930 resultados para CFRP bars
Resumo:
Purpose: To build a model that will predict the survival time for patients that were treated with stereotactic radiosurgery for brain metastases using support vector machine (SVM) regression.
Methods and Materials: This study utilized data from 481 patients, which were equally divided into training and validation datasets randomly. The SVM model used a Gaussian RBF function, along with various parameters, such as the size of the epsilon insensitive region and the cost parameter (C) that are used to control the amount of error tolerated by the model. The predictor variables for the SVM model consisted of the actual survival time of the patient, the number of brain metastases, the graded prognostic assessment (GPA) and Karnofsky Performance Scale (KPS) scores, prescription dose, and the largest planning target volume (PTV). The response of the model is the survival time of the patient. The resulting survival time predictions were analyzed against the actual survival times by single parameter classification and two-parameter classification. The predicted mean survival times within each classification were compared with the actual values to obtain the confidence interval associated with the model’s predictions. In addition to visualizing the data on plots using the means and error bars, the correlation coefficients between the actual and predicted means of the survival times were calculated during each step of the classification.
Results: The number of metastases and KPS scores, were consistently shown to be the strongest predictors in the single parameter classification, and were subsequently used as first classifiers in the two-parameter classification. When the survival times were analyzed with the number of metastases as the first classifier, the best correlation was obtained for patients with 3 metastases, while patients with 4 or 5 metastases had significantly worse results. When the KPS score was used as the first classifier, patients with a KPS score of 60 and 90/100 had similar strong correlation results. These mixed results are likely due to the limited data available for patients with more than 3 metastases or KPS scores of 60 or less.
Conclusions: The number of metastases and the KPS score both showed to be strong predictors of patient survival time. The model was less accurate for patients with more metastases and certain KPS scores due to the lack of training data.
Resumo:
Pipelines are one of the safest means to transport crude oil, but are not spill-free. This is of concern in North America, due to the large volumes of crude oil shipped by Canadian producers and the lengthy network of pipelines. Each pipeline crosses many rivers, supporting a wide variety of human activities, and rich aquatic life. However, there is a knowledge gap on the risks of contamination of river beds due to oil spills. This thesis addresses this knowledge gap by focussing on mechanisms that transport water (and contaminants) from the free surface flow to the bed sediments, and vice-versa. The work focuses on gravel rivers, in which bed sediments are sufficiently permeable that pressure gradients caused by the interactions of flow with topographic elements (gravel bars), or changes in direction induce exchanges of water between the free surface flow and the bed, known as hyporheic flows. The objectives of the thesis are: to present a new method to visualize and quantify hyporheic flows in laboratory experiments; to conduct a novel series of experiments on hyporheic flow induced by a gravel bar under different free surface flows. The new method to quantify hyporheic flows rests on injections of a solution of dye and water. The method yielded accurate flow lines, and reasonable estimates of the hyporheic flow velocities. The present series of experiments was carried out in a 11 m long, 0.39 m wide, and 0.41 m deep tilting flume. The gravel had a mean particle size of 7.7 mm. Different free surface flows were imposed by changing the flume slope and flow depth. Measured hyporheic flows were turbulent. Smaller free surface flow depths resulted in stronger hyporheic flows (higher velocities, and deeper dye penetration into the sediment). A significant finding is that different free surface flows (different velocities, Reynolds number, etc.) produce similar hyporheic flows as long as the downstream hydraulic gradients are similar. This suggests, that for a specified bar geometry, the characteristics of the hyporheic flows depend on the downstream hydraulic gradients, and not or only minimally on the internal dynamics of the free surface flow.
Resumo:
The study of the Upper Jurassic-Lower Cretaceous deposits (Higueruelas, Villar del Arzobispo and Aldea de Cortés Formations) of the South Iberian Basin (NW Valencia, Spain) reveals new stratigraphic and sedimentological data, which have significant implications on the stratigraphic framework, depositional environments and age of these units. The Higueruelas Fm was deposited in a mid-inner carbonate platform where oncolitic bars migrated by the action of storms and where oncoid production progressively decreased towards the uppermost part of the unit. The overlying Villar del Arzobispo Fm has been traditionally interpreted as an inner platform-lagoon evolving into a tidal-flat. Here it is interpreted as an inner-carbonate platform affected by storms, where oolitic shoals protected a lagoon, which had siliciclastic inputs from the continent. The Aldea de Cortés Fm has been previously interpreted as a lagoon surrounded by tidal-flats and fluvial-deltaic plains. Here it is reinterpreted as a coastal wetland where siliciclastic muddy deposits interacted with shallow fresh to marine water bodies, aeolian dunes and continental siliciclastic inputs. The contact between the Higueruelas and Villar del Arzobispo Fms, classically defined as gradual, is also interpreted here as rapid. More importantly, the contact between the Villar del Arzobispo and Aldea de Cortés Fms, previously considered as unconformable, is here interpreted as gradual. The presence of Alveosepta in the Villar del Arzobispo Fm suggests that at least part of this unit is Kimmeridgian, unlike the previously assigned Late Tithonian-Middle Berriasian age. Consequently, the underlying Higueruelas Fm, previously considered Tithonian, should not be younger than Kimmeridgian. Accordingly, sedimentation of the Aldea de Cortés Fm, previously considered Valangian-Hauterivian, probably started during the Tithonian and it may be considered part of the regressive trend of the Late Jurassic-Early Cretaceous cycle. This is consistent with the dinosaur faunas, typically Jurassic, described in the Villar del Arzobispo and Aldea de Cortés Fms.
Resumo:
Mallorca, the largest of the Balearic Islands, is a well-known summer holidays destination; an ideal place to relax and enjoy the sun and the sea. That tourist gaze reflected on postcards results from advertising campaigns, where cinema played an important role with documentaries and fiction films. The origins of that iconography started in the decades of the 1920’s and 1930’s, reflecting the so-called myth of the “island of calm”. On the other hand, the films of the 1950’s and 1960’s created new stereotypes related to the mass tourism boom. Busy beaches and the white bodies of tourists replaced white sandy beaches, mountains and landscapes shown up in the movies of the early decades of the 20th century. Besides, hotels and nightclubs also replaced monuments, rural landscapes and folk exhibitions. These tourist images mirror the social and spatial transformations of Mallorca, under standardization processes like other seaside mass tourist destinations. The identity was rebuilt on the foundations of "modernity". Although "balearization" has not ceased, nowadays filmmaking about Mallorca is advertising again a stereotype close to that one of the 1920s and 1930s, glorifying the myth of the "island of calm". This singular identity makes the island more profitable for capital that searches socio-spatial differentiation in post-fordist times.
Resumo:
Carbon fibre reinforced polymers (CFRP) are increasingly being used in the aerospace, automotive and defence industry due to their high specific stiffness and good corrosion resistance. In a modern aircraft, 50-60% of its structure is made up of CFRP material while the remainder is mostly a combination of metallic alloys (typically aluminium or titanium alloys). Mechanical fastening (bolting or riveting) of CFRP and metallic components has thus created a pressing requirement of drilling several thousand holes per aircraft. Drilling of stacks in a single-shot not only saves time, but also ensures proper alignment when fasteners are inserted, achieving tighter geometric tolerances. However, this requirement poses formidable manufacturing challenges due to the fundamental differences in the material properties of CFRP and metals e.g. a drill bit entering into the stack encounters brittle and abrasive CFRP material as well as the plastic behaviour of the metallic alloy, making the drilling process highly non-linear.
Over the past few years substantial efforts have been made in this direction and majority of the research has tried to establish links between how the process parameters (feed, depth of cut, cutting speed), tooling (geometry, material and coating) and the wear of the cutting tool affect the hole quality. Similarly, multitudes of investigations have been conducted to determine the effects of non-traditional drilling methods (orbital, helical and vibration assisted drilling), cutting zone temperatures and efficiency of chip extraction on the hole quality and rate of tool wear during single shot drilling of CFRP/alloy stacks.
In a timely effort, this paper aims at reviewing the manufacturing challenges and barriers faced when drilling CFRP/alloy stacks and to summarise various factors influencing the drilling process while detailing the advances made in this fertile research area of single-shot drilling of stack materials. A survey of the key challenges associated with avoiding workpiece damage and the effect these challenges have on tool design and process optimisation is presented. An in depth critique of suitable hole making methods and their aptness for commercialisation follows. The paper concludes by summarising the future work required to achieve repeatable, high quality single shot drilled holes in CFRP/alloy stacks.
Resumo:
Pregnant women and mothers were among the thousands of individuals who were sentenced to at least three years’ penal servitude and admitted to the nineteenth-century Irish female convict prison. While some babies were born behind bars, others were permitted to accompany their convicted mothers into the prison after the penal practice of transportation had ceased. Other dependent children were separated from their convicted mothers for years, cared for by family members or friends, or accommodated in Ireland’s growing web of institutions. Using individual case studies, this article focuses on convict mothers and their young offspring. It draws attention to the increasing restrictions on the admission of infants that were imposed as the nineteenth century progressed, the problems that children of various ages in the penal system seemed to pose for officials, and the difficulties faced by incarcerated mothers who wished to maintain communication with their offspring. This article argues that while there were benefits to parenting within the confines of the prison, sentences of penal servitude had a significant impact on the lives of dependent offspring by dislocating families, separating siblings, or initiating institutional or other care that broke familial bonds permanently. In so doing, the article reveals attitudes towards motherhood as well as female criminality and institutionalization generally during this period and sheds light on an aspect of convict life unique to the women’s prison.
Resumo:
A second-season makeover at the 1964-1965 New York World's Fair. Hoping that "an interesting controversy" would revive the state of Minnesota's failing pavilion, Minnesota adds a large fiberglass Viking, longboat-styled snack bars, and the contested Kensington Runestone itself to its 'Brainpower Builds Profits' exhibit. [abstract adapted from Minnesota History 63/1]
Resumo:
A presente dissertação incide sobre o estudo dos efeitos do confinamento com materiais compósitos de polímeros reforçados com fibras de carbono (CFRP) em pilares de estruturas de betão armado. A motivação para este estudo surge da necessidade de aprofundar conhecimentos acerca do comportamento dos pilares de betão reforçados por confinamento com CFRP, uma vez que a sua aplicação apresenta uma crescente importância, por exemplo, para aumento da resistência e da ductilidade de estruturas de betão armado. Fez-se, inicialmente, uma breve revisão das técnicas de reforço convencionais utilizadas em pilares de betão armado, com ênfase no reforço exterior com polímeros reforçados com fibras. A elevada resistência à tração, à corrosão e à fadiga, o baixo peso volúmico, a versatilidade e a diversidade dos sistemas comercializados com CFRP tornam este material muito competitivo para este tipo de aplicação. Na sequência desse estudo, realizou-se uma revisão bibliográfica acerca dos modelos de comportamento que permitem prever o desempenho de pilares de betão confinados com CFRP, sujeitos a esforços de compressão. Como forma de análise desses modelos, desenvolveu-se uma ferramenta numérica em ambiente Mathworks - Matlab R2015a, que permitiu a obtenção e posterior comparação dos diagramas de tensão-extensão descritos pelos modelos desenvolvidos por Manfredi e Realfonzo (2001), Ferreira (2007) e Wei e Wu (2011). Por fim, comparam-se os resultados experimentais de Paula (2003) e de Rocca (2007) com os dos modelos constitutivos referidos anteriormente, analisando-se também a influência de vários fatores na eficácia do confinamento, tais como o boleamento, o número de camadas de CFRP e a geometria da secção transversal. Foram ainda comparados e discutidos resultados relativos ao confinamento parcial de pilares. Os resultados obtidos indicam que os modelos analíticos representam relativamente bem o andamento das curvas do betão confinado para secções circulares, quadradas e retangulares, verificando-se as principais discrepâncias nestas duas últimas tipologias de secção transversal, dada a dificuldade associada à quantificação de parâmetros associados ao seu comportamento (por exemplo, boleamento de arestas). No entanto, verificou-se igualmente que com um adequado boleamento de arestas (e consequente aumento da relação entre o raio de canto e a largura da secção de betão), bem como com um aumento do número de camadas de material compósito, é possível aumentar a tensão resistente e a extensão axial na rotura do betão à compressão.
Resumo:
The low-strength concrete is defined as a concrete where the compressive cubic strength is less than 15 MPa. Since the beginning of the last century, many low-strength concrete buildings and bridges have been built all over the world. Being short of deeper study, composite sheets are prohibited in strengthening of low-strength reinforced concrete members (CECS 146; ACI 440). Moreover, there are few relevant information about the long-term behavior and durability of strengthened RC members. This fact undoubtedly limits the use of the composite materials in the strengthening applications, therefore, it is necessary to study the behaviours of low-strength concrete elements strengthened with composite materials (FRP) for the preservation of historic constructions and innovation in the strengthening technology. Deformability is one of criteria in the design of concrete structures, and this for functionality, durability and aesthetics reasons. Civil engineer possibly encounters more deflection problems in the structural design than any other type of problem. Many materials common in structural engineering such as wood, concrete and composite materials, suffer creep; if the creep phenomenon is taken into account, checks for serviceability limit state criteria can become onerous, because the creep deformation in these materials is in the same order of magnitude as the elastic deformation. The thesis presents the results of an experimental study on the long-term behavior of low-strength reinforced concrete beams strengthened with carbon fiber composite sheets (CFRP). The work has investigated the accuracy of the long-term deflection predictions made by some analytical procedures existing in literature, as well as by the most widely used design codes (Eurocode 2, ACI-318, ACI-435).
Resumo:
The technical, environmental and economic potential of hemp fines as a natural filler in bioplastics to produce biocomposites is the subject of this study – giving a holistic overview. Hemp fines are an agricultural by-product of the hemp fibres and shives production. Shives and fibres are for example used in the paper, animal bedding or composite area. About 15 to 20 wt.-% per kg hemp straw results in hemp fines after processing. In 2010 about 11,439 metric tons of hemp fines were produced in Europe. Hemp fines are an inhomogeneous material which includes hemp dust, shives and fibre. For these examinations the hemp fines are sieved in a further step with a tumbler sieving machine to obtain more specified fractions. The untreated hemp fines (ex work) as well as the sieved fractions are combined with a polylactide polymer (PLA) using a co-rotating twin screw extruder to produce biocomposites with different hemp fine content. By using an injection moulding machine standard test bars are produced to conduct several material tests. The Young’s modulus is increased and the impact strength reduced by hemp fines. With a content of above 15 wt.-% hemp fines are also improving the environmental (global warming potential) and economic performance in comparison to pure PLA.
Resumo:
Cette thèse propose une lecture anthropologique de la consommation d’alcool. Elle met de l’avant une approche novatrice qui repose sur le concept de « métaphysique du quasi- arrêt ». Cette approche a été développée à la suite d’une recherche ethnographique réalisée dans la région de la Beauce, au Québec. Au lieu de considérer la consommation d’alcool comme un problème social ou de santé publique, j’ai cherché à comprendre comment et pourquoi l’on boit, en Beauce, en me laissant guider par les buveurs et les buveuses côtoyés sur place. En prenant part à de nombreuses soirées où la bière est omniprésente, que ce soit dans les garages, les bars ou l’aréna local, je me suis laissé affecter par les sensations ressenties et par les paroles prononcées lorsque les buveurs éprouvent ce qu’ils appellent le « feeling du moment ». En prenant du recul, j’ai constaté que les Beaucerons qui boivent ont développé des stratégies défensives pour échapper à la tentative de contrôle de la société québécoise sur leurs conduites alcooliques et, plus largement, sur l’alcoolisme. En effet, dans la perspective de la « métaphysique du quasi-arrêt », la quantité de verres consommés n’a d’importance qu’eu égard au « feeling du moment »; les normes culturelles ou médicales liées à la consommation d’alcool ne tiennent pas, et c’est pourquoi cette approche permet d’expliquer des discours et des pratiques liés à la consommation d’alcool qui, à première vue, semblent paradoxaux, voire complètement absurdes. Pour bien montrer en quoi l’approche mise de l’avant se distingue, mais surtout pour expliquer comment la consommation excessive d’alcool en est venue à représenter, en anthropologie comme dans d’autres disciplines, une pratique problématique qu’il faut comprendre pour la combattre, une première partie de la thèse consiste en une mise en perspective historique de l’alcoolisme en tant que concept scientifique et enjeu de société. Y sont passées en revue les approches et concepts développés, depuis la fin du XVIIe siècle, par des médecins, des psychologues, des économistes, des sociologues et des anthropologues euro-américains pour aborder ce genre de consommation. Je suggère que ces scientifiques mènent, depuis plus de deux siècles, une véritable croisade contre les « buveurs excessifs ». Collaborant avec l’État, les mouvements de tempérance et les entreprises privées, ils ont contribué à contenir les abus d’alcool en Occident. Dans la seconde partie de la thèse, l’ethnographie sert de support au déploiement de la perspective théorique développée à l’issue du travail de terrain. Il s’agit d’analyser comment les buveurs d’alcool vivent et font durer le « feeling du moment » au cours du boire social. Sur le terrain, j’ai découvert que les buveurs d’alcool ont inventé onze stratégies pour vivre et faire durer le « feeling du moment » en consommant de l’alcool avec les autres. Ces stratégies constituent une forme de résistance face à une société qui cherche à contrôler les conduites alcooliques.
Resumo:
Le dimensionnement basé sur la performance (DBP), dans une approche déterministe, caractérise les objectifs de performance par rapport aux niveaux de performance souhaités. Les objectifs de performance sont alors associés à l'état d'endommagement et au niveau de risque sismique établis. Malgré cette approche rationnelle, son application est encore difficile. De ce fait, des outils fiables pour la capture de l'évolution, de la distribution et de la quantification de l'endommagement sont nécessaires. De plus, tous les phénomènes liés à la non-linéarité (matériaux et déformations) doivent également être pris en considération. Ainsi, cette recherche montre comment la mécanique de l'endommagement pourrait contribuer à résoudre cette problématique avec une adaptation de la théorie du champ de compression modifiée et d'autres théories complémentaires. La formulation proposée adaptée pour des charges monotones, cycliques et de type pushover permet de considérer les effets non linéaires liés au cisaillement couplé avec les mécanismes de flexion et de charge axiale. Cette formulation est spécialement appliquée à l'analyse non linéaire des éléments structuraux en béton soumis aux effets de cisaillement non égligeables. Cette nouvelle approche mise en œuvre dans EfiCoS (programme d'éléments finis basé sur la mécanique de l'endommagement), y compris les critères de modélisation, sont également présentés ici. Des calibrations de cette nouvelle approche en comparant les prédictions avec des données expérimentales ont été réalisées pour les murs de refend en béton armé ainsi que pour des poutres et des piliers de pont où les effets de cisaillement doivent être pris en considération. Cette nouvelle version améliorée du logiciel EFiCoS a démontrée être capable d'évaluer avec précision les paramètres associés à la performance globale tels que les déplacements, la résistance du système, les effets liés à la réponse cyclique et la quantification, l'évolution et la distribution de l'endommagement. Des résultats remarquables ont également été obtenus en référence à la détection appropriée des états limites d'ingénierie tels que la fissuration, les déformations unitaires, l'éclatement de l'enrobage, l'écrasement du noyau, la plastification locale des barres d'armature et la dégradation du système, entre autres. Comme un outil pratique d'application du DBP, des relations entre les indices d'endommagement prédits et les niveaux de performance ont été obtenus et exprimés sous forme de graphiques et de tableaux. Ces graphiques ont été développés en fonction du déplacement relatif et de la ductilité de déplacement. Un tableau particulier a été développé pour relier les états limites d'ingénierie, l'endommagement, le déplacement relatif et les niveaux de performance traditionnels. Les résultats ont démontré une excellente correspondance avec les données expérimentales, faisant de la formulation proposée et de la nouvelle version d'EfiCoS des outils puissants pour l'application de la méthodologie du DBP, dans une approche déterministe.
Resumo:
Brazil has a great diversity of native fruits, which are not always widely consumed, being sold only in certain regions, due to their difficulty of post-harvest conservation. One such fruit is yellow guava, interesting source of nutrients. To promote the consumption and use of this fruit to the consumer public in different regions of the country, this study evaluated the incorporation of yellow Ya-cy araçá in formulating a cereal bar. Therefore, fruits were evaluated for their chemical, physical and chemical characteristics and bioactive compounds in different stages of maturation yellow guava (green, mature and dried forms). The behavior of guava yellow front of to UV-C radiation was also evaluated. After these reviews, there was obtained yellow ripe guava flour after previous tests, was added to the base formulation cereal bar. For the experimental planning and development of the formulations was used factorial design 22 with a central point. The developed formulations were subjected to sensory evaluation using for treatment of multivariate data analysis (Principal Component Analysis- ACP). The preferred formulation in sensory evaluation was evaluated in their physical characteristics (texture), physical-chemical (moisture, ash, lipids, proteins, carbohydrates, dietary fiber and calorie), mineral content and fatty acid profile. The results indicated that the added yellow guava cereal bar developed in this study is one way to application and use of guava, increasing the consumption of fruit to different regions of the country, and can be considered a functional product, not only to contain the fruit in its composition, but also to present many beneficial nutrients that contribute to the health of consumers.
Resumo:
The objective of this study was to evaluate different binders when preparing salt cereal bars and to characterize them as physical, physico-chemical and sensory parameters. Four formulations of different cereal bars using binders have been developed. The evaluated binders were collagen, guar gum, xanthan gum and psyllium. The developed cereal bars were evaluated according to their physical characteristics (color and texture), physicochemical (pH, moisture, ash, protein, lipids, Aw, crude fiber) beyond their calorie, fatty acid composition and concentration of the main minerals. Among the four binding agents evaluated, psyllium stood out due to its physicochemical characteristics. A cereal bar high in protein and fiber; low in carbohydrates and water activity. The binding agent guar gum and xanthan showed characteristics similar to psyllium, especially regarding to fiber content. Collagen as binder gave the final product a high level in protein and lipid. The color and texture analyzes showed that the salt cereal bars had the color and crispness characteristics for this type of product. Regarding to the composition in the fatty acid, the developed bars offer a good supply of essential fatty acids to the human body. The same was observed regarding to mineral contents. Sensory, salt cereal bars made with chia showed good acceptability, highlighting the elaborate bar with psyllium binder. Different binders demonstrated technological efficiency in the preparation of salt cereal bars. The binder psyllium agent over others showed better physical-chemical and sensory characteristics. However, in general the product has healthy and nutritional characteristics it may be indicated for a protein diet with high fiber content and free sugars.
Resumo:
O contínuo crescimento da população mundial aumenta a demanda e a competição por energia, colocando grande esforço sobre as fontes de energia não renováveis existentes. Devido a isso, políticas globais para geração de energias renováveis e menos poluentes estão sendo fortalecidas, além de promoverem o desenvolvimento de novas tecnologias. Várias formas de conversão de energia foram desenvolvidas no decorrer dos anos, com destaque para os conversores de energia das correntes a base de turbinas, que demonstram alta capacidade de conversão energética e já se encontram em funcionamento. O modelo tridimensional TELEMAC3D foi utilizado para a investigação dos processos hidrodinâmicos. Este modelo foi acoplado ao módulo de conversão de energia para as análises nos locais de maior viabilidade e conversão energética na Plataforma Continental do Sul do Brasil. A região de estudo demonstrou possuir duas regiões com alto potencial para a exploração da energias das correntes marinhas, entretanto a região mais viável para a instalação de conversores de corrente é a região norte delimitada entre o Farol da Conceição e o Farol da Solidão, podendo atingir potência média de 10kW=Dia, e alcançando valores integrados de 3:5MW=Ano. Através de uma análise da sazonalidade foram observados, durante a primavera os períodos mais energéticos em ambas as regiões estudadas. As maiores intensidades de conversão de energia foram estimadas com variabilidade temporal de 16 dias, demonstrando alta correlação com eventos associados à passagem de frentes meteorológicas na região. O sítio da região norte, com a presença de barreiras que representam a forma dos conversores, se destaca mantendo boa conversão durante os eventos de ótimo potencial energético. Esta melhora se deve ao efeito de intensificação do campo de correntes associado à presença da estrutura física que otimiza a eficiência do sítio. Não foram observadas diferenças significativas no padrão de variabilidade temporal das simulações estudadas, indicando que a presença das barreiras não induz grandes alterações no padrão temporal da conversão de energia nas escalas temporais analisadas neste trabalho. Os eventos de alta geração de energia foram relacionados a incidência de fortes ventos de quadrante sul e norte, indicando que pelo formato e disposição dos conversores, ventos de sudoeste e norte podem favorecer ótimos eventos de conversão de energia. As simulações dos sítios de conversão demonstraram alta capacidade de geração energética, com quatro eventos de extrema geração de energia. Entretanto, o sítio da região norte demonstrou eficiência superior a 59,39 GWh ao ano, equivalendo a 0.22% do consumo energético do estado do Rio Grande do Sul no ano de 2010.