Influence of in-tunnel environment to in-bus air quality and thermal condition in Hong Kong

In this study, the potential exposure of bus commuters to significant air parameters (CO(2), CO and RSP) and thermal environment (air temperature and relative humidity) when buses traveled through tunnels in Hong Kong was investigated. It was found that air-conditioned buses provided a better commuting environment than non-air-conditioned buses. The blate increasing trend was found on air-conditioned buses as the in-bus air parameters concentration levels rose slowly throughout the traveling process. In contrast, the in-bus environment varied rapidly on non-air-conditioned buses as it depended on the out-bus environment. The measured in-bus CO concentration was 2.9 ppm on air-conditioned buses, while it was 4.6 ppm (even reaching the highest level at 12.0 ppm) on non-air-conditioned buses. Considering the in-bus thermal environment, air-conditioned buses provided thermally comfortable cabins (about 24 degrees C and 59% of relative humidity). However, on non-air-conditioned buses, the thermal environment varied with the out-bus environment. The mean in-bus air temperature was about 34 degrees C and 66% of relative humidity, and the in-bus air temperature varied between 29 and 38 degrees C. Also, the lower-deck to upper-deck air parameters concentration ratios indicated that the vertical dispersion of air pollutants in tunnels influenced non-air-conditioned buses as higher air parameters concentration levels were obtained on the lower-deck cabins.     

Mobility Niches: Jitneys to Robo-Taxis

Compared with many developing cities, urban travel choices are rather restricted in the United States, prompting most people to drive. Recently retired from the urban planning faculty at the University of California, Berkeley, Cervero draws from both personal experiences and 3-plus decades of research in making a case for opening America’s mobility marketplace to free-market forces, all the more important in this age of information technology and smart apps. It is argued that a rich mix of mobility options would take form as a result, ranging from smart jitneys to station cars and automated shuttles, that would better serve America’s increasingly diverse traveling public. The emergence of a host of microtransit services in recent years, like shared ride hailing and upmarket private minibuses, bears this out. More transportation choices and new mobility niches, experiences show, can give rise to less wasted and more judicious travel. Traditional urban carriers like public buses and metered taxis can also benefit from a more open, technology-informed mobility marketplace.     

基于客运交通流的长江三角洲功能多中心结构研究

选取长江三角洲城市间每日公路长途客运班次和高速铁路每日经停班次作为城市间客运交通流的替代数据,从联系强度和节点关系两个方面对长三角城市区域功能多中心结构的特征及演化趋势进行解析。认为在长三角城市区域层面,南北两翼的城市间联系网络相对独立,两翼城市与上海的联系以及两翼内部城市间的联系均呈现出北强南弱的现象,这一现象与南、北两翼产业发展的总体特征和升级路径具有较强的相关性。上海作为长三角的核心枢纽,南京、杭州、宁波作为长三角次级枢纽的格局较为清晰,苏州、南通和无锡作为上海大都市区的直接腹地甚至通勤区的态势进一步显现。随着高速铁路的发展完善,长三角城市区域"等级+网络"的演化趋势日益明显,一方面上海的极化趋势进一步增强,与此同时整个区域产业发展与基础设施的发展将呈现出进一步均衡的态势。     

Liberalisation,urban governance and gridlock: Diagnosing Yangon's mobility crisis

The city of Yangon is home to over 5 million people, hosts Myanmar's largest port and produces a disproportionate share of national output. But a mobility crisis is undermining the city's economic potential and contributing to a deteriorating quality of life for its residents. The most obvious symptom of this crisis is acute traffic congestion. The proximate causes are clear: growing demand for journeys, a surge in vehicle numbers, a modal shift away from buses, and myriad ‘flow disruptions’. However, solving this mobility crisis requires recognizing the underlying causes, including a ‘congestion incentive spiral’ fuelled by rapid liberalisation of vehicle imports in a context where there are few viable alternatives to buses and private automobiles. This situation is a direct consequence of systematic failures in urban planning, investment and regulation linked to active neglect from successive military regimes and dysfunctional institutional arrangements. To preserve its rich urban heritage, Yangon will need to embrace 21st century integrated planning practices that seek to maximise accessibility and mobility for all people rather than minimise traffic congestion for those who use cars.     

上海公共汽车的发展趋势

分析了上海目前的公共交通仍应以公共汽车为主,新型公共汽车应是柴油机化、后置发动机,并配置适量的空调车。     

高层建筑消防防火排烟设计研究

随着社会的飞速发展,高层建筑的数量与日俱增,高度也是越来越高,功能也越来越多样化,再加上部分微小型公司的入驻,使人流量和物资堆积越来越密集。大部分高层建筑内部结构复杂,甚至存在私自改建(如隔断)的情况,虽为人们带来一定的便利,但其建筑特点会引起许多潜在的消防隐患,一旦发生火灾,可为救援工作带来巨大困难。防火排烟是高层建筑消防措施中的重要组成,通过隔离明火和烟雾,可一定程度上为受困人员争取救援时间,且在火灾刚发生时,可通过防火排烟设置,争取疏散时间,最大程度降低财产损失,保障人员生命安全。因此,必须重视高层建筑防火排烟设计,优化建筑设计水平,消除安全隐患。     

A case study of real-world tailpipe emissions for school buses using a 20% biodiesel blend

Numerous laboratory studies report carbon monoxide, hydrocarbon, and particulate matter emission reductions with a slight nitrogen oxides emission increase from engines operating with biodiesel and biodiesel blends as compared to using petroleum diesel. We conducted a field study on a fleet of school buses to evaluate the effects of biodiesel use on gaseous and particulate matter fuel-based emission factors under real-world conditions. The field experiment was carried out in two phases during winter 2004. In January (phase I), emissions from approximately 200 school buses operating on petroleum diesel were measured. Immediately after the end of the first phase measurement period, the buses were switched to a 20% biodiesel blend. Emission factors were measured again in March 2004 (phase II) and compared with the January emission factors. To measure gaseous emission factors we used a commercial gaseous remote sensor. Particulate matter emission factors were determined with a combination of the gaseous remote sensor, a Lidar (light detection and ranging), and transmissometer system developed at the Desert Research Institute of Reno, NV, U.S.A. Particulate matter emissions from school buses significantly increased (up to a factor of 1.8) after the switch from petroleum diesel to a 20% biodiesel blend. The fuel used during this campaign was provided by a local distributor and was independently analyzed at the end of the on-road experiment. The analysis found high concentrations of free glycerin and reduced flash points in the B 100 parent fuel. Both measures indicate improper separation and processing of the biodiesel product during production. The biodiesel fuels used in the school buses were not in compliance with the U.S.A. ASTM D6751 biodiesel standard that was finalized in December of 2001. The U.S.A. National Biodiesel Board has formed a voluntary National Biodiesel Accreditation Program for producers and marketers of biodiesel to ensure product quality and compliance with the ASTM standard. The results of our study underline the importance of the program since potential emission benefits from biodiesel may be reduced or even reversed without appropriate fuel quality control on real-world fuels.     

Particle and gaseous emissions from compressed natural gas and ultralow sulphur diesel-fuelled buses at four steady engine loads

Exhaust emissions from thirteen compressed natural gas (CNG) and nine ultralow sulphur diesel in-service transport buses were monitored on a chassis dynamometer. Measurements were carried out at idle and at three steady engine loads of 25%, 50% and 100% of maximum power at a fixed speed of 60 km h^− 1. Emission factors were estimated for particle mass and number, carbon dioxide and oxides of nitrogen for two types of CNG buses (Scania and MAN, compatible with Euro 2 and 3 emission standards, respectively) and two types of diesel buses (Volvo Pre-Euro/Euro1 and Mercedez OC500 Euro3). All emission factors increased with load. The median particle mass emission factor for the CNG buses was less than 1% of that from the diesel buses at all loads. However, the particle number emission factors did not show a statistically significant difference between buses operating on the two types of fuel. In this paper, for the very first time, particle number emission factors are presented at four steady state engine loads for CNG buses. Median values ranged from the order of 10¹² particles min^− 1 at idle to 10¹⁵ particles km^− 1 at full power. Most of the particles observed in the CNG emissions were in the nanoparticle size range and likely to be composed of volatile organic compounds The CO₂ emission factors were about 20% to 30% greater for the diesel buses over the CNG buses, while the oxides of nitrogen emission factors did not show any difference due to the large variation between buses.     

翼缘削弱钢梁(RBS)构件的受力分析和设计

对 2 0世纪 90年代几场大地震后的钢结构震害调查发现 ,以往抗弯框架的刚性连接方式并不能达到人们所预期的目的 ,甚至有较大的破坏。在此基础上 ,提出了采用翼缘削弱钢梁 (RBS)的构造方式 ,来达到强柱弱梁的抗震目的。通过对以往大量试验和数值分析结果的研究 ,结合现行规范和工程实际要求提出了采用RBS的计算方法和构造方式     

从零开始,基于不同生活范围内“绿”的思考

城市中人们通过不同的交通方式所进行的公共活动范围有很大区别,停留在家、步行、自行车和电动车、小汽车和公交车等都影响了人们的生活范围。文章对这四个层次内公共空间该如何营造进行思考,针对几种城市设计中的细节提出其想法和意见。