No description available.

Seepage direction is crucial for understanding the critical state and development of piping erosion. A stress-controlled apparatus was designed to investigate the piping behavior of cohesionless soil under upward flow condition. The components of the new apparatus included a loading chamber, a vertical and confining loading system, an upstream water supply device, a soil-water separating system, and a water collecting system. The loading chamber provides space for a soil specimen setting and loading. The combination of a vertical and a confining loading system was designed to apply complex stresses to a soil specimen. Under the stresses, the specimen was then eroded by the gradually increasing hydraulic head supplied by the water supply system. The eroded particle and spilling water were collected and detected by the soil-water separating system and the water collecting system. A series of experiments were carried out using the new apparatus. Results demonstrated the repeatability experiments and usefulness of the apparatus. The new apparatus allowed us to investigate the piping behavior under different stress states and hydraulic gradients. With this new apparatus and experiments, we found that lower and high critical hydraulic gradients (CHGs) should be included as the criteria of piping development based on the relationship between the hydraulic gradient and the seepage response. In addition, the stress state on the CHG and the particle erosion rate played important roles in the piping development. The outer pressure on the specimen can retard the development of erosion. In contrast, the hydraulic gradient was found to be positively correlated to the erosion rate. Results also indicated that a specimen would collapse once the amount of eroded small particles exceeds the critical value of 46.5 % of the soil.

Made available in DSpace on 2016-12-08T16:24:23Z (GMT). No. of bitstreams: 1 PGCA15MA184.pdf: 964703 bytes, checksum: 9b63fdeda6cbc9b89c700c8427b99a28 (MD5) Previous issue date: 2015-08-28 / The cryopreservation of somatic cells has been highlighted not only in the preservation of germplasm, but also in the maintenance of genotypes used for the induction of pluripotency, development of strains and cloning by nuclear transfer. The study of the effects of controlled stress in somatic cells or gametes have shown that, in addition to providing increased survival under experimental conditions, it may influence other parameters like the growth pattern in culture. Bovine fibroblasts obtained by standard procedure from a cartilage explant were evenly distributed in four experimental groups as described below: fibroblasts in culture were subjected for 4 minutes to negative pressure 200, 500 and 800 mbar, immediately (PN0h) or 3 hours before (PN3h) freezing, performed in a standard solution (10% DMSO in D-MEM). After trypsinization, the cells were loaded in 0.25 mL straws in a concentration of 1 x 106 cells / mL, and total volume of 200 μL. The straws were sealed and stabilized in a refrigerator (5-7 °C) for 30 minutes, and then exposed to nitrogen vapor (4 cm above the surface) for 5 minutes when were dipped therein. Thawing was performed in a water bath at 36 °C for 20 seconds. Fibroblasts not subjected to pressure were used as frozen (CC) and fresh (FC) controls. There was evaluated the post-thaw viability and subsequently the cell replication index, based on the population doubling time (PDT) performed each 24 h intervals, during 8 days. At each evaluation, the cells of one well of each group were trypsinized and the number of viable cells determined by hemocytometric chamber after staining with Trypan Blue. PDT was determined using the algorithm available online (http://www.doubling-time.com): TD = t x lg2/(lgNt lgN0). Data were submitted to ANOVA and T student test, with 5% significance level. The average cell survival of control group (89.8%) and PN500 0h (88.1%) were higher than all other groups. The PDT average time of all frozen cells was 33.2 h. The PDT time was similar in fresh (27.5 ± 0.35 h), frozen control (30.1 ± 2.3 h) and PN500 0h (32.4 ± 1.6 h) groups. The lowest PDT time was observed in the PN800 0h (21,9h) group. The freezing in plastic straws with 10% DMSO was adequate to cryopreserve bovine fibroblasts allowing high survival rates. It was not observed negative effects of submission to the negative pressure just before freezing, and the level of 200 and 500 mbar resulted in growth rates similar to the obtained with fresh fibroblasts. Although the negative pressure has not increased cryotolerance in bovine fibroblasts, it determined changes in the behavior of these cells during the post-thaw culture. New evaluations should be performed to assess cells subjected to negative pressure in the development of animal clones / A criopreservação de células somáticas vem se destacando não apenas como aliada na preservação de germoplasma, mas também na manutenção de genótipos utilizados para a indução de pluripotencia, formação de linhagens e clonagem por transferência nuclear. O estudo dos efeitos do estresse controlado em gametas ou células somáticas tem demonstrado que, além de proporcionar maior sobrevivência em condições experimentais, outros parâmetros podem ser influenciados, como por exemplo, o padrão de crescimento em cultivo. Para isto, fibroblastos bovinos de primeira passagem, obtidos por procedimento padrão de explantação de cartilagem, foram distribuídos uniformemente em quatro grupos experimentais conforme descrito a seguir: Fibroblastos em cultivo foram submetidos por 4 minutos à pressão negativa de 200, 500 e 800 mbar, imediatamente (PN0h) ou 3horas antes (PN3h) do congelamento, realizado em solução padrão (10% DMSO em D-MEM). Após a tripsinização, as células eram envasadas em uma concentração de 1 x 106 células/mL, em palhetas de 0,25 mL, num volume total de 200 μL. As palhetas eram seladas e estabilizadas em geladeira (5-7 ˚C) por 30 minutos, expostas ao vapor de nitrogênio (4 cm acima da superfície) por 5 minutos, e então mergulhadas no mesmo. O descongelamento era realizado em banho-maria a 36 °C por 20 segundos. Fibroblastos não submetidos à pressão foram utilizados como controles congelado (CC) e fresco (FC). Foram avaliados a viabilidade pós-congelamento, e posteriormente o índice de replicação, baseado no tempo de duplicação da população (PDT) celular, com intervalos de 24h e duração de 8 dias. A cada avaliação, um poço de cada grupo era tripsinizado sendo o número de células viáveis determinado em câmara hemocitométrica, após a coloração com Azul de Trypan. O PDT foi 10 12 determinado utilizando-se o algoritmo disponível online (http://www.doubling-time.com): TD = t x lg2/(lgNt lgN0). Os dados foram submetidos à ANOVA e teste T Student, com 5% de significância. A sobrevivência celular média dos grupos controle (89,8%) e PN500 0h (88,1%) foram superiores aos outros grupos. O tempo médio de PDT de todas as células congeladas foi 33,2h; o tempo de PDT foi semelhante nos grupos fresco (27,5 ± 0,35 h), controle congelado (30,1 ± 2,3 h) e PN500 0h (32,4 ± 1,6 h), o menor tempo foi observado no grupo PN800 0h (21,9 h). As palhetas plásticas se mostraram adequadas para o congelamento de fibroblastos bovinos, não sendo observados efeitos negativos da submissão à pressão negativa imediatamente antes do congelamento, sendo os valores de 200 e 500 mbar os que possibilitaram as melhores taxas de crescimento. Muito embora o emprego de pressão negativa não tenha aumentado a criotolerância de fibroblastos bovinos, determinou mudanças no comportamento destas células durante o cultivo pós-descongelamento. Novas avaliações devem ser realizadas para avaliar a qualidade das células submetidas à pressão negativa, no desenvolvimento de clones animais

The terminations and the joints are the basic accessories of the power cables. Power cables require electrical stress control when terminated. Since there are different types of terminations, the analysis should be done to choose the proper method for electric field control problem at the terminations. Throughout this study two different types of termination methods are investigated by using the finite element analysis program (ANSYS): Stress Controlled Termination Model with Deflector and Stress Control Tube (SCT). The results are compared with those obtained for a cable without stress control model termination. The numerical calculations are also compared with the measurements obtained by an experimental model: the electrolytic tank model.

No description available.

Este trabalho teve como objetivo principal investigar, do ponto de vista volumétrico, qual seria o número de giros necessário, no Compactador Giratório Superpave (CGS), para produzir corpos de prova com características similares aos produzidos com a energia 50 golpes no compactador Marshall, para misturas tipo Stone Matrix Asphalt (SMA) com volume de vazios igual a 4%. Como complemento, realizaram-se dosagens no CGS com 100 giros, visando avaliar o impacto do aumento da energia de compactação no teor de projeto, também para volume de vazios igual a 4%, em comparação aos CPs compactados com o número de giros equivalente à Marshall determinada anteriormente. Foram utilizadas duas faixas granulométricas de misturas SMA: a com Tamanho Máximo Nominal (TMN) 7,93 mm do DER-SP e a com TMN 12,5 mm da AASHTO. Para todas as misturas foram avaliadas as propriedades mecânicas de corpos de prova com 4% de volume de vazios. Dos resultados dos ensaios concluiu-se que o número de giros no CGS para produzir misturas com volume de vazios igual a 4% nos teores de asfalto de trabalho Marshall são similares para as duas faixas granulométricas utilizadas. Por outro lado, a dosagem com 100 giros no CGS reduziu significativamente o teor de asfalto de trabalho para as duas faixas estudadas em comparação com os teores de trabalho obtidos das dosagens Marshall e no CGS com os números de giros equivalentes. Com relação às propriedades mecânicas, as resistências à tração e os módulos de resiliência dos corpos de prova produzidos com 100 giros no CGS são, de uma maneira geral, um pouco menores que os valores obtidos nos corpos de prova compactados no compactador Marshall, independente da faixa granulométrica, porém maiores que os valores obtidos para a compactação giratória nas energias equivalentes. A vida de fadiga para a faixa mais fina é significativamente maior para os corpos de prova compactados com 100 giros em comparação com a compactação Marshall e para a faixa mais grossa manteve-se na mesma ordem de grandeza da obtida para a compactação Marshall. Para as misturas ensaiadas, não foi constatado influência da compactação no dano causado pela umidade induzida / The aim of the work was to investigate, in terms of volumes properties, which would be the number of gyrations required in the Superpave Gyrations Compactor (SGC), to produce samples with characteristics similar to the energy produced with 50 blows in the Marshall Compactor, for Stone Matrix Asphalt (SMA) mixtures with voids content equal to 4%. As a complement, samples designed in the SGC with 100 gyrations, were made to evaluate the impact of increased compaction energy in the binder content, also for voids content equal to 4%, compared to the samples compacted with a number of gyrations equivalent to Marshall, as previously determined. It was used two different aggregates gradations for SMA mixtures: Nominal Maximum Size (NMS) 7,93 mm of the DER and the NMS 12,5 mm of the AASHTO. The mechanical properties of all samples were evaluated with voids content of 4%. The number of gyrations in the SGC to produce mixtures containing voids content equal to 4% for the Marshall`s binder content are similar for both aggregates gradations used. On the other hand, the SMA mixture design with 100 gyrations reduced the binder content for both gradations in comparison with the binder content obtained from Marshall Compaction and SGC with the equivalent number of gyrations. Concerning mechanical properties, the tensile strength and resilient modulus of the samples produced with 100 gyrations in the SGC are, generally, slightly lower than the values obtained with the samples compacted in the Marshall compactor, independent of the aggregate gradations, but higher than the values obtained with the samples compacted with a equivalent energy in the SGC. The fatigue life for the fine gradation (NMS=7,93mm) is significantly higher for the samples compacted in the SGC with 100 gyrations compared with the Marshall compaction, and for the coarse gradation (NMS=12,5 mm) remained in the same order of magnitude that of the Marshall compaction. It was not observed any influence of the compaction method in the induced damage caused by moisture

Este trabalho teve como objetivo principal investigar, do ponto de vista volumétrico, qual seria o número de giros necessário, no Compactador Giratório Superpave (CGS), para produzir corpos de prova com características similares aos produzidos com a energia 50 golpes no compactador Marshall, para misturas tipo Stone Matrix Asphalt (SMA) com volume de vazios igual a 4%. Como complemento, realizaram-se dosagens no CGS com 100 giros, visando avaliar o impacto do aumento da energia de compactação no teor de projeto, também para volume de vazios igual a 4%, em comparação aos CPs compactados com o número de giros equivalente à Marshall determinada anteriormente. Foram utilizadas duas faixas granulométricas de misturas SMA: a com Tamanho Máximo Nominal (TMN) 7,93 mm do DER-SP e a com TMN 12,5 mm da AASHTO. Para todas as misturas foram avaliadas as propriedades mecânicas de corpos de prova com 4% de volume de vazios. Dos resultados dos ensaios concluiu-se que o número de giros no CGS para produzir misturas com volume de vazios igual a 4% nos teores de asfalto de trabalho Marshall são similares para as duas faixas granulométricas utilizadas. Por outro lado, a dosagem com 100 giros no CGS reduziu significativamente o teor de asfalto de trabalho para as duas faixas estudadas em comparação com os teores de trabalho obtidos das dosagens Marshall e no CGS com os números de giros equivalentes. Com relação às propriedades mecânicas, as resistências à tração e os módulos de resiliência dos corpos de prova produzidos com 100 giros no CGS são, de uma maneira geral, um pouco menores que os valores obtidos nos corpos de prova compactados no compactador Marshall, independente da faixa granulométrica, porém maiores que os valores obtidos para a compactação giratória nas energias equivalentes. A vida de fadiga para a faixa mais fina é significativamente maior para os corpos de prova compactados com 100 giros em comparação com a compactação Marshall e para a faixa mais grossa manteve-se na mesma ordem de grandeza da obtida para a compactação Marshall. Para as misturas ensaiadas, não foi constatado influência da compactação no dano causado pela umidade induzida / The aim of the work was to investigate, in terms of volumes properties, which would be the number of gyrations required in the Superpave Gyrations Compactor (SGC), to produce samples with characteristics similar to the energy produced with 50 blows in the Marshall Compactor, for Stone Matrix Asphalt (SMA) mixtures with voids content equal to 4%. As a complement, samples designed in the SGC with 100 gyrations, were made to evaluate the impact of increased compaction energy in the binder content, also for voids content equal to 4%, compared to the samples compacted with a number of gyrations equivalent to Marshall, as previously determined. It was used two different aggregates gradations for SMA mixtures: Nominal Maximum Size (NMS) 7,93 mm of the DER and the NMS 12,5 mm of the AASHTO. The mechanical properties of all samples were evaluated with voids content of 4%. The number of gyrations in the SGC to produce mixtures containing voids content equal to 4% for the Marshall`s binder content are similar for both aggregates gradations used. On the other hand, the SMA mixture design with 100 gyrations reduced the binder content for both gradations in comparison with the binder content obtained from Marshall Compaction and SGC with the equivalent number of gyrations. Concerning mechanical properties, the tensile strength and resilient modulus of the samples produced with 100 gyrations in the SGC are, generally, slightly lower than the values obtained with the samples compacted in the Marshall compactor, independent of the aggregate gradations, but higher than the values obtained with the samples compacted with a equivalent energy in the SGC. The fatigue life for the fine gradation (NMS=7,93mm) is significantly higher for the samples compacted in the SGC with 100 gyrations compared with the Marshall compaction, and for the coarse gradation (NMS=12,5 mm) remained in the same order of magnitude that of the Marshall compaction. It was not observed any influence of the compaction method in the induced damage caused by moisture

Ultrafeinkörnige metallische Werkstoffe haben verstärkt wissenschaftliche Bedeutung erlangt. Um dieser neuartigen Werkstoffklasse über die grundlagenorientierte Forschung hinaus einen Einsatz in technischen Anwendungen zu ermöglichen, ist es notwendig, deren Verhalten unter verschiedenen einsatzrelevanten Belastungsbedingungen vorhersagen zu können. In der vorliegenden Arbeit wird das Schädigungsverhalten einer ultrafeinkörnigen Aluminiumlegierung in den Bereichen der hochzyklischen (HCF) und niedrigzyklischen (LCF) Ermüdung sowie des Rissfortschritts untersucht. Im Mittelpunkt steht dabei die Identifikation der mikrostrukturell wirksamen Mechanismen bei der Entstehung und Ausbreitung von Ermüdungsrissen. Es werden ein homogen ultrafeinkörniger und ein bimodaler Zustand sowie verschiedene duktilitätsoptimierte Zustände betrachtet und systematisch der Einfluss der Korngröße, der Korngrößenverteilung, der Ausscheidungscharakteristik sowie der Festigkeit und Duktilität auf das Ermüdungs- und Rissfortschrittsverhalten ermittelt. Die Untersuchungen zeigen, dass das Schädigungsverhalten der ultrafeinkörnigen Aluminiumlegierung insbesondere durch die Korngröße und Korngrößenverteilung sowie den Kohärenzgrad der festigkeitssteigernden Ausscheidungen beeinflusst wird.

Ultrafeinkörnige metallische Werkstoffe haben verstärkt wissenschaftliche Bedeutung erlangt. Um dieser neuartigen Werkstoffklasse über die grundlagenorientierte Forschung hinaus einen Einsatz in technischen Anwendungen zu ermöglichen, ist es notwendig, deren Verhalten unter verschiedenen einsatzrelevanten Belastungsbedingungen vorhersagen zu können. In der vorliegenden Arbeit wird das Schädigungsverhalten einer ultrafeinkörnigen Aluminiumlegierung in den Bereichen der hochzyklischen (HCF) und niedrigzyklischen (LCF) Ermüdung sowie des Rissfortschritts untersucht. Im Mittelpunkt steht dabei die Identifikation der mikrostrukturell wirksamen Mechanismen bei der Entstehung und Ausbreitung von Ermüdungsrissen. Es werden ein homogen ultrafeinkörniger und ein bimodaler Zustand sowie verschiedene duktilitätsoptimierte Zustände betrachtet und systematisch der Einfluss der Korngröße, der Korngrößenverteilung, der Ausscheidungscharakteristik sowie der Festigkeit und Duktilität auf das Ermüdungs- und Rissfortschrittsverhalten ermittelt. Die Untersuchungen zeigen, dass das Schädigungsverhalten der ultrafeinkörnigen Aluminiumlegierung insbesondere durch die Korngröße und Korngrößenverteilung sowie den Kohärenzgrad der festigkeitssteigernden Ausscheidungen beeinflusst wird.