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71.
有机硅在绝缘子防污闪方面的应用 总被引：12，自引：0，他引：12
简述了硅油、硅脂、室温硫化硅橡胶、高温硫化硅橡胶、硅树脂等有机硅材料在绝缘子防污闪方面的应用 相似文献
72.
Andrés H. Fernández-Barrera Daniel Castro-Fresno Jorge Rodríguez-Hernández Miguel A. Calzada-Pérez 《Canadian Metallurgical Quarterly》2008,134(5):659-665
This paper presents the Cantabrian portable infiltrometer (CP infiltrometer), a specially designed device based on rainfall simulation for the assessment of the infiltration capacity of all types of urban pavements. Several pervious and impervious surfaces were tested with the LCS permeameter, an existing infiltration test based on the use of a column of water, and the CP Infiltrometer, simulating rain intensities with return periods of 10, 50, and 500 years and 5?min duration. The discussion of the results indicates that the CP infiltrometer could be used successfully to identify different levels of infiltration capacity and to assess the correct performance of pervious surfaces on which design, construction, and maintenance decisions are based. 相似文献
73.
Samples of sediment found on an urban road in Aberdeen (Scotland) were collected by washing designated surfaces. This method, called the “wet” method, was capable of collecting sediment of the smallest particle size range that is normally left behind by traditional sampling techniques using dry vacuuming. Over 17 months (mainly on a weekly basis), 66 samples were collected and analyzed for sediment loading, particle size distribution, concentration of heavy metals (Zn, Cu, Pb, Cd) in four sediment size fractions, and several dissolved pollutants in the effluent collected from washing (NO3?,?SO42?,?PO43?,?Cl?,?F?,?NH4+, total organic carbon, total carbon). Standard statistical methods, including multiple regressions, were used to determine relationships amongst different sediment characteristics. It was found that sediment loading, as well as concentrations of Cl? and SO42?, were highest in the winter months, especially when snow was present on the road surface. It was observed that 66% of total road sediment loading was found within a 0.5 m strip next to the curb. The average sediment particle sizes found were smaller than those previously recorded in the literature. As expected, the concentrations of heavy metals were highest in the smallest particle size fraction analyzed (<63?μm), and this occurred during the summer months when less sediment was available on the street surface. The antecedent dry weather period had a very weak and negative influence on the loading rate of the smallest particle size fraction next to the curb. 相似文献
74.
75.
论城市滨水区的可持续性城市设计 总被引：30，自引：0，他引：30
目前城市滨水区已农斩成为各国城市开发的热点,为保证了滨水区的空间环境品质,在开发中必须引入城市设计观念与方法。试以可持续观点,从生态、经济、技术四方面探讨城市滨水区的可持续性城市设计,以期对当前水区的开发建设起一定的指导作用。 相似文献
76.
粉煤灰在砂浆中的应用 总被引：1，自引：0，他引：1
砂浆是建筑工程中用途较广的材料,粉煤灰是工业大宗废渣之一。粉煤灰取代砂浆中的部分砂,水泥,石灰膏,或者粉煤灰作为掺和料直接用于砂浆中,能改善砂浆的和易性及其它性能,节约原材料,利用粉煤灰,降低砂浆成本,减少环境污染,既有经济价值。又人社会效益。 相似文献
77.
城市中的绿色通道及其功能 总被引：15，自引：0，他引：15
本文主要介绍绿色通道的概念、发展阶段及在城市建设中的作用;简述国外绿色通道规划的案例研究并讨论它在中国发展面临的困难。 相似文献
78.
Ali A.Z. DouAbul Jamal K. Abaychi Manal K. Al-Asadi Haytham Al-Awadi 《Water research》1987,21(8):955-960
In view of the desire to improve the water quality of the heavily polluted branches of the Shatt al-Arab River at the City of Basrah, it was proposed to maintain effective flushing as well as contracting sewerage system. The present study was conducted in order to examine the water quality of these branches in an attempt to evaluate the effectiveness of the proposed flushing system. It has been found that their waters contained very low levels of dissolved oxygen and relatively high amounts of both COD and BOD5. The annual average water quality parameters for Basrah Branches were: dissolved oxygen 3.4 ppm; pH 7.67; hydrogen sulphide 1.4 ppm; ammonia 97 μg-at. N l−1; COD 15.9 mg l−1; BOD5 12.7 mg l−1; dissolved silicates 202 μg-at. Si l−1; dissolved reactive phosphate 13.4 μg-at. P-PO43− l−1; nitrate 10.4 μg-at. N-NO3− l−1; nitrite 2.1 μg-at. N-NO2− l−1 and chlorophyll-α 14.3 mg m−3. Based on our calculations, it has been concluded that the proposed system is effective, thus within a flushing cycle all of the above mentioned parameters will become within the acceptable values of the Shatt al-Arab water quality. Moreover, this system has no appreciable effect upon the water quality characteristics of the Shatt al-Arab River due to the fact that it discharges a high volume of water annually. However, It has been recommended to dredge the deposited sludge to a minimum depth of 50 cm. 相似文献
79.
Benthic diatom assemblages have been used to evaluate the water quality of two rivers subjected to marked human influences. These rivers, the Llobregat and the Ter, are located in N.E. Spain, and supply water for industrial, agricultural and urban requirements of roughly three million people. The diatom communities in the headwaters are similar in both rivers (Achnanthes minutissima, Cymbella ventricosa, Gomphonema anguslatum). Species of Navicula, Nitzschia and Gomphonema develop in the middle reaches of both rivers when not disrupted by extraneous factors. In the river Ter significant pollution modifies this community and Nitzschia palea, Nitzschia gandersheimiensis and Gomphonema parvulum appear as the most tolerant species. In the Llobregat, the pollution from the salt mine operations also modifies the diatom assemblage and Nitzschia frustulum, Surirella ovata, Navicula atomus are the most abundant species. Reservoirs in the river Ter improve the quality of water and a community of Fragilaria sp. pl. becomes dominant downstream. 相似文献
80.
The degree of organic pollution in natural waters of northern Greece has been evaluated through measurement of TOC, DO, fluorescence, absorbance and complexing capacity. Additionally certain other parameters were measured like temperature, conductance, hardness, alkalinity and total iron content to get a better idea of the extent of pollution. The results showed that Lake Agios Vasilios was the most heavily polluted. On the other hand the River Loudias has greater organic charge than the River Axios. 相似文献