Memoryless Reigns of the “Sons of Heaven”

Human lifetimes have increasing failure rates; as people age (beyond early childhood) they are more likely to die. Viewing the succession of Chinese Emperors as a statistical ensemble we show that, unlike lifetimes, their reigns ceased at a constant rate for over two millennia, unaffected by elapsed time. In fact reign lengths of the “Sons of Heaven”, as the Chinese Emperors were known, followed a memoryless exponential distribution with a 10-year half-life. Becoming emperor not only influenced the duration of remaining life, but length of rule was independent of age at ascent. We propose an explanation for the observed exponentiality using asymptotic results from the theory of stationary stochastic processes.     

南水北调中线穿黄隧道盾构注浆浆材试验

为满足南水北调中线工程穿黄隧洞盾构施工工法要求,对研制开发的水泥-膨润土-水玻璃系双液塑性壁后注浆材料,通过室内模拟注浆试验,重点探讨了材料组分对注浆材料流动性、稳定性、凝胶特性、强度等性能的影响.结果表明:凝胶时间可控制在10 s左右;不同配比注浆材料1 h单轴抗压强度为0.08～0.12 MPa,28 d为7.81～8.52 MPa;渗透系数为2.0×10-8 cm/s;模拟注浆时浆液不被水稀释,充填良好;且不会对地层产生劈裂,也不会向开挖掌子面渗漏.     

跨河桥梁防洪影响评价指标体系及影响防治措施研究

针对跨河桥梁防洪影响评价中普遍存在的问题,结合近年来的工程实践经验,通过对建立跨河桥梁防洪影响评价基本框架和指标体系的研究,就跨河桥梁防洪影响的评价内容、评价指标、评价计算方法进行系统的总结分析,并就相关影响给出常见的防治措施,与广大工程设计人员商榷,为今后开展评价工作提供参考。     

Illegal mid-block pedestrian crossings in China: gap acceptance,conflict and crossing path analysis

China has experienced unprecedented economic growth and changes in urban form in the past decades. Increased urbanisation and motorisation puts pedestrians and automobiles at greater conflict. Because of China's long urban blocks (superblocks), many conflicts occur mid-block at informal or illegal crossings. This study focuses on factors influencing mid-block crossing and gap acceptance. We remotely observed illegal mid-block crossing of a six-lane urban arterial in Kunming, China, tracking 522 accepted gaps and 152 rejected gaps in a two-stage crossing (roadside to median and median to roadside). We fit a probit discrete outcome model to the data to estimate environmental determinants of gap acceptance (and rejection) behaviour, including gap size, vehicle speed, time waiting and gap lane position. We also estimate a conflict model, focusing on parameters that influence the probability of vehicle speed changes or lane deviations.     

南水北调中线穿黄隧洞关键技术问题研究

南水北调中线穿黄隧洞施工中存在着地质条件差、工程结构复杂等问题,因此施工难度很高。结合实际施工特点和技术研究应用,介绍了地连墙技术、盾构始发加固技术、盾构施工技术、内衬混凝土施工技术、隧洞防渗等几项关键技术。     

桥梁工程首级控制网测量关键技术探讨

首级控制网测量是桥梁工程顺利对接的关键技术之一，为保证桥梁工程施工质量,必须建立高精度控制网。根椐国家测量规范要求,结合某桥梁工程实例，探讨了首级控制网布设过程中的布网要求,以及平面控制测量和高程控制测量的关键技术及方法。经工程检验,该控制网布测方法能有效满足工程精度要求，对类似工程具有较强的操作性和借鉴意义。     

外加电流阴极保护技术在跨海大桥耐久性设计中的应用推广

结构的耐久性能一直是工程界研究的一个主要问题,在跨海大桥的耐久性设计方面,在国内,目前普遍选择牺牲阳极法作为阴极保护方法,而在国外跨海大桥的防腐保护中,外加电流法已经成为一种最常用的阴极保护方法。本文着重介绍外加电流法的基本原理及在杭州湾跨海大桥中的应用,供其它跨海大桥及港口工程参考。     

Introducing experiment in pedestrian behaviour and risk perception study at urban level crossing

Given the high risk of severe accidents at level crossings (LCs), this study examined legal and illegal crossings by pedestrians and cyclists at a high-traffic LC in Zagreb, Croatia. Survey data and field observations were collected to identify reasons for risky behaviour. Behaviour was observed under normal conditions and in the presence of various safety measures in order to identify measures that can reduce risky behaviour. Results show that the presence of police officer at the LC was most effective at reducing illegal crossings, while the presence of cameras contributes significantly as well, especially after safety educational campaign when illegal crossing decreases for 59.23%. We can assume that in future the improvement regarding human behaviour on LC could be made with cameras on LC and more frequent educational campaigns. This is the first reported use of field survey and video surveillance methods to analyse user behaviour at LCs in Croatia.     

单向通行对交叉口交通效果的影响

采用单向交通的策略缓解城市现有道路网络交通压力是近年来道路交通发展的一大趋势。然而,关于单向交通产生效果的定量分析却十分少见。文章从双向交通与单向交通两种不同情况下分别对同一固定交叉口展开研究,通过对比两种情况下交叉口复杂程度、通行能力等的不同,得出在城市道路中实行单向交通有着不可小觑的优越性。     

管道穿河埋深综合判定

管道穿河的埋深问题一直是岩土工程勘察的重点问题,埋深过浅会导致洪水来临时,管道被冲刷露出,造成安全问题;埋深过深会增加不必要的经济浪费。但是对于埋深计算,一直没有相关规范出台,实际应用中多是相关经验公式粗略估计。这些经验公式常由于假设或使用条件的限制,存在较大的差异。在综合考虑各公式计算前提的基础上,评判该前提条件对计算结果的影响,并依此锁定埋深计算的上下限之间的差值,为最终可靠的断定埋深提供了重要的参考。