Experimental investigation of the strength and stability of submarine pressure hulls with and without artificial corrosion damage

A submarine may have to operate for a period of time with local corrosion damage in the pressure hull if a suitable repair method is unavailable or too expensive for implementation. This paper describes collapse tests on twenty ring-stiffened aluminium cylinders, which were conducted to study the effect of corrosion damage on hull strength and stability. Artificial hull thinning was found to reduce the collapse strength of experimental models through high local stresses in the corroded region, leading to early onset of yielding and inelastic buckling. Bending associated with the eccentricity due to one-sided thinning was found to further increase the local stresses in the hull. Overall collapse pressures were more severely affected by corrosion damage than interframe collapse pressures. The percentage reduction in overall collapse pressure, compared with intact experimental models, was found to be closely related to the percentage depth of thinning. The accuracy of conventional collapse pressure predictions for the experimental models was significantly better for intact than for corroded cylinders.     

The statistical analysis of crash-frequency data: A review and assessment of methodological alternatives

Gaining a better understanding of the factors that affect the likelihood of a vehicle crash has been an area of research focus for many decades. However, in the absence of detailed driving data that would help improve the identification of cause and effect relationships with individual vehicle crashes, most researchers have addressed this problem by framing it in terms of understanding the factors that affect the frequency of crashes – the number of crashes occurring in some geographical space (usually a roadway segment or intersection) over some specified time period. This paper provides a detailed review of the key issues associated with crash-frequency data as well as the strengths and weaknesses of the various methodological approaches that researchers have used to address these problems. While the steady march of methodological innovation (including recent applications of random parameter and finite mixture models) has substantially improved our understanding of the factors that affect crash-frequencies, it is the prospect of combining evolving methodologies with far more detailed vehicle crash data that holds the greatest promise for the future.     

论香港地下空间开发的规划、立法与发展经验

 海滨城市香港山多平地少,土地是极为稀少的资源,但山岭地貌和坚硬晶质火成岩岩体很适合开发地下洞室和隧道。20世纪70年代、80年代起,就开始考虑发展地下空间,以满足都市发展的需求。为此,政府开始有计划地进行工程可行性研究,并进行相关的立法工作,为规范地下空间的开发,建立了一套完整的地下空间开发体系。结合工程实例,就香港地下空间开发的研究、规划、开发、管理和立法作简要介绍。     

Rail-truck multimodal freight collaboration: a statistical analysis of freight-shipper perspectives

Due to the effects of congestion, capacity reduction of truck-freight carriers, growing freight transportation demand, and increasing social and environmental concerns, there is a critical need for freight shippers to improve shipping quality and reduce transportation costs. Rail-truck multimodal freight collaboration can potentially address this need. In this study, we explore freight-shipper perspectives relating to the factors that may foster or impede their usage of rail-truck multimodal freight collaboration services, and the correlations of their operational and behavioral characteristics with these factors. The study provides insights to rail and truck carriers on collaboration mechanisms that can address the needs of freight shippers, including adopting synergistic technology to improve in-transit visibility, accommodating non-containerized cargo, improving the transshipment process, designing service quality control strategies, and constructing investment and revenue-sharing plans.