Characterization of Metallic and Dielectric Surfaces Using Ellipsometry - Alexander A. Fisher '10
Abstract: A home-built ellipsometer was used to measure the complex refractive index of three surfaces. The surfaces were a dielectric glass slide, a 377 nm Al film, and a 200 nm Au film. Three runs of the glass slide gave indices of 1.498, 1.493, and 1.4 – 0.045i. Compared to expected index of 1.515, this gave percent errors of 1.1%, 1.5% and 4.1 %, respectively. Similarly, three runs of the Al film gave 1.130 + 1.573i, 1.207 + 2.439i, and 1.206 + 2.469i with percent errors of 18.4%, 12.8% and 12.9% for the real part and 120.6%, 131.9% and 132.3% for the imaginary part. The Au film gave 0.260 – 3.428i, 0.263 – 2.774i and 0.482 – 2.362i with percent errors of 34.2%, 35.5% and 148.7% for the real part and 10.7%, 10.4% and 23.5% for the imaginary part.
For more information, contact Dr. Catherine Jahncke
Efficiency of PEM Fuel Cells - Chad Miller '10
Abstract: This experiment tried to model a PEM FC as a simple battery in an attempt to characterize its efficiency as a result of certain parameters. It was found that the EMF of a FC behaves like a battery when placed in series, but the internal resistance does not. A thinner membrane results in slightly lower EMFs (roughly 15%) and the internal resistance goes up as expected. The experiment found the efficiency of the PEM FCs decreases as the temperature increases, as the literature predicts. The efficiencies found in this experiment (40% to 60%) for the simple battery model of a FC would be more precise if a more complex model was used that predicted the results seen in the data.
For more information, contact Dr. Daniel Koon
Vibration and Salt Concentration Affecting the Behavior and Viscosity of Cornstarch, a non-Newtonian Fluid - David Tersegno '10
Abstract: An overview of non-Newtonian fluids models is given, with examples. We take cornstarch samples and vibrate them on a mechanical piston at a frequency of f = 20 Hz and describe the surface structures and movements that occur. We then measure the dynamic viscosity of cornstarch solutions with varying levels of salt concentration. In small quantities, adding salt was found to decrease the viscosity of the cornstarch. As the concentration approached 10% of the mixture by weight, there was a net increase in viscosity.
For more information, contact Dr. Brian Watson