基于ILMSST识别时变结构非平稳响应信号瞬时频率  

Instantaneous frequency estimation of nonstationary response signals of time-varying structures based on ILMSST

作　　者：刘景良 李宇祖 苏杰龙 骆勇鹏 盛叶 LIU Jingliang;LI Yuzu;SU Jielong;LUO Yongpeng;SHENG Ye(School of Transportation and Civil Engineering,Fujian Agriculture and Forestry University,Fuzhou 350108,China;“Digital Fujian”Laboratory of Internet Things for Intelligent Transportation Technology,Fuzhou 350108,China)

机构地区：[1]福建农林大学交通与土木工程学院,福建福州350108 [2]“数字福建”智能交通技术物联网实验室,福建福州350108

出　　处：《地震工程与工程振动》2024年第2期72-80,共9页Earthquake Engineering and Engineering Dynamics

基　　金：国家自然科学基金青年项目(51608122);中央引导地方科技发展专项(202L3007);福建省自然科学基金面上项目(2020J01581,2020J01579);福建农林大学优秀硕士学位论文基金项目(113/1122YS01005)。

摘　　要：为解决局部最大同步挤压变换算法识别的频率精度不足及频带能量发散的问题,提出一种改进算法并将之命名为改进局部最大同步挤压变换方法(improved local maximum synchrosqueezing transform,ILMSST)。该方法首先对瞬时频率(instantaneous freguency,IF)位置进行多次迭代,从而获得更高精度的瞬时频率位置。其次,搜索短时傅里叶系数模极大值的位置并上下平移该位置,得到初步估算的频带并将频带外的短时傅里叶系数归零。最后,搜索频率方向上短时傅里叶系数的局部最大值所对应的瞬时频率位置,根据这些位置对时频系数进行重排,进而得到细化的瞬时频带。通过2组数值算例、1个7层钢筋混凝土剪力墙振动台试验和1个时变拉索试验验证了所提新方法的有效性,研究结果表明:相比现有的局部最大同步挤压变换方法,改进算法不仅提高了瞬时频率的估算精度,而且改善了响应信号瞬时频带的时频聚集性。In order to get rid of the problems of inaccurate instantaneous frequency(IF) estimation and energy dissipation inside the local maximum synchrosqueezing transform algorithm,an improved method is proposed and named as local maximum synchrosqueezing transform(ILMSST).Firstly,multiple iterations are performed on the obtained IF positions to get more precise IF positions.Secondly,the IF positions where maximum values of STFT coefficients appear are searched and then moved up and down to pre-estimate IF bands.After that,the STFT coefficients outside the pre-determined IF bands are totally assigned to zero.Finally,the IF positions that correspond to local maximum values of STFT coefficients are found out and subsequently an operation of reassignment is performed on the obtained IF positions to get refined IF bands.To verify the effectiveness of the proposed method,two numerical cases and two tests on a seven-story reinforced concrete shear wall structure and a steel cable with time-varying tension forces are investigated.The results demonstrate that the proposed ILMSST method behaves better than current local maximum synchrosqueezing transform.Moreover,it not only enhances the accuracy of IF estimation but also improves time-frequency energy concentration.

关 键 词：时变 局部最大同步挤压变换 时频系数 瞬时频率 时频分析 

分 类 号：TN911.6[电子电信—通信与信息系统] TU311.3[电子电信—信息与通信工程]