石化装置腐蚀环境中有机非金属管材的应用

针对石化装置普遍应用的几种有机非金属管材,通过对其物理机械性能、耐腐蚀性能的对比,并结合兰州石化公司有机非金属管材应用实际情况,对有机非金属管材的使用范围及其局限性进行综合分析,最后重点讨论氯化聚氯乙烯非金属管道的性能特征,为石化生产装置合理选择非金属管道材料提供一定的参考.     

Immigration, residential location, car ownership, and commuting behavior: a multivariate latent class analysis from California

Using latent class cluster analysis, this paper investigates the spatial, social, demographic, and economic determinants of immigrants’ joint distribution among travel time, mode choice, and departure time for work using the 2000 Census long form data. Through a latent tree structure analysis, age, residential location, immigration stage, gender, personal income, and race are found to be the primary determinants in the workplace commute decision-making process. By defining several relatively homogeneous population segments, the likelihood of falling into each segment is found to differ across age groups and geography, with different indicators affecting each group differentially. This analysis complements past studies that used regression models to investigate socio-demographic indicators and their impact on travel behavior in two distinct ways: (a) analysis is done by considering travel time, mode choice, and departure time for work simultaneously, and (b) heterogeneity in behavior is accounted for using methods that identify different groups of behavior and then their determinants. Conclusively the method here is richer than many other methods used to study the ethnically diverse population of California and shows the addition of geographic location and latent segment identification to greatly improve our understanding of specific behaviors. It also provides evidence that immigrants are as diverse as the non-immigrant population and transportation policies need to be defined accordingly.

开口加劲肋正交异性钢桥面铺装力学分析

文章以开口加劲肋正交异性钢桥面铺装体系作为研究对象,建立了包括桥面板和铺装的整体三维有限元分析模型,研究了荷载作用下铺装层的力学特性。分析表明,横向拉应力是开口加劲肋正交异性钢桥面铺装设计的一个重要控制指标;开口加劲肋正交异性钢桥面铺装层间剪应力较大,在铺装结构设计时应注意选择具有较强抗剪强度的粘结材料;开口加劲肋正交异性钢桥面铺装对车辆荷载的应力应变响应具有很强的局部效应。     

成品油管道水击保护

长距离成品油管道在密闭输送过程中,出现非正常停泵、误关阀门及混油界面经过泵等均会引起水击现象发生。水击波沿管道传播,极易导致管道局部超压而造成管道破裂、损坏设备等,故水击保护成为成品油管道密闭输送关键性的工艺技术之一。金嘉湖成品油管道在全线水击保护控制方面采用了进出站压力调节系统、分输站分油流量调节系统、出站压力超高泄放系统、进站低压泄放保护系统、进出站压力超限停泵联锁保护系统来保证管道事故工况时的安全。     

改进振动法在地下工程动力时程计算中的应用

地下工程受到周围土体的约束作用,其动力反映与地面工程有所区别,如将源于地面工程的振动法用于地下工程的动力时程计算分析,需要进行相应的改进.文章通过计算分析发现,振动法用于地下工程动力时程计算时,在计算模型边界条件和波动传播时间效应方面不能反映波动对地下工程作用的实质;通过对比分析,在这两个方面对常规振动法进行了改进;提出了适用于地下工程动力时程计算的改进振动法.该方法的计算模型采用左右两侧粘弹性底部固定的人工边界条件,波动输入采用能够反映波动传播时间效应的分层加速度动态输入法,其计算分析结果与理论解吻合较好,适用于地下工程的动力时程计算分析.     

泡沫沥青冷再生施工技术节能减排效益分析

泡沫沥青冷再生施工作为一种路面废旧材料再生利用新型冷再生技术,其混合料除了具有良好的路用性能,施工中还可以起到明显的节能减排作用,是发展循环经济、创建环境友好节约型社会的重要举措,目前已开始得到应用和推广;通过对泡沫沥青冷再生施工技术节能效益分析,了解其节约资源、保护环境、减少污染、降低造价等优点。     

竹洲大桥主桥结构设计及受力分析

梁拱组合桥作为一种新的桥型,因造型美观、受力明确、施工工艺成熟等特点,在国内桥梁建设中得到了广泛应用和推广。文章以百色市竹洲大桥为例,阐述了该桥的结构设计要点,并采用Midas/Civil V2006与ANSYS软件建立几何模型,计算分析其主桥结构的受力情况,为梁拱组合桥的结构设计提供参考。     

某大桥地震作用下的时程响应分析

文章以某桥主桥2×100m的梁-斜拉组合体系为研究对象,采用ANSYS有限元软件对该桥进行了抗震性能研究,并基于地震时程分析法,评估了该大桥在地震荷载作用下的应力和位移响应情况,找到了该桥的薄弱环节,为该桥的设计提出有益的建议。     

来马路隧道超前地质预报典型不良地质体雷达数据解析

文章根据广西来宾至马山高速公路隧道超前地质预报成果,介绍了地质雷达数据采集、处理的要点,并结合探测实例分析了项目区常见的不良地质体(溶洞、断层带、裂隙密集带)的雷达反射波特征。     

Guidance for transport planning and policymaking in the face of an uncertain future

Uncertainty of outcome is widely recognised as a concern facing decision-makers and their advisors. In a number of spheres of policy, it appears uncertainty has intensified in the face of globalisation, economic instability, climate change, technological innovation and changing consumer preferences. How can planners and policymakers plan for an uncertain future? There is growing interest in, and use of, techniques that can help decision-making processes where deep uncertainty is involved. This paper is based upon one of the most recent international examples of a foresight exercise employed to examine uncertainty – specifically that which concerns uncertainty over the nature and extent of future demand for car travel. The principal focus of the paper is on the insights and guidance this examination of uncertainty brings forth for transport planning and policymaking. To accommodate deep uncertainty requires a flexible and open approach in terms of how policy and investment possibilities are formulated and judged. The paper argues for a focus upon the Triple Access System of spatial proximity, physical mobility and digital connectivity as a framework for policy and investment decisions that can harness flexibility and resilience. Uncertainty becomes an opportunity for decision-makers with the realisation that they are shaping the future rather than (only) responding to a predicted future. The paper outlines two forms of policymaking pathway: regime-compliant (in which adherence to trends and the nature of the world we have known pushes policy) and regime-testing (in which the nature of the world as we have known it is brought into question and vision pulls policy decisions). Stronger orientation towards regime-testing to assist in managing an uncertain future is advocated.