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1
O'Brien, William John. "Characterisation and material removal properties of the RAP™ process." Thesis, Cranfield University, 2011. http://dspace.lib.cranfield.ac.uk/handle/1826/6560.
Abstract:
The Reactive Atom Plasma® (RAP) process is a plasma chemical etching process. RAP was developed at RAPT Industries as a process for removing subsurface damage from silicon carbide optics. The process is being investigated at Cranfield University as a novel method for the fine surface correction of large optics, with the aim of shortening the manufacturing period of the next generation of large telescopes. RAP offers material removal rates that are up to 10 times higher than those of ion beam figuring, the current state-of-the-art technique and the convenience in that it can be operated at atmospheric pressure. Cont/d.
2
Penny, Julie Elizabeth. "An evaluation of heated reclaimed asphalt pavement (RAP) material and wax modified asphalt for use in recycled hot mix asphalt (HMA)." Worcester, Mass. : Worcester Polytechnic Institute, 2007. http://www.wpi.edu/Pubs/ETD/Available/etd-010807-113145/.
3
Forton, Andrei-Roman. "Thermomechanical behaviour of bituminous materials including RAP and rejuvenator and environmental impact of their fabrication process." Electronic Thesis or Diss., Lyon, 2021. http://www.theses.fr/2021LYSET005.
Abstract:
L'étude présentée dans cette thèse a été réalisée dans le cadre d'une collaboration entre l'Université Polytechnique de Timisoara (UPT, Universitatea Politehnica Timisoara) de Roumanie et l'Université de Lyon / ENTPE en France. Les objectifs sont, i) la caractérisation des performances thermomécaniques des mélanges de liants et des enrobés bitumineux produits à partir d’agrégats d’enrobés (RAP) et de réjuvénant et, ii) l'étude de l'impact environnemental lié à la production d'un mélange contenant différentes quantités de matériaux RAP et de réjuvénant. Des études expérimentales poussées ont été réalisées sur les liants d’une part, et sur les enrobés, d’autre part. Tous les essais sur les liants et les enrobés ainsi que l'évaluation de l'impact environnemental ont été réalisés à l'UPT. Les analyses et la modélisation de la plupart des paramètres / caractéristiques des liants et des enrobés ont été effectuées au laboratoire LTDS de l'ENTPE. L'étude sur les liants s'est concentrée sur les propriétés de liants produits en mélangeant un liant pur (50/70 pen.), un liant extrait du RAP, et un réjuvénant d'origine végétale. L'étude sur les enrobés s'est concentrée sur l'investigation de 13 enrobés bitumineux produits avec différentes quantités de matériau RAP, et avec ou sans réjuvénant. Le liant pur, le liant du RAP et le réjuvénant utilisés dans les enrobés, ainsi que leurs proportions, sont les mêmes que celles utilisées pour la campagne expérimentale sur les mélanges de liants. Une analyse de l'impact environnemental (EIA) a été réalisée afin d'estimer l'impact environnemental potentiel lié au processus de fabrication des enrobés bitumineux considérésThe study presented in this thesis has been carried out within a collaboration between Politehnica University Timisoara (UPT) from Romania and Université de Lyon/École Nationale des Travaux Publics de l'État (ENTPE), laboratory LTDS from France. The objectives are, i) the characterization of the thermomechanical performances of binder blends and bituminous mixtures produced with Reclaimed Asphalt Pavement (RAP) and rejuvenator and, ii) the investigation of the potential environmental impact related to the production of a mixture containing different amounts of RAP material and rejuvenator. Therefore, comprehensive experimental investigations were performed on binders and mixtures. All tests on binders and mixtures were performed in the Road Laboratory from UPT, together with the environmental impact assessment. On the other hand, the analyses, estimations and predictions of most parameters/characteristics of binders and mixtures were performed at ENTPE. The study on binders focused on the properties of different binder blends produced by mixing one type of fresh binder (a straight run 50/70 pen. grade), a RAP-extracted binder and a rejuvenator of vegetal origin. The study on mixtures focused on the investigation on 13 bituminous mixtures
4
Tanski, Mateus Camargo. "COMPORTAMENTO MECÂNICO DE MATERIAL RECICLADO A FRIO COM EMULSÃO E CIMENTO." Universidade Federal de Santa Maria, 2016. http://repositorio.ufsm.br/handle/1/7934.
Abstract:
The recycled asphalt pavement (RAP) extracted from recovery distresses in highways does not receive the attention and importance it deserves in Brazil. The reuse of this material, which presents as good properties as the virgin aggregate, when applied correctly in the composition of new pavement layers or rehabilitations, is a widely used in European and United States. Besides solving the environmental liabilities of pavement, the reuse of milled material in asphalt mixtures is a sustainable alternative, which decreases consumption of asphalt and virgin aggregate, milled material transportation and allocation costs. This study seeks an alternative to the use of RAP as the base layer in the implementation of new pavements.For this paper, cold recycled mixtures were studied, wich are composed of RAP (granulometrically stabilized with fine aggregate) and RL-1C asphalt emulsion, a bituminous binder that contains added Portland Cement (CP V ARI) in the proportions of 2% to 5% for emulsion and from 0% to 1% of cement, in weight. The proposed mixtures were evaluate through mechanical resistance to single compression (RCS), indirect tensile strength (RT), resilient modulus tests (RM), Complex Modulus (E* and Ф) and Flow Number (FN). After performing these tests, it was observed that the values obtained reveal that the mixtures with proportions varying from 50% to 75% of emulsion, compared to the cement used in the mixtures, show better results. Moreover, the mixtures present resilient modulus results ranging from 1500 MPa to 3000 MPa (excellent values for base layers). The FN test shows that by adding cement to the mixture, the results improved in the form of an increment in the number of cycles, which performed at its best with samples that had 2% and 3% of emulsion. The uniaxial Complex Modulus test allowed access the viscoelastic behavior and the 2S2P1D modeling was used too. It´s possible to confirm that this technique is viable pavement maintenance.O material fresado extraído de trechos em recuperação não recebe a atenção e importância que merece no Brasil. O reaproveitamento desse material, que apresenta comportamento tão bom quanto os agregados virgens, quando empregado de maneira correta na composição de camadas de pavimentos novos ou restaurações, é uma prática largamente utilizada em países europeus e nos Estados Unidos. Além de resolver o passivo ambiental das empresas, o reemprego do fresado em misturas asfálticas, é uma alternativa sustentável que diminui o consumo de agregados virgens e custos com transporte de fresado e alocação do mesmo. Este trabalho busca uma alternativa para emprego do material fresado como camada de base na execução de pavimentos novos. Foram estudadas misturas recicladas a frio compostas de fresado estabilizado granulometricamente com pó-de-pedra e tendo como ligante betuminoso emulsão asfáltica RL-1C nas proporções de 2% a 5% e de ligante hidráulico CP V ARI de 0% a 1% de cimento. As misturas propostas foram avaliadas por meio de ensaios de resistência à compressão simples (RCS), ruptura por tração por compressão diametral (RT), módulo de resiliência (MR), módulo complexo (IE*I) e FlowNumber (FN). Após a realização dos ensaios, observou-se que os valores obtidos demonstram que as misturas com proporção variando de 50% a 75% de emulsão, em relação ao cimento empregado nas misturas, apresentam melhores resultados. Além disso, as mesmas misturas apresentam valores de módulo resiliente variando entre 1500 MPa e 3000 MPa (valores excelentes para camadas de base). O ensaio de FN mostrou que a adição de cimento na mistura melhora os resultados aumentando o número de ciclos, apresentando como melhores as amostras com 2% e 3% de emulsão. Através do ensaio de módulo dinâmico obteve-se a curva mestra das misturas utilizando a modelo 2S2P1D. Acredita-se que esta será uma alternativa técnica e economicamente viável para destinação do material fresado gerado em abundância pelas obras rodoviárias.
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Centofante, Roberta. "ESTUDO LABORATORIAL DA UTILIZAÇÃO DE MATERIAL FRESADO EM MISTURAS ASFÁLTICAS RECICLADAS A QUENTE." Universidade Federal de Santa Maria, 2016. http://repositorio.ufsm.br/handle/1/7915.
Abstract:
Fundação de Amparo a Pesquisa no Estado do Rio Grande do SulThe use of recycled materials can become a constructive application with good acceptance in the road sector, and is a great contribution to the sustainability policy. In this scenario, the study of economic and sustainable techniques for execution, construction and maintenance of highways, forces a survey in which they can find alternatives to the use of materials that reduce energy consumption, taking into account also the environmental appeal. Therefore, this is an objective research on the study of a way to use, reuse, and improve the use of the recycled asphalt pavement (RAP) in hot asphalt mixtures. This is possible due to the RAP's recycling process being a viable option to replace conventional pavement materials. Then, the RAP becomes an alternative when someone wishes to improve the properties of a material, called particle size stabilization, aiming at a correct particle size and obtain a material with greater strength, efficiency and lower cost. To achieve the purpose of this study, laboratory tests were made to evaluate the mechanical properties and adhesiveness of mixtures containing 10% addition of RAP, 20% and 30%, compared to a reference mix without the RAP addition. Additionally, the initial use of the Bailey method was an important factor to the formation of the mixtures and selection of the aggregates used to Superpave methodology to design dosage strength and preparing of the samples. For mechanical evaluation were used resilient modulus tests (RM) and to review viscoelastic were used uniaxial dynamic modulus test. In addition, the indirect tensile strength tests were performed (RT) and Flow Number (FN) and damage tests induced moisture through the Modified Lottman test and wear a Cantabro abrasion, for evaluation of the properties of adhesion and cohesion of the mixtures, respectively. So after obtained these results, it was possible to make an analysis of the use of these hot mix asphalt recycling hot pavements, as well as assess how much conventional mixtures can be improved with the inclusion of recycled material, replacing virgin aggregate. Then, it was possible to infer that the mechanical evaluation showed positive results with the addition of RAP compared to a reference blend. It´s possible to reduce the new binder content between 13 and 37%. The results showed that RM stiffness and indirect tensile strength increases with RAP amount. Furthermore, the FN test results showed reductions on permanent deformation and rutting of the RAP´s mixtures. Through the master curve obtained by dynamic module, along with modeling 2S2P1D, it was found that the CAF10 mixture unexpectedly had stiffness greater than the CAF20 mixture, which has 20% more RAP than the previous.
A utilização de materiais provenientes da reciclagem pode se tornar uma aplicação construtiva com boa aceitação no setor rodoviário, além de contribuir na política de sustentabilidade. Com isso, torna-se viável o estudo de técnicas econômicas e sustentáveis para execução, construção e manutenção de rodovias, forçando uma pesquisa em que se possa encontrar alternativas para o uso de materiais que diminuam o consumo de energia, levando em conta, ainda, o apelo ambiental. Por isso, essa pesquisa se objetiva no estudo de uma maneira de utilizar, reutilizar e melhor aproveitar o material fresado em misturas asfálticas a quente. Isto se dá devido ao processo de reciclagem deste material ser uma alternativa de possível substituição aos materiais convencionais naturais de pavimentação como, por exemplo, a pedra britada. Então, o material asfáltico do pavimento deteriorado (fresado) torna-se uma das alternativas quando se deseja melhorar as propriedades de um material, denominada estabilização granulométrica, visando corrigir sua granulometria e obter um material com maior resistência, eficiência e menor custo. Para atingir o objetivo desta pesquisa, foram realizados ensaios laboratoriais que pudessem avaliar as propriedades mecânicas e de adesividade das misturas contendo 10% de adição de fresado, 20% e 30%, comparadas a uma mistura de referência sem adição de agregado reciclado. Além disso, a utilização inicial do Método Bailey foi um fator importante para a formação das misturas e seleção dos agregados, sendo utilizada a metodologia Superpave para dosagem do teor de projeto e moldagem das amostras. Para avaliação mecânica, foram usados ensaios de módulo de resiliência (MR) e, ainda, para avaliação viscoelástica, ensaio de módulo dinâmico uniaxial. Além destes, foram realizados ensaios de resistência à tração indireta (RT) e Flow Number (FN) e, também, ensaios de dano por umidade induzida, através do ensaio de Lottman Modificado, e desgaste por abrasão Cântabro, para avaliação das propriedades de adesividade e coesão das misturas, respectivamente. Assim, após obtidos estes resultados, foi possível efetuar uma análise da utilização destas misturas asfálticas na reciclagem a quente de pavimentos, bem como avaliar o quanto as misturas convencionais podem ser melhoradas com a inserção de material reciclado, em substituição ao agregado virgem. Então, foi possível concluir que a avaliação mecânica apresentou resultados positivos com a adição de fresado, quando comparados a uma mistura de referência. Os resultados de MR mostraram que a rigidez aumenta ao passo que a quantidade de fresado é maior na composição das misturas, o mesmo foi possível verificar através dos ensaios de RT, os quais apresentaram valores crescentes. Além disso, o ensaio de FN comprovou que o fresado aumenta a rigidez das misturas. Através da curva mestra obtida pelo módulo dinâmico, juntamente com a modelagem 2S2P1D, foi possível constatar que a mistura CAF10, inesperadamente, apresentou rigidez maior que a mistura CAF20, a qual tem 20% a mais de fresado que a anterior.
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Pasche, Eduardo. "Estudo da resistência e da rigidez de uma mistura de material fresado asfáltico e pó-de-pedra com a adição de cimento." reponame:Biblioteca Digital de Teses e Dissertações da UFRGS, 2016. http://hdl.handle.net/10183/149836.
Abstract:
A malha rodoviária brasileira é elemento fundamental para as cadeias produtivas, pois promove a integração de regiões, estados, portos, ferrovias, hidrovias e aeroportos. A qualidade do pavimento é um dos principais determinantes do desempenho dos usuários durante suas viagens. Uma das formas para a correção dos defeitos nos pavimentos é a restauração, sendo bastante empregada atualmente a fresagem do revestimento asfáltico, que consiste na operação de um corte do revestimento asfáltico, esta atividade produz uma grande quantidade de resíduo nas obras de restauração de rodovias, denominado de material fresado asfáltico ou somente fresado, que é constituído por agregados (graúdos e miúdos) e Cimento Asfáltico de Petróleo (CAP). Esta pesquisa objetivou avaliar, através de ensaios laboratoriais, a viabilidade da utilização de uma mistura de material fresado e pó-de-pedra estabilizados quimicamente com cimento Portland em camadas de pavimentos flexíveis, correlacionando o índice porosidade/teor volumétrico de cimento (η/Civ) com parâmetros de rigidez e resistência das misturas. O material fresado é oriundo da BR-290. Foi realizada estabilização granulométrica, sendo determinado o teor de 70% de material fresado e 30% de pó-de-pedra e a estabilização química, com os teores de 3%, 5% e 7%. Foram moldados corpos-de-prova de 10 x 20 cm para ensaios de resistência à compressão e resistência à tração. Para o módulo de resiliência, foram moldados corpos-de-prova de 6,5 x 10 cm e para o módulo complexo foram moldados corpos-de-prova de 10 x 15 cm, todos com 28 dias de cura. A análise dos resultados mostrou que ambas as resistências e módulos estudados aumentam linearmente com o aumento da quantidade de cimento e exponencialmente com a redução da porosidade. Os resultados também mostraram que o material apresenta características viscoelásticas oriundas do material fresado. A relação porosidade/teor volumétrico de cimento ajustado por um coeficiente [η/(Civ)0,41] mostrou-se adequada na previsão das resistências e módulos para todas as misturas estudadas. O desempenho satisfatório colabora com a possibilidade de abranger os estudos destes materiais.The Brazilian highways are fundamental to the productive chain once promote the integration of regions, states, ports, railways, waterways and airports. The quality of the surface is a major determinant of the performance of travelers during their travels. One way to correct the defects in the pavements is the restoration currently being used through milling of the asphalt coating and its reuse. In the operation of a drilling asphalt coating, such activity produces a lot of waste in highway restoration works, called Reclaimed Asphalt Pavement (RAP), which is composed of aggregates (coarse and fine) and asphalt binder. The use of such material is the main objective of present research, targeting the grain size and chemical stabilization, the latter adding Portland cement. This research aims to evaluate, through laboratory testing, the viability of using a mixture of RAP and powdered rock chemically stabilized with Portland cement for layers in flexible pavements, correlating the porosity/cement ratio (η/Civ) with stiffness and resistance parameters of the mixtures. The RAP used in present research comes from restoration of the BR-290. The grain size stabilization was performed; RAP content being determined as 70% and 30% of powdered rock. The chemical stabilization was carried out with early strength Portland cement contents of 3%, 5% e 7%. Specimens’10x20 cm were manufactured for the unconfined compressive and splitting tensile tests. For the resilient modulus, specimens had 6.5x10cm and for the dynamic modulus specimens had10x15 cm. All ests were cured for 28 days. The results showed that both, resistance and modules increase linearly with increasing amount of cement and exponentially with decreasing of the porosity. The results also show that the material has viscoelastic characteristics originating from the RAP. The relationship between the porosity/cement ratio adjusted by a coefficient [η/(Civ)0.41] proved adequate in predicting resistance and modules for all studied mixtures. Satisfactory performance corroborates the possibility of covering of the studies of this material.
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Pires, Gustavo Menegusso. "ESTUDO DA ESTABILIZAÇÃO GRANULOMÉTRICA E QUÍMICA DE MATERIAL FRESADO COM ADIÇÃO DE CIMENTO PORTLAND E CINZA DE CASCA DE ARROZ PARA APLICAÇÃO EM CAMADAS DE PAVIMENTOS." Universidade Federal de Santa Maria, 2014. http://repositorio.ufsm.br/handle/1/7865.
Abstract:
Coordenação de Aperfeiçoamento de Pessoal de Nível SuperiorRoad transport is of great importance for many countries, in Brazil it can be even more extreme, due to the concentration of cargo through this modal. We also know that maintenance costs are elevated, forcing managers and researchers to find new alternatives to increase the utilization of materials, reduce energy consumption, speed up restoration interventions, among others. Besides the high costs, another important factor that stands out is the environmental issue, which is directly affected in the construction and maintenance of highways, whether using natural materials, movements of soils, in the fuel used by the equipment, etc. Thus, it becomes feasible to study reuse of old materials in the execution of highways recycling of deteriorated pavement, because all the material can be used for construction of a new layer, and with little addition of new materials for stabilization, reducing the consumption. Therefore, the material deteriorated asphalt pavement, the Reclaimed Asphalt Pavement (RAP), is the objective of this research, aiming to stabilize pavement layers in two ways, the particle size and chemical stabilization, the latter with the addition of Portland cement and rice husk ash. This research aims to evaluate, through laboratory testing, the feasibility of using pure and stabilized milled material (mechanical, chemical and particle size) in layers of flexible pavements. The milled materials are from BR-290 and ERS-509. Particle size stabilization was performed and determined the level of 70% of milled material and 30% of natural aggregate. For testing of compressive strength were molded into test specimens of 10x20 cm with different levels of Portland cement (CP IV-32), and determine the content of 4,86% (BR-290) and 5,37% (ERS-569) from the compressive strength of 2.1 MPa at 28 days. From the results obtained, specimens were molded for testing the Axial compressive strength, tensile strength by diametrical compression and resilient modulus; in these specimens, the cement was replaced by Rice Husk Ash (mesh #325 and #500) in ratios of 15, 30 and 50% by weight of cement content, and put into moist chamber for 7, 28 and 160 curing days. The results showed that the amount of 15% of CCA reached values very close to the reference mixtures. The satisfactory performance confirms the possibility to cover studies of these materials.
O transporte rodoviário é de grande importância para muitos países, no Brasil isso pode ser ainda mais extremo devido à concentração da movimentação das cargas através deste modal. Sabemos também que os custos de manutenção são elevados, forçando os gestores e pesquisadores a encontrar sempre novas alternativas para melhorar o aproveitamento dos materiais, diminuir o consumo de energia, agilizar as intervenções de restauração, entre outros. Outro fator importante que se destaca é a questão ambiental, onde é diretamente afetada nas construções e manutenções de rodovias, seja no consumo de materiais naturais, nas movimentações de terras, nos combustíveis utilizados, etc. Assim, torna-se viável o estudo de reaproveitamento dos materiais antigos das rodovias, na execução da reciclagem do pavimento deteriorado, pois todo o material poderá ser utilizado para construção de uma nova camada. Portanto, o material asfáltico do pavimento deteriorado, o fresado, é o objetivo de estudo desta pesquisa, visando a estabilização granulométrica e química, esta última com adição de cimento Portland e cinza de casca de arroz. Esta pesquisa objetivou avaliar, através de ensaios laboratoriais, a viabilidade da utilização de material fresado puro e estabilizado (mecânica, granulométrica e quimicamente) em camadas de pavimentos flexíveis. Os materiais fresados são oriundos da BR-290 e da ERS-509. Foi realizada estabilização granulométrica, sendo determinado o teor de 70% de material fresado e 30% de agregado natural. Para ensaio de resistência à compressão simples foram moldados em corpos-de-prova de 10x20 cm com diferentes teores de cimento Portland (CP-IV 32), sendo determinados os teores de 4,86% (BR-290) e 5,37% (ERS-569) a partir da resistência à compressão de 2,1 MPa aos 28 dias. A partir dos resultados obtidos foram moldados corpos de prova para ensaios de resistência à compressão, resistência à tração e módulo de resiliência; sendo nestes substituído em massa o CP-IV 32 em 15, 30 e 50% por cinza de casca de arroz moída (CCA #325 e CCA #500), colocados em câmara úmida por 7, 28 e 160 dias. A análise dos resultados mostrou que o teor de 15% de CCA alcançou valores muito próximos das misturas de referência. O desempenho satisfatório corrobora com a possibilidade de abranger os estudos destes materiais.
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Roper, Matthew B. "Evaluation of Laboratory Durability Tests for Stabilized Aggregate Base Materials." BYU ScholarsArchive, 2007. https://scholarsarchive.byu.edu/etd/902.
Abstract:
The Portland Cement Association commissioned a research project at Brigham Young University to compare selected laboratory durability tests available for assessing stabilized aggregate base materials. The laboratory research associated with this project involved two granular base materials, three stabilizers at three concentration levels each, and three durability tests in a full-factorial experimental design. The granular base materials consisted of an aggregate-reclaimed asphalt pavement blend obtained from Interstate 84 (I-84) and a crushed limestone obtained from U.S. Highway 91 (US-91), while the three stabilizer types included Class C fly ash, lime-fly ash, and Type I/II Portland cement. Specimens were tested for durability using the freeze-thaw test, the vacuum saturation test, and the tube suction test. Analyses of the test results indicated that the unconfined compressive strength (UCS) and retained UCS were higher for specimens tested in freeze-thaw cycling than the corresponding values associated with vacuum saturation testing. This observation suggests that the vacuum saturation test is more severe than the freeze-thaw test for materials similar to those evaluated in this research. The analyses also indicated that the I-84 material retained more strength during freeze-thaw cycling and vacuum saturation and exhibited lower final dielectric values during tube suction testing than the US-91 material. Although the I-84 material performed better than the US-91 material, the I-84 material required higher stabilizer concentrations to reach the target 7-day UCS values specified in this research. After freeze-thaw testing, the Class C fly-treated specimens were significantly stronger than both lime-fly ash- and cement-treated specimens. In the vacuum saturation test, none of the three stabilizer types were significantly different from each other with respect to either UCS or retained UCS. Dielectric values measured during tube suction testing were lowest for cement-treated specimens, indicating that cement performed better than other stabilizers in reducing the moisture/frost susceptibility of the treated materials. The results also show that, as the stabilizer concentration level increased from low to high, specimens performed better in nearly all cases. A strong correlation was identified between UCS after the freeze-thaw test and UCS after the vacuum saturation test, while very weak correlations were observed between the final dielectric value after tube suction testing and all other response variables. Differences in variability between test results were determined to be statistically insignificant. Engineers interested in specifying a comparatively severe laboratory durability test should consider vacuum saturation testing for specimens treated with stabilizers similar to those evaluated in this research. The vacuum saturation test is superior to both the freeze-thaw and tube suction tests because of the shorter duration and lack of a need for daily specimen monitoring. Although the Class C fly ash used in this research performed well, further investigation of various sources of Class C fly ash is recommended because of the variability inherent in that material. Similar research should be performed on subgrade soils, which are also routinely stabilized in pavement construction. Research related to long-term field performance of stabilized materials should be conducted to develop appropriate thresholds for laboratory UCS values in conjunction with vacuum saturation testing.
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Al, khasawneh Mohammad. "Evaluation of Novel Construction Technologies and Materials for Roadway Unpaved Shoulders." University of Cincinnati / OhioLINK, 2020. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1595848023340553.
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MAZZONI, GIORGIA. "Self-healing potential and RAP inclusion as sustainable strategies for never-ending bituminous materials." Doctoral thesis, Università Politecnica delle Marche, 2018. http://hdl.handle.net/11566/252978.
Abstract:
Benefici economico-ambientali incoraggiano l’uso di fresato (RAP), proveniente dalla demolizione di vecchie pavimentazioni stradali, da introdurre nella produzione di nuove miscele. In particolare, riciclare a caldo il RAP permette una riduzione dei costi di produzione e dei problemi di smaltimento, oltre a un risparmio delle risorse naturali, grazie allo sfruttamento della fase sia bituminosa sia litica. Tuttavia, i regolamenti delle agenzie stradali e pubbliche amministrazioni impongono restrizioni sulle percentuali di RAP implementabili (10÷30%) per la scarsa conoscenza dei meccanismi di interazione tra bitume riattivato da RAP e bitume vergine. Assunzioni inaccurate possono causare ammaloramenti prematuri della miscela, come fessurazioni da fatica, data la più severa ossidazione, e conseguente rigidezza, del bitume da RAP rispetto a quello vergine.
In questo contesto, l’attività di dottorato si è posta l’obiettivo di valutare gli effetti causati dal riciclaggio a caldo di alti quantitativi di RAP. Poiché la prestazione in sito di miscele bituminose è strettamente legata alla fase legante e ai suoi costituenti (filler e bitume), la sperimentazione è stata indirizzata all’analisi delle interazioni tra diverse tipologie e dosaggi di bitumi da RAP, rigeneranti e filler. Accanto alla “classica” caratterizzazione reologica, protocolli di prova innovativi sono stati applicati per ottenere un quadro globale del comportamento dei materiali e comprensivo di risposta a fatica, self-healing e tixotropia.
Sulla base delle evidenze sperimentali, l’impiego di un maggior contenuto di RAP è possibile, senza l’insorgenza di effetti dannosi sulla miscela finale, con una corretta progettazione. La tecnica di produzione, stesa e compattazione, la provenienza e le proprietà del RAP e dell’eventuale rigenerante devono essere selezionate opportunamente per migliorare le proprietà della miscela alle basse e intermedie temperature senza comprometterne le prestazioni alle alte temperature.Economic and environmental advantages encourage the use of Reclaimed Asphalt Pavement (RAP), coming from the milling of old pavements, to be introduced in new bituminous mixture. In particular, hot recycling of RAP allows a reduction of production costs and disposal issues as well as natural resources conservation thanks to the exploitation of both bituminous and lytic component. However, regulations of road agencies and public administrations usually impose restrictions on RAP percentages (from 10 to 30%) due to uncertainties concerning the interaction between bitumen released from RAP and virgin bitumen. Inaccurate assumptions on the related effects could lead to mixtures subjected to premature distresses, such as fatigue failure, considering the higher oxidation, and consequently viscosity (stiffness), of aged bitumens if compared to that of virgin bitumens. In this context, the Ph.D research aimed at evaluating the effects caused by hot recycling of high RAP contents. Since it is expected that field performance of bituminous mixtures is mainly led by mastic phase and its components (i.e. filler and bitumen), the experimental study focused on analysing interactions among different types and dosages of RAP bitumens, rejuvenators and fillers. Besides the “classical” rheological characterisation, more innovative tests and analyses were performed in order to get an overall picture of the mechanical behaviour of the materials investigated in terms of fatigue, self-healing and thixotropy. Based on the overall findings, the inclusion of higher RAP contents appears possible, without negatively affecting the final mixture performance, when an appropriate design is considered. Production process, paving technology, source, properties and dosage of RAP and, eventually, rejuvenator need to be properly selected so as to improve low and intermediate temperature properties of the mixture without penalising its high temperature performance.
11
Nguyen, Viet Hung. "Effects of laboratory mixing methods and RAP materials on performance of hot recycled asphalt mixtures." Thesis, University of Nottingham, 2009. http://eprints.nottingham.ac.uk/10863/.
Abstract:
The primary work reported in this thesis is concerned mainly with the effects of different mixing methods and RAP materials on homogeneity and mechanical properties of hot recycled asphalt mixtures. The recycled asphalt mixture conforms to the requirement of BS 4987-1 (2005) for dense bitumen macadam size 10 mm (DBM 10 mm). The proportion of RAP in the recycled mixture is 40%. RAP materials are artificially aged and processed in the laboratory to prevent the variability of RAP gradation, bitumen content, and the origin. Laboratory RAP is also used to assure that every single RAP particle is an agglomerate of RAP aggregate and binder. The mixing procedures include Black Rock (BR), Complete Blending (CB), the SHRP procedure, and a newly developed field simulation method (FS). The primary difference between these methods is the mixing mechanism. The BR case implies the situation in which there is completely no interaction between RAP and virgin binder. On the contrary, RAP and virgin binder are fully interacted in the CB case. The mixing procedures for BR and CB cases conform to those for conventional asphalt mixtures. However, the bitumen for BR case is pure virgin bitumen. In addition, the bitumen for CB is the blend between RAP and virgin binder. The RAP/virgin binder proportion is 4/6. In the SHRP method, RAP is preheated at 110oC for two hours before being mixed with virgin aggregate and binder for 2 minutes at 130oC. In the FS method on the contrary, the mixing procedure duplicates what occurs in the asphalt mixing plant. RAP is mixed with superheated virgin aggregate (215oC) for different durations before this combination is blended with virgin bitumen for 2 minutes at 130oC. The RAP/superheated virgin aggregate mixing duration starts from short mixing time where RAP still exists at approximately original size and gradually increases until the change in RAP lump size is insignificant. Depending on the size of RAP used, RAP/superheated virgin aggregate mixing duration varies from 1 to 8 minutes. The homogeneity of hot recycled asphalt mixture is examined by using virgin binder with a different colour from that of RAP binder. The colour of virgin binder is obtained by mixing clear binder (Shell Mexphalt C 160/220 Pen) with iron oxide pigment. The proportion of pigment is 10% by weight of the binder making this binder red. The use of virgin binder with different colour from that of RAP binder helps to clearly differentiate the locations of RAP and virgin materials. Surfaces of slices cut from compacted recycled specimens are photographed by digital camera. The analysis of these surfaces in vertical order allows the locations of RAP material to be qualitatively identified in a 3D manner. Stiffness modulus values of samples for homogeneity assessment are also determined by indirect tensile stiffness test. The stiffness test is carried out in four directions along the circumference of each specimen with 45o angular increments. The experimental results show that the stiffness measurement in four directions can indicate the heterogeneity of recycled mixture. The variation in stiffness values in different measured directions will be substantial for heterogeneous mixtures and minor in the case where recycled mixtures are homogeneous. The results indicate there are mutual relations between mixing effort, homogeneity, and stiffness values of recycled asphalt mixtures. The longer mixing time will enhance the homogeneity and reduce the variation in stiffness values of recycled mixture. In addition, as more RAP and virgin binder are incorporated, the stiffness values of recycled mixture generally increase once the mixing time is extended. As the clear binder is dyed red by 10% by weight of iron oxide, the proportion of the pigment certainly alters the flow characteristic of binder. This might affect the mixing process and rejuvenating effect between virgin and aged binder. Therefore, the effects of mixing methods and RAP sizes on mechanical performance of hot recycled asphalt mixtures are further investigated using normal straight run bitumen 160/220 Pen as virgin binder. The assessment indicators include stiffness modulus, resistance to fatigue damage, and resistance to permanent deformation. The experimental results indicate that the conventional laboratory mixing method (SHRP) tends to overestimate the mechanical properties of recycled asphalt mixture. The long RAP preheating time that never exists in the industry coincidentally enhances the reaction between RAP and virgin binder. The long RAP preheating time also slightly alters the properties of RAP binder. For the FS method, the increase in mixing duration significantly improves the homogeneity level of recycled mixtures. The homogeneity level is also substantially affected by the size of RAP material. For the same mixing effort, the mixtures comprised of small RAP are generally more homogeneous than those made from larger RAP. The more homogeneous the mixture, the more interaction between RAP and virgin binder. Therefore, recycled mixtures become stiffer and have better resistance to permanent deformation and fatigue failure. A slightly linear increase in stiffness can result in an exponential increase in fatigue life of the recycled mixture. The mechanical properties including stiffness modulus, resistance to fatigue damage, and resistance to permanent deformation of hot recycled asphalt mixtures are not similar to those of the BR or CB mixtures, even at the favourable condition where RAP is preheated for 2 hours at 110oC in the SHRP method and 8 minutes mixing duration in the FS method. This implies that RAP does not act as Black Rock. In addition, the assumption that RAP and virgin binder are fully blended also never exists in the recycled asphalt production process.
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Veeraragavan, Ram kumar. "An Investigation of the Performance of Hot Mix Asphalt (HMA) Binder Course Materials with High Percentage of Reclaimed Asphalt Pavement (RAP) and Rejuvenators." Digital WPI, 2016. https://digitalcommons.wpi.edu/etd-theses/456.
Abstract:
Use of high percentage of Reclaimed Asphalt Pavement (RAP) material in Hot Mix Asphalt is one of the several sustainable construction alternatives being considered by many Departments of Transportation (DOT). Use of RAP in HMA helps in reducing the consumption of virgin aggregates and binder and construction cost and conserving energy. Although most of the US state agencies allow the use of 30% or more RAP in the design of Hot Mix Asphalt (HMA), the current average RAP usage is only about 10 to 20%. This is because of the uncertainty about the performance of HMA mixes with a high RAP content. Several factors influence the performance of the HMA mixes with a high RAP content. Recent research has shown that the use of a high RAP content in HMA with rejuvenators is successful in reducing the stiffness of the RAP mixes, and thereby improving their performance. The present work is carried out to explore the feasibility of using a high RAP content of 50% in a binder layer HMA with the addition of rejuvenators. Ultrasonic Pulse Velocity (UPV) test was carried out to compare the stiffness of the RAP mixes with and without the addition of rejuvenators. Moisture Induced Stress Test (MIST) was conducted to study the effect of moisture damage on the HMA mixes with high RAP content. The Indirect Tensile Strength Test (ITS) was used to determine the strength of the HMA mixes with high RAP content. In addition, creep compliance and Semicircular Bend (SCB) tests were carried out to determine the cracking potential and fracture strength of the mixes respectively. The addition of rejuvenators was found to significantly reduce the stiffness of the mix with high RAP content. The predicted complex shear modulus (G*) obtained from the Hirsch model and performance grading tests on extracted binders confirmed the effectiveness of the addition of rejuvenators in reducing the stiffness of recycled asphalt binder in the recycled mixes.
13
Stimilli, Arianna. "Advanced Experimental Study on Rheological and Mechanical Properties of Hot Recycled Bituminous Materials with High RAP Content." Doctoral thesis, Università Politecnica delle Marche, 2015. http://hdl.handle.net/11566/242917.
Abstract:
Oggigiorno, la produzione di conglomerati con elevate percentuali di fresato (RAP) rappresenta una delle maggiori sfide da affrontare. L’inclusione di RAP garantisce vantaggi in termini ambientali ed economici, soprattutto tramite riciclaggio a caldo, tecnica che permette il simultaneo sfruttamento della fase bituminosa e lapidea di una miscela. Attualmente i quantitativi di RAP comunemente utilizzati sono limitati data la mancanza di esperienza e di prove scientifiche che dimostrino la possibilità di includere fresato senza penalizzare le prestazioni della pavimentazione.
L’attività di dottorato si è posta l’obiettivo di investigare in modo rigoroso vantaggi e svantaggi di miscele riciclate a caldo con elevate percentuali di RAP. A tal fine, è stato realizzato un vasto programma sperimentale comprendente avanzate analisi chimiche, reologiche e meccaniche su un’ampia gamma di materiali (bitumi, miscele di laboratorio e miscele realizzate in impianto). Oltre alle comuni indagini di laboratorio, sono stati elaborati innovativi protocolli di prova e metodi di elaborazione per l’analisi di problematiche non ancora propriamente affrontate in ambito scientifico (i.e. auto-riparazione, adesione, ri-attivazione del bitume nel RAP, proprietà di rilassamento).
L’ottima correlazione riscontrata fra i risultati dei diversi step di laboratorio dimostra la validità scientifica delle indagine effettuate e dei nuovi protocolli e metodi di analisi proposti. Sulla base dell’intero studio sperimentale, non emergono elementi che scoraggino l’uso di alte percentuali di RAP. Al contrario, i risultati dimostrano che tramite un accurato mix design e l’adozione di specifici accorgimenti (e.g. vagliatura del RAP in più frazioni, standardizzazione del processo produttivo) l’aggiunta di fresato può significativamente migliorare le prestazioni della pavimentazione, garantendo ottime proprietà reologiche e meccaniche.Recycling is a major challenge to address in road materials design. The inclusion in new asphalt mixtures of high amounts of Reclaimed Asphalt Pavement (RAP), coming from the milling of old pavements, provides economic and environmental benefits, particularly when referred to hot recycling since this technique allows the concurrent exploitation of bituminous and aggregate components of asphalt mixtures. Currently, the maximum amount of RAP commonly used is limited due to lack of experience and scientific proofs of the possibility to include RAP without penalizing pavement performance. The PhD research aimed at scientifically verifying advantages and disadvantages of hot recycled mixtures containing high RAP content. To this aim, a wide experimental program was carried out involving advanced chemical, rheological and mechanical analysis on a wide set of bitumens, laboratory and in plant asphalt mixtures. The latter were used to realize three full scale experimental sections along an in-service Italian highway. Besides the traditional laboratory investigations, innovative test protocols and data analysis were elaborated to address those issues not properly investigated yet, such as self-healing, adhesion, RAP bitumen re-activation degree, relaxation properties. Optimum correlation was found between the results collected in each laboratory step, hence demonstrating the scientific validity of the laboratory investigations performed and the reliability of the new test and analysis methods proposed. Based on the overall findings, no elements which discourage the use of high amount of RAP were identified. On the contrary, the study demonstrated that with proper mix design and specific precautions (e.g. RAP fractioning, gradation optimization, standardized production process) the adding of RAP guarantees optimum rheological and mechanical properties, and enhances mixture performance in terms of rutting, fatigue and thermal cracking, main distresses of a flexible pavement.
14
Shannon, Cory Patrick. "Fractionation of recycled asphalt pavement materials: improvement of volumetric mix design driteria for High-RAP content surface mixtures." Thesis, University of Iowa, 2012. https://ir.uiowa.edu/etd/3380.
Abstract:
The objective of this research is to examine the effects that different methods of RAP stockpile fractionation have on the volumetric mix design properties for high-RAP content surface mixes, with the goal of meeting all specified criteria for standard HMA mix designs. The processing of RAP materials results in the degradation of the aggregate structure of the original pavement. The increased presence of fine RAP materials in the stockpile can be attributed to the amount of crushing done on the RAP millings. Fractionation methods were designed to separate the stockpile at certain sizes to isolate the fine RAP materials which contained higher amounts of fine aggregate and negatively impacted the volumetric properties of the mix design. These isolated RAP materials were used in reduced proportions or completely eliminated, thereby decreasing the amount of fine aggregate material introduced to the mix. Mix designs were created using RAP materials included from each original stockpile and the two fractionated stockpiles created from each original stockpile at high-RAP contents of 30%, 40% and 50% by virgin binder replacement. Fractionation of RAP materials was effective in improving the volumetric properties of high-RAP content mixtures through reduction of fine aggregate material introduced by the RAP materials.
15
Vu, Quoc Hung. "Modelling pollutants leaching from recycled construction materials." Thesis, Queensland University of Technology, 2019. https://eprints.qut.edu.au/130795/1/Quoc%20Hung_Vu_Thesis.pdf.
Abstract:
This research developed new models to replicate metal leaching characteristics from recycled concrete aggregate (RCA) and reclaimed asphalt pavement (RAP). Model development was supported by a comprehensive experimental and analytical program with multiple influential factors. New models were developed so that they are readily applicable in commercial models to replicate pollutant leaching and solute transport in soil environments. Outcomes of this study will enhance the sustainable use of waste products such as RCA and RAP in the construction industry and relieve the stresses on natural quarry products.
16
Vorreyer-Hedges, Anita L. "Rape Risk Reduction Materials: How Do University Students of Color Perceive the Cultural Relevancy of These Materials?" UNF Digital Commons, 2002. http://digitalcommons.unf.edu/etd/325.
Abstract:
Few studies have investigated how race and ethnicity influence people's beliefs about rape, or what impact these beliefs have on what and how we teach college students in efforts to raise awareness about rape. The purpose of this study was to gain understanding of how students of color perceive the cultural relevance of materials commonly used on campuses for rape risk reduction education. Participants were African American and Hispanic students at a mid-sized state university. Focus group sessions and interviews were conducted with 23 student participants. Students reported that they found the rape risk reduction materials culturally relevant; however, other revisions of the materials were necessary if the materials were to connect with students. Data analysis, based on the construction of grounded theory and the use of educational criticism, revealed three recurring themes-the influence of popular culture on student perceptions of social situations, the role of racial and ethnic identity development within a global context, and developmental influences on students' ways of constructing knowledge. Therefore, rape risk reduction efforts must be culturally sensitive and developmentally appropriate, and take into consideration the influence of popular culture in order to connect with students.
17
Gomes, Neto David de Paiva. "Contribuição para as metodologias de identificação e previsão da reação álcali-agregado (RAA) utilizando agregados graníticos e a técnica de microondas." Pós-Graduação em Ciência e Engenharia de Materiais, 2014. https://ri.ufs.br/handle/riufs/3492.
Abstract:
The alkali-aggregate reaction (AAR) is a pathological manifestation that occurs in concrete structures and has concerned engineers and users of construction for decades, throughout the world. Basically, it is a chemical reaction resulting from the interaction between alkalis released from cement and some silicates in the reactive aggregates. Aggregates have been studied and there are many disagreements as to the involvement of the granitic aggregates in the AAR. This study was originated from the absence of findings on the influence of compositional and microstructural characteristics of granite aggregates in the occurrence of AAR and the inadequacy of standardized testing methods for the prediction of reaction. This research presents contributions to the methods for prediction of the AAR using microwave treatment to accelerate the formation of reaction products. For this purpose, three granitic aggregates from Sergipe were used as reference for validation of the applicability of the technique. The selected
experimental conditions have allowed rapid access to reactive mineral phases and formation of the reaction products. The results have showed that differences in reactive behavior of granitic aggregates are correlated to morphological aspects of quartz, as the presence of quartz subgrains and deformed quartz grains.A reação álcali-agregado (RAA) é uma manifestação patológica que ocorre em estruturas de concreto e tem preocupado engenheiros e usuários da construção civil há décadas. Basicamente, é uma reação química decorrente da interação entre os álcalis do cimento e alguns silicatos dos agregados considerados reativos. Agregados do mundo inteiro têm sido estudados e muitas divergências existem quanto à participação dos agregados graníticos na RAA. Este estudo partiu da necessidade de conclusões sobre a influência das características composicionais e microestruturais dos agregados graníticos na ocorrência da RAA e da inadequação dos métodos de ensaios normatizados para a previsão da reação. Diante deste cenário, esta pesquisa apresenta contribuições para a previsão da RAA utilizando o tratamento com microondas para acelerar a formação dos produtos de reação. Para isso, três agregados graníticos do Estado de Sergipe foram usados como referência para a validação da aplicabilidade da técnica. As condições experimentais selecionadas permitiram o rápido acesso às fases minerais responsáveis pela reatividade e a formação de produtos da RAA. Os resultados mostraram que as diferenças no comportamento reacional dos agregados graníticos estão correlacionadas a aspectos morfológicos do quartzo, como a presença de subgrãos de quartzo e de grãos de quartzos deformados.
18
Samuels, Benjamin R. (Benjamin Richard). "Tape automated bonding--product and process ramp-up." Thesis, Massachusetts Institute of Technology, 1990. http://hdl.handle.net/1721.1/14124.
Abstract:
Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Materials Science and Engineering, 1990, and Thesis (M.S.)--Massachusetts Institute of Technology, Sloan School of Management, 1990.Includes bibliographical references.
by Benjamin R. Samuels.
M.S.
19
MELIS, GIANLUCA. "Life cycle assessment to support the design of a new road manufacturing process with recycled materials." Doctoral thesis, Politecnico di Torino, 2022. https://hdl.handle.net/11583/2973987.
20
Conti, Vito. "Studio sperimentale di miscele bituminose prodotte a freddo con il 100% di materiale di riciclo per ripristino di pavimentazioni stradali in ambito urbano." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2022.
Abstract:
Il seguente studio propone una soluzione alternativa all'utilizzo di tecnologie tradizionali per il ripristino delle pavimentazioni in ambito urbano, a seguito di interventi di manutenzione dei sottoservizi in genere. L'obiettivo principale è trovare una soluzione alternativa che sia più sostenibile da un punto di vista economico, energetico e soprattutto ambientale. L'idea prevede il confezionamento di miscele bituminose prodotte con 100% materiale proveniente da scarifica o fresatura con l'impiego della tecnologia a freddo, in particolare utilizzando un additivo chimico. Sono state analizzate le differenze di caratteristiche di tre miscele bituminose confezionate con tre tipologie di granulato bituminoso mantenendo però costante la percentuale di additivo chimico e di cemento. Le operazioni di caratterizzazione sia relative ai materiali che ai provini sono state eseguite rispettando quanto previsto dalle normative europee. Dapprima sono state analizzate le caratteristiche fisiche e meccaniche dei materiali oggetti di studio, in termini di distribuzione granulometrica, contenuto di legante solubile, quantità di materiale estraneo, indice di forma, indice di appiattimento e resistenza alla frammentazione. Dopodiché si è proceduto con lo studio del dosaggio ottimale della miscela e la compattazione dei provini per mezzo della Pressa a Taglio Giratoria e Compattatore Marshall. Infine, attraverso l'esecuzione delle varie prove, sono state determinate le caratteristiche prestazionali dei provini così confezionati, in termini di contenuto dei vuoti, addensabilità, resistenza a trazione indiretta, modulo di rigidezza, sensibilità all'acqua, resistenza alla frammentazione e all'urto e resistenza allo slittamento/derapaggio. Dai risultati ottenuti si evidenziano limitate prestazioni per i conglomerati testati, probabilmente a causa di una non adeguata distribuzione granulometrica.
21
Šperka, Pavel. "Vliv použití R - materiálu na funkční vlastnosti asfaltových směsí." Master's thesis, Vysoké učení technické v Brně. Fakulta stavební, 2015. http://www.nusl.cz/ntk/nusl-227637.
Abstract:
Diploma thesis deals with the topic of using recycled material in the production of asphalt mixtures. In the theoretical part the methods of recycling flexible pavement are described and as well as ways in which recycled material is added to asphalt mixtures produced by the stationary hot mix plant. The thesis also deals with the current state of recycled material use in the Czech Republic and the reasons for its possible greater use. The practical part of the thesis studies the effect of using the amount of 20% recycled material to asphalt mixtures of asphalt concrete for wearing course ACO11+, on selected functional properties of these mixtures. It is also investigates the influence of bitumen binder contained in the recycled material, on the final properties in manufactured asphalt mixtures. An integral part of this thesis is a description of all methods that were used during the processing of the practical part. In the end of this thesis there are some results of findings about adding recycled material into asphalt mixtures.
22
Keith, Christopher Kenneth. "Accelerating time-to-money for a semiconductor wafer fab capacity ramp." Thesis, Massachusetts Institute of Technology, 1996. http://hdl.handle.net/1721.1/29112.
Abstract:
Thesis (M.S.)--Massachusetts Institute of Technology, Sloan School of Management, 1996, and Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Materials Science & Engineering, 1996.Includes bibliographical references (leaf 83
by Christopher K. Keith.
M.S.
23
Bilir, Levent İlken Zafer. "Estimation of the total solidification time of a liquid phase change material enclosed in cylindrical and spherical containers/." [s.l.]: [s.n.], 2003. http://library.iyte.edu.tr/tezler/master/makinamuh/T000248.rar.
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Pessoa, R?gia Chacon. "Estudo das caracter?sticas magn?ticas e absorvedoras das ferritas de nizn, niznmn, mnzn, nimg, nicuzn e nicuznmg obtidas via m?todo do citrato precursor." Universidade Federal do Rio Grande do Norte, 2009. http://repositorio.ufrn.br:8080/jspui/handle/123456789/17716.
Abstract:
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Were synthesized systems Ni0,5Zn0,5Fe2O4, i0,2Zn0,5Mn0,3Fe2O4, Mn0,5Zn0,5Fe2O4, Ni0,5Mg0,5Fe2O4, Ni0,2Cu0,3Zn0,5Fe2O4 and Ni0,2Cu0,3Zn0,5Mg0,08Fe2O4, the precursors citrate method. The decomposition of the precursors was studied by thermogravimetric analysis and spectroscopy in the infrared region, the temperature of 350?C/3h. The evolution of the phases formed after calcinations at 350, 500, 900 and 1100?C/3h was accompanied by X-ray diffraction using the Rietveld refinement to better identify the structures formed. The materials were also analyzed by scanning electron microscopy, magnetic measurements and analysis of the reflectivity of the material. The samples calcined at different temperatures showed an increase of crystallinity with increasing calcination temperature, verifying that for some compositions at temperatures above 500?C precipitates of second phase such as hematite and CuO. The compositions of manganese present in the structure diffusion processes slower due to the ionic radius of manganese is greater than for other ions substitutes, a fact that delays the stabilization of spinel structure and promotes the precipitation of second phase. The compositions presented with copper precipitation CuO phase at a temperature of 900 and 1100?C/3h This occurs according to the literature because the concentration of copper in the structure is greater than 0.25 mol%. The magnetic measurements revealed features of a soft ferrimagnetic material, resulting in better magnetic properties for the NiZn ferrite and NiCuZnMg at high temperatures. The reflectivity measurements showed greater absorption of electromagnetic radiation in the microwave band for the samples calcined at 1100?C/3h, which has higher crystallite size and consequently the formation of multi-domain, increasing the magnetization of the material. The results of absorption agreed with the magnetic measurements, indicating among the ferrites studied, those of NiZn and NiCuZnMg as better absorbing the incident radiation.
Foram sintetizados os sistemas Ni0,5Zn0,5Fe2O4, Ni0,2Zn0,5Mn0,3Fe2O4, Mn0,5Zn0,5Fe2O4, Ni0,5Mg0,5Fe2O4, Ni0,2Cu0,3Zn0,5Fe2O4 e Ni0,2Cu0,3Zn0,5Mg0,08Fe2O4, pelo m?todo dos citratos precursores. A decomposi??o dos precursores foi estudada por an?lise termogravim?trica e espectroscopia na regi?o do infravermelho, na temperatura de 350?C/3h. A evolu??o das fases formadas ap?s as calcina??es a 350, 500, 900 e 1100?C/3h foi acompanhada por difra??o de raios X utilizando o refinamento de Rietveld, para melhor identifica??o das estruturas formadas. Os materiais foram tamb?m analisados por microscopia eletr?nica de varredura, medidas magn?ticas e an?lise da refletividade do material. As amostras calcinadas em diferentes temperaturas indicaram um aumento da cristalinidade com o aumento da temperatura de calcina??o, verificando-se que, para algumas composi??es, em temperaturas acima de 500?C ocorre a precipita??o de segunda fase, como hematita e CuO. As composi??es com mangan?s na estrutura apresentaram processos de difus?o mais lentos devido ao raio i?nico do mangan?s ser maior em rela??o aos outros ?ons substituintes, fato que retarda a estabiliza??o da estrutura espin?lio e favorece a precipita??o de segunda fase. As composi??es com cobre apresentaram precipita??o da fase CuO na temperatura de 900 e 1100?C/3h, fato que ocorre segundo a literatura porque a concentra??o de cobre na estrutura ? maior que 0,25 mol%. As medidas magn?ticas revelaram racter?sticas de um material ferrimagn?tico macio, obtendo-se melhores ar?metros magn?ticos para as ferritas de NiZn e NiCuZnMg em altas temperaturas. As medidas de refletividade mostraram maior absor??o da radia??o eletromagn?tica na faixa de microondas para as amostras calcinadas a 1100?C/3h, que tem maior tamanho do cristalito e em conseq??ncia forma??o de multidom?nios, aumentando a magnetiza??o do material. Os resultados de absor??o concordaram com as medidas magn?ticas, indicando dentre as ferritas estudadas, as de NiZn e NiCuZnMg como melhores absorvedoras da radia??o incidente.
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Sjödén, Therese. "Sensitivity Analysis and Material Parameter Estimation using Electromagnetic Modelling." Doctoral thesis, Linnéuniversitetet, Institutionen för datavetenskap, fysik och matematik, DFM, 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:lnu:diva-18689.
Abstract:
Estimating parameters is the problem of finding their values from measurements and modelling. Parameters describe properties of a system; material, for instance, are defined by mechanical, electrical, and chemical parameters. Fisher information is an information measure, giving information about how changes in the parameter effect the estimation. The Fisher information includes the physical model of the problem and the statistical model of noise. The Cramér-Rao bound is the inverse of the Fisher information and gives the best possible variance for any unbiased estimator. This thesis considers aspects of sensitivity analysis in two applied material parameter estimation problems. Sensitivity analysis with the Fisher information and the Cramér-Rao bound is used as a tool for evaluation of measurement feasibilities, comparison of measurement set-ups, and as a quantitative measure of the trade-off between accuracy and resolution in inverse imaging. The first application is with estimation of the wood grain angle parameter in trees and logs. The grain angle is the angle between the direction of the wood fibres and the direction of growth; a large grain angle strongly correlates to twist in sawn timber. In the thesis, measurements with microwaves are argued as a fast and robust measurement technique and electromagnetic modelling is applied, exploiting the anisotropic properties of wood. Both two-dimensional and three-dimensional modelling is considered. Mathematical modelling is essential, lowering the complexity and speeding up the computations. According to a sensitivity analysis with the Cramér-Rao bound, estimation of the wood grain angle with microwaves is feasible. The second application is electrical impedance tomography, where the conductivity of an object is estimated from surface measurements. Electrical impedance tomography has applications in, for example, medical imaging, geological surveillance, and wood evaluation. Different configurations and noise models are evaluated with sensitivity analysis for a two-dimensional electrical impedance tomography problem. The relation between the accuracy and resolution is also analysed using the Fisher information. To conclude, sensitivity analysis is employed in this thesis, as a method to enhance material parameter estimation. The sensitivity analysis methods are general and applicable also on other parameter estimation problems.Estimering av parametrar är att finna deras värde utifrån mätningar och modellering. Parametrar beskriver egenskaper hos system och till exempel material kan definieras med mekaniska, elektriska och kemiska parametrar. Fisherinformation är ett informationsmått som ger information om hur ändringar i en parameter påverkar estimeringen. Fisherinformationen ges av en fysikalisk modell av problemet och en statistisk modell av mätbruset. Cramér-Rao-gränsen är inversen av Fisherinformationen och ger den bästa möjliga variansen för alla väntevärdesriktiga estimatorer.Den här avhandlingen behandlar aspekter av känslighetsanalys i två tillämpade estimeringsproblem för materialparametrar. Känslighetsanalys med Fisherinformation och Cramér-Rao-gränsen används som ett redskap för utvärdering av möjligheten att mäta och för jämförelser av mätuppställningar, samt som ett kvantitativt mått på avvägningen mellan noggrannhet och upplösning för inversa bilder. Den första tillämpningen är estimering av fibervinkeln hos träd och stockar. Fibervinkeln är vinkeln mellan växtriktningen och riktningen hos träfibern och en stor fibervinkel är relaterad till problem med formstabilitet i färdiga brädor. Mikrovågsmätningar av fibervinkeln presenteras som en snabb och robust mätteknik. I avhandlingen beskrivs två- och tredimensionella elektromagnetiska modeller som utnyttjar anisotropin hos trä. Eftersom matematisk modellering minskar komplexiteten och beräkningstiden är det en viktig del i estimeringen. Enligt känslighetsanalys med Cramér-Rao-gränsen är estimering av fibervinkeln hos trä möjlig. Den andra tillämpningen är elektrisk impedanstomografi, där ledningsförmågan hos objekt bestäms genom mätningar på ytan. Elektrisk impedanstomografi har tillämpningar inom till exempel medicinska bilder, geologisk övervakning och trämätningar. Olika mätkonfigurationer och brusmodeller utvärderas med känslighetsanalys för ett tvådimensionellt exempel på elektrisk impedanstomografi. Relationen mellan noggrannhet och upplösning analyseras med Fisher information. För att sammanfatta beskrivs känslighetsanalys som en metod för att förbättra estimeringen av materialparametrar. Metoderna för känslighetsanalys är generella och kan tillämpas också på andra estimeringsproblem för parametrar.
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Sudhendra, Chandrika. "A Novel Chip Resistor Spacecloth For Radar Absorbing Materials." Thesis, Indian Institute of Science, 2006. https://etd.iisc.ac.in/handle/2005/280.
Abstract:
Spacecloth design and development is vital and crucial in Radar Absorbing Materials (RAM) for achieving Low Observability in an Aircraft or an Unmanned Air Vehicle(UAV). The RAM design translates into the spacecloth design. The spacecloths form the constituent layers in a broadband Jaumann absorber in which case they have to be designed for various values of surface resistivity. The design specifications of spacecloth(s) in RAMS is well understood and documented in literature. But the design of spacecloth hitherto, has been the domain of materials' scientists wherein the specified properties of the spacecloth are achieved by an iterative, trial and error process, by mixing various constituents in different proportions to get the design specified surface resistivity in the final end-product. In an effort to bridge this gap, a novel spacecloth for RAM applications is proposed in the thesis. It is proposed that a repetitive geometrical grid network of chip resistors simulates spacecloth. The sheet resistivity of the spacecloth is derived by analyzing various geometries like square, rectangle, triangle and hexagonal grids. The transmission and reflection loss for the chip resistor spacecloth is derived. The design of chip resistor spacecloths for operation at S and C bands is given followed by experimental verification using waveguide simulator experiments. Numerical study of multilayer RAM has been carried out with exponential taper variation of surface resistivities for constituent spacecloth layers and design curves are given for multilayer RAM both for normal and oblique incidence for TE and TM polarizations.
27
Sudhendra, Chandrika. "A Novel Chip Resistor Spacecloth For Radar Absorbing Materials." Thesis, Indian Institute of Science, 2006. http://hdl.handle.net/2005/280.
Abstract:
Spacecloth design and development is vital and crucial in Radar Absorbing Materials (RAM) for achieving Low Observability in an Aircraft or an Unmanned Air Vehicle(UAV). The RAM design translates into the spacecloth design. The spacecloths form the constituent layers in a broadband Jaumann absorber in which case they have to be designed for various values of surface resistivity. The design specifications of spacecloth(s) in RAMS is well understood and documented in literature. But the design of spacecloth hitherto, has been the domain of materials' scientists wherein the specified properties of the spacecloth are achieved by an iterative, trial and error process, by mixing various constituents in different proportions to get the design specified surface resistivity in the final end-product. In an effort to bridge this gap, a novel spacecloth for RAM applications is proposed in the thesis. It is proposed that a repetitive geometrical grid network of chip resistors simulates spacecloth. The sheet resistivity of the spacecloth is derived by analyzing various geometries like square, rectangle, triangle and hexagonal grids. The transmission and reflection loss for the chip resistor spacecloth is derived. The design of chip resistor spacecloths for operation at S and C bands is given followed by experimental verification using waveguide simulator experiments. Numerical study of multilayer RAM has been carried out with exponential taper variation of surface resistivities for constituent spacecloth layers and design curves are given for multilayer RAM both for normal and oblique incidence for TE and TM polarizations.
28
Kim, Dhohyung. "Mechanism of Maternal Antibody Inhibition and Vaccination Strategies in the presence of Maternal Antibodies." The Ohio State University, 2012. http://rave.ohiolink.edu/etdc/view?acc_num=osu1330968863.
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Kumar, Vivek Ashok. "Design and evaluation of scaffolds for arterial grafts using extracellular matrix based materials." Diss., Georgia Institute of Technology, 2011. http://hdl.handle.net/1853/45869.
Abstract:
For small diameter (<6 mm) blood vessel replacements, lack of collaterals and vascular disease preclude homografts; while synthetic analogs, ePTFE, expanded polytetrafluoroethylene, and PET, polyethyleneterephathalate, are prone to acute thrombosis and restenosis. It is postulated that the hierarchical assembly of cell populated matrices fabricated from protein analogs provides a new design strategy for generating a structurally viable tissue engineered vascular graft. To this end, synthetic elastin and collagen fiber analogs offer a novel strategy for creating tissue engineered vascular grafts with mechanical and biological properties that match or exceed those of native vessels. This work details techniques developed for the fabrication of prosthetic vascular grafts from a series of extracellular matrix analogs composed of nanofibrous collagen matrices and elastin-mimetic proteins, with and without cells, and subsequent evaluation of their biocompatibility and mechanical properties. The work details the fabrication and mechanical analysis of vascular grafts made from aforementioned protein analogs. Subesequent studies detail seeding and proliferation of rodent mesenchymal stem cells on protein-based composites to recapitulate the media of native vasculature. Finally detailing in vivo biocompatibility and stability of tissue engineered vascular grafts.
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Brown, Ashley Vannoy. "Cement Stabilization of Aggregate Base Materials Blended with Reclaimed Asphalt Pavement." Diss., CLICK HERE for online access, 2006. http://contentdm.lib.byu.edu/ETD/image/etd1314.pdf.
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Demir, Hasan Ülkü Semra. "Synergistic effect of natural zeolites on flame retardant additives/." [s.l.]: [s.n.], 2004. http://library.iyte.edu.tr/tezler/master/kimyamuh/T000514.rar.
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Teixeira, Luísa Maria de Oliveira. "Abrigos com pinturas rupestres de Trás-os-Montes e Alto Douro (Pala Pinta, Penas Róias e Cachão da Rapa). Paisagens, signos e cultura material." Master's thesis, Faculdade de Ciências Sociais e Humanas, Universidade Nova de Lisboa, 2012. http://hdl.handle.net/10362/9293.
Abstract:
Dissertação apresentada para cumprimento dos requisitos necessários à obtenção
do grau de Mestre em ArqueologiaA presente dissertação corresponde ao estudo de três abrigos rupestres, localizados em Trás-os-Montes e Alto Douro, tendo como objecto de análise aspectos da paisagem em que estes se inserem, os signos e os testemunhos da cultura material neles encontrados. As pinturas rupestres são um dos testemunhos das actividades individuais e/ ou colectivas ali desenvolvidas, revelando aspectos da vida das comunidades que as produziram, designadamente das suas possíveis crenças religiosas. Entender algumas das relações das comunidades humanas pretéritas com estes lugares, ajuda-nos a perceber certos comportamentos perante a Natureza.
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Mikhailenko, Peter. "Valorization of by-products and products from agro-industry for the development of release and rejuvenating agents for bituminous materials." Thesis, Toulouse 3, 2015. http://www.theses.fr/2015TOU30094/document.
Abstract:
La croissance de caution vis-à-vis l'utilisation des produits pétroliers dans la construction a nécessité le besoin de développement des alternatives. Le BTP, en particulaire pour le secteur routière, a un certain nombre des piste ou les produits pétrolières ont utilisés, par exemple le liant pour les enrobés comme les agents régénérant (pour recyclage des enrobés), mais aussi le produits qui sont utilisés sur le chantier comme les anti-adhérents (ARA) et les débituminants (BR). Alors, il y a une besoin de remplacer les produits d'origines pétrolières par les alternatives bio-sourcés. Ce présent ouvre est une partie d'un projet qui va développer une nouvelle filière dédiée à la production de nouvelles formulations pour le BTP à partir de la transformation des huiles végétales et des graisses animales. Ce thèse concerne les produits développés seront destinés au l'asphalte, et alors, deux types d'applications sont particulièrement visés : (i) des agents anti-adhérents et (ii) des agents régénérants. Un débituminant sera développé aussi. Les produits anti-adhérents ont pour fonction d'empêcher le bitume d'adhérer aux engins de travaux sans effet secondaire, théoriquement, sur la matrice liante.. L'objet du travail est de caractériser l'efficacité et l'innocuité des agents anti-adhérents développés dans le cadre du projet et de développer les méthodes expérimentales visant à les évaluer. Trois essais principaux ont été développés pour caractériser la performance et innocuité des anti-adhérents vis-à-vis des essais qui ont optimisé leur implémentation et paramètres. La performance des anti-adhérents a été caractérisé par l'essai de glissance des enrobés. L'innocuité des anti-adhérents ont été caractérisés par des essais de fendage sur les enrobés et par l'essai de la dégradation de bitume. L'essai de la dégradation de bitume a servi aussi comme une mesure de la performance de débituminant. Les essais sur les anti-adhérents commerciaux d'Etats-Unis et la France a trouvé que ils ont deux modes de fonctionnement : i) lixiviation du bitume et ii) en formation d'une interface entre le les enrobés et la surface métallique. Même comme les deux modes ont été trouvé dans des certains anti-adhérents, le mode interface ont été trouvé préférable, grâce à l'option de garder les mêmes applications du produit pour plusieurs cycles de usage. Ensuite, un produit - basé sur glycérol sourcé de l'agro-industrie - a été développé. Les débituminants commerciaux ont été essayé, aves les conclusions : i) les débituminants plus effectifs ont eu les plus grande % des esters et ii) que les esters chaines courtes (C7-10) d'hautes concentrations ont été trouvé les plus efficace. L'agent régénérant est destiné à régénérer le bitume vieilli issu des agrégats d'enrobés (RAP) en lui redonnant ses propriétés originelles et en assurant leur maintien dans le temps. Le travail sur les agents régénérants se compose de la caractérisation physico-chimique du vieillissement du bitume et du bitume vieilli avec l'agent. Plus précisément, le travail se serve des techniques de spectrométrie IRTF (avec imagerie) et thermogravimétrie. Dans ce contexte, une produit bio-sourcé a été évalué comme une régénérant. Pour la spectroscopie FTIR, une moyenne de polir le mastique a été développé pour rassuré la platitude des échantillons. La régénération du bitume a été observé avec la spectrométrie ITRF, donc quelques peaks (notamment les indices IC=O and IS=O) pendant 0-42 jours de vieillissement dans l'étuve (loin-durée). Il a été trouvé qu'une période de vieillissement de 14 jours à l'étuve était à peu près équivalente au bitume vieilli par un cycle de RTFOT + PAV en termes de rhéologie et de la pénétration. Le mastic (vieilli 14 jours) a ensuite été mélangé avec un agent de bio-source (à 7,5% en poids de mastic). Il a été constaté par imagerie FTIR que l'indicateur de l'oxydation IS=O a été réduit par l'incorporation de l'agent régénérant dans le bitumeThe growing health and environmental concerns brought on by the use of petroleum based products in the asphalt construction industry have necessitated the development of alternatives. Infrastructure, especially that involving transportation has many uses for petroleum products including, as fuel, as well as in asphalt pavement construction - where petroleum products have traditionally constituted the binder for the mix as well as the rejuvenating agents (for asphalt recycling) - along with various agents used in the construction process including bitumen removers and asphalt release agents. Thus, there is a need to replace petroleum base agents with bio-sourced and biodegradable substitutes. The present work is part of a project to develop bio-sourced (recycled from agricultural waste) products for the construction industry. This work is dedicated to developing products relating to the asphalt industry. Two types of product applications were envisioned: i) an asphalt release agent (ARA) and ii) an asphalt rejuvenating agent. Additionally, a bitumen remover (BR) developed as part of the work on the ARA. ARAs prevent asphalt from adhering to tools and equipment used in asphalt production, without producing overly negative side effects with regards to the pavement. Three principal tests methods were developed and optimized for the performance and damage to asphalt of the ARAs. The asphalt slide test was developed to quantify the performance of the ARA by sliding hot asphalt mix down a plate with the ARA applied. The testing of the damage to asphalt from ARAs consisted of testing an asphalt cylinder - in contact with an ARA for seven days - in indirect-tensile strength (ITS). The bitumen degradation test consisted of submerging a bitumen sample in an agent over a certain time and weighing the bitumen that did not dissolve in the agent. This was followed by the observation of the bitumen-ARA chemical interaction by FTIR spectrometry. This test served as an assessment of ARA damage to bitumen as well as of the performance of BRs. The testing of the commercial ARAs from both the French and USA markets found that they had two primary modes of functioning: i) by softening the bitumen and ii) by forming an interface between the asphalt and the metal surface. While some agents had elements of both, it was found that interface agents are preferable, due to the ability to use a single ARA application for multiple occasions. With this completed, a water-based bio-sourced substrate ARA - based on glycerol derived from agricultural waste - was developed. The commercially available BRs were tested as well, finding that i) the most effective BRs had the highest ester concentration and ii) that highly concentrated short chained ester (C7-10) were very effective bitumen dissolvers. The goal of rejuvenating agents is to regenerate the old bitumen from recycled asphalt pavement (RAP) by restoring the original properties and ensuring the stability of these properties over time. This part consisted of the development of methods for bitumen and aging, as well as characterization of the chemical rejuvenation of bitumen by FTIR spectrometry (including imaging) and thermogravimetric analysis. A bio-sourced rejuvenating agent was evaluated as well. For the imaging, a mastic polishing method was developed in order to attain as samples as flat as possible for the analysis. The bitumen rejuvenation was observed using FTIR spectroscopy analysis. Several peaks (notably IC=O and IS=O) were observed for bitumen oven aged up to 42 days (long term). It was found that an oven aging period of 14 days was roughly equivalent to bitumen aged by a RTFOT+PAV cycle it terms of rheology and penetration. The mastic (aged for 14 days) was then combined with a bio-sourced agent (at 7.5%w of mastic). It was found by FTIR imaging that the oxidation indicator IS=O, was reduced by the incorporation of the rejuvenating agent
34
Oliveira, Jonathas Rodrigues Salles de. "Modelagem da expansão do concreto devido à RAA com decaimento do módulo de elasticidade." reponame:Repositório Institucional da UFPR, 2013. http://hdl.handle.net/1884/31876.
Abstract:
Resumo: A reação álcali-agregado é uma reação química que ocorre entre os íons alcalinos liberados durante a hidratação do cimento e determinados minerais reativos pertencentes ao agregado. Esta reação provoca a expansão heterogênea do concreto, reduz importantes propriedades do concreto, como as resistências à compressão e à tração e módulo de elasticidade, culminando com a redução da vida útil da estrutura. A modelagem matemática da reação álcali-agregado em uma estrutura sujeita à expansão pode predizer, com grau de precisão apreciável, a movimentação estrutural decorrente da reação, possibilitando programar manutenções, reduzindo o número de paralisações temporárias para correções estruturais e ainda aumentando o grau de segurança das estruturas. Nesta metodologia é apresentada uma modelagem numérica da expansão devido à reação álcali-agregado, utilizando um modelo paramétrico, levando-se em consideração o decaimento do módulo de elasticidade do concreto, aplicado ao programa comercial de elementos finitos ANSYS©, através da rotina programável pelo usuário USERSW. Os resultados obtidos foram validados através de modelos simples com respostas conhecidas.
35
Pereira, Luciano Fabricio Dias. ""Estudo do campo hiperfino magnético na sonda de Ce colocada nos compostos intermetálicos do tipo RAg (R=Terra Rara) e do ordenamento magnético desses compostos usando cálculos de primeiros princípios"." Universidade de São Paulo, 2006. http://www.teses.usp.br/teses/disponiveis/85/85131/tde-28052007-141935/.
Abstract:
Nesse trabalho foram estudados os compostos intermetalicos do tipo RAg (R = Nd, Gd e Ho) por calculos teoricos desenvolvidos dentro do formalismo da Teoria do Funcional Densidade (DFT). O metodo APW+lo (Augmented Planes Waves + lo- cal orbitals) foi aplicado para resolver a equacao de Kohn-Sham e a Aproximacao do Gradiente Generalizado (GGA) usada para tratar de forma aproximada o potencial de troca-correlacao. O codigo computacional utilizado foi o WIEN2k. As atividades foram focalizadas em duas frentes. Numa delas, determinou-se a fase magnetica do estado fundamental dos compos- tos HoAg e NdAg. Para isso, simulou-se as 4 estruturas magneticas possiveis (para as celulas cristalinas cubicas) desses dois sistemas (uma ferromagnetica (0,0,0) e as antifer-romagneticas: (0,0,¼), (¼,¼,0) e (¼,¼,¼)) e com a confeccao de gra¯cos de energia das celulas cristalinas dessas estruturas magneticas pela variacao dos volumes de tais celulas, chegou-se na estrutura magnetica (¼,¼,0) como a mais provavel para o estado fundamental magnetico de ambos os compostos. Tambem observou-se que o sistema de NdAg apre- senta uma pequena diferenca entre as energias das estruturas antiferromagnetica (¼,¼,0) e ferromagnetica. Creditou-se a esse efeito a explicacao de encontrar-se na literatura re- sultados experimentais diferentes para a estrutura magnetica do composto de NdAg puro e dopado com o atomo de 140Ce (entrando no sitio do Nd). Acredita-se que a dopagem do NdAg com o atomo de 140Ce (em uma porcao reduzida), gera alteracao no sinal da integral de troca (acoplamento RKKY), mudando-o de positivo para negativo, e isso implica na modficacao da fase magnetica do estado fundamental, passando da estrutura (¼,¼,0) µa 0,0,0). Assim, com a informacao anterior da estrutura magnetica do composto de NdAg quando dopado com o atomo de 140Ce, entrou-se na segunda etapa do estudo. Nela, fez-se os calculos das estruturas eletronicas usando a aproximacao de supercelulas nos compostos de GdAg e NdAg dopados com o atomo de Ce, garantindo que esse substituisse um atomo de terra rara nas supercelulas cristalinas montadas para determinar no Ce o campo hiperfino magnetico e suas componentes geradoras. Os compostos de GdAg e NdAg (dopados com Ce), respectivamente, tiveram suas celulas cristalinas montadas ferromagnetica e antiferromagneticamente. Utilizou-se a polarizacao orbital (DFT+U) nos eletrons da camada 4f das terras raras (excluindo-se o atomo de Gd que nao apresenta momento angular). Dessa forma, em ambos os sistemas foi possivel fazer varias simulacoes, nas quais a camada 4f do atomo de Ce foi populada de maneiras diferentes, afim de se obter varios valores de momento angular e com isso diversos resultados de campo hiperfino orbital foram conseguidos; assim, automaticamente o campo magnetico hiperfino tambem assumiu diferentes valores. Escolheu-se os sub-estados da camada 4f do Ce para serem simulados por meio da regra de Hund. Como esperado o campo hiperfino magnetico orbital gerado na camada 4f e a principal componente do campo hiper¯no total no atomo de Ce e ele apresenta sinal contrario µa componente de contato. Apesar dos resultados teoricos do campo hiperfino magnetico terem consideravel discrepancia dos resultados experimentais, pode-se verificar que o unico eletron da camada 4f do atomo de Ce (nos dois compostos) possivelmente esta em um dos seguintes sub-estados da camada 4f: ml = ¡2, ml = ¡1 ou ainda uma combinacao dos dois.In this work the magnetic hyper¯ne ¯eld acting on Ce atoms substituting the rare-earths in RAg compounds (R = Gd e Nd) was studied by means of ¯rst-principles electronic structure calculations. The employed method was the Augmented Plane Waves plus local orbitals (APW+lo), embodied in the WIEN2k program, within the framework of the Density Functional Theory (DFT) and with the Generalized Gradient Approximation (GGA) for the exchange and correlation potential. The super-cell approach was utilized in order to simulate for the Ce atoms acting as impurities in the RAg matrix. In order to improve for correlation e®ects within the 4f shells, a Hubbard term was added to the DFT hamiltonian, within a procedure called GGA+U. It was found that the magnetic hyper¯ne ¯eld (MHF) generated by the Ce 4f electron is the main component of the total MHF and that the Ce 4f ground state level is probably a combination of the ml = ¡2 and ml = ¡1 sub-levels. In addition, the ground-state magnetic structure was determined for HoAg and NdAg by observing the behavior of the total energy as a function of the lattice volume v for several possible magnetic ordering in these compounds, namelly, ferromagnetic, and the (0,0,¼), (¼,¼,0) and (¼,¼,¼) types of anti-ferromagnetic ordering of rare-earth atoms. It was found that the ground-state magnetic structure is anti-ferromagnetic of type (¼,¼,0) for both, the HoAg and NdAg compounds. The energy di®erence of the ferromag-netic and antiferromagnetic ordering is very small in the case of the NdAg compound.
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Ahmed, Ananna. "Evaluation of cracking potential of superpave mixtures with high reclaimed asphalt pavement content." Thesis, Kansas State University, 2015. http://hdl.handle.net/2097/20411.
Abstract:
Master of ScienceCivil Engineering
Mustaque A. Hossain
Approximately 89% of 11,000 miles of Kansas roads are surfaced with asphalt. Hundreds of thousands of tons of reclaimed asphalt pavement (RAP) are produced annually in the United States, including in Kansas. This bulk volume of RAP must be economically managed in order to achieve environmental friendliness. Recycling of RAP conserves natural resources and reduces landfill usage. However, many agencies have reported that increased RAP content produces drier hot-mix asphalt (HMA) mixtures than virgin mixtures that are susceptible to premature cracking. In this research, laboratory-produced Superpave HMA mixtures containing increased percentages (20, 30, and 40%) of RAP materials from three RAP sources (Shilling Construction Co., Konza Co., and the Kansas Department of Transportation’s project, US 73) were studied for cracking performance. Mix designs were produced using Superpave design criteria for 12.5-mm nominal maximum aggregate size mixture. The static and repetitive Semicircular Bending (SCB) test, the Texas Overlay Tester test, the dynamic modulus test, and Viscoelastic Continuum Damage (VECD) tests were performed on laboratory-prepared samples. In general, cracking performance decreased with increased RAP content. The RAP from the US 73 project performed most consistently compared to other two sources of RAPs. Test results were analyzed using two-way Analysis of Variance (ANOVA), proving that mixtures containing 4.5% to 4.9% binder performed the best against cracking. The RAP source was found to have more effect on cracking propensity than RAP content. Mixtures with RAP content up to 40% performed satisfactorily. Tukey’s pairwise comparison method was used to compare results from all tests; VECD was determined to be the most appropriate test to evaluate cracking propensity of HMA mixtures.
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Kuester, Scheyla. "Preparação e caracterização de compósitos de poli(estireno-b-etileno-ran-butileno-b-estireno) com grafite expandido." reponame:Repositório Institucional da UFSC, 2013. https://repositorio.ufsc.br/handle/123456789/107240.
Abstract:
Dissertação (mestrado) - Universidade Federal de Santa Catarina, Centro Tecnológico, Programa de Pós-Graduação em Ciência e Engenharia de Materiais, Florianópolis, 2013.Made available in DSpace on 2013-12-05T23:35:13Z (GMT). No. of bitstreams: 1 320900.pdf: 1736514 bytes, checksum: 6678b7c9bb1a6c0096198093b529453c (MD5) Previous issue date: 2013
Compósitos poliméricos condutores de eletricidade (CPCEs) têm recebido especial atenção devido à possibilidade de utilização em várias aplicações tecnológicas. A incorporação de aditivos condutores, tais como, grafite expandido (GE) e negro de fumo condutor (NFC), em matrizes de elastômeros termoplásticos é uma alternativa bastante interessante para a produção de CPCEs, com propriedades mecânicas semelhantes às de uma borracha vulcanizada, sem a necessidade do uso de agentes de vulcanização. Neste trabalho, foram preparados compósitos de poli(estireno-b-etileno-ran-butileno-b-estireno) (SEBS) com GE ou NFC, a partir de um reômetro de torque. Primeiramente, foram realizados estudos com frações previamente determinadas e fixadas de aditivos condutores, e definidos os parâmetros de processamento dos compósitos através de dados obtidos pelo reômetro de torque e de valores de condutividade elétrica obtidos pelo método padrão quatro pontas. Posteriormente, compósitos com diferentes frações em massa de SEBS e aditivos condutores foram obtidos e caracterizados a partir das técnicas i) condutividade elétrica método padrão duas e quatro pontas e ii) reometria de placas paralelas. A morfologia dos aditivos e compósitos foi avaliada a partir de imagens obtidas por microscopia eletrônica de varredura (MEV). Foi, também, estudada a viabilidade da utilização dos compósitos de SEBS/GE para blindagem eletromagnética, e comparada a eficiência de blindagem desses materiais com a dos compósitos de SEBS/NFC.
Abstract : Electrically conductive polymer composites (CPCEs) have received special attention due to the possibility of use in various technological applications. The addition of conductive additives, such as expanded graphite (EG) and conductive carbon black (NFC) in thermoplastic elastomer matrix is a very interesting alternative for the production of CPCEs with mechanical properties similar to those of a vulcanized rubber without the need for the use of vulcanising agents. In this work, composites of poly (styrene-b-ethylene-ran-butylene-b-styrene) (SEBS) with GE or NFC were prepared in a torque rheometer. First, studies were performed with predetermined and fixed fractions of conductive additives, and set the parameters of composites processing through data obtained by a torque rheometer and electrical conductivity values obtained by four-point probe method. Subsequently, composites with different mass fractions of SEBS and conductive additives were obtained and characterized from the techniques i) electrical conductivity by four-point probe method and ii) parallel plate rheometry. The morphology of additives and composites was evaluated from images obtained by scanning electron microscopy (SEM). It was also studied the feasibility of using the SEBS/GE composite for electromagnetic shielding, and its shielding efficiency was compared with the shielding efficiency of the SEBS/NFC composite.
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Cooley, Dane A. "Effects of Reclaimed Asphalt Pavement on Mechanical Properties of Base Materials." Diss., CLICK HERE for online access, 2005. http://contentdm.lib.byu.edu/ETD/image/etd1094.pdf.
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Duan, Ran [Verfasser], Lorenz [Akademischer Betreuer] Singheiser, and Brita Daniela [Akademischer Betreuer] Zander. "Prediction of oxidation induced life time for FCC materials at high temperature operation / Ran Duan ; Lorenz Singheiser, Brita Daniela Zander." Aachen : Universitätsbibliothek der RWTH Aachen, 2017. http://d-nb.info/1162845953/34.
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Esteves, Teresa do Carmo Botelho. "Uso de cinzas volantes da queima de biomassa na mitigação da RAS." Master's thesis, Universidade de Aveiro, 2010. http://hdl.handle.net/10773/4336.
Abstract:
Mestrado em Engenharia de MateriaisSão sobejamente conhecidas, as ruinosas degradações que as grandes estruturas de betão sofrem ao longo do tempo. Também já foram identificadas algumas causas desta inexorável acção degenerativa e há muito tempo que se equacionam os elevados prejuízos que elas acarretam. Neste trabalho estudou-se o efeito de cinzas da queima de biomassa na mitigação da reacção álcalis-sílica expansiva (RAS). Esta reacção é lenta mas progressiva e leva à degradação de muitas edificações executadas com um dos materiais de construção mais usados nos nossos dias. Este trabalho pode ser dividido em duas partes. Na primeira parte fez-se a caracterização física e química das cinzas provenientes de duas unidades industriais situadas na zona centro de Portugal: (i) termoeléctrica da queima de biomassa (C1), (ii) co-geração da indústria de celulose (C2). Verificou-se que as cinzas C1 são mais finas que as cinzas C2. Devido ao baixo teor de inqueimados nas cinzas C2, pode-se concluir que a tecnologia de queima da indústria de celulose é mais eficiente. Na segunda parte deste trabalho, estudou-se a substituição de cimento por cinzas de biomassa em teores de 20, 30 e 40%, em argamassas cimentíceas, para tentar mitigar a reacção expansiva. Constactou-se que as argamassas com a incorporação das cinzas C1 sofreram menos expansão do que as argamassas com a incorporação de cinzas C2. As argamassas com a incorporação de cinzas e metacaulino mostraram ser eficazes na mitigação da RAS.
The ruinous degradation of large concrete structures over time is well known. One possible cause is due to the reaction between cement past and aggregates, since it causes a significant expansion at later ages, this process is known as alkali-silica reaction (ASR) and a long ago equated the huge losses. In this work it was studied the effect of fly ash from biomass combustion in the mitigation of the reaction alkali-silica expansion. This reaction is slow but progressive that leads to the degradation of many buildings built with the construction material most used in our days. This work can be split in two parts. In the first one we characterize the physical and chemical proprieties of fly ashes generated two industrial plants situated in the center area of Portugal: (i) biomass thermal combustion (C1), (ii) co-generation plant of cellulose (C2). It was found that the ashes C1 are more fine the ashes C2. Due to low organic matter in the ash C2, we concluded that the burning technology of the cellulose industry is more efficient. In the second part of the work we studied mortars were the cement was substituted by biomass fly ash (at levels 20, 30 and 40%) in trying to mitigate the ASR expansive behaviour. It was found that the mortar with the incorporation of ash C1 expanded less than the mortar with the incorporation of ash C2. The mortar with the incorporation of ash and metakaolin proved to be effective in the mitigation of ASR.
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Bobba, Venkata Nagamalli Koteswara Rao. "High Fidelity Raman Chemical Imaging of Materials." Cleveland State University / OhioLINK, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=csu1462806523.
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McCalla, M. Katherine. "The role of maternal behavior and toddler compliance in the development of problem behaviors." View electronic thesis (PDF), 2009. http://dl.uncw.edu/etd/2009-2/rp/mccallam/mmccalla.pdf.
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Mizumoto, Camilo [UNESP]. "Investigação da reação álcali-agregado (RAA) em testemunhos de concreto e agregados constituintes." Universidade Estadual Paulista (UNESP), 2009. http://hdl.handle.net/11449/91463.
Abstract:
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mizumoto_c_me_ilha.pdf: 6141199 bytes, checksum: d708c1fab69dfe7948269a1d6ffae9a2 (MD5)Fundação de Ensino Pesquisa e Extensão de Ilha Solteira (FEPISA)
A reação álcali-agregado (RAA) é um fenômeno expansivo que ocorre em diversas estruturas de concreto que vivenciam freqüentes condições de umidade. O princípio desta reação fundamenta-se em interações químicas entre a sílica constituinte do agregado e os álcalis presentes no concreto, em presença de umidade. O produto formado é um “gel” expansivo que ocasiona processos de fissuração e deslocamentos diferenciais em estruturas de concreto. Atualmente, vários centros de pesquisa têm estudado diversas formas de diagnosticar a presença da reação em estruturas degradadas e avaliar previamente o potencial reativo dos agregados empregados nas obras civis. Os métodos comumente empregados na avaliação da RAA envolvem ensaios laboratoriais normalizados pela NBR 15577 (ABNT, 2008) e técnicas qualitativas de campo. Dentre estas técnicas destaca-se o teste da mancha, que identifica a presença da reação de forma imediata pela formação de tonalidades características em regiões afetadas do concreto. Neste contexto, a presente pesquisa objetivou investigar a RAA em testemunhos de concreto e em diferentes litologias de agregado por análises laboratoriais e técnicas qualitativas. No trabalho desenvolvido foi estudada a composição físico-química de produtos extraídos da RAA e dos materiais componentes dos testemunhos, além de estudos da reatividade potencial dos agregados constituintes por análises mineralógicas e ensaios acelerados de argamassa e concreto, sendo complementados por estudos microestruturais e testes qualitativos (método da mancha). Os resultados mostraram a diversidade na composição de xerogéis da RAA e incompatibilidades nos resultados dos ensaios de reatividade em agregados. Os testes colorimétricos apresentaram um desempenho satisfatório no indicativo da RAA, além de distinguir a presença de outras manifestações patológicas nos concretos e compósitos estudados
The alkali-aggregate reaction (AAR) is an expansion phenomenon that occurs in diverse concrete structures that live in frequently conditions of humidity. The principle of this reaction is based on chemical interactions between the constituent yield of the aggregate and the alkalis of the concrete, in humidity presence. The created product is an expansion gel that generates processes of cracking and differential displacements in concrete structures. Nowadays, many research centers have studied diverse forms to diagnose the presence of the reaction in degraded structures and to previously evaluate the potential reactivity of aggregates used in civil buildings. The common methods used in the evaluation of the RAA involved laboratory assays normalized by NBR 15577 (ABNT, 2008) and qualitative techniques of yield. Among these techniques, the staining method detached which identifies the presence of the reaction of immediate form for the formation of characteristic shade in affected regions of the concrete. In context, the present research objectified to investigate the AAR in concrete core and different lithology of aggregate, being approached laboratory assays and qualitative techniques. It was studied the composition physical-chemistry of extracted products of the AAR and the component materials of concrete core, besides studies of the potential reactivity of constituent aggregates for mineralogical assays and mortar bar test and concrete prisms. Also complemented by microstructure studies and qualitative tests (staining method).The results showed diverseness composition of xerogels of the AAR and incompatibilities in the results of the reactivity assays in aggregates. The staining tests showed satisfactory performances in the indicative of the AAR with regard of the presence of other pathological manifestations in concrete and cement composites
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Almeida, Wagner José de. "Otimização estrutural de protótipos fabricados pela tecnologia FDM utilizando o método dos elementos finitos." Universidade de São Paulo, 2007. http://www.teses.usp.br/teses/disponiveis/18/18146/tde-05022010-163333/.
Abstract:
Este trabalho tem como objetivo principal a otimização dos protótipos fabricados pelo processo FDM (Fused Deposition Modeling) em procedimento baseado na análise do comportamento estrutural dos protótipos variando as estratégias de preenchimento das camadas. Para atingir tal objetivo, corpos de prova com diferentes orientações de preenchimento foram ensaiados experimentalmente e os resultados foram verificados em análise estrutural por elementos finitos. Foram verificados o caráter ortotrópico do material do protótipo e a validade do uso da Teoria Clássica dos Laminados na simulação de seu comportamento. Os conceitos e metodologia de análise foram validados em estudos de casos, mostrando a viabilidade de sua aplicação na obtenção de protótipos funcionaisThe objective of this work is to develop an optimization procedure for FDM prototypes. This procedure is based on the structural analysis of the prototypes within different slice filling paths. In order to reach this objective, experimental tests with different filling trajectories are conducted and the results are used in structural analysis by finite element method. The orthotropic behavior of the prototype material and the use of the Classical Laminate Theory in the numerical simulation were validated. The results were applied in different case studies, showing the viability of its application in the design of functional prototypes.
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Rodrigues, Manuella Karla da Cruz. "Estudo da viabiliza??o do uso da mistura h?brida ferrocarbonila / ferrita de NI0,5Zn0,5Fe2o4 como material absorvedor de radia??o eletromagn?tica." Universidade Federal do Rio Grande do Norte, 2010. http://repositorio.ufrn.br:8080/jspui/handle/123456789/17652.
Abstract:
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Previous issue date: 2010-08-31Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior
Were synthesized ferrites of NiZn on systems Ni0,5Zn0,5Fe2O4, the precursors citrate method. The decomposition of the precursors was studied by thermogravimetric analysis and spectroscopy in the infrared region, the temperature of 350?C/3h. The evolution of the phases formed after calcinations at 350?C/3h, 600, 1000 and 1100?C/2h was accompanied by X-ray diffraction using the Rietveld refinement method for better identification os structures formed. Was observed for samples calcined at different temperatures increased crystallinity with increasing calcination temperature, being observed for the samples calcined at 900 and 1100 ? C/2h was the precipitation of a secondary phase, the phase hematite. The ferrocarbonila of industrial origin was analyzed by X-ray diffraction and Rietveld for the identification of its structure. The carbonyl iron was added NiZn ferrite calcined at 350?C/3h, 600, 900, 1000 and 1100?C/2h to the formation of hybrid mixtures. They were then analyzed by Xray diffraction and Rietveld. The NiZn ferrite and ferrocarbonila as well as the hybrid mixtures were subjected to analysis of scanning electron microscopy, magnetic measurements and reflectivity. The magnetic measurements indicated that the ferrite, the ferrocarbonila, as well as hybrid mixtures showed characteristics of soft magnetic material. The addition of ferrocarbonila in all compositions showed an increase in the results of magnetic measurements and reflectivity. Best result was observed in the increase of the magnetization for the hybrid mixture of Ferrocarbonila / ferrite of NiZn calcined at 600?C/2h. The mixture Ferrocarbonila / ferrite calcined 1000?C/2h presented better absorption of electromagnetic radiation in the microwave
Foram sintetizadas ferritas de NiZn no sistema Ni0,5Zn0,5Fe2O4, pelo m?todo dos citratos precursores. A decomposi??o dos precursores foi estudada por an?lise termogravim?trica e espectroscopia na regi?o do infravermelho na temperatura de 350?C/3h. A evolu??o das fases formadas ap?s calcina??es a 350?C/3h, 600, 1000 e 1100?C/2h foi acompanhada por difra??o de raios X utilizando o refinamento de Rietveld para melhor identifica??o das estruturas formadas. Foi observado para as amostras calcinadas em diferentes temperaturas o aumento da cristalinidade com o aumento da temperatura de calcina??o, sendo verificado que para as amostras calcinadas a 900 e 1100?C/2h ocorreu a precipita??o de uma fase secund?ria, a fase hematita. A ferrocarbonila de proced?ncia industrial foi analisada por Difra??o de raios X e por Rietveld para a identifica??o de sua estrutura. A ferrocarbonila foi adicionada ? ferrita de NiZn calcinada a 350?C/3h, 600, 1000 e 1100?C/2h para a forma??o das misturas h?bridas. Em seguida foram analisadas por difra??o de raios X e por Rietveld. A ferrita de NiZn, a ferrocarbonila, assim como as misturas h?bridas foram submetidas ? an?lises de Microscopia Eletr?nica de Varredura, medidas magn?ticas e refletividade. As medidas magn?ticas indicaram que a ferrita, a ferrocarbonila, como tamb?m as misturas h?bridas apresentaram caracter?sticas de material magn?tico macios. A adi??o de ferrocarbonila em todas as composi??es indicou um aumento nos resultados de medidas magn?ticas e de refletividade. Foi verificado melhor resultado no aumento da magnetiza??o para a mistura h?brida de Ferrocarbonila/ferrita de NiZn calcinada 600?C/2h. A mistura Ferrocarbonila/ferrita calcinada 1000?C/2h apresentou melhor resultado absor??o da radia??o eletromagn?tica na faixa de microondas em rela??o ?s outras misturas
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Bittar, Telmo Oliveira. "Estudo dos efeitos do material particulado proveniente da biomassa de cana-de-açúcar sobre o aparelho respiratório e circulatório de ratos wistar combinados ou não com a infecção estafilocócica." [s.n.], 2013. http://repositorio.unicamp.br/jspui/handle/REPOSIP/290144.
Abstract:
Orientador: Antonio Carlos PereiraTese (doutorado) - Universidade Estadual de Campinas, Faculdade de Odontologia de Piracicaba
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Resumo: Inúmeros relatos da literatura apontam para associações entre poluição atmosférica e patologias do aparelho respiratório e cardíaco. O objetivo deste estudo foi averiguar os efeitos do material particulado oriundo da queima da biomassa da cana-de-açúcar no aparelho respiratório e cardíaco de ratos machos wistar. Utilizou-se de um forno especialmente desenhado para coletar o material particulado proveniente da palha da cana de- açúcar e então isolá-lo. Sua análise química foi feita por cromatografia gasosa. Posteriormente foram alocados 4 grupos, de 7 ratos cada, dividindo-os na seguinte ordem: grupo I- recebeu instilação de material particulado em soro fisiológico; grupo II- recebeu instilação de material particulado e S. aureus; grupo III- controle, recebeu apenas instalação de soro fisiológico; grupo IV- recebeu apenas instilação de S. aureus. Após o período de uma semana, os animais foram eutanasiados, e foram coletadas amostras de pulmão, traquéia e coração para análise histológica, morfométrica e de imunoensaio. A metodologia utilizada para análise histológica e morfométrica foi a de comparação ao padrão de normalidade, e teste ELISA de captura no imunoensaio para as seguintes citocinas: GRO-?, IL-1?, IL-1?, IL-6, IFN-?, TNF-?. Os resultados analisados mostraram que o principal componente encontrado no material particulado de cana de açúcar foi o éster de ácido ftálico. Não houve nenhuma alteração estatística entre os grupos em relação ao tecido cardíaco. A análise histológica revelou alteração no padrão de normalidade apenas no grupo IV. Na análise morfométrica da traquéia, foi observada uma redução no espessamento do tecido conjuntivo no grupo II, e nas medidas de centro, todos os grupos apresentaram diferenças significativas em relação ao controle. Em relação ao imunoensaio, observou-se que os grupos I e II expressaram a liberação de IL-1? em relação ao controle. O grupo I apresentou expressão significativa de IL-6 em relação ao controle e grupo IV, e de IL-1 ? e IFN-? com relação aos demais grupos. Deste modo, o presente estudo mostrou que o material particulado, oriundo da queima da biomassa da cana-de-açúcar, é capaz de provocar alteração no aparelho respiratório de ratos wistar e motivar a produção de citocinas
Abstract: Several studies point out the association between atmospheric pollution and pathologies from respiratory and cardiac systems. The aim of this study was to analyze the effects of the particulate matter from sugar cane biomass in respiratory and cardiac systems of male wistar rats. It was used a special developed oven to collect the sugar cane particulate matter and so isolate it. Its chemical analysis was done by gas chromatography. Later it was allocated 4 groups each one with 7 rats been divided into: group I- received instillation of only particulate mater in physiological saline; group II- received particulate matter plus S. aureus; group III- control group with only physiological saline; group IV- received only S. aureus. After one week, the animals were euthanized and samples were gathered from lung, heart and trachea tissues to histological, morphometric and immunoassays analysis. The histological and morphometric employed methodology was the normality standard variation and ELISA capture test for immunoassays for the following cytokines: GRO-?, IL-1?, IL-1?, IL-6, IFN-?, TNF-?. Analyzed results shown the main substance found in sugar cane particulate matter was phthalic acid ester. None standard variation statically for heart tissue was found. Histological analysis revealed changes in the normal pattern only in group IV. In trachea morphometric analysis it was observed the decreasing in its conjunctive tissue width for group II, and in its center measurement all the groups presented significant difference when compared to control group. In the immunoassays it was noted that group I and II expressed the production of IL-1? when compared to control group. The group I presented a significant expression of IL-6 compared to control group and group IV; and IL-1 ? e IFN-? when compared to the other groups. Based on this achieves, the present study has shown the sugar cane particulate matter is capable to produce alteration in respiratory system of wistar rats and motivate cytokines production
Doutorado
Saude Coletiva
Doutor em Odontologia
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Mizumoto, Camilo. "Investigação da reação álcali-agregado (RAA) em testemunhos de concreto e agregados constituintes /." Ilha Solteira : [s.n.], 2009. http://hdl.handle.net/11449/91463.
Abstract:
Orientador: Antonio Anderson da Silva SegantiniBanca: Selmo Chapira Kuperman
Banca: Marcelo Ornaghi Orlandi
Resumo: A reação álcali-agregado (RAA) é um fenômeno expansivo que ocorre em diversas estruturas de concreto que vivenciam freqüentes condições de umidade. O princípio desta reação fundamenta-se em interações químicas entre a sílica constituinte do agregado e os álcalis presentes no concreto, em presença de umidade. O produto formado é um "gel" expansivo que ocasiona processos de fissuração e deslocamentos diferenciais em estruturas de concreto. Atualmente, vários centros de pesquisa têm estudado diversas formas de diagnosticar a presença da reação em estruturas degradadas e avaliar previamente o potencial reativo dos agregados empregados nas obras civis. Os métodos comumente empregados na avaliação da RAA envolvem ensaios laboratoriais normalizados pela NBR 15577 (ABNT, 2008) e técnicas qualitativas de campo. Dentre estas técnicas destaca-se o teste da mancha, que identifica a presença da reação de forma imediata pela formação de tonalidades características em regiões afetadas do concreto. Neste contexto, a presente pesquisa objetivou investigar a RAA em testemunhos de concreto e em diferentes litologias de agregado por análises laboratoriais e técnicas qualitativas. No trabalho desenvolvido foi estudada a composição físico-química de produtos extraídos da RAA e dos materiais componentes dos testemunhos, além de estudos da reatividade potencial dos agregados constituintes por análises mineralógicas e ensaios acelerados de argamassa e concreto, sendo complementados por estudos microestruturais e testes qualitativos (método da mancha). Os resultados mostraram a diversidade na composição de xerogéis da RAA e incompatibilidades nos resultados dos ensaios de reatividade em agregados. Os testes colorimétricos apresentaram um desempenho satisfatório no indicativo da RAA, além de distinguir a presença de outras manifestações patológicas nos concretos e compósitos estudados
Abstract: The alkali-aggregate reaction (AAR) is an expansion phenomenon that occurs in diverse concrete structures that live in frequently conditions of humidity. The principle of this reaction is based on chemical interactions between the constituent ���� yield���� of the aggregate and the alkalis of the concrete, in humidity presence. The created product is an expansion gel that generates processes of cracking and differential displacements in concrete structures. Nowadays, many research centers have studied diverse forms to diagnose the presence of the reaction in degraded structures and to previously evaluate the potential reactivity of aggregates used in civil buildings. The common methods used in the evaluation of the RAA involved laboratory assays normalized by NBR 15577 (ABNT, 2008) and qualitative techniques of ���� yield. Among these techniques, the staining method detached which identifies the presence of the reaction of immediate form for the formation of characteristic shade in affected regions of the concrete. In context, the present research objectified to investigate the AAR in concrete core and different lithology of aggregate, being approached laboratory assays and qualitative techniques. It was studied the composition physical-chemistry of extracted products of the AAR and the component materials of concrete core, besides studies of the potential reactivity of constituent aggregates for mineralogical assays and mortar bar test and concrete prisms. Also complemented by microstructure studies and qualitative tests (staining method).The results showed diverseness composition of xerogels of the AAR and incompatibilities in the results of the reactivity assays in aggregates. The staining tests showed satisfactory performances in the indicative of the AAR with regard of the presence of other pathological manifestations in concrete and cement composites
Mestre
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Amorim, João Paulo de Arruda 1981. "Caracterização do comportamento materno e suas implicações no desenvovimento fisico,na função reprodutiva e no perfil hormonal da prole feminina de ratas UChA e UChB (consumidoras voluntárias de etanol a 10%)." [s.n.], 2012. http://repositorio.unicamp.br/jspui/handle/REPOSIP/317536.
Abstract:
Orientadores: Francisco Eduardo Martinez, Wilson de Mello JuniorTese (doutorado) - Universidade Estadual de Campinas, Instituto de Biologia
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Resumo: Estudos realizados com mães dependentes de etanol demonstraram que elas apresentam maior dificuldade em cuidar de suas crianças, quando comparadas às mães não dependentes, evidenciando um distúrbio no comportamento materno durante o período pós-natal, que corresponde ao período onde as primeiras ligações sociais do animal são formadas e o organismo está muito sensível aos efeitos de estímulos ambientais. Vários estudos têm documentado as conseqüências do uso de etanol durante a gestação para a saúde do infante, porém pouca atenção tem sido dada à relação materno-infantil em mulheres alcoólicas durante o período pós-natal e as consequências dessa relação para prole feminina na vida adulta. O presente trabalho teve o objetivo de caracterizar o comportamento materno das ratas da variedade consumidora de etanol (UChA e UChB) e verificar as influências da variação do comportamento materno no desenvolvimento físico, na função reprodutiva e no status hormonal da prole feminina. O comportamento foi avaliado observando os seguintes parâmetros: carregar, lamber, amamentar com o dorso arcado e lamber, amamentar com o dorso arcado, amamentar passivamente e não contato com a prole. A avaliação do desenvolvimento físico da prole feminina considerou o dia do nascimento dos pêlos, da abertura dos olhos e do descolamento de orelhas. Para avaliar o desenvolvimento sexual inicial foram analisados os dias da abertura vaginal e idade do primeiro e segundo estro. A função reprodutiva foi avaliada pela regularidade de ciclo estral, pela expressão dos receptores AR, ER-? e ER-? no ovário e pelo perfil hormonal da prole feminina (níveis plasmáticos de FSH, LH, 17?-estradiol, progesterona e corticosterona). As fêmeas UChA apresentaram maiores frequências dos comportamentos de carregar, de lamber/limpar e de amamentar os filhotes. Mães muito cuidadosas apresentaram concentrações elevadas de corticosterona e 17?-estradiol. A prole UChA apresentou maior ganho de peso corporal, aceleração da abertura dos olhos, da abertura vaginal, da instalação da puberdade e sincronização do ciclo estral. A prole feminina que recebeu baixo cuidado materno (UChB) revelou maior duração do ciclo estral, aumento das concentrações de corticosterona e 17?-estradiol e de seus receptores ovarianos (ER-? e ER-?), maior peso dos ovários, maior número de folículos primordiais, antrais e maduros e mais imunomarcações positivas do Ki67 nos folículos ovarianos. Concluímos que a variedade de ratas UChB, apresenta acentuada variação do comportamento materno, sendo classificada como mãe pouco cuidadosa e essa variação do cuidado materno afeta diretamente o desenvolvimento físico, a instalação da puberdade, os níveis hormonais, desregula o ciclo estral e a foliculogênese e regula diferencialmente a expressão dos receptores ER-? e ER-? nos ovários de ratas adultas
Abstract: Studies focused on drug-dependent mothers (mainly ethanol-dependent mothers) have demonstrated that there is an enormous difference in the care of their children compared to non-dependent mothers, showing an disorder in maternal behavior during the postnatal period, which corresponds to the period where the first social bonds are formed and the animal's organism is very sensible to the effects of environmental stimuli. Various studies have documented the consequences of ethanol use during pregnancy for the health of the infant, but little attention has been given to the mother-child relationship in alcoholic female during the postnatal period and the consequences of this relationship to female offspring in adulthood. The aim of the present work is to evaluate maternal care in ethanol-preferring rats (UChA and UChB) and its effects on physical development, in sexual function and in status hormones in female offspring. The behavior was evaluated by observing the following parameters: carry, licking/grooming, arched-back nursing and licking/grooming, arched-back nursing, passive nursing, contact and not with the pups. The evaluation of the physical development of the female offspring considered the day of birth of hair, eye opening and detached ears. To evaluate the early sexual development were analyzed days of vaginal opening and age of first and second estrous. The reproductive function was evaluated by the regularity of the estrous cycle, the expression of receptors AR, ER-? and ER-? in the ovary and the hormonal status of female offspring (plasma levels of FSH, LH, 17?-estradiol, progesterone and corticosterone). UChA mothers showed higher frequencies of carrying, licking/grooming and nursing the pups. Mothers high care evidencing the highest plasma corticosterone levels and 17?-estradiol. The UChA offspring showed greater body weight gain, accelerated eye opening, vaginal opening, the installation and synchronization of estrous cycle. The female offspring who received low maternal care (UChB) showed an increase of the estrous cycle, concentrations of corticosterone and 17?-estradiol and ovarian receptors (ER-? and ER-?, higher ovarian weight and increased number of primordial, antral and mature follicles and higher Immunoreactivity for Ki-67 in the ovarian follicles. We conclude that UChB rats show marked variations in maternal care, being classified as low maternal care and the variation of maternal care directly affects the physical, the installation of puberty, hormone levels, deregulate the estrous cycle and folliculogenesis and differentially regulates the expression of receptors ER-? and ER-? in the ovaries of adult rats
Doutorado
Anatomia
Doutor em Biologia Celular e Estrutural
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CIRILLI, SARA. "La spettroscopia di riflettanza anisotropa (ras) applicata allo studio di strati ultra-sottili di porfirine depositati su grafite in ultra-alto vuoto." Doctoral thesis, Università degli Studi di Roma "Tor Vergata", 2010. http://hdl.handle.net/2108/1211.
Abstract:
L'argomento della tesi di dottorato è la realizzazione di strati ultra-sottili di porfirine su substrato cristallino mediante evaporazione in Ultra Alto Vuoto (UHV), e il loro studio con una particolare tecnica ottica, la Spettroscopia di Riflettanza Anisotropa (RAS: Reflectance Anisotropy Spectroscopy), che ne permette la caratterizzazione in situ e in tempo reale. Il lavoro sperimentale ha riguardato dapprima il completo allestimento della camera UHV per la crescita degli strati organici, poi il raggiungimento delle condizioni necessarie alla deposizione, infine lo studio mediante RAS dei layer ottenuti.
Nonostante i film sottili organici siano ormai da anni sotto l’attenta indagine di chimici, biologi e fisici, importanti interrogativi riguardo il controllo del processo di deposizione su un substrato e su quali siano le interazioni che governano la formazione delle strutture molecolari (dalle quali dipendono le proprietà ottiche ed elettroniche del campione) rimangono ancora oggi senza soddisfacenti risposte. Si può facilmente comprendere quindi l’importanza di questa problematica scientifica qualora si vogliano utilizzare i materiali organici per sviluppare la cosiddetta tecnologia “soft” di ultima generazione.
In questa tesi, è stata fatta la scelta significativa di individuare un sistema “modello” molecola+substrato (in particolare una porfirina a base libera -H2TPP- su substrato di grafite HOPG), per ridurre all'essenziale le problematiche di un sistema spesso estremamente complesso tanto nella parte sperimentale quanto nell'interpretazione dei dati sperimentali. I risultati ottenuti dimostrano il raggiungimento delle condizioni di crescita necessarie per ottenere singoli strati ordinati di porfirine a due diverse temperature del substrato (300 K e 140 K), come avvalorato -nel primo caso- dalle immagini STM prese sugli stessi campioni, individuando la caratteristica forma di riga per l'anisotropia ottica associata alla fase ordinata.
Inoltre, sulla base dei dati è stato sviluppato in modo originale un modello interpretativo della particolare anisotropia misurata con la RAS, riconducendola alle caratteristiche interazioni che si instaurano tra molecole adiacenti nello strato sottile, dando così una risposta “semplice” e di immediato senso fisico ad un problema affrontato in letteratura ricorrendo a calcoli di notevole complessità e non facile verifica sperimentale.English Abstract: The main subject of this PhD thesis is the deposition of ultra-thin porphyrin layers on a crystal substrate, by means of evaporation in Ultra High Vacuum (UHV), and their study by a particular optical spectroscopy, Reflectance Anisotropy Spectroscopy (RAS) capable to characterize the layer in situ and in real-time. The experimental work initially dealt with the setting up of the UHV chamber dedicated to the growth of the organic layers; after that, the work focused on the optimization of growth conditions to achieve optimal deposition of the organic layer; the thin layers were then investigated by RAS. Organic thin films have been deeply studied since several years by chemists, biologists and physicists. Nevertheless, major issues regarding the control of deposition as well as the interactions driving molecular arrangements on a substrate still remain unclear. These topics are of basic importance to move towards “soft” technology based on organic materials: as a matter of fact, electronic and optical properties of organic films are closely related to molecule arrangements in the layer. In this Thesis a “model system” molecule + substrate is proposed (more specifically a free base porphyrin -H2TPP- on a graphite substrate -HOPG-) in order to simplify the study both on a practical point of view and for what concerns experimental data. The results demonstrate that it is possible to tune growth parameters so that ordered single layers of porphyrins can be deposited on HOPG at two different substrate temperatures (300 K and 140 K), as also confirmed -for the higher temperature- by STM imaging. Correspondingly, a characteristic lineshape of the RAS signal is observed and directly related to the ordered arrangement of the molecules on the substrate. Furthermore, we developed an original model which allows interpreting the anisotropy signal measured by RAS in terms of typical interactions between adjacent molecules in the thin organic layer. The model allows a straightforward explanation of the optical data. As a consequence, it seems to be possible to provide a simple result (and a direct physical meaning) to a problem, which has been already addressed in the scientific literature but, unfortunately, with highly complex computations and without an easy experimental verification, yet.
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PEREIRA, LUCIANO F. D. "Estudo do campo hiperfino magnético na sonda de Ce colocada nos compostos intermetálicos do tipo Rag(R=terra rara) e do ordenamento magnético desses compostos usando cálculos de primeiros princípios." reponame:Repositório Institucional do IPEN, 2006. http://repositorio.ipen.br:8080/xmlui/handle/123456789/11444.
Abstract:
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Dissertação (Mestrado)
IPEN/D
Instituto de Pesquisas Energeticas e Nucleares - IPEN-CNEN/SP