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基于KPCA的教育特征群集挖掘与分析
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作者 吴宇航 陈凤凤 +1 位作者 江玲 万磊 《无线互联科技》 2023年第23期131-135,共5页
文章针对混合教学数据的特征分析与分级问题,提出了一种基于核主成分分析(Kernel Principal Component Analysis,KPCA)的方法。文章融合传统教学数据和在线教育数据,形成完整的教育特征数据链;利用复杂网络的研究方法和理论模型,构建教... 文章针对混合教学数据的特征分析与分级问题,提出了一种基于核主成分分析(Kernel Principal Component Analysis,KPCA)的方法。文章融合传统教学数据和在线教育数据,形成完整的教育特征数据链;利用复杂网络的研究方法和理论模型,构建教育特征数据网络模型;采用非线性KPCA特征抽取算法提取出影响教育质量的群集特征;建立针对教育质量、学生级别进行综合评价的评价模型,并对学生进行分级,从而更好地提供个性化教育干预,提高教学质量。通过实验验证了该方法的有效性和优越性,表明该方法能够有效地提取混合教学数据的非线性特征,并能够实现混合教学数据的分级。 展开更多
关键词 混合教学 核主成分分析 复杂网络 群集特征 综合评价
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基于单键群方法的地震前兆时空群集特征研究
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作者 刘希强 周蕙兰 +1 位作者 王梅 王华林 《西北地震学报》 CSCD 北大核心 2001年第1期13-20,共8页
利用单键群分析方法 ,对 1 976年唐山和 1 989年大同地震前多学科前兆异常的时空群集特征进行了研究 .对 2次地震前兆的单键群构架的信源熵、平均键长和累积滑动频次进行了时空扫描 .结果表明 ,地震前单键群构架异常非常明显 ,并且可以... 利用单键群分析方法 ,对 1 976年唐山和 1 989年大同地震前多学科前兆异常的时空群集特征进行了研究 .对 2次地震前兆的单键群构架的信源熵、平均键长和累积滑动频次进行了时空扫描 .结果表明 ,地震前单键群构架异常非常明显 ,并且可以分为 5个阶段 .1 975年 6月~ 1 976年 6月 (第 4阶段 )异常幅度变化最大 .震前 1个月(第 5阶段 )信源熵值进一步下降 ,平均键长变化维持在第 4阶段的水平 ,累积滑动频次增加 .异常的变化阶段可为地震的中短期预报提供判据 .最小信源熵的变化经历了一个由外围逐渐向未来地震区迁移的过程 。 展开更多
关键词 唐山地震 地震前兆 大同地震 单键群 时空群集特征
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唐山祥云湾海洋牧场海域网采浮游植物群集特征研究
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作者 彭海 尤凯 +3 位作者 符子峻 王品杰 张沛东 张云岭 《海洋与湖沼》 CAS CSCD 北大核心 2023年第4期1070-1084,共15页
为研究唐山祥云湾海洋牧场海域网采浮游植物群集特征,于2020年11月至2021年11月在祥云湾海洋牧场海域进行了浮游植物及环境因子的周年逐月调查。共鉴定浮游植物41属78种其中硅藻33属62种,甲藻7属15种,硅鞭藻1属1种,年均丰度为205.58... 为研究唐山祥云湾海洋牧场海域网采浮游植物群集特征,于2020年11月至2021年11月在祥云湾海洋牧场海域进行了浮游植物及环境因子的周年逐月调查。共鉴定浮游植物41属78种其中硅藻33属62种,甲藻7属15种,硅鞭藻1属1种,年均丰度为205.58×10^(4)cells/m^(3),多样性指数H′为2.88。与近岸非增殖海域不同,该海域浮游植物的丰度及群落结构指数在春夏季水生生物繁生期达到全年最低。优势类群的季节演替明显,其中,3~5月以诺氏海链藻最占优势,9~10月以角毛藻和中肋骨条藻最占优势,周年优势类群以圆筛藻和角毛藻最占优势,其优势度变动在6月前以圆筛藻显著为高,之后则以角毛藻显著为高;此外,甲藻的优势度在泛冬季(11~2月)达到最高。鱼礁区与对照区的对比结果显示,两区域浮游植物的群落变化均可划分为泛冬季低温期(11~2月)、春夏季繁生期(3~6月)、泛秋季降温期(7~11月)三个时期。链状浮游植物的丰度在礁区明显高于对照区,而非链状浮游植物则相反;与生物作用关系密切的溶解有机碳、pH值在礁区低于对照区,而总磷和溶解态硅则相反。Pearson相关及冗余分析(RDA)显示,两区域浮游植物与环境因子的显著相关关系在不同时期差异明显。春夏季繁生期牡蛎礁上的贝类滤食活跃,浮游植物与环境因子的关系最为密切浮游植物与环境因子的相关关系达到显著水平的数量最多。礁区与对照区浮游植物的群集特征差异可能受到礁体附着生物活动及潮汐往复流混合作用的影响。 展开更多
关键词 浮游植物 群集特征 环境因子 海洋牧场 祥云湾
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基于核PCA的混合教学数据特征分析与分级 被引量:1
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作者 周静 熊骏 陈泽 《数字技术与应用》 2020年第11期187-189,共3页
针对目前教学数据挖掘与分析多考虑在线学习特征数据,而缺乏对传统课堂和在线教学的混合数据的融合分析,所建立评价模型也多以教师为主体,鲜少考虑学生个体质量分级等问题,本文研究了混合教学数据的非线性群集特征提取方法,采用核主成... 针对目前教学数据挖掘与分析多考虑在线学习特征数据,而缺乏对传统课堂和在线教学的混合数据的融合分析,所建立评价模型也多以教师为主体,鲜少考虑学生个体质量分级等问题,本文研究了混合教学数据的非线性群集特征提取方法,采用核主成分分析法对非线性混合学习特征数据进行降维计算,根据特征的权值大小提取影响学生学习质量的主要特征群集并得到多级特征指标,构建混合教学模式下学生个体质量的综合评价指标体系,并采用综合评价法确定多级评价指标的权重,建立学生个体综合评价与分级模型,并以本校公共课的混合教学数据为例,验证了模型的有效性。 展开更多
关键词 混合教学数据 核主成分分析 特征群集 评价体系 分级模型
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会计师事务所选择缘何“群集”——内聚性效应还是结构等价性效应? 被引量:1
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作者 张娆 《财经问题研究》 CSSCI 北大核心 2015年第4期61-67,共7页
中国上市公司在选择会计师事务所时呈现出"群集"特征,本文从公司间关系视角基于内聚性和结构等价性理论解释此特征。基于中国2007年A股上市公司的数据,使用QAP分析方法,研究发现:(1)通过连锁董事和相同实际控制人联系两家公司... 中国上市公司在选择会计师事务所时呈现出"群集"特征,本文从公司间关系视角基于内聚性和结构等价性理论解释此特征。基于中国2007年A股上市公司的数据,使用QAP分析方法,研究发现:(1)通过连锁董事和相同实际控制人联系两家公司,倾向于选择同一家事务所,即公司选择事务所呈现出内聚性效应。(2)地处相同地区和隶属于相同行业的两家公司,倾向于选择同一家会计师事务所,即公司选择事务所呈现出结构等价性效应。(3)四种关系影响强度从大到小依次为相同地区、连锁董事、相同实际控制人和相同行业。上述结论不仅在理论上表明公司间网络关系会影响公司的会计师事务所选择,同时在实践方面为相关政策提供了有益启示。 展开更多
关键词 会计师事务所 群集特征 公司间关系 内聚性 结构等价性
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基于稀疏凸非负矩阵分解的混合数据特征提取与评价研究
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作者 周静 余超 +1 位作者 胡怡宇 杜倩倩 《江汉大学学报(自然科学版)》 2021年第3期56-63,共8页
针对目前缺乏对在线教学和传统课堂的混合数据融合分析,提出一种改进的凸非负矩阵分解特征提取算法,可有效提取学生学习行为数据的特征群集。根据群集特征的权值大小,依次选取多级特征指标,构建评价层、群集层、特征层3个层次上的PSR评... 针对目前缺乏对在线教学和传统课堂的混合数据融合分析,提出一种改进的凸非负矩阵分解特征提取算法,可有效提取学生学习行为数据的特征群集。根据群集特征的权值大小,依次选取多级特征指标,构建评价层、群集层、特征层3个层次上的PSR评价指标体系。依据评价指标体系采用综合加权法计算学生个体的质量评价值,对个体进行分级,分级结果与学生期末考试成绩分级分布基本一致,且符合正态分布,证明了特征提取方法及评价分级模型的有效性。 展开更多
关键词 特征网络 群集特征 稀疏化 凸非负矩阵分解 PSR评价体系 分级模型
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基于支持向量机的B细胞线性表位预测模型 被引量:1
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作者 侯逸琳 《河北省科学院学报》 CAS 2019年第2期20-23,共4页
B细胞表位预测在蛋白抗体制备、疫苗设计中都具有重要的应用。基于支持向量机方法设计了一个B细胞线性表位预测模型,运用了多群集特征选择算法进行特征选择,有效提高了预测准确率。
关键词 B细胞 线性表位预测 支持向量机 群集特征选择
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Clustering-driven watershed adaptive segmentation of bubble image 被引量:7
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作者 周开军 阳春华 +1 位作者 桂卫华 许灿辉 《Journal of Central South University》 SCIE EI CAS 2010年第5期1049-1057,共9页
In order to extract froth morphological feature,a bubble image adaptive segmentation method was proposed.Considering the image's low contrast and weak froth edges,froth image was coarsely segmented by using fuzzy ... In order to extract froth morphological feature,a bubble image adaptive segmentation method was proposed.Considering the image's low contrast and weak froth edges,froth image was coarsely segmented by using fuzzy c means(FCM) algorithm. Through the attributes of size and shape pattern spectrum,the optimal morphological structuring element was determined.According to the optimal parameters,some image noises were removed with an improved area opening and closing by reconstruction operation,which consist of image regional markers,and the bubbles were finely separated from each other by watershed transform.The experimental results show that the structural element can be determined adaptively by shape and size pattern spectrum,and the froth image is segmented accurately.Compared with other froth image segmentation method,the proposed method achieves much high accuracy,based on which,the bubble size and shape features are extracted effectively. 展开更多
关键词 FLOTATION froth image adaptive segmentation pattern spectrum morphological feature
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Photoabsorption Spectra of Si_n and Si_nO (n ≤ 5)
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作者 AN Fang-Fang ZHANG Hong CHENG Xin-Lu 《Communications in Theoretical Physics》 SCIE CAS CSCD 2009年第4期751-755,共5页
The photoabsorption spectra have been calculated for Sis and SilO (n ≤ 5) clusters using time-dependent density-function theory. Our studies suggest that Sin-1 O clusters are relatively stable than those of corresp... The photoabsorption spectra have been calculated for Sis and SilO (n ≤ 5) clusters using time-dependent density-function theory. Our studies suggest that Sin-1 O clusters are relatively stable than those of corresponding Sis clusters. Moreover, substantial differences are observed among the absorption spectra of different molecules in the energy region (0 - 8 eV). Comparing two different exchange-correlation potentials, local-density and generalized-gradient approximations, both calculated optical spectra present the same spectral feature. 展开更多
关键词 Sin clusters SinO clusters TDDFT photoabsorption spectra
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Influence of Bioregulator Gibberellic Acid on Some Technological Characteristics of Cluster and Berry from Some Seedless Grape Varieties
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作者 V. Dimovska V. Ivanova F. Ilieva E. Sofijanova 《Journal of Agricultural Science and Technology(B)》 2011年第7期1054-1058,共5页
Solutions of gibberellic acid prepared at three concentration levels including 5, 10 and 20 mg/L, were applied at two seedless grape varieties, Thompson and Belgrade, by spraying, during the three different periods of... Solutions of gibberellic acid prepared at three concentration levels including 5, 10 and 20 mg/L, were applied at two seedless grape varieties, Thompson and Belgrade, by spraying, during the three different periods of the vine growing: before blooming, after blooming and before veraison, in order to study their influence on some cultural technological characteristics. Dimension and shape of the cluster and berry, mechanical characteristics of the berries and chemical content of the must (sugar and total acids) has been also investigated. It was noticed that the concentration of gibberellic acid had influence on the technological characteristics of the berries in all grape growing periods tested. The addition of gibberellic acid at concentration of 20 mg/L increased the weight of the cluster and berry, and increased the transportability of the berries belonging to the two seedless varieties. 展开更多
关键词 Gibberellic acid grape cluster BERRY Thompson Belgrade seedless varieties.
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THE ACTION OF THE LINEAR CHARACTERGROUP ON THE SET OF NON-LINEARIRREDUCIBLE CHARACTERSTHE ACTION OF THE LINEAR CHARACTERGROUP ON THE SET OF NON-LINEARIRREDUCIBLE CHARACTERS 被引量:3
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作者 RENYONGCAI LIXIANGYANG 《Chinese Annals of Mathematics,Series B》 SCIE CSCD 2000年第4期511-524,共14页
Let G be a nonabelian finite group. Then Irr(G/G’) is an abelian group under the multiplication of characters and acts on the set of non-linear irreducible characters of G via the multiplication of characters. The pu... Let G be a nonabelian finite group. Then Irr(G/G’) is an abelian group under the multiplication of characters and acts on the set of non-linear irreducible characters of G via the multiplication of characters. The purpose of this paper is to establish some facts about the action of linear character group on non-linear irreducible characters and determine the structures of groups G for which either all the orbit kernels are trivial or the number of orbits is at most two. Using the established results on this action, it is very easy to classify groups G having at most three non-linear irreducible characters. 展开更多
关键词 Finite group CHARACTER Action Orbit
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Symptom clustering in chronic gastritis based on spectral clustering 被引量:2
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作者 Wenhua Zhu Zhaoxiang Fan +5 位作者 Guoping Liu Jianjun Yan Tao Zhong Wu Zheng Ruiqing Wang Chunying Wang 《Journal of Traditional Chinese Medicine》 SCIE CAS CSCD 2014年第4期504-510,共7页
OBJECTIVE: Apply spectral clustering to analyze the patterns of symptoms in patients with chronic gastritis(CG).METHODS: Based on 919 CG subjects, we applied mutual information feature selection to choose the positive... OBJECTIVE: Apply spectral clustering to analyze the patterns of symptoms in patients with chronic gastritis(CG).METHODS: Based on 919 CG subjects, we applied mutual information feature selection to choose the positively correlated symptoms with each pattern.Then, we used the Shi and Malik spectral clustering algorithm to select the top 20 correlated symptoms.RESULTS: We ascertained the results of six patterns.There were three categories for the pattern of accumulation of damp heat in the spleen-stomach(0.00332). There were six categories for the pattern of dampness obstructing the spleen-stomach(0.02466). There were two categories for the pattern of spleen-stomach Qi deficiency(0.013 89).There were three categories for the pattern of spleen-stomach deficiency cold(0.009 15). There were five categories for the pattern of liver-Qistagnation(0.01910).There were four categories for the pattern of stagnant heat in the liver-stomach(0.00585).CONCLUSION: Most of the spectral clustering results of the symptoms of CG patterns were in accordance with clinical experience and Traditional Chinese Medicine theory. Most categories suggested the nature and/or location of the disease. 展开更多
关键词 Gastritis Cluster analysis Pattern Symptom complex
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Self-organizing dual clustering considering spatial analysis and hybrid distance measures 被引量:10
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作者 JIAO LiMin LIU YaoLin ZOU Bin 《Science China Earth Sciences》 SCIE EI CAS 2011年第8期1268-1278,共11页
Dual clustering performs object clustering in both spatial and non-spatial domains that cannot be dealt with well by traditional clustering methods.However,recent dual clustering research has often omitted spatial out... Dual clustering performs object clustering in both spatial and non-spatial domains that cannot be dealt with well by traditional clustering methods.However,recent dual clustering research has often omitted spatial outliers,subjectively determined the weights of hybrid distance measures,and produced diverse clustering results.In this study,we first redefined the dual clustering problem and related concepts to highlight the clustering criteria.We then presented a self-organizing dual clustering algorithm (SDC) based on the self-organizing feature map and certain spatial analysis operations,including the Voronoi diagram and polygon aggregation and amalgamation.The algorithm employs a hybrid distance measure that combines geometric distance and non-spatial similarity,while the clustering spectrum analysis helps to determine the weight of non-spatial similarity in the measure.A case study was conducted on a spatial database of urban land price samples in Wuhan,China.SDC detected spatial outliers and clustered the points into spatially connective and attributively homogenous sub-groups.In particular,SDC revealed zonal areas that describe the actual distribution of land prices but were not demonstrated by other methods.SDC reduced the subjectivity in dual clustering. 展开更多
关键词 dual clustering DATAMINING self-organizing feature map Voronoi diagram
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