A simulation method for nonstationary process is proposed based on the ensemble empirical mode decomposition (EEMD) and the empirical envelope (EE) methods: the EEMD is used to decompose a nonstationary process into several mono-component signals, and then the EE method is utilized to calculate the instantaneous characteristics of these mono-component signals; a simulated process can be constructed based on the distributions of the instantaneous characteristics of the mono-component signals. An earthquake ground motion recorded in chi-chi earthquake and a nonstationary wind speed induced by typhoon Rammasun are utilized to verify the accuracy and efficacy of the newly-developed method. Results show that: the EE method performs much better than the Hilbert transform (HT)-based method in calculating the instantaneous frequency; the proposed method can successfully capture the global and transient energy distributions of a nonstationary process; the nonstationary wind speed can be modeled as a uniformly modulated nonstationary process, while the earthquake ground motion should be modeled as a non-uniformly modulated nonstationary process. The proposed method does not include any pre-assumed modulation function or inappropriate assumption such as piece-wise stationarity. The method is applicable to the simulation of various types of nonstationary processes, and it can be extended to simulate multivariate nonstationary processes.

提出了一种基于整体经验模态分解（EEMD）和经验包络（EE）方法的非平稳过程仿真方法：利用EEMD将非平稳过程分解为几个单分量信号，然后利用EE方法计算这些单分量信号的瞬时特性；可以基于单分量信号的瞬时特性的分布来构建模拟过程。利用在集集地震中记录的地震地面运动和由台风拉玛森引起的非平稳风速来验证新方法的准确性和有效性。结果表明：EE方法在计算瞬时频率方面比基于Hilbert变换（HT）的方法要好得多。所提出的方法可以成功地捕获一个非平稳过程的全局和瞬时能量分布；可以将非平稳风速建模为均匀调制的非平稳过程，而将地震地面运动建模为非均匀调制的非平稳过程。所提出的方法不包括任何预先设定的调制函数或不适当的假设，例如分段平稳性。该方法适用于各种类型的非平稳过程的模拟，并且可以扩展为模拟多元非平稳过程。而地震地震动应建模为非均匀调制的非平稳过程。所提出的方法不包括任何预先设定的调制函数或不适当的假设，例如分段平稳性。该方法适用于各种类型的非平稳过程的模拟，并且可以扩展为模拟多元非平稳过程。而地震地震动应建模为非均匀调制的非平稳过程。所提出的方法不包括任何预先设定的调制函数或不适当的假设，例如分段平稳性。该方法适用于各种类型的非平稳过程的模拟，并且可以扩展为模拟多元非平稳过程。