基于EMD和STFT柴油机缸盖振动信号时频分析

以柴油机缸盖振动信号为研究对象，提出经验模式分解（EMD）和短时傅里叶变换（STFT）相结合的时频分析法。该方法首先利用EMD对缸盖振动信号进行自适应分解，得到一系列本征模态分量（IMF）。根据各分量的特点有针对性地选择高斯窗和汉明窗分别进行STFT，并以时频聚集性指标为目标函数计算各分量的最佳时频分布，最后叠加得到原始信号的最佳时频分布。经对比分析，该方法解决了窗函数及窗宽的选择问题，有效提高STFT的时频分辨率，准确描述柴油机缸盖振动信号的时频分布。

Time-frequency Analysis of Vibration Signal from Cylinder Head of a Diesel Engine Based on EMD and STFT

A Time-Frequency analysis method based on empirical mode decomposition (EMD) and Short Time Fourier Transform (STFT) was put forward to research the vibration signal from cylinder head of diesel. The vibration signal was self adapting decomposed by EMD, and series of IMF were get. Gauss window and Hamming window were chosen to STFT according to different IMF, the Time-Frequency aggregation index was used as an object function so as to calculate the best Time-Frequency distribution of each IMF, then add them to get the best Time-Frequency distribution of origin signal. From comparison, this method settled the selection problem of window, effectively increased the Time-Frequency resolution of STFT, and described Time-Frequency distribution of vibration signal from cylinder head exactly