Excess Commuting: A Critical Review

Abstract

The stringent ship emission regulations under IMO's (International Maritime Organization) MARPOL Annex VI are a main driver to consider liquefied natural gas (LNG) as a ship fuel. Research into LNG as a marine fuel saw a strong growth in recent years, but no study has analyzed in a systematic way the level of convergence among the findings presented in the wide range of studies. In order to fill this gap, this paper seeks to perform a systematic review to synthesize the findings of 33 published studies on the use of LNG as a ship fuel. The aim is not only to obtain a much broader understanding of the current perspectives and challenges for applying LNG as a bunker for ship propulsion, but also to identify the gaps and weak points in the literature which could suggest future research. Moreover, given the output of the synthesis, the paper presents an extensive decision-making framework for shipowners when deciding on a fuel switch for their fleet from conventional oils to LNG in order to achieve a level of conceptual development beyond that attained in individual studies. In addition, the study also identifies the important role of ports in facilitating and encouraging the large-scale adoption of LNG in the maritime industry.     

A tool for calculating aircraft emissions and its application to Greek airspace

This paper quantifies the impact of aircraft emissions on local air quality and climate change. Aircraft emissions during the cruise cycle and the landing/take-off cycle are considered. A tool is developed that computes emission values using real-time air traffic data derived from various databases. Emissions include carbon dioxide, hydrocarbons, carbon monoxide and nitrogen oxides. The overall output is a detailed ‘emissions map’ of a given territory that enables the identification of critical emission spots including routes, airports, season, aircraft type and flight category. The method can be used for real-time monitoring of airline emissions and for policy analysis. The proposed tool and resulting outputs are illustrated in the case of the Greek airport system using domestic, international and overflights. Demand volatility driven mainly by tourism and its impact on emissions is assessed.     

基于多智能体系统的单元城市交通需求特性研究

我国大城市交通、环境问题日益突出,探讨城市形态对减少交通需求的影响是一个重要课题。论述单元城市的概念,并基于多智能体系统构建自下而上的城市微观模拟系统,结合竞租理论、经济地理学、交通规划理论等学科的成果,定量研究单中心城市与单元城市在交通效率、碳排放上的区别。结果表明,对于超过一定规模的城市,单元城市在减少交通需求、节能减排上有更好的表现。模型除用于研究理想城市形态对交通、碳排放量的影响外,还可用于研究与评价实际城市规划中不同城市形态方案的交通需求。     

在用汽油车排气污染物排放现状分析

为探究在用汽油车排气污染物排放特性和超标特点,统计分析了2010年某检测中心651辆在用汽油车排气污染物检测结果数据,获取了现行标准下车辆尾气排放不合格率、排放超标类型和典型车型,分析了引发排放超标的原因和常见故障。对尾气排放超标治理具有指导作用,对实现机动车减排环保具有现实意义。     

某船用中速柴油机排放特性试验

对某船用中速柴油机的电控化改造前按推进特性进行了排放试验.试验分析结果表明:该机低转速、低负荷区CO排放浓度低,HC排放浓度高,而高转速高负荷区CO排放浓度高,HC排放浓度低;NOx排放浓度最高位于800r/min附近,而NOx比排放随转速和负荷的升高而降低,其变化趋势主要受油耗率的影响.试验结果可供相关技术人员参考.     

3600 TEU集装箱船节能改装项目的初步研究

伴随着气候问题、油价高企以及航运市场低迷的严峻形势,节能减排已成为船舶设计的重要理念,尤其是对于营运船舶的节能改装受到越来越多船东的关注.以改装现有的3 600 TEU集装箱船为例,采取降低主机功率转速、安装节能装置、优化球首线型和采用低阻油漆等方法,可取得显著节能效果.同时该研究尽可能采用高效低成本的方案,以降低改装成本,缩短成本回收周期,从而可以为船东、船厂带来最大化的收益.     

在发动机台架上模拟欧Ⅲ低温冷启动排放特性的探索

为使汽油车满足欧Ⅲ排放法规，必须解决-7℃条件下的催化器快速起燃和抑制排放物陡增的问题。作者研究设计了试验系统和探讨了模拟方法，并在台架上模拟和测试带有三效催化器的汽油车电喷发动机的低温启冷动特性。     

船用电控柴油机的排放控制技术与试验

介绍MARPOL73/78公约附则VI《防止船舶造成大气污染规则》,针对新型船用低速电控柴油机利用共轨系统控制并优化燃烧过程,采用低NOx喷嘴、延迟燃油喷射、增加压缩比、无烟运行模式等降低排放的措施与试验,结果表明船用电控柴油机的排放完全符合IMO排放规则。     

含分层损伤复合材料层合板频率响应函数分析

振动分析中含分层损伤复合材料层合板的动力特性是非常重要的，本文主要研究含分层损伤层合板的频率响应函数（FRFs)。首先，建立分层模型和基于FOSD理论的有限元层合板单元，为保证分析模型中避免出现上子板与下子板间的脱离或嵌入，引入了16节点虚拟界面罚单元，其次，根据Adams应变理论，由层合板SDC推导出相应结构振动的模态阻尼；最后，对0%-80%不同分层大小层合板的分析计算结果，讨论了不同分层大小对受损结构的固有频率，SDC和FRFs的影响，本研究不仅有助深入理解含分层复合材料层合板的动力特性，而且可发展用来预报复合材料层合板分层损伤的程度。     

汽车蒸发排放控制系统的设计

介绍了汽车蒸发排放技术的发展、控制系统的设计方法及其控制策略。经过试验证明，该系统设计可以满足法规的要求。