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991.
Kastner-Klein Petra Fedorovich Evgeni Ketzel Matthias Berkowicz Ruwim Britter Rex 《Environmental Fluid Mechanics》2003,3(2):145-172
The paper addresses the problem of the parameterisation of traffic induced turbulent motion in urban dispersion models. Results from a variety of full-scale and wind-tunnel studies are analysed and interpreted within a modelling framework based on scaling considerations. The combined effects of traffic and wind induced dispersive motions are quantified for different traffic situations (variable traffic densities, vehicle velocities and vehicle types) and incorporated into the developed parameterisations. A new dispersive velocity scale is formulated and recommendations regarding its application in urban dispersion models are given. The necessity of accounting for traffic induced air motions in predictions of street-canyon pollution levels is demonstrated. Further research is needed to verify the empirical constants in the proposed parameterisations and to generalize the developed approach for a broader range of urban building configurations, meteorological conditions, and traffic situations. 相似文献
992.
防洪保护及污水资源化工程对滇池环境保护的适用研究 总被引:1,自引:0,他引:1
滇池外海与草海分隔后,通过合理的调控,水资源是平衡的,且增加出口可从隧洞分洪达40/S,满足20年一遇分洪要求;工程运行将使滇池水质有所改善,对局部水域水质将会有较大改善;出水排入沙河使其失去饮用水功能,水生态环境变劣,而对螳螂川影响不明显;二期工程(三个水库的建设)使排水得到利用,产生一定的综合效益。 相似文献
993.
Sociological edge effects: Spatial distribution of human impact in suburban forest fragments 总被引:4,自引:0,他引:4
Glenn R. Matlack 《Environmental management》1993,17(6):829-835
Suburban forest fragments often experience heavy recreational and waste disposal use, with considerable damage to the vegetation.
To suggest strategies for conservation of the forest flora, spatial distributions of human impact were described in 40 fragmentary
stands in northern New Castle County, Delaware. The distribution of human impact showed a significant bias to the forest edge,
with 95% of localized damage occurring in the first 82 m. Forms of impact related to lawn maintenance fell significantly closer
to the edge than impacts related to recreation and showed the strongest edge orientation. Edge distances of campsites, vandalized
trees, and firewood gathering were negatively correlated with distance to the nearest graded road, indicating the importance
of road access. Several forms of impact were also clustered near footpaths, although distance to paths was independent of
edge distance in all cases. In terms of penetration of the forest and severity of damage, human impact greatly exceeds natural
edge effects reported for this community. These findings suggest that damage may be minimized by limiting road access and
avoiding the creation of small forest fragments. 相似文献
994.
ABSTRACT: To manage the first flush of storm runoff in urbanized areas, a diversion box and detention basin system has been proposed for a new storm sewer system or for retrofitting an existing system. A software package for a personal computer has been developed to facilitate the analysis and design of the system. Hydrographs and pollutographs are generated at the inlet and outlet of the diversion box and the detention basin. The peak outflow and peak pollutant concentrations are compared with the allowable outflow and pollutant concentration for urban stormwater quantity and quality management. The model is developed for both analysis and design purposes. 相似文献
995.
996.
研究的目的是找到目前条件下切实可行、效果显著而又成本低廉的碳减排方法。通过整理和论证,从建材的低碳生产、建材的节约使用、建筑的低碳、交通的低碳、建筑垃圾的回收利用、城市碳汇等方面总结出了一些技术方面和管理方面的措施。同时也分析了我国的现状,指出了与世界先进水平的差距,以及需要改进的地方。 相似文献
997.
选取引江济太工程中长江来水进入太湖第一站的贡湖湾为研究对象,基于2011年11月~2013年8月在贡湖湾的逐月野外调查,同时以湖心水域为参考,探讨引江济太对湖体N2O通量的影响.结果表明,贡湖湾N2O排放通量要显著高于湖心排放量,其N2O通量均值分别为6.9,2.1μmol/(m2·d),但在非引水期间2个湖区的N2O通量无显著差异.贡湖湾和湖心N2O通量呈现明显的季节变化,且均与水温呈显著负相关关系,但因受外源来水的影响,贡湖湾N2O通量的温度依赖程度相对较低.另外,2个湖区的N2O通量还与营养盐等因素有关.总体上,外源引水提高了贡湖湾N2O排放通量,但考虑到湖泊N2O通量受到内部和外部因子的综合协同影响,外源引水对湖泊N2O通量的具体调控机理还需要进一步探讨. 相似文献
998.
平面交叉口交通冲突安全评价失效分析及改进方法研究 总被引:4,自引:0,他引:4
在对传统的交通冲突安全评价方法失效原因分析的基础上,提出了交叉口交通冲突安全评价的改进方法,该方法避免了与冲突无关的交通流影响评价结果的现象。与传统方法对交叉口整体评价不同,该方法对交叉口内部的各类交通冲突类型分别进行冲突分析,再运用欧几里德贴近度评价法对交叉口进行综合交通安全评价。该方法能准确地评价交叉口整体安全状况,能分析出交叉口内部的安全问题,是一种实用的城市道路平面交叉口交通安全评价方法。在我国部分城市的城市道路交叉口的交通冲突安全评价应用中取得了良好的效果。 相似文献
999.
Chen Hongfeng Li Fen Li Xiangling . School of Environment Natural Resources Renmin University of China Beijing China . School of Natural Resources Environment Hefei University of Technology Hefei Anhui China 《中国人口.资源与环境(英文版)》2007,5(2):41-48
As a megacity with thriving economy, Shanghai is experiencing rapid motorisation and confronted with traffic congestion problems despite its low car ownership. It is of value to look into the policies on emission control of motor vehicle and congestion reduction in such a city to explore how to reconcile mobility enhancement with the environment. Results of a dynamic simulation displayed time paths of emissions from motor vehicles in Shanghai over the period from 2000 to 2020. The simulation results showed that early policies on emission control of motor vehicle could bring about far-reaching effects on emission reduc- tion, and take advantage of available low-polluting technologies and technical innovation over time. Travel demand management would play an important role in curbing congestion and reducing motor vehicle pollution by calming down car ownership rise and deterring inefficient trips as well as reducing fuel waste caused by congestion. 相似文献
1000.
荆江分蓄洪区防洪基础信息演示系统的构建和运行 总被引:1,自引:0,他引:1
荆江分蓄洪区适时分蓄超过荆江河道安全泄量的洪水,确保荆江大堤、江汉平原和武汉三镇的安全,为长江防洪做出了贡献。为有效开展分洪管理防洪决策信息支持,构建了一套分蓄洪区的防洪基础地理信息演示系统。分析了以往构建系统中需求分析和信息组织的不足,较为详细地进行了需求分析,科学地进行数据组织及数据库设计,并在此基础上,采用原型法进行系统设计。最后利用控件Mapobjects,将GIS功能嵌入Visual Basic 6.0编制的应用程序中,实现用户需求的各种功能。系统整合了分蓄洪区基础地理数据、水利设施以及安全建设等数据,较好地反映了荆江分蓄洪区的现实特点和意义。系统的运行得到湖北省荆江分蓄洪区工程管理局的肯定。 相似文献