An Improved Hilbert-Huang Transform for Non-linear and Time-Variant Signals

Author(s):  
Cesare Alippi ◽  
Wen Qi ◽  
Manuel Roveri
2015 ◽  
Vol 7 (4) ◽  
pp. 168781401558212 ◽  
Author(s):  
Arturo González ◽  
Hussein Aied

2021 ◽  
Author(s):  
Subham Kashyap ◽  
Nilanjan Saha ◽  
K. A. Abhinav

Abstract The present work studies the performance of an offshore wind turbine system in an earthquake coupled with wave and wind loading. The NREL 5 MW offshore wind turbine, supported on the OC4 jacket [14], has been analysed within a finite element framework. A coupled model of hydrodynamics and soil-structure interaction has been implemented. The structure-foundation system is analysed under earthquakes recorded close to offshore waters and at sites with shear-wave velocities, classified under Site-Class D or Site-Class E as per API RP: 2EQ [8]. The soil conditions emulate characteristics of a prospective offshore wind turbine site along the west coast of India, which falls within the Site-Class D classification mentioned above. The geotechnical modelling is done as per the soil curves prescribed by the non-linear Winkler springs along the pile’s length. The complete analysis has been processed in a finite-element framework through the commercial program USFOS [16]. The Hilbert-Huang transform [29] of the tower-responses suggests the increased vulnerability to the resonance phenomenon with 1P and 3P loading. It also suggests an involvement of higher modes in the tower-response. The change in the frequency of the structure-foundation system during and post-earthquake has also been studied.


2019 ◽  
Vol 344 ◽  
pp. 970-980 ◽  
Author(s):  
Yadong Zhang ◽  
Xuliang Yang ◽  
Fenglong Zhu ◽  
Yanjiao Li ◽  
Chenlong Duan ◽  
...  

Author(s):  
Rodolfo T. Gonc¸alves ◽  
Guilherme R. Franzini ◽  
Guilherme F. Rosetti ◽  
Andre´ L. C. Fujarra ◽  
Kazuo Nishimoto

Vortex-Induced Motion (VIM) is a highly non-linear dynamic phenomenon. Usual spectral analysis methods, using the Fourier transform, rely on the hypotheses of linear and stationary dynamics. A method to treat non-stationary signals that emerge from non-linear systems is denoted Hilbert-Huang transform method (HHT). The development of an analysis methodology to study the VIM of a MPSO (Monocolumn Production, Storage and Offloading System) using HHT was presented. The purposes of the analysis methodology are to improve the statistics characteristics of VIM. The results showed to be comparable to results obtained from the traditional analysis (mean of the 10% highest peaks) principally for the motions in the transverse direction, although the difference between the results from the traditional analysis for the motions in the in-line direction showed a difference of around 25%. The results from the HHT analysis are more reliable than the traditional ones, owing to the larger number of points to calculate the statistics characteristics. These results should be used to design the risers and mooring lines, as well as to obtain parameters of the VIM to calibrate numerical predictions.


Author(s):  
Maximiliano Bueno-López ◽  
Johinner Mauricio Sanabria Villamizar

The smart grid concept is being applied more and more frequently and this is due to the need to integrate all the components that are part of power systems today, starting from generation units, storage systems, communications and connected loads. Non-linear and non-stationary signals have been obtained in this type of systems, which have high penetration of non-conventional energy sources (NCSRE) and non-linear loads. The power quality criterion has had to be adapted to the new conditions of the electrical systems and this has led to the need to search for new analysis methodologies for the acquired signals. In this article we present a review on non-linear and non-stationary signal analysis methods in electrical systems with high NCSRE penetration. To this end we explore the application of the Hilbert-Huang Transform (HHT), Wavelet Transform (WT) and Wigner-Ville Distribution (WVD), exposing each of the advantages and disadvantages of these methods. To validate the methodology, we have selected some synthetic signals that adequately describe the typical behaviors in these systems.


2011 ◽  
Vol 1 (32) ◽  
pp. 66
Author(s):  
Theo Garcia Rolim de Moura ◽  
Claudio Freitas Neves ◽  
José Claudio De Faria Telles

The Hilbert-Huang Transform (HHT) is extended to the time series analysis of wave orbital velocities resulting from the superposition of waves propagating in different directions. On a theoretical basis, it is shown that an apparently chaotic velocity signal may result from the interaction of three or more waves, each one with its own period and direction of propagation. Such result is compatible with records of PUV instruments. The comparison between bivariate HHT with Fourier directional analysis shows several advantages of the former, such as identification of wave groups and non-linear interaction components.


1967 ◽  
Vol 28 ◽  
pp. 105-176
Author(s):  
Robert F. Christy

(Ed. note: The custom in these Symposia has been to have a summary-introductory presentation which lasts about 1 to 1.5 hours, during which discussion from the floor is minor and usually directed at technical clarification. The remainder of the session is then devoted to discussion of the whole subject, oriented around the summary-introduction. The preceding session, I-A, at Nice, followed this pattern. Christy suggested that we might experiment in his presentation with a much more informal approach, allowing considerable discussion of the points raised in the summary-introduction during its presentation, with perhaps the entire morning spent in this way, reserving the afternoon session for discussion only. At Varenna, in the Fourth Symposium, several of the summaryintroductory papers presented from the astronomical viewpoint had been so full of concepts unfamiliar to a number of the aerodynamicists-physicists present, that a major part of the following discussion session had been devoted to simply clarifying concepts and then repeating a considerable amount of what had been summarized. So, always looking for alternatives which help to increase the understanding between the different disciplines by introducing clarification of concept as expeditiously as possible, we tried Christy's suggestion. Thus you will find the pattern of the following different from that in session I-A. I am much indebted to Christy for extensive collaboration in editing the resulting combined presentation and discussion. As always, however, I have taken upon myself the responsibility for the final editing, and so all shortcomings are on my head.)


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