裂解炉炉管吊耳弯头焊接裂纹产生原因分析

由于在更换文丘里管的施工中,吊耳弯头两端焊缝及母材不断产生裂纹,导致施工无法进行。通过研究吊耳弯头材质化学成分及焊缝的金相组织,找出产生焊接裂纹的原因。利用金相检验、化学成分分析、渗透检验等方法分别对母材及焊缝的开裂原因进行分析。结果表明：母材与焊缝附近开裂本质一致,都是源于热应力,在焊接状态下由于母材中碳和铜含量超标,造成母材脆性开裂。该批次吊耳弯头为不合格品,不能使用。     

Inconel600氯化反应器焊缝开裂失效分析

采用扫描电镜及电子探针、金相组织、化学成分、力学性能等分析方法,系统分析了Inconel600氯化反应器焊缝开裂原因。认为焊缝开裂的原因是焊缝柱状晶粗大,存在气孔、夹渣、缩松和夹杂缺陷,焊缝强度较低;反应介质脱水不彻底,在高温下形成氢离子腐蚀,形成1 mm的均匀腐蚀层,降低了焊缝的强度;铬的碳化物沿晶界析出,使晶界处贫铬,产生氯离子晶间腐蚀,使焊缝强度急剧降低,导致焊缝在设备运行时开裂。     

放空阀法兰焊缝断裂失效原因分析

针对某压气站压缩机下游放空阀法兰焊缝断裂的情况,采用外观检测、无损检测、化学分析、金相分析和有限元计算等方法,对该失效法兰进行了失效原因分析。结果表明:该焊缝断裂属于多源断裂,焊缝上部放空装置较重,在较大风力的作用下,在立管焊缝附近产生很大弯曲载荷,内焊趾处产生应力集中,最终导致裂纹扩展并发生断裂。结合现场施工和设计情况,提出了防止发生类似事故的建议。     

在役压力容器管座角焊缝的相控阵超声检测

为了提高在役压力容器管座角焊缝缺陷的检测效率以及缺陷检测的可靠性,文中对在役压力容器管座角焊缝相控阵超声检测方案进行验证。调整了用于在役压力容器管座角焊缝检测的扫查装置,确定了实验方案中实际缺陷长度的计算方法。通过相控阵超声检测扫描获得的图谱,可以对管座角焊缝的典型缺陷进行识别和评定。该研究同时可协助解决管座角焊缝不同类型缺陷的定性分析和定位难题,对管座角焊缝相控阵超声检测图像识别和结果评定有借鉴作用。     

城镇埋地燃气管道失效原因分析

文中对发生泄漏的某城镇燃气管道进行了失效原因分析,通过尺寸测量、宏观分析、电镜分析、化学成分及拉伸性能分析、金相分析等,得出了燃气管道断裂原因为管道环焊缝在外部载荷的应力作用下发生了断裂扩展,并确定了管道起源开裂的位置。     

基于无损检测的输油管道环焊缝缺陷安全评估

输油管道环焊缝开裂可能造成严重的威胁,但漏磁内检测技术难以精确识别及量化环焊缝缺陷。因此,基于漏磁内检测数据结果的适用性评价结果可能存在较大的偏差。为此,对比环焊缝缺陷无损检测结果,分析漏磁内检测环焊缝缺陷的尺寸量化精度,并基于无损检测的缺陷尺寸进行失效评估,结合管道实际运行压力,进行疲劳强度校核。评估结果显示无损检测识别的环焊缝缺陷均满足安全评定要求,不需要修复。     

衬砌开裂隧道的稳定性分析及治理技术

隧道衬砌开裂将影响隧道的承载能力和使用安全.文章主要分析了铁路隧道开裂状况及原因,对裂缝宽度的影响程度进行了分级,利用断裂力学的方法研究了衬砌开裂隧道的稳定性,并提出了相应的裂缝治理技术.     

北流-宝圩二级公路圆管涵加固设计与施工

文章结合工程实例,分析了圆管涵产生开裂病害的原因,通过验算确定针对性的加固方案,在实际施工中取得良好的效果.     

基于CAESAR Ⅱ的膨胀节开裂分析与解决方案

文中针对某化工厂管道试压时膨胀节被拉伸开裂的现象,采用CAESAR Ⅱ应力分析软件进行建模计算,分析了膨胀节开裂失效的原因,从调整支架和膨胀节选型两方面给出解决方案。结果表明,膨胀节内压推力可以通过支架约束也可通过带约束的膨胀节约束。     

顺层偏压隧道灾害处理及施工技术

形成隧道偏压的原因主要有:地形引起的偏压、地质构造引起的偏压、施工原因引起的偏压等.其中地质构造引起的偏压问题最为复杂.对于由地质构造引起的偏压荷载目前尚无成熟的计算方法,基本上是依靠经验和在工程实践中不断调整加以确定,缺乏系统的理论分析方法.文章结合国家重点工程渝怀铁路渔塘湾隧道穿越顺层岩体的工程实际,分析了造成该隧道衬砌、支护开裂变形的原因,对隧道在此类地质构造偏压条件下的开挖方法、支护形式、衬砌结构进行了简单介绍.该施工技术不仪使隧道按时按质完成,而且施工进展顺利,现场应用效果良好,具有一定的借鉴意义.     

Analysis of factors affecting the choice of route of pedestrians

Pedestrians as compared to vehicular traffic enjoy a high degree freedom of movement even in heavily congested areas. Consequently, there are more alternative links available to pedestrians between a given origin‐destination (O‐D) pair. This paper describes a study done by the University of Calgary to evaluate the factors affecting the choice of route on intra‐CBD trips or trips within the Central Business District (CBD).

An origin destination survey conducted in downtown Calgary, Alberta enabled the identification of the most significant factors influencing the choice. These factors were analyzed in relation to the physical characteristics of the location, personal characteristics of the trip maker and the type of the trip.

It appears that most people chose the shortest link and factors such as the level of congestion, safety or visual attractions were only secondary. This suggests that the length should be made a major consideration when planning and designing pedestrian links.     

Non-parametric analyses of efficiency of airports

This paper estimates the efficiencies and productivity changes of 12 international airports in the Asia-Pacific region based on data from 1998 to 2006. We apply stochastic frontier analysis (SFA) to compute efficiency estimates and use the Malmquist productivity index (MPI) to analyze productivity changes. We use the SFA model with a translog-type production function after testing the statistical hypotheses. According to the results of the SFA hypothesis tests, airports have experienced a technological regression; the deviations from the efficiency frontier are caused more by technical inefficiency than random noise. However, the inefficiency was found to decrease. The MPI reveals a declining trend resulting more from technological change than from efficiency change, with a decrease in inefficiency. Taken together, both the hypothesis tests and the MPI not only provide consistent conclusions, but also suggest that airports should concentrate on technological progress.     

波纹管应力分析研究进展

评述了波纹管应力理论研究方法的进展情况，围绕解析法、工程近似法和数值法，对波纹管理论研究中的一些主要成果作了较详细的回顾和总结，对各种研究方法作出了评价，展望了亟待解决的一些问题。     

注汽管道承压能力评估和实物试验验证

基于失效评估图技术对某注汽管道进行了承压能力评价,给出了管线在不同腐蚀壁厚情况下的极限承压能力和极限裂纹尺寸。并利用实物爆破试验验证了评价方法的安全性和有效性,通过对爆破断口进行宏观和微观分析,发现管段的开裂属于脆性开裂。     

实现多组态计量软件集中监控的可行性分析

天然气自动计量系统有多种组态软件,由于软件的不相通性,造成了计量系统数据采集的通用性差、数据传输与入库的时效性差、数据利用的可靠性低.结合各组态软件的实际情况,从设计上充分利用Oracle大数据处理能力以及Partition(分区表)的特性,实现历史数据的存储,应用WebService与COM+数据访问组件提供多层数据访问架构,采用OPC与DDE工业数据交换协议,实现了各站场计量数据的实时上传,为连续数据采集和实时监控提供了可能,节约了改造成本.     

城市轨道交通杂散电流监测系统概述

介绍了城市轨道交通工程中杂散电流不同的监测系统的构成,分析了集中式、分散式和智能型等监测系统的配置和功能,以及智能型实时在线监测系统的重要意义,为轨道交通工程杂散电流监测系统的选择与应用提供参考。     

埋地管道防腐保温层失效评价

明确埋地管道防腐保温层的技术评价标准,对埋地钢质管道的安全运行,延长管道使用寿命具有重要意义。为了对埋地管道防腐保温层做出有效评价,从间接检测与开挖检测2个方面,结合现场检测数据,提出了基于防腐保温层的电流衰减率、绝缘电阻率、质量状况与厚度的分级评价标准及基于4种评价指标的综合评判方法。工程实践表明,该评价标准对防腐保温层是否存在失效能做出有效判断。     

Preliminary results of an analysis of areas of influence in Shanghai

The main deficiency of most current modeling approaches to transportation can be identified as neglect of the integration of existing geographical knowledge in regard to the ex ante transport/land use modeling approaches, with its focus on territorial dynamics and theory development. This paper addresses this aspect of the problem by introducing a theoretical and methodological framework for the analysis of the interrelationship between land uses. The analysis attempts to determine to what extent the functional land use in a city can be considered an ordered pattern. The order sought does not rely on purely spatial configurations, but on the correlation of transportation and land use. The first section of this paper focuses on theoretical considerations. It stresses the fact that conventional approaches do not apply in the present context. It then suggests an alternative based on areas of influence and measured in terms of level of attractance of land uses. The second describes a procedure based on this alternative following the remarkable contribution of Hanjoul, Beguin and Thill. An application of this procedure to the analysis of Shanghai is then examined. Finally, an evaluation of the strategies for optimizing the interrelationship between land uses is presented. The paper concludes with a possible research agenda.     

输油管道中原油乳状液的流变性研究

原油乳状液的流变性是原油开采后在管道中输送的重要研究方面,为了更好地研究这一性质,采用电动搅拌机、偏光显微镜以及流变仪等仪器来测定不同含水率的原油乳状液在不同条件下的黏度,观测不同含水率的原油乳状液在偏光显微镜下的形态。并且分别对原油乳状液的黏度与含水率之间的关系以及与剪切速率之间的关系进行研究,初步确定了所测区块原油乳状液的转相点以及该区块原油乳状液的流变特性,为生产中的油气集输提供了理论依据。     

Direct analysis of the perceived importance of attributes of reliability of travel modes in urban travel

Reliability of travel modes was found to be the most important characteristic of transportation systems in several attitudinal investigations of individual travel behavior. This paper represents the first part of a research effort aimed at gaining a better understanding of the characteristics of reliability of transportation modes in urban travel. In this research, reliability characteristics are identified; their importance relative to each other is assessed, and an insight into possible structure of an objective reliability index is discussed. The research is based on perceived values of reliability, which were identified through a large attitudinal survey conducted in the Chicago metropolitan area.