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排序方式: 共有412条查询结果,搜索用时 31 毫秒
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First flush of storm runoff pollution from an urban catchment in China 总被引:13,自引:0,他引:13
Storm runoff pollution process was investigated in an urban catchment with an area of 1.3 km^2 in Wuhan City of China. The results indicate that the pollutant concentration peaks preceded the flow peaks in all of 8 monitored storm events. The intervals between pollution peak and flow peak were shorter in the rain events with higher intensity in the initial period than those with lower intensity. The fractions of pollution load transported by the first 30% of runoff volume (FF30) were 52.2%-72.1% for total suspended solids (TSS), 53.0%-65.3% for chemical oxygen demand (COD), 40.4%-50.6% for total nitrogen (TN), and 45.8%-63.2% for total phosphorus (TP), respectively. Runoff pollution was positively related to non-raining days before the rainfall. Intercepting the first 30% of runoff volume can remove 62.4% of TSS load, 59.4% of COD load, 46.8% of TN load, and 54.1% of TP load, respectively, according to all the storm events. It is suggested that controlling the first flush is a critical measure in reduction of urban stormwater pollution. 相似文献
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Y.K. Pu F. Jia S.F. Wang T. Skjold 《Journal of Loss Prevention in the Process Industries》2007,20(4-6):462-469
The reactivity of a combustible dust cloud is traditionally characterized by the so-called KSt value, defined as the maximum rate of pressure rise measured in constant volume explosion vessels, multiplied with the cube root of the vessel volume. The present paper explores the use of an alternative parameter, called the maximum effective burning velocity (ueff,max), which also is derived from pressure–time histories obtained in constant volume explosion experiments. The proposed parameter describes the reactivity of fuel–air mixtures as a function of the dispersion-induced turbulence intensity. Procedures for estimating ueff,max from tests in both spherical and cylindrical explosion vessels are outlined, and examples of calculated values for various fuel–air mixtures in closed vessels of different sizes and shapes are presented. Tested fuels include a mixture of 7.5% methane in air, and suspensions of 500 g/m3 cornstarch in air and 500 g/m3 coal dust in air. Three different test vessels have been used: a 20-l spherical vessel and two cylindrical vessels, 7 and 22 l. The results show that the estimated maximum effective burning velocities are less apparatus dependent than the corresponding KSt values. 相似文献
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Zekai Sen Abdulaziz Abo Saud Abdüsselam Altunkaynak Mehmet
zger 《Journal of the American Water Resources Association》2003,39(5):1209-1215
ABSTRACT: The quality of ground water in any aquifer takes its final form due to natural mixture of waters, which may originate from different sources. Water quality varies from one aquifer to another and even within the same aquifer itself. Different ground water quality is obtained from wells and is mixed in a common reservoir prior to any consumption. This artificial mixing enables an increase in available ground water of a desired quality for agricultural or residential purposes. The question remains as to what proportions of water from different wells should be mixed together to achieve a desired water quality for this artificial mixture. Two sets of laboratory experiments were carried out, namely, the addition of saline water to a fixed volume of fresh water. After each addition, the mixture volume and the electric conductivity value of the artificially mixed water were recorded. The experiments were carried out under the same laboratory temperature of 20°C. A standard curve was developed first experimentally and then confirmed theoretically. This curve is useful in determining either the volume or discharge ratio from two wells to achieve a predetermined electrical conductivity value of the artificial mixture. The application of the curve is given for two wells within the Quaternary deposits in the western part of the Kingdom of Saudi Arabia. 相似文献
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压入式局部通风工作面风流分布数值模拟研究 总被引:7,自引:1,他引:6
笔者应用三维k -ε紊流模型描述压入式局部通风工作面风流的流动过程 ,并采用控制容积法导出了描述流体流动方程的离散化方程式 ;用计算流体力学的方法求得了三维k -ε紊流模型的数值解。采用SIMPLE(压力耦合方程式的半阴解法 )算法解算流场 ;TDMA(三对角线算法 )和Gauss Seidel法结合通过线顺法求解离散方程。利用弱松弛法防止非线性方程组迭代求解过程中的发散现象 ,获得了掘进工作面空间的速度分布 ;并将模拟解算结果与在具有实际尺寸的拱形巷道模型中测得的实验结果进行了对比。数值计算结果与模型实验测定结果非常一致 ,验证了笔者的数学模型和数值模拟方法的正确性。 相似文献