Withering is the first step in the processing of congou black tea. With respect to the deficiency of traditional water content detection methods, a machine vision based NDT (Non Destructive Testing) method was established to detect the moisture content of withered leaves. First, according to the time sequences using computer visual system collected visible light images of tea leaf surfaces, and color and texture characteristics are extracted through the spatial changes of colors. Then quantitative prediction models for moisture content detection of withered tea leaves was established through linear PLS (Partial Least Squares) and non-linear SVM (Support Vector Machine). The results showed correlation coefficients higher than 0.8 between the water contents and green component mean value (G), lightness component mean value (L*) and uniformity (U), which means that the extracted characteristics have great potential to predict the water contents. The performance parameters as correlation coefficient of prediction set (Rp), root-mean-square error of prediction (RMSEP), and relative standard deviation (RPD) of the SVM prediction model are 0.9314, 0.0411 and 1.8004, respectively. The non-linear modeling method can better describe the quantitative analytical relations between the image and water content. With superior generalization and robustness, the method would provide a new train of thought and theoretical basis for the online water content monitoring technology of automated production of black tea.

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Isotopic ratios were used to identify the source of Lead (Pb) contamination in rural soils from Southeast China. Enrichment of Pb in surface soils was detected from three sampling locations, with the 206Pb/207Pb ratio indicating recent anthropogenic input. The 206Pb/207Pb ratio from deeper soil profiles reflected the ratio from parent basalt. Mass fractions of anthropogenic-derived Pb for soil samples in the upper profiles was as high as 50%, implying that surface soils in the current study were impacted by anthropogenic activity. The 206Pb/207Pb and 208Pb/206Pb ratios were similar to anthropogenic sources including the combustion of coal, which has been common practice in the region for 2500 years. Considering the relatively short history of petroleum use in this area and the rural location of soils, anthropogenic Pb source from coal burning was considered to be the main cause of lead pollution.

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