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281.
In the UK for the period 1994-99, a broad range of environmental projects were given financial support through the European Agriculture Guidance and Guarantee Fund under the Objective 1 and Objective 5b programmes. This paper is concerned with the ex-post evaluation of these projects set within a Sustainable Development framework. The aim was to identify project types or characteristics that offered the greatest return on investment. A classification of six broad project types was adopted. The evaluation revealed that there were significant differences between individual projects with respect to the type and scale, and temporal and social distribution of the benefits they delivered. In particular, as well as delivering environmental and economic benefits, many projects made a significant contribution to the development of human and social capital. The paper concludes that it is possible to improve the basis for future project selection in order to maximise the returns on environmental investments in the context of sustainable development. 相似文献
282.
在航空运输中 ,飞行安全最为重要 ,空管指挥是保证飞行安全的重要手段。地理信息系统 (GIS)能够将空间位置和性质属性结合在一起 ,非常适合空管指挥中直观性、安全性方面的需要。笔者在研究开发多功能空管系统的基础上 ,讨论了对地形、地物、航道、空管区、禁飞区等进行数字化的方法 ,提出了系统开发的主要技术 ,介绍了多功能空管系统的显示、控制、示警、辅助决策、智能纠错等功能 ,指出了空管系统的发展方向 相似文献
283.
284.
285.
Wang Xu Ma Yu Chen Hongwu Wen Gang Chen Shoujun Tao Zuyu Chung Yong-Seung 《Water, Air, & Soil Pollution: Focus》2003,3(2):67-79
With observational data spanning 1961–1999 from 90 meteorological stations in Xinjiang, China, the spatial and temporal characteristics of sandstorms and strong winds, and the contribution of strong winds to the occurrence of sandstormsare analyzed. Moreover, the dominant wind direction and minimumwind speeds during sandstorm periods are discussed. The research shows that although possessing similar climatic trends, sandstorms and strong winds in Xinjiang have opposite geographical distributions, i.e. places with more sandstorms show fewer strong winds. The contribution of strongwinds to sandstorms in northern Xinjiang is larger than that insouthern Xinjiang. The dominant wind directions clearly indicatethe paths of the weather systems that introduced the sandstorms.The minimum wind speeds in the sandstorms were over 10 ms-1in northern and eastern Xinjiang and in the Turpan and Yanqi Basins of southern Xinjiang. In Tarim Basin of southern Xinjiang,however, the minimum wind speed was about 6–8 ms-1, and even 6 ms-1 at its southern edge. 相似文献
286.
N. K. Woodfield J. W. S. Longhurst C. I. Beattie D. P. H. Laxen 《Journal of Environmental Planning and Management》2003,46(1):49-64
The UK National Air Quality Strategy has required local authorities to review and assess air quality in their area of jurisdiction and determine locations in their areas where concentrations of specific air quality pollutants are predicted to exceed national air quality objectives in the future. Statutory air quality management areas (AQMAs) are designated where air quality is predicted to be above specified objective concentrations by specific target dates, and statutory air quality action plans will be necessary to improve the local air quality within these areas. Over 124 local authorities in England (including London), Wales and Scotland anticipate declaring AQMAs following the conclusion of the statutory air quality review and assessment process. However, other influences are being exerted on the local air quality management process and AQMA decision-making processes. Such influences include regional and sub- regional collaborative working between local authorities and government agencies and wider political decision-making processes. Some regions of Great Britain (encompassing England (including London), Scotland and Wales) anticipate many AQMA designations, whilst other regions are not anticipating any such designations despite apparently similar air quality circumstances. Evidence for regional or sub-regional variations in the locations of anticipated AQMAs are examined through an evaluation of the outcomes of the scientific review and assessment process undertaken by local authorities declaring AQMAs, and through a local authority survey to identify influences on decision-making processes at a level above that of the local authority. Regional variation is reported in the type of pollutant causing AQMAs to be declared, in the numbers of AQMAs in regions and in the spatial distribution of AQMAs across Great Britain. 相似文献
287.
Sheng‐Feng Kuo Chen‐Wuing Liu Shih‐Kai Chen 《Journal of the American Water Resources Association》2003,39(1):59-73
ABSTRACT: This study presents three optimization techniques for on‐farm irrigation scheduling in irrigation project planning: namely the genetic algorithm, simulated annealing and iterative improvement methods. The three techniques are applied to planning a 394.6 ha irrigation project in the town of Delta, Utah, for optimizing economic profits, simulating water demand, and estimating the crop area percentages with specific water supply and planted area constraints. The comparative optimization results for the 394.6 ha irrigated project from the genetic algorithm, simulated annealing, and iterative improvement methods are as follows: (1) the seasonal maximum net benefits are $113,826, $111,494, and $105,444 per season, respectively; and (2) the seasonal water demands are 3.03*103 m3, 3.0*103 m3, and 2.92*103 m3 per season, respectively. This study also determined the most suitable four parameters of the genetic algorithm method for the Delta irrigated project to be: (1) the number of generations equals 800, (2) population size equals 50, (3) probability of crossover equals 0.6, and (4) probability of mutation equals 0.02. Meanwhile, the most suitable three parameters of simulated annealing method for the Delta irrigated project are: (1) initial temperature equals 1,000, (2) number of moves equal 90, and (3) cooling rate equals 0.95. 相似文献
288.
陈淑红 《中国环境管理干部学院学报》2003,13(1):20-22
本文通过对秦皇岛经济技术开发区居民小区生活污水进行处理并回用的可行性分析,得出城市生活污水经过适当处理后,完全可以再利用,从而达到节约水资源的目的,实现经济效益与环境效益的统一。 相似文献
289.
Demonstration of Line Transect Methodologies to Estimate Urban Gray Squirrel Density 总被引:2,自引:0,他引:2
Eric W. Hein 《Environmental management》1997,21(6):943-947
Sciurus carolinensis ) have been labor intensive and costly, I demonstrate the use of line transect surveys to estimate gray squirrel density and
determine the costs of conducting surveys to achieve precise estimates. Density estimates are based on four transects that
were surveyed five times from 30 June to 9 July 1994. Using the program DISTANCE, I estimated there were 4.7 (95% CI = 1.86–11.92)
gray squirrels/ha on the Clemson University campus. Eleven additional surveys would have decreased the percent coefficient
of variation from 30% to 20% and would have cost approximately $114. Estimating urban gray squirrel density using line transect
surveys is cost effective and can provide unbiased estimates of density, provided that none of the assumptions of distance
sampling theory are violated. 相似文献
290.
W. Richard Dubourg 《Natural resources forum》1997,21(3):191-200
Economic interpretations of sustainable development have concentrated on the need to maintain the aggregate capital stock intact, so as to ensure a constant stream of welfare through time. A sectoral approach to sustainability, in terms of this model, will be justified if substitution possibilities between that sector and the rest of the economy are limited. This assumption is examined in relation to the water sector, and it is found that further assumptions about substitution possibilities need to be made within the sector itself. Suggestions are offered as to how such substitutions might be made to advantage, which is contrasted to recent water management practices in England and Wales. It is argued that assumptions about substitution possibilities are in general overly restrictive, with the result that sustainability objectives fall short of optimum levels that could be achieved. 相似文献