中、小口径管道法兰对口器

过去,法兰对口一直借助条形水平尺和钢角尺,这种方法操作起来比较繁琐,对口质量难以保证。研制的中、小口径管道法兰对口器,采用四连杆机构定心,两块定位板定位,利用丝杠调整连杆机构的径向位置,可完成Φ15 9mm～Φ2 19mm的直段钢管的法兰对口工作。     

成品油管道电动执行机构力矩故障分析及改进

执行机构在使用中会出现各种故障,其中力矩故障最频繁。文中通过对阀门不同部位摩擦力的变化及阀门限位的分析,找出了产生力矩故障的原因。针对不同的原因结合成品油管道的特点,采取力矩保护参数修改、限位调整、阀杆及填料润滑保养、阀门排渣润滑、定期加换油等措施,通过在成品油管道中的实践应用,取得了较好的效果。     

基于法兰联接系统松弛特性的多锥面法兰研究

文中针对现有普通法兰联接系统的应力松弛特性问题,设计了一种新型多锥面法兰,通过对法兰联接系统结构上的改进,去掉了原有法兰连接系统的垫片,明显减少了法兰连接系统的应力松弛,并通过法兰多锥面配合联接和法兰螺纹联接,增强了法兰联接的联接刚度,进一步减小了法兰连接系统的蠕变松弛,改进了法兰联接性能。实验测定和实际应用证明：该新型多锥面法兰可以有效减小法兰联接系统的应力松弛,防止法兰联接失效。     

温度波动对螺栓法兰连接系统垫片应力的影响

温度波动会造成螺栓法兰连接系统中垫片应力松弛,从而影响其密封性能。文章以DN80法兰接头为研究对象,通过ABAQUS软件建立了三维有限元模型,分析了温度波动对垫片应力的变化,研究了垫片与螺栓载荷变化的机理。结果表明,螺栓法兰连接系统在温度变化时存在着一定的温度滞后现象;当温度波动时,垫片应力随温度的降低而减小,随温度的升高而增大,波动结束后垫片表现出“内紧外松”的应力分布现象。在这一过程中,垫片的热膨胀与温度场的滞后性是垫片应力变化的主要因素。研究结果为螺栓法兰连接系统的进一步优化和改进提供了有力支持。     

管路附件局部摩阻对管输能力的影响

在成品油长输管道中,阀门、法兰等管道设备附件与管路内径不同使管路局部摩阻增大,从实际工作角度出发,具体研究了管件内径小于管道内径的情况下,管道输送介质流态对管输能力的影响,介绍了消除此类问题的的技术措施,提出了阀门、法兰等管件在设计选型期的建议以及此类管件安装施工中应注意的问题.     

石油化工装置管道系统的泄漏及预防

本文着重探讨了管道系统中管道、法兰密封面及阀门泄漏的原因、种类和主要泄漏部位。介绍了配管设计和施工安装过程中避免管道系统泄漏的一些主要措施。     

应用CAESAR Ⅱ软件对空冷器入口管线的优化设计

为提高大管径分馏塔顶空冷器入口管线的安全性,应用CAESAR Ⅱ软件,对其进行模型建立和数据分析。在正常操作工况及蒸汽吹扫工况下,通过调整空冷器入口管线的安装形式,对比一次应力、二次应力、管嘴受力、法兰泄漏的分析报告,可得出结论:可以通过增加管线长度、改变管道走向等方法对空冷器入口管线进行优化,增加其柔性,减少对空冷器管嘴的作用力,最终获得安全合理的安装方案。     

小口径管道马鞍口切口机设计

针对管道连接很多,而目前马鞍口加工的方法费时费力的问题,设计了一种适用于小口径管道马鞍口加工的设备。文中介绍了该设备的设计思路、结构以及工作原理,并通过实验验证了该设备具有加工管道马鞍口效率高,加工质量好等优点。     

低温环境下管道法兰连接的应力分析

文中在考虑温度作用的前提下,对低温管道中的法兰进行了不同螺栓强度等级和螺栓预紧力下的"拉伸+弯曲"组合工况的有限元分析。研究表明:法兰最大应力出现在螺栓上,螺栓的预紧力和强度等级的降低都将对法兰应力分布产生重要的影响。同时,文中也给出了法兰外侧的位移随螺栓预紧力和强度等级的变化规律。最后,通过现场测试验证了数值模拟的准确性。该研究结果可以为输油管线法兰连接的预紧力设定提供参考。     

化工管道支吊架设计

化工管道支吊架（简称管架）类型复杂多样,适用条件各不相同.化工管道本身的特点,决定了管架设计的高标准高要求,可查阅技术文献标准,但针对性不强,层次性、侧重点不同.因此,根据化工项目的管架设计经验,说明管架设计的合理时间,明确其对设计效率的重要性;针对使用频繁的滑动架、导向架,常见重要管道,详细阐述其管架设计常规;针对脱空管道,阐述其预防方法.在管架的选择和使用方面,对应力及非应力管道的管架设计具有一定的适用性和借鉴意义.     

Rethinking bus punctuality by integrating Automatic Vehicle Location data and passenger patterns

This paper investigates punctuality at bus stops. Although it is typically evaluated from the point of view of bus operators, it must also account for users, as required in recent service quality norms. Therefore, evaluating punctuality at bus stops is highly important, but may also be a complex task, because data on both bus arrivals (or departures) and users must be taken into account and processed. Data on buses can be collected by Automatic Vehicle Location (AVL) systems, but several challenges must be addressed in order to use them effectively. Passengers data at bus stops cannot be derived from AVL, but they can be used to derive passenger patterns and need to be integrated into processed AVL data. This paper proposes a new punctuality measure defined as the fraction of passengers who will be served within an acceptably short interval after they arrive. A method is proposed to determine this measure: it provides (i) several rules to handle AVL collected data, (ii) a procedure integrating processed AVL data and potential passengers’ patterns and (iii) a hierarchical process to perform the punctuality measure on each bus route direction of a transit network, as well as for every bus stop and time period. The paper illustrates the experimentation of this method on more than 4,000,000 data of a real bus operator and represents outcomes by easy-to-read control dashboards.     

Using non-real-time Automatic Vehicle Location data to improve bus services

Although real-time Automatic Vehicle Location (AVL) data is being utilised successfully in the UK, little notice has been given to the benefits of historical (non-real-time) AVL data. This paper illustrates how historical AVL data can be used to identify segments of a bus route which would benefit most from bus priority measures and to improve scheduling by highlighting locations at which the greatest deviation from schedule occurs. A new methodology which uses historical AVL data and on-bus passenger counts to calculate the passenger arrival rate at stops along a bus route has been used to estimate annual patronage and the speed of buses as they move between stops. Estimating the patronage at stops using AVL data is more cost-effective than conventional methods (such as surveys at stops which require much more manpower) but retains the benefits of accuracy and stop-specific estimates of annual patronage. The passenger arrival rate can then be used to calculate how long buses spend at stops. If the time buses spend at stops is removed from the total time it takes the bus to traverse a link, the remaining amount of time can be assumed to be the time the bus spends moving and hence the moving speed of the bus can be obtained. It was found that estimation of patronage and the speed of buses as they move between stops using AVL data produced results which were comparable with those obtained by other methods. However the main point to note is that this new method of estimating patronage has the potential to provide a larger and superior data set than is otherwise available, at very low cost.     

Mitigating negative impacts of near-side bus stops on cars

Bus stops are often placed short distances upstream of signalized intersections. Buses that dwell at one of these so-called near-side stops can impede queued cars upstream from discharging through the intersection during green times. Residual car queues can form at the intersection as a result. The smaller the distance between a stop and its intersection, the greater the problem can be.Models are formulated to address this problem using kinematic wave theory. The models can be used to determine where to place a near-side stop to achieve a target level of residual car queueing. In addition, the models are used herein to develop a scheme for mitigating residual car queues by briefly detaining some buses from reaching the stop. The scheme can be applied selectively, so that the times that detained buses depart from the stop are not postponed. The buses are therefore not delayed over the longer run. Analysis indicates that this bus-holding scheme can significantly reduce car delays and queueing. Our models for placing stops and holding buses are shown to be robust to systematic and random changes in car flow.     

Time of day intervals partition for bus schedule using GPS data

Time of day partition of bus operating hours is a prerequisite of bus schedule design. Reasonable partition plan is essential to improve the punctuality and level of service. In most mega cities, bus vehicles have been equipped with global positioning system (GPS) devices, which is convenient for transit agency to monitor bus operations. In this paper, a new algorithm is developed based on GPS data to partition bus operating hours into time of day intervals. Firstly, the impacts of passenger demand and network traffic state on bus operational performance are analyzed. Then bus dwell time at stops and inter-stop travel time, which can be attained based on GPS data, are selected as partition indexes. For buses clustered in the same time-of-day interval, threshold values of differences in dwell time at stops and inter-stop travel time are determined. The buses in the same time-of-day interval should have adjacent dispatching numbers, which is set as a constraint. Consequently, a partition algorithm with three steps is developed. Finally, a bus route in Suzhou China is taken as an example to validate the algorithm. Three partition schemes are given by setting different threshold values for the two partition indexes. The present scheme in practice is compared with the three proposed schemes. To balance the number of ToD intervals and partition precision, a Benefit Evaluation Index is proposed, for a better time-of-day interval plan.     

Sight distance analysis of highways using GIS tools

Analyzing the distance visible to a driver on the highway is important for traffic safety, especially in maneuvers such as emergency stops, when passing another vehicle or when vehicles cross at intersections. This analysis is necessary not only in the design phase of highways, but also when they are in service. For its use in this last phase, a procedure supported by a Geographic Information System (GIS) has been implemented that determines the highway distances visible to the driver. The use of a GIS allows the sight distance analysis to be integrated with other analyses related to traffic safety, such as crash and design consistency analyses. In this way, more complete analyses could be made and costs shared. Additionally, with the procedure proposed it is possible to use data regarding the trajectory of a vehicle obtained on a highway with a Global Positioning System (GPS) device. This application is very useful when highway design data are not available. The procedure developed and its application in a case study are presented in this article.     

工况信息数据采集系统在水平定向钻穿越施工中的应用

水平定向钻施工中的工况信息数据长期依赖人工记录,容易出现人为误差、漏记、补记现象,在定向钻工况变化或施工出现故障时,不能及时地综合分析工况参数变化的历史趋势。此系统可以对水平定向钻施工中的钻杆扭矩、钻进推力、回拖力、泥浆流量等工况参数进行实时采集、处理,通过工控组态软件Controx2000以直观的曲线、图表形式进行参数的趋势显示。试验证明：此系统能够对水平定向钻穿越施工中的参数进行实时采集、处理、显示、存储。施工过程中或工程结束后可对工况信息进行回放显示和分析,能够满足定向钻施工管理的实际要求。     

A dynamic station strategy to improve the performance of flex-route transit services

As an innovative combination of conventional fixed-route transit and demand responsive service, flex-route transit is currently the most popular type of flexible transit services. This paper proposes a dynamic station strategy to improve the performance of flex-route transit in operating environments with uncertain travel demand. In this strategy, accepted curb-to-curb stops are labeled as temporary stations, which can be utilized by rejected requests for their pick-up and drop-off. The user cost function is defined as the performance measure of transit systems. Analytical models and simulations are constructed to test the feasibility of implementing the dynamic station strategy in flex-route transit services. The study over a real-life flex-route service indicates that the proposed dynamic station strategy could reduce the user cost by up to 30% without any additional operating cost, when an unexpectedly high travel demand surpasses the designed service capacity of deviation services.     

Effect of signal coordination on traffic emission

This study investigates the effect of traffic signal coordination on emissions and compares it with their effects on operational performance measures of delay and stops. Various platoon ratios are obtained by simulating cycle lengths and offsets. Our results indicate that the impact of the cycle length on delay is more significant than those on stops and emissions for under-saturation traffic conditions. Given a fixed cycle length, increasing the platoon ratio can reduce delay, stops, and emissions, with reduction in emissions being correlated with stops than delay. The effect on emissions from the platoon arrival with respect to the onset of green or red indication is identified. With the same cycle length and platoon ratio, the early arrival situation, when the leading vehicles of a platoon encounters the red signal, can generate more emissions than are associated with late platoon arrival, when the last few vehicles in a platoon are stopped at the intersection by the onset of the red signal.     

Evaluate bus emissions generated near far-side and near-side stops and potential reductions by ITS: An empirical study

In this paper, we use second-by-second automatic vehicle location data to estimate bus emissions near far-side and near-side stops. We classify the bus running state near a stop into approach, dwell, and departure. A vehicle specific power approach is used to estimate bus emissions for each state. We show that bus emissions generated near stops can be significantly reduced by using certain intelligent transportation systems techniques.     

Not All Transfers Are Created Equal: Towards a Framework Relating Transfer Connectivity to Travel Behaviour

Abstract

Walking from origins to transit stops, transferring between transit lines and walking from transit stops to destinations—all add to the burden of transit travel, sometimes to a very large degree. Transfers in particular can be stressful and/or time‐consuming for travellers, discouraging transit use. As such, transit facilities that reduce the burdens of walking, waiting and transferring can substantially increase transit system efficacy and use. In this paper, we argue that transit planning research on transit stops and stations, and transit planning practice frequently lack a clear conceptual framework relating transit waits and transfers with what we know about travel behaviour. Therefore, we draw on the concepts of transfer penalties and value of time in the travel behaviour/economics literature to develop a framework that situates transfer penalties within the total travel generalized costs of a transit trip. For example, value of time is important in relating actual time of waiting and walking to the perceived time of travel. We also draw on research to classify factors most important to users’ perspectives and travel behaviour—transfer costs, time scheduling and five transfer facility attributes: (1) access, (2) connection and reliability, (3) information, (4) amenities, and (5) security and safety. Using this framework, we seek to explicitly relate improvements of transfer stops/stations with components of transfer penalties and changes in travel behaviour (through a reduction in transfer penalties). We conclude that the employment of such a framework can help practitioners better apply the most effective improvements to transit stops and transfer facilities.