The plausibility relation which is generalization of fuzzy relation and probabilistic relation is proposed in thepaper. We think data mining to be a process of finding the plausibility relation in database and correla...The plausibility relation which is generalization of fuzzy relation and probabilistic relation is proposed in thepaper. We think data mining to be a process of finding the plausibility relation in database and correlativity measure tobe a particular plausibility relation based on correlativity sets. The critical calculates such as the accuracy of the roughsets, the confidence and the bayesian form in data mining can be united using the correlativity measure. The GPDM(General Process of Data Mining)that represents the nature of data mining is also proposed. The data mining theoreti-cal foundation and frameworks based on correlativity sets are also given and discussed in the paper.展开更多
针对现有配电网鲁棒调度方法缺乏对不确定参数相关性问题的考虑,提出了一种基于数据驱动多面体集合的交直流混合配电网鲁棒调度方法。首先,构建分布式光伏出力的传统多面体集合,利用历史数据驱动形成了相关性包络图,通过弯曲多面体集合...针对现有配电网鲁棒调度方法缺乏对不确定参数相关性问题的考虑,提出了一种基于数据驱动多面体集合的交直流混合配电网鲁棒调度方法。首先,构建分布式光伏出力的传统多面体集合,利用历史数据驱动形成了相关性包络图,通过弯曲多面体集合边界,建立了相关性多面体集合模型。然后,在此基础上,针对相关性多面体集合存在鲁棒性差和保守性大的问题,建立了数据驱动的多面体集合模型。进一步,建立了基于数据驱动多面体集合的交直流混合配电网鲁棒调度模型,并采用列与约束生成(column and constraint generation,CCG)算法对鲁棒调度模型进行求解。最后,改进的IEEE33节点系统仿真结果表明,基于数据驱动多面体集合的交直流混合配电网鲁棒调度方法可以减少优化结果的保守性,提高其鲁棒性,证明了所提出方法的有效性。展开更多
提出了基于相关邻近集合的能耗均衡多跳分簇路由协议(relative neighborhood set based distributed multi-hop clustering routing protocol,RNS-MCRP)。网络初始化阶段,基站计算若干个簇头节点以及所有节点的相关邻近集合,并广播簇头...提出了基于相关邻近集合的能耗均衡多跳分簇路由协议(relative neighborhood set based distributed multi-hop clustering routing protocol,RNS-MCRP)。网络初始化阶段,基站计算若干个簇头节点以及所有节点的相关邻近集合,并广播簇头信息和所有节点的相关邻近集合。网络启动后,所有节点根据簇头节点的位置信息划分自己的邻居集合,并从邻居集合中选择剩余能量最大的节点作为下一跳节点。簇头节点推举本簇内部最大剩余能量的节点作为下一轮的簇头节点。实验结果显示,与LEACH(low energy adaptive clustering hierarchy)协议相比较,RNS-MCRP具有更好的能耗均衡特性,提高了网络生命时间。展开更多
以中国夏季气温为预测对象,选取东亚地区冬季500 h Pa高度场、海平面气压场、地表温度场和850 h Pa温度场为预测因子,采用1951～2009年去趋势处理后的资料,通过变形的典型相关分析（Barnett-Preisendorfer Canonical Correlation Analys...以中国夏季气温为预测对象,选取东亚地区冬季500 h Pa高度场、海平面气压场、地表温度场和850 h Pa温度场为预测因子,采用1951～2009年去趋势处理后的资料,通过变形的典型相关分析（Barnett-Preisendorfer Canonical Correlation Analysis,BP-CCA）方法分别建立单因子预测模型,再利用集合典型相关分析（Ensemble Canonical Correlation,ECC）方法建立集合预测模型,对中国夏季气温进行基于交叉检验方法的预测试验,然后利用2010～2014年的资料对中国夏季气温进行独立样本检验。通过分析BP-CCA模态可知,一对BP-CCA模态的空间型在一定程度上可以反映预报因子场和对象场的遥相关特征。通过基于交叉检验方法的预测试验表明环流场和热力场均能为气温提供预测信息。ECC预测模型综合了各个预报因子的在不同地区的预报技巧,比单因子BP-CCA预测模型有更高、更稳定的预报技巧。独立样本检验表明ECC模型与单因子BP-CCA预测模型相比,对中国夏季气温有更高、更稳定的实际预测能力,对气温季节预测具有参考价值。展开更多
选取前期9、6和3个月欧亚大陆地表温度、东北半球500 h Pa高度场、热带印度洋海表面温度和西太平洋海表面温度作为预报因子,使用变形的典型相关分析(BP-CCA)方法,并选取各因子预报效果最好的时期作为关键时期,建立起各因子和青藏高原冬...选取前期9、6和3个月欧亚大陆地表温度、东北半球500 h Pa高度场、热带印度洋海表面温度和西太平洋海表面温度作为预报因子,使用变形的典型相关分析(BP-CCA)方法,并选取各因子预报效果最好的时期作为关键时期,建立起各因子和青藏高原冬季气温之间的统计降尺度模型。之后用交叉验证和集合典型相关分析(ECC)方法评估模型实际预报能力。进一步用独立样本检验来评估模型更长时间尺度的年际变化预测效果。结果表明,BP-CCA方法能很好地识别出不同因子影响青藏高原的空间模态。其中,温度积雪反照率的正反馈机制体现了欧亚大陆地表温度的可预报性;东北半球500 h Pa高度场环流型不利于高纬的冷空气入侵高原地区;热带印度洋海表面温度反映出典型的印度洋偶极子对高原气温的调控作用;西太平洋海表面温度通过控制副热带高压的位置,从而影响高原冬季气温。各因子预报场和观测场的相关系数在交叉检验和独立样本检验中分别约为0.5和0.3,均有一定的预报技巧。而利用ECC方法能综合各因子所提供的预报信息,从而得出更为可信和稳定的预报。展开更多
The small-island effect （SIE） has become more and more part of the theoretical framework of island biogeography and biodiversity research. However, previous methods for the detection of SlEs are often flawed in one ...The small-island effect （SIE） has become more and more part of the theoretical framework of island biogeography and biodiversity research. However, previous methods for the detection of SlEs are often flawed in one way or another, including not accounting for model complexity, not comparing all relevant models, and not including islands with no species. Therefore, the existence and the prevalence of the SIE may be dubious. In this study, after controlling for all these methodological shortcomings, we tested for the existence of the SlE in amphibian assemblages on subtropical landbridge islands created by the inundation of the Thousand Island Lake, China. We used the line transect method to determine the distribution of amphibian assemblages on 23 study islands during 3 breeding seasons from 2009 to 2011. To evaluate whether an SIE exists in amphibian assemblages, we compared the fit of a simple linearized power model with two most widely used breakpoint regression models. The information-theoretic multimodel inference approach based on Akaike＇s information criterion identified the left-horizontal SIE model as the best single model. Thus, we found strong evidence for the existence of an SIE in our system. The upper limit of the SlE for amphibian assemblages was 39.95 ha. Below this threshold area, amphibian richness varied independently of island size. The SlE in amphibian assemblages may be due to episodic disturbances, stochastic events, and nutrient subsidies from the lake. Our results indicate that all the islands 〉39.95 ha should be protected for the effective conservation of amphibian assemblages in our system.展开更多
文摘The plausibility relation which is generalization of fuzzy relation and probabilistic relation is proposed in thepaper. We think data mining to be a process of finding the plausibility relation in database and correlativity measure tobe a particular plausibility relation based on correlativity sets. The critical calculates such as the accuracy of the roughsets, the confidence and the bayesian form in data mining can be united using the correlativity measure. The GPDM(General Process of Data Mining)that represents the nature of data mining is also proposed. The data mining theoreti-cal foundation and frameworks based on correlativity sets are also given and discussed in the paper.
文摘针对现有配电网鲁棒调度方法缺乏对不确定参数相关性问题的考虑,提出了一种基于数据驱动多面体集合的交直流混合配电网鲁棒调度方法。首先,构建分布式光伏出力的传统多面体集合,利用历史数据驱动形成了相关性包络图,通过弯曲多面体集合边界,建立了相关性多面体集合模型。然后,在此基础上,针对相关性多面体集合存在鲁棒性差和保守性大的问题,建立了数据驱动的多面体集合模型。进一步,建立了基于数据驱动多面体集合的交直流混合配电网鲁棒调度模型,并采用列与约束生成(column and constraint generation,CCG)算法对鲁棒调度模型进行求解。最后,改进的IEEE33节点系统仿真结果表明,基于数据驱动多面体集合的交直流混合配电网鲁棒调度方法可以减少优化结果的保守性,提高其鲁棒性,证明了所提出方法的有效性。
文摘提出了基于相关邻近集合的能耗均衡多跳分簇路由协议(relative neighborhood set based distributed multi-hop clustering routing protocol,RNS-MCRP)。网络初始化阶段,基站计算若干个簇头节点以及所有节点的相关邻近集合,并广播簇头信息和所有节点的相关邻近集合。网络启动后,所有节点根据簇头节点的位置信息划分自己的邻居集合,并从邻居集合中选择剩余能量最大的节点作为下一跳节点。簇头节点推举本簇内部最大剩余能量的节点作为下一轮的簇头节点。实验结果显示,与LEACH(low energy adaptive clustering hierarchy)协议相比较,RNS-MCRP具有更好的能耗均衡特性,提高了网络生命时间。
文摘以中国夏季气温为预测对象,选取东亚地区冬季500 h Pa高度场、海平面气压场、地表温度场和850 h Pa温度场为预测因子,采用1951～2009年去趋势处理后的资料,通过变形的典型相关分析（Barnett-Preisendorfer Canonical Correlation Analysis,BP-CCA）方法分别建立单因子预测模型,再利用集合典型相关分析（Ensemble Canonical Correlation,ECC）方法建立集合预测模型,对中国夏季气温进行基于交叉检验方法的预测试验,然后利用2010～2014年的资料对中国夏季气温进行独立样本检验。通过分析BP-CCA模态可知,一对BP-CCA模态的空间型在一定程度上可以反映预报因子场和对象场的遥相关特征。通过基于交叉检验方法的预测试验表明环流场和热力场均能为气温提供预测信息。ECC预测模型综合了各个预报因子的在不同地区的预报技巧,比单因子BP-CCA预测模型有更高、更稳定的预报技巧。独立样本检验表明ECC模型与单因子BP-CCA预测模型相比,对中国夏季气温有更高、更稳定的实际预测能力,对气温季节预测具有参考价值。
文摘选取前期9、6和3个月欧亚大陆地表温度、东北半球500 h Pa高度场、热带印度洋海表面温度和西太平洋海表面温度作为预报因子,使用变形的典型相关分析(BP-CCA)方法,并选取各因子预报效果最好的时期作为关键时期,建立起各因子和青藏高原冬季气温之间的统计降尺度模型。之后用交叉验证和集合典型相关分析(ECC)方法评估模型实际预报能力。进一步用独立样本检验来评估模型更长时间尺度的年际变化预测效果。结果表明,BP-CCA方法能很好地识别出不同因子影响青藏高原的空间模态。其中,温度积雪反照率的正反馈机制体现了欧亚大陆地表温度的可预报性;东北半球500 h Pa高度场环流型不利于高纬的冷空气入侵高原地区;热带印度洋海表面温度反映出典型的印度洋偶极子对高原气温的调控作用;西太平洋海表面温度通过控制副热带高压的位置,从而影响高原冬季气温。各因子预报场和观测场的相关系数在交叉检验和独立样本检验中分别约为0.5和0.3,均有一定的预报技巧。而利用ECC方法能综合各因子所提供的预报信息,从而得出更为可信和稳定的预报。
基金The study was supported by the National Natural Science Foundation of China （31471981, 31100394, and 31210103908）, the Project-sponsored by SRF for ROCS, SEM （J20130585） and the Fundamental Research Funds for the Central Universities （2016QNA6001 ）.
文摘The small-island effect （SIE） has become more and more part of the theoretical framework of island biogeography and biodiversity research. However, previous methods for the detection of SlEs are often flawed in one way or another, including not accounting for model complexity, not comparing all relevant models, and not including islands with no species. Therefore, the existence and the prevalence of the SIE may be dubious. In this study, after controlling for all these methodological shortcomings, we tested for the existence of the SlE in amphibian assemblages on subtropical landbridge islands created by the inundation of the Thousand Island Lake, China. We used the line transect method to determine the distribution of amphibian assemblages on 23 study islands during 3 breeding seasons from 2009 to 2011. To evaluate whether an SIE exists in amphibian assemblages, we compared the fit of a simple linearized power model with two most widely used breakpoint regression models. The information-theoretic multimodel inference approach based on Akaike＇s information criterion identified the left-horizontal SIE model as the best single model. Thus, we found strong evidence for the existence of an SIE in our system. The upper limit of the SlE for amphibian assemblages was 39.95 ha. Below this threshold area, amphibian richness varied independently of island size. The SlE in amphibian assemblages may be due to episodic disturbances, stochastic events, and nutrient subsidies from the lake. Our results indicate that all the islands 〉39.95 ha should be protected for the effective conservation of amphibian assemblages in our system.
