中文摘要：

针对局域波分解过程中由于噪声导致模态混叠问题，应用提升小波变换对信号进行预处理，消除噪声对局域波分解的影响，改善了局域波分解质量，避免了局域波分解过程中虚假模式分量的产生。对于转子系统碰摩故障诊断中微弱冲击性故障特征难于提取的问题，应用该方法对转子振动测试信号进行分析，然后对分解得到的高频基本模式分量进行Hilbert包络解调分析，可以得到冲击响应信号出现的周期，准确提取了转子碰摩故障的特征信息。转子碰摩故障实验数据的分析结果证明了方法的有效性，可望应用于工程实际。

英文摘要：

Aiming at the mode mixture in local wave decomposition （LWD） caused by noise signal, the original data are preprocessed using lifting wavelet transformation to suppress abnormal interference of noise and improve the quality of decomposition, and avoid pseudo mode functions in LWD. This method is employed to analyze the vibration signal of rotor rub-impact for extracting the weak impulsive feature. The signal is decomposed into intrinsic mode functions with LWD; then the high-frequency components are analyzed using Hilbert envelope demodulation. The period of the impulse response can be obtained, and the fault feature of the vibration signal of a rotor system with rub-impact fault can be extracted accurately. Experiment analysis results show that the proposed method is accurate and efficient, and is expected to be applied in engineering practice effectively.