Patent ID: 8490433

Claim:
A method of applying ultrasonic acoustic energy to a glass melt by monitoring a glass melt temperature T Y and transferring ultrasonic acoustic energy from an ultrasonic transducer to the glass melt at a controller power P C and a controller frequency v C through an ultrasonic probe positioned in the glass melt, wherein: the controller power P C is controlled in response to at least (i) the monitored glass melt temperature T Y and (ii) a reference glass melt temperature T R ; the controller frequency v C is controlled in response to at least (i) one or more input parameters from a temperature-viscosity curve characterizing the glass melt, (ii) one or more input parameters from one or more temperature dependent impedance response models of the glass melt, and (iii) ΔZ, where ΔZ represents a degree to which an impedance condition Z Y of the ultrasonic probe differs from a reference impedance Z R when the ultrasonic probe is positioned in the glass melt; the input parameters are generated based on the identified resonance trough and are used for coarse control of the controller frequency v C ; ΔZ represents a power factor of the ultrasonic probe in the glass melt and is used for fine control of the controller frequency v C ; and the coarse control of the controller frequency v C is coarse relative to the fine control of the controller frequency v C and the fine-control of the controller frequency v C is fine relative to the coarse control of the controller frequency v C .