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非平稳信号的分析方法是信号分析领域中的一个重要问题。以风洞试验获得的非平稳风压信号和升力系数信号为研究对象,采用HHT方法对信号进行时频分析。HHT(Hilbert-Huang transform)方法可以获得有意义的瞬时频率,从而给出频率随时间变化的精确表达;信号最终被表示为时频平面上的能量分布,成为Hilbert谱;该方法适用于分析生活中普遍存在的大量频率随时间变化的非线性、非平稳信号,可将复杂的信号直接分离成从高频到低频的若干阶固有模态函数。分析结果虽然没有表现出明显的频谱分布特性,但与以往HHT分析结果提取的固有模态函数不同,如果对该试验获得的非平稳信号提取的固有模态是低频部分的残余信号,忽略其他高频信号,则风压时程和升力系数时程的残余信号曲线就可以分别回归为一个线性函数和一个正弦函数。这也说明,该非平稳信号的主成分仍然是由平稳信号组成的,可以用分析平稳信号的方法进行时程分析。
Non-stationary signal analysis method is an important issue in the field of signal analysis. The non-stationary wind pressure signal and lift coefficient signal obtained from the wind tunnel test were used as the research object, and the signal was analyzed by time-frequency analysis using HHT method. HHT (Hilbert-Huang transform) method can obtain meaningful instantaneous frequency, which gives accurate expression of frequency changes with time; the signal is finally expressed as the energy distribution in the time-frequency plane, a Hilbert spectrum; the method is suitable for analysis of life , A large number of non-linear and non-stationary signals with frequency variations prevailing in time are used to directly separate complex signals into several orders of intrinsic mode functions from high frequency to low frequency. Although the analysis results do not show obvious spectral distribution, the inherent modal functions extracted from the previous HHT analysis results are different. If the intrinsic mode extracted from the nonstationary signal obtained in this experiment is the residual signal of the low frequency part, the other high Frequency signal, the residual signal curve of the wind pressure time history and lift coefficient time history can be respectively regressed as a linear function and a sine function. This also shows that the main component of the non-stationary signal is still composed of a stationary signal, you can use the method of analysis of stationary signals for time-history analysis.