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691.
应用人工神经网络方法对海水入侵危害程度划区分类 总被引:5,自引:0,他引:5
本文将目前信息处理系统中最有效的人工神经网络方法,应用于海水入侵地区,对其危害程度进行划区分类,提出了解题原理,步骤和计算方法,丰富了对海水入侵现象的研究手段。在莱州市滨海地区的计算表明,该方法是可行的。 相似文献
692.
James W. Warner David Molden Mondher Chehata Daniel K Sunada 《Journal of the American Water Resources Association》1989,25(2):401-411
ABSTRACT: One of the most common methods of artificial recharge to the ground water is from basins. In this paper, seven analytical solutions that describe artificial recharge from basins are presented. Most of these solutions are derived by directly solving the general partial differential equation for ground water flow. The solutions differ in that they use different boundary conditions, basin shapes, and consider the nonlinearity of the artificial recharge problem differently. Use of each analytical solution is demonstrated in this paper by application to an example problem. A comparison of each analytical solution presented in this paper was made to give suggestions on their use, their ease of implementation, and their relative agreement. Although no attempt is made in the paper to conclude which analytical solution is best for all problems, some general conclusions can be stated on the applicability of the various analytical solutions. Of the analytical solutions presented in this paper, Glovers and Hantush's solutions for rectangular recharge basins are highly recommended. Baumanns solution for a circular basin also gave fairly reliable results and is very easy to evaluate numerically. 相似文献
693.
M. Hossein Sabet Otto J. Helweg 《Journal of the American Water Resources Association》1989,25(5):1047-1053
ABSTRACT: Construction of a “peaking storage tank” may reduce the operational cost of municipal water in the availability of a time-of-use energy rate. A peaking storage tank is used for storing water that is pumped from wells or other sources of supply during off-peak periods when energy costs are less for use during periods of on-peak water demand. The optimal size of a peaking storage tank is that which results in the minimum total cost, which includes both the storage construction cost and the cost of operation of the pumps. The operational cost for a given time-of-use rate is determined by help of a pipe network simulation model solved by the Newton-Raphson technique and a dynamic programming optimization model. A more simplified method is also introduced. Analyses show that low off-peak energy costs make the construction of peaking storage tanks economically attractive and reduce on-peak energy use, which results in electrical load leveling. 相似文献
694.
John W. Labadie Dennis A. Bode Andrew M. Pineda 《Journal of the American Water Resources Association》1986,22(6):927-940
ABSTRACT: A water supply network optimization model called MODSIM3 is presented as a decision-support tool for aiding city staff in determining how best to utilize and exchange existing and potential water supplies with other users in a river basin. The model is applied to the City of Fort Collins, Colorado, water supply system as a means of determining optimum ways the City can utilize direct flow rights, storage rights, and exchangeable waters from various sources. Results clearly confirm both the benefits of the use of exchanges and the value of MODSIM3 as a water supply planning and management tool. 相似文献
695.
Henry L. Garie Alan McIntosh 《Journal of the American Water Resources Association》1986,22(3):447-455
ABSTRACT: A study of benthic macroinvertebrate community composition was conducted at eight sites along Shabakunk Creek, a small stream in Mercer County, New Jersey, which receives urban runoff. The relationship between changes in substrate composition and the nature of the benthic macroinvertebrate community has been examined. Organisms were collected seasonally from natural substrates in riffles. Attempts to employ artificial substrates for invertebrate collection proved unsuccessful, as the population on the samplers was not representative of that in the stream bed. Number of total benthic macroinvertebrate taxa collected declined from 13 in relatively undeveloped upstream areas to four below heavily developed areas, while population density decreased simultaneously in the same areas. Periphyton samples collected from natural substrates were analyzed for selected heavy metals. Significantly higher heavy metal concentrations are reported from substrates sampled below heavily developed areas, and changes in these values are discussed with regard to changes in benthic macroinvertebrate distribution. 相似文献
696.
Rusidan Lubis Michael V. Martin B. Starr McMullen 《Journal of the American Water Resources Association》1987,23(4):673-680
ABSTRACT: Grain transportation is a major economic activity on the multiple use Snake-Columbia River System. Congress is currently considering increased transportation user fees aimed at recapturing federal expenditures for waterway operations and maintenance. Three types of fee structure and four levels of cost recovery are evaluated using a network program model. In each case traffic is diverted away from the river to other Puget Sound ports via truck and rail transport modes. Grain shippers in the region will be adversely affected by a higher transport bill. The Lower Columbia River port economic activities will be negatively affected; however, competitive uses of the river, recreation, and hydroelectric generation will likely benefit modestly. 相似文献
697.
698.
论述了组建三级环境监测网的必要性和重要性及在环境监测中的作用,组建三级环境监测网是环境监测工作不断拓展和深化发展的需要。 相似文献
699.
700.
交通事故发生规律与城市道路系统的规划设计研究 总被引:4,自引:1,他引:4
蔡军 《中国安全科学学报》2005,15(4):16-20
笔者分析了城市交通事故发生率与道路等级、道路断面形式、路网密度、交叉口形式、道路车速的关系及交通事故人群的分布规律,认为道路宽而稀、支路缺乏、街道功能不清是我国城市道路网与用地微观布局的基本特点。大量数据分析表明,这种路网体系与我国的城市交通事故率偏高有着密切关系。路网规划是城市路网建设的基本依据,笔者认为,应当将降低城市交通事故率作为路网规划的考虑内容之一,同时指出,应在路网规划中合理选择道路断面形式、交叉口形式,建议适度加密路网、健全支路体系、理清街道功能,并考虑城市道路的车速控制与驾驶心态调整。 相似文献