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Modeling of Ultrasonic and Terahertz Radiations in Defective Tiles for Condition Monitoring of Thermal Protection SystemsKabiri Rahani, Ehsan January 2011 (has links)
Condition based monitoring of Thermal Protection Systems (TPS) is necessary for safe operations of space shuttles. In the current research Terahertz radiation (T-ray) has been used to detect mechanical and heat induced damages in TPS tiles. Voids and cracks inside the foam tile are denoted as mechanical damage while property changes due to long and short term exposures of tiles to high heat are denoted as heat induced damage.Ultrasonic waves cannot detect cracks and voids inside the tile because the tile material (silica foam) has high attenuation for ultrasonic energy. Instead, electromagnetic terahertz radiation can easily penetrate into the foam material and detect the internal voids although this electromagnetic radiation finds it difficult to detect delaminations between the foam tile and the substrate plate. Thus these two technologies are complementary to each other for TPS inspection.Ultrasonic and T-ray field modeling in free and mounted tiles with different types of mechanical and thermal damages has been the focus of this research. Shortcomings and limitations of FEM method in modeling 3D problems especially at high-frequencies has been discussed and a newly developed semi-analytical technique called Distributed Point Source Method (DPSM) has been used for this purpose.A FORTRAN code called DPSM3D has been developed to model both ultrasonic and electromagnetic problems using the conventional DPSM method. DPSM has been extended from ultrasonic applications to electromagnetic to model THz Gaussian beams, multilayered dielectrics and Gaussian beam-scatterer interaction problems. Since the conventional DPSM has some drawbacks, to overcome it two modification methods called G-DPSM and ESM have been proposed.The conventional DPSM in the past was only capable of solving time harmonic (frequency domain) problems. In this research DPSM has been extended to model DPSM transient problems. This modified technique has been denoted as t-DPSM.Using DPSM, scattering of focused ultrasonic fields by single and multiple cavities in fluid&solid media is studied. A comparison between the radiation forces generated by the ultrasonic energies reflected from two small cavities versus a single big cavity is also carried out.
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Final cutting of shelterwood : harvesting techniques and effects on the Picea abies regeneration /Glöde, Dan, January 1900 (has links) (PDF)
Diss. (sammanfattning) Umeå : Sveriges lantbruksuniv., 2001. / Härtill 4 uppsatser.
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Compréhension des mécanismes d'endommagement de l'interface textile-caoutchouc / Understanding of damage mechanisms of a textile rubber interfaceValantin, Chloé 18 December 2014 (has links)
Les courroies étudiées subissent des sollicitations mécaniques complexes et des variations thermiques jusqu’à 160°C. Pour améliorer leurs durées de vie, les propriétés de l’interface entre le câblé PA 4,6 adhérisé RFL et la matrice EPDM doivent être optimisées. Dans ces travaux, les courroies ont subi un endommagement par fatigue et les essais ont été arrêtés après différents nombres de cycles afin de caractériser l’interface câblé/caoutchouc. Les analyses en microscopie électronique ont révélé trois mécanismes d’endommagement: La dégradation de la structure interne du câblé La propagation de décohésions fibrillaires à l’interface RFL/caoutchouc L’apparition d’arrachements fibre polyamide/RFL Ces endommagements ont été corrélés à des rigidifications interfaciales (nanoindentation), une évolution des propriétés viscoélastiques de la structure (DMA) et une diminution des valeurs d’adhérence (pelage ou arrachement). Des analyses physicochimiques, principalement Tof-SIMS, ont permis de déterminer la composition interfaciale initiale et de corréler son évolution aux endommagements constatés. / Studied belts undergo complex mechanical stress and thermal variations up to 160°C. To enhance their service life, the interfacial properties between the PA 4, 6 cord, coated with RFL, and the EPDM matrix must be improved. In this study, fatigue tests on belts were stopped after various numbers of cycles in order to characterize the interface between cord and rubber. Electron Microscopy revealed three different mechanisms for mechanical damage: Degradation of the inner cord structure Propagation of fibrillar microcracks at the RFL/rubber interface Appearance of RFL/polyamide microfiber debondings This damage was associated with interfacial hardenings (nanoindentation), viscoelastic properties variations of the structure (DMA) and a decrease in adhesive values (peeling or pulling out). Physicochemical analyses, mainly by Tof-SIMS, enabled to determine interfacial composition and to link its evolution with observed mechanical damage.
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Qualidade fisiológica e desempenho agronômico de soja em função do tamanho das sementesFonseca, Nara Rosseti [UNESP] 20 November 2007 (has links) (PDF)
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fonseca_nr_dr_botfca.pdf: 724750 bytes, checksum: de71adb7ebdb6beff40404eafeea026c (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / A separação de sementes por classes de tamanho em soja é uma prática recentemente adotada no Brasil. Essa classificação favorece a precisão da semeadura, a obtenção de população adequada, a eqüidistância de plantas e, ainda, redução da demanda de sementes por área. O objetivo do estudo foi avaliar a influência do tamanho das sementes na qualidade fisiológica, durante o armazenamento, e no desempenho agronômico de duas cultivares de soja, produzidas em três localidades distintas do Estado do Paraná, de acordo com a classificação do tamanho proposto pela Comissão Estadual de Sementes e Mudas – CESM/PR. O trabalho foi conduzido em duas etapas, nos anos de 2005 e 2006. A primeira etapa foi realizada no Laboratório de Análise de Sementes do Departamento de Produção Vegetal - Setor Agricultura (DPV-A), e a segunda na área experimental da Fazenda Lageado, ambas as dependências pertencentes à Faculdade de Ciências Agronômicas (FCA), da Universidade Estadual Paulista (UNESP), em Botucatu-SP. Foi utilizado dois cultivares de ciclo semiprecoce, produzidas e classificadas em dois tamanhos (5,5 e 6,5 mm) em Faxinal, Mauá-da-Serra e Ponta Grossa, todas localizadas no Estado do Paraná. Após classificação mediante emprego de peneiras de crivos circulares, as sementes foram transportadas para o DPV-A da FCA onde foram armazenadas sob condições de ambiente natural (sem controle de temperatura e umidade relativa do ar) por um período de seis meses. Nas avaliações de laboratório ao início do armazenamento foram utilizados os seguintes testes: massa de 100 sementes, retenção de peneiras, dano mecânico (hipoclorito de sódio), porcentagem de sementes verdes, e a cada dois meses do período de armazenamento: teor de água das sementes, teste de germinação, primeira contagem de germinação, comprimento... . / Separation of soybean seeds considering its size class is a recently technique adopted in Brazil. This kind of classification favors sowing precision, obtaining of adequate population and equidistance among plants and, yet, reduction in seed requirement per area. The objective of this research was to evaluate physiological quality of seeds during storage and agronomic performance of two soybean varieties, produced in three different localities from the State of Paraná, according to the size classification suggested by Comissão Estadual de Sementes e Mudas – CESM/PR. The research was carried out in two stages, in the years of 2005 and 2006. The first was carried out in the Laboratório de Análise de Sementes, Departamento de Produção Vegetal - Setor Agricultura (DPV-A), and the second at an experimental area in the Fazenda Lageado, both belonging to the Faculdade de Ciências Agronômicas (FCA), Universidade Estadual Paulista (UNESP), in Botucatu-SP. Two varieties were used, classified as semi-early growth cycle, produced the classification in two sieves (5,5 and 6,5 mm) in Faxinal, Mauá-da-Serra and Ponta Grossa, all located in the State of Paraná. After the classification through the use of screens with round sieves, the seeds were transported to the DPV-A – FCA, where they were stored in environmental conditions (without control of the temperature and relative humidity) for six months. For the laboratorial evaluations before the storage, the following tests were used: weight of 100 seeds, screen retention, mechanical damage (sodium hypochlorite) and percentage of green seeds. During the storage, the seed moisture content, germination, first count of the germination, seed length, seedling dry matter, accelerated aging, electrical conductivity, tetrazolium test, seedling emergence in field and speed of emergence-index were... (Complete abstract, click electronic address below).
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Utilisation des méthodes de Krigeage pour le dimensionnement en fatigue des structures éoliennes posées en mer. / Kriging based methods for the structural damage assessment of offshore wind turbinesHuchet, Quentin 13 December 2018 (has links)
Dans le contexte actuel de transition énergétique, les acteurs de la production électrique (dont EDF) s'orientent de plus en plus vers les technologies "bas carbone", permettant de développer leur mix énergétique et d'assurer une production toujours plus respectueuse de l'environnement. Parmi l'ensemble des alternatives progressivement industrialisées au cours de ces dernières décennies, l'énergie éolienne voit son développement s'accélérer. De nouveaux projets voient le jour, notamment avec le développement de parcs éoliens posés en mer le long des côtes françaises.Afin de garantir une sécurité maximale des installations vis-à-vis des défaillances mécaniques, les ingénieurs doivent mettre en place un ensemble de vérifications ayant pour but d'assurer l'intégrité structurelle pendant une durée de vie donnée. Cette étape, nécessaire à la certification et donc à l'industrialisation du projet, exige un investissement numérique important. Dans le cas particulier de l'estimation de l'endommagement à durée de vie, un ensemble complet d'analyses doit être effectué afin de simuler les réactions structurelles en différents points de la conception et ce, pour l'ensemble des conditions environnementales de chargement possibles (cas de charge). Au total, quelques milliers de simulations correspondant à l'ensemble des situations probables sont à prévoir pour la seule estimation de l'endommagement à durée de vie. De plus, la prise en compte des différents phénomènes physiques du problème (aérodynamique, hydrodynamique, mécanique élastique), ainsi que la considération des non-linéarités des réponses liées à l'asservissement de la turbine, impliquent l'utilisation de codes de résolution temporels et multi-physiques coûteux pour chacune des situations de chargement à simuler.Afin de réduire l'investissement lié à l'estimation de cet endommagement, l'utilisation de méthodes numériques de substitution (également appelées métamodèles) est une alternative prometteuse. Ces méthodologies ont montré leur efficacité dans divers domaines de l'ingénierie permettant d'approcher, par diverses hypothèses statistiques, la réponse de modèles numériques en ne considérant qu'un nombre réduit de simulations.Ce travail de thèse s'est focalisé sur le développement d'outils numériques pour le dimensionnement efficace des structures éoliennes en mer et plus particulièrement sur l'utilisation des métamodèles de Krigeage (ou méthode de régression par processus gaussien) pour l'estimation de l'endommagement mécanique. Sous certaines hypothèses, cette méthode de substitution se prête particulièrement bien à l'approximation des réponses de modèles physiques, notamment grâce à la mise en place facilitée d'architectures itératives d'enrichissement ("active learning strategy"). Deux domaines ont principalement été étudiés : l'estimation rapide des quantités d'endommagement structurel par le développement de la méthode "Adaptive Kriging for Damage Assessment" (AK-DA) et les possibilités d'utilisation de cette dernière dans le cadre d'études de la fiabilité conceptuelle au regard de la tenue à l'endommagement. L'applicabilité de ces méthodes a été illustrée via l'utilisation d'exemples numériques inspirés du contexte industriel et de ses contraintes. / The mechanical certification of wind turbine structures is required for the funding of newoffshore projects on the French coasts. In order to ensure a maximal safety level of installations,a series of structural analyzes are required by the certification bodies. Amongst all, thedamage based computations represent an important numerical effort for EDF. The presentedworks focus on the applicability and the performances of Kriging metamodels for the estimationof the lifetime cumulated damage of offshore wind turbine structures (AK-DA approach)and the damage based reliability assessment of new designs (AK-MCS/AK-DA coupling).
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Avaliação de camadas de proteção para geomembranas de PVC e PEAD / Assessment of the performance of protective layers for PVC and HDPE geomembranesRebelo, Karla Maria Wingler 03 February 2009 (has links)
O presente trabalho investiga o desempenho de geotêxteis e de solos como elementos de proteção para geomembranas de polivinil clorado (PVC) e de polietileno de alta densidade (PEAD). Foram utilizadas geomembranas de PVC com espessuras de 1,0 e 2,0 mm e de PEAD com espessuras de 1,5 e 2,0 mm. Como camadas de proteção utilizaram-se geotêxteis não tecidos de poliéster (PET), com gramaturas de 130, 300, 400 e 600 g/\'M POT.2\', e de polipropileno (PP), com gramatura de 400 e 600 g/\'M POT.2\', além de uma areia de granulometria fina a média e uma areia argilosa típica da região Centro-Oeste do Estado de São Paulo. O estudo foi conduzido através da construção de um aterro experimental para simulação dos danos de instalação em campo e da realização de ensaios índice e de desempenho em laboratório. A eficiência dos materiais de proteção foi avaliada através da análise qualitativa e quantitativa das amostras de geomembranas danificadas. Os resultados dos ensaios de laboratório índice mostraram que a introdução do geotêxtil aumenta a resistência à punção da geomembrana, e que o acréscimo de resistência é função das características de resistência à tração do geotêxtil e da geomembrana. O maior incremento de resistência à punção foi observado na geomembrana com menor resistência à tração. Os resultados dos ensaios de campo mostraram que a introdução do elemento de proteção reduz os danos mecânicos apesar da alteração de algumas das propriedades físicas e de desempenho nas geomembranas. Da análise dos resultados, verificou-se que a eficiência dos geotêxteis no campo não é função de suas características de tração, conforme constatado nos ensaios índices. A análise também sugere que os danos mecânicos no campo foram mais intensos do que nos ensaios de desempenho em laboratório. / The performance of non-woven geotextiles and soils as protection elements of polyvinyl chloride (PVC) and high density polyethylene (HDPE) geomembranes is studied. The materials used comprised PVC geomembranes of 1,0 and 2,0 mm thickness and HDPE geomembranes of 1,5 and 2,0 mm thickness while the protective layers were of non-woven polyester (PET) geotextiles with mass per unit area of 130, 300, 400 e 600 g/\'M POT.2\' and polypropylene (PP) with mass per unit area of 400 e 600 g/\'M POT.2\'. It was also used protective layers made of a fine to medium sand and a typical clayey sand of central area of the State of São Paulo. The study was based on an experimental landfill built to simulate the damage associated to construction procedures and on index and performance laboratory tests. Through qualitative and quantitative analysis of damaged geomembranes, the behavior of each protective element was evaluated. Index laboratory test results have shown that the geotextile is able to increase the geomembrane puncture strength and that the strength increase is related to the tensile strength of geotextile and geomembrane. For similar geotextiles, the larger increase in puncture strength was observed for the geomembrane that presented the lower tensile strength. Visual observation of field tests has shown that the introduction of protective layers reduces the mechanical damage; however some physical and performance properties of geomembrane have changed. It was also observed that the performance of geotextiles in the experimental landfill does not depend on the tensile strength, as observed in laboratory index tests. Test results also suggest that field damage associated to the landfill construction are more intense than that observed in laboratory tests such as the dynamic puncture test.
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Parâmetros de colheita mecanizada na qualidade de sementes e grãos armazenados de feijão comum / Parameters of mechanical harvesting on the quality of stored grains and seeds of common beansSoncela, Rodrigo Ferreira 05 July 2011 (has links)
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Previous issue date: 2011-07-05 / With the expansion of the bean, the mechanized harvesting is becoming increasingly necessary, both due to shortage of manpower, on the increase of crop yield. Therefore, it becomes essential to have knowledge of the variables involved in this operation. So, in this context, the aim of this study is to assess changes in quality of seeds and grains of beans, stored in accordance with parameters of mechanical harvesting. The experiment was conducted in a commercial area in Santa Tereza do Oeste Paraná, using, for the harvest IAPAR 81, combine harvester, with "bean kit" and cylinder axial (adapted). The culture was initiated in the 2009/2010 agricultural year, using line spacing of 0.45 m m-1 14 plants and cultural practices were applied in order to control insects, diseases and weeds. To harvest, harvest times were tested (8, 12 and 16 h), cylinder rotation (300, 340 and 385 rpm) and the harvester forward speed (4, 5 and 6 km h-1). We evaluated the water content, purity, loss and damage to seeds and germination percentage. The grains and seeds harvested were stored and the evaluations done at 0 (control), 45, 90 and 180 days. For the assessment of technological quality, tests were conducted of the cooking time, water absorption before cooking, and the evaluation of the germination, moisture content, weight of 100 seeds. The experiment was conducted in a randomized design and layout of sub-sub divided plot (3 x 3 x 3 - harvesting times, speed and cylinder rotation) with four replicates and storage was the same scheme of analysis in harvest, but evaluated at each storage time. The results were submitted to ANOVA, and comparisons of means were carried out by Tukey test at 5% significance), using the program SISVAR. The parameters evaluated influenced on the quality of grains and seeds. Crop losses were lower at 12 and 4 p.m., at lower rotation speeds and cylinder displacement of the harvester. The purity of seeds was lower at 4 p.m. with a lower rotation speed intermeeting. Mechanical damage was not significant at harvest, with the variation of the parameters for collection, but may have influenced the quality parameters of grain and seeds. There was a gradual increase in the percentage of germination of bean seeds during storage, and there may be an inverse relationship with water content. Damage occurred during harvesting may have influenced the increase of cooking time and reduced water absorption, since there were differences of these parameters within each storage time. No relationship was observed between percentage of water absorption in the grain and cooking time, given that little variation in the first parameter was observed during storage, unlike the cooking time, in which the changes were remarkable / Com a expansão da cultura do feijão, a colheita mecanizada vem se tornando cada vez mais necessária, devido tanto à escassez de mão de obra, quanto ao aumento do rendimento da colheita. Por isso, torna-se indispensável o conhecimento das variáveis envolvidas nessa operação. Assim, dentro deste contexto, o objetivo do presente trabalho é avaliar alterações na qualidade de sementes e grãos de feijão comum, armazenados em função de parâmetros de colheita mecanizada. O experimento foi desenvolvido em área comercial no município de Santa Tereza do Oeste Paraná, utilizando-se, para colheita o feijão IAPAR 81, colhedora automotriz, com kit feijão e cilindro axial (adaptado). A cultura foi implantada no ano agrícola 2009/2010, utilizando espaçamento entre linhas de 0,45 m e 14 plantas m-1 e as práticas culturais foram aplicadas visando ao controle de insetos, doenças e plantas invasoras. Para a colheita, foram testados horários de colheita (8, 12 e 16 h), rotações de cilindro (300, 340 e 385 rpm) e velocidades de deslocamento da colhedora (4, 5 e 6 km h-1). Foram avaliados teor de água, pureza, perdas e danos nas sementes, além da porcentagem de germinação. Os grãos ou sementes, colhidas foram armazenados e as avaliações realizadas aos 0 (controle), 45, 90 e 180 dias. Para a avaliação da qualidade tecnológica foram realizados os testes do tempo de cozimento, absorção de água antes do cozimento, além da avaliação da germinação, teor de água, massa de 100 sementes. O experimento foi conduzido em delineamento inteiramente casualizado e em esquema de parcela sub-sub dividida (3 x 3 x 3- horários de colheita, velocidades de deslocamento e rotação do cilindro) com quatro repetições e para o armazenamento foi o mesmo esquema da análise na colheita, porém avaliado em cada tempo de armazenamento. Os resultados foram submetidos à ANOVA, e comparação de médias pelo Teste de Tukey a 5% de significância), utilizando-se o programa SISVAR. Os parâmetros de colheita avaliados influenciam na qualidade dos grãos e das sementes. As perdas na colheita foram menores nos horários das 12 e 16 h, nas menores rotações de cilindro e velocidades de deslocamento da colhedora. A pureza das sementes foi menor às 16 h com menor rotação na velocidade intermediária. Os danos mecânicos não foram significativos no momento da colheita, com a variação dos parâmetros de colheita, mas podem ter influenciado nos parâmetros de qualidade de grãos e sementes. Ocorreu aumento gradativo da porcentagem de germinação das sementes de feijão com o armazenamento, podendo haver relação inversa com o teor de água. Danos ocorridos durante a colheita podem ter influenciado no aumento de tempo de cozimento e na redução da absorção de água, uma vez que houveram diferenças desses parâmetros dentro de cada tempo de armazenamento. Não se observou relação entre porcentagens de absorção de água nos grãos e o tempo de cozimento dos mesmos, uma vez que pouca variação do primeiro parâmetro foi observada com o armazenamento, diferente do tempo de cozimento, no qual as variações foram marcantes
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Parâmetros de colheita mecanizada na qualidade de sementes e grãos armazenados de feijão comum / Parameters of mechanical harvesting on the quality of stored grains and seeds of common beansSoncela, Rodrigo Ferreira 05 July 2011 (has links)
Made available in DSpace on 2017-05-12T14:48:36Z (GMT). No. of bitstreams: 1
Rodrigo.pdf: 1740507 bytes, checksum: 41a70fb8d7ce76417e5224a860af0d8b (MD5)
Previous issue date: 2011-07-05 / With the expansion of the bean, the mechanized harvesting is becoming increasingly necessary, both due to shortage of manpower, on the increase of crop yield. Therefore, it becomes essential to have knowledge of the variables involved in this operation. So, in this context, the aim of this study is to assess changes in quality of seeds and grains of beans, stored in accordance with parameters of mechanical harvesting. The experiment was conducted in a commercial area in Santa Tereza do Oeste Paraná, using, for the harvest IAPAR 81, combine harvester, with "bean kit" and cylinder axial (adapted). The culture was initiated in the 2009/2010 agricultural year, using line spacing of 0.45 m m-1 14 plants and cultural practices were applied in order to control insects, diseases and weeds. To harvest, harvest times were tested (8, 12 and 16 h), cylinder rotation (300, 340 and 385 rpm) and the harvester forward speed (4, 5 and 6 km h-1). We evaluated the water content, purity, loss and damage to seeds and germination percentage. The grains and seeds harvested were stored and the evaluations done at 0 (control), 45, 90 and 180 days. For the assessment of technological quality, tests were conducted of the cooking time, water absorption before cooking, and the evaluation of the germination, moisture content, weight of 100 seeds. The experiment was conducted in a randomized design and layout of sub-sub divided plot (3 x 3 x 3 - harvesting times, speed and cylinder rotation) with four replicates and storage was the same scheme of analysis in harvest, but evaluated at each storage time. The results were submitted to ANOVA, and comparisons of means were carried out by Tukey test at 5% significance), using the program SISVAR. The parameters evaluated influenced on the quality of grains and seeds. Crop losses were lower at 12 and 4 p.m., at lower rotation speeds and cylinder displacement of the harvester. The purity of seeds was lower at 4 p.m. with a lower rotation speed intermeeting. Mechanical damage was not significant at harvest, with the variation of the parameters for collection, but may have influenced the quality parameters of grain and seeds. There was a gradual increase in the percentage of germination of bean seeds during storage, and there may be an inverse relationship with water content. Damage occurred during harvesting may have influenced the increase of cooking time and reduced water absorption, since there were differences of these parameters within each storage time. No relationship was observed between percentage of water absorption in the grain and cooking time, given that little variation in the first parameter was observed during storage, unlike the cooking time, in which the changes were remarkable / Com a expansão da cultura do feijão, a colheita mecanizada vem se tornando cada vez mais necessária, devido tanto à escassez de mão de obra, quanto ao aumento do rendimento da colheita. Por isso, torna-se indispensável o conhecimento das variáveis envolvidas nessa operação. Assim, dentro deste contexto, o objetivo do presente trabalho é avaliar alterações na qualidade de sementes e grãos de feijão comum, armazenados em função de parâmetros de colheita mecanizada. O experimento foi desenvolvido em área comercial no município de Santa Tereza do Oeste Paraná, utilizando-se, para colheita o feijão IAPAR 81, colhedora automotriz, com kit feijão e cilindro axial (adaptado). A cultura foi implantada no ano agrícola 2009/2010, utilizando espaçamento entre linhas de 0,45 m e 14 plantas m-1 e as práticas culturais foram aplicadas visando ao controle de insetos, doenças e plantas invasoras. Para a colheita, foram testados horários de colheita (8, 12 e 16 h), rotações de cilindro (300, 340 e 385 rpm) e velocidades de deslocamento da colhedora (4, 5 e 6 km h-1). Foram avaliados teor de água, pureza, perdas e danos nas sementes, além da porcentagem de germinação. Os grãos ou sementes, colhidas foram armazenados e as avaliações realizadas aos 0 (controle), 45, 90 e 180 dias. Para a avaliação da qualidade tecnológica foram realizados os testes do tempo de cozimento, absorção de água antes do cozimento, além da avaliação da germinação, teor de água, massa de 100 sementes. O experimento foi conduzido em delineamento inteiramente casualizado e em esquema de parcela sub-sub dividida (3 x 3 x 3- horários de colheita, velocidades de deslocamento e rotação do cilindro) com quatro repetições e para o armazenamento foi o mesmo esquema da análise na colheita, porém avaliado em cada tempo de armazenamento. Os resultados foram submetidos à ANOVA, e comparação de médias pelo Teste de Tukey a 5% de significância), utilizando-se o programa SISVAR. Os parâmetros de colheita avaliados influenciam na qualidade dos grãos e das sementes. As perdas na colheita foram menores nos horários das 12 e 16 h, nas menores rotações de cilindro e velocidades de deslocamento da colhedora. A pureza das sementes foi menor às 16 h com menor rotação na velocidade intermediária. Os danos mecânicos não foram significativos no momento da colheita, com a variação dos parâmetros de colheita, mas podem ter influenciado nos parâmetros de qualidade de grãos e sementes. Ocorreu aumento gradativo da porcentagem de germinação das sementes de feijão com o armazenamento, podendo haver relação inversa com o teor de água. Danos ocorridos durante a colheita podem ter influenciado no aumento de tempo de cozimento e na redução da absorção de água, uma vez que houveram diferenças desses parâmetros dentro de cada tempo de armazenamento. Não se observou relação entre porcentagens de absorção de água nos grãos e o tempo de cozimento dos mesmos, uma vez que pouca variação do primeiro parâmetro foi observada com o armazenamento, diferente do tempo de cozimento, no qual as variações foram marcantes
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Introduction to Critical Strain and a New Method for the Assessment of Mechanical Damage in Steel Line PipeMilligan, Ryan 16 December 2013 (has links)
The pipeline industry has conducted a vast amount of research on the subject of mechanical damage. Mechanical damage makes up a large portion of the total amount of pipeline failures that occur each year. The current methods rely on engineering judgment and experience rather than scientific theory. The method for the assessment of mechanical damage introduced in this study uses a material property called critical strain to predict the onset of cracking within the pipe wall. The critical strain is compared to the strain within a dent using a ductile failure damage indicator (DFDI).
To investigate the use of the DFDI to indicate the onset of cracking within a dent, the study attempted to accomplish three tasks. The first was to investigate the use of various techniques to locate the critical strain from the stress-strain curve. Five samples taken from the pipe material was used to generate both engineering and true stress-strain curves. A sensitivity analysis was conducted to show the effects of different variables on the critical strain value.
The DFDI compares the critical strain value to the calculated strain at the deepest depth location within a dent. The strain calculations use the curvature of the dent and thus require a dent profile. A high resolution laser scanner was used to extract dent profiles from a pipe. The second task of the study was to investigate the reliability of the laser scanner equipment used for this study. The results from the investigation showed that the laser scanner could be used to scan the inside of the pipe despite its design for external scanning. The results also showed that the scans should be 1 mm in length along the axis of the pipe at a resolution of 0.5 mm and 360 degrees around the pipe.
The final task was to conduct the denting test. The test used a spherical indenter to dent the pipe at increments of 3% of the outside diameter. The results from the test showed that a visible crack did not form on the inside pipe surface as expected from the DFDI method. This does not mean a crack did not form. During the denting test distinct popping sounds were observed possibly indicating cracks forming within the pipe wall.
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Avaliação de camadas de proteção para geomembranas de PVC e PEAD / Assessment of the performance of protective layers for PVC and HDPE geomembranesKarla Maria Wingler Rebelo 03 February 2009 (has links)
O presente trabalho investiga o desempenho de geotêxteis e de solos como elementos de proteção para geomembranas de polivinil clorado (PVC) e de polietileno de alta densidade (PEAD). Foram utilizadas geomembranas de PVC com espessuras de 1,0 e 2,0 mm e de PEAD com espessuras de 1,5 e 2,0 mm. Como camadas de proteção utilizaram-se geotêxteis não tecidos de poliéster (PET), com gramaturas de 130, 300, 400 e 600 g/\'M POT.2\', e de polipropileno (PP), com gramatura de 400 e 600 g/\'M POT.2\', além de uma areia de granulometria fina a média e uma areia argilosa típica da região Centro-Oeste do Estado de São Paulo. O estudo foi conduzido através da construção de um aterro experimental para simulação dos danos de instalação em campo e da realização de ensaios índice e de desempenho em laboratório. A eficiência dos materiais de proteção foi avaliada através da análise qualitativa e quantitativa das amostras de geomembranas danificadas. Os resultados dos ensaios de laboratório índice mostraram que a introdução do geotêxtil aumenta a resistência à punção da geomembrana, e que o acréscimo de resistência é função das características de resistência à tração do geotêxtil e da geomembrana. O maior incremento de resistência à punção foi observado na geomembrana com menor resistência à tração. Os resultados dos ensaios de campo mostraram que a introdução do elemento de proteção reduz os danos mecânicos apesar da alteração de algumas das propriedades físicas e de desempenho nas geomembranas. Da análise dos resultados, verificou-se que a eficiência dos geotêxteis no campo não é função de suas características de tração, conforme constatado nos ensaios índices. A análise também sugere que os danos mecânicos no campo foram mais intensos do que nos ensaios de desempenho em laboratório. / The performance of non-woven geotextiles and soils as protection elements of polyvinyl chloride (PVC) and high density polyethylene (HDPE) geomembranes is studied. The materials used comprised PVC geomembranes of 1,0 and 2,0 mm thickness and HDPE geomembranes of 1,5 and 2,0 mm thickness while the protective layers were of non-woven polyester (PET) geotextiles with mass per unit area of 130, 300, 400 e 600 g/\'M POT.2\' and polypropylene (PP) with mass per unit area of 400 e 600 g/\'M POT.2\'. It was also used protective layers made of a fine to medium sand and a typical clayey sand of central area of the State of São Paulo. The study was based on an experimental landfill built to simulate the damage associated to construction procedures and on index and performance laboratory tests. Through qualitative and quantitative analysis of damaged geomembranes, the behavior of each protective element was evaluated. Index laboratory test results have shown that the geotextile is able to increase the geomembrane puncture strength and that the strength increase is related to the tensile strength of geotextile and geomembrane. For similar geotextiles, the larger increase in puncture strength was observed for the geomembrane that presented the lower tensile strength. Visual observation of field tests has shown that the introduction of protective layers reduces the mechanical damage; however some physical and performance properties of geomembrane have changed. It was also observed that the performance of geotextiles in the experimental landfill does not depend on the tensile strength, as observed in laboratory index tests. Test results also suggest that field damage associated to the landfill construction are more intense than that observed in laboratory tests such as the dynamic puncture test.
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