Characterization of visibility and atmospheric aerosols in urban, suburban, and remote areas

Visibility data from over the past four decades accumulated from urban areas of central Taiwan indicated that air pollutants have significantly degraded visibility in recent years. Currently, the annual average visibility in urban areas of the same region is approximately 8-10 km, while the visibility in remote areas is approximately 25-30 km. To understand how aerosols affect the visibility in this region, here we selected three sites in central Taiwan to measure the soluble ionic and carbonaceous species of PM(2.5) and PM(2.5-10) during 1997-1998. A MOUDI cascade impactor was used to measure the size distributions of atmospheric sulfate, nitrate, and carbonaceous particles. The aerosol data were then analyzed together with meteorological and air quality data. Comparing the results obtained from urban, coastal suburban and remote sites revealed that sulfate, carbonaceous species and local wind speed significantly affected the visibility in the urban area. However, sulfate concentration and humidity influenced visibility in the coastal area of central Taiwan. The particulate concentration at the remote station was roughly one-fifth of that in the city. Regression analysis results indicated that humidity is a dominant factor affecting remote visibility.     

城市非建设用地对雨洪管理的影响

针对城市的防洪排涝控制、雨水安全排放等问题,探讨了如何构建高效的雨洪控制管理体系,详细介绍了城市雨洪管理的三种模式及自然水体在城市雨洪管理中的地位,并分析了LUCC对城市水安全问题的影响因素,以从根本上减少城市水安全问题。     

Transport in an urban context

There are three distinct kinds of problems with which the urban transport planner has to deal. Congestion is the one to which both analytical and policy making effort have been traditionally directed. More recently environmental objectives and a concern for the transport facilities available to disadvantaged groups have been given a higher priority. Unfortunately, neither of these objectives is adequately catered for by standard analytical methods or transport planning instruments and recent analytical and institutional developments embody attempts to rectify this defect. But the task of converting good intentions in these respects into good policies is complex and some of the apparently obvious solutions, such as public transport subsidy, may even be counterproductive. It would be unwise to expect any cheap and easy solutions to the problems to emerge.     

城区照明

Hess的投影反射系统具有光点影像分离功能。这个系统的照明光线不眩目．从根本上加强了街道和广场的气氛。新增的“Devio”墙体安装照明设备用于提供不对称光线。这种在墙上安装的型号可应用于三种多面系统：可用于街道照明、区域照明和辅助立面照明。为满足灯具数量不断增长的需要，Hess也设计了带有多个投影仪的设备模型。     

Sustainable urban growth in peripheral areas

The monograph addresses the factors affecting the degree of sustainability exhibited by population growth in peripheral urban settlements. Development differentials between core and peripheral regions in countries of different size and various level of economic development are discussed and specifically, the following issues are considered: 1, core versus periphery: inequalities and development needs; 2, development peculiarities of peripheral urban settlements; 3, criteria for sustainable urban growth; 4, factors influencing urban growth in peripheral areas; and 5, planning strategies for regional development. Two major theoretical considerations are posited for discussion. First, that ‘sustainable population growth' of an urban settlement is defined according to the settlement's ability to attract newcomers and retain current residents (migration attractiveness). Second, that the preconditions which are essential for sustainable population growth in peripheral areas are not identical to those in the core. A set of analytical models designed to explain development peculiarities of peripheral settlements are suggested and several planning strategies are also proposed, aimed at enhancing the socio-economic sustainability of existing settlements in peripheral areas. These include: 1, the formation of compact development clusters; 2, the concentration of state and local financial resources on selected development settlements; 3, the adoption of a system of progressive economic incentives to promote private investment in peripheral areas; and 4, stricter regulation of land use in core regions.     

Understanding chronic poverty in urban areas

The problem of chronic poverty in urban areas has been given little attention despite an increasing interest in poverty and some recognition of the growing significance of urban populations. This paper reviews the literature to bring together what we know about the nature and scale of chronic poverty in urban areas. It begins with a consideration of the definition of chronic urban poverty and related issues of poverty measurement. The section also reports on some recent assessments of the scale and scope of urban poverty. Following sections report on the different nature of such poverty in specific kinds of urban settlements (small towns, urban peripheries and the inner city) and social groups that appear to be particularly vulnerable. The paper concludes by drawing out some of the factors that appear to be of significance in understanding the causes of chronic poverty in urban areas.     

Impact of non-uniform urban surface temperature on pollution dispersion in urban areas

Airflow pattern through street canyons has been widely studied to understand the nature of pollution dispersion in order to develop guidelines for urban planners. One of the major contributing parameters in pollution dispersion is thermal-induced flow caused by surface and air temperature difference. However, most of the previous studies assumed isothermal condition for street canyons. Those addressed the thermal-induced flow, have assumed a uniform wall surface temperature distribution. The external building wall surface temperature distribution is not uniform, and is influenced by many factors including the wall surface characteristics, and shading. The non-uniform temperature distribution significantly impacts on 3-dimensional airflow within street canyons. Moreover, effect of intersection is barely considered in the literature where L/H<3 (L and H are respectively length and height of street canyon). This Paper reports the development of a 3-dimensional model to study the effect of non-uniform wall surface temperature distribution on the pollution dispersion and flow pattern within the short street canyons (L/H<3). For this purpose, a computational fluid dynamics (CFD) model is developed to investigate these effects on pollution dispersion in various prevailing wind velocities and directions. Moreover, active and passive techniques to reduce the level of concentration are examined. The study clearly shows that thermal-induced flow dominates during fair-weather condition.     

浅论滨水地区城市设计

简述了世界范围内的滨水区的发展历程、建设的经验以及滨水区景观开发的需要和可能性,从城市设计的角度入手,在滨水区城市形态研究的基础上,针对目前我国及国外滨水区开发现状,提出一些解决问题的方法和思路,对于指导滨水地区和整个城市的建设具有重要意义。     

A regression-based method for mapping traffic-related air pollution: application and testing in four contrasting urban environments

Accurate, high-resolution maps of traffic-related air pollution are needed both as a basis for assessing exposures as part of epidemiological studies, and to inform urban air-quality policy and traffic management. This paper assesses the use of a GIS-based, regression mapping technique to model spatial patterns of traffic-related air pollution. The model--developed using data from 80 passive sampler sites in Huddersfield, as part of the SAVIAH (Small Area Variations in Air Quality and Health) project--uses data on traffic flows and land cover in the 300-m buffer zone around each site, and altitude of the site, as predictors of NO2 concentrations. It was tested here by application in four urban areas in the UK: Huddersfield (for the year following that used for initial model development), Sheffield, Northampton, and part of London. In each case, a GIS was built in ArcInfo, integrating relevant data on road traffic, urban land use and topography. Monitoring of NO2 was undertaken using replicate passive samplers (in London, data were obtained from surveys carried out as part of the London network). In Huddersfield, Sheffield and Northampton, the model was first calibrated by comparing modelled results with monitored NO2 concentrations at 10 randomly selected sites; the calibrated model was then validated against data from a further 10-28 sites. In London, where data for only 11 sites were available, validation was not undertaken. Results showed that the model performed well in all cases. After local calibration, the model gave estimates of mean annual NO2 concentrations within a factor of 1.5 of the actual mean (approx. 70-90%) of the time and within a factor of 2 between 70 and 100% of the time. r2 values between modelled and observed concentrations are in the range of 0.58-0.76. These results are comparable to those achieved by more sophisticated dispersion models. The model also has several advantages over dispersion modelling. It is able, for example, to provide high-resolution maps across a whole urban area without the need to interpolate between receptor points. It also offers substantially reduced costs and processing times compared to formal dispersion modelling. It is concluded that the model might thus be used as a means of mapping long-term air pollution concentrations either in support of local authority air-quality management strategies, or in epidemiological studies.     

Assessment of drainage infrastructure for urban areas

This paper discusses various factors that should be considered in assessing the effectiveness of an urban drainage system, based on studies on such systems in the Midwestern United States. Important factors to be taken into account in analysing a drainage system include: the physical condition of the system; the competency of the data on the sizes, elevations, and locations of the drainage components; the current and future tributary areas and land cover; the outfall/outlet conditions; the inlet conditions; and local climatological data.     

Monitoring Pt and Rh in urban aerosols from Buenos Aires, Argentina

Vehicular traffic is the main source of platinum group elements (PGEs) in highly populated urban areas like Buenos Aires where a traffic density of 1,500,000 vehicles day(-1) (corresponding to 7,500 vehicles km(-2)) is estimated. Since there is no information on the levels of PGEs in Buenos Aires, a pilot study was undertaken to ascertain the amount of two major PGEs, namely Pt and Rh, in the atmosphere of this city. To this end, 49 samples of PM-10 particulate matter were collected during 7 days in seven representative sampling sites located downtown Buenos Aires and spread over an area of about 30 km(2). The collection of particulate matter was performed on ash-free glass-fiber filters using high volume samplers with PM-10 sampling heads. Filters loaded with the particulate matter were subjected to microwave (MW)-assisted acid digestion using a combination of HNO(3), HF and HClO(4). The resulting solutions were evaporated and then diluted with 0.1 mol l(-1) HCl. Analyses were performed by sector field inductively coupled plasma-mass spectrometry (SF-ICP-MS) and special attention was paid to the control of mass interferences. Statistical analysis was performed on the experimental data obtained for the element concentrations taking also into account local meteorological data for the monitored period. The highest concentrations of Pt and Rh were detected at two sites (Hospital Alemán and Casa Rapallini) located in streets with traffic consisting mostly of passenger cars. The Pt content (in pg m(-3)) in airborne particulate matter was found to vary from 2.3 to 47.7, with a mean value of 12.9+/-7, and that of Rh from 0.3 to 16.8, with a mean value of 3.9+/-2.8. These concentrations are by far below the levels for which adverse health effects might be expected to occur, i.e., around 100 ng m(-3). On the other hand, monitoring of PGEs should be carried out in a systematic fashion to detect possible dramatic increases from today's levels.     

Modelling population changes in small English urban areas

The authors examine processes underlying the growth of small urban areas in England. "There is evidence of 'people-led' growth in environmentally attractive locations (for example, through retirement migration). However, growth of small- and medium-sized towns also reflects employment decentralisation and deconcentration to freestanding or satellite towns, and the extension of commuter hinterlands.... Government policies encouraging growth are also demonstrated to be significant." The processes resulting in population decline in some small towns are identified. "The impact on modelling growth in urban areas of a diversity of causal processes and locational contexts for growth is considered."     

城市建筑色彩与形象的个性定位

当前,建筑色彩与城市形象已成为热门话题。一座城市、一幢建筑物,对其个性特色的追求是一个永恒的目标,而一个城市形象的好坏与否,则取决于建筑色彩的艺术感。城市中的公共建筑、住宅建筑色彩要具有地方特色,要协调一致,合理搭配。从某种意义上说,城市建设不应仅仅是经济繁荣的表象,更应成为人类文明与进步的艺术代言人。     

城市灾害中的急智变通

在城市生活事件中存在大量的应激源,即那些能引起全身性适应综合征或局部性适应综合征的灾害因素,它们为急智提供了特别情境。例如,有些事件的发生并非初始所料,却鬼斧神工地提供了成功的楔机;有些事情眼看谬误或败局己定,却又电闪雷鸣,形势急转;还有些为常人忽视的细枝末节,突然成为大决策的重要开端或依据……这些事件有三