Cruise activity and pollution: The case of Barcelona

One of the main causes of mortality worldwide is air pollution. To tackle this problem, local, regional and national governments have implemented policies to reduce emissions from industrial and on-road sources. However, when these policies are being designed, shipping emissions are often overlooked. There has been a drastic increase in the demand for cruises and its economic relevance is also growing in port-cities. Barcelona is Europe’s leading cruise port, and it is located near the centre of the city. In this context, this paper analyses the impact of cruise ships in the air quality of the entire city of Barcelona using a dataset with information about pollutants and the number of cruises arriving to the port. We show that there is a direct impact between cruises staying at the port and city pollution. Additionally, the size and age of the cruise also affect air quality. The larger (or newer) the cruise is, the higher the emission generated. Moreover, our simulations show that the whole city is affected by these emissions.     

Non-exhaust particle emissions under various driving conditions: Implications for sustainable mobility

Non-exhaust particle (NEP) emissions from road traffic contribute significantly to Particulate Matter (PM) pollution in urban areas. The primary objective herein is to develop the knowledge required to move toward more sustainable mobility. NEP emissions are studied by means of complementary experiments on chassis dynamometers, on test tracks and at the roadside. Laboratory tests demonstrate that brake wear particles (BWP) emissions can change with braking force and frequency. A brake pad temperature threshold exists, above which the rate of ultrafine particle emissions is quite high. Below this threshold, the BWP emissions are dominant in the accumulation and coarse modes. Test track measurements have demonstrated that tire-road contact particle (TRCP) emissions considerably modify the atmospheric PM background especially for the supermicron fraction. Their number size distribution highlighted an ultrafine and accumulation modes centered at about 40 nm and 200 nm, respectively. The TRCP level increases with vehicle speed and during the acceleration and deceleration phases. Roadside measurements in the urban environment confirm the presence of NEP in significant proportions, in both the accumulation and coarse modes. The chemical composition of NEP differs depending on the size mode: BWP mainly stem from the degradation of brake pad lining materials, while TRCP are a mixture of tire tread wear and re-suspended dust. The presence of Fe-rich particles nevertheless serves as a good indicator of the NEP contribution to PM at the roadside. Lastly, in considering the parameters influencing NEP emissions, a series of recommendations are offered in order to achieve a more sustainable mobility.     

Customers’ selections between premium electric taxis and liquefied petroleum gas taxis

Reducing roadside emissions is a common challenge in metropolitan cities. In Hong Kong, conventional liquefied petroleum gas taxis are one of the main contributors to roadside emissions as they operate on the streets 24 h a day with a long daily driving mileage. Moreover, these taxis suffer from a severely poor service reputation. To enhance the environmental friendliness and service quality of the taxi industry, this study explores the market potential of operating premium electric taxis in the dispatching mode. A stated preference survey was conducted to 1410 taxi customers about their taxi-riding choices between premium electric taxis and conventional liquefied petroleum gas taxis. In total, 5640 observations were obtained and used to develop a series of binary logistic regression models with different model formulations for the determination of the significant factors influencing customers’ selections. The findings indicate that walk time to and wait time for taxis were the most critical concerns to the customers, and they were more willing to take premium taxis if their journey distance was longer and their desired improvement on taxi service quality was greater. The socio-demographic status of taxi customers also influences their choices. The associated policy implications are discussed for promoting taxis with better service quality and fewer roadside emissions. The findings provide some policy insights to other international cities that have a similar taxi market to Hong Kong.     

服务质量五维度对网购顾客满意度的影响——基于兰大学生网购经验的实证研究

基于SERVQUAL多维度量表,本研究构建了一个服务质量五维度(有形性、可靠性、反应性、保证性、移情性)与网购顾客满意度之间的关系模型并提出了相应的研究假设。对过去一个月有网购经验的兰大学生进行了面对面的问卷调查,采用SPSS17.0软件对收集到的数据进行了统计分析。实证结果表明,受访者对于网上购物总体比较满意。服务质量五维度中,可靠性、反应性和保证性均对网购顾客满意度有显著的正向影响;而另外两个维度,有形性及移情性,对网购顾客满意度的影响却并不显著。网购经验对服务质量与顾客满意度的关系有显著调节作用。     

轻集料混凝土在新坝船闸启闭机房结构物中的应用

结合新坝船闸启闭机房结构物工程中轻骨料混凝土应用，探讨轻骨料及轻骨料混凝土的技术性质，以提高轻骨料砼的应用技术，拓宽轻骨料砼的应用范围。     

浅谈钻孔灌注桩常见的施工质量问题

认真总结在钻孔灌注桩施工过程中 ,影响工程质量的诸多因素、成功的经验与失败的教训 ,就提高钻孔灌注桩基础的可靠性来阐述应该采取各项完善施工的措施     

堆石混凝土砌体施工质量控制研究及实践

结合某沿河滨江路项目中堆石混凝土挡墙工程的现场试验,分别从原材料、工艺流程、试验和检测评定等环节探讨了堆石混凝土挡墙施工质量控制方法.结果表明：高比例含量的大粒径块（卵）石可以降低圬工结构水泥用量,使圬工结构的总释放热量和绝热温升显著降低,并能发挥大颗粒漂石及大块石对混凝土收缩的限制约束作用,抑制裂缝的产生与发展,从而满足施工质量控制要求.     

桥梁工程混凝土质量管理方法

简要分析影响桥梁混凝土质量的主要因素,总结桥梁混凝土质量管理方法。研究表明,保证混凝土的质量需要合理划分施工标段,严格监理,严格遵守配比和相关流程,通过第三方进行质量检测。     

地质雷达在铁路隧道混凝土衬砌质量检测中几个问题的探讨

针对近年来使用美国GSSI公司生产的SIR-3000型地质雷达检测仪从事铁路隧道混凝土衬砌质量检测过程中积累的经验以及遇到的问题,从衬砌背后空洞检测、钢筋、钢拱架检测、衬砌厚度检测和仰拱厚度检测等方面分析问题产生的原因,探讨提高地质雷达检测精度的一些措施。对于衬砌背后空洞的规模大小以及一些沿隧道环向分布的空洞,受检测条件以及现有的无损检测技术条件的限制,只能通过结合锤击法和钻芯法来综合评判; 对于钢筋、钢拱架的检测,通常双层钢筋中第2层钢筋的数量受雷达分辨率的影响很难看清,因受电磁波趋肤效应的影响,钢筋混凝土的衬砌厚度、初期支护钢拱架和初期支护空洞等的检测情况都不理想,所以务必要在隧道二次衬砌施工前完成初期支护混凝土质量及钢拱架数量的检测及整改工作; 对于衬砌厚度的检测,由于隧道衬砌介质的不均匀性,使得相对介电常数无法得出一个精准的数值,故不应该过分依赖从雷达剖面提取出来的厚度实测值,应允许一定范围内的误差; 对于仰拱厚度的检测,一般需要结合设计、施工等资料,必要时候借助钢筋的埋深位置等对仰拱厚度进行初步判断,但很多时候因受分辨率影响,检测结果往往与实际结果有较大误差,这时还需结合钻芯法来进一步确认。地质雷达检测技术的关键是做好以下几方面的工作： 建立合理的检测机制,严格工作纪律,不断优化检测方法。