A signal decomposition method based on repeated extraction of maximum energy component for offshore structures. (July 2020)

• Record Type: Journal Article
• Authors: Liu, Fushun; Gao, Shujian; Liu, Dianzi; Zhou, Hu
• Is Part Of: Marine structures. Volume 72(2020)
• Publication Date: 2020-07
• Subjects: Offshore structures -- Dynamic analysis -- Signal decomposition -- Maximum energy component; Naval architecture -- Periodicals; Offshore structures -- Periodicals; Architecture navale -- Périodiques; Structures offshore -- Périodiques; Naval architecture; Offshore structures; Periodicals; 620.4162
• DOI: 10.1016/j.marstruc.2020.102779
• Languages: English
• ISSNs: 0951-8339

Abstract

Abstract: Contrary to most signal decomposition methods that usually decompose an original signal into a series of components simultaneously, a novel approach based on repeated extraction of Maximum Energy Component (MEC) is proposed. The approach starts from determination of the MEC referring to the estimated Power Spectral Density (PSD) function, and then represents the MEC by employing an exponential function to fit the original signal. By defining a stopping criterion based on two adjacent estimated PSDs, each MEC can be accurately extracted with an improved performance throughout the entire signal decomposition. To verify the proposed method, a single degree-of-freedom system subject to harmonic loads has been examined. Numerical results show that the analytical response can not only be decomposed into four MECs corresponding to the excitation and the system, respectively, but also provide an accurate estimation of natural frequency and damping ratio of the system. Meanwhile, by observing results from the Ensemble Empirical Mode Decomposition (EEMD), Variational Mode Decomposition (VMD) and Prony based on state-space model (Prony-SS), an improved decomposition accuracy has been achieved from the proposed approach. Furthermore, experimental data from the Norwegian Deepwater Programme and two sets of field-test data from one fixed offshore platform and an offshore wind turbine have been used to demonstrate the correctness of the developed signal decomposition method. It is noted that divergence in results by Prony-SS can be observed when a very large model order is used, while the proposed method provides the better decomposition and reconstruction of signals. Highlights: A new signal decomposition method based on repeated extraction of maximum energy component is proposed. The advantage of this approach is that each component can be extracted with expected accuracy. A single degree-of-freedom system is employed to demonstrate the approach. Experimental data from the Norwegian Deepwater Programme is used to make comparisons with traditional methods. Field test data from one offshore platform and an offshore wind turbine are used to discuss potential applications.