关键词: 经验模态分解（EMD）方法, 固有模态函数（IMF）, 异常事件, 频率混叠

Abstract: The frequency-mixing-producing mechanism is discussed and two prerequisites of its occurrence are concluded.Partial empirical model decomposition algorithm is proposed to deal with the frequency mixing problem.The algorithm locates short-time higher frequency components by probing jumps in the signal，and sets up local time windows to cover them.It adopts empirical model decomposition just within the windows to separate the short-time higher frequency components from background signal.In this way the intrinsic mode functions in the new result can reflect the temporal processes better.Partial empirical model decomposition method is simple，highly unified with the theory of empirical model decomposition.An application case shows the effective of the new method.

Key words: empirical model decomposition, intrinsic mode function, abnormal event, frequency mixing