提高沥青-酸性集料抗水损害的试验研究

针对酸性集料与沥青粘附性差、混合料水敏感性大的难题 ,根据配位键理论采用含铬外加剂处理酸性集料 ,显著提高沥青与酸性集料的粘附性。用强化的冻融劈裂试验评价混合料水损害 ,对比试验说明经过含铬外加剂处理后的酸性集料混合料劈裂强度比提高显著 ,长期抗水损害性能也较好。     

太原市河道覆盖及整治规划研究

阐述太原市山洪沟河及排退水渠的现状及发展 ,研讨河道及排水渠道的规划和复盖中应遵循的原则和存在的一些问题     

影响水利工程施工质量的主要因素与控制措施

在水利工程施工过程中 ,影响其质量的主要因素有“人、材料、机具、方法、环境”等五方面。一个水利工程项目从开工到竣工投入运行的施工过程中 ,只要某一环节上出现问题 ,都会影响工程质量的提高或可能埋下质量事故隐患。因此 ,保证水利工程施工质量 ,努力实现施工合同条件中确定的施工质量要求 ,必须做到事前主动控制 ,事中积极检查 ,事后严肃把关的积极的预防措施。同时 ,必须贯彻“以防为主 ,防检结合”的方针 ,做到纵向全过程、横向全系统、意识全方向、时间全控制的质量管理要求 ,综合运用多种督查手段措施 ,确保结构安全 ,满足使用功能 ,外表美观大方     

Introduction: Habitual travel choice

In this introduction to the special issue on habitual travel choice, we provide a brief account of the role of habit in travel behaviour, discuss more generally what habitual choice is, and briefly review the issues addressed in the solicited papers. These issues include how habitual travel behaviour should be measured, how to model the learning process that makes travel choice habitual, and how to break and replace car-use habits.     

Bus Priority Using pre-signals

The need to provide efficient public transport services in urban areas has led to the implementation of bus priority measures in many congested cities. Much interest has recently centred on priority at signal controlled junctions, including the concept of pre-signals, where traffic signals are installed at or near the end of a with-flow bus lane to provide buses with priority access to the downstream junction. Although a number of pre-signals have now been installed in the U.K., particularly in London, there has been very little published research into their design, operation and optimisation. This paper addresses these points through the development of analytical procedures which allow pre-implementation evaluation of specific categories of pre-signals. The paper initially sets out three categories of pre-signal, which have different operating characteristics, different requirements for signalling and different impacts on capacity and delay. Key issues concerning signalling arrangements for these categories are then discussed, together with a summary of the analytical approach adopted and the assumptions required. Equations are developed to allow appropriate signal timings to be calculated for pre-signalised intersections. Further equations are then developed to enable delays to priority and non-priority traffic, with and without pre-signals, to be estimated with delay being taken here as the key performance criterion. The paper concludes with three application examples illustrating how the equations are applied and the impacts of pre-signals in different situations.The analyses confirm the potential benefits of pre-signals, where these signals apply to non-priority traffic only. Where buses are also subject to a pre-signal, it is shown that disbenefits to buses can often occur, unless bus detectors are used to gain priority signalling.     

非自由液化场地地基动力性能大型振动台模型试验研究

基于1∶10模型大型振动台试验,研究非自由液化场地的地基动力性能。液化场地条件下,与自由场地基相比,非自由场地地基的自振频率明显加大、动力耗能作用提高较小。土层液化前且在小震输入下,地基动力变形的线性特征较突出,主要表现为对地震波的动力放大作用,加速度反应自下而上逐渐增大;土层完全液化后,地基加速度反应自下而上也逐渐增大,这是由于液化地基的层间剪切运动加快且加快的速率自下而上逐渐增大所致。地基孔压变化主要受两方面因素影响:一是随埋深减小,孔压减小,但孔压比增大;二是离桩距离越近,孔压和孔压比越大。土层液化前,输入波主要峰值过后,自下而上孔压消散逐渐减慢。较大震输入下,自下而上孔压有减小的趋势,但最大孔压比均很快达到液化孔压比;输入波主要峰值过后,孔压消散很缓慢,尤其是孔压消散随埋深减小越来越慢。试验中还出现瞬时负孔压的有趣现象,这也许是由于可液化土层发生瞬时膨胀作用所致。     

连拱隧道施工技术

针对连拱隧道的施工工艺复杂,中隔墙衬砌容易开裂和渗漏水的特点,介绍了连拱隧道的施工方法,分析了连拱隧道中隔墙衬砌容易开裂和渗漏水的原因,提出了防排水施工的方法及防治渗漏水的措施,可供类似工程施工中参考.     

地下连续墙作为桥梁基础在软土地区的应用

本文以上海浦东国际机场1号桥的设计为背景,介绍了地下连续墙做为桥梁基础的计算模型的建立、计算参数的取值以及构造处理措施。结果表明:当条件受限制时,地下连续墙不失为一种较好的基础型式。     

The desulphurisation of shipping: Past,present and the future under a global cap

As from January 2020, the International Maritime Organization (IMO) is implementing a global 0.5% limit on the sulphur content of fuel, commonly known as the global sulphur cap. This limit is the latest policy in the efforts to reduce sulphur emissions from shipping, following the designation of emission control areas (ECAs) and other regional regulations. In this paper, a literature review is conducted of academic studies that have dealt with issues relating to the reduction of maritime sulphur emissions. Various recurring research themes are identified, spanning the areas of operations research, maritime economics and transport policy. The effects and implications of available compliance options are then analyzed from the perspectives of ship operators, shippers and consumers. Using lessons learned from the enforcement of ECA regulations, this is followed by an appraisal of various potential issues related to the enforcement of these new global regulations. It is found that a homogeneous enforcement regime is required to ensure a level playing field amongst ship operators and that the global sulphur cap may lead to serious market distortion, due to the potential short term rise of fuel prices. The paper concludes with a set of recommendations for future research on sulphur emissions from shipping in the aftermath of the global cap and, looking forward, to its relationship to the IMO strategy on the reduction of greenhouse gas (GHG) shipping emissions.     

Solving the gate assignment problem through the Fuzzy Bee Colony Optimization

In the field of Swarm Intelligence, the Bee Colony Optimization (BCO) has proven to be capable of solving high-level combinatorial problems, like the Flight-Gate Assignment Problem (FGAP), with fast convergence performances. However, given that the FGAP can be often affected by uncertainty or approximation in data, in this paper we develop a new metaheuristic algorithm, based on the Fuzzy Bee Colony Optimization (FBCO), which integrates the concepts of BCO with a Fuzzy Inference System. The proposed method assigns, through the multicriteria analysis, airport gates to scheduled flights based on both passengers’ total walking distance and use of remote gates, to find an optimal flight-to-gate assignment for a given schedule. Comparison of the results with the schedules of real airports has allowed us to show the characteristics of the proposed concepts and, at the same time, it stressed the effectiveness of the proposed method.