huang本人在文章The empirical mode decomposition and the Hilbert spectrum for nonlinear and non-stationary time series analysis(huang1998)中的988-989页,提到这样simple means of successive extrema instead from the envelope mean,在这里simple means of successive extrema是啥意思?我问的不是单词怎么翻译,是在信号处理中的具体过程!谢谢各位!