甲醇汽油发动机应用性能研究

本文从动力性、经济性和排放特性等方面对客车甲醇汽油发动机的应用进行了分析,并且对甲醇汽油应用所存在的问题进行了研究,通过对比分析得出:甲醇汽油较纯汽油相比,发动机动力性不下降,燃料消耗量增加,HC和CO排放降低,经过双三元催化转换器后,甲醛的排放达到与纯汽油发动机相同的水平。     

汽油清净剂的研究与应用

社会可持续发展向汽车和发动机燃料提出了环保与节能的严格要求。本文介绍了国内外汽油清净剂的发展历史和现状,概述了汽油清净剂的作用机理,通过试验结果表明:汽油清净剂具有抑制和清除发动机沉积物的作用,可大大改善起动性能,同时在一定程度上可以降低排放。最后对我国汽油清净剂的推广和应用提出了建议。     

车用转子发动机性能分析

阐述了转子发动机的结构和工作原理,说明了气缸型线和三角转子外廓的形成机理和结构参数.分析了转子发动机的动力性、燃油经济性、排放性及转子发动机应用中存在的问题和发展前景.     

发动机无法启动常见故障分析

每一台汽油发动机的启动和运转均需要火花、燃油和压缩。当发动机不启动时,有计划的诊断步骤将帮助我们迅速确定故障的原因。本文中,将说明如何采取有计划的诊断步骤对发动机无法启动的故障进行诊断,并将解释为什么围绕基本的因素能使故障诊断工作完成得更快。汽油发动机的故障及诊断方法为:1.起动电路对于不启动故障的诊断一般总是从起动电路开始。一般的起动电路主要由蓄电池、起动机和电缆组成,这里只介绍蓄电池故障检测。蓄电池故障将是任何不启动诊断的首检目标。在启动发动机期间,蓄电池的电压是一重要因素。若蓄电池电压下降过低,则使电燃油泵不能达到最佳速度,从而使燃油传送减少;另一方面,下降过低的蓄电池电压,将影响发动机控制模块,该模块进而导致无火花、不传送燃油或导     

钢管与法兰对接环焊缝开裂分析

采用化学成分分析、力学性能检测、宏观及扫描电镜分析等方法对输送管道站场发现的F52法兰与L360/X52 HFW钢管对接环焊缝开裂的原因进行了分析。结果表明:F52法兰含碳量偏高、焊接性差是导致法兰侧热影响区产生冷裂纹的主要内因,现场焊接工艺及实施过程控制不当是裂纹产生的主要诱因。采取以焊接性较差的一侧确定焊接工艺及焊前预热措施后,该类现象再未发生过。     

氮气储罐用钢Q370R的焊接工艺

氮气储罐的设计材料为低合金高强钢Q370R。通过焊接性分析,Q370R有冷裂纹倾向,没有热裂纹和再热裂纹倾向。Q370R碳当量一般为0.42%左右,有淬硬倾向,应焊前预热。当钢板厚度超过32 mm时,焊接拘束应力增大,应进行焊后消除应力热处理。根据等强度原则选择埋弧焊焊丝H08Mn Mo A和焊条J557R做为焊接材料分别进行的焊接工艺评定的各项力学性能合格,以焊接工艺评定获得的工艺参数焊接的氮气储罐完全达到了设计要求。     

速腾轿车蓄电池自行放电故障检测与分析

蓄电池是汽车的重要电源,起动发动机时,给起动系统、点火系统、电子燃油喷射系统及其他电气设备供电。汽车上的蓄电池,必须满足起动发动机的需要,即在5~10s的短时间内,提供汽车起动机足够大的电流。汽车蓄电池一旦自放电过大,就会影响到汽车的启动,因此,必须查出放电的原因,彻底排除故障。     

完善甲醇汽车使用技术的研究方向及技术方案

目前,真正实现甲醇燃料能够在发动机及车辆正常使用,必须从燃料消耗的替比率、动力输出、日常维护费用等诸多方面,达到同使用汽油燃料相比,一个性能稳定而方便,燃料消耗费用低的水平。这一理念的实现,是建立在完善甲醇燃料两大技术系统之上的。一个技术系统是运用合理的燃料添加剂解决甲醇作为替代燃料,改变燃料自身存在的缺陷,使之成为改性甲醇燃料;另一技术系统是开发适用甲醇燃料的发动机辅助设备和日常专用维护产品。这样才能达到经济推广,广泛使用的目的。     

高纯CO2一步法制甲醇工艺中产品酸度偏高原因及控制策略分析

本文综合分析了利用高纯CO₂一步法生产甲醇时所遇到的产品酸度偏高的问题。首先介绍了甲醇的传统生产方法和高纯CO₂一步法的工艺流程。接着详细探讨了甲醇产品中酸度偏高的影响因素,包括粗醇中酸性气体的带入、塔操作不当以及系统串气问题。根据这些因素,提出了一系列改进措施和建议,以期降低产品中的酸度,提高甲醇的质量。本文旨在为相关工艺的优化和产品质量的控制提供理论依据和实践指导。     

埋地热油管道正向预热过程的计算与分析

埋地热油管道预热过程是一个不稳定传热过程,埋地热油管道启输过程的土壤温度场是一个沿管道横断面（径向和切向）与轴向的三维非稳态传热问题。通过分析埋地热油管道的几何特性,考虑了沿轴向预热介质温降对土壤温度变化的影响,对埋地热油管线正常运行和正向预热过程时的数学模型进行了适当的简化和处理,并且对正向预热时土壤蓄热量进行了计算,还利用数值计算的方法进行了求解,得到了油温在轴向和径向上的变化规律,在求解数学模型时,对某一断面处的土壤部分的温度场应用有限差分法求解。     

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.     

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.     

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.     

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.     

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。     

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。     

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.