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Hilbert-Huang变换方法(HHT)是针对非线性、非平稳序列的一种新的时间序列分析方法.针对前人在应用中存在的忽略统计检验的问题,提出了对本质模态函数(IMF)的周期进行T检验的改进方法,设计了基于T检验的HHT模型计算步骤和算法流程,可检验IMF周期的有效性.将改进后的HHT方法用于长江宜昌水文站50年的逐日径流量的分析中,得到了14个反映径流序列波动规律的IMF、一个反映径流变化趋势的趋势项r及Hilbert谱.研究表明,宜昌站径流量存在1~3a、4~5a、9a及准14a的年际变化周期,年内波动对整个径流序列的影响亦较大.对比分析表明了所设计的基于T检验的HHT方法的有效性.
Hilbert-Huang transform (HHT) is a new time series analysis method for non-linear and non-stationary sequences. Aiming at the problem of ignoring statistical tests in the past, , We design an improved HHT model based on T-test to calculate the steps and the algorithm flow, and test the validity of the IMF cycle.The improved HHT method is applied to 50-year daily runoff of Yichang hydrological station In the analysis, 14 IMFs reflecting the fluctuation of runoff series and a trend term r and Hilbert spectrum reflecting the trend of runoff are obtained. The results show that there are 1 ~ 3a, 4 ~ 5a, 9a and 14th years of Yichang station runoff During the year, the fluctuation has a great influence on the whole runoff sequence, and the comparative analysis shows the validity of the designed HHT method based on T-test.