An airfoil shape optimization problem with conflicting objectives is handled using two different multi-objective approaches. These are an a priori scalarization approach where the conflicting objectives are assigned weights and summed together to form a single objective, and the Pareto-optimal multi-objective approach. The optimization formulations for both approaches contain challenging numerical characteristics which include noise, multi-modality and undefined regions. Gradient-, surrogate- and population-based single objective optimization methods are applied to the `a priori' formulations. The gradient methods are modified to improve their performance on noisy problems as well as to handle undefined regions in the design space. The modifications are successful but the modified methods are outperformed by the surrogate methods and population based methods. Population-based techniques are used for the Pareto-optimal multi-objective approach. Two established optimization algorithms and two custom algorithms are implemented. The custom algorithms use fitted unrotated hyper ellipses and linear aggregating functions to search the design space for non-dominated designs. Various multi-objective formulations are posed to investigate different aspects of the airfoil design problem. The non-dominated designs found by the Pareto-optimal multi-objective optimization algorithms are then presented. / Dissertation (MEng)--University of Pretoria, 2011. / Mechanical and Aeronautical Engineering / unrestricted

<p>For internal flows, the detachment of the boundary layer is a major contributor to pressure loss. To improve efficiency, it is essential to characterize these regions to understand the location and magnitude. Particle Image Velocimetry (PIV) is applied to provide time-resolved measurements to achieve accurate results without perturbing the flow. This thesis covers the methodology for creating an adaptable optical measurement technique in a high frequency study of separated regions in transonic internal flows. Focus on the optimization of the laser optical array and image acquisition system yield improved Dynamic Spatial Range (DSR) and Dynamic Velocity Range (DVR). Further analysis is provided on the flow dynamics of the seed particle, with local seeding solutions provided for improved seeding density in high-speed flows for various geometries. Light scattering efficiency of the particle is also analyzed to completely define the desired particle size. Two pulse-burst Nd:YAG lasers and two high speed cameras are used in this study to achieve a frame straddling technique necessary to resolve high frequency flows. Comparison of the recording media to the DSR highlights performance costs and benefits between the two cameras. Uncertainty measurements are determined from the calculated setup and compared to correlation statistics-based uncertainty quantifications. Image processing and cross-correlation software are used to provide analysis on the flow characteristics for two separate studies with comparison to Computational Fluid Dynamic predictions.</p>

Submitted to the faculty of Indiana University in partial fulfillment of the requirements for the degree Master of Science in the department of Bioinformatics in School of Informatics of Indiana University 29 January, 2004 / Background: Toll and Toll-related proteins play an important role in antibacterial innate immunity and are widespread in insects, plants, and mammals. The completion of new genomes such as Anopheles gambiae has provided an avenue for a deeper understanding of Toll evolution. While most evolutionary analyses are performed on protein sequences, here, we present a unique phylogenetic analysis of Toll genes from the perspective of upstream regulatory regions so as to study the importance of evolutionary information inherited in such sequences. Results: In a comparative study, phylogeny on the protein products of Toll like genes showed consistency with earlier literature except for the single point of divergence between insects and mammals. On the other hand, the phylogeny based on upstream regulatory sequences (-3000 to +10) showed a broader distinction between the plants and the rest, though the tree was not well resolved probably due to poor alignment of these sequences. The phylogeny based on TFBs necessitated the development of a supervised statistical approach to determine their “evolutionary informativeness”. Employing the frequency of evolutionarily informative TFBs, a phylogeny was derived using pair-wise distances. It suggested a closer relationship between Anopheles and plants than to Drosophila and a significant homology among mammalian TLRs. Conclusions: A unique approach of using TFBs in studying evolution of Toll genes has been developed. Broadly, this approach showed results similar to the protein phylogeny. The inclusion of the evolutionary information from TFBs may be relevant to such analyses due to the selective pressure of conservation in upstream sequences.

High structural diversity amongst plant species in the arid winter rainfall region of southern Africa is common to other arid regions of the world. Details of the range and combinations of structural attributes in species, and within plant communities, are not widely known for southern African arid ecosystems. Hence little is known of how plant-form distributions vary within and between arid ecosystems. and of the environmental factors that may be responsible for any variations found. Nor is much information available on how phenological behaviour relates to the structural attributes of plant species. This study examined structural attributes of perennial plant species on the Worcester Veld Reserve, southwestern Cape. in relation to their distribution and phenology. Species were grouped on the basis of above ground structural and anatomical criteria. The distribution of species and plant-forms was assessed through a phytosociological survey along an environmental gradient in the area, and their phenology determined through qualitative and quantitative monitoring of species phenophases over a two year period. The results show that species of the predefined structural groups i) Co-occur throughout the area. but relative abundances vary from site to site and in relation to topography. aspect and the presence of Mirna-like mounds; ii) Phenological patterns for the flora overall are strongly seasonal, but the timing and periods of phenophases differ between, but are relatively uniform within, the defined structural plant groups. Since phenological patterns are indicative of resource-use patterns. these results indicate that the different plant-forms have different functional responses to the conditions of limited water availability and summer drought. This conceivably facilitates the co-existence of species in this water-limited environment. Habitat variability. which can be related to land-form patterns. is also implicated as a factor facilitating the co-existence of a diversity of species and plant-forms. Structural functional relationships known for arid region plants help to explain the relative uniformity of behaviour within plantform groups. and aid in understanding the ecological significance of distribution patterns of plant-forms in the arid landscape. The conclusion is reached that because of the close coupling between photosynthesis and water-use. the water storage potential and photosynthetic organ type are plant attributes which can serve as useful criteria by which arid region species can be grouped into ecologically meaningful categories or functional guilds. The formulation of a practical and meaningful functional classification is necessary to facilitate the understanding of complex vegetation patterns and processes within arid ecosystems. and allow for meaningful inter-ecosystem comparisons.

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As a pattern of growth, sprawl is often criticized for its extensive negative impacts. These impacts range from economic costs to health and environmental problems. Critics of sprawl have also emphasized the negative consequences of this type of growth for social neighborhood ties. The physical environment of sprawling areas, characterized by low population density, segregation of land-uses, and lack of public spaces does not provide spaces for social interaction. On the contrary, transit-oriented and mixed-use neighborhoods might encourage interaction among residents because individuals are more likely to walk from place to place which might increase opportunities for informal contact and gather. Although there is a large body of research that study the impacts of sprawl, there is little empirical research of the impacts of sprawl on social interactions among neighbors. The purpose of this study is to contribute to the understanding of sprawl impacts and to fill this gap in the current literature by exploring the relationship between urban sprawl and neighborhood social interactions at the metropolitan level. According to my results, while neither an overall index of sprawl, nor individual indicators are observed to have a statistical significant association with different dimensions of neighbor interaction; a statistical significant association was found between the use of public spaces and the type and frequency of neighbor interaction among participants in this research. As such, the use of public parks and plazas, public libraries, and in some cases community centers is positively associated with neighborhood social interaction. These results, obtained while statistically controlling for demographic characteristics, highlight the importance of public spaces on the behavior of participants.

Four regions of massive star formation in the Large Magellanic Cloud (LMC) were observed for water and methanol maser emission and radio continuum emission. A total of 42 radio detections were made including 27 new radio sources, four water masers, and eight compact HII regions. The lobes of a radio galaxy were resolved for the first time, and the host galaxy identified. Seven sources were associated with known massive young stellar objects (YSOs). A multi-wavelength analysis using both the infrared and radio spectrum was used to characterize the sources. Mid-infrared color-magnitude selection criteria for ultracompact HII (UCHII) regions in the LMC are presented, yielding 136 UCHII region candidates throughout that galaxy. New maser detections identified two previously unknown massive YSOs. No methanol masers were detected, consistent with previous studies and supporting the hypothesis that the LMC may be deficient in these molecules. These discoveries contribute to the history of star formation in the LMC, which will lead to a better understanding of star formation in the Milky Way and throughout the universe.