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Extraction of failure characteristic of rolling element bearing based on wavelet transform under strong noise
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作者 张辉 王淑娟 《Journal of Harbin Institute of Technology(New Series)》 EI CAS 2005年第2期169-172,共4页
There has been a lot of research has been performed regarding diagnosing rolling element bearing faults using wavelet analysis, but almost all methods are not ideal for picking up fault signal characteristics under st... There has been a lot of research has been performed regarding diagnosing rolling element bearing faults using wavelet analysis, but almost all methods are not ideal for picking up fault signal characteristics under strong noise. Therefore, this paper proposes auto-correlation, cross-correlation and weighted average fault diagnosis methods based on wavelet transform (WT) de-noising which combine correlation analysis with WT for the first time. These three methods compute the auto-correlation, the cross-correlation and the weighted average of the measured vibration signals, then de-noise by thresholding and computing the auto-correlation of de-noised coefficients of WT and FFT of energy sequence. The simulation results indicate that all methods enhance the capabilities of fault diagnosis of rolling bearings and pick up the fault characteristics effectively. 展开更多
关键词 rolling bearing wavelet transform auto-correlation CROSS-CORRELATION weighted average
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鼻化特征在历史演变中的转移——从辅音声母到元音?还是元音到辅音声母?
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作者 Alexis Michaud Guillaume Jacques +1 位作者 Robert L.Rankin 衣莉 《东方语言学》 2014年第1期159-188,192-193,共31页
比较几个语系的相关数据可以看出鼻化特征的转移发生在音节首辅音丛和其后的元音之间。本文总结了迄今为止发现的数据,并针对一套汉藏语做了新的分析。显示这种演化在两个方向同时出现:从辅音声母到其后的元音出现在壮侗语系(台-卡岱语... 比较几个语系的相关数据可以看出鼻化特征的转移发生在音节首辅音丛和其后的元音之间。本文总结了迄今为止发现的数据,并针对一套汉藏语做了新的分析。显示这种演化在两个方向同时出现:从辅音声母到其后的元音出现在壮侗语系(台-卡岱语系)、南亚语系、汉藏语系、尼日尔-刚果语系(克瓦语)和印欧语系(凯尔特语)中;从元音向辅音声母的转移出现于苏语。仔细检验演化的条件,带出一条(规则的)不对称性。大多数情况下鼻化特征的转移是从辅音声母到其后的元音。相反方向的有规律的变化常常要附加下面任意一条对鼻音的限制条件:(i)鼻辅音为非音位性(语境可预测);或者(ii)鼻辅音后的鼻元音和口元音的对立发生中和(更倾向于鼻元音)。 展开更多
关键词 鼻音声母 鼻元音 鼻化 辅音丛 音系转换 泛时音系 音变模型
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