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91.
对目前使用较为常见的pH预测模式和方法进行了分析探讨,提出了各自的适用和范围和存在问题,并提出了比较合理的pH值预测模式和方法. 相似文献
92.
通过用重量法测定水中油类物质的几个影响因素的研究,得出了能够取得满意测定结果的方法.改进后的方法,减轻了工作量,节省了分析费用,有利于批量分析. 相似文献
93.
本文根据前文所提联合上限法和主应力法确定模具表面压力分布的基础原理,计算了圆柱坯料正挤压和十字头锻件镦挤时模具表面的压力分布,所得结果与测定值很吻合,进一步证明了UBM/SM法实际应用的可靠性. 相似文献
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The investigation of object-by-attribute matrices is very common in statistics and data analysis with the aim of uncovering every possible relationship among objects and/or attributes. Formal Concept Analysis (FCA) is a method, which stems directly from partial order and lattice theory, which provides an efficient tool to symmetrically uncover linkages among objects and attributes whenever a relation stands among the two sets. It provides efficacious graphical representation and computes association rules between attributes, thus helping in the detection of possible synergism or antagonism of attributes. In this paper, FCA potentialities are discussed and described by means of a case study already investigated by other partial order techniques: the case of Lake Ontario sediment samples. Data derive from a ‘test battery’ for a simultaneous analysis of degradation of Lake Ontario samples, which are basically of two typologies: hygienic and toxicity tests. A multi-valued approach is adopted to cope with the ordinal feature of data. Results highlight interesting interaction among hygienic compounds and a synergism between the two toxicity tests. 相似文献
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A field study was established to investigate the chemical composition of atmospheric aerosols in Chicago, IL. One goal of
this study was to determine the influence of precursor trace gases and local meteorology on concentrations of secondary aerosol
ionic species. This paper describes the method details, shows the method is analytically valid, and reports overall as well
as some specific results found during the field study. Two particulate air samples were collected per day onto quartz fiber
filters at the Loyola University Chicago Air Station during the summer months in 2002–2004. In parallel, mixing ratios of
ozone and nitrogen oxides were monitored and weather parameters were recorded. Particulates were extracted from the filter
substrates and the subsequent solutions were analyzed by ion chromatography for anions, including low molecular weight organic
acids, and cations. A washing procedure was implemented to reduce the high background values of the quartz fiber filters.
Method validation showed that the collection method was efficient for all ions with exception of nitrate, whose efficiency
of 70% indicated losses caused by volatilization. The extraction method also proved efficient for both field and laboratory
samples, and the repeatability of the method was high with relative standard deviations less than 10% for all ions. Reproducibility
of the results was determined by comparison of sulfate to sulfur analyzed by total reflection X-ray fluorescence spectrometry
and proved to be high as well. Concentrations differed significantly between the three summer studies due to varying levels
of precursor species as a consequence of distinct temperatures and wind direction profiles. 相似文献