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This work studies the image segmentation algorithm in passive THz imaging. Considering the feature that the passive THz image has different smoothness in horizontal and vertical direction, an improved Laplacian of Gaussian (LOG) operator is proposed to rectify the different smoothness in directions. Different from the traditional LoG operator with its isotropy, the improved operator has different edge test scales in horizontal and vertical direction. Experiments show that, with the use of improved operator, human's body and the concealed object in THz images could be automatically segmented. The concealed objects could be identified directly and efficiently that satisfies the application requirements of passive THz image. [ABSTRACT FROM AUTHOR]

The degrading regulations of combined pollutants of chlorfenvinfos and fenthion in red soil were studied, in which soil incubation, gas chromatography with nitrogen-phosphorus detection for analysis are utilized. The main conclusions drawn are as follows: under combined pollution condition, the degrading amount of fenthion was significantly higher than that of fenthion alone in soil; under saturated soil humidity, the degrading amount of fenthion was less changed, while that of chlorfenvinfos was increased by 33.3% - 1250%. Soil drought made degradation amount of fenthion decreased a little, while made chlorfenvinfos increased significantly prior to the 21st day after addition of pesticide; nitrogen fertilizer application stimulated both fenthion and chlorfenvinfos degraded; the chemical degrading amount of fenthion in soil with organic matter eliminated was decreased by 22.4% - 30.8%, while that of chlorfenvinfos was increased 42.1% - 2370% at the earlier stage, and was decreased 11% - 17.3% at the later stage. Therefore, there are differences of degrading regulation between single pesticide pollutant and combined pesticide pollutants in soil, and the degradation of organophosphorus pesticides in combined pollutants are influenced with each other.