Dissertations / Theses on the topic 'CFRCs'

Les besoins d’allègement de poids dans le transport principalement en vue d’une réduction des émissions des gaz à effet de serre placent les composites à renfort de fibres de carbone (CFRC) comme matériaux potentiels. La fonctionnalisation de ces matériaux leur confèrerait une valeur ajoutée et de nouvelles perspectives d’application. La fonctionnalisation des composites CFRC implique de nombreux travaux de recherche qui se heurtent à une problématique de la décohésion du dépôt de surface en raison de la faible adhérence CFRC-dépôt, car les deux parties étant respectivement en polymère et en métal. Ce problème est un verrou scientifique. L’objectif de ce travail de thèse est alors de mettre au point une solution de fonctionnalisation de surface d’un composite CFRC par une technique de métallisation par collision à haute vitesse. Une partie des travaux effectués consiste à développer une structure composite hybride constituée d’une structure CFRC et d’une sous-couche composée d’une phase métallique et d’une phase polymère calibrée pour compatibiliser la structure CFRC et la technique de métallisation par projection à froid.Une partie de ce travail de thèse est consacrée à l’élaboration d’un système hybride CFRC/sous-couche biphasique superficielle en polymère/métal. Le procédé d’infusion sous vide a été mis en œuvre pour la polymérisation de ce système. La sous-couche biphasique consiste en un mélange de poudre micrométrique métallique avec de la résine thermodurcissable (époxy) ou thermoplastique (poly méthacrylate de méthyle) à différentes concentrations, permettant de produire des sous-couches de type TS-Al, TS-Cu, ou TP-Cu directement intégrées à la surface de la structure CFRC. Des essais de métallisation de ces sous-couches par projection à froid ont ensuite été réalisés, en utilisant le système de projection à basse pression Dymet 423. Des poudres de cuivre, d’aluminium, de zinc et d’étain sont choisies comme matériau de métallisation en raison de leur bonne conductivité électrique et thermique. Des poudres composites constituées d’un mélange métal/alumine ont aussi été considérées pour améliorer la formation de revêtement en tirant profit de l’effet de martelage produit par les particules d’alumine. Un revêtement (Sn + Al2O3) d’une épaisseur de 60 µm a été obtenu sur la sous-couche TS-Cu, démontrant en cela la faisabilité d’une métallisation d’une structure CFRC via la sous-couche biphasique, par projection à basse pression.Une autre partie de cette thèse porte sur une analyse phénoménologique de la réponse mécanique de la sous-couche biphasique TS en utilisant la simulation numérique. La collision à haute vitesse endommage la sous-couche à matrice thermodurcissable qui se fragmente sous l’effet de la contrainte de collision. Ce phénomène explique la difficulté de formation de revêtement sur la sous-couche à base de polymère thermodurcissable. Afin d’identifier des matériaux polymères appropriés pour une bonne tenue mécanique de la sous-couche pendant la collision à haute vitesse, une simulation sur des substrats thermoplastiques (TP et TP-Cu) a été étudiée. Les résultats montrent une pénétration des particules de Cu projetées, dans le substrat TP, en formant en cela une adhésion métal/résine par ancrage mécanique. Les particules de Cu constituant la sous-couche permettent de favoriser la déformation plastique des particules de Cu projetées, et ensuite la formation d’un revêtement. Ce constat a permis d’élaborer des essais expérimentaux de projection à froid à haute pression pour métalliser des substrats à base de matrice TP. Il en résulte une formation de revêtement pour différentes poudres (Cu sphérique, Cu dendritique, Cu + Al2O3). Le revêtement obtenu peut atteindre une épaisseur de 95 µm, 231 µm et 114 µm respectivement. Ces résultats démontrent bien la faisabilité d’une métallisation d’une structure CFRC via une sous-couche biphasique TP et une technique additive par projection à froid à haute pression
Carbon fiber reinforced composites (CFRC) have been successfully developed since decades as efficient and lightweight materials for various innovative applications and mostly for transport applications. Due to the low electrical conductivity of the polymer matrix of CFRCs, a better functionalization of such materials, such as developing a metallic coating on the CFRC structure of an aircraft, brings added values that contribute to a longer life and new performances such as the lightning strike protection (LSP) performance. The major objective of this PhD research program is to improve the metallization of a CFRC substrate by a new approach that focuses on the development of a hybrid layered structure made of CFRC and a biphasic sublayer embedded onto the top surface of this structure, prior to a cold spray metallization. To achieve this objective, the research works rely on an experimental task and a computational analysis which can be divided into three significant contributions:The first experimental part focuses on the development of a biphasic sublayer in between the CFRC substrate and the metal coating. This sublayer consists of a mixture of a polymer (Thermoset Epoxy, Thermoplastic Polymethyl methacrylate) with a micron sized metal powder (Al, Cu). The vacuum assisted resin infusion process is used to produce the hybrid CFRC with the biphasic sublayer on its top face. Prior to the cold spray metallization, the thermo-physical properties of the hybrid CFRCs/biphasic sublayer are characterized using a differential scanning calorimetry (DSC) analysis and a thermal conductivity measurement. The mechanical properties of the hybrid CFRC system are characterized by means of mechanical testing (impact test, tensile test, three-point flexural test, lap-shear adhesion test).The second part of this PhD work investigates the metallization of the hybrid system CFRC/biphasic sublayer using the low-pressure cold spray Dymet 423 system. Copper, aluminum, zinc, and tin powders are used as coating material due to their good electrical and thermal conductivity. Powder mixtures made of these metals and alumina powders (Al2O3) are considered as other potential materials for the cold spray metallization of the biphasic sublayer/CFRC system. An embedment of the cold spray powders onto the biphasic sublayer is found to ease the coating formation, except for the Cu cold spray powder. A continuous 60 μm thick coating of Sn+Al2O3 is obtained onto the biphasic TS-Cu sublayer, that shows the feasibility of surface functionalization of CFRC via a biphasic sublayer and a low-pressure cold spraying.The third part of this PhD work focuses on a phenomenological analysis of the mechanical response of the TS biphasic sublayer during the high-speed collision of the cold spray process. This part aims to depict further improvements through a computational analysis. The erosion issue of the epoxy matrix of the sublayer is found to govern the unsuccessful coating formation onto the thermoset sublayer. Therefore, to find out suitable biphasic polymer materials, a simulation of a Cu powder collision onto thermoplastic media (TP and TP-Cu) has been investigated, that shows a good embedment of the Cu powder onto the TP substrate via a mechanical interlocking (metal-to-resin bonding). The copper particles of the biphasic TP-Cu sublayer enable to promote a plastic deformation of the sprayed Cu particles and is conducive to a bonding formation and coating growth. Finally, to provide a proof of concept, experimental HPCS metallization onto biphasic sublayers made of a TP matrix are performed. A continuous coating formation of spherical Cu, dendritic Cu, and Cu+Al2O3 is obtained onto TP-Cu sublayer, with a thickness of 95 µm, 231 µm, and 114 μm respectively. Thereby, the feasibility of the metallization of CFRC via a TP biphasic sublayer and a high-pressure cold spray deposition has been demonstrated

The purpose is to compare the 2D and 3D analysis methodologies in investigating the performance of a Concrete Faced Rockfill Dam (CFRD) under static and dynamic loading conditions. Ç
okal Dam is the case study which is a CFRD located in northwest Turkey at the Thracian Peninsula. Rockfill interface and faceplate were simulated as nonlinear modulus of elasticity, detailed nonlinear tractive behavior and total strain rotating crack model, respectively. These behaviors were calibrated to define the exact behavior by detailed material tests. The analyses that cannot be done by 2D analyses, such as stress, crack width distribution along the face slab are conducted by 3D analyses to determine the necessity of these outcomes. Since effect of valley ends cannot be produced by 2D analyses, it is necessary to check 3D analyses to ensure liability of the results. Another comparison between detailed analysis of 2D models and linear elastic 2D models were covered to get practical and industrial solutions for the guiding methods of CFRDs for preliminary designs in this study.

The main objective of this thesis was to increase the understanding of interlaminar toughening mechanisms in particle-toughened interlayers within carbon/epoxy laminates. High-resolution Synchrotron Radiation Computed Tomography (SRCT)and Synchrotron Radiation Computed Laminography (SRCL) allowed the crack tip micro-mechanisms to be observed in situ under Mode I and Mode II quasi-static loading conditions. Fracture toughness tests were undertaken to establish the ranking of the ten different material systems, which were compared in terms of the micro-mechanisms observed. Two different intermediate modulus fibres were investigated, with combinations of three different particle types dispersed within the interlayers. The work showed that interlaminar failure in the materials involves a complex process zone, rather than a singular crack tip. Three distinct crack wake bridging mechanisms were identified, namely; fibre-bridging, epoxy-bridging, and particle-bridging ligaments. It was determined that an interlaminar crack path provided a high Mode I and Mode II fracture toughness. The ligament-rich and tortuous crack path appeared to provide higher energy dissipation than the comparably smooth intralaminar failure at the ply interface and associated fibre-bridging mechanisms. Quantitatively, the work showed that a larger number of bridging ligaments in particle containing interlayers correlated to a higher Mode I fracture toughness. Provided that the particles in question could maintain an interlaminar crack path, the particle size and type had a less significant effect on the Mode II toughness. Digital Volume Correlation (DVC) was employed to quantify interlayer strains head of a Mode I crack, showing that the toughening particles can be used as effective markers to enable displacement tracking. A finite element (FE) model was used to explore key variables that were identified experimentally to have an effect on the crack path. The fibre interface strength, particle cohesive strength, density and distribution were shown to affect crack paths. The results implied that the role of the particles is to alleviate the stresses at the ply interface by de-bonding or fracturing internally, following which additional toughness may be generated via the formation of bridging ligaments as failure occurs within the interlayer. Overall, the work is intended to support material development and lead to better predictive capabilities for these materials that are increasingly used in primary aerospace structures.

China’s government invests in hydropower and explicitly in larger dams. An increasing share of such large dams is globally represented by the type Concrete Face Rockfill Dam (CFRD) due to its safe behaviour at a relatively low construction cost. China is however building them higher than has earlier been done and the lack of worldwide experience requires thorough studies on their behaviour. This report presents a study of the Cihaxia dam that is to be built in the river basin of Huang He, regarding the optimisation of an increased rockfill compaction and its final effects on the settlements of the concrete face. The settlements of a typical cross section of the Cihaxia dam are modelled with a Finite Element Method (FEM) program with varying values for a number of structural properties. The effect of each variation indicates what properties that will have the largest effect on the behaviour of the finished structure and points out where focus shall be laid when optimising the design of a high CFRD. The outcome of the FEM analysis shows the static comportment of the rockfill body and its concrete face at two stages, at the end of construction and after reservoir impoundment. The difference between the two provides data on what effects the water load would cause, which constitute the main displacements of the concrete slabs. It is evident from the obtained results that the most important of the studied parameters alongside with the level of compaction is the geometrical extension downwards and inwards of the zone subject to increased compaction. A higher degree of compaction will always produce a beneficial decrease of settlements but might not always be economically legitimate as costs rapidly increase with higher levels of compaction. An adequate level of a CFRD’s compaction increase can with advantage be determined by comparing different designs regarding the volumetric percentage to compact against the calculated decrease in slab deflection.

The damping of perfectly bonded CFRPs may only be increased by increasing the energy dissipation in the matrix. Accordingly the use of short fibres results in a slight increase in loss factor for a negligible sacrifice in stiffness by introducing shear strain magnification at the fibre tips. However, selection of a highly dissipative matrix resin along with the careful design of fibre lay-up yielded a stiff light CFRP with substantially increased damping. An experimental apparatus was designed and built, which enabled the loss factors of CFRPs undergoing both applied and induced combined shear and flexural vibrations to be measured. Predictions of combined mode damping behaviour were made according to existing equivalent strain analyses applied firstly to the CFRP as a macroscopically homogeneous material and secondly to the resin as the dissipating phase of the CFRP. The former produced qualitative agreement with experimental results, although physical considerations suggest this agreement to be coincidental only. The latter analysis was concluded to be more representative although the effects of shear deformation ignored in the model were found to be highly significant. Examination of the effects of high dynamic strain amplitudes on the structural damping of longitudinally restrained members necessitated a revision of the fundamental definition of structural loss factor and the implications of linear material damping. Consequently the basic assumption that for a linearly damped material structural loss factor equals the material loss factor was contradicted. High amplitude strains were found to have negligible effect on resin or CFRP damping, whilst induced axial strains significantly reduced the flexural loss factor. Experimental results endorsed the theoretical models. CFRPs, like resins, displayed essentially linear damping characteristics throughout the investigations. Future analyses of damping should concentrate on energy dissipation in specimens rather than their loss factors.

SEISMIC STRENGTHENING OF A MID-RISE REINFORCED CONCRETE FRAME USING CFRPs: AN APPLICATION FROM REAL LIFE Tan, Mustafa Tü
mer M.S., Department Of Civil Engineering Supervisor: Prof. Dr. Gü
ney Ö
zcebe Co-Supervisor: Assoc. Prof. Dr. BariS Binici May 2009, 162 pages FRP retrofitting allows the utilization of brick infill walls as lateral load resisting elements. This practical retrofit scheme is a strong alternative to strengthen low to mid-rise deficient reinforced concrete (RC) structures in Turkey. The advantages of the FRP applications, to name a few, are the speed of construction and elimination of the need for building evacuation during construction. In this retrofit scheme, infill walls are adopted to the existing frame system by using FRP tension ties anchored the boundary frame using FRP dowels. Results of experiments have previously shown that FRP strengthened infill walls can enhance lateral load carrying capacity and reduce damage by limiting interstory drift deformations. In previous, analytical studies, a detailed mathematical model and a simplified version of the model for compression struts and tension ties was proposed and verified by comparing model estimations with test results. In this study, an existing 9-storey deficient RC building located in Antakya was chosen to design and apply a hybrid strengthening scheme with FRPs and reduced number of shear walls. Linear elastic analysis procedure was utilized (force based assessment technique) along with the rules of Mode Superposition Method for the reftrofit design. FRP retrofit scheme was employed using the simplified model and design was conducted such that life safety performance criterion is satisfied employing elastic spectrum with 10% probability of exceedance in 50 years according to the Turkish Earthquake Code 2007. Further analytical studies are performed by using Modal Pushover and Nonlinear Time-History Analyses. At the end of these nonlinear analyses, performance check is performed according to Turkish Earthquake Code 2007, using the strains resulting from the sum of yield and plastic rotations at demand in the critical sections. CFRP retrofitting works started at October 2008 and finished at December 2008 for the building mentioned in this study. Eccentric reinforced concrete shearwall installation is still being undertaken. All construction business is carried out without evacuation of the building occupants. This project is one of the first examples of its kind in Turkey. Keywords: CFRP, Carbon Fiber Reinforced Polymers, Masonry Infill Walls, Reinforced Concrete Infill Walls, Mid-Rise Deficient Structures, Turkish Earthquake Code 2007, Modal Pushover Analysis, Nonlinear Time History Analysis, Linear Elastic Building Assessment

Isotopes and hydrochemistry were used to define groundwater flow systems and better understand the hydrogeological setting of the Karijini National Park within the Central Pilbara region, this study was initiated because of the near proximity of the Marandoo iron ore mine to the National Park. Based on the stable isotope composition of the water samples, two main groups of water can be identified. Groundwater is characterised by depleted δD and δ¹⁸O, suggesting no significant evaporation effect. Surface water on the other hand is more enriched in δD and δ¹⁸O due to evaporation. The relatively high concentration of Cl- compared to rainfall and depleted δD and δ¹⁸O values of groundwater indicate that recharge of the aquifers is occurring during intense rainfall events when rapid infiltration occurs. Evapotranspiration then acts to concentrate ionic species prior to recharge. The presence of CFCs in the groundwater indicates the presence of modern recharge water. Relationships between various ionic species has shown that infiltration through the Tertiary sequence and subsquent dissolution of carbonate minerals is main influence on increasing concentrations of Ca²⁺ , Mg²⁺ , HCO₃⁻ . The TDS concentration of the groundwater in the Marra-Mamba Iron Formation that hosts the Marandoo ore body is higher than most of the water bodies surrounding the mining area. This suggests that either significant chemical modification is occuring or it is recharged by different mechanisms to that of the Karijini groundwater. Relationships between the major ion concentration and catchment area, surficial Tertiary cover and distance between recharge and discharge were identified. The results show that the hydrochemistry of the water discharging at each location within the National Park can be justified by groundwater evolution within it’s own catchment.

Uma pesquisa de campo foi conduzida para verificar as condições reais de utilização de clorofluorcarbonos em sistemas de refrigeração e de condicionamento de ar. A pesquisa cobriu os setores de refrigeração de supermercados, ar condicionado de edifícios e oficinas de reparação e de manutenção de geladeiras, \"Freezers\" e condicionadores de ar compactos e automotivos. A região escolhida para a pesquisa está localizada no município de São Paulo, tendo uma superfície de 12,504 Km2. As seguintes conclusões principais resultaram deste estudo: Predomina o consumo do HCFC 22 nos usuários pesquisados; a reciclagem e a recuperação ocorrem em pequena escala na região estudada; os sistemas de condicionamento de ar automotivos são a fonte mais significativa de substâncias agressivas à camada de ozônio, nos usuários pesquisados; vazamentos ocorrem por práticas de serviço não adequadas; a utilização do CFC 11 para limpeza de circuitos reduz o ganho obtido em sistemas que empregam o HCFC 22; a manutenção preventiva mostrou ser eficaz tanto para reduzir o consumo de gás refrigerante, como para reduzir a substituição de peças e componentes; a reciclagem e a recuperação do gás refrigerante tem efeito positivo em relação à camada de ozônio, economiza recursos naturais, reduz o consumo de energia, os riscos ao meio ambiente e à saúde da comunidade em geral. Finalmente, são feitas recomendações para o estabelecimento de um programa efetivo de reciclagem e recuperação de gases refrigerantes.
A field study was performed for verifying the actual conditions of the use of chlorofluorcarbons in refrigeration and air conditioning systems. The study has covered the sectors of supermarket refrigeration, building air conditioning systems, and refrigerators freezers and compact and automobile air conditioning systems repair shops. The region chosen for this study is located in the city of Sao Paulo and it has an area of 12.504 km2. The following conclusions resulted from the study: There is a predominance of the of HCFC 22 in the systems surveyied; recycling and recuperation are used in small scale in the region of the study; in the users covered by the study, the automobile air conditioning sector is the most important source of emission of ozone depleting substances; leaks occur because of bad service practices; the use of CFC 11 for circuit cleaning decreases the the gain obtained with the use of HCFC 22; the preventive maintenance has proved to be very efficient both for reducing the consum of refrigeration gases and for reducing the consum of parts and components of the refrigeration system; recycling and recuperation of refrigeration gases have positive effects in relation to the ozone layer, it saves natural resources, and reduces the risk to the enviromnent and to the public health. Finally, recommendations are made for the establishment of an effective refrigerant conservation program.

Tese (doutorado)—Universidade de Brasília, Instituto de Geociências, 2009.
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No estado de Goiás o Sistema Aquífero Guarani – SAG ocupa uma área de 44.000 km2, deste total, 35.138 km2 estão confinados pelos basaltos da Formação Serra Geral, enquanto os 9.580 km2 restantes representam as áreas de afloramentos. Na área de estudos, o sistema aquífero é composto por arenitos eólicos de idade jurássica da Formação Botucatu, sendo o aquífero regional com maior potencial quantitativo. O objetivo principal deste trabalho é a caracterização geoquímica, isotópica e hidrodinâmica do Sistema Aquifero Guarani em sua área de ocorrência no estado de Goiás, Brasil. Informações levantadas em trabalhos de campo realizados nas áreas de afloramento e descrição de perfis de poços tubulares profundos na zona confinada permitiram a elaboração de seções geológicas e colunas estratigráficas. Para a determinação dos parâmetros hidrodinâmicos (condutividade hidráulica K, transmissividade T e coeficiente de armazenamento S) foram utilizados dados de ensaios de bombeamento de 43 poços, dos quais 42 estão localizados na zona não confinada. Os seguintes resultados foram alcançados: nas áreas de afloramento K variando entre 2,3 x 10-4 e 4,8 x 10-4 m/min, T entre 1,7 x 10-2 e 4,7 x 10-2 m2/min e S entre 3,11 a 8,48; na porção confinada o valor de K é de 5,09 x 10-4 m/min, T 5,6 x 10-2 m2/min e S 3,83 x 10-3. Valores da composição de isótopos estáveis de oxigênio e oxigênio das amostras das águas coletadas nos poços são equivalentes a linha meteórica local (δ 2H = 6,5 δ18O + 0,36), indicando que as condições climáticas de quando da recarga não eram diferentes das dos dias atuais e que as trocas isotópicas com o aquífero foram insignificantes. Os valores de δ 13C variam de -5,51 nas porções de alto confinamento, -9,12 nas porções de baixo confinamento e -8,0 nas áreas de afloramento. Idades da água subterrânea na área de recarga, determinadas por concentrações de CFCs, variam entre 12 a 40 anos, onde as idades mais antigas são relacionadas a poços de maior profundidade. Idades da água subterrânea na zona confinada do aquífero, determinadas por 14C, variam entre 680 anos, na região de Lagoa Santa (semiconfinamento), e mais antiga que 40.000 anos, nas regiões de Quirinópolis (alto grau de confinamento) e Cachoeira Dourada (médio grau de confinamento). Medidas in situ e em laboratório foram realizadas para a determinação do pH, ORP, STD, condutividade elétrica e concentração de íons. A água subterrânea é classificada como bicarbonatada cálcica nas áreas de recarga, carbonatada-bicarbonatada cálcica na porção de baixo confinamento, sulfatada-bicarbonata sódica na zona de alto grau de confinamento e sulfatada-cloretada na região de Cachoeira Dourada. Na região de Cachoeira Dourada, a alta concentração de cloreto e sulfato está relacionada à dissolução de minerais evaporíticos como halita e anidrita. No estado de Goiás, o Sistema Aquífero Guarani é caracterizado pela existência de dois sistemas de fluxos regionais de água subterrânea: porção oeste – onde o fluxo subterrâneo está direcionado das áreas de recarga (regiões de Mineiros e Jataí) para o Lineamento do Rio Paraná; porção leste – fluxo subterrâneo direcionado para SW, controlado pelo Lineamento do Rio Paranaíba. Do ponto de vista do modelo conceitual o aquífero pode ser enquadrado como livre, semiconfinado sem contribuição do aquitarde, semiconfinado com contribuição do aquitarde e totalmente confinado. _______________________________________________________________________________ ABSTRACT
In the state of Goiás, Brazil, the Guarany Aquifer System – SAG occupies an area of 44,000 km2, of this, 35,138 km2 is confined by the basalts of the Serra Geral Formation, while the 9,580 km2 remaining represent the outcrops areas. In the research area, the SAG is composed by aeolian sandstone Jurassic age of the Botucatu Formation, and it is considered the most important in terms of regional quantitative potential. The main objective of this work was the geochemistry, isotopic and hydrodynamic characterization of the aquifer. Information from fieldwork in the outcrop areas and the description of deep wells profiles in the confined zone allowed the establishment of stratigraphic columns and geologic sections. For the determination of the hydrodynamic parameters (hydraulic conductivity K, transmissivity T and storage coefficient S) the pumping tests of 43 wells had been used (42 are located in the outcrop zone not). The following results had been reached: in the outcrop areas K between 2,3 x 10-4 and 4,8x 10-4 m/min, T between 1,7 x 10-2 and 4,7 x 10-2 m2/min and S from 3,11 to 8,48; in the confined portion K 5,09 x 10-4 m/min, T 5,6 x 10-2 m2/min and 3,83 x 10-3. Stable hydrogen and oxygen isotopic composition of the water sampled from wells, the values fall close to the local meteoric line (δ 2H = 6,5 δ18O + 0,36), indicating that climatic conditions during recharge were similar the current days and isotopic exchange with aquifer rocks are insignificant. The values of δ 13C change from -5.51 (large confined aquifer) to -9,12 (low confined aquifer) and - 8,0 in the outcrop areas. Ages of groundwater in the recharge area, determined by concentrations of CFCs, change from 12 to 40 years, where the oldest ages are related the deeper wells. Ages of the groundwater of the confined zone, determined by 14C, varied from 680 years, in the Lagoa Santa region (low confined aquifer), and older than 40,000 years, in the Quirinópolis (large confined aquifer) and Cachoeira Dourada regions (medium confined aquifer). In situ and laboratory analysis had been carried out for the determination of pH, ORP, TDS, electric conductivity and ion concentration. The groundwater is classified as bicarbonated calcic in the recharge areas, carbonatedbicarbonated calcic in the low confinement portion, sulfated-bicarbonated sodic in the higher confinement zone, and sulfated-clorated in the Cachoeira Dourada region. In the Cachoeira Dourada region, the higher chloride and sulphate concentration are related to the dissolution of evaporitic minerals as halite and anhydrite. In the state of Goiás, the Guarani Aquifer System is characterized by two regional hydrogeologic systems: west portion - where the groundwater flow is from the recharge areas (regions of Mineiros and Jataí) to the of the River Paraná Lineament and; east portion - where the groundwater flow is southwestward controlled by the Rio Paranaiba Lineament. On the point of view of the conceptual model the aquifer can be fit as unconfined, semi confined without contribution from storage water from the aquitard, semi confined with contribution from the aquitard and fully confined.

O presente trabalho tem como objetivo investigar os processos de ascensão e queda dos clorofluorocarbonetos (CFCs) como bens de consumo, bem como o desenvolvimento da percepção de risco da comunidade química em relação a esses compostos, que culminou com sua caracterização como agentes de risco ambiental global. Para isso, foi desenvolvido um estudo de caso histórico acerca do uso dos CFCs ao longo do século XX, de solução tecnológica ideal a protagonista de uma inédita dimensão de risco químico. Além disso, foi realizada uma análise de cartas enviadas por leitores, editoriais e resenhas de livros publicadas em cinco periódicos científicos: Chemical & Engineering News, Journal of Chemical Education, Environmental Science and Technology, Nature e Science, no período compreendido entre 1975 e 1991, e de livros didáticos de Química Ambiental publicados entre 1970 e 1995 - período marcado por intenso debate sobre a possibilidade de destruição da camada de ozônio estratosférica. A escolha desses periódicos e livros buscou contemplar diferentes seções da comunidade química, de modo a se ter uma amostra representativa de diferentes formas de pensamento dentro desse amplo espectro profissional que constitui a química. Para análise dessa amostra foi escolhida a Teoria Cultural de Douglas e Wildavsky, a qual descreve quatro visões de mundo que se mostram bastante adequadas para analisar as percepções de risco, as atitudes e os argumentos envolvidos nas discussões da época. Os resultados obtidos apontam para mudanças nas percepções de risco da comunidade química, aproximando-as do Princípio da Precaução para a tomada de decisões, em um período marcado pelo desenvolvimento da Química Ambiental.
This study aims to investigate the processes of rise and fall of chlorofluorocarbons (CFCs) as consumer goods, as well as the development of risk perception regarding these compounds among the chemists community, culminating in its characterization as agents of global environmental risk. A historical case study on the trajectory of CFCs throughout the twentieth century, from ideal technological solution to protagonist of an unprecedented scale chemical risk, was developed. In addition, the study includes an analysis of letters from readers, editorials and book reviews published in five journals: Chemical & Engineering News, Journal of Chemical Education, Environmental Science and Technology, Nature and Science, in the period between 1975 and 1991, and also an analysis of Environmental Chemistry textbooks published between 1970 and 1995 - a period marked by intense debate about the possibility of destruction of the stratospheric ozone layer. The choice of these journals and books sought to include different sections of the chemistry community, in order to get a representative sample of different ways of thinking within the broad professional spectrum of chemistry. Douglas\' and Wildavsky\'s Cultural Theory was selected to analyse this sample. The theory describes four worldviews that seems rather appropriate to analyze risk perceptions, attitudes and arguments involved in the discussions of the time. Results point to changes in chemists\' risk perceptions, which brought them closer to the Precautionary Principle as a guide to decision making in a period marked by the development of Environmental Chemistry.

I compositi laminati, specialmente i Carbon Fiber Reinforced Polymers (CFRPs), possiedono ottime proprietà meccaniche ed un peso contenuto rispetto i materiali metallici. Uno dei problemi più importanti che i laminati presentano è il cedimento per delaminazione, ovvero il distaccamento delle lamine che costituiscono il composito, in seguito a sollecitazioni esterne e/o alla presenza di difetti formati durante il processo di lavorazione. Per poter minimizzare tale fenomeno sono stati studiati vari metodi; fra questi vi è l’utilizzo di tessuti nanofibrosi che, intercalati fra le lamine, riescono ad ostacolare efficacemente la propagazione della cricca. Nel presente lavoro di tesi sono stati prodotti, mediante elettrofilatura, tessuti nanofibrosi polimerici additivati con grafene, da impiegare per la modifica strutturale di compositi laminati. In particolare, è stata svolta l’ottimizzazione delle soluzioni (concentrazione polimero, sistema solvente) e dei parametri di processo (potenziale, portata, distanza ago-collettore) per diversi materiali polimerici. Per effettuare un’efficiente dispersione del grafene sono stati effettuati vari cicli di sonicazione. Le membrane sono state caratterizzate morfologicamente mediante microscopia elettronica (SEM) e termicamente mediante calorimetria differenziale a scansione (DSC). Infine, sono stati prodotti tessuti di grandi dimensioni adatti ad essere integrati, prossimamente, in compositi laminati per verificarne l’efficacia contro la delaminazione.

Orientador: Mary Luci de Souza Queiroz
Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Ciências Médicas
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Resumo: Neste trabalho, investigamos os efeitos da exposição ao chumbo sobre o crescimento e diferenciação de células hematopoiéticas, as chamadas células formadoras de colônias (CFCs) da medula óssea de animais infectados e tratados com chumbo. Estudamos também os efeitos da exposição ao metal sobre a atividade dos fatores de crescimento de colônias (CSFs) no soro, assim como a sobrevida deste animais após infecção. Para a realização dos experimentos através da técnica de cultura clonal, em meio semi-sólido, os animais foram infectados com a bactéria Listeria monocytogenes após final do tratamento com acetato de chumbo. Após infecção com esta bactéria ocorre um aumento no número de células formadoras de colônias (CFCs) no baço, assim como nos níveis séricos de fatores estimuladores de colônias (CSFs). Utilizamos duas linhagens de camundongos: Balb\cj, susceptível a Listeria monocytogenes, e C57BI10 resistente a esta infecção. As doses de acetato de chumbo utilizadas foram: 1300, 130 e 13 ppm por períodos de 70, 30 e 10 dias. Ao final do tratamento os animais foram inoculados com doses de 3x102 - Balb\cj e 3x106 - C57BI10 e sacrificados 24, 48 e 72 horas após inoculação. A sobrevida destes animais foi determinada após observação destes camundongos por um período de 10 dias. Nossos resultados demonstraram que o efeito supressor do chumbo foi evidente em ambas linhagens. Na linhagem susceptível à infecção os efeitos da exposição ao chumbo ficou evidente em todos os grupos expostos, infectados ou não, nos três intervalos de tempo estudados após infecção. Nos animais resistentes a esta infecção o efeito supressor do acetato de chumbo também ficou evidente. Nesta linhagem, nas primeiras 24 horas após infecção tanto o chumbo como a infecção apresentaram efeitos supressores. Entretanto após 48 horas o efeito supressor da infecção foi superado, permanecendo apenas o efeito supressor induzido pelo chumbo. Não observamos alterações na atividade dos fatores estimuladores de colônias no soro dos animais em decorrência da administração do chumbo, sugerindo que este metal atue através de ação direta sobre os precursores hematopoiéticos. Observamos também um aumento na mortalidade em animais infectados com doses sub-Ietais de Listeria monocytogenes em ambas linhagens estudadas, quando expostas ao metal
Abstract: In this work we have investigated the effects of lead exposure on the growth and differentiation of hematopoietic cells from bone marrow, the so called colony forming cells (CFCs), in normal and infected mice. We also studied the effects of this exposure the serum activity of hemopoietic colony stimulating factors (CSFs), as well as, the survival of these mice after the infection. For this purpose, we used the technique for the clonal culture of hemopoietic cells in semi-solid medium. Mice were infected with the bacteria Listeria monocytogenes after treatment with lead acetate. Two strains of mice were used: Balb\cj (susceptible to Listeria monocytogenes) and C57BI10 (resistent to this bacteria). The doses of lead acetate were: 1300, 130 and 13ppm in periods of 70, 30 and 10 days. At end of this treatment, mice were infected and killed 24, 48 and 72 hours after the inoculation of the bacteria. The survival of these mice was determineted after a period of ten days. The suppressives effects of lead were observed in both strains in the three different periods studied. The dose-response relationship was observed with the 3 doses of lead used in relation to the effects of the infection, however, we observed that in the resistant strain the suppressives effects were overcome 48 hours after the administration of the baçteria. In the susceptible strain the suppressives effects of the infection were evident in the 3 periods studied. No changes were observed in the serum activity of CSFs due to the administration of lead, thus suggesting that this metal acts by a direct action on the myelopoietic cells. A significant decrease in host resistence, as measured by the mortality rate, was found when both strain of mice, after treatment with 1300ppm of lead for 30 days, were challenged with sub-lethal doses of Listeria monocytogenes
Mestrado
Mestre em Ciências Médicas

I Sverige kan VKR (varmformade konstruktionsrör) vara 15-23 % dyrare än KKR (kallformade konstruktions­rör) av samma tvärsnittsstorlek. Trots detta lägre pris på KKR har det upp­skattats att i Svensk stål­byggnation används endast 5 % KKR, av det totala användandet av VKR och KKR. I detta examensarbete har det först undersökts vilka skillnader i egenskaper som finns mellan VKR och KKR. Därefter beräknas prisdifferensen mellan de två profiltyperna när de utsätts för en centrisk tryckkraft under likadana förhållanden. Målet är att ta reda på vilket som är det mest ekonomiskt lönsamma alternativet i valet mellan VKR och KKR. Tryckkraftskapaciteten med hänsyn till knäckning för alla profilstorlekar i Tibnor konstruktions­tabeller har beräknats för varje möjlig kombination av tio olika längder mellan 1 till 10 m, tio olika laster mellan 100 till 1000 kN och två olika upplagsförhållanden, ledad i båda ändarna eller fast inspänd i båda ändarna. De KKR‑ respektive VKR-profiler med lägst pris, som håller för lasten, har jämförts och prisdifferensen mellan dessa redovisas genom att ange hur många procent dyrare, eller billigare, VKR är i jämförelse med KKR. I 80 % av mätningarna vid ledad infästning i båda ändarna blev KKR det mest ekonomiskt lönsamma alternativet. Samma siffra blev 86 % för fast inspänd i båda ändarna. Den genomsnittliga pris­differensen hamnade på 10-11 % med ett spridningsmått på 8-12 %. Detta leder till slutsatsen att ett användande av enbart KKR kan resultera i be­sparingar på ca 10‑11 % i stålkostnader, jämfört med att enbart använda VKR. Utifrån pris­differensernas variation dras därefter slutsatsen att det inte finns några tendenser på att VKR eller KKR är mer lönsam än den andra inom något specifikt längd- eller lastintervall. Rekommendationen är att i första hand optimera och använda den profiltyp som är mest lönsam för rådande förhållanden. Om en optimering inte är möjlig blir istället rekommendationen att använda KKR.
In Sweden, hot formed rectangular hollow sections (HFRHS) can be 15-23 % more expensive than cold formed rectangular hollow sections (CFRHS) of the same section size. Although the price on CFRHS is lower, estimations reveals that   - from the total use of HFRHS and CFRHS in Swedish steel buildings - CFRHS is only utilized by less than 5 % compared to 95 % HFRHS. This study began by examining the differences between these two types of steel. The price difference between the two processed metal types was then calculated when both of them were subjected to a centric compressive force under the same conditions. The purpose was to compare prices and find out which one is the most economically feasible, offering a more profitable choice between HFRHS or CFRHS. The design buckling resistance of all the section sizes in Tibnor kon­­struktions­tabeller was calculated for every possible combination out of ten different lengths between 1 m and 10 m, ten different loadings between 100 kN and 1000 kN and two different support conditions being pinned at both ends and fixed at both ends. The sections sizes of CFRHS and HFRHS that withstood the loading and held the lowest prices were compared by calculating the price difference as per­centage increment or decrement between the two types of hollow sections. In 80 % of the cases, when pinned at both ends, CFRHS showed to be the most economically feasible alternative. When fixed at both ends the same number was 86 %. The average price difference was 10-11 %, showing an absolute deviation of approximately 8‑12 %. These findings conclude that using only CFRHS can result in savings of 10‑11 % from reduced costs of steel, compared to only using HFRHS. From the observed variation of the price differences another conclusion is drawn that there aren’t any tendencies showing HFRHS or CFRHS to be more economically feasible than the other in a specific interval of length or loading. The recommendation is to optimize and use the type of steel that is the most economically feasible under the current circumstances. If an optimization isn’t possible then the recommendation is to use CFRHS.

The cost of manufacturing high quality composite components can be significantly reduced by using Out of Autoclave (OOA) processes if they can achieve final parts with a finish quality as high as that obtained using an autoclave process. Much research has been carried out recognising that regardless of the reinforcement fibre orientation, manufacturing of preimpregnated (prepregs) carbon components is much affected during its forming stage by fibre deformation and failure modes. This work sought to reduce wrinkling in the moulding of prepregs by introducing slip layers within the lay-up. Three types of slip layers were used: a dry fabric, a resin rich layer and a resin film. In order for the slip layers to be fully incorporated into the final laminate the resin content within the slip layer must be adjusted prior to crosslinking. In the case of dry fabric layer, additional resin must be introduced and in the case of a resin rich layer and resin film layer, excess resin has to be removed. The laminates used in the project were based on 2/2 twill and unidirectional carbon prepregs. These were manufactured by either Resin Infusion (RI) or Vacuum Bagging (VB). Resin adjustments were made at the same time. The 2/2 twill and unidirectional carbon prepregs were first characterised by Differential Scanning Calorimetry (DSC) and Dynamic Mechanical Thermal Analysis (DMTA) before RI and VB. Dry 2/2 twill and unidirectional carbon fabrics and/or Resin Film (for VB) or fabrics and Epoxy Resin (for RI) were introduced in several plybooks and then cured. Final parts were either made of 2/2 twill carbon or unidirectional carbon. The parts were used to investigate the relationship between individual plies during the consolidation of a plybook. The first characterisations were done on flat laminates. Also two moulds were manufactured and used to produce new parts for further characterisations. The first, an aluminium mould was machined using a Computer Numerical Control (CNC). The second mould was a fan blade, made using chopped strand mats. The final parts had 3, 4 or 6 plies. These parts were characterised using Optical Microscopy (OM), Scanning Electron Microscopy (SEM), and Torsion testing. The results provide a first step towards understanding how the friction at a ply/ply level can be influenced by the "starving" or the "enriching" of resin in a plybook during its consolidation. The work showed that in OOA manufacturing, the friction at a ply/ply level can be controlled by introducing Resin Film, Dry or Resin Rich Fabrics in a prepreg plybook. It was demonstrated that introducing lubrication to control ply friction during forming can result in quality part as high as that obtained from a traditional composite forming process. As the final parts were made using a fixed die mould and a vacuum bag, most of the plies in the layups could deform individually and accommodate interply shear. Torsion testing on a number of a random selection of samples showed negligible effects on shear stresses, strengths and modulus within the parts were negligible. It is argued that the flexibility of the vacuum bag could have had an impact on the layups during forming. The plies could conform to the mould easier. This work has potential for other applications. For example in match die moulding, introducing wet lubrication could improve interply shear during forming and help in improving accuracy and geometrical conformity of final parts. Furthermore, developing techniques to control friction during forming in OOA can be attractive to industries which could not afford to invest in this OOA prepreg technology. OOA processing times have become very attractive to industries such as the sporting good, automotive, wind energy and transportation. These industries could explore the opportunity presented by the work in this EngD thesis.

Orientador: Newton Muller Pereira
Tese (doutorado) - Universidade Estadual de Campinas, Instituto de Geociencias
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Doutorado

Esta pesquisa teve por objetivo identificar como ocorre o processo decisório nas Casas Familiares Rurais dos municípios de Manfrinópolis e Pato Branco, localizadas na região sudoeste do Paraná. Para isso foram realizadas algumas pesquisas, dentre elas a bibliográfica, a documental e a exploratória. A pesquisa bibliográfica foi realizada através da leitura de livros, artigos, dissertações e teses acerca do tema gestão participativa; materiais sobre a constituição das Casas Familiares Rurais, bem como o contexto da Pedagogia da Alternância, que é fundamental para este estudo. Já a pesquisa documental verificou os documentos que regem a atuação das Casas Familiares Rurais, ou seja, o Estatuto da Associação de cada CFR; também foi pesquisado o Estatuto da Associação Regional nas Casas Familiares Rurais do Sul do Brasil – ARCAFAR SUL. A pesquisa exploratória se realizou através de uma coleta de dados, a qual se deu da seguinte forma: roteiro de entrevista semiestruturado com os coordenadores das CFR`s, membros da Associação das CFR`s. Presidente, Assessora Pedagógica e Articuladora de Projetos da ARCAFAR SUL. Para o tratamento dos dados nos documentos foi verificada a existência do termo gestão participativa e a forma de constituição e do papel de cada membro da Associação das CFR`s. O estudo foi realizado em três etapas. Na primeira foi realizada a construção do cenário da pesquisa, ou seja, se contextualizou a região sudoeste do Paraná e os municípios de Manfrinópolis e Pato Branco. A segunda parte é constituída por um referencial bibliográfico sobre gestão participativa e traz ainda a constituição histórica das CFR`s, seu surgimento na França, no Brasil e na região sul do Brasil. A terceira parte contém os resultados referentes à coleta de dados realizada. Os resultados obtidos na pesquisa evidenciaram a dificuldade financeira que as CFR`s enfrentam, tendo em vista que estas precisam firmar parcerias com órgãos públicos, ONGs ou empresas privadas. Estas dificuldades financeiras acabam implicando em outros fatores pedagógicos como, por exemplo, falta de estrutura adequada das CFR`s. Todavia, a pesquisa apresentou também alguns dados interessantes, tais como: melhora do desempenho e comportamento dos jovens em relação à escola tradicional frequentada anteriormente por eles. Ainda, segundo os pesquisados, a CFR ajuda a manter o jovem no campo com um Projeto Profissional de Vida, tendo em vista que é necessário sim incentivar que estes permaneçam no meio rural, mas que estes tenham condições de aumentar ainda sua renda.
This research aimed to identify the decision making process as it occurs in the Rural Family Houses in Manfrinópolis and Pato Branco municipalities, located in southwest region of Paraná. Some surveys were carried out, among them bibliography, documentary and exploratory. The bibliography search was performed by reading books, articles, thesis and dissertations on the participative management subject; materials on the constitution of Rural Family Houses, as well as the context of the Pedagogy of Alternation, which is crucial for this study. The document research verified documents governing the operation of Rural Family Houses, in other words, the Statute of Association of each RFH, it was also researched the Regional Rural Family Houses Association Statute in Southern Brazil. The Exploratory research was through a data collecting, which occured as follows: semi-structured interview guide with the RFHs coordinators, members of the Association of RFHs. President and the Regional Rural Family Houses Association in Southern Brazil Educational Adviser and Project organizer. For the processing of the documents was verified the existence of the term and form of participative management constitution and the role of each member of the Association of CFRs. The study was conducted in three stages. The first was held at the construction stage of the research, in other words, contextualized to the southwest region of Paraná and the municipalities of Manfrinópolis and Pato Branco. The second part consists of a referential literature on participative management and also brings the historical constitution of RFHs, its appearance in France, Brazil and southern Brazil. The third part contains the results concerning to the data collection done. The results obtained in the research highlighted the financial difficulties that the RFHs face, considering that they need help from government agencies, NGOs or private companies. These financial constraints end up involving other pedagogical factors such as, for example, lack of adequate structure of the RFHs. But the survey also showed some interesting data, such as improved performance and behavior of young people in relation to traditional school previously attended by those young people. Also according to those surveyed RFH helps keep the young in the field with a Professional Life Project, considering that it is necessary to encourage them to remain in rural areas, but they are still able to increase their income.

Communication difficulties are common in individuals with different types of disabilities. Hence, many may need Augmentative and Alternative Communication (AAC) to be able to communicate. Communication is the foundation of all social relations and studies report that insufficient communication can lead to reduced quality of life and be a predictor for behavioral problems. Even though communication is important there are indications that many individuals with communication difficulties do not get the support they need. People in the individuals’ network, such as family and personnel, play an important role in identifying these individuals, but to date there is no simple tool for that purpose. The aim of this pilot study was therefore to investigate if the Communication Function Classification System (CFCS) could be used to classify the communicative ability in adults attending a day center. Individuals attending day centers usually have disabilities that involve communication difficulties. The participants (n = 9) were family members (n = 3), personnel at day centers (n = 5) and speech-language pathologist (n = 1). The participants classified the communicative abilities of two individuals using CFCS. Two statistical measures, average deviation and percent agreement, were used to calculate the inter-rater reliability. The total average deviation was 0,2 and the total percent agreement was 65 %, which indicate that CFCS can be used to classify the communicative ability in adults attending a day center. However, the participants addressed some critique toward CFCS, therefore future studies should consider using another tool for identifying communication difficulties.
Kommunikativa svårigheter är vanligt hos individer med olika typer av funktionsnedsättningar. Många av dessa behöver därför ett Alternativt och Kompletterande Kommunikationssätt (AKK) för att kunna kommunicera. Kommunikation är grunden för all social gemenskap och forskare har rapporterat att bristande kommunikation kan leda till sämre livskvalitet samt vara en riskfaktor för olika typer av problembeteenden. Trots att kommunikation är viktigt finns indikationer på att många individer med kommunikativa svårigheter inte får det stöd de behöver. Omgivningen i form av till exempel personal och närstående spelar en viktig roll i identifieringen av dessa individer, men det saknas ett enkelt verktyg för dem att använda i det syftet. Föreliggande studie syftade därför till att, i en pilotstudie, undersöka om klassifikationssystemet Communication Function Classification System (CFCS) kan användas för att skatta den kommunikativa förmågan hos vuxna brukare med insatsen daglig verksamhet. De som får insatsen daglig verksamhet har funktionsnedsättningar som ofta innefattar kommunikativa svårigheter. Deltagarna (n = 9) i studien var närstående till två brukare, daglig verksamhetspersonal, och en logoped. Deltagarna i studien skattade brukarnas kommunikativa förmåga utifrån CFCS. Två statistiska mått, genomsnittlig avvikelse och procentuell överensstämmelse, användes för att beräkna interbedömarreliabiliteten för deltagarnas skattningar. Den totala genomsnittliga avvikelsen var 0,2 och den totala procentuella överensstämmelsen var 65 %. Det begränsade underlaget gör slutsatserna osäkra, men resultaten tyder ändå på relativt god samstämmighet mellan deltagarna, och att CFCS skulle kunna användas för att skatta den kommunikativa förmågan hos vuxna brukare med insatsen daglig verksamhet. Deltagarna riktade dock viss kritik mot CFCS, vilket gör att fortsatta studier bör överväga att använda ett annat verktyg för identifiering av kommunikativa svårigheter.

Les traceurs transitoires tritium-helium3 et cfcs sont utilises pour la validation du modele de circulation generale oceanique global opa (lodyc). Ces traceurs anthropiques sont particulierement adaptes pour valider des processus de ventilation d'echelle de temps de quelques decennies, tels que la ventilation de la thermocline et la formation des eaux profondes et intermediaires. La validation du modele et l'analyse des simulations est realisee par comparaison avec des mesures obtenues lors de campagnes oceanographiques (geosecs, tto, ajax). Les simulations ont permis de tester la nouvelle parametrisation du melange vertical (tke) basee sur une equation d'evolution de l'energie cinetique turbulente, dont le principal avantage consiste a reproduire une couche melangee a la surface de l'ocean. La validation avec les traceurs transitoires anthropiques a permis de mettre en evidence le role essentiel de cette couche de melange et de son cycle saisonnier sur les processus de ventilation de l'ocean. La couche de melange a pour effet de renforcer l'injection et la subduction des traceurs dans la thermocline, et les simulations ont montre l'importance du cycle saisonnier et de la subduction hivernale dans le modele.

Le travail de thèse porte sur la caractérisation géochimique et la détermination des temps de résidence des eaux circulant dans la partie profonde du substratum du bassin versant du Strengbach. Le travail s’appuie sur l’étude comparée des variations chimiques, isotopiques (87Sr/86Sr, 143Nd/144Nd et (234U/238U)) et des geochronomètres des eaux (CFC-SF6, 14C, 4He) d’échantillons de sources, de piézomètres (15 m de profondeur) et de forages profonds. Les résultats mettent en évidence deux types d’eaux, avec des eaux peu chargées en surface (eaux de sources et de piézomètres) et des eaux plus chargées en profondeur, au regard des principales fractures. L’origine de ces différences a été discutée en termes de variation des temps de résidence et d’un point de vue des interactions eaux-roches. Cette étude a montré qu’un facteur important expliquant ces différences est le temps de résidence des eaux, avec des eaux récentes dans le système superficiel et des eaux anciennes (sup. à 1000 ans) dans le système profond. L’analyse isotopique a montré que les signatures Sr-Nd des différentes masses d’eaux peuvent, au premier ordre, s’expliquer par la dissolution des pôles phosphates-plagioclase-biotite classiquement utilisés sur le bassin. La variation entre les différentes eaux profondes suggère des interactions avec des minéraux secondaires spécifiques pour chacune des eaux
The PhD thesis concerns the geochemical characterization and the determination of the residence times of the water circulating in the deep part of the substratum of the Strengbach catchment. The work is based on the comparative study of chemical, isotopic variations (87Sr/86Sr, 143Nd/144Nd and (234U/238U)) and water geochronometers (CFC-SF6, 14C, 4He) of samples from spring, piezometers (15 m deep) and deep boreholes.The results highlight two types of water, with lower cationic loads for surface waters (spring and piezometer water) than deep water, sampled in front of the main fractures. The origin of these differences has been discussed in terms of variation in residence times and from a point of view of water-rock interactions. This study has shown that an important factor explaining these differences is the residence time of waters, with recent waters in the surface system and old waters (more than 1000 years) in the deep system. The isotopic analysis has shown that the Sr-Nd signatures of the different water can, at first order, be explained by the dissolution of the phosphate-plagioclase-biotite end-members conventionally used on the catchment. The variation between the different deep waters suggests interactions with specific secondary minerals for each of the waters

Le détourage est la première opération d’usinage après la fabrication et le démoulage des structures composites. Cette opération, qui est généralement effectuée avec un procédé conventionnel d’enlèvement de matière à l’aide d’un outil de coupe, conduit à l'apparition de plusieurs types d’endommagements qui sont suivi par la génération de particules nocives lors d’un usinage sans lubrification. Ces particules, générées lors de l'usinage à sec de composites constituent une menace sanitaire, car elles peuvent rester en suspension dans l'air et s'infiltrer dans le corps de l'opérateur, représentant un risque de danger respiratoire. Malheureusement, la compréhension des phénomènes d’émission de particules lors de l'usinage du composite est actuellement insuffisante. De plus, l’apparition de dommages localisés sur la surface usinée (due à l’interaction entre l’outil et le composite) peut réduire la tenue de la structure en service du fait de la formation de zones de concentration de contraintes. En conséquence, il est nécessaire de mieux comprendre les causes sous-jacentes de la création de dommages, ainsi que la relation entre les dommages induits par l'usinage et le comportement mécanique. Il est important de noter que d’un point de vue industriel le critère de rugosité de surface est largement utilisé pour quantifier la qualité d’usinage de la surface composite ainsi engendrée ; cependant la relation entre ces deux critères reste complexe. Ainsi, afin de répondre à cette problématique, ce travail de thèse s’est concentré sur trois objectifs principaux. Tout d'abord, des études ont été menées sur l'usinabilité d'échantillons de stratifiés composites multidirectionnels à base de résine époxy et de fibres de carbone lors du détourage à l'aide d'outils de coupe en PCD (diamant polycristallin). Plus précisément, l’influence des paramètres de coupe (vitesse d’avance et vitesse de coupe) et de la distance de coupe (usure de l’outil) ont été étudiés afin de voir leur influence sur les efforts de coupe et sur la température d’usinage induite, puis une caractérisation multi-échelle des dommages induits par l’usinage a été menée. Cette caractérisation multi-échelles des dommages induits par l’usinage a consisté à l’observation post-mortem des échantillons usinés à l’aide de différentes techniques telles que la tomographie à rayons X, la microscopie confocale et le MEB. Grâce à cette caractérisation multi-échelles, la qualité d’usinage a été quantifiée à l’aide de nouveaux paramètres tels que le volume de cratères, Cv, basé sur la quantification des défauts de cratères et la profondeur des dommages, D, mesurés à l’aide d’observations tomographiques à rayons X. Le deuxième objectif de cette thèse était centré sur l'influence des paramètres de coupe (vitesse de coupe, vitesse d'avance et profondeur de coupe radiale), la distance de coupe et la géométrie de l'outil sur le nombre de particules nocives générées lors de la coupe. Les résultats de cette étude sur les émissions de poussières pourront être très utiles à la communauté industrielle pour choisir les bonnes conditions d’usinage afin de protéger les opérateurs susceptibles d’inhaler les particules présentes dans l’air dans la zone d’usinage. Les résultats obtenus ont clairement montré que pour réduire les émissions de particules nocives, il était nécessaire d’augmenter la profondeur de coupe radiale ou la vitesse d’avance. Néanmoins cette combinaison de conditions de coupe conduit en général à une mauvaise qualité d'usinage
Trimming is the first operation of machining after the manufacturing and demolding of the composite structures. This operation which is usually conducted with conventional process of material removal (by cutting tool) induces various forms of damage which is accompanied by the generation of harmful particles in case of dry machining. In fact, particles generated during dry machining of composite pose a dangerous threat, as they can get suspended in the air and infiltrate inside body of operators giving rise to risk of respiratory hazard. Unfortunately, the understanding of particulate emission during machining of composite is presently incomplete. In addition, the appearance of damages located on the machined surface (due the interaction tool/plies) can reduce the structural performance in service due to the formation of stress concentration zones. As a result, it is necessary to understand the underlying causes for generation of damage, and also the relationship between machining induced damage and mechanical behavior. It is important to notice that, industrially, surface roughness criterion is widely used to quantify the machined quality of the newly generated composite surface. However, so far this has been ambiguous approach. Hence, to address the problems mentioned, this thesis focuses on three main objectives. Firstly, studies on the machinability of multi-directional specimens made of carbon fiber reinforced plastics laminates (CFRPs) during trimming with PCD (Polycrystalline Diamond) cutting tools. Specifically, the influence of cutting parameters (feed speed and cutting speed), cutting distance (tool wear) on the cutting forces, machining temperature induced as well as the multi-scale characterization of the machining induced damages have been investigated. For the multi-scale characterization of the induced machining postmortem observations of the machined specimens, using different techniques such as X-ray tomography, confocal microscopy and SEM, are used. Thanks to this multi-scale characterization, the machining quality was quantified using newly proposed parameters such as crater volume ‘CV’ based on the quantification of the crater defects and maximum depth of damage (D) based on the X-ray tomography. The second objective of this thesis was focused on influence of cutting parameters (cutting speed, feed speed, and radial depth of cut), cutting distance, and tool geometry on the number of harmful particles generated during trimming. The outcome of this study on the dust emission can be beneficial for the industrial community to select the safe machining condition for protecting the operators who potentially inhale the particles in the air in the machining area. The obtained results clearly highlighted that to reduce the emission of the harmful particles it is necessary to increase the radial depth of cut or the feed rate. However, this combination of cutting conditions, leads to poor machining quality. This inspired to propose a new design of cutting tool geometry in collaboration with ASAHI Company

碩士
國立成功大學
環境工程學系
86
It has been realized that chlorofluorocarbons (CFCs) diffused into the stratosphere and broke down the ozone layer. There is also a direct correlation between the increasing concentrations of CFCs in the atmosphereand the green house effect. Although CFCs as solvents and detergents havebeen highly restricted and replaced by hydrochlorofluorocarbons (HCFCs), CFCsstill exist in the forms of refrigerants, heat- transfer media, propellants and various solvents in the electronic industry. Chlorofluorocarbons are among the mostinert substances known. Many methods, such as incineration, catalyticdecomposition and reaction with molten sodium, have been used tocollect and dispose of the remaining stocks of CFCs. These methods were reported to havetechnical or economical difficulties. Carbtree very attractivefor complete mineralization of CFCs in a noncorrosive operating condition. Thus,the main objective of the present work was to investigate the feasibilityfor destroying CFCs with metal oxalate. Experimentally in a single pass through the sodium oxalates bed at 290 Ccaused a nearly complete mineralization of CFC-12, HCFC-141b,HFC-134a and CCl4in 5 minute after mineralization. Water vapor in the feed stream may maintain a high mineralization activity in an extended reaction cycle. It is evident by XRD and SS-NMR that the mineralized surface of sodium oxalate have a 40~80A layerof NaCl species. The activation energy (31.4 Kcal/mol) and preexponential constant (lnA=33.1 hr-1) of the pyrolysis of PU/CFCs wastes were obtained. At least three discretefeatures at 328,423, and 443K are observed corresponding to desorption of HCFC-141b from external internal, and crosslink of the PU matrix, respectively.It indicates that pyrolysis of the PU polymer (at elevated temperature ) may notbe effected by the presence of HCFCs. keywords : chlorofluorocarbons, pyrolysis, mineralization, sodium oxalate.

Fiber reinforced plastic (FRP) structures are widely used compared to metallic structures due to their superior mechanical properties and lightweight. However, anisotropy and heterogeneity inherent to FRPs cause a multitude of damage mechanisms during the life of these structures. Often, residual stresses generated in FRP structures due to mismatch in thermal properties of the constituents are not accounted for in the design phase. These cure residual stresses have known to be quite detrimental to the performance of the composite structures resulting in loss of functionality (distortions) or load-carrying capability. The present study, investigates process induced cure residual strain (CRS) development in carbon fiber reinforced plastic (CFRP) laminates composed of different layup sequences and thicknesses. In addition, CRS development due to internal temperature gradient due to exothermic polymerization reaction within the laminate has been characterized A comprehensive experimental test methodology is developed to measure the in-situ CRS in CFRP laminates prepared by wet layup technique. To delineate the effect of anisotropy and heterogeneity exhibited by CFRPs on CRS development, detailed experimental plan of measuring in-situ CRS in pristine epoxy, unidirectional (UD)-CFRPs and multidirectional (MD)-CFRPs has been established and CRS measured. Emphasis is laid upon quantifying the variation in CRS magnitudes as a function of laminates lay-up sequence and thickness. Calibration of fiber Bragg grating (FBG) sensors are carried out by following well established procedures. Open hole tensile (OHT) tests are also conducted to correlate in-situ strains with measured surface strains using digital image correlation (DIC). Results indicate process induced CRS measured are significant that may result in laminate deformation and micro stresses causing matrix micro-cracking during curing. ii

Multiwalled carbon nanotubes (MWCNTs) were purified to ultra high purity levels (99.9%) by high temperature (26000C) heat treatment method. It was observed that, the structural perfection of MWCNTs increased besides improvement in their purity. Based on the TGA, XRD, TEM and Raman spectroscopy studies mechanisms are proposed for the observed structural changes to MWCNTs. These mechanisms says that, during high temperature treatment, the innermost walls of the MWCNTs collapse due to thermal stresses. However, it was observed that, as long as some traces of the metallic impurities are present, they suppress the collapse of the internal walls. Once the metallic impurities are removed, structural distortion of MWCNTs takes place. It was observed that heat treatment for 60 mins is optimum to obtain highly pure and structurally perfect MWCNTs. These purified MWCNTs were subsequently amino functionalised. FT-IR and XPS methods were used to ascertain the functional groups present on the MWCNTs.

As próteses totais implanto-suportadas com estrutura em compósito reforçado com fibra de carbono (na língua inglesa, Carbon Fiber Reinforced Composite - CFRC) parecem ser uma alternativa viável para reabilitar pacientes com arcadas edêntulas. Atualmente, os estudos existentes estão focados em próteses instaladas na maxila. As pesquisas iniciais tinham como objetivo buscar um reforço eficiente para as estruturas de próteses totais removíveis (PTR), na década de 70. Com o desenvolvimento de novas resinas e novas fibras, os problemas apresentados pelos acrilatos sofreram grande redução. O único estudo coorte foi publicado em 2017 confere às próteses implanto-suportadas com CFRC bons resultados quanto à rigidez, resistência, biocompatibilidade, peso, estética e foi constado uma menor perda do osso marginal em torno dos implantes que recebem carga imediata, a obter assim, melhor performance que as tradicionais próteses totais implanto-suportadas com estrutura metálica.
The implant-supported full dentures with carbon fiber reinforced composite structure (CFRC) appear to be a viable alternative to rehabilitate patients with edentulous arches. Currently, the existing studies are focused on prostheses installed in the maxilla. The initial research was aimed at finding an efficient reinforcement for the structures of removable dentures (PTR) in the 70's. With the development of new resins and new fibers, the problems presented by the acrylates suffered a great reduction. The only cohort study was published in 2017 that gives CRFC implant-supported dentures good results in terms of stiffness, strength, biocompatibility, weight, aesthetics and there was a lower loss of marginal bone around implants receiving immediate loading, thus achieving a better performance than the traditional implants-supported complete metal-structure prostheses.

The AHRLAC aircraft is a high performance light aircraft that is developed and manufactured in South Africa by Aerosud ITC in partnership with Paramount. This aircraft is the first of its kind to originate from South Africa. The aircraft has a twin boom, tandem pilot seating configuration, with a Pratt and Whitney turbine-propeller engine in a pusher configuration. The main structure of the aircraft is a conventional metallic structure, while the fairings and some secondary structures are composite. This study will focus on the design and development of the composite ventral fin of the first prototype aircraft, the experimental demonstrator model (XDM). It is crucial to ensure that the ventral fin can function safely within the design requirements of the aircraft under the loads which the fin is likely to encounter. Preceding the design process, a critical overview of composite materials used in aircraft applications is provided. This will include the materials, manufacturing methods, analysis and similar work done in this field of study. The literature will be used in the study for decision-making and validation of proven concepts and methodologies. The first part of this study entailed choosing a suitable composite material and manufacturing method for this specific application. The manufacturing method and materials used had to suit the aircraft prototype application. The limitations of using composite materials were researched as to recognize bad practice and limit design flaws on the ventral fin. Once the material and manufacturing methods were chosen, ventral fin concepts were evaluated using computer aided finite element analysis (FEA) with mass, stiffness and strength being the main parameters of concern. The load cases used in this evaluation were given by the lead structural engineer and aerodynamicist. The calculations of these loads are not covered in detail in this study. The FEA input material properties used, were determined by material testing by the relevant test methods. The ventral fin concept started as the minimal design with the lowest mass. The deflections, composite failure and fastener failure were then evaluated against the required values. The concept was modified by adding stiffening elements, such as ribs and spars, until satisfactory results were obtained. In this way a minimal mass component is designed and verified that it can adequately perform its designed tasks under the expected load conditions. Each part used in the ventral fin assembly was not individually optimized for mass, but rather the assembly as a whole. The final concept was modelled using the computer aided design software, CATIA. This model used in combination with a ply book made it possible to manufacture the ventral fin in a repeatable manner. A test ventral fin was manufactured using the selected materials and manufacturing methods to validate the design methodology. In the next step the selected load cases were used in static testing to validate the FEM through comparison. The result of the study is a composite ventral fin of which the mass, stiffness and strength are suitable to perform its function safely on the first prototype AHRLAC aircraft. The study concludes on the process followed from material selection to FEA and detail design, in order for this same method to be used on other AHRLAC XDM composite parts.
M (Mechanical Engineering), North-West University, Potchefstroom Campus, 2015

A reabilitação de edifícios é uma prática cada vez mais comum no seio da Engenharia Civil. Por esta razão torna-se imprescindível a procura de novas técnicas e métodos de reforço capazes de integrar construções já existentes. Nesse sentido, desenvolveu-se um estudo experimental sobre o confinamento de pilares de betão, de secção circular, com recurso a uma argamassa reforçada por uma malha têxtil unidirecional de fibras de carbono. O principal objetivo deste trabalho é fazer uma caracterização do CFRCM (Carbon Fabric Reinforced Cementitious Matrix) enquanto sistema de confinamento. Os compósitos de fibras, nomeadamente os CFRP (Carbon Fiber Reinforced Polymer), têm uma grande procura no mercado da construção porém apresentam algumas desvantagens que podem ser colmatadas por esta técnica inovadora que combina os compósitos com uma matriz inorgânica. A campanha experimental compreendeu a realização de ensaios de compressão uniaxial até à rotura de doze modelos, dos quais dois diziam respeito a modelos de referência que não foram reforçados. Relativamente aos modelos reforçados, estes dividem-se em duas séries, uma reforçada com tecidos de fibras de carbono a outra com argamassa reforçada com malha têxtil de fibras de carbono. Em ambas as séries fez-se variar o número de camadas. A aplicação do reforço foi feita em toda a altura dos pilares, com os tecidos de fibras e a malha têxtil orientadas na direção transversal dos pilares. Analisaram-se os resultados experimentais, mediante vários parâmetros que caracterizam o comportamento do betão confinado à compressão. Para ambos os reforços, foi possível aumentar a força máxima de compressão do betão e a correspondente extensão axial. O reforço de CFRCM apresentou algumas vantagens, nomeadamente a sua resposta pós pico, que suporta grandes deformações até perder toda a sua capacidade resistente e também a facilidade na aplicação do reforço face ao CFRP.
Building rehabilitation is an increasingly common practice in Civil Engineering. Thus, the search for new strengthening methods and techniques, adequate for existing constructions, is essential. With this in mind, an experimental study was carried out on the confinement of concrete columns, with circular section, using a mortar reinforced by an unidirectional carbon fiber textile mesh. The main objective of this study is to characterize the CFRCM (Carbon Fabric Reinforced Cementitious Matrix) as a confinement system. Fiber composites, namely CFRP (Carbon Fiber Reinforced Polymer), are in great demand for strengthening purposes, but they present some disadvantages that can be overcome by this innovative technique that combines composites with an inorganic matrix. The experimental testing campaign consisted of a sequence of uniaxial compression failure tests, using twelve specimens, two of which were reference unstrengthened models. The strengthened specimens, were divided into two series, one strengthened with carbon fiber sheets and another with mortar reinforced with a carbon fiber textile mesh. In both series, the number of layers were varied. The strengthening was applied over the whole height of the columns, with the fibers of the jackets and the textile mesh oriented in the transverse direction of the columns. The experimental results were analyzed using several parameters that characterize the compressive behavior of confined concrete. Both strengthening solutions made possible to increase the maximum load and the corresponding axial strain. The CFRCM reinforcement presented some advantages, namely its post-peak response, supporting larger deformations until losing all its load bearing capacity, but also its simpler application when compared with the CFRP alternative.

碩士
國立中央大學
化學研究所
87
Abstract Chlorofluorocarbons (CFCs) have been shown to be the primary agents responsible for the observed ozone depletion in the stratopheric. This occurs because chlorine from the CFCs is released by UV photolysis in the stratophere where it is then available to participate in catalytic cycles to destructive ozone. Following the implementation of the Montreal Protocol and its subsequent amendments in regulating the emissions of the CFCs, the atmospheric abundance and growth rate have steadily declined. Conversely, the atmospheric concentrations of their CFCs replacements such are the HCFCs and HFCs have grown rapidly. HFCFs and HFCs have shorter atmospheric lifetimes due to tropopheric oxidation by reaction with atmospheric hydroxyl radicals. These compounds have zero or near zero ozone depletion potentials. However, these two types of species have very large IR absorption cross－sections, as a result their Global Warming Potentials(GWP) are significant. Others have noted that certain HCFCs and HFCs will degrade in the atmosphere to produce long-lived compounds such as TFA(trifluoroacetic acid), which may adversely affect biota at sufficient high concentrations. In the past, GC/ECD are used to monitor and analyze atmospheric CFCs, however, ECD exhibit extremely low electron－affinity for detection of HCFCs and HFCs. Thus, GC/MS became the only option in the measurement of these compounds. Because of their extremely low concentrations in the atmosphere (e.q. lower than 10 pptv for HFC-134a and 120 pptv for HCFC-22), the selective ion monitoring (SIM) was used by targeting two characteristic mass fragments for each species. We have set up apparatus using HP6890GC/5973MS combining with a self-assembled cyro-preconcentration system to qualitatively analyze ambient HFC-134a and HCFC-22.