Can minority language proficiency pay: a study on the return on English-Spanish fluent bilingualism in South Florida

This thesis studies the economic return for fluent-bilingualism in South Florida among native-born whites using IPUMS (Integrated Public Use Microdata Series) data for Miami-Dade County (1990). Previous mainstream-oriented theories focus on the benefit in English acquisition for immigrants and their descendants, either denying or ignoring the possible benefit of minority language retention in addition to English acquisition. An alternative literature, on the other hand, suggests that minority language retention can be beneficial in at least three areas: 1) enhancing cognitive ability; 2) accessing community-level social capital; and 3) serving as human capital. This study assesses economic returns in employment and earnings, using logistic and OLS (Ordinary Least Square) regression respectively. The results, countering the mainstream-oriented theories, suggest that fluent bilingualism does have economic consequences. Rather than fully supporting the positive effects thesis, the patterns shown are much more complicated, contingent on an individual's ethnic membership and educational level. Theoretical and substantive implications are discussed and suggestions for future research are made.

Design Optimization of Nozzle Shapes for Maximum Uniformity of Exit Flow

The objective of this study is to identify the optimal designs of converging-diverging supersonic and hypersonic nozzles that perform at maximum uniformity of thermodynamic and flow-field properties with respect to their average values at the nozzle exit. Since this is a multi-objective design optimization problem, the design variables used are parameters defining the shape of the nozzle. This work presents how variation of such parameters can influence the nozzle exit flow non-uniformities. A Computational Fluid Dynamics (CFD) software package, ANSYS FLUENT, was used to simulate the compressible, viscous gas flow-field in forty nozzle shapes, including the heat transfer analysis. The results of two turbulence models, k-e and k-ω, were computed and compared. With the analysis results obtained, the Response Surface Methodology (RSM) was applied for the purpose of performing a multi-objective optimization. The optimization was performed with ModeFrontier software package using Kriging and Radial Basis Functions (RBF) response surfaces. Final Pareto optimal nozzle shapes were then analyzed with ANSYS FLUENT to confirm the accuracy of the optimization process.