Northern bobwhites (Colinus virginianus) are a valued game species that have seen massive population declines in the last few decades. This decline has been attributed to many factors including predation, the topic of this study. I examined the habitat selection, nocturnal movement and potential rate of encounter with quail nesting locations by coyotes (Canis latrans), bobcats (Lynx rufus), and raccoons (Procyon lotor) at the Rolling Plains Quail Research Ranch, a private 19 km2 ranch in the Rolling Plains ecoregion of west Texas. My study had 2 objectives: (1) to compare the habitat use of mesopredators in the Rolling Plains to the nesting habitat of bobwhites, and (2) to characterize the nocturnal paths of these mesopredators and measure their overlap with quail nesting locations. I placed GPS collars on 4 bobcats, 7 coyotes and 11 raccoons during the quail nesting seasons of 2009-2011. I used the chi-square test as well as a modified version of the Ivlev’s Electivity Index (1961) to calculate habitat selectivity. I also measured the proximity of the mesopredators and quail nesting locations to roads, water and quail feeders on the ranch. I used fractal analysis to calculate length and tortuosity of nocturnal paths and assessed potential risk to quail nests by determining the intersection rates of mesopredator paths with quail nesting locations. I found that a large difference existed in selectivity of habitat between bobwhite nesting locations and the bobcats and raccoons. Bobwhites selected for the upland grasslands and shrubs and against rocky ridges. Bobcats selected for riparian zones, while raccoons selected for both riparian zones and rocky ridges, neither of which were selected for by nesting quail. Bobcats and male raccoons additionally showed a propensity for road travel, which quail often nested close to. Coyotes selected strongly for grasslands, utilized their home ranges comprehensively and showed a preference for road usage, and thus had the greatest potential encounter rate with quail nest sites. However, coyotes also showed the most linear and direct movement pattern, potentially reducing their efficiency in finding quail nests. This study indicates that coyotes potentially present the largest threat to the nests of quail and female raccoons the least. Management decisions such as the levels of management needed for the 3 species of mesopredators are discussed.

This thesis analyses the lightning protection concept. After a brief introduction to lightning, lightning discharge process and the consequences of a lightning stroke, the worldwide standards for the protection of structures against lightning are analysed and compared in the scope of requirement for the lightning protection. The lightning protection systems since Franklin are traced and the protection methods are re-arranged in the basis of rolling sphere method. after discussing the changing philosophy in lightning protection, cage method is examined and applications of cage method are done according to different protection levels. This thesis seek an answer to the question such that which the safest method for the protection of structures against lightning according to new requirements would be.

In this study an experimental spray-rolling set-up is designed in order to produce rapidly solidified Al-Fe-V-Si flat product. Al-Fe-V-Si alloys produced by rapid solidification powder metallurgy (RSP/M) methods are mostly used in high temperature applications in aerospace and automotive industries. The RSP/M technique used is spray deposition, which is desirable because of the high cooling rates achieved, as a result fine silicide dispersoids and intermetallics are observed in the microstructure which are known to contribute to the mechanical properties i.e. high strength at elevated temperatures, thermal stability, fracture toughness, corrosion resistance. Since spray deposition is a droplet consolidation process a considerable amount of porosity is expected in the final product. In this work, spray rolling process, which consists of spray deposition and subsequent hot twin-rolling stage, is designed and developed by interpreting the results obtained from SEM, XRD, tensile, three point bending and hardness tests of the specimens formed in several design stages. Two original intermetallic phases characterized in this study are V3Si and V2Mg3Al18 .

No description available.

No description available.

The effect of initial microstructures of an 0.05 wt.% C low carbon steel, acicular ferrite (AF), Bainite (B), polygonal ferrite (PF), fine polygonal ferrite (FPF), and a microstructure produced by direct strip casting (DSC) (termed SC), on the deformation and recrystallization behaviour of cold rolled low carbon (LC) steel, was investigated. The initially prepared samples with the initial microstructures were cold rolled to 50, 70 and 90% reductions, then annealed isothermally in the temperature range 580 ??? 680 oC. The microstructures and textures produced by deformation and annealing were studied by optical microscopy, XRD, TEM, SEM and EBSD. The initial microstructures were characterized mainly by optical microscopy and EBSD. Using EBSD, the ferrite grain size of the AF, B and SC samples was considerably larger than that found by optical microscopy with a large fraction of low angle grain boundaries (LAGBs) observed within prior austenite grains. All samples exhibited a very weak texture close to random. After cold rolling, the microstructures of AF and SC contained shear bands with PF and FPF generating deformation bands. For AF and SC, the pearlite phase was more extensively elongated in rolling direction compared with PF and FPF. After 90% cold rolling reduction, PF, FPF and SC consist mainly of the texture component and AF and B . It was found that FPF recrystallized most rapidly followed by B, PF and AF with SC recrystallizing orders of magnitude more slowly due to the solution drag caused by its uniformly distributed higher Mn content. Very strong (???-fibre) texture was generated in cold rolled PF followed by FPF, with AF, SC and B generating very weak textures. The texture evolution during annealing 90% reduction PF was examined in further detail. The behaviour of nucleation and grain growth provides strong evidence of orientated nucleation as the dominant factor for CRA texture development in this material.

Thesis (Ph.D.)--University of Wollongong, 2006. / Typescript. Includes bibliographical references: leaf 252-266.

Thesis (Ph.D.)--Flinders University, Dept. of Chemistry. / Typescript bound. Includes bibliographical references. Also available online.

Thesis (M. S.)--Mechanical Engineering, Georgia Institute of Technology, 2008. / Committee Chair: Rick Neu; Committee Member: Itzhak Green; Committee Member: Jeffrey Streator

Submitted by Aelson Maciera (aelsoncm@terra.com.br) on 2017-09-20T17:37:58Z No. of bitstreams: 1 DissRBS.pdf: 2973698 bytes, checksum: 37eb711fcbda392563dc3155916b5d95 (MD5) / Approved for entry into archive by Ronildo Prado (ronisp@ufscar.br) on 2017-09-20T18:10:55Z (GMT) No. of bitstreams: 1 DissRBS.pdf: 2973698 bytes, checksum: 37eb711fcbda392563dc3155916b5d95 (MD5) / Approved for entry into archive by Ronildo Prado (ronisp@ufscar.br) on 2017-09-20T18:11:02Z (GMT) No. of bitstreams: 1 DissRBS.pdf: 2973698 bytes, checksum: 37eb711fcbda392563dc3155916b5d95 (MD5) / Made available in DSpace on 2017-09-20T18:29:35Z (GMT). No. of bitstreams: 1 DissRBS.pdf: 2973698 bytes, checksum: 37eb711fcbda392563dc3155916b5d95 (MD5) Previous issue date: 2017-03-31 / Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) / Magnesium is considered a promising candidate in applications of storage hydrogen in the solid state, due, among other factors, to its low relative cost and high gravimetric capacity (7,6 wt%.). For magnesium, the use of transition metals as additives may show great improvements in the kinetics of hydrogen absorption/desorption. Different additives can have different functionalities, for example, reducing the energy barrier for H2 adsorption and acting as a heterogeneous nucleating agent in the kinetics of phase transformation. In this research, the main effects of the use of zirconium (Zr) as an additive of the magnesium for the purposes of hydrogen storage in bulks produced by rapid solidification in melt-spinning furnace and cold rolling were studied in detail. Basically, structural characteristics were related to the behavior of absorption / desorption. The alloy produced by cold rolling showed behavior of activation and absorption similar to the pure Mg which was produced by the same route. For the route processed by melt spinning, the use of zirconium as additive has presented a deleterious effect on the activation. However, after activation, the kinetics of absorption exhibit behavior similar to pure Mg. The activation had significantly improved after mechanical or thermal processing, however, the structural characteristics that permeate this effect still have a lack of studies. For both process route, the desorption kinetics presented excellent results, reducing the complete reaction in a few minutes. With the results obtained it is possible to conclude that the use of zirconium as an additive in magnesium alloys has no beneficial effect on absorption. In the other hand, the desorption is extremely attractive. After exposure to air, it was verified that both compositions presented formation of contaminants on the surface and this made the activation a difficult way. However, this effect was more latent in pure magnesium. / O magnésio é considerado um candidato promissor em aplicações de armazenagem de hidrogênio no estado sólido, devido, entre outros fatores, ao seu baixo custo relativo e elevada capacidade gravimétrica, 7,6% em peso. Para o magnésio, o uso de metais de transição como aditivos pode apresentar melhoras significativas na cinética de absorção/dessorção de hidrogênio. Diferentes aditivos podem ter diferentes funcionalidades, por exemplo, reduzir a barreira energética para a adsorção de H2 e atuar como agente inoculante de nucleação heterogênea na cinética de transformação de fase. Neste trabalho, foram estudados em detalhes os principais efeitos provenientes da utilização de zircônio como aditivo ao magnésio para fins de armazenagem de hidrogênio em massas metálicas volumosas (do inglês, bulks) produzidas por solidificação rápida em forno melt-spinning (da sigla em inglês, MS) e laminação a frio (do inglês, CR, cold rolling). Basicamente, relacionaram-se características estruturais ao comportamento de absorção/dessorção. A liga produzida por laminação a frio apresentou comportamento de ativação e absorção semelhante ao Mg puro produzido pela mesma rota. Para o material processado por melt-spinning, o uso do zircônio como aditivo apresentou efeito deletério na ativação. Contudo, após a ativação, a cinética de absorção exibe comportamento semelhante ao Mg puro. Posteriores processamentos mecânico ou térmico melhoraram significativamente a ativação, contudo, as características estruturais que permeiam tal efeito ainda carecem de estudos. Para ambas as rotas de processamento, a cinética de dessorção apresentou ótimos resultados, reduzindo em poucos minutos a reação completa. Com os resultados obtidos se conclui que o uso do zircônio como aditivo em ligas de magnésio não apresenta efeitos benéficos na absorção. Todavia, a dessorção da liga com Zr é extremamente atrativa. Após exposição ao ar, verificou-se que ambas as composições apresentaram formação de contaminantes sobre a superfície e, isso dificultou a ativação, porém, este efeito foi mais evidente no magnésio puro.