Application of Complex Three-Order Cumulants to Fault Diagnosis of Hydraulic Valve

为了提高故障诊断正确率,提出了一种基于复数三阶累积量的机械故障诊断方法.三阶累积量的不同定义的复数形式包含了信号间不同的耦合信息,利用这些信息进行了故障诊断.在溢流阀故障诊断实验中,利用这些不同的耦合信息,通过二维小波在不同的方向上对故障信号和正常信号进行特征提取,然后将这些特征值输入支持向量机进行故障判别.实验结果表明,上述方法可以提高故障诊断正确率.同时还对实数三阶累积量也进行了相同的实验,这些实验所取得的诊断效果证明了采用本文方法的有效性.In order to improve the correction rate of fault diagnosis,one method of mechanical fault diagnosis based on complex three-order cumulants was proposed.The complex forms with different definitions of three-order cumulants included different coupling information of signals,which was used to diagnose fault.In the experiment on the fault diagnosis of overflow valve,using the different coupling information,the features of fault signals and normal signals were extracted by 2-D wavelet in different directions,and then they were input into support vector machine to diagnose the fault.The experiment results show that this method can improve the correction rate of diagnosis.Furthermore,the same experiment was performed on the real three-order cumulants,and the results verify the effectiveness of the method proposed in this paper.国家自然科学基金资助项目(50975098

圣·约翰草提取物片治疗抑郁障碍专家共识

结合循证医学证据,本文归纳圣·约翰草提取物片治疗抑郁障碍的专家共识

鸟类飞羽羽轴髓质结构的定量分析

鸟类飞羽羽轴机械性能一部分来自髓质,但是髓质泡沫结构如何影响羽轴机械性能的问题仍未被研究。本文对5种鸟类初级飞羽羽轴的髓质形态结构进行研究,测定了腔室的大小、壁厚度等形态计量学参数,分析了这些结构参数与体重的关系以及腔室在抵抗形变的作用过程。结果显示,髓质腔室断面的平均周长（l,表示腔室的大小）介于74.26±11.27～153.02±59.01μm之间,在一些种类（如丹顶鹤和毛脚鵟）,外周髓质的l值显著大于中央髓质（P0.05）;腔室壁厚度（t）介于0.51±0.15～2.14±1.11μm之间,在所有种类外周髓质的t值均显著（P0.05）,但是外周髓质的t值与翈面面积、体重均呈显著的线性相关（P<0.05）。上述结果表明,空球形腔室可以把某一点上的压力有效地传递和分配到整个羽轴内部,并在每个形变的腔室壁上积累势能;外周髓质对羽轴机械性能的贡献大于中央髓质,这种贡献主要缘于腔室壁的厚度而不是腔室的大小。但是,腔室大小在不同鸟类显出与扑翼强度相一致的关系