning of the urban part, and motorway driving were identified as major contributors to total emissions, especially in gasoline mode. However, the application of natural gas was associated with a penalty in NO_x emissions, which were significantly increased as compared to gasoline. Local peaks within the urban part were identified in CNG mode. In any case, the diesel vehicle was by far the highest NO_x emitter.