Numerical analysis of crack under compression by 3D displacement discontinuity method

A 3D displacement discontinuity method is applied to solve the fracture mechanics problems of the mixed mode crack under compression. Friction between the surface of the closed crack is considered by establishing a simple and efficient iterative algorithm based on method of contact resistance mitigation. On the surfaces of the closed crack, the Mohr-coulomb rule is satisfied by iteration when the crack is in condition of sliding. The stress intensity factors are obtained using displacement fitting method. It is shown that the numerical results agree with the experimental results well and that friction plays an important role in resisting crack propagation.     

Experimental study on the liquid slug of cryogenic slug flow in inclined tubes

An experimental study was carried out to understand the phenomena of the boiling flow of liquid nitrogen in inclined tubes with closed bottom by using a high speed motion analyzer.The experimental tubes are 0.018 and 0.014 m inner diameter(ID) and 1.0 m in length.The range of the inclination angle is 45°-90° from the horizontal.The experimental observation on the liquid slug was carried out along the tubes.Statistical method was employed to analyze the experimental data.The experiment analyzed the influences of the inclination angle and the tube diameter on the liquid slug length and velocity.The results show the liquid slug propagation velocity increases with the decrease of inclination angle θ.For all cases,the maximum values of the mean liquid slug lengths were obtained at θ = 60°.The mean liquid slug lengths were greater for large tube at higher tube position.These conclusions provide a basis for further study liquid slug of cryogenic two-phase undeveloped slug flow.     

“Turn on the radio,bust out a song”: the experience of driving to work

Though driving to and from work has become a prevalent experience in the lives of individuals in every metropolitan region in the US, much remains to be learned about the activity from the perspective of the drivers. To increase our understanding of the motivation for certain travel behaviors, we must first know something about what those drivers experience. The existing literature explains much, but the application of new methodologies could improve our ability to explain the willingness of individuals to choose to drive through increasingly congested road networks. The results of this study of oral histories of 12 women commuters underscore the idea that commute should be seen as a set of subjective behaviors that contradict some existing assumptions about why individuals commute.     

Threshold controlled scheme of difference expansion techniques for reversible watermarking

Since Tian Jun proposed the difference expansion embedding technique, based on which, many reversible watermarking techniques were proposed. However, these methods do not perform well when the payload is high. In this paper, we proposed an expandable difference threshold controlled scheme for these three methods. Experiments show that our scheme improves the performance of these three methods for heavy payload.     

IQ非正交引起的载波和伪码跟踪误差分析

分析了直接下变频导航接收机中，I、Q信号的非正交引起的载波及伪码的跟踪误差。用码环及载波环的鉴别函数的零点来确定最终的跟踪误差表达式，并结合具体的实验测试结果进行了工程近似，分析结果显示载波及伪码跟踪误差与I,Q的相位差、时延差近似成线性关系，故在进行系统结构设计时，可根据系统的精度要求确定是否选择直接下变频的接收机结构。     

水泥稳定碎石基层质量控制要点及措施

结合沪宁高速公路扩建及泰州市沿江高等级公路水泥稳定碎石基层施工实践,从原材料质量、混合料质量、碾压工艺、施工延迟时间等方面入手,提出了水泥稳定碎石施工质量控制要点及保证措施。     

控制加荷速率减少地基沉降的研究

以京珠高速公路衡阳试验段的现场测试资料以及某机场的现场测试资料为依据，提出了加荷速率和沉降速率的具体控制数值，希望能对广大工程建设者有所帮助。     

我国汽车产业可持续发展面临的主要问题及对策研究

随着我国汽车保有量的迅速攀升,安全事故频发、环境污染严重、石油能源短缺和自主创新能力薄弱等负面问题日益突出,严重制约了汽车产业的健康持续发展。文章从安全、环保、节能和自主创新4个方面分析探讨我国汽车产业可持续发展所面临的主要问题,并提出相关措施和对策建议。     

二道垭隧道塌方原因分析与处理技术

处在断裂构造带附近的长大隧道洞室在开挖施工过程中,围岩出露往往复杂多变,因此,复杂的地质条件特别是软弱围岩常给长大隧道施工带来重重困难。文章结合二道垭隧道在软弱围岩施工过程中的塌方事故,分析了导致塌方的具体原因,并提出了相应的施工处理方案和相关建议。     

Why are work travel plans effective? Comparing conclusions from narrative and meta-analytical research synthesis

Reliable research synthesis is of high significance for a transport policy which tries to base its decisions on available empirical evidence. There is growing doubt whether the frequently used narrative approach provides a scientifically defensible way of synthesising a body of quantitative research results. The present paper demonstrates meta-analysis as a more objective and powerful alternative for this task. For this purpose evaluation data synthesised in two earlier narrative reviews on the effectiveness of work travel plans [Cairns et al. Making travel plans work: research report (former), Department for Transport, Local Government and the Regions (DTLR), London, 2002; Smarter choices—changing the way we travel. (Final report of the research project: The influence of soft factor interventions on travel demand. Research report for the Department for Transport.) London. Retrieved 1 December 2005, from , 2004] are meta-analytically re-analysed and compared with the conclusions drawn from the narrative synthesis of these data. Our meta-analyis provides only limited support for the conclusion that addressing parking is the hallmark of successful work travel plans. Our meta-analysis indicates that site and organisational factors as well as characteristics of the monitoring process are significant predictors of effective work travel plans, whereas Cairns et al. view little evidence for the impact of these factors.