Ultrasonic waveform

Tuziuti T, Yasui K, Lee J, Kozuka T, Towata A, Iida Y (2009) Influence of surface active solute on ultrasonic waveform distortion in liquid containing air bubbles. J Phys Chem A... 

Fig. 15. Ultrasonic waveforms observed for P(VDF/TrFE) copolymer at three different temperatures below, around, and above the ferroelectric phase transition point...

All ultrasonic waveform data, probe position and amplifier gain information was digitised and recorded on disk to enable further analysis without returning to the plant. 

Beyond the information of one or more B-scan images of a tumor, new techniques in ultrasound may provide additional information per investigation. For instance, in elastography, ultrasonic waveforms before and after a light-tissue compression can be compared by means of image registration to calculate characteristic values out of the registration vectors. Further analysis may then be conducted by a support vector machine to classify solid breast lesions with an Az value of0.9358 (Chen CJ et al. 2006 Moon et al. 2005). 

FIGURE 9. Basic ultrasonic waveforms, (a) Continuous wave (b) pulse. 

Another interesting physical consideration of ultrasonic wave propagation is related to amplitude reduction of an ultrasonic waveform. An amplitude decay curve is illustrated in Figure 12. Lower frequencies can propagate further into a material, since material absorption... 

The CamuS system consists of a number of components, both hardware and software, as shown in Figure 1. The hub of the system is the data acquisition unit, which collects and stores ultrasonic data in the form of RF waveforms. An accurate probe position monitor provides information on the location and orientation of the probe as it is scanned over the test object. Software tools have been developed to provide assistance to the user with preparing inspection procedures according to the requirements of prEN1714 with visualising the data, in relation to the test object with making measurements of any indications present and with classifying indications. 

Fig. 13.18. Heterodyne mixed signals from ultrasonic vibration around 9 MHz of the sample and the cantilever, with difference frequencies (a) 5 kHz, (b) 15 kHz. The upper traces are from conventional electronic mixing of the excitation waveforms, the lower signals are from the cantilever response, with mixing occurring mechanically at the tip-sample contact. The electronically mixed waveforms were rectangular, giving rise to the triangular beat waveforms (Kolosov and Briggs 1996).

To measure the P-wave velocity and attenuation illustrated by Biot-StolTs model an automated, PC-controlled logging system was developed which records and stores digital ultrasonic P-waveforms transmitted radially across marine sediment cores (Breitzke and Spieli 1993). These transmission measurements can be done at arbitrary small depth... 

Breitzke M., Grobe H., Kuhn G, Muller R, 1996. Full waveform ultrasonic transmission seismograms - a fast new method for the determination of physical and sedimentological parameters in marine sediment cores. Journal of Geophysical Research 101 22123-22141... 

Figure 34a shows schematic views of the CFRP sample, ultrasonic signals and the position of the transducer, while Fig. 34b shows the observed waveforms... 

At measunng point A where there is no Teflon sheet, the time-domain waveform reveals only one reflection from the bottom surface of the CFRP sample, and its power spectrum shows a decrease in the higher-frequency component above 20 MHz, as shown in Fig. 35a. The decrease is probably caused by ultrasonic scattering by the multilayered structure of CFRP cloth, since the half-wavelength at 20 MHz is about 75 pm, which is comparable to the thickness of CFRP cloth (70 pm). 

Next, at measuring pomt B where the edge of the Teflon sheet is located, the time-domain waveform shows only reflection from the Teflon sheet. The disappearance of the reflection from the bottom surface of the CFRP sample is assumed to be due to the existence of a low-density region in the neighborhood of the Teflon sheet edge, which reflects almost all the ultrasonic waves because of its lower acoustic impedance. 

Fig. 34a. Schematic views of ultrasonic reflections at three different points of CFRP specimen b Corresponding time-domain waveforms of reflections...

At the defect sizing stage, a digital data collection system based around a PDPll/23 computer and TEKTRONIX 7912 digitiser Is used to collect ultrasonic rf waveforms for subsequent analysis (Fig 3). Data can be stored locally on floppy disc or transferred directly to the PDPll/44. 

A particularly Important example of this Interactive capability occurs in the analysis of time-of-flight diffraction inspection data files. Following display of the set of ultrasonic rf waveforms stored in each file on the colour graphics unit, a screen cursor is used to select points on identified waveforms for display as time-delay ellipses on the appropriate nozzle profile. The intersection point of the arcs generated from the same point on several waveforms corresponds to the location of the defect extremity producing the observed signal. 

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