Driving frequency optimization of a piezoelectric transducer and the power supply development.

Piezoelectric transducers are commonly operated at their resonance frequency. However, from a power dissipation standpoint, this is not the ideal driving frequency. In this paper, an optimized driving frequency in between the resonance and antiresonance frequencies is proposed for the piezo-transducer.

Oscillation mode conversion and energy confinement of acoustically agitated bubbles.

The acoustically agitated bubble oscillation in liquids that is considered to be related to the half-subharmonic acoustic bubble oscillations is discussed in terms of parametric decay instability. At the frequency of about 40 kHz, the half-subharmonic bubble oscillation mode should be a surface bubble oscillation that does not easily emit acoustic waves into water and confines acoustic energy from longitudinal waves. The half-subharmonic bubble oscillation is the dominant mode that leads to parametric decay instability of bubble oscillations.