磁处理对南海原油凝点的影响规律研究

通过对原油进行磁处理,可以改善原油的流动性,降低其输送成本。通过控制磁化温度、磁化转速和磁化强度,对模拟南海原油油样进行磁处理后凝点变化规律进行了研究。结果表明:磁处理能降低南海原油的凝点,磁化温度、磁化转速和磁化强度对南海原油的凝点均有影响。在40~80℃的温度区间内,磁化温度越高,磁处理降凝效果越好;在0~100 mT的磁场强度范围内,随着磁化强度增加,凝点具有不断降低趋势;最优的磁化转速为1000 r/min,在此转速下,实验油样凝点降低了4.7%。     

河口-沾化输油管道加剂试验研究

河沾线管输原油黏度大，凝固点高，管输困难，为解决此问题，进行了河沾线应用BEM－5P流动性改进剂对原油具有较好的降凝，降黏效果，运行温度40℃以上时降黏幅度约20％；30℃和25℃的降黏幅度可达46．3A％和68．9％；全线降凝幅度为12－14℃。另外，BEM－5剂具有很好的分散性，对河沾线原油具有良好的改性效果。加剂后可降低管道的运行温度，增加运行的性，并取得了一定的经济效益。     

高含蜡原油降凝减阻方法

以青海原油为例,对高含蜡低胶质沥青质原油的降凝减阻方法进行了研究。研究表明：高含蜡低胶质沥青质原油,蜡晶多且大,在低温时能够形成可逆网状结构,热处理温度高,处理效果差,而且处理温度选择不当还会使原油的低温流动性恶化。采用降凝剂降凝减阻效果明显优于热处理。加剂处理原油的物性受加热历史和强剪切速率影响很大,多次重复低温加热或在析蜡高峰进行强剪切,会严重影响加剂原油的低温流动性。由于高合蜡低胶质原油组分的影响,降凝剂的降凝作用还不够理想,需要进一步研究。     

火灾对埋地管道中油品温度影响的数值研究

地面发生火灾时,土壤中原有的热平衡被破坏,土壤温度、地下管道温度将产生变化,从而进一步影响管内输送介质的温度,使其不断升高,当油品温度升高到一定值时,管道安全将受到影响.针对此情况建立非稳态传热模型,给出了微分方程;运用有限差分法对模型进行了数值模拟计算,其中对管道采取分段传热计算,并对结果进行分析.通过该研究,得出发生火灾后,埋地管道内输送油品的沿程温度变化规律,从而为火灾后的埋地输油管道性能安全评估提供了科学依据.     

稠油掺稀后混油黏度计算方法的研究

稀释输送是传统的稠油降黏输送方法,因其工艺简单,降黏效果在管输过程中较稳定,一直在国内外得到广泛应用。但稠油中加入稀油后其混油黏度又是一个难点,混油黏温数据是摩阻计算的重要参数,是输油管道设计和运行管理的重要参数,其准确性对水力计算结果至关重要。对混合原油的黏度计算,国内外学者提出了不少经验公式、半经验公式以及计算图表,且大多是利用实验数据通过线性回归得到的,每种模型都有一定的适用范围。通过对Cragoe模型进行修正,得出稠油掺入稀油黏度计算需分段选择模型的结论。     

原油顺序输送的现状与展望

通过对国内外现有油品顺序输送管道的发展情况的了解,以及对国内外油品顺序输送中的混油机理、界面检测、界面隔离、减少混油措施等现有技术进行总结,对国产原油-进口原油顺序输送所应解决的问题进行了阐述,最后提出对顺序输送技术的展望,并提出应该急需研究的油品顺序输送所应注意的相关技术问题。     

原油管道漏磁检测技术影响因素分析

根据漏磁检测原理制备了多种型号的管道漏磁内检测器,并将检测器在多条原油管道上进行了检测。综合分析各条管道的检测情况,可以确定除了检测器自身因素外,仍有管径、油品、运行方式和运行温度等因素对检测效果有一定的影响。通过对比不同管径、不同工艺参数下的检测结果,并对这几项因素的影响进行分析,初步确定了管径、油品、运行方式和运行温度等因素对检测效果的影响规律,并给出了一些降低其影响的措施。     

西部原油管道注入支线投产与运行分析

以西部原油管道三塘湖注入支线投产工程为例,运用实验方法,分析注入油品对干线运行产生的影响。认为在2~50℃的范围内,向兰成油中掺入小于等于40%的三塘湖原油,不会对西部原油管道的安全运行产生影响。通过进一步研究制定并实施管道投产及注入方案,确保注入支线及干线管道安全平稳运行。三塘湖注入支线投产为同类管道注入支线投产工作提供借鉴。     

基于FLUENT的曲西原油管道停输过程模拟

文中根据曲西含蜡原油管道基础数据及外输油品物性参数,运用FLUENT软件,基于数值模拟得出了曲西管道在停输后的温降过程。建立曲西原油管道及其外部土壤的物理和数学模型,并设置基本参数。观察原油温降过程,通过模拟停输后管道及其周围土壤温度场的分布,以及油品的自然对流。最后得出了管道停输后管内原油温度随时间的变化规律及管道的允许停输时间及最佳停输时间,结果对曲西管道健康运行有参考意义。     

稠油降黏集输方法综述

综述了几种常用降黏集输方法（包括加热降黏、乳化降黏、低黏液环输送和掺稀输送等）的降黏原理及优缺点,并介绍了各方法的发展情况及应用现状。针对稀释降黏法,利用液化石油气（LPG）替代部分重稀释剂的稠油降黏方法更经济有效。通过对几种降黏输送方法的综合比较,认为采用化学降黏方法在稠油降黏中具有一定的优势,最后指出研制多元复配型高效降黏剂,研制高效（既降凝又降黏）的降凝降黏剂及利用各种方法的复合技术进行降黏将是稠油降黏技术的主要发展方向。     

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.     

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.     

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.     

Seaport performance analysis using robust non-parametric efficiency estimators

Abstract

Seaport services have been developing year on year, playing an increasingly important role in the economy and the transportation markets of each country. This increases interest in measuring their performance. This paper evaluates the performance of a set of European seaports by means of robust non-parametric approaches. Using order-m and bootstrap procedures, the major problems of traditional data envelopment analysis and free disposal hull methods – concerning noise, presence of outliers and the ‘curse of dimensionality’ – are overcome. With this study considerable levels of inefficiency were found in the European seaports sector.     

Bicycle parking: a systematic review of scientific literature on parking behaviour,parking preferences,and their influence on cycling and travel behaviour

ABSTRACT

Cycling is experiencing a revival in many cities. Research has focused on the determinants of cycling – in particular the role of the built environment and road infrastructure. Bicycle parking has received little attention – even though bicycles are parked most of the time. This article reviews the scientific literature on bicycle parking and identifies existing gaps in research and knowledge. The review analyses 94 peer-reviewed papers identified through a search in Scopus and Web of Science, in December 2017. The annual number of papers increased 15-fold between 1995 and 2017. Overall, the level of evidence on the importance of bicycle parking is limited. The majority of studies are based on cross-sectional data with the presence of parking as a binary independent variable. Most studies focus on bicycle parking at public transport stops and at work places. Few studies report on bicycle parking throughout cities, and hardly any on parking at residential locations. Bicycle parking supply and quality appears to be a determinant of cycling for current and potential cyclists. Our findings can serve as input for an evidence-based debate on the role of bicycle parking. For practitioners, our research supports investment in bicycle parking, but acknowledges that a proper evaluation of such initiatives needs to be conducted to increase the level of evidence.     

Multilevel analysis of daily time use and time allocation to activity types accounting for complex covariance structures using correlated random effects

In this paper multilevel analysis is used to study individual choices of time allocation to maintenance, subsistence, leisure, and travel time exploiting the nested data hierarchy of households, persons, and occasions of measurement. The multilevel models in this paper examine the joint and multivariate correlation structure of four dependent variables in a cross-sectional and longitudinal way. In this way, observed and unobserved heterogeneity are estimated using random effects at the household, person, and temporal levels. In addition, random coefficients associated with explanatory variables are also estimated and correlated with these random effects. Using the wide spectrum of options offered by multilevel models to account for individual and group heterogeneity, complex interdependencies among individuals within their households, within themselves over time, and within themselves but across different indicators of behavior, are analyzed. Findings in this analysis include large variance contribution by each level considered, clear evidence of non-linear dynamic behavior in time-allocation, different trajectories of change in time allocation for each of the four dependent variables used, and lack of symmetry in change over time characterized by different trajectories in the longitudinal evolution of each dependent variable. In addition, the multivariate correlation structure among the four dependent variables is different at each of the three levels of analysis.     

从"神经末梢"到"国际枢纽"——十六大以来广西交通发展综述

文章总结了党的十六大以来广西交通发展取得的成绩,指出广西交通正在从"神经末梢"发展为"国际枢纽",为广西经济社会发展提供了重要支撑。     

Increasing urban tram system efficiency,with battery storage and electric vehicle charging

This paper examines the possible placement of Energy Storage Systems (ESS) on an urban tram system for the purpose of exploring potential increases in operating efficiency through the examination of different locations for battery energy storage. Further, the paper suggests the utilisation of Electric Vehicle (EV) batteries at existing Park and Ride (P&R) sites as a means of achieving additional energy storage at these locations. The study achieves this through MATLAB modelling utilising captured GPS data and publically available information. This study examines the scenario of uni-directional substations with no interconnection between the overhead catenary for both directions of travel, and discusses the trade-offs between ESS size and required current limits.The results show the savings in both energy and basic CO₂ emissions alongside the discussion of Return on Investment (RoI) that can be achieved through the potential installation of ESS at identified ideal locations along the tram network. Moreover, this may be extended to the use of EVs as stationary ESS sited at the existing P&R facilities. Further, the model may also be used to inform future infrastructure upgrades and potential improvements to air quality within urban environments.