Thesis (M.S.)--University of Michigan, 1981.

Thesis (M.S.)--University of Michigan, 1955.

Thesis (M.Med.Sc.)--University of Hong Kong, 2004. / Also available in print.

Thesis (M.D.Sc) - University of Queensland, [2003] / 2 papers ; abstract for each. Includes bibliographies.

Universität Freiburg, Diss., 2005.

Thesis (Ph. D.)--Columbia University, 2004. / Includes bibliographical references (leaves 402-434).

In this study, an experimental investigation was performed to characterize the dynamic stall of pitching wings and provide confirmation of the existence of the arch-shaped vortex for moderate sweep wing. Dynamic stall is a complex flow, which happens because of a sudden change of incident angle during the pitching motion. The pitching motion of a wing can cause instability in the shear layer and generate the separation burst at certain angles. For a pitching wing, the dynamic stall vortex is characterized by the formation of an arch-shaped vortex to the evolution of a ring-shaped vortex. The leg of the arch-shaped vortex causes a negative pressure region on the airfoil surface and can, in fact, generate greater lift. However, in certain conditions, the detachment of the arch-shaped vortex from the airfoil surface can cause high pressure and vibration in the structures. The formation of the arch-shaped vortex and its evolution were systematically investigated using cutting-edge flow diagnostic techniques, and the physics of the dynamic stall is explained in addition to providing the confirmation of the theory developed based on Computational Fluid Dynamics. The study was done using Particle Image Velocimetry (PIV) and Pressure-Sensitive Paint for three sweep angle wings. The wings, with an aspect ratio of AR=4 and a NACA 0012 section assembled with round-tip, are considered for the current experimental study. The sweep angles = 0, 15, and 30 degrees were considered to compare the flow phenomena. The PIV results show the formation of a laminar separation bubble and its evolution to a dynamic stall vortex. The increase of sweep angle causes the formation of such vortices towards the wing tip. In the process of finding the footprint of the vortices and pressure distribution on the surface of the wings, a single-shot lifetime method using fast porous paint was used. The results show the existence of suction pressure and later grows towards the trailing edge of the wing due to the formation of a dynamic stall vortex. In addition, at Re=2x10^5 and reduced frequency k=0.2, a moderate sweep airfoil shows the apparent footprint of the arch-shaped vortex, which confirms the current theory.

This study proposes a nitinol-based thin-walled arch wedge support (AWS) and validated its performance in shock absorbing by using finite element analysis (FEA) method. Five human movements, two boundary conditions, and three thicknesses were implemented in FEA models to systematically reveal how those parameters and factors affect the response of the AWS. Due to the lack of data, the FEA models were meshed with elements of different sizes and used for simulations until the results converged. The simulation results showed that the thin-walled nitinol AWS with the selected thicknesses can withstand different human movements under both boundary conditions. In another word, the AWS will retain its original shape give the force conditions with no permanent deformation. Based on the initial numerical results, the AWS design can be further optimized before experimentation and testing. The potential of replacing the plastic AWS with additive manufactured nitinol AWS is verified from this study.

Therapeutic exercise has previously been shown to alter the static height of the medial longitudinal arch (MLA). It is still unknown, however, if these effects carry over into dynamic activities. PURPOSE: To determine if an 8-week foot strengthening exercise program increases static arch height and reduces vertical deformation of the MLA during mid-stance in running.METHODS: Thirty-four recreational runners (17 males, 17 females) have completed this ongoing study (age 24.06 ± 3.61 years, body mass 68.63 ± 12.95 kg, and height 173.34 ± 9.54 cm). To date, 22 subjects have been assigned to the control group (8 weeks of normal running) and 12 to the foot strengthening group (8 weeks of foot strengthening, along with normal running). Static arch height (SAH) and dynamic arch drop (DAD) were measured at baseline and following the 8-week intervention using Vicon motion analysis. Reflective markers were placed on the proximal and distal ends of the 1st and 5th metatarsals. These 4 markers were recorded in static double leg stance to estimate SAH, and in single leg mid-stance to give a measure of DAD during treadmill running at a self-selected pace. Ten-second trials were recorded at minutes 3 and 4 during running and DAD was evaluated for right and left feet by comparing arch height in mid-stance to the SAH. Following the intervention, data for SAH and DAD were compared across time points and statistical analysis performed to identify differences in the amount of change in SAH and DAD between groups. RESULTS: There was no difference noted in DAD between the groups as a whole, but the change in DAD from baseline to the end of week 8 was statistically significant for those in the foot strengthening group with an initial DAD of ≥ 3.80 mm (p < .028). There was also a statistically significant increase in SAH in the foot strengthening group compared to the control group (p = .013). CONCLUSIONS: These preliminary data suggest that the foot strengthening intervention was effective in increasing SAH compared to the control group. The intervention was most effective at decreasing DAD in those with the largest amount of DAD at baseline. At this time it is unknown whether this decrease in arch drop is associated with performance benefits or decreased injury risk in the recreational runner, and further research is needed to determine the clinical significance of these findings.

This thesis tests the hypothesis that the qualities of different forecasts of exchange rate volatility depend on the underlying exchange rate regime. By examining the British pound during and after its withdrawal from the European Monetary System (EMS), this analysis compares "backward-looking" historical forecasts of future volatility with the "forward-looking" forecast of volatility reflected in current option prices. Because option implied volatility contains the market's most current expectations about future prices, theory and much previous evidence suggests this should be the superior predictor of future volatility. In contrast to previous research by findings, this study concludes that option implied volatility is not superior. During the time when the pound was in the EMS, implied volatility provided reasonably good forecasts of future volatility. However, after the pound withdrew from the EMS, various statistical measures of historical volatility are found to have greater informational content and predictive power about future actual volatility than implied volatility. In particular, a time series estimate, specifically a GARCH(1,1) model, had the most informational content and predictive power about realized pound volatility, especially in the period following sterling's withdrawal from the EMS. / Master of Arts