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1.
Krishan P. Singh 《Journal of the American Water Resources Association》1976,12(2):381-392
ABSTRACT. Unit hydrographs derived by using two methods, linear programming and least squares, are compared. Test data comprise rainfall and runoff information from four storms over the North Branch Potomac River near Cumberland, Maryland. The mathematical bases of these methods for unit-hydrograph derivation are explained. The linear programming method minimizes the sum of absolute deviations, and the least squares method minimizes the sum of the squares of deviations. Computer subroutines are readily available for application of these methods. The unit hydrographs derived with the two methods are practically the same for storms 2 and 3, but differ somewhat for storms 1 and 4. However, the reconstituted direct surface runoff hydrographs are similar to those observed with the exception of the hydrograph for storm 4 which had a relatively more non-uniform rainfall excess of a considerably larger duration. 相似文献
2.
Predicting future quantities of obsolete household appliances in Nanjing by a stock-based model 总被引:1,自引:0,他引:1
China has become one of the largest producers of obsolete household appliances (HAs) in the world. However, information on discarded HAs in China is deficient owing to the unavailability of reliable data. The estimation of future obsolete streams is a crucial issue for the establishment of efficient waste collection and recycling systems. The present study describes a prediction model to forecast future obsolete HAs on the basis of information of in-use stocks of HAs in households. The model was applied to a forecasting analysis of quantities of obsolete HAs from 2009 to 2050 in Nanjing, China. The results show that a total of about 76 million units (2.8 million tonnes) of obsolete HAs will be generated in Nanjing over the next 40 years. Discarded air conditioners, color TV sets, and personal computers will be the major contributors. The total discarded amount of major kinds of HAs will increase from nearly 1.0 million units in 2009 to a maximum of 2.1 million units in 2040, and then decrease slightly to 2.0 million units in 2050. Urban households will generate significantly more obsolete HAs (about 56 million units) than rural households, due to the difference in their HA possession levels. The results of this study should help the Nanjing municipality to develop the collection and recycling systems and facilities needed for the obsolete HAs generated in the future. From a methodological perspective, the stock-based model provides a suitable tool to predict the generation of discarded HAs in the future. 相似文献
3.
徐靖 《中国环境管理干部学院学报》2005,15(2):111-113
由于城市建设的不断加快,城建案卷成倍增加,传统的手工操作已不能适应档案文献增长的速度.随着现代化科学技术的发展,新的科学技术,如光盘技术、缩微技术、声像技术也在冲击着城建档案工作的领域,成为城建档案工作中不可缺少的组成部分.所有这一切,都对城建档案的管理提出了更高的要求.计算机是现代化科学技术发展的重要标志,正以它独特的高效率统占着各个领域.利用计算机管理档案是城建档案管理现代化的核心. 相似文献
4.
为了进行电脑相关肌肉骨骼疾病(Computer Related Musculoskeletal Disorders)的办公室工效学研究,需要研发更有效的电脑使用工效学评价方法。鉴于键盘和鼠标是电脑操作者最主要的输入工具,而且高重复性的操作动作会增加患肌肉骨骼疾病的风险,为了保护电脑操作者的职业健康,本研究研发一套键盘和鼠标使用的工效学评价方法并且使用该评价方法评价键盘和鼠标的使用以及使用过程中的人体疲劳。评价方法设计包括:"键盘鼠标使用统计软件"、"疲劳问卷系统软件"和数据处理和结果可视化。应用此评价方法对25个对象进行了8周的纵向观察与评价。键盘鼠标使用的评价结果能够准确反映评价对象操作键盘鼠标的实际情况;对疲劳程度的分析结果也与实验室研究结论一致,得到了理论支持,成功研发了一套创新、有效的电脑键盘和鼠标使用的工效学评价方法。 相似文献
5.
G. R. Smith 《国际发展与全球生态学杂志》2013,20(3):262-270
A 17-month research programme focused on development of an Education for Sustainability (EFS) Global Media Network at Ball State University Indiana was recently concluded. The study results include some surprising conclusions related to the contradictions between the benefits of education for global sustainability and the use of technology to facilitate that educational process in achieving a more sustainable world. This article provides an overview of the EFS Network research programme and a discussion of some of the key results and conclusions related to advantages and disadvantages of technology-based learning. The article then addresses the environmental impact of computer technology manufacturing, use, and after-use. Research findings are utilized to illustrate the ecological footprint of computer-based education. The article concludes with a discussion about achieving a balance between the need for global-to-local sustainable education and the environmental impact of technology use for sustainable education. 相似文献
6.
James R. Groves David W. Moody 《Journal of the American Water Resources Association》1992,28(3):615-621
ABSTRACT: This report presents the results of a survey of hydrology faculties of colleges and universities in the United States and Canada. Information is presented on topics covered in classes, allocation of class periods to individual topics, textbooks, prerequisites, computer use, and accreditation categories for hydrology courses offered by engineering departments. Hydrology courses generally require courses in fluid mechanics, mathematics, statistics, and computer science as prerequisites. Topics that receive the largest allocation of time in both introductory and advanced courses include rainfall-runoff relations, the hydrologic cycle, routing and open channel flow, and statistics. Advanced courses place greater emphasis on watershed models than do the introductory courses. Hydrology courses at both levels allocate the smallest amounts of time to snow hydrology ground-water hydrology, and “other topics.” Very few courses include field or experimental work. In a discipline where computer modeling is a major tool, this lack of field and data-collection experience may lead students to underestimate the uncertainties associated with data used to calibrate models and the modeling results themselves. Survey responses on hydrology courses taught in departments other than civil engineering were too few to permit detailed analysis. Most of these courses spend approximately two-thirds of available class time on the same topics as presented in engineering hydrology courses. The balance of class time is spent on topics that emphasize the specialized interest of the particular discipline, such as soil physics and soil moisture in agricultural engineering. 相似文献
7.
8.
John Cairns Kenneth W. Thompson J. David Landers Michael J. Mckee Albert C. Hendricks 《Journal of the American Water Resources Association》1980,16(3):421-427
ABSTRACT: Electronic modifications necessary to adapt an existing fish opercular movement monitor for use in salt water are described. Ten species of fresh and salt water fishes were tested for suitability as test organisms for future studies of pollutional effects. It was concluded that with proper tank design most species would provide useful data and that the system could be easily adapted for use in marine situations. 相似文献
9.
Bettinetti R Quadroni S Crosa G Harper D Dickie J Kyalo M Mavuti K Galassi S 《Ambio》2011,40(4):341-350
Dichlorodiphenyltrichloroethane (DDT) is still used in Africa for the indoor control of malaria and it may represent a potential
hazard for wildlife. The littoral sediments of two alkaline-saline lakes, Natron (Tanzania) and Bogoria (Kenya), in the Eastern
Rift Valley, supporting large populations of lesser flamingos (Phoeniconaias minor), were analysed for DDT residues. Physical–chemical analyses (temperature, conductivity, pH and dissolved oxygen) were also
performed on the water of the two lakes and in the tributaries of Lake Natron, to evaluate the influence of the environmental
variables on pollutant occurrence. At Lake Natron, around 1 km from the sediment collection sites, tree leaves of Acacia tortilis were also collected. The main metabolite found in all sediment samples was pp’DDE, whilst equal concentrations of pp’DDT
and pp’DDE were measured in acacia leaves. The levels of DDTs measured in the sediments were within 5.9–30.9 ng g−1 d.w., reaching the maximum value in a tributary of Lake Natron. On the whole, the contamination of Lake Natron and Lake Bogoria
basins seems to be quite moderate. Nevertheless, the pp’DDE/pp’DDT ratio equals 1 in the Acacia tortilis leaves, which makes one suppose that the input of the parent compound was rather recent and could have been from aerial transport
or dust from relatively close-by old pesticides storage sites. 相似文献
10.
This article reviews planning issues relating to “high‐tech” industry in Britain, and uses a case study of a manufacturer of micro‐computers in Oxford, England as a focus for a discussion. It concludes that town planning categories are not, in themselves, a constraint on high technology firms, and suggests that the provision of sites and premises by local authorities is a useful and undervalued task. 相似文献