中文摘要：

局部均值分解（Local mean decomposition,LMD）在分析非线性、非平稳信号时表现出特有的分析能力,能够有效获得非平稳信号的时频特征,但是局部均值分解过程中的端点效应会导致分解结果失真,针对这一问题,从振动信号解调分析角度出发,提出基于对称差分能量算子解调的局部均值分解端点效应抑制方法,采用局部均值分解方法将原信号分解为一系列单分量信号,然后对每一个单分量信号进行三点对称差分能量算子解调,得到各单分量信号的瞬时幅值和瞬时频率,从而获得原信号的时频分布.为评价该端点效应抑制方法的抑制效果,定义一种评价标准,通过与其他两种端点效应抑制方法进行比较,验证该方法的优越性.仿真和试验结果表明该方法能够有效抑制LMD端点效应,实现旋转机械故障的有效诊断.

英文摘要：

The local mean decomposition （LMD） method presents its own ability for processing nonlinear and non-stationary signals.It can effectively obtain the time-frequency characteristics of non-stationary signals.But there is an involved end effect in the course of local mean decomposition,and the end effect can cause the distortion of decomposition results.Based on the demodulation analysis of vibration signal,a new method for restraining the end effects of local mean decomposition based on the energy operator demodulation of symmetrical differencing.The signal is decomposed into a series of single component signals by the local mean decomposition method,then each single component signal can be demodulated by the method of symmetrical differencing energy operator,and the instantaneous amplitude and instantaneous frequency of each single component signal can be got,the time-frequency distribution of the signal is obtained.To evaluate the effect of endpoint suppression method,an evaluation criterion is defined,compared with the other two endpoint effect suppression methods,the superiority of the proposed method is verified.The results of simulation and practical signal analysis show that the method can restrain the end effects of LMD and implement rotating machinery fault diagnosis effectively.