Nonlinear modeling of wavelet coefficients around edges

2004 ◽  
Author(s):  
H.F. Ates ◽  
M.T. Orchard
Keyword(s):  
Nonlinear Modeling ◽  
Wavelet Coefficients

scholarly journals Bayesian modeling and significant features exploration in wavelet power spectra

2007 ◽  
Vol 14 (1) ◽  
pp. 79-88 ◽  
Author(s):  
D. V. Divine ◽  
F. Godtliebsen
Keyword(s):  
Data Analysis ◽  
Traditional Approach ◽  
Statistical Significance ◽  
Power Spectra ◽  
Simulated Data ◽  
Scale Space ◽  
Independent Random Variables ◽  
Discrete Wavelet ◽  
Wavelet Coefficients ◽  
Testing Procedures

Abstract. This study proposes and justifies a Bayesian approach to modeling wavelet coefficients and finding statistically significant features in wavelet power spectra. The approach utilizes ideas elaborated in scale-space smoothing methods and wavelet data analysis. We treat each scale of the discrete wavelet decomposition as a sequence of independent random variables and then apply Bayes' rule for constructing the posterior distribution of the smoothed wavelet coefficients. Samples drawn from the posterior are subsequently used for finding the estimate of the true wavelet spectrum at each scale. The method offers two different significance testing procedures for wavelet spectra. A traditional approach assesses the statistical significance against a red noise background. The second procedure tests for homoscedasticity of the wavelet power assessing whether the spectrum derivative significantly differs from zero at each particular point of the spectrum. Case studies with simulated data and climatic time-series prove the method to be a potentially useful tool in data analysis.

Nonlinear modeling and simulation of flywheel energy storage rotor system with looseness and rub-impact coupling hitch

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Zhu Youfeng ◽  
Liu Xinhua ◽  
Wang Qiang ◽  
Wang Zibo ◽  
Zang Hongyu
Keyword(s):  
Energy Storage ◽  
Differential Equations ◽  
Nonlinear Modeling ◽  
Storage System ◽  
Energy Storage System ◽  
Rotor System ◽  
Flywheel Energy Storage ◽  
Flywheel Energy Storage System ◽  
New Energy ◽  
Single Disk

Abstract Flywheel energy storage system as a new energy source is widely studied. This paper establishes a dynamic model of a single disk looseness and rub-impact coupling hitch flywheel energy storage rotor system firstly. Then dynamic differential equations of the system under the condition of nonlinear oil film force of the sliding bearing are given. Runge–Kutta method is used to solve the simplified dimensionless differential equations. The effect of variable parameters such as disk eccentricity, stator stiffness and bearing support mass on the system are analyzed. With the increase of eccentricity, the range of period-three motion is significantly reduced and the range of chaotic motion begins to appear in the bifurcation diagram. Meanwhile, stiffness of the stator and mass of the bearing support have a significant influence on the flywheel energy storage rotor system.

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