用两个单频率三角函数信号模拟,然后对其做EEMD分解,得到Hilbert谱。请问怎样解释Hilbert谱中高频分量(40Hz)的波动呢?怎样对Hilbert谱进行分析呢?主要是模态混叠现象、端点效应。在对Hilbert谱分析方面,我看了HUANG和WU ZHAO HUA发明EEMD方法的文献《ensemble empirical mode decomposition: a noise assisted data analysis method》,文中说EEMD分解后的Hilbert谱比EMD改进的方面的描述是这样的:The mode mixing has almost completely disappeared.There are almost no transition gaps,and all basic frequency traces are continuous in the time-frequency space.请问“There are almost no transition gaps”怎样理解?谢谢!