Adaptive basis selection for multi texture segmentation by M-band wavelet packet frames

2002 ◽  
Author(s):  
M. Acharyya ◽  
M.K. Kundu
Keyword(s):  
Wavelet Packet ◽  
Texture Segmentation ◽  
Selection For ◽  
Adaptive Basis Selection

Vibration-Based Damage Detection of Composite Wingbox Structures Using Improved Hilbert-Huang Transform

2006 ◽  
Vol 324-325 ◽  
pp. 539-542 ◽  
Author(s):  
Huan Guo Chen ◽  
Yun Ju Yan ◽  
Jie Sheng Jiang
Keyword(s):  
Structural Damage ◽  
Wavelet Packet ◽  
Dynamic Responses ◽  
Structural Dynamic ◽  
Hilbert Huang Transform ◽  
Mode Function ◽  
Index Vector ◽  
Selection For ◽  
Instantaneous Energy ◽  
Composite Wing

A vibration-based approach to detect crack damage in a cantilever composite wingbox is studied using the improved Hilbert-Huang Transform (HHT). The improved HHT is composed of HHT with Wavelet Packet Transform (WPT) and a simple but effective method for intrinsic mode function (IMF) selection. For different damage status, in order to obtain structural dynamic responses, which imply plentiful damage information, the composite wing boxes were excited by a contrived square wave signal. Then, the dynamic responses of intact wingbox and damaged wingbox are disposed using improved HHT. Finally, a feature index vector of structural damage, i.e. the ariation quantity of instantaneous energy, is constructed. The obtained results show that the proposed damage feature index vector is more sensitive to small damage than those in traditional signal processing.

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