地震动瞬时谱估计的UnscentedKalman滤波方法

用时变ARMA模型描述地震动时程，提出了采用Unscented Kalman滤波技术实现地震动瞬时谱估计的思路．算例分析表明，Unscented Kalman滤波方法较Kalman滤波方法适用范围广，具有较高的时间和频率分辨率，能够更好地跟踪地震动的局部特性，适合处理非线性模型或有突变特性的模型的辨识问题．不同阶数ARMA模型的估计结果还表明，以往被忽略的ARMA模型的理论频率分辨力对地震动瞬时谱估计精度有重要影响，应作为一个参考指标在ARMA模型的判阶中加以考虑．

Instantaneous Spectrum Estimation of Earthquake Ground Motions Based on Unscented Kalman Filter Method

Representing earthquake ground motion as time varying ARMA model,the instantaneous spectrum can be determined only by the time varying coefficients of the corresponding ARMA model.Then,unscented Kalman filter was introduced to estimate the time varying coefficients.The comparison between the estimation results of unscented Kalman filter and Kalman filter method shows that unscented Kalman filter can more precisely represent the distribution of the spectral peaks in time-frequency plane than Kalman filter and its time and frequency resolution is finer which ensures its better ability to track the local properties of earthquake ground motions and to identify the systems with nonlinearity or abruptness.Moreover,the estimation results of ARMA models with different orders indicate that the theoretical frequency resolving power of ARMA model which was usually ignored in former relevant studies has great effect on the estimation precision of instantaneous spectrum and it should be taken as one of the key factors in order selection of ARMA model.