Jian-shu CAO, Zhen-xing LUO, Bao-ping JI. Laser ultrasonic signal processing by differential algorithm in special pipeline thickness measurement[J]. Optics and precision engineering, 2017, 25(5): 1197-1205.
DOI:
Jian-shu CAO, Zhen-xing LUO, Bao-ping JI. Laser ultrasonic signal processing by differential algorithm in special pipeline thickness measurement[J]. Optics and precision engineering, 2017, 25(5): 1197-1205. DOI: 10.3788/OPE.20172505.1197.
Laser ultrasonic signal processing by differential algorithm in special pipeline thickness measurement
In view of the nonuniformity of pipe wall thickness of the special pipe under special environments such as high temperature
high pressure
radiation
and others
a method for laser ultrasonic measurement and thickness feature signals processing based on the differential algorithm was proposed. The laser ultrasonic method was adopted with pulse laser excitation and laser interference detection for the experimental measurement of broad-band laser ultrasonic signals of the test piece of pipe. Then the broad-band laser ultrasonic signals were de-noised by average algorithm in order to increase the signal to noise ratio of the original laser ultrasonic signals. Furthermore
the feature of the de-noised ultrasonic signals was extracted by differential algorithm
outputting the laser ultrasonic feature signals of pipe wall thickness. According to the sound velocity of pipe material and the laser ultrasonic transit time
the thickness values for the test piece of pipe wall were deduced. The error between the measured and actual thicknesses was less than 5%. The result shows that the processing method for thickness feature signals based on differential algorithm can provide favorable signal to noise ratio
accurate signal feature quantity and higher measurement accuracy
thus can be used for online real-time measurement of wall thickness of pipe and the thickness nonuniformity leaded by erosion and stress.
SONG SH P, LI P P. Convolution-mode-based ultrasonic echo separation technology and its application[J]. Chinese Journal of Scientific Instrument , 2009, 30(6):1175-1179.(in Chinese)
WU D H, YOU D H, LIU ZH L, et al ..Mechanism and experimental research on skin depth in AC magnetic flux leakage testing[J]. Chinese Journal of Scientific Instrument , 2014, 35(2):327-336.(in Chinese)
LUO Y K, LUO SH T, LUO F L, et al .. Realization and improvement of laser ultrasonic signal denoising based on empirical mode decomposition[J]. Opt. Precision Eng ., 2013, 21(2):479-487.(in Chinese)
WANG H CH, LI Y A. Determination of neighborhood size parameter of local projective algorithm for noise reduction[J]. Journal of System Simulation , 2007, 19(4):805-807.(in Chinese)
CHI D ZH, GANG T, SUN CH L. Ultrasonic clutter suppression method using adaptive filter[J]. Transactions of the China Welding Institution , 2015, 36(11):33-36.(in Chinese)
TONG Y, HUANG S L, ZHAO W, et al .. An EMAT denoising algorithm based on envelope filtering[J]. Chinese High Technology Letters , 2010(9):960-964.(in Chinese)
GONG ZH Q, ZHOU M W, GAO X Q, et al .. On the difference between empirical mode decomposition and wavelet decomposition in the nonlinear time series[J]. Acta Physica Sinica , 2005, 54(8):3947-3957.(in Chinese)
MA L, KANG J SH, MENG Y. et al .. Research on feature extraction of rolling bearing incipient fault based on Morlet wavelet transform[J]. Chinese Journal of Scientific Instrument , 2013, 34(4):920-926.(in Chinese)
ZHU H H, QIN H K, ZHANG M, et al .. Peak detection algorithm in the demodulation for the fiber Bragg grating sensor system[J]. Chinese Journal of Lasers , 2008, 35(6):893-897.(in Chinese)
TAO K, ZHU J J. A hybrid indicator for determining the best decomposition scale of wavelet denoising[J]. Acta Geodaetica et Cartographica Sinica , 2012, 41(5):749-755.(in Chinese)
WU G W, WANG CH M, BAO J D, et al .. A wavelet threshold de-noising algorithm based on adaptive threshold function[J]. Journal of Electronics & Information Technology , 2014, 36(6):1340-1347.(in Chinese)
WANG F N, LIANG D, TANG J, et al .. Multiscale edge detection based on wavelet modulus maxima[J]. Chinese Journal of Scientific Instrument , 2006 (z3):2147-2149.(in Chinese)
QIN X D, WANG T Y, LIU X R, et al .. Research on differential algorithm and its application in magnetic flux leakage signal processing[J]. Iron and Steel , 2004, 39(2):67-70.(in Chinese)
YANG ZH ZH, ZHOU J L, YAN X Y, et al .. Image enhancement based on fractional differentials[J]. Journal of Computer-aided Design & Computer Graphics , 2008, 20(3):343-348.(in Chinese)
ZHANG D, TASHPOLAT·T, ZHANG F, et al .. Application of fractional differential in preprocessing hyperspectral data of saline soil[J]. Transactions of the Chinese Society of Agricultural Engineering , 2014, 30(24):151-160.(in Chinese)