数据的规模越来越大,要求数据挖掘算法有很高的执行效率.基于密度的聚类是聚类分析中的一种,其主要优点是发现任意形状的聚类和对噪音数据不敏感.提出了一种新的基于参考点和密度的CURD(clustering using references and density)聚类算...数据的规模越来越大,要求数据挖掘算法有很高的执行效率.基于密度的聚类是聚类分析中的一种,其主要优点是发现任意形状的聚类和对噪音数据不敏感.提出了一种新的基于参考点和密度的CURD(clustering using references and density)聚类算法,其创新点在于,通过参考点来准确地反映数据的空间几何特征,然后基于参考点对数据进行分析处理.CURD算法保持了基于密度的聚类算法的上述优点,而且CURD算法具有近似线性的时间复杂性,因此CURD算法适合对大规模数据的挖掘.理论分析和实验结果也证明了CURD算法具有处 理任意形状的聚类、对噪音数据不敏感的特点,并且其执行效率明显高于传统的基于R*-树的DBSCAN算法.展开更多
Living Library活动起源于欧洲,是近年来国外图书馆界采用的一种全新的读者服务方式。它通过借阅"活人"的方式减少偏见,促进理解和宽容,活动一经推出就受到读者的热烈欢迎。这种全新的服务方式更新了图书馆服务理念,拓展了图...Living Library活动起源于欧洲,是近年来国外图书馆界采用的一种全新的读者服务方式。它通过借阅"活人"的方式减少偏见,促进理解和宽容,活动一经推出就受到读者的热烈欢迎。这种全新的服务方式更新了图书馆服务理念,拓展了图书馆读者服务模式,对图书馆在网络环境下的发展极具实践意义。在国内目前该项活动仍处于起步阶段,实现本地化和特色化尚需时日。展开更多
Purpose To establish and propose a national body mass index （BMI） reference for screening overweight and obesity in Chinese school-age children and adolescents. Methods 2000 CNSSCH （Chinese National Survey on Stude...Purpose To establish and propose a national body mass index （BMI） reference for screening overweight and obesity in Chinese school-age children and adolescents. Methods 2000 CNSSCH （Chinese National Survey on Students Constitution and Health） data, including 216 620 primary and secondary school students aged 7 to 18 years old, were used as a reference population. Compared with those of the NCHS intematioanl reference, three temporary sets of cut-off BMI were proposed by testing different combinations of P85, P90, and P95. When physiological and biochemical measures between and among “obesity” “overweight”, and “normal weight” groups were taken into consideration, set Ⅱ was selected to be the most appropriate one. The sex-age-specific curves were then plotted and smoothed by using B-spline method. Results Based on the samples from costal developed metropolis, the BMI curves successfully overcame the shortcomings of lower and level-off tendency of the Chinese total population. Temporary set H, composed by cut-offs of P85 for overweight and P95 for obesity, was finally selected by its sensitivity and peculiarity. BMI 24 and 28 were used as cut-offs for overweight and obesity for both males and females aged 18 years old. These cut-offs, consistent with Chinese Adult＇s Reference, was proposed as the Body mass index reference for screening overweight and obesity in Chinese school-age children and adolescents. Conehlsion The new reference clearly showed its superiorty in both prospectivity and actuality. The proposed reference minimized the gaps of the BMI curve between Chinese adolescents and the international reference. Most importantly was that it was consistent with the Eastern Asia ethnic characteristics of body fatness growth. It was therefore proposed by the Working Group on Obesity in China （WGOC） to use it as an nationwide reference for screening overweight and obesity of school-age children and adolescents in China.展开更多
文摘数据的规模越来越大,要求数据挖掘算法有很高的执行效率.基于密度的聚类是聚类分析中的一种,其主要优点是发现任意形状的聚类和对噪音数据不敏感.提出了一种新的基于参考点和密度的CURD(clustering using references and density)聚类算法,其创新点在于,通过参考点来准确地反映数据的空间几何特征,然后基于参考点对数据进行分析处理.CURD算法保持了基于密度的聚类算法的上述优点,而且CURD算法具有近似线性的时间复杂性,因此CURD算法适合对大规模数据的挖掘.理论分析和实验结果也证明了CURD算法具有处 理任意形状的聚类、对噪音数据不敏感的特点,并且其执行效率明显高于传统的基于R*-树的DBSCAN算法.
基金Funded by International Life Sciences Institute, Focal Point in China.
文摘Purpose To establish and propose a national body mass index （BMI） reference for screening overweight and obesity in Chinese school-age children and adolescents. Methods 2000 CNSSCH （Chinese National Survey on Students Constitution and Health） data, including 216 620 primary and secondary school students aged 7 to 18 years old, were used as a reference population. Compared with those of the NCHS intematioanl reference, three temporary sets of cut-off BMI were proposed by testing different combinations of P85, P90, and P95. When physiological and biochemical measures between and among “obesity” “overweight”, and “normal weight” groups were taken into consideration, set Ⅱ was selected to be the most appropriate one. The sex-age-specific curves were then plotted and smoothed by using B-spline method. Results Based on the samples from costal developed metropolis, the BMI curves successfully overcame the shortcomings of lower and level-off tendency of the Chinese total population. Temporary set H, composed by cut-offs of P85 for overweight and P95 for obesity, was finally selected by its sensitivity and peculiarity. BMI 24 and 28 were used as cut-offs for overweight and obesity for both males and females aged 18 years old. These cut-offs, consistent with Chinese Adult＇s Reference, was proposed as the Body mass index reference for screening overweight and obesity in Chinese school-age children and adolescents. Conehlsion The new reference clearly showed its superiorty in both prospectivity and actuality. The proposed reference minimized the gaps of the BMI curve between Chinese adolescents and the international reference. Most importantly was that it was consistent with the Eastern Asia ethnic characteristics of body fatness growth. It was therefore proposed by the Working Group on Obesity in China （WGOC） to use it as an nationwide reference for screening overweight and obesity of school-age children and adolescents in China.
