Sample Thesis Paper
The longitudinal waveform of the ultrasonic beam from the focused transducer was determined using a needle type hydrophone as a receiver of the signal and water as the medium. The acoustic wave forces the water particles to oscillate back and forth in direction of the traveling wave. Thus, successive zones of compressions and rarefactions appear as regions of high and low amplitudes, as shown in Figure 2. The overall acoustic waveform in the water takes a form of series of compressions and rarefactions that ends at the last field of high pressure (compression) and gradually drops to zero.
On the lateral direction, the acoustic waveform shows also oscillations in the medium content, Figures 3 and 4. These oscillations seem to be more complex in the near field than in the far field whereby just small oscillations appear in the sides. The lateral waveform in both shows how the acoustic wave spreads. Since the maximum sound pressure is always found along the axis of symmetry of the transducer  then the lateral waveform at 106 mm indicate that there might be some error in the assigned axis of symmetry of the transducer, where it shows that the strongest reflection is slightly off the symmetry by 2 mm.
The oscilloscope measured the times between the transmitted and the received signals. The speed of ultrasonic wave was found to be, 1467.89 m/sec, according to the lab %%% the speed of sound in water at a temperature of 22 Co is %%%. The relative error in determining the velocity is %%%.