Field and wind-tunnel study of pollutant dispersion in a built-up area under various meteorological conditions

Pollutant dispersion over a built-up area was investigated experimentally in the field and wind-tunnel experiments under different conditions of thermal stability for various wind directions using a tracer gas technique from a point source without buoyancy. Tracer gas concentration data were collected from 17 sites, including parking places, streets, open areas, and high-rise buildings, in a dense urban environment in the Hamamatsu-cho Minato-ku area, Tokyo, Japan. Concentration data were also examined in a boundary layer wind tunnel using a building-block model at a scale of 1:600. Eighty-three points were selected for measuring concentration in the wind-tunnel experiments. The concentration data measured in the wind-tunnel experiments was compared with the results of the field experiments in order to evaluate the prediction accuracy of the wind-tunnel experiments. The results of the wind-tunnel experiments showed good agreement with the results of the field experiments. The obtained results indicate that the wind direction is one of the important parameters in studying atmospheric diffusion. Moreover, these results are used to validate the corresponding computational fluid dynamics (CFD) prediction.     

基于ENVI-met模型的北京市典型道路 行道树树种优化研究

城市道路是城市居民重要的活动场所,人行道空气质量与居民健康密切相关。行道树被广泛认为会降低道路空气交换速率,从而造成道路污染物浓度升高;然而,行道树通过改变湍流形成空气颗粒物浓度差异化分布,同时对颗粒物有一定截获能力。因此,合理规划行道树有望改变道路空气流场进而改善局部空气质量。以北京地安门内大街为例,从改善道路污染的角度展开基于ENVI-met模型的行道树设计与技术探索,得出:1)ENVI-met可用于道路污染物扩散及沉降模拟研究;2)行道树冠幅是影响道路颗粒物扩散的重要因素,冠幅宽度到达道路宽度时,往往会影响颗粒物的快速扩散,导致道路颗粒物浓度升高;3)冠幅较大且冠层高度靠近地面的行道树对道路颗粒物有较好的吸附效果。本研究为行道树树种选择提供有利依据,同时也是国内首次用ENVI-met对颗粒物扩散和沉降开展研究。     

The impact of environmental factors on benthos communities and freshwater gastropod diversity in urban sinkhole ponds in roadside and forest contexts

Sinkhole ponds originated as a result of human activity leading to ground subsidence and create important habitats for the diversity of benthos fauna in urban areas. The objectives of this study were to determine whether the context (roadside/forest) is important in relation to the composition and diversity of macroinvertebrates, and to evaluate the influence of environmental factors (e.g. water quality) on snail communities. The study showed that the context of ponds had an impact on the properties of the water. Ponds located along roads were characterised by higher conductivity and a higher concentration of calcium and phosphates. The fauna was composed of 47 taxa, including 26 taxa found in both pond contexts. The density of macroinvertebrates was higher in forest ponds. CCA analysis showed that conductivity and concentration of nitrates were most strongly associated with the distribution of gastropods. Alien snail species more often inhabited the roadside ponds.     

On the behaviour of open-topped oil storage tanks in high winds. Part I. Aerodynamic aspects

Measurements are presented of the mean, r.m.s. and spectral components of the pressure distribution over the surfaces of an open-topped oil storage tank, derived from experiments on a 1/250 scale model immersed in a wind-tunnel simulation of an atmospheric boundary layer. In qualitative terms it is shown how the principal features of the pressure-distribution statistics are linked to the gross features of the air flow in the immediate vicinity of the tank. By comparing these results with data from other sources, some indications are given as to how changes in the structure itself and in the structure of the incident air flow affect the pressure distribution and air flow near the tank.     

城市住区室外通风与空气负离子浓度评测研究

选取合肥市东南区域典型居住区为研究对象,运用CFD数值模拟和室外实地观测相结合的研究方法,量化模拟了夏冬两季住区室外环境的风速图,并分析了其模拟通风状况;在此基础上得到了住区内不同环境的通风特征,包括建筑布局、空间形态、建筑密度、交通路网、植物绿化等对通风的影响;再根据模拟参数,在住区内选取样点实地观测了不同环境特征下的住区夏冬两季的空气负离子和风速、温度、相对湿度以及空气正离子等数据,探索了住区室外环境中空气负离子浓度与风速、温度、湿度和空气正离子之间的相关关系。同时进一步整理了近4万个有效数据应用于空气负离子和风速的时空分布研究,推导出夏季风速与空气负离子的线性回归方程,并运用偏相关分析,得出城市住区环境中空气负离子与风速呈极显著负相关,给出了线性回归方程Y=-0.001X-0.003。最后结合建筑布局的组合、开敞空间的设计和线性道路的组织等分析了空气负离子和风速的分布规律,用以说明评价住区室外环境通风状况的可行性,为今后城乡规划和建筑设计提供科学依据和设计思路。     

Agricultural landscapes

Estimates of the levels of atmospheric pollution may be made by recording the presence or absence of common sensitive indicator species. The results of a simple survey might extend the range of plant material thought to be suitable for use in an urban area. Research by the author suggests however that some of the sensitive indicator species used seem to respond not only to sulphur dioxide but to proximity to busy roads, and there may be implications not only in the use of airpollution indicator species near roads, but in terms of roadside environmental conditions in general.     

Traffic pollution and roadside plants

Estimates of the levels of atmospheric pollution may be made by recording the presence or absence of common sensitive indicator species. The results of a simple survey might extend the range of plant material thought to be suitable for use in an urban area. Research by the author suggests however that some of the sensitive indicator species used seem to respond not only to sulphur dioxide but to proximity to busy roads, and there may be implications not only in the use of airpollution indicator species near roads, but in terms of roadside environmental conditions in general.     

不同生境行道树香樟生长特性及其对冰雪灾害的响应研究

随着全球气候变化加剧,各地极端气候现象频发,如何有效应对极端气候对城市绿化的影响是当前城市建设需要深入思考的问题。以2018年1月末南昌持续4天的极端冰冻灾害天气为契机,通过对典型样地的遴选和样地调查,对行道树及其生境的相互适应关系,以及其对冰冻灾害的响应机制做出分析,结果表明:1)行道树与道路宽度、株行距、路侧建筑等空间环境有密切关系,树木的生长受到道路空间形态的限制,并反映出相应的形态适应性;2)由于竞争促进作用,香樟长势背阴环境优于阳面环境;3)背阴环境中的香樟遭受冰雪灾害的损害程度较阳面严重,树冠的优势方向折枝较严重。     

Indoor/outdoor relationships of carbon monoxide and oxides of nitrogen in domestic homes with roadside, urban and rural locations in a central Indian region

Indoor air quality (IAQ) has been a matter of public concern these days whereas air pollution is normally monitored outdoors as part of obligations under the National air quality strategies. Much little is known about levels of air pollution indoors. Simultaneous measurements of indoor and outdoor carbon monoxide (CO) and oxides of nitrogen (NO and NO2) concentrations were conducted at three different environments, i.e. rural, urban and roadside in Agra, India, using YES - 205 multigas monitor during the winter season, i.e. October 2002-February 2003. A statistical correlation analysis of indoor concentration levels with outdoor concentrations was carried out. CO was maximum at roadside locations with indoor concentrations 2072.5 +/- 372 p.p.b. and outdoor concentrations 1220 +/- 281 p.p.b. (R2 = 0.005). Oxides of nitrogen were found maximum at urban site; NO concentration was 385 +/- 211 and 637 +/- 269 p.p.b. for indoors and outdoors respectively (R2 = 0.90792), where as NO2 concentration was 255 +/- 146 p.p.b. for indoors and 460 +/- 225 p.p.b. for outdoors (R2 = 0939464). Although indoor concentration at all the houses of the three sites have a positive correlation with outdoor concentration, CO variation indoors was very less due to outdoor sources. An activity schedule of inside and outside these homes were also prepared to see its influence and concentrations of pollutants. As standards for indoor air were not available for the Indian conditions these were compared with the known standards of other countries, where as outdoor concentrations were compared with the standards given by the Central Pollution Control board, which shows that indoor concentrations of both NO(x) and CO lie below permissible limits but outdoor concentrations of NO(x) cross the standard limits. PRACTICAL IMPLICATIONS: 'India currently bears the largest number of indoor air pollution (IAP) related health problems in world. An estimated 500,000 women & children die in India each year due to IAP-related cause--this is 25% of estimated IAP-related deaths worldwide. This study will be useful for policy makers, health related officials, academicians and Scientists who have interest in countries of developing world'.     

Location of air intakes to avoid contamination of indoor air: a wind tunnel investigation

The location of air intakes is of prime importance in buildings that are situated in close proximity to busy urban roads. If intakes are placed where the concentration of traffic pollution is high then indoor air concentrations can reach similarly high levels. This paper presents the findings from a wind tunnel investigation into the dispersion of a simulated traffic pollutant in a 1:100 scale model. The concentrations at different points on a building in the model are measured and a comparison with full-scale data is made.     

基于多源大数据与深度学习的道路视觉 特征与骑行流量相关性研究

伴随着市民慢行需求的不断增长,在国家的大力倡 导下,城市慢行系统建设得到迅速发展。而现有关于城市慢行 系统的研究中,针对道路视觉特征与骑行流量的相关性研究较 少,骑行道路的建设预评价缺乏科学的数据支撑。以北京市海 淀区5类可供骑行的市政道路为研究对象,基于全景静态图数 据,结合深度学习方法对道路的绿景指数、街道开敞度、建筑 比及界面围合度4项视觉特征进行量化,并利用开源运动数据 Heatmap获取道路对应的骑行流量,对视觉特征与骑行流量 之间的关系展开相关性研究。研究发现：在各类道路中,绿景 指数与建筑比均与骑行流量呈正相关,而随市政道路级别升 高,街道开敞度则与骑行流量由正相关逐渐转为负相关。研究 结果可以为基于骑行使用的道路建设或改造及相关绿道规划设 计提供依据。     

城市道路绿化规划与设计

针对城市道路绿化的重要性,阐述了城市道路绿地总体设计,根据道路种植设计原则,系统归纳了城市道路绿化的规划与设计要点以及植物的选择,通过绿化设计,以期达到美化街景、净化空气、保护路面、维护交通的目的。     

Long-term personal exposure to traffic-related air pollution among school children, a validation study

Several recent studies suggest an association between long-term exposure to traffic-related air pollution and health. Most studies use indicators of exposure such as outdoor air pollution or traffic density on the street of residence. Little information is available about the validity of these measurements as an estimate of long-term personal exposure to traffic-related air pollution. In this pilot study, we assessed outdoor and personal exposure to traffic-related air pollution in children living in homes on streets with different degree of traffic intensity. The personal exposure of 14 children aged 9-12 years to 'soot', NO(x) (NO and NO(2)) was assessed in Amsterdam between March and June 2003. Each child's personal exposure was monitored during four repeated 48-h periods. Concurrently, in- and outdoor NO(x) measurements were carried out at the school and at the home of each participating child. Measurements were supplemented by a questionnaire on time activity patterns and possible indoor sources. Flow-controlled battery operated pumps in a made-to-fit backpack were used to sample personal exposure to 'soot', determined from the reflectance of PM(2.5) filters. Exposure to NO(x) was assessed using Ogawa passive samplers. Children living near busy roads were found to have a 35% higher personal exposure to 'soot' than children living at an urban background location, despite that all children attended the same school that was located away from busy roads. Smaller contrasts in personal exposure were found for NO (14%), NO(2) (15%) and NO(x) (14%). This finding supports the use of 'living near a busy road' as a measure of exposure in epidemiological studies on the effects of traffic-related air pollution in children.     

全预混热风发生器燃烧特性研究

对全预混燃烧热风发生器进行燃烧实验,观察到该热风发生器的CO、NOx排放浓度都很低,通过对实验数据及误差进行分析,得出了CO、NOx的排放浓度和热风温度与热负荷和风量的关系,即CO、NOx的排放浓度随着风机风量的增大而减小,随着热负荷的增大而上升;一定风机风量下,热风温度随着热负荷的增大而增大,一定热负荷下,热风温度随着风机风量的增大而降低。     

污水源热泵系统应用的节能减排分析

介绍了污水源热泵系统的工作原理及研究现状,以长沙市城市污水实测数据为例,精确计算了长沙市城市污水中可利用的能量,定量比较了污水源热泵系统与空气源热泵系统的节能性能,计算分析了污水热能回收系统的环保性能指标.研究表明:长沙市城市污水中储存的可利用冷(热)量很高;在相同的供热量和制冷量的条件下,污水源热泵空调系统比空气源热泵系统更节能;采用污水热能回收系统,CO2、SOx、NOx、粉尘等4种污染物的削减量特别大,对减轻大气污染具有很显著的效果.由此认为在长沙地区应用污水源热泵系统有明显的节能减排效果.     

宜宾市城市道路绿化配置设计分析

通过宜宾市城市道路绿化配置设计的分析和概括,体现了道路绿化对城市园林景观和城市绿化美化的作用,以及道路绿化配置的基本原则,重点阐述了各级道路绿化配置的设计要点,对城市环境特色的创造有着积极作用。     

Influence of injection parameters on NOx emission from biodiesel powered diesel engine by Taguchi technique

ABSTRACT

This paper studies the effect of injection parameters on reduction of nitrogen oxide (NOx) emission in a multicylinder diesel engine using Taguchi orthogonal array. To obtain good performance in experiments, we have employed L9 Taguchi array on mixed level fractional design. The engine is fuelled with corn oil methyl ester biodiesel. From the experiment validation, it is found that the urea concentration and the spray angle reduce the production of NOx in the diesel engine. However, it is found that the mixing length does not support the diminution of NOx emission effectively. Additional, ANOVA outcome also reveals that the urea flow rate, urea concentration and the spray angle plays an imperative role in the reduction of NOx emission. The values of the experiments are in accordance with the Taguchi technique.     

基于城市空间规划设计视角的颗粒物空气污染控制策略研究综述

颗粒物空气污染是世界各国在快速城镇化过程中共同面临的严峻挑战。借助CNKI和Web of science,通过文献查阅整理城市空间在颗粒物污染方面的研究,系统性地总结该研究领域的整体特征与调节颗粒物污染的城市空间规划设计策略。结果显示:1)该研究属于一个新兴而前沿的学术领域,近年来呈持续上升趋势,相关文献主要来自中国、美国、英国与德国;2)绿色空间通过城市尺度的风道网络、绿地系统规划,街区尺度的公园绿地、湖泊湿地、道路绿带、城市森林对颗粒物污染产生消减作用;3)灰色空间通过城市尺度的城市形态优化、土地利用布局、街区尺度的街谷空间改造降低颗粒物污染;4)遥感反演与数值模拟技术(WRF、CFD)为规划设计策略提供技术支撑。最后对已有研究成果进行总结,并提出研究展望。     

Truncated vortex generators for part-depth wind-tunnel simulations of the atmospheric boundary layer flow

A modified design of the ‘Counihan’ vortex generator was proposed for purposes of part-depth atmospheric boundary layer (ABL) wind-tunnel simulations. Three redesigned vortex generators were manufactured and their applicability was tested in a boundary layer wind tunnel together with a castellated barrier wall and a fetch of roughness elements. Using this hardware, neutrally stratified ABL developing above rural, suburban and urban terrains was successfully reproduced. A hot-wire anemometry system was applied for measurements of mean velocity and velocity fluctuations. Comparisons of wind-tunnel results with full-scale data and/or with theoretical models are presented, including mean velocity, turbulence intensity, integral length scale of turbulence and power spectral density of velocity fluctuations. The analysis of obtained results indicates the adequacy of redesigned ‘Counihan’ vortex generators for part-depth ABL wind-tunnel simulations, as the obtained wind-tunnel results compare well with the full-scale rural, suburban and urban ABL.     

龙湖·礼嘉公园

该项目可被比作是关于场所精神、人文主义和文脉主义在中国城市建设大潮之中所泛起的浪花。地处长江和嘉陵江交汇处的滨江之城——重庆市,在恒久的岁月长河中逐渐崭露头角,经历了快速的城市发展后,已成为极具潜力的城市。嘉陵江畔的礼嘉镇也伴随着两江新区的确立而兴起。如若没有大规模的城市建设,这里还是一块无名的江坡,但是城市发展让这块场地有了向世人展示其独特魅力的机会。该项目正是在这样的契机下孕育而生的。