短样本条件下提高HHT识别模态参数精度的方法
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    摘要:

    由于在短样本条件下HilbertHuang变换(HilbertHuang transform,简称HHT)识别模态参 数 的精度主要受经验模态分解(empirical modal decomposition,简称EMD)模式混合和随机减 量法(random decrement technology,简称RDT)提取自由衰减响应时平均次数不足的影响, 针对这两个影响因素,引入带宽限制信号抑制EMD的模式混合,提高EMD的精度;并引入分层抽 样 技术,提出基于拟合偏差和样本量的层权确定方法来进行多次识别,然后加权平均,提高RDT的 总平均次数。仿真试验和应用实例表明,结合分层抽样的限制带宽EMD识别模态参数的方法能 提高短样本条件下HHT识别模态参数的精度。

    Abstract:

    Because the precision of modal parameter identification based on Hilbe rtHuang transform is affected by the mode mixture of empirical mode decomposit i on (EMD) and average times of random decrement technology (RDT), a novel modal p arameter identification method using stratified sampling and bandwidth restricte d EMD is proposed for short data sequences. A bandwidth restricting signal was e mployed in the procedure of EMD to restrain the mode mixture and to increase the frequency precision of EMD. In order to obtain more subdata sequences of RDT, stratified sampling, which took the place of random sampling and had the ability to improve precision of sampling and total average times, was employed to extra ct free decrement response signal. The method based on fitting difference and sa mple size was proposed to determine the layer’s weight of stratified sampling. The simulation and the application demonstrated that the proposed method is effe ctive and capable of improving precision of HHTbased modal parameter identific ation for short data sequences.

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  • 收稿日期:2009-02-27
  • 最后修改日期:2009-05-05
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