On the use of the polynomial annihilation edge detection for locating cracks in beam-like structures

2013 ◽  
Vol 114-115 ◽  
pp. 72-83 ◽  
Author(s):  
Cecilia Surace ◽  
Richard Archibald ◽  
Rishu Saxena
Keyword(s):  
Edge Detection ◽  
Polynomial Annihilation

Detection and Localisation of Structural Damage Based on the Polynomial Annihilation Edge Detection: An Experimental Verification

2013 ◽  
Vol 569-570 ◽  
pp. 1273-1280 ◽  
Author(s):  
Cecilia Surace ◽  
Massimiliano Mattone ◽  
Marco Gherlone
Keyword(s):  
Edge Detection ◽  
Damage Detection ◽  
Structural Damage ◽  
High Spatial Resolution ◽  
Mode Shapes ◽  
Laser Vibrometer ◽  
Numerical Assessment ◽  
Polynomial Annihilation ◽  
Vibration Tests ◽  
Derivatives Of

The present paper describes an experimental validation of a new structural damage detection method based on the Polynomial Annihilation Edge Detection (PAED) technique. It is well known that concentrated damage such as a crack, causes a discontinuity in the rotations and consequently in the first derivatives of the mode shapes. On this basis, the PAED, a numerical method for detecting discontinuities in smooth piecewise functions and their derivatives, can be applied to the problem of damage detection and localisation in beam-like structures for which only post-damage mode shapes are available. As described in this paper, in order to verify this approach experimentally (a numerical assessment having already been documented in previous papers), vibration tests on a cantilever steel beam with a saw-cut have been performed and the Operational Deflection Shapes (ODS) determined. As the approach requires a reasonably high spatial resolution of the ODS, a scanning laser vibrometer, capable of acquiring data rapidly at a very large number of observation points, was used.

Structural Damage Detection Based on an Improved Edge-Detection Technique

2013 ◽  
Author(s):  
Peng Chen ◽  
Guangda Hu ◽  
Soheil Nazarian ◽  
Guirong Yan
Keyword(s):  
Edge Detection ◽  
Damage Detection ◽  
Structural Damage ◽  
Computational Effort ◽  
Mode Shapes ◽  
Jump Discontinuities ◽  
Bridge Model ◽  
Polynomial Annihilation ◽  
Different Types ◽  
Edge Detection Method

To localize small damage from mode shapes, the polynomial annihilation edge detection method has been proposed and demonstrated its effectiveness on different types of structural components [7]. However, much computational effort involved in this approach lowers the damage detection speed. To alleviate this difficulty, in this paper, we improve the approach by first using the divided difference approach to identify the region(s) in which jump discontinuities are located, and then only applying the polynomial annihilation method to points in the identified region. In this way, the computational burden of this approach is significantly relieved, while the accuracy is still maintained. The improved approach has been validated by numerical simulations on a cable-stayed bridge model. This approach only requires post-damage mode shapes.

Difference mode EXELFS with parallel-detection EELS

1992 ◽  
Vol 50 (2) ◽  
pp. 1262-1263
Author(s):  
Michael K. Kundmann ◽  
Ondrej L. Krivanek
Keyword(s):  
Edge Detection ◽  
Important Distinction ◽  
Edge Structure ◽  
Parallel Detection ◽  
Gain Variation ◽  
Ideal Solutions ◽  
Detector Cell ◽  
The Difference ◽  
Elemental Detection ◽  
Partial Correction

Parallel detection has greatly improved the elemental detection sensitivities attainable with EELS. An important element of this advance has been the development of differencing techniques which circumvent limitations imposed by the channel-to-channel gain variation of parallel detectors. The gain variation problem is particularly severe for detection of the subtle post-threshold structure comprising the EXELFS signal. Although correction techniques such as gain averaging or normalization can yield useful EXELFS signals, these are not ideal solutions. The former is a partial throwback to serial detection and the latter can only achieve partial correction because of detector cell inhomogeneities. We consider here the feasibility of using the difference method to efficiently and accurately measure the EXELFS signal.An important distinction between the edge-detection and EXELFS cases lies in the energy-space periodicities which comprise the two signals. Edge detection involves the near-edge structure and its well-defined, shortperiod (5-10 eV) oscillations. On the other hand, EXELFS has continuously changing long-period oscillations (∼10-100 eV).

A Dividing Ratio Changeable Digital PLL Based on Phase State Memory and Double Clock-Edge Detection

2008 ◽  
Vol 128 (7) ◽  
pp. 1185-1190 ◽  
Author(s):  
Kuniaki Fujimoto ◽  
Hirofumi Sasaki ◽  
Mitsutoshi Yahara
Keyword(s):  
Edge Detection ◽  
Phase State
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