Francis P. Dawson

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A partial differential equation (PDE) model for the dynamics of a thin piezoelectric plate in an electric field is presented. This PDE model is discretized via the finite volume method (FVM), resulting in a system of coupled ordinary differential equations. A static analysis and an eigenfrequency analysis are done with results compared with those provided(More)
Piezoelectric devices, such as piezoelectric traveling- wave rotary ultrasonic motors, have composite piezoelectric structures. A composite piezoelectric structure consists of a combination of two or more bonded materials, at least one of which is a piezoelectric transducer. Piezoelectric structures have mainly been numerically modeled using the finite(More)
Piezoelectric traveling wave rotary ultrasonic motors are motors that generate torque by using the friction force between a piezoelectric composite ring (or disk-shaped stator) and a metallic ring (or disk-shaped rotor) when a traveling wave is excited in the stator. The motor speed is proportional to the amplitude of the traveling wave and, in order to(More)
Thermoelectric modules are an important alternative to heat engines in the harvesting of waste heat. Electrical-thermal analogs are often employed when studying heat conduction and this approach can be extended to develop a model for thermoelectric effects. In this article, the coupled thermoelectric partial differential equations are discretized using the(More)
Piezoelectric devices, such as piezoelectric traveling wave rotary ultrasonic motors, have composite piezoelectric structures. A composite piezoelectric structure consists of a combination of two or more bonded materials, where at least one of them is a piezoelectric transducer. Numerical modeling of piezoelectric structures has been done in the past mainly(More)
A. 4-bit fourth-order delta-sigma modulator with a widely programmable center frequency is presented. Novel methods for quantizing and implementing the digitally programmable modulator coefficients enable performance comparable to state-of-the-art discrete-time fixed-frequency modulators at any center frequency from dc to 0.31 fs in steps of 0.0052/s. The(More)
High-temperature high-pressure arc lamps are used to thermally process semiconductor wafers. An accurate dynamic model that links the radiation output to the current input would facilitate the design of a power circuit that optimizes energy transfer to the arc. In this paper, a dynamic arc model is derived using averaging of the energy balance equation over(More)
Ultracapacitors are energy storage devices that can be connected in parallel with batteries to create a hybrid power system. This hybrid configuration provides a higher power density than a single battery and helps extend the life of the batteries. An important issue is the voltage regulation of a battery-supplied dc bus subjected to a long high-power(More)