Thesis (M.S.)--University of Missouri-Columbia, 2007. / The entire dissertation/thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file (which also appears in the research.pdf); a non-technical general description, or public abstract, appears in the public.pdf file. Title from title screen of research.pdf file (viewed on April 1, 2008) Includes bibliographical references.

Thesis (M.S.)--University of Missouri-Columbia, 2006. / The entire dissertation/thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file (which also appears in the research.pdf); a non-technical general description, or public abstract, appears in the public.pdf file. Title from title screen of research.pdf file (viewed on April 17, 2009) Includes bibliographical references.

Thesis (M.S.)--University of Alabama at Birmingham, 2004. / Printout. Includes bibliographical references (leaves 264-266). Also available online.

Thesis (Ph. D.)--Rutgers University, 2007. / "Graduate Program in Mechanical and Aerospace Engineering." Includes bibliographical references (p. 141-147).

Thesis (Ph.D.) - University of Queensland, 2005. / Includes bibliography.

Thesis (M.S.)--University of Missouri-Columbia, 2005. / The entire dissertation/thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file (which also appears in the research.pdf); a non-technical general description, or public abstract, appears in the public.pdf file. Title from title screen of research.pdf file viewed on (January 23, 2007) Includes bibliographical references.

Polymer matrix composites (PMCs) offer several advantages compared to traditional metallic counterparts when employed in high-performance products that need to be lightweight, yet strong enough to sustain harsh loading conditions - such as aerospace components and protective structures in military applications- armours, helmets, and fabrications retrofitted to transport vehicles and bunkers. These are often subjected to highly dynamic loading conditions under blast and ballistic impacts. Severe impact energy involved in these dynamic loading events can initiate discrete damage modes in PMCs such as matrix cracking, matrix splitting, delamination, fibre-matrix debonding, fibre micro-buckling and fibre pull-out. Interaction of these damage modes can severely reduce the load carrying capacity of such structures. This needs to be understood to design structures with improved resistance to such loading.

A hipersensibilidade dentinária (HD) é descrita na literatura como uma dor aguda, de curta duração, provocada por estímulos térmico, tátil, osmótico, químico ou evaporativo em região de exposição dentinária, não sendo atribuída à dor causada pela presença de defeito ou doença de origem dentária. Esse tipo de acometimento tem sido cada vez mais reportado pelos pacientes, em vista disso, o objetivo desse estudo foi avaliar a extensão e gravidade de HD, bem como sua associação com indicadores periodontais [índice de placa (IP), índice gengival (IG) e recessão gengival (RG)] em uma amostra composta por 132 indivíduos com HD diagnosticada por meio de estímulo térmico/evaporativo (jato de ar) associada à escala Schiff. Análises descritivas foram feitas e as porcentagens médias de IP e IG foram estimadas considerando 6 sítios por dente e também 3 sítios das faces vestibulares. Além disso, os dados foram analisados através de modelos uni e multivariados utilizando análises de regressão linear. A média de idade foi de 30.66±10.33, sendo o sexo feminino mais afetado pela HD (83.3%). Foi possível observar que a HD esteve associada à recessão gengival. A prevalência de dentes com recessão gengival foi de 17.17%, enquanto que a prevalência de recessão em dentes com HD foi de 77.1% e a média de recessão vestibular foi de 1.58±0.87. Quando considerada a média de dentes com 1 ou mais milímetros de recessão, observou-se que, em média, 4.48 dos dentes apresentaram esta condição. Um maior número médio de dentes com recessão e menores escores médios de IP nos sítios vestibulares apresentaram-se signicativamente associados ao número médio de dentes com HD. A gravidade da HD nos pacientes foi significativamente influenciada por maior média de recessão gengival e foi maior nos pacientes do sexo feminino. Dentes que possuíam maiores médias de recessão e maiores escores médios de IP e menores de IG nos sítios vestibulares apresentaram maiores valores na escala Schiff (p<0.05). Frente aos achados, é possível observar que portadores de HD têm um grande número de dentes afetados por esta condição e que estes apresentam recessão. Além disto, nos dentes que apresentam HD, a gravidade desta está associada a presença de mais placa e melhor condição gengival, além da extensão da recessão. / Dentin hypersensitivity (DH) is described in the literature as an acute short-term pain caused by thermal, tactile, osmotic, chemical or evaporative stimuli in the region of dentin exposure and not attributed to pain caused by the presence of defect or disease of dental origin. Therefore, the aim of this study was to evaluate the extent and severity of DH, as well as its correlation with periodontal indicators [plaque index (PI), gingival index (GI) and gingival recession (GR)] in 132 individuals with DH diagnosed by thermal/evaporative (air blast) stimulation associated with the Schiff scale. Descriptive analyzes were made and the mean percentages of PI and GI were estimated considering 6 sites per tooth and also 3 buccal sites. In addition, the data were analyzed using univariate and multivariate models using linear regression analysis. The mean age was 30.66 ± 10.33, female sex being more affected by DH (83.3%). It was possible to observe that DH was associated to gingival recession. The prevalence of teeth with gingival recession was 17.17%, while the prevalence of recession in teeth with DH was 77.1%. The mean of vestibular recession was 1.58 ± 0.87, and when considered the mean teeth with 1 or more millimeters recession, it was observed that, a mean of 4.48 teeth presented this condition. A higher mean number of teeth with recession and lower mean PI scores in the vestibular sites were associated (p<0.001) with the mean number of teeth with DH. The severity of DH in number of patients was significantly influenced by the higher mean of gingival recession and was higher in the female patients. Teeth that had higher recession mean and higher mean PI scores at the buccal sites, but lower GI scores at this sites, presented significantly higher values on the Schiff scale (p <0.05). In view of the findings, it is possible to observe that DH patients have a large number of teeth affected by this condition and that these present gingival recession. In addition, in the teeth that present DH, the severity is associated with the presence of more plaque and better gingival condition, in addition to the extent of the recession.

The present thesis investigates the interaction of a shock wave with a cellular flame and the ensuing mechanisms on the dynamics of the subsequent flame deformation. The inter- action is known to disrupt the flame surface through the Richtmyer-Meshkov instability, hence potentially enhancing the local combustion rates. This study aims to clarify the evolution of a flame when perturbed head-on by a shock wave. Two novel series of experiments were conducted in a vertically-oriented Hele-Shaw cell, which could successfully isolate a quasi-bidimensional cellular flame structure at ambient conditions. In the first configuration, the passage of the shock wave arising in the burned products of a deflagration wave was investigated, while both waves propagated in the same outward direction. In the other configuration, the shock wave centrally emerged in the unburned gases and collided with a cellular flame front traveling in the opposite direction. The event was captured using a Z-type Schlieren imaging system to visualize the growth of the flame cells. Shock characterization was determined in the Hele-Shaw apparatus to estimate the strength of the blast wave generated by energy deposition using a high-voltage igniter or by decoupled detonation from a detonation tube. A combustion study was also performed to determine the laminar flame speed in a mixture of hydrogen-air according to different equivalence ratios in the apparatus. The experiments revealed that inherent cellular flame instabilities are well developed in the observation scale of the Hele-Shaw geometry. The shock-flame complex was therefore analyzed experimentally for selected mixtures. As the shock wave traversed the interface separating the burned and unburned gases, the flame became more corrugated. Following the interaction, the flame cusps were stretched and/or flattened. At later times, the wrinkled interface was reversed and developed finer scales. A time scale analysis was performed to identify the contribution of the competing effects of Richtmyer-Meshkov and Rayleigh-Taylor instabilities on the flame interface deformation. For the case of a shock wave traversing the flame interface from the unburned to the burned side, the early perturbations were mainly governed by the Richtmyer-Meshkov instability. Finally, Rayleigh-Taylor instability resulted from the decaying pressure profile of the blast wave and tended to stabilize the perturbed interface to eventually reverse the cellular structure. Experimental and inert numerical results on the flame cell’s amplitude growth were found to be in good agreement.

Made available in DSpace on 2014-10-09T12:38:19Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T14:04:38Z (GMT). No. of bitstreams: 1 05681.pdf: 6544120 bytes, checksum: 39fb67d11e03881826cd6fa65d2fdde5 (MD5) / Dissertacao (Mestrado) / IPEN/D / Instituto de Pesquisas Energeticas e Nucleares - IPEN/CNEN-SP