城市天然气高压环网储气能力研究

研究了城市配气系统中的高压外环,介绍了城市高压外环天然气管道储气能力的计算方法,抽象出了城市高压外环天然气管道的物理模型,用适用于城市高、中压天然气管道的通用公式推导出高压外环管道储气能力的计算公式,最后进行了实例计算。     

高压燃气管道储气能力分析

高压燃气管道储气能力与两端压力和管长有着密切的联系.为了得到高压管道的储气量与压力和管长的关系,利用稳态仿真模型,采用四阶龙格-库塔法对模型进行求解,对求出的沿线压力进行线性拟合,得到沿线压力变化公式.结合储气定义推导出储气量与管长的关系式,并得到实例验证.从关系式来看,当管长等于最优管长时储气量最大.     

管道仿真技术发展与应用进展

文中从泄漏分析与检测、在线仿真、运行优化与储气调峰方面,分析了国内外管道仿真技术的应用现状。结合当前存在的主要问题,提出应针对仿真软件易用性、高度集成的建模技术和决策支持系统等开展深入研究,以加强对管道的控制及提高管道安全性。     

长输管线末段储气系统的研究

主要研究长输管线末段管道储存天然气系统。介绍了长输管线末段管道储存天然气的两种方法，阐明了长输管线末段管道的工况特点，给出了末段管道在输气的情况下储气能力的计算方法及应用条件，设计了长输管线末段管道储存天然气与原有相结合的计算程序。根据长输管线的供气方式采用末段管道储存天然气更加经济合理，对工程施工具有现实意义。     

燃气输配管网调峰过程的动态模拟分析

介绍了燃气输配管网储存天然气的方法.利用末段管道和储气罐的储气技术,采用动态模拟计算方法可以调整和优化设计,解决系统供需矛盾,向用户安全、稳定供气.输配管网的动态分析可以对燃气输配管网进行实时的仿真模拟,对管网中管网结构、管径、储气方式及其组合进行有效的调整,使管网运行参数最优.动态模拟方法是基于流体力学原理,用数学分...     

城市天然气管道的腐蚀风险与检测

通过对城市天然气管道所面临的腐蚀风险的阐述,并结合国内外油气管道事故的危害,对管道腐蚀检测的必要性进行了说明.文中提出了腐蚀内检测作为管道信息采集的一种方式,将为完整性管理提供科学有效的数据,并为管道的维修维护提供依据,为管道的安全有效运行提供保障.从工程应用的角度,结合实际工作经验,对城市燃气腐蚀内检测过程中的难点进行了分析,同时提出了解决方法,对腐蚀检测技术服务具有现实的指导意义.     

苏丹MELUT盆地原油外输管线B1标段智能通球

通过苏丹3/7区块原油外输管道B1标段智能通球施工实践过程,研究了原油长输管道投产前大口径长距离管道清管压缩空气供应问题,研究了使用压缩空气推动对速度有严格要求的管道智能检测器进行管道内几何检测的球速控制问题,介绍了依靠管道储气包和空压机组联合供气的气源解决方案和通过控制进气量、调节截断阀室开度、管道内加水组成PIG列车和智能球跟踪等多种措施,综合控制稳定球速,找到了大口径长距离管道使用压缩空气作为动力进行管道智能检测的可行的解决方法.     

基于SCADA系统的燃气管道泄漏监测系统模型设计

单一的燃气管道泄漏检测系统不经济,SCADA系统不仅能为泄漏检测提供数据源,而且能监控管道运行状况.因此,将检测系统集成到SCADA系统中,不但能充分利用SCADA系统的功能,而且也是管道自动化发展方向.介绍了城市燃气管道现有的监测技术和发展方向、输气管道检漏方法、管道泄漏监测技术的研究方法;设计了城市燃气管道温度、压力、流量的数据采集方案、原理、模型和采集的程序流程;给出了在VB中使用MSComm控件进行串口通信以及实现PC机对下位机的数据采集的方法;给出了用VB进行油气管道数据采集的编程步骤和部分界面.     

SPS在输油管道压力自动控制系统的应用

为研究输油管道压力自动控制系统中两种调节方式（节流调节、变速调节）的应用效果,结合肯尼亚1号线成品油管道,选用SPS软件,分别对出站控制阀节流调节和离心泵转速调节进行了模拟.得出结论：该管道在设计输量下,采用转速作为调节方式较节流调节更经济.通过对比两种调节方式下泵输出参数,分析出调速节能的原理在于提高了泵机组的能量利用率,使电机输出功率与泵扬程满足工况的要求即可,出站控制阈全开,避免了节流损失.     

数字辐射流动可视化系统设计与实现

介绍了一种利用数字辐射成像技术来实现高压不透明输送管道中高固多相黏稠物料流动成像的^60Co数字辐射流动可视化系统。首先阐述了该数字辐射流动可视化系统的总体构成,包括系统的基本原理和研制概况,进而介绍了该可视化系统的性能指标以及功能特点。该^60Co数字辐射流动可视化系统以扫描方式工作,能直接获得数字图像,可用于高压不透明输送管道中密相固液多相流流动机理的研究,其应用对推动高固多相黏稠物料管道输送及处置技术的发展具有重要意义。     

Greenhouse gas reduction potential of advanced traffic control

Reducing greenhouse gas (GHG) emissions from transportation in the context of the climate change issue and the associated Kyoto Agreement of 1997 is a challenge. Since urban transportation is a major contributor to greenhouse gases, measures are required to reduce these emissions. Given that during peak periods, road vehicles propelled by petroleum fuel‐based internal combustion engines produce a high level of GHG emissions due to stop and go operations, measures to improve traffic flow can play an effective mitigation role. This paper describes a simulation‐based methodology and a case study for the quantification of GHG emission reduction owing to advanced traffic control systems.     

金属波纹管膨胀节在燃气管网中的应用与事故预防

金属波纹管膨胀节是城市燃气管网的重要组成构件,它的安全稳定是城市燃气安全运行的重要条件.文中对金属波纹管膨胀节在燃气管网运行中的应用进行了介绍,对膨胀节事故进行了统计与失效原因分析,并开展了相关的试验研究.针对失效原因,对在管网建设中如何选用、安装膨胀节以及随后的运行过程中如何维护管理提出了建议.     

Using repeated cross-sectional travel surveys to enhance forecasting robustness: Accounting for changing mode preferences

Transportation system capacity and performance, urban form and socio-demographics define the influences and constraints conditioning the preferences of urban residents for different transport modes. Changes in characteristics of urban areas are likely to lead to changes in preferences for alternative modes of transport over time; as a consequence, statistical models to forecast mode choice need to be sensitive to both purposeful changes to urban systems as well as exogenous shocks. We make use of the 1996, 2001 and 2006 household surveys conducted in the Greater Toronto and Hamilton Area to study mode preference evolution and model forecasting performance. These repeated cross-sectional household surveys provide an opportunity to investigate aggregate structural changes in commuting mode preferences over time, in a manner sensitive to changes in the urban area. We focus on commuting mode choices because these trips are prime determinants of peak period congestion and peak spreading. We then address how to combine the three cross-sections econometrically in a robust way that allows for use of a single mode choice model across the entire period. Using independent data from 2012, we are able to compare the individual year and combined models in terms of forecasting performance to demonstrate the combined model’s more robust forecasting performance into the future.     

城市高压燃气管网动态模拟计算

采用偏微分方程特征线的数值分析及解非线性方程牛顿迭代法，对燃气高压管网不稳定流动问题从理论上进行了求解，并用Visual C＋＋编制了用户负荷随时间变化时高压管网压力分布的动态模拟程序。     

Low-carbon futures for Shenzhen’s urban passenger transport: A human-based approach

Shenzhen, one of China’s leading cities, has the potential to be a model for achieving China’s ambitious CO₂ emission reduction targets. Using data from a travel diary survey in Shenzhen in 2014, we develop a human-based agent model to conduct a scenario study of future urban passenger transport energy consumption and CO₂ emissions from 2014 to 2050. Responses to different policy interventions at the individual level are taken into account. We find that with current policies, the carbon emissions of the urban passenger transport sector in Shenzhen will continuously increase without a peak before 2050. Strengthening 21 transport policies will help Shenzhen to peak the carbon emissions by 2030 for passenger transport. Among these policies, the car quota policy and the fuel economy standard are essential for achieving a carbon peak by 2030. In addition, a package of seven policies, including fewer car quotas, a stricter fuel economy standard, raising parking fees, limiting parking supply, increasing EV charging facilities and subway lines, and improving public transport services, is sufficient to peak carbon emissions by 2030, although at an emissions level higher than for the 21 policies.     

Exhaust emissions and fuel consumption of a triple-fuel spark-ignition engine powered passenger car

This paper examines the influence of compressed natural gas, liquefied petroleum gas and gasoline fuel on the exhaust emissions and the fuel consumption of a spark-ignition engine powered passenger car. The vehicle was driven according to the urban driving cycle and extra urban driving cycle speed profiles with the warmed-up engine. Cause and effect based analysis reveals potential for using different fuels to reduce vehicle emission and deficiencies associated with particular fuels. The highest tank to wheel efficiency and the lowest CO₂ emission are observed with the natural gas fuelled vehicle, that also featured the highest total hydrocarbon emissions and high NO_x emissions because of fast three way catalytic converter aging due the use of the compressed natural gas. Retrofitted liquefied petroleum gas fuel supply systems feature the greatest air-fuel ratio variations that result in the lowest TtW efficiency and in the highest NO_x emissions of the liquefied gas fuelled vehicle.     

A ‘sustainability window’ of urban form

With global environmental change and the rise of global megacities, environmental and social externalities of urban systems, and especially of urban form, become increasingly prevalent. The question of optimal urban form has been debated and investigated by different disciplines in numerous contexts, including those of transport costs, land consumption and congestion. Here we elucidate theoretically how urban form and the urban transport system systematically modifies sustainability concerns, such as greenhouse gas emissions, local air pollution and congestion. We illustrate our analytical considerations with empirical analysis. Denser urban form would almost unambiguously mitigate climate change, but it would also lead to undesired effects, such as a higher proportion of urban dwellers affected by air pollution. Our study presents a ‘sustainability window’ by highlighting trade-offs between these sustainability concerns as a function of urban form. Only a combination of transportation policies, infrastructure investments and progressive public finance enables the development of cities that perform well in several sustainability dimensions. We estimate that a residential population density between 50 and 150 persons/ha and a modal share of environmental modes above at least 50% corresponds to the sustainability window of urban form. The parameters of the sustainability window of urban form is subject to policy changes and technological progress.     

Estimating time dependent O‐D trip tables during peak periods

Intelligent transportation systems (ITS) have been used to alleviate congestion problems arising due to demand during peak periods. The success of ITS strategies relies heavily on two factors: 1) the ability to accurately estimate the temporal and spatial distribution of travel demand on the transportation network during peak periods, and, 2) providing real‐time route guidance to users. This paper addresses the first factor. A model to estimate time dependent origin‐destination (O‐D) trip tables in urban areas during peak periods is proposed. The daily peak travel period is divided into several time slices to facilitate simulation and modeling. In urban areas, a majority of the trips during peak periods are work trips. For illustration purposes, only peak period work trips are considered in this paper. The proposed methodology is based on the arrival pattern of trips at a traffic analysis zone (TAZ) and the distribution of their travel times. The travel time matrix for the peak period, the O‐D trip table for the peak period, and the number of trips expected to arrive at each TAZ at different work start times are inputs to the model. The model outputs are O‐D trip tables for each time slice in the peak period. 1995 data for the Las Vegas metropolitan area are considered for testing and validating the model, and its application. The model is reasonably robust, but some lack of precision was observed. This is due to two possible reasons: 1) rounding‐off, and, 2) low ratio of total number of trips to total number of O‐D pair combinations. Hence, an attempt is made to study the effect of increasing this ratio on error estimates. The ratio is increased by multiplying each O‐D pair trip element with a scaling factor. Better estimates were obtained. Computational issues involved with the simulation and modeling process are discussed.     

Social and spatial effects of transforming the private vehicle fleet in Brisbane,Australia

Transformation of the motor vehicle fleet has been an important feature of the world’s peak car phenomenon. Very few urban transport studies have explored such important changes in large urban cities. Using an innovative green vehicle datasets constructed for 2009 and 2014, this paper investigates the ongoing change in urban private vehicle fleet efficiency (VFE) in Brisbane. The spatial patterns of VFE change were examined with social-spatial characteristics of the urban area. The results showed that the social and spatial effect of VFE changes remain uneven over urban space. The inner urban areas have experienced higher level of VFE change, whilst people in the outer and oil vulnerable areas showed a low tendency in shifting to more efficient vehicles. The implication of VFE change for future household vehicle adoption was also evaluated based on a cost-benefit analysis of new vehicle technology costs and expected fuel savings for households that choose a fuel efficient vehicle. The results show that imposing a stronger national fuel economy target in the long term would accelerate evolution of vehicle fleets and oil vulnerability reduction in Brisbane.     

Urban real-world driving traffic emissions during interruption and congestion

On-road emissions from urban traffic during interrupted and congested flow conditions are too high as compared to free-flow condition and often influenced by accelerating and decelerating speed due to frequent stop-and-go. In this study, we measured emissions from passenger cars and auto-rickshaws during peak and off-peak hours and analyzed according to different mileages with the instantaneous speed and acceleration for interrupted and congested traffic conditions. It was found that during flow, several short-events lasting over fractions of a second each lead to a sharp increase in pollutant emissions, indicating episodic conditions. The emission levels are sensitive to frequency and intensity of acceleration and deceleration, in accordance with the traffic-flow patterns and speed, besides mileages. Further, congestion conditions occur during both peak and off-peak hours, but last for different durations. The results are important in the sense that instantaneous estimates of pollutant emissions are necessary for the assessment of air quality in urban centers and for an effective traffic management plan.