What is it about?
A Dynamic Time Warping algorithm to compare the ultrasonic signals going through a material when it changes, so we can estimate the velocity of the waves travelling through in a consistent manner.
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Why is it important?
First some context, we record ultrasonic waves using piezoelectric transducers of a central frequency ranging from 0.5 to 1.0 MHz. A transmitter generates body waves (P or S) on one end of the sample and a receiver records it at the opposite end of it. In Non-destructive Testing (NDT) and in Rock Physics (RP) we are interested in measuring ultrasonic wave velocities (speeds) through the materials we study; may they be metals, concrete, rocks, etc. Usually, these materials experience changes over time (e.g. saturation, dissolution, cracking, among others) and we are interested in detecting the effects of these changes in ultrasonic wave velocities.
Perspectives
We define our guidelines to decide on the arrival-time feature of ultrasonic waves for NDT and Rock Physics measurements. We provide free software for carrying this task out. This work could benefit either seasoned experimentalists or people wanting to perform this kind of ultrasonic tests that are not well acquainted with signal processing techniques. We explain our picking criteria, but leave the selection of times open to the experimenter.
Dr. Evert Leonardo Durán
University of Auckland
Read the Original
This page is a summary of: A robust methodology for time picking and error analysis of ultrasonic waveforms and rock densities in the laboratory, Geophysics, March 2019, Society of Exploration Geophysicists,
DOI: 10.1190/geo2018-0331.1.
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