振动信号是风电机组数据采集与监控系统（supervisory control and data acquisition system，SCADA）中一类重要变量。以风电机组SCADA运行数据为基础，首先结合风机运行原理详细分析了导致塔架振动的主要因素。进而采用相对主元分析（...振动信号是风电机组数据采集与监控系统（supervisory control and data acquisition system，SCADA）中一类重要变量。以风电机组SCADA运行数据为基础，首先结合风机运行原理详细分析了导致塔架振动的主要因素。进而采用相对主元分析（relative principal component analysis，RPCA）和某风电机组2011年3～5月份的SCADA运行数据，建立了覆盖塔架正常工作状态的RPCA振动模型，计算得出监控统计量Hotelling T2（简称T2）和平方预测误差（squared prediction error，SPE）。采用塔架振动RPCA模型，准确检测出风电机组变桨系统故障，验证了所研究方法的有效性。展开更多
Despite the widespread endorsing of multiculturalism, the progress of enquiry into it and multicultural education have been impeded by a suspicion of cultural relativism and intellectual insularity. This paper reveals...Despite the widespread endorsing of multiculturalism, the progress of enquiry into it and multicultural education have been impeded by a suspicion of cultural relativism and intellectual insularity. This paper reveals that such a suspicion is spurious by paying special attention to the notion of＂standpoint＂ which has a relative but substantial effect. The proper recognition of this point highlights the sense in which the insights drawn from multiculturalism and their educational embodiments are crucial for the future of humanity as a whole, which is far beyond the enduring controversy about universality and particularity.展开更多
文摘传统主元分析(Principal component analysis,PCA)方法因忽视量纲对系统的影响,从而使选取的主元难以具有代表性;而在进行量纲标准化后,又因得到的特征值常常是近似相等的而无法进行有效的主元提取.针对这一主要问题,本文通过引入相对化变换(Relative transform,RT)、相对主元(Relative principal components,RPCs)和分布"均匀"等概念,建立起一种相对主元分析(Relative principal component analysis,RPCA)的新方法.该方法首先对系统各分量进行量纲标准化;其次再根据系统的先验信息分析和确定各分量的重要程度;然后在系统能量守恒的准则下,赋以系统各分量相应的权值;最后利用已建立起的相对主元模型,对系统实施RPCA.同时运用数值例子,开展了RPCA在数据压缩和系统故障诊断中的应用研究.理论分析和仿真实验均表明,采用RPCA方法选取出的主元更具代表性和显著几何意义,加之选取主元的灵活性,将使新方法具有更广泛的应用前景。
文摘振动信号是风电机组数据采集与监控系统（supervisory control and data acquisition system，SCADA）中一类重要变量。以风电机组SCADA运行数据为基础，首先结合风机运行原理详细分析了导致塔架振动的主要因素。进而采用相对主元分析（relative principal component analysis，RPCA）和某风电机组2011年3～5月份的SCADA运行数据，建立了覆盖塔架正常工作状态的RPCA振动模型，计算得出监控统计量Hotelling T2（简称T2）和平方预测误差（squared prediction error，SPE）。采用塔架振动RPCA模型，准确检测出风电机组变桨系统故障，验证了所研究方法的有效性。
文摘Despite the widespread endorsing of multiculturalism, the progress of enquiry into it and multicultural education have been impeded by a suspicion of cultural relativism and intellectual insularity. This paper reveals that such a suspicion is spurious by paying special attention to the notion of＂standpoint＂ which has a relative but substantial effect. The proper recognition of this point highlights the sense in which the insights drawn from multiculturalism and their educational embodiments are crucial for the future of humanity as a whole, which is far beyond the enduring controversy about universality and particularity.
