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《Journal of computational and graphical statistics》2013,22(2):332-353
Spatial scan density (SSD) estimation via mixture models is an important problem in the field of spatial statistical analysis and has wide applications in image analysis. The “borrowed strength” density estimation (BSDE) method via mixture models enables one to estimate the local probability density function in a random field wherein potential similarities between the density functions for the subregions are exploited. This article proposes an efficient methods for SSD estimation by integrating the borrowed strength technique into the alternative EM framework which combines the statistical basis of the BSDE approach with the stability and improved convergence rate of the alternative EM methods. In addition, we propose adaptive SSD estimation methods that extend the aforementioned approach by eliminating the need to find the posterior probability of membership of the component densities afresh in each subregion. Simulation results and an application to the detection and identification of man-made regions of interest in an unmanned aerial vehicle imagery experiment show that the adaptive methods significantly outperform the BSDE method. Other applications include automatic target recognition, mammographic image analysis, and minefield detection. 相似文献
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Chun‐Yan An Xiao‐Ming Li Chun‐Shun Li Shu‐Shan Gao Zhuo Shang Bin‐Gui Wang 《Helvetica chimica acta》2013,96(4):682-687
Two new triazoles, chrysotriazoles A and B ( 1 and 2 , resp.), along with two known quinazolinones, 3 and 4 , two known 2‐(4‐hydroxyphenyl)acetamides, 5 and 6 , and two known N‐(4‐hydroxystyryl)formamides, 7 and 8 , were isolated and identified from the culture extract of Penicillium chrysogenum EN‐118, an endophytic fungus obtained from the marine brown alga Sargassum pallidium. The structures of the isolated compounds were elucidated by NMR‐spectroscopic analysis, and that of compound 1 was confirmed by X‐ray crystallographic analysis of its p‐bromobenzoate derivative. Compounds 4, 5 , and 7 showed moderate cytotoxicities against Du145, A‐549, and HeLa cell lines. 相似文献
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