Elaboration of some signal processing algorithms in ultrasonic techniques: application to materials NDT

Drai, Redouane; Sellidj, F.; Khelil, Mohamed; Benchaala, A.

doi:10.1016/s0041-624x(99)00082-7

Cited by 49 publications

(20 citation statements)

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“…The estimation is based on the use of a DSP, which provided the statistics of recorded RF signals and their envelope function. The derivation and description of fast envelope detection techniques and envelope signal processing algorithms are beyond the scope of this article and can be found elsewhere [40,41].…”

Section: Measurement Detailsmentioning

confidence: 99%

Directing ultrasound at the cemento-enamel junction (CEJ) of human teeth: I. Asymmetry of ultrasonic path lengths

John

2005

Ultrasonics

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Section: Measurement Detailsmentioning

confidence: 99%

Directing ultrasound at the cemento-enamel junction (CEJ) of human teeth: I. Asymmetry of ultrasonic path lengths

John

2005

Ultrasonics

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“…To more reliably identify the locations of the echoes, we calculated the roundtrip times from the Hilbert transform of the signal and the calculated magnitude of the analytic of the signal, as briefly described in 9 . This technique, with various application-specific modifications, is frequently used in nondestructive ultrasonic testing 10 .…”

Section: Measuring Elastic Modulus and Acoustic Velocitymentioning

confidence: 99%

Laser alteration of the mechanical properties of photostructurable glass-ceramic

2008

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Photostructurable glass-ceramics (PSGCs) present an attractive alternative to silicon as substrates for microfabrication. Moving a laser beam with a focal volume a few microns across and a few tens of microns high through a transparent PSGC induces a cascade of reactions that results in selective crystallization in the laser-exposed regions. The process offers excellent 3-D shaping control. Crystal formation alters many material properties, including opacity, index of refraction, etch rates, density, stiffness, and strength. Presented here are the results of bulk mechanical measurements of the mass density and the velocity of sound in several phases of Foturan, a commercially available PSGC. The measurements are nondestructive and easily repeatable at many stages of processing. From the velocity and the mass density, we calculated the elastic modulus for each Foturan phase. The measured samples included native, amorphous Foturan; exposed Foturan that was not thermally treated; and exposed, thermally treated Foturan. Results show that Foturan becomes somewhat stiffer with higher crystal content; the elastic modulus of Foturan rises from about 78 GPa in the original amorphous glass state to about 88 GPa in a crystal-rich, exposed, baked state. The speed of sound in Foturan rises from about 5.8 km/s to 6.1 km/s.

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“…Some success using neural networks has been reported with the use of the Hopfield [9] method and a back-propagation algorithm [10]. R. Drai [11] proposed a new signal processing technique known as "split spectrum processing". It improves the signal-to-noise ratio.…”

Section: Introductionmentioning

confidence: 99%

<title>Development of an automated ultrasonic testing system</title>

Shuxiang

Wong

2005

SPIE Proceedings

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Non-Destructive Testing is necessary in areas where defects in structures emerge over time due to wear and tear and structural integrity is necessary to maintain its usability. However, manual testing results in many limitations: high training cost, long training procedure, and worse, the inconsistent test results. A prime objective of this project is to develop an automatic Non-Destructive testing system for a shaft of the wheel axle of a railway carriage. Various methods, such as the neural network, pattern recognition methods and knowledge-based system are used for the artificial intelligence problem. In this paper, a statistical pattern recognition approach, Classification Tree is applied. Before feature selection, a thorough study on the ultrasonic signals produced was carried out. Based on the analysis of the ultrasonic signals, three signal processing methods were developed to enhance the ultrasonic signals: CrossCorrelation, Zero-Phase filter and Averaging. The target of this step is to reduce the noise and make the signal character more distinguishable. Four features: 1. The Auto Regressive Model Coefficients. 2. Standard Deviation. 3. Pearson Correlation 4. Dispersion Uniformity Degree are selected. And then a Classification Tree is created and applied to recognize the peak positions and amplitudes. Searching local maximum is carried out before feature computing. This procedure reduces much computation time in the real-time testing. Based on this algorithm, a software package called SOFRA was developed to recognize the peaks, calibrate automatically and test a simulated shaft automatically. The automatic calibration procedure and the automatic shaft testing procedure are developed.

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Elaboration of some signal processing algorithms in ultrasonic techniques: application to materials NDT

Cited by 49 publications

References 1 publication

Directing ultrasound at the cemento-enamel junction (CEJ) of human teeth: I. Asymmetry of ultrasonic path lengths

Directing ultrasound at the cemento-enamel junction (CEJ) of human teeth: I. Asymmetry of ultrasonic path lengths

Laser alteration of the mechanical properties of photostructurable glass-ceramic

<title>Development of an automated ultrasonic testing system</title>

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