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31.
A geochemical baseline provides the means to distinguish between the pedogenic origin and the anthropogenic origin of the
trace element in the environmental compartments. We collected 271 soil samples representative of different parent rocks and
soil types from the whole territory of Hong Kong and analyzed the composition of clay mineralogy and the contents of 15 chemical
elements (Fe, Cd, As, etc.) for these samples. The baseline was predicted with the method of the normalization procedure combined
with the relative cumulative frequency curve. The result indicated that Fe was the best reference element for the normalization
procedure among the five potential reference elements (Fe, Al, Sc, Ti, and Mn), followed by Sc and Ti. A poor correlation
was found between Sc, Ti, and Cu. The predicted baseline was much lower than the A-value of the Dutch List used usually in screening the polluted soil of Hong Kong, implying that the extent of heavy metal
pollution might have been underestimated with respect to local lands. We also applied the cluster analysis to distinguish
the geochemical associations of the trace elements due to its importance to the baseline. Approximately three major associations
including the Fe–Mn-oxides related, Al oxides or Al-bearing-clay-mineralogy related and sulfide- related associations were
observed from the dendrogram. 相似文献
32.
在总结昭苏县25年雷达探测冰雹云和指挥防雹作业技术的基础上,研究并编写了昭苏县防雹雷达站防雹业务技术规程,本文扼要介绍雷达观测、雹云识别、作业指挥,效果分析等部分主要技术规程。 相似文献
33.
四平地区矿产资源以非金属为主,硅灰石、石灰石、硅砂、膨润土、伊利石、天然气等矿种储量位居吉林省同类矿种前列。本文通过对国内外非金属矿开发利用的调查研究,对本区非金属矿深加工及开发方向做了进一步探索,提出了可供政府决策的观点,只有做好非金属矿产深加工工作,四平矿业经济的跨越式发展才会有坚实的基础。 相似文献
34.
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36.
基于能力谱法的SSI体系抗震pushover分析方法 总被引:1,自引:0,他引:1
本文首先经过2次等效将土与结构相互作用的多自由度体系等效为单自由度体系,并给出了修正反应谱和等价能力谱的确定方法,进而提出了基于能力谱法考虑土与结构动力相互作用(SSI)效应的结构体系pushover分析方法(SSIPA);然后对3种不同高度考虑SSI效应的结构体系在5条地震动作用下采用本文提出的方法进行了算例分析,将结果与非线性时程分析的结果进行了比较,研究了本方法的适用性和准确性;最后,与建筑抗震设计规范的设计反应谱相结合,对9层考虑SSI效应的钢结构用本文提出的方法进行了弹塑性地震反应分析,根据我国抗震设计规范的规定进行抗震性能的评估验证了本方法的可行性。 相似文献
37.
文章介绍了瞬态瑞雷面波勘探技术的理论基础和勘探原理、工作方法、资料的整理与解释,并结合工程实例说明瞬态面波勘探技术的应用效果。 相似文献
38.
Catherine Rhein 《GeoJournal》1998,46(1):51-62
Which places are left to minorities in the housing and labour markets in metropolitan Paris? Over the last two decades, job structures have evolved dramatically, eroding the formerly prominent Paris working-class, shaking the social and political roots of its identity. These indicators would lead one to diagnose a growing fragmentation of metropolitan society. In the political debate, the burning issue of the crisis of suburbs has replaced outdated debate of the class struggle. This paper aims first to re-examine the interactions between social status and national origins, then analyses the housing conditions of different social strata, and finally demonstrates the pre-eminence of social status over national origins in the pattern of residential segregation. 相似文献
39.
Input determination has a great influence on the performance of artificial neural network (ANN) rainfall–runoff models. To improve the performance of ANN models, a systematic approach to the input determination for ANN models is proposed. In the proposed approach, the irrelevant inputs are removed. Then an adequate ANN model, which only includes highly relevant inputs, is constructed. Unlike the trial‐and‐error procedure, the proposed approach is more systematic and avoids unnecessary trials. To demonstrate the effectiveness of the proposed approach, an application to actual typhoon events is presented. The results show that the proposed ANN model, which is constructed by the proposed approach, has advantages over those obtained by the trial‐and‐error procedure. The proposed ANN model has a simpler architecture, needs less training time, and performs better. The proposed ANN model is recommended as an alternative to existing rainfall–runoff ANN models. Copyright © 2007 John Wiley & Sons, Ltd. 相似文献
40.
吴刚 《广东海洋大学学报》1990,(2)
在保证轴承安全而经济的运转条件下,轴承装配间隙取最小值,根据流体润滑理论,选择合适的润滑油;对于厚壁轴瓦,在磨合之后应调整到运转间隙。这样就可以充分利用轴承的使用寿命。 相似文献