谈船舶应急电源的PSC检查

文中介绍了船舶应急电源系统的结构原理、公约要求，并结合工作实践讲述了系统的检查要点、常见缺陷及处理原则。     

隧道数字化火灾预警系统的在线量化评估

为检查和评价隧道及地下空间火灾预警系统的实际功能,需要一套可行的在线评估手段。根据近年来国内外全尺寸隧道火灾发展曲线的试验结果,提出隧道火情的定义依据;引用运营隧道内准分布式光纤光栅感温火灾探测器的实测数据,证明运营中隧道报警系统的个性化现象;提出合格的数字化报警系统应存在一个在统计学意义上使漏报率和误报率同时达到期望值的合理阈值取值区间;建议以该区间的尺度作为该系统功能完好性的评估指标;对日常隧道运行温度数据的统计分析可估计合理阈值取值区间的下限,对规定条件下的现场点火试验温度数据分析可估计合理阈值取值区间的上限。在隧道运营期该区间尺度可实时在线自动更新。     

Prioritizing new bicycle facilities to improve low-stress network connectivity

This paper introduces a new method to prioritize bicycle improvement projects based on accessibility to important destinations, such as grocery stores, banks, and restaurants. Central to the method is a new way to classify “bicycling stress” using marginal rates of substitution which are commonly developed through empirical behavioral research on bicyclist route choice. MRS values are input parameters representing bicycling stress associated with the number of lanes and speed limit of a street. The method was programmed as a geographic information system tool and requires commonly available data. The tool is demonstrated on three improvement scenarios that were recently proposed for Seattle, Washington. The full build-out scenario consists of 771 projects that include various new bike lanes, protected bike lanes, and multi-use trails. The tool produces priority rankings based on a project’s ability to improve low-stress connectivity between homes and important destinations. The analysis identifies specific areas and neighborhoods that can be expected to exhibit better bikeability. Transportation planners can use the tool to help communicate anticipated project impacts to decision-makers and the public.     

Performance comparison between pedestrian push-button and pre-timed pedestrian crossings at midblock: a Korean case study

Walking has been highlighted as an independent transportation mode as well as an access/egress mode to/from public transit to encourage the use of more sustainable transport systems. However, walking does not seem to have priority over other transportation modes, especially in areas where various modes of movement are in conflict. The pedestrian push-button system seems to be a solution to distribute the right of way. The focus of this study is on the performance issue of the pedestrian push-button. Specifically, this study deals with issues related to mid-block crossings and attempts to answer two questions: whose waiting time is longer at pre-timed and push-button crossings, pedestrians, or vehicles? and which system – pre-timed or push-button – is better in terms of total waiting time? According to our simulation analyses, if the pedestrian flow rate is less than 120, 85, and 70 ped/h for two-, three-, and four-lane roads, respectively, the push-button system is recommended.     

基于公路隧道内车辆对火灾影响数值研究

以武汉长江公路隧道为工程背景,利用FDS5.0数值模拟软件建立隧道实体模型,进行火灾数值模拟分析。研究不同火灾热释放率、车辆长度、火源车辆阻塞比以及附近车辆之间间距、附近车辆长度、附近车辆阻塞比6种因素下,隧道内拱顶温度和人平均身高Z=1.70 m处CO浓度的分布规律,并对这6种因素进行敏感性分析。结果表明:隧道的拱顶温度随着热释放率和阻塞比的增加而增加,随着着火车辆长度的增加而减小;Z=1.70 m处CO浓度随着火灾热释放率和车辆长度的增加而增大,随阻塞比的增大而减小;影响隧道火灾的主要因素是热释放率和车辆阻塞比,应有针对性地对这二种因素进行有效的管理。     

TBM刀具检修工艺的技术探讨

结合兰渝铁路西秦岭隧道TBM项目刀具的使用、维修、更换等过程,分析刀具检查与维修的工艺过程,对刀具拆卸检查与维修中的各注意事项进行总结。刀具的检查与维修在掘进过程中占有一定的比例,保证刀具检修的质量是TBM快速掘进的前提,刀具的使用寿命会影响TBM掘进的利用率。西秦岭TBM项目针对不同地质情况下的施工刀具维修制定了详细的检查项目,经过第1阶段刀具检查维修的实践,取得较好的成效。     

Prioritization of failure risk in subsea flexible pipes via data envelopment analysis

Risk-based inspection is nowadays the predominant approach to structural integrity assurance in complex engineering systems, such as those designed for and operated in deepwater environments. One of the major tasks in risk-based planning is risk ranking of the components comprising an engineering system. In this paper, a mathematical model based on data envelopment analysis is developed for this purpose, whereby two types of weights are employed: subjective judgmental weights which are provided as input, and objective which constitute the output of the model. The use of the mathematical model is illustrated in a real world system of subsea flexible pipes, which operational in the south Atlantic Shelf off the Southeast Coast of Brazil.     

大粒径碎石桩在桥头软基处理中的应用

大粒径碎石桩能克服由于地基强度较低而难以成桩的问题，它是超软弱淤泥地基土加固处理方法之一。实测资料得到，碎石桩复合地基承载力标准值比天然地基提高了2、8倍左右。实测沉降量比相邻段用砂井加l土工布处理，沉降量减少约30％。地基加固效果显著。实测沉降速率表明，只要大粒径碎石桩施工质量得到保证，路堤填筑期基本上可以不考虑填土速率问题。从桥头相邻两种地基处理方式沉降与沉降速率比较分析得到，碎石桩可起到缓冲过渡区的作用，可减轻桥头跳车问题。介绍了大粒径碎石桩在京珠高速公路广珠段某桥头软基处理中的应用。     

U71 Mn 50 kg·m-1普通碳素钢钢轨疲劳裂纹扩展速率试验研究

根据室内对U71Mn50kg·m-1普通碳素钢钢轨按三点弯曲标准进行的试验,测定该钢轨的疲劳裂纹扩展速率,即裂纹扩展深度a及其对应的循环次数N值。利用中值法求得裂纹扩展深度对循环次数的微分值。根据断裂理论求得相应的裂纹前沿应力强度因子幅度ΔK。根据Paris公式,对以上两值取自然对数进行线性回归分析,确定该公式中U71Mn50kg·m-1普通碳素钢钢轨疲劳裂纹扩展速率的两个材料常数C为3 8771×10-12,m为3 6343。     

构建服务型海事执法督察工作的思考

文中列举和分析了海事执法督察工作的现状和存在的问题，阐述了海事执法督察工作的内涵，并提出了建立服务型海事执法督察工作的设想。