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网络流量自相关模型的点过程识别
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作者 许立波 吴国新 +1 位作者 张三峰 于坤 《通讯和计算机(中英文版)》 2006年第2期48-55,共8页
在细粒度时间尺度上,伸统的随机点过程类模型对网络流量的拟合仍然是较为合适的模型,如MMPP。不同于大多数数学意义上的适配模型,本文通过对样本数据直接提取统计特征来估计模型参数,使用方差加权距离聚类分离样本数据估算MMPP状态... 在细粒度时间尺度上,伸统的随机点过程类模型对网络流量的拟合仍然是较为合适的模型,如MMPP。不同于大多数数学意义上的适配模型,本文通过对样本数据直接提取统计特征来估计模型参数,使用方差加权距离聚类分离样本数据估算MMPP状态的强度,计算状态转移频数以估计一步转移概率矩阵,通过该矩阵估算转移速率矩阵,建立起样本数据和适配模型物理意义上的高度契合。最后针对模拟流量的统计特性和队列特性,用适配结果进行检验,证明了该方案的有效性。 展开更多
关键词 随机点过程 MMPP 聚期分析 MARKOV链
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Identification of Drought Tolerance in Peanut (Arachis hypogaea) Germplasm at Seedling Stage 被引量:2
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作者 刘永惠 沈一 陈志德 《Agricultural Science & Technology》 CAS 2015年第9期1873-1876,共4页
[Objective] This study was conducted to identify the drought tolerance of peanut(Arachis hypogaea) seedlings. [Method] The plant height, fresh weight and dry weight of 80 peanut varieties or lines were determined un... [Objective] This study was conducted to identify the drought tolerance of peanut(Arachis hypogaea) seedlings. [Method] The plant height, fresh weight and dry weight of 80 peanut varieties or lines were determined under the drought stress simulated using 15% PEG6000 in laboratory. Relative values of the three indices were calculated to measure the drought tolerance of the 80 peanut varieties or lines. [Result] The growth of peanut seedlings was significantly inhibited after 10 d of drought treatment. Cluster analysis revealed that at Euclidean distance D=15, the80 peanut varieties or lines were divided into four categories A, B, C and D. Among them, category B had better drought tolerance while category C was sensitive to drought. In all the four categories, the approved peanut varieties or lines showed better drought tolerance than the unapproved ones. [Conclusion] The drought tolerant and the drought sensitive peanut varieties or lines screened in this study can be used for further basic research and germplasm improvement. 展开更多
关键词 PEANUT SEEDLING Drought tolerance Cluster analysis
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Study on Phenological Character in Seedling Period of Introduced Populus deltoids Clones 被引量:2
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作者 唐洁 汤玉喜 +4 位作者 苏晓华 李永进 黄秦军 吴敏 杨艳 《Agricultural Science & Technology》 CAS 2014年第3期422-426,共5页
In order to provide directionally genetically improved breeding materials of poplar by exploring the phenological traits genetic variation level and its develop- ment potential of Populus deltoides and the resource ev... In order to provide directionally genetically improved breeding materials of poplar by exploring the phenological traits genetic variation level and its develop- ment potential of Populus deltoides and the resource evaluation was carried out; 8 phenological phases in seedling period were observed and analyzed of 60 Populus deltoids clones introduced from America. The results showed that: (1) there was obvious difference in phonological character among clones, especially in leaf-spread- ing peak stage and the end term of leaf-falling stage, with the largest variation co- efficient of 14.97% and the minimum of 3.83% respectively. (2) Leaf-spreading peak stage scattered but the end term of leaf-falling stage concentrated the most. The phonological character in early stage of seedling growth was the main factor influ- encing the length of growing season. (3) By principal component analysis, pheno- logical phases were classified into 3 typical periods, including germination stage, leaf-spreading peak stage and leaf-falling stage. (4) Totaling 60 clones were classi- fied into 4 types by using clustering analysis in phenological time variables of clones. 展开更多
关键词 Populus deltoids CLONE Phenological phase Principal component analysis Clustering analysis
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