Front wall echo

MHz to 40 MHz. This was highly focused so that the beam width was 0.001 in. (0.025 mm). The return echoes were digitized at 500 MHz using a Tektronix 7912 digitizing unit. This unit can record 512 data points, or 1.02 xsec of data, which means that some of the BWE (Back Wall Echo) would be eliminated for thicker bonds this was not a problem since only EWE (Front Wall Echo), BLEl (1st Bondline Echo), and BLE2 (2nd Bondline Echo) was required forevaluation purposes. Because of disk storage restrictions, data was taken in 2.5 mm increments. This time, differences between the two surface preparation types were observed in the frequency area ratio features. The feature used was... 

The ultrasonic pulse echo (UPE) method is used to measure the wall thickness of vessels. UPE can be adapted to distinguish chemical munitions from conventional types and to determine the filling level of shells. Differentiation between munition types is based on the fact that, besides the normal reflexion signal from the front wall, the detection of a rear-wall or burster-tube echo clearly indicates the presence of a liquid as filling, whereas with conventional munitions the original pulse is reflected only from the front wall. 

This area is limited by the echo of the entrance window in front, the noise of the electronic equipment and the accuracy of the digitizer or the distance between the container walls. 

In 2013 the full scale measurements of scour holes formed due to bow thrusters and main propellers action in front of the quay wall were performed in Port of Rotterdam. After each departure the bathymetry near the quay was measured using a multi-beam echo sounder. 

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