Effect of interference fits on the fatigue lives of bolted composite joints

The effect of interference fits on the fatigue lives of bolted composite joints is investigated by conducting mechanical tests. Static and fatigue tests are carried out on specimens made of carbon-bismaleimide composites joined together as double-lap single-bolt joints. The bolts having interference fits ranging of 0 (neat fit), 0.5%, 0.75% and 1% are performed. The results demonstrate the relationship between fatigue life and different values of interference fits. After the fatigue tests, non-destructive evaluation (NDE) and scanning electron microscope (SEM) are used to observe the damage of the surrender and surface of the hole. The test results show that the interference fitted specimens have improved fatigue life compared to the neat fitted specimen. The NDE and SEM results reveal that the damage degree of interference fitted specimen is weaker than that for the neat fitted one.     

A socioeconomic analysis of commuting professionals

Transportation - Everyday commuting as a mobility phenomenon is well-investigated and has been the topic of many contributions. Nevertheless, the distinct determinants of the commuting...     

To kill a real option – Incomplete contracts,real options and PPP

This paper is concerned with the implications of public–private partnership agreements for the execution of expansion options in road infrastructure. More specifically, it analyzes the expansion of an existing two-lane road in Sweden, and examines the real options created by an intermediate type of road with three lanes. Interpreting the results from real option analysis in the light of incomplete contract theory, this paper finds that external congestion costs might necessitate public ownership to ensure a social optimal outcome in public–private partnerships.     

基于准平面假定的外贴CFRP板加固宽缺口混凝土梁刚度研究

宽缺口混凝土梁是为研究CFRP板与混凝土界面特性而构造一种新型混凝土梁.为分析该新型梁的变形与刚度特性,对11根外贴CFRP板加固的各类混凝土梁进行静载试验,并对其变形刚度进行详细的测试和研究.基于FRP类材料加固混凝土梁应变协调的准平面假定并考量CFRP板的刚度贡献,对加固后宽缺口混凝土梁的刚度计算公式进行理论推导,并将理论公式计算结果与实测结果进行比对.研究结果表明:外贴CFRP混凝土梁的刚度有小幅度提高,CFRP板能延缓裂缝的发展,减小梁的变形.     

某型汽轮机超速脱扣试验浅析

某型汽轮机的超速保护装置采用脱扣结构,文章针对该汽轮机的超速脱扣结构进行分析,总结此种超速脱扣装置的装配要求和试验方法,以利于该型汽轮机的生产。     

某船右主机不能正常建立滑油压力的故障排除

文章对某船右主机启动过程中,机带滑油泵不能正常建立滑油压力进行了分析,制定了针对性的排除故障措施,通过在机带滑油泵通舱管吸入口处安装吸入止回阀解决了滑油压力非正常下降的故障,实船应用证明措施合理,对同类故障排除有较好的借鉴意义。     

大跨度钢箱梁斜拉桥中跨合龙关键技术

以4座主跨超过400 m的钢箱梁斜拉桥中跨合龙控制为背景,对大跨度钢箱梁斜拉桥中跨合龙的2种方法进行对比分析,对合龙各主要工序的关键技术进行研究。提出了合龙段配切长度的计算公式和合龙口宽度连续观测的测点布置方式。建议:在调整好合龙口姿态后可不加压重,也可不采用临时劲性骨架锁定;采用无线采集设备采集合龙口结构的温度场,用激光测距仪测量合龙口宽度以提高观测效率和安全性;在悬臂施工阶段关注梁长累计误差并通过调整后续梁段的制造长度消除之。     

地铁车辆IGBT瞬态结温计算方法研究

基于IGBT模块封装的物理结构,分析了热量冲击导致芯片失效的主要原理.根据芯片热损耗的主要传递路径,建立了热量传递各环节的瞬态传热模型,并分别给出了瞬态温升计算方法.尤其对热量传递模型较复杂的走行风冷热管式散热器进行了详细分析和试验研究,并给出了获取散热器热阻抗模型实时参数的有效解决方法;最后,对芯片瞬态结温计算方法进行了总结,并开发了软件工具.文章介绍的计算方法和软件工具可推广应用,为IGBT模块瞬态结温计算提供重要参考.     

The Teachable Moments on Marine Mammal Tours: Watching versus Swim-With Tours

With the continuing growth of the tourism industry over recent decades, has come a change in tourist behavior from the traditional stereotypical 3-S tourist (sun, sand, sex) to an increasingly sophisticated and demanding tourist. These “new” tourists like to learn about history, nature, and wildlife, and they expect an educational component on wildlife tours. This study investigated swim-with-dolphin tours in Kaikoura, New Zealand with regard to the educational content and the overall anatomy of these tours, using data from observations on a total of 32 tours during December 2011. The resulting data were then compared with the data from Hrycik and Forestell's study, which investigated the content of questions asked by passengers on whale-watching tours in Stellwagen Bank National Marine Sanctuary. Results of the on-tour observations indicate that the surveyed tours display a structured approach to interpretation, which is customized to the specific tour anatomy of a “swim-with” tour, and varies in some parts significantly from “watch-only” tour interpretation.