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灰色局势决策-综合指数法对陕西段渭河水环境质量的评价研究 总被引:1,自引:0,他引:1
为了全面了解渭河干流(陕西段)的水环境质量情况,本文根据2000-2008年陕西段渭河干流13个水质监控断面的监测资料,选取COD、NH3-N、BOD5、DO4项主要污染物指标作为评价因子,采用灰色局势决策-综合指数方法对该河段的水环境质量进行综合评价。分析结果表明:①渭河干流陕西段综合水质指数介于1.967~5之间,表明该段河流已受到污染。自常兴桥断面直至潼关吊桥断面,COD、NH3-N、BOD5、DO的监测浓度仍然超过GB3838-2002地表水环境质量Ⅴ类标准限值要求,污染严重。②自2003年以来,渭河干流陕西段河流水体水质总体呈现好转趋势,主要表现在宝鸡市境内河段,这可能与入河污染物总量的变化相关。灰色局势决策-综合指数方法以细化的数值反映了评价结果,可进一步科学、客观地反映出渭河干流陕西段水质动态变化趋势。 相似文献
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《Advances in Engineering Software》2010,41(12):1266-1276
Modeling shot peening process is very complex as it involves the interaction of metallic surfaces with a large number of shots of very small diameter. Conventionally such problems are solved using the finite element software (such as ABAQUS) to predict the stresses and strains. However, the number of shots involved and the number of elements required in a real-life components for a 100% coverage that lasts a considerable duration of peening make such an approach impracticable. Ideally, a method that is suitable for obtaining residual compressive stresses (RCS) and the amount of plastic deformations with the least computational effort seems a dire need.In this paper, an attempt has been made to address this issue by using the discrete element method (DEM) in combination with the finite element method (FEM) to obtain reasonably accurate predictions of the residual stresses and plastic strains. In the proposed approach, the spatial information of force versus time from the DEM simulation is utilized in the FE Model to solve the shot peening problem as a transient problem. The results show that the RCS distribution obtained closely matches with that of the computationally intensive direct FEM simulation. It has also been established, in this paper, that this method works well even in the situations where the robust unit cell approaches are found to be difficult to handle. 相似文献
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