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Smart Structures and Systems Volume 22, Number 3, September 2018 , pages 359-368 DOI: https://doi.org/10.12989/sss.2018.22.3.359 |
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Instantaneous frequency extraction in time-varying structures using a maximum gradient method |
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Jing-liang Liu, Xiaojun Wei, Ren-Hui Qiu, Jin-Yang Zheng, Yan-Jie Zhuand Irwanda Laory
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Abstract | ||
A method is proposed for the identification of instantaneous frequencies (IFs) in time-varying structures. The proposed method combines a maximum gradient algorithm and a smoothing operation. The maximum gradient algorithm is designed to extract the wavelet ridges of response signals. The smoothing operation, based on a polynomial curve fitting algorithm and a threshold method, is employed to reduce the effects of random noises. To verify the effectiveness and accuracy of the proposed method, a numerical example of a signal with two frequency modulated components is investigated and an experimental test on a steel cable with time-varying tensions is also conducted. The results demonstrate that the proposed method can extract IFs from the noisy multi-component signals and practical response signals successfully. In addition, the proposed method can provide a better IF identification results than the standard synchrosqueezing wavelet transform. | ||
Key Words | ||
instantaneous frequency; time-varying structures; maximum gradient; wavelet transform; wavelet ridge | ||
Address | ||
Jing-liang Liu, Ren-Hui Qiu and Jin-Yang Zheng: College of Transportation and Civil Engineering, Fujian Agriculture and Forestry University, Fuzhou, China Xiaojun Wei,Yan-Jie Zhu and Irwanda Laory: School of Engineering, University of Warwick, Coventry, United Kingdom | ||