Made available in DSpace on 2014-06-11T19:35:09Z (GMT). No. of bitstreams: 0 Previous issue date: 2006-06-29Bitstream added on 2014-06-13T19:45:06Z : No. of bitstreams: 1 aragao_bjg_dr_araiq.pdf: 5277233 bytes, checksum: f706ea4557c407c48802037155716b69 (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / O assunto deste trabalho é o envelhecimento acelerado e natural de fibras ópticas de sílica vítrea. Este envelhecimento envolveu uma fibra óptica não cabeada, fabricada em 2000, que foi envelhecida de duas formas. O objetivo dos dois tipos de envelhecimento foi investigar a influência da água molecular e da água dissolvida na sílica na confiabilidade mecânica da fibra óptica. Baseado nos parâmetros mecânicos, químicos e físicos analisados, foi verificado se o envelhecimento acelerado de fibra óptica pode ser comparado com o envelhecimento natural. Concluiu-se que o envelhecimento acelerado de até 50 dias apresenta semelhanças com o envelhecimento natural. Esse trabalho vem assim complementar outros trabalhos realizados envolvendo envelhecimento de fibras ópticas de sílica em meio aquoso, abordando, entretanto, um aspecto pouco investigado: a interação da água molecular com a estrutura da sílica próximo da superfície vítrea em baixas temperaturas. / This work deals with artificial ageing and with field ageing of vitreous silica optical fibers. Artificial ageing was done with a non cabled optical fiber, manufactured in the year 2000, which was exposed to two ageing conditions. The aim of the ageing treatments was to investigate the effect of molecular water and chemically dissolved water on the mechanical reliability of optical fibers. The purpose was to verify if artificial ageing is comparable to field ageing regarding the mechanical, chemical and physical parameters investigated. It was concluded that the artificial ageing treatment up to 50 days showed some similarities with field ageing. This work complements others on ageing of optical fibers in aqueous media, addressing a less investigated subject, namely the interaction of molecular water with silica structure at low temperature close to the fiber surface.

Made available in DSpace on 2015-05-14T16:53:18Z (GMT). No. of bitstreams: 0 Previous issue date: 2015-02-06Bitstream added on 2015-05-14T16:59:03Z : No. of bitstreams: 1 000825155.pdf: 1531867 bytes, checksum: faa2b29cb35354567d34fa54e2bbcf10 (MD5) / Este trabalho refere-se ao processamento de compósitos termoplásticos obtidos a partir de fibras de carbono tratadas por meio de técnicas assistidas por plasma. Os tratamentos empregados foram Descarga Elétrica com Barreira Dielétrica (DBD), que é realizada em pressão atmosférica, envolvendo menores energias e a Implantação Iônica por Imersão em Plasma (3IP), que é realizada em baixa pressão, envolvendo energias mais elevadas. Após o tratamento, foi realizada a caracterização das amostras tratadas e não tratadas para efeito de comparação e também para verificar qual tratamento foi mais eficaz na obtenção de melhores propriedades físico-químicas da fibra para a obtenção dos compósitos termoplásticos, os quais foram produzidos pelo método de moldagem por compressão a quente. Várias técnicas de caracterização foram empregadas, tais como: microscopia eletrônica de varredura, microscopia de força atômica, espectroscopia Raman, espectroscopia de fotoelétrons excitados por raios X, difração de raios-X, e alguns ensaios mecânicos do compósito, tais como: testes de cisalhamento interlaminar e análise dinâmico-mecânica. Após a análise dos resultados, verificou-se que os tratamentos DBD e 3IP são ferramentas eficazes para melhorar a adesão da interface fibra/matriz polimérica, devido ao aumento da rugosidade da fibra e da introdução de grupos polares em sua superfície. Adicionalmente, houve um aumento da resistência ao cisalhamento dos compósitos obtidos a partir de fibras tratadas por ambos os processos a plasma (DBD e 3IP) / In this it has been carried out the processing of thermoplastic composites obtained from carbon fibers (CF) treated by plasma assisted techniques. The employed treatments were Dielectric Barrier Discharge (DBD) that is performed in atmospheric pressure, involving low energy and Plasma Immersion Ion Implantation (PIII), which is held in low pressure regime, consisting of higher energies. After these treatments, both treated and untreated samples, were characterized. A comparison of the results was carried out to determine which treatment is most effective to achieve better physico-chemical properties on the fibers to obtain thermoplastic composites, which were produced by hot compression molding. Several characterization techniques were employed, such as scanning electron microscopy (SEM), atomic force microscopy (AFM), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), X-ray diffraction, and some mechanical tests of the composites, such as interlaminar shear strength (ILSS) and dynamic mechanical analysis (DMA). After analyzing the results, it was verified that the DBD and PIII treatments are effective tools for improving the adhesion of the carbon fiber/polymeric matrix interface, due to the CF roughness increasing and the introduction of polar groups on the carbon fiber surface. Additionally, it was noticed an increase of composites shear strength that were produced with treated carbon fibers (DBD and PIII)

Master of Science / Department of Animal Sciences and Industry / Jim Nelssen / A thorough literature review on feeding vitamin D₃ and 25(OH)D₃ revealed a large amount of research conducted in swine and poultry. In general, increasing vitamin D₃ concentrations or adding 25(OH)D₃ to the maternal diet increases the vitamin D₃ status of the dam and often the progeny as well. Varying results have been reported on the practical and valuable impacts of this elevated status with some topics including improved sow performance, changes in muscle fiber morphometrics, and growth performance to market. The first experiment used a total of 69 sows and the progeny from one group of 22 sows to determine the effects of feeding a combination of vitamin D₃ and 25(OH)D₃ to the sow. Differences in sow productivity and growth performance of progeny due to dietary treatment were not observed (P > 0.05). When pigs were sacrificed at birth, there were no treatment effects for all fiber morphometric measures (P > 0.170), except primary fiber number and the ratio of secondary to primary muscle fibers (P < 0.014). Pigs from the CON and DL fed sows had less primary fibers than pigs from sows fed the DH treatment (P < 0.046), but did not differ from each other (P = 0.732). These results suggest progeny went through a longer prenatal period of primary myogenesis which delayed the onset of secondary myogenesis. Pigs from DL fed sows had a smaller secondary to primary muscle fiber ratio compared to pigs from sows fed the CON treatment (P = 0.016), with pigs from sows fed DL treatment not differing from either (P > 0.057). There were treatment x time interactions for all sow and pig serum metabolites (P < 0.001). Therefore, we chose to compare treatment means within time period. At all time periods, sow serum 25(OH)D₃ concentrations differed for all treatments with the magnitude of difference largest at weaning (P < 0.011). The second and third experiment investigated the impact of adding benzoic acid and an essential oil blend to diets and creep feed. When these additives were included in growing pig diets in a 28-d trial, a main effect of time (P < 0.001) was detected where there was no evidence of difference during the first 3 weeks for ADG and G:F, however both responses decreased during the final week of the experiment (P < 0.001) and average pen BW increased (P < 0.001) for all time points. There was a treatment x time interaction (P = 0.003) for ADFI where during the first 3 weeks, there was no evidence of difference due to dietary treatment, but during the final week of the study, pigs consumed more (P = 0.007) of the control diet (2.38 kg/d control vs. 2.24 kg/d benzoic acid paired and essential oil blend). Fecal samples collected provided no evidence of differences (P > 0.05) in fecal pathogens due to dietary treatment. When these additives were included in the maternal diet and in the creep feed, they did not (P > 0.05) affect sow performance or preweaned piglet performance. Fecal swabbing of pigs the day before weaning showed they did not eat the creep feed and, therefore, no (P > 0.05) improvements in growth performance were observed in the nursery. In conclusion, adding benzoic acid and an essential oil blend to diets and creep feed did not affect growth performance and combining vitamin D₃ and 25(OH)D₃ in the maternal diet improved the vitamin D₃ status of the dam and progeny and increased primary muscle fibers at birth.

Made available in DSpace on 2014-06-11T19:28:21Z (GMT). No. of bitstreams: 0 Previous issue date: 2013-09-09Bitstream added on 2014-06-13T19:57:40Z : No. of bitstreams: 1 campos_mc_me_bauru.pdf: 4273679 bytes, checksum: a48966d45c9fcb339b013e2a3bd42e1a (MD5) / Os laminados de compósitos poliméricos possuem um valor já consagrado dentro das aplicações mecânicas e industriais. Sua versatibilidade aliado a suas propriedades mecânicas, estimula o aumento da aplicação, devido em partes pela facilidade de construção, tornando-os competitivos com relação a outros materiais. O conhecimento sobre a matriz polimérica, que possui inúmeras variações e aplicações e sobre o reforço, que neste estudo utilizou tecidos de fibra de carbono em sarja, formaram o prelúdio do trabalho. A análise de compósitos laminados com tecidos bidirecionais em ângulo de 90º, e a variação de três tipos de matriz polimérica, sendo duas do grupo epóxi e uma do grupo epóxi éster vinil, constituíram os laminados. O processo de corte por jato dágua e por fresagem CNC, influenciaram diretamente a rugosidade da superfície de corte dos laminados. Os ensaios mecânicos de tração e flexão, colaborou para identificar qual das três matrizes possui o melhor desempenho. As técnicas de caracterização por microscopia óptica, possibilitou identificar as camadas dos tecidos, a matriz, modos de falhas e a impregnação entre matriz e reforço. A microscopia confocal 3D além de formar imagens em 3D, demonstrou a diferença de rugosidade entre os processos aplicados, sendo confirmados posteriormente pelo ensaio de rugosidade ficando claro que o processo de corte por fresagem CNC é a melhor opção, pois, o processo de corte por jato dágua demonstrou não ser tão eficiente devido a formação de uma superfície com maior rugosidade em virtude da existência de substâncias abrasivas no fluido de corte, provocando micro trincas nos laminados. Os resultados apontaram que a resina epóxi SQ 2004 é a que possui melhores propriedades mecânicas, seguida da resina SQ 2001 da resina epóxi éster vinil Derakane 470 / The laminated polymer composites have a value already established within the mechanical applications and industries. Its versatility coupled with their mechanical properties, stimulates increased use due in part by the ease of construction, making them competitive with respect to other materials. Knowledge of the polymeric matrix that has numerous variations and applicatons on the reinforcement in this study utilized fabrics of carbon fiber twill formed a prelude to the work. The analysis of laminated composites with woven bi-directional angle of 90º, and the variation of three types of polymer matrix, two of the epoxy groups and the epoxy group, vinyl ester, were the laminates. The process of cutting water jet and CNC milling, directly influenced the roughness of the cut surface of the laminate. The tensile test and bending, collaborated to identify which of the three matrices has the best performance. The techniques of characterization by optical microscopy, enabled us to identify the layers of tissue, the matrix failure modes and impregnation betweeen matrix and reinforcement. Confocal microscopy 3D besides forming 3D images showed the difference in roughness between the cutting processes applied, and later confirmed by testing roughness became clear that the process of cutting CNC milling is the best option because the process cutting water jet proved not to be as effective due to the formation of a surface with increased roughness due to the presence of abrasives in the cutting fluid, causing micro-cracks in the laminate. The results showed that the epoxy resin SQ 2004 is the one that has better mechanical properties, then the resin SQ 2001 and the epoxy vinyl ester Derakane 470

Made available in DSpace on 2014-06-11T19:24:46Z (GMT). No. of bitstreams: 0 Previous issue date: 2008-05-12Bitstream added on 2014-06-13T18:21:13Z : No. of bitstreams: 1 fugii_ap_me_ilha_prot.pdf: 6559082 bytes, checksum: e1ddcb7044b10a47da7e5f917d6bce83 (MD5) / Os tubos de concreto são utilizados em larga escala nas canalizações dos sistemas de abastecimento de água em diâmetros superiores a 400 mm, esgoto sanitário, drenagem pluvial, bueiro e travessia. Suas vantagens e aplicabilidade têm motivado diversas pesquisas sobre esse produto, dentre as quais podemos destacar a utilização de tubos de concreto reforçados com fibras de aço em substituição total da armadura. As fibras de aço quando adicionadas ao concreto melhoram algumas propriedades, tais como: tenacidade, limitação de abertura de fissuras e resistência ao impacto. A pesquisa objetiva analisar o comportamento mecânico de protótipos de tubos de concreto confeccionados com diferentes teores de adições de fibras de aço, tais como: 10 kg/m3, 15 kg/m3, 20 kg/m3, 25 kg/m3 e 30 kg/m3, em substituição total da armadura. Também foram fabricados tubos de concreto simples e armados para uma análise comparativa do comportamento mecânico entre aqueles e os tubos com fibras. Os tubos de concreto possuem 600 mm de diâmetro nominal e 1,5 m de comprimento, destinados aos sistemas de drenagem de águas pluviais. As fibras de aço utilizadas possuem fator de forma igual a 75 e apresentam as seguintes características: 60 mm de comprimento médio e 0,80 mm de diâmetro médio. Os corpos-de-prova cilíndricos foram submetidos aos ensaios: resistência à compressão axial, resistência à tração na compressão diametral, e os corpos-de- prova prismáticos foram submetidos aos ensaios de tenacidade enquanto os tubos de concreto foram submetidos aos ensaios: resistência à compressão diametral e absorção de água (amostras retiradas dos tubos após ensaio de compressão diametral). Dos ensaios realizados se destaca o ensaio de compressão diametral pelo fato... / The concrete pipe is widely used in plumbing systems in water supplying in higher diameters 400 mm, sewage, water rain drainage, storm drain and crossing. Its advantages and functions have motivated a lot of researches about this product, among them can point out used concrete pipes reinforced with steel fibers replacing the conventional framework. The steel fibers when added concrete improvement some properties, such as: flexural toughness, limitation crack width and high strain rates strength. The current text refers to a study developed to evaluate the mechanical behavior of manufactured prototypes with steel fibers added in different contents, such as: 10 kg/m3, 15 kg/m3, 20 kg/m3, 25 kg/m3 e 30 kg/m3, replacing the conventional framework. Also were manufactured simple concrete pipes and concrete pipes with framework for analysis to compare the mechanical behavior between that one and steel fibers. The pipes used have 600 mm nominal diameter and 1,5 m length, used in systems in water rain drainage. The steel fibers used have aspect ratio 75 and present characteristics: 60 mm medium length and 0,80 mm medium diameter. The circular specimens were submitted the testing for: compressive strength, tensile strength by diametrical compressive, and the rectangular specimens were submittes the testing for flexural toughness while the concrete pipes were submitted the testing for: diametrical compressive strength and absorption of water (sample retreat of pipes after the testing for diametrical compressive strength). The testing for realized to point for diametrical compressive strength because the testing for the same concrete pipe and all particular characteristics for observed. The Brazilian specification NBR 8890 (ABNT, 2007) specify the testing for diametrical compressive... (Complete abstract click electronic access below)

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Submitted by Ana Guimarães Pereira (agpereir@ucs.br) on 2017-12-20T10:57:46Z No. of bitstreams: 1 Tese Daniel Teixeira.pdf: 146154 bytes, checksum: 7c1e5b79cce0b660c6eff1df7e5cb84d (MD5) / Made available in DSpace on 2017-12-20T10:57:46Z (GMT). No. of bitstreams: 1 Tese Daniel Teixeira.pdf: 146154 bytes, checksum: 7c1e5b79cce0b660c6eff1df7e5cb84d (MD5) Previous issue date: 2017-12-20 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior, CAPES