Thèses : « Durable materials »

1

Minardi, Lisa M. « Of massive stones and durable materials architecture and community in eighteenth-century Trappe, Pennsylvania / ». Access to citation, abstract and download form provided by ProQuest Information and Learning Company ; downloadable PDF file 1.51 Mb., 132 p, 2006. http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&res_dat=xri:pqdiss&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&rft_dat=xri:pqdiss:1435853.

Texte intégral

Styles APA, Harvard, Vancouver, ISO, etc.

2

Jin, Yanya. « Development of materials criticality profiling methodology at product level ». Thesis, Troyes, 2017. http://www.theses.fr/2017TROY0004/document.

Texte intégral

Résumé :

Les impacts causés par la crise des terres rares en 2010 mettent en évidence l’importance des matériaux et ont conduit en un intérêt accru dans la recherche sur leur criticité. Cette thèse s’ouvre par un état de l’art qui présente et évalue les travaux existants dans ce domaine et met en évidence trois lacunes de la recherche sur la criticité des matériaux (l’absence d’un véritable diagnostic de criticité; l’absence d’une méthodologie d’évaluation de la criticité au niveau produit; le défaut de lien bien établi entre mécanisme de criticité, méthode d’évaluation et solutions proposées). En conséquence, la thèse comble les deux premières lacunes et offre plusieurs pistes à l’égard de la troisième. Concernant le diagnostic de la criticité d’un matériau, la thèse propose d’illustrer le mécanisme de criticité par quatre dimensions : le déséquilibre entre offre et demande ; l’importance du matériau pour le produit ; l’accessibilité de l’approvisionnement ; et les facteurs dynamiques. Une définition de la criticité est proposée. Le mécanisme de criticité étant au centre de la recherche, une méthodologie permettant de déterminer la criticité matérielle à l’échelle « produit » est développée et complétée par un modèle applicatif quantitatif. La méthodologie offre un raisonnement général pour conduire une étude de la criticité ; le modèle illustre une de ses possibilités d’être appliqué à des cas réels pour déterminer quantitativement la criticité. A la fin, l’application du modèle à deux produits (l’aimant permanent et la diode électroluminescente) est présentée
Rare earth crisis in 2010 showed the importance of some materials and whipped up interest in the research on material criticality. A review work was first conducted in order to get a better understanding of the existing work in this research area and to see where more work is needed. Based on this review, three research gaps were identified (lack of a comprehensive diagnosis of criticality; lack of evaluation methodology at the product level; lack of links between the mechanism of criticality, the evaluation methodology and the solutions offered. This thesis focuses on the two first research gaps and offers several ideas for the last one. Regarding diagnosis of criticality, the mechanism is illustrated under four dimensions: imbalance between supply and demand, importance of the material to product, supply accessibility and dynamic factors. A definition of criticality is also put forward. Considering the established mechanism as research core, a methodology to evaluate the criticality of materials at the product level has been developed and is completed with a concrete and quantitative model. The methodology offers guidance on how to assess criticality and sets a framework for evaluation. The model illustrates a way to use this methodology through a tool that assigns a ‘criticality score’ to materials and shows how the score is contributed. The calculations were automated in Excel. Two applications, one for permanent magnet and the other for light emitting diode, were conducted to demonstrate and improve the methodology and the model

Styles APA, Harvard, Vancouver, ISO, etc.

3

Nicholls, J. C. « Extending the range of durable road surfacings that both provide safety and minimise environmental impact ». Thesis, University of Ulster, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.299083.

Texte intégral

Styles APA, Harvard, Vancouver, ISO, etc.

4

Manley, Alan H. G. « Attitudinal perception of cosmetic wear and damage of materials within the use phase of portable electronic products ». Thesis, Loughborough University, 2018. https://dspace.lboro.ac.uk/2134/36225.

Texte intégral

Résumé :

During the use phase of products, a series of obsolescing factors contribute to why a product is disposed of. Currently the visual state of a product is considered primarily in terms of aesthetic obsolescence which is synonymous with influential factors such as changes in fashion or personal preferences in style. The physical condition of a product is not commonly understood within the context of product replacement and the physical changes due to use are not understood fully. The research contributes to and provides original empirical research findings for the current literature on product lifetime extension, material semantics, the circular economy, emotionally durable design and material culture. Through an initial exploratory study (Photographic Analysis (PA) Study) of previously unexplained types of wear and damage that occur on portable electronic devices a taxonomy of damage (TOD) was established which provided the nomenclature for further studies. The second study (Retrospective Assessment (RA) Study) established the attitudes to wear based on the wear type, location, material and the stage during ownership that the wear occurred at. The RA Study highlighted the differences in the attitudinal responses to differing types of wear and damage and identified the differences in the temporal assessments of wear and damage. A third study (Real Time Assessment (RTA) Study) aimed to confirm or repudiate the findings found in the RA Study. The focus during the study was attitudes to the wear and damage in relation to the differences in materials, the location of the wear and the type of wear and damage was also looked at and led to a fuller understanding of how products and materials are perceived during the use phase; a stage of the product lifetime that is not currently well understood in terms of users aesthetic or cosmetic sensibilities. The final study (Semantic Perception of Materials (SPM) Study) focused on the visual and tactile perceptions of materials. The study established attitudinal perceptions of wear and damage of materials with a quantitative research methodology which has produced a better understanding of material semantics within the context of electronic objects. Through the four studies, discussion topics arose and major findings of the doctoral study were drawn out and seen to be interesting enough for further research and study. These discussions include the importance of including cosmetic obsolescence into the lexicon of product obsolescence and product lifetime extension literature, the differences in the perceptions of materials when they are within the context of a product or being assessed as samples, how differing product contexts affect user perceptions of wear and damage on materials and the potential inclusion of a material wear index that could inform the material selection process that goes further than the technical aspects outlined in current material selection tools and literature.

Styles APA, Harvard, Vancouver, ISO, etc.

5

Lin, Shun Yuk. « Synthesis and characterization of nano-emulsion for the enhancement of mechanical properties of durable press finishing cotton apparels / ». View abstract or full-text, 2005. http://library.ust.hk/cgi/db/thesis.pl?CENG%202005%20LIN.

Texte intégral

Styles APA, Harvard, Vancouver, ISO, etc.

6

Monsaingeon, Baptiste. « Le déchet durable : éléments pour une socio-anthropologie du déchet ménager ». Thesis, Paris 1, 2014. http://www.theses.fr/2014PA010654/document.

Texte intégral

Résumé :

Depuis une quarantaine d’années, les déchets ménagers et leur gestion sont assimilés à un enjeu écologique global. Alors que se popularisent les discours défendant une conception durable du développement, nos poubelles se multiplient. Qu’aspirons-nous à préserver lorsque, l’enjeu planétaire invoqué, un gouffre intermédiaire se dessine et nous invite à interroger ce lien communément admis entre déchets et pratiques de protection de l’environnement. Notre thèse consiste à affirmer que, sous couvert de leur « environnementalisation », et malgré l’inflation du temps et de l’espace qui leur sont consacrés, les déchets restent marqués par l’oubli des enjeux sociaux, techniques, matériels qui les caractérisent. Cet aveuglement, individuel et collectif, neutralise toute possibilité de penser le déchet comme indice : il voile sa fonction mémorielle et le condamne à n’être appréhendé que comme ce qui doit disparaître, que comme quantité de matière à contrôler, à éliminer. Le déchet durable est l’oxymore qui vise à problématiser cette multiplicité des modes de présence du déchet aujourd’hui. S’inspirant des figures du chiffonnier ou de l’archéologue, notre enquête socio-anthropologique s’applique à suivre ces déchets ménagers, depuis d’incertains océans de plastique jusqu’à quelques lombricomposteurs parisiens. A partir de cette confrontation à la matérialité, aux territoires et aux pratiques du déchu, il s’agit d’affirmer que là où la présence irrévocable des déchets est décrite comme un problème, la question de notre présence aux déchets se pose inévitablement
Over the past forty years, household waste and its management have been assimilated to a global environmental issue. While sustainable development is becoming a pressing issue, the number of our garbage bins is increasing. So what is it that we aim to preserve when we are dutifully sorting out our garbage? Between the very local gesture of discarding and the global environmental issue, there is a tremendous gap. The link between everyday practices of waste and environmental issues is so underdetermined that it has to be analysed. The main claim of this dissertation is that despite a growing concern with environment and the increasing time and space devoted to waste management, we remain unaware of the social, technological and material issues at stake. Because of this individual and collective blindness waste is not seen as a clue: as its memorial function is neglected waste is still perceived as what has to disappear, as a material quantity that has to be controlled and eliminated. The en-durable waste is an oxymoron that leads to further investigate the multiple modes of presence of waste in today’s life. Inspired by the personae of the ragman and of the archaeologist, this socio-anthropological investigation follows household waste from uncertain oceans of plastic to few Parisian vermicompost bins. Based on this confrontation to the materiality of waste, to the territories and to practices of wasting, this dissertation claims that where the unavoidable presence of waste is described as a problem, it is question of our presence to waste that is at stake

Styles APA, Harvard, Vancouver, ISO, etc.

7

Zhu, Honggang. « Development of epoxy-organoclay nanocomposite as high performance coating and as matrix material of durable GFRP composite for civil engineering applications / ». View abstract or full-text, 2009. http://library.ust.hk/cgi/db/thesis.pl?CIVL%202009%20ZHU.

Texte intégral

Styles APA, Harvard, Vancouver, ISO, etc.

8

Yao, Yuan. « Performance and mechanism on a high durable silica alumina based cementitious material composed of coal refuse and coal combustion byproducts ». Scholarly Commons, 2012. https://scholarlycommons.pacific.edu/uop_etds/155.

Texte intégral

Résumé :

Coal refuse and combustion byproducts as industrial solid waste stockpiles have become great threats to the environment. Recycling is one practical solution to utilize this huge amount of solid waste through activation as substitute for ordinary Portland cement. The central goal of this dissertation is to investigate and develop a new silica-alumina based cementitious material largely using coal refuse as a constituent that will be ideal for durable construction, mine backfill, mine sealing and waste disposal stabilization applications. This new material is an environment-friendly alternative to ordinary Portland cement. The main constituents of the new material are coal refuse and other coal wastes including coal sludge and coal combustion products (CCPs). Compared with conventional cement production, successful development of this new technology could potentially save energy and reduce greenhouse gas emissions, recycle vast amount of coal wastes, and significantly reduce production cost. A systematic research has been conducted to seek for an optimal solution for enhancing pozzolanic reactivity of the relatively inert solid waste-coal refuse in order to improve the utilization efficiency and economy benefit for construction and building materials. The results show that thermal activation temperature ranging from 20°C to 950°C significantly increases the workability and pozzolanic property of the coal refuse. The optimal activation condition is between 700°C to 800°C within a period of 30 to 60 minutes. Microanalysis illustrates that the improved pozzolanic reactivity contributes to the generated amorphous materials from parts of inert aluminosilicate minerals by destroying the crystallize structure during the thermal activation. In the coal refuse, kaolinite begins to transfer into metakaol in at 550°C, the chlorite minerals disappear at 750°C, and muscovite 2M 1 gradually dehydroxylates to muscovite HT. Furthermore, this research examines the environmental acceptance and economic feasibility of this technology and found that this silica alumina-based cementitious material not only meets EPA requirements but also shows several advantages in industrial application.

Styles APA, Harvard, Vancouver, ISO, etc.

9

Chen, Tao. « UTILIZATION OF BIO-RENEWABLE LIGNIN IN BUILDING HIGH CAPACITY, DURABLE, AND LOW-COST SILICON-BASED NEGATIVE ELECTRODES FOR LITHIUM-ION BATTERIES ». UKnowledge, 2017. http://uknowledge.uky.edu/cme_etds/75.

Texte intégral

Résumé :

Silicon-based electrodes are the most promising negative electrodes for the next generation high capacity lithium ion batteries (LIB) as silicon provides a theoretical capacity of 3579 mAh g-1, more than 10 times higher than that of the state-of-the-art graphite negative electrodes. However, silicon-based electrodes suffer from poor cycle life due to large volume expansion and contraction during lithiation/delithiation. In order to improve the electrochemical performance a number of strategies have been employed, such as dispersion of silicon in active/inactive matrixes, devising of novel nanostructures, and various coatings for protection. Amongst these strategies, silicon-carbon coating based composites are one of the most promising because carbon coating is comparatively flexible, easy to obtain, and scalable with various industrial processes. Low cost and renewable lignin, which constitutes up to 30% dry mass of the organic carbon on earth, is widely available from paper and pulp mills which produce lignin in excess of 50 million tons annually worldwide. It is a natural bio-polymer with high carbon content and highly interconnected aromatic network existing as a structural adhesive found in plants. Generally burnt for energy on site, lignin is gradually finding its way into high value-added products such as precursor for carbon fibers, active material in negative electrodes, and raw material for supercapacitors. This dissertation focuses on high performance silicon-based negative electrodes utilizing lignin as the carbon precursor for conductive additive, binder, and carbon coating. To my knowledge this is one of the first works attempting to utilize and summarize the performance of lignin in silicon-based negative electrodes. The first part of the dissertation shows that silicon-lignin composites treated at 800 ºC displayed good capacity and cycling performance. The second part goes to generalize the effect of temperature on silicon-lignin composites and shows that a low temperature treatment granted an electrode with superior performance and cycling properties owing to the preservation of polymeric properties of lignin. The final part of the dissertation discusses the current research trends in SiOx based negative electrodes and extends lignin to that field. This dissertation will, hopefully, provide knowledge and insight for fellow researchers wishing to utilize lignin or other renewable resources in devising advanced battery electrodes.

Styles APA, Harvard, Vancouver, ISO, etc.

10

Glogic, Edis. « Vers des matériaux énergétiques durables : élargissement de l'analyse du cycle de vie pour le développement de technologies émergentes et des choix économes en ressources ». Thesis, Bordeaux, 2019. https://tel.archives-ouvertes.fr/tel-02869841.

Texte intégral

Résumé :

Les matériaux énergétiques sont particulièrement intéressants du point de vue du développement durable pour faire progresser les systèmes d’énergie renouvelable, notamment les énergies de production et de stockage. Leurs utilisations appropriées ainsi que leur développement requièrent une méthode d’évaluation quantitative. L’Analyse de Cycle de Vie (ACV) est une méthode qui soutient le développement durable par l’identification de priorités environnementales ainsi que par la comparaison de différentes technologies. Cette recherche vise à soutenir le développement des matériaux énergétiques et de faire de la méthode d'analyse du cycle de vie un outil plus pertinent pour l'évaluation environnementale à travers l’extension de son usage dans deux directions émergentes : l’évaluation des technologies au début de leur développement et le soutien des choix économes en ressources dans le contexte d'une économie circulaire.Les objectifs de recherche se focalisent sur le développement de l’information relatives aux technologies ainsi que sur la méthodologie d’identification des défis et opportunités par l’application de l’ACV sur trois études de cas de technologie énergétique à différents niveaux de maturité. Dans le premier cas d’étude, les piles alcalines, actuellement à haut niveau de maturité () sont évalué grâce à l’utilisation de l’ACV combiné avec un indicateur d’économie circulaire, l'indicateur de circularité du matériau (MCI). Le but était d’explorer une opportunité de couplage des deux méthodes ainsi que les compromis entre les indicateurs pour différentes stratégies de conception et de gestion de ces batteries. Dans le deuxième cas d’étude, les électrodes à base d’hydroxyde de nickel-cobalt, à présent à bas niveau de maturité (échelle de laboratoire) sont évaluées dans l’optique d’étudier des priorités environnementales des voies de synthèse favorables. Dans le troisième cas d’étude, les chargeurs organiques photovoltaïques portables pour petits équipements éléctroniques, actuellement à un niveau de maturité intermédiaire (échelle pilote), sont évalués pour remplacement du réseau électrique traditionnel pour le chargement de téléphones portables
Energy materials are particularly important from a sustainability perspective for advancing renewable energy systems, including energy production and storage. Their appropriate use and development require quantitative assessment methods. Life Cycle Assessment (LCA) is a method to support sustainable development that can be used to identify environmental hotspots and compare different technologies. The purpose of this research is to support development of several energy materials and make LCA a more relevant tool for sustainability assessment by extending its use in two emerging directions: assessment of technologies at the early stage of development, and by supporting more resource-effective choices for a circular economy.The research objectives focus on informing the development of technologies and identifying methodological challenges and opportunities by applying LCA to three energy-technology case studies, each at a different technological maturity level. In the first case study, alkaline batteries, currently at a high maturity level (incumbent products), are evaluated using LCA in combination with a circular economy indicator, the Material Circularity Indicator (MCI). The aim was to investigate opportunities to combine the two methods, while considering trade-offs between indicators for different strategies for battery design and management. In the second case study, nickel-cobalt hydroxide charge storage electrodes, currently at a low maturity level (laboratory-scale), are evaluated to investigate environmental hotspots and preferred synthesis route. In the third case study, organic photovoltaic portable chargers for small electronics, currently at a medium maturity level (pilot-scale), are evaluated for replacing conventional electricity grid for charging a mobile phone

Styles APA, Harvard, Vancouver, ISO, etc.

11

Youssef, Nicolas. « Mise en place d’une brique géopolymère pour la construction durable : études géotechnique, environnementale et économique ». Thesis, Ecole centrale de Lille, 2019. http://www.theses.fr/2019ECLI0005.

Texte intégral

Résumé :

Après la crise économique en 2008, l’activité de construction en France a connu une croissance très rapide. La hausse de la demande des matériaux de construction était accompagnée d’une augmentation des quantités de déchets de construction et de CO2 émise. En 2018, l’émission de CO2 liée aux activités humaines a atteint un niveau historique mondial de 37.1 milliards de tonnes. Ceci encourage le développement des matériaux de construction qui répondent aux besoins mutants de la société d’aujourd’hui et de demain. Les géopolymères, préparés par activation alcaline, présentent une opportunité pour produire des nouveaux matériaux plus performants et respectueux de l’environnement dans le secteur de la construction. D’autre part, l’industrialisation et la robotisation font apparition dans le secteur de la construction, avec des nombreux avantages tels que l’augmentation de la productivité, la réduction des gaspillages, du coût et de la pénibilité du travail, ainsi que l’amélioration de la qualité et la sécurité.Ce travail de recherche est mené pour répondre à ces défis et verrous scientifiques. Il est réparti selon trois axes : l’élaboration de nouvelles formulations de briques géopolymères, l’intégration des matériaux géopolymères dans le processus d’industrialisation et de robotisation de la construction, et enfin l’évaluation de l’impact environnemental et économique du nouveau système de fabrication automatisé
After the economic crisis in 2008, construction activity in France grew rapidly. The increase in demand for building materials was accompanied by an increase in the quantities of construction waste and emitted CO2. In 2018, CO2 emissions from human activities reached a world historic level of 37.1 billion tons. This encourages the development of building materials that meet the changing needs of today's and tomorrow's society. Geopolymers, prepared by alkaline activation, present an opportunity to produce new, more efficient and environment-friendly materials in the construction sector. On the other hand, industrialization and robotization are emerging in the construction sector, with many benefits such as increased productivity, reduced waste, cost and arduous work, as well as improved quality and safety.This doctoral thesis is being conducted to address these scientific challenges and issues. These are divided into three research directions: the development of new geopolymer brick formulations, the integration of geopolymer materials into the industrialization and robotization of construction processes, and finally the environmental and economic assessment of the new automated manufacturing system

Styles APA, Harvard, Vancouver, ISO, etc.

12

Khoshbinroudi, Farangis. « La ville traditionnelle iranienne : conception compacte et bioclimatique en zone aride ». Thesis, Université Paris-Saclay (ComUE), 2019. http://www.theses.fr/2019SACLD005.

Texte intégral

Résumé :

Une grande part de la consommation énergétique des bâtiments en Iran provient du pétrole, du gaz et de l'électricité, alors même que les ressources en énergies fossiles s'épuisent dans le pays. De plus, la consommation énergétique moyenne y est plus importante que dans d'autres pays, y compris des pays qui disposent de ressources importantes en énergies fossiles, tandis que les subventions accordées par le gouvernement Iranien renforce encore cette tendance en rendant bon marché sur le marché intérieur les prix du pétrole et du gaz. Bâtiments et maisons représentent une part moyenne importante de l'énergie totale consommée dans le pays, à hauteur de 42%, et les énergies renouvelables ne sont utilisées que de façon marginale. En contraste, les villes Iraniennes avaient, depuis des milliers d'années, su s'appuyer sur des techniques de construction, d'architecture et d'urbanisme leur permettant de revendiquer un profil de faible consommation énergétique, instaurant ainsi un équilibre durable avec leur environnement. Cette recherche s'attache à comprendre les principes et les techniques utilisés dans la conception de l'architecture urbaine traditionnelle de la ville de Yazd, située dans le centre de l'Iran, afin de fournir des éléments précis d'optimisation énergétique des espaces urbains. Cette recherche s'avère fondamentale en termes d'orientation, avec l'objectif d'atteindre des résultats applicables dans le contexte contemporain en utilisant une méthode exploratoire. Le recueil des données nécessaires à cet exercice a été réalisée en deux temps. Dans un premier temps, par une méthode documentaire s'appuyant sur des textes historiques, sur des écrits d'historiens reconnus comme autoritaires, et sur l'étude de plans et de cartes détaillants le développement urbain. Dans un second temps, par une investigation conduite directement sur le terrain ainsi que par des rencontres avec des professionnels et des universitaires. S'appuyant sur l'ensemble des données recueillies, l'analyse de la situation actuelle dans la zone étudiée a été réalisée en utilisant la méthode de description qualitative. Finalement, tenant compte du système centralisé de gestion urbaine en Iran, nous avons proposé de mettre à disposition le fruit de notre étude auprès des entités administratives compétentes
Most of the energy consumption of buildings in Iran comes from oil, gas and electricity sources, while fossil fuel resources are running out in Iran. In addition to that, the country's average energy consumption is higher than other countries and even some oil-rich countries, while government subsidies and cheap oil and gas resources has exacerbated this critical situation. Buildings and houses with an average consumption share of 42.41 percent has a high share of energy consumption of the country and renewable energies are used only marginally. In contrast to this situation, Iranian cities, for thousands of years, have had a low consumption pattern of energy with the use of architectural and urban construction techniques and have come to a permanent and sustainable coexistence with their surroundings. This research seeks to understand the principles and techniques of constructing the traditional urban architecture of Yazd in the centre of Iran to provide in-depth insights toward energy optimization in urban areas. Moreover, the global methods of sustainable urban development are studied and compared to extract a set of guidelines for improving urban conditions in the traditional areas of Yazd. This research is fundamental in terms of orientation, and the purpose is exploration and being applicable. The compilation of the required data is done in two ways firstly) documentary method with the use of historical texts, authoritative writings of historians, and review of urban development plans such as comprehensive and detailed plans, and secondly field observations and meetings with practitioners and faculties have been conducted. Based on the gathered information, analysis of the current situation in the studied area has been carried out using qualitative descriptive method. Finally, with the consideration to the centralized urban management system of Iran, we proposed a method for transferring these results to the administrative sectors?

Styles APA, Harvard, Vancouver, ISO, etc.

13

Navaro, Julien. « Cinétique de mélange des enrobés recyclés et influence sur les performances mécaniques ». Phd thesis, Paris, ENSAM, 2011. http://pastel.archives-ouvertes.fr/pastel-00613982.

Texte intégral

Résumé :

Les acteurs du domaine des travaux publics participent techniquement au développement durable, en diminuant les consommations de matériaux et d'énergie lors de la fabrication à chaud d'enrobés bitumineux. Le recours accru aux agrégats d'enrobé, matériaux provenant de la déconstruction des chaussées, est une solution qui permettra d'atteindre une pleine capacité de recyclage dans le secteur de la construction routière. La concomitance de l'augmentation du niveau de recyclage avec l'abaissement des températures de fabrication, avec le même objectif de réduction de la consommation énergétique, suscite une interrogation engageant la qualité des enrobés recyclés ainsi produits. Leur caractérisation qualitative passe par la validation de leurs propriétés mécaniques et une connaissance de l'état physicochimique des constituants. À cette fin, des études mécaniques et des observations microscopiques se complétant sont réalisées. La mise en parallèle de ces résultats avec un essai pratique de contrôle validera la qualité de l'enrobé recyclé produit lors d'une fabrication industrielle. La maitrise des performances des enrobés recyclés permettra leur développement industriel dans le respect des engagements environnementaux contemporains.

Styles APA, Harvard, Vancouver, ISO, etc.

14

Bouasria, Manal. « Develοpment and mοnitοring οf the mechanical and hygrοthermal perfοrmance οf lοw-carbοn materials by smart technοlοgy ». Electronic Thesis or Diss., Normandie, 2022. http://www.theses.fr/2022NORMC247.

Texte intégral

Résumé :

La distribution des émissions de gaz à effet de serre et de la consommation d'énergie des bâtiments a été estimée à 30 % en phase de construction, 70 % en phase d'exploitation et d’entretien et 1 % en phase de démantèlement. Pendant la phase de construction, les matériaux utilisés représentent 56 % des émissions de CO2. Par conséquent, de nombreuses mesures sont prises en compte lors de la construction, telles que : l'émergence du concept de l’économie circulaire, le choix des matériaux à faible teneur en carbone, l’utilisation des déchets, l’utilisation de matériaux intelligentes, réutilisation des matériaux lors de la démolition.Ainsi, l'objectif de cette thèse est de développer des matériaux à faible impact environnemental. Des essais de caractérisation physique, chimique, hygrothermique et mécanique sont réalisés à différentes échelles. Un prototype sera créé et une preuve de concept sera créée pour vérifier l’efficacité des matériaux bas carbone développés dans cette thèse.Dans ce contexte, nous avons d'abord étudié le comportement de mélanges cimentaires incluant des sous-produits. Nous avons substitué le ciment par plusieurs déchets, à savoir les laitiers de ferronickel (FNS) associé à des coquilles de crépidule (CR) et des cendres volantes (FA) associés à des coquilles de crépidule. Des études mécaniques, thermiques ont été menés à la fois à l’échelle du matériaux (mortier et béton) et aussi sur un prototype à l’échelle du laboratoire. Les propriétés mécaniques du mortier avec une utilisation de FA-CR en substitution du ciment se sont avérées supérieures à celles du mortier et du béton ordinaires. Le prototype à base de ce nouveau matériau bas carbone a été développé pour surveiller le comportement hygrothermique avec des modèles des réseaux de neurones artificiels. Les résultats de l'expérience sur le risque de condensation et le développement de moisissures révèlent que le mélange de béton choisi peut empêcher la condensation.Dans ce travail de thèse, nous nous sommes intéressés aussi à la stabilisation de la construction en terre par un liant cimentaire et ensuite par un liant organique. Dans la première partie, nous avons étudié la pertinence de la boue de lavage de gravier et des coquillages comme matériau de construction en terre non cuite tout en utilisant des cendres volantes comme liant et stabilisateur cimentaire. Nos résultats montre que ce mélange conduit à une réduction de la porosité, une augmentation des performances mécaniques, une diminution de la conductivité thermique avec une capacité thermique spécifique plus élevée. Dans la deuxième partie, nous avons utilisé de la poudre d'algues comme stabilisateur de la bauge. Nous avons étudié l'impact de la substitution de la terre par de la poudre d'algues (liant organique). Pour ce nouveau matériau à base d’algues, nous avons observé une amélioration de la capacité de stockage de la chaleur et de la conductivité thermique sans impacter les propriétés mécaniques. Le développement du réseau neuronal artificiel pour prédire les propriétés hygrothermiques du prototype terre-algues-fibres a montré une bonne similarité entre les résultats expérimentaux et le modèle. Enfin, le mécanisme de stabilisation de la terre a été étudié à l'aide de techniques d'analyse microstructurale (DRX et spectroscopie Raman)
The distribution of energy consumption and greenhouse gas emissions in buildings has been estimated at 30% during the construction phase, 70% during the use and maintenance phase, and 1% during the demolition process. During the construction phase, the materials used represent 56% of the CO2 emissions. The long term use of a building, difficult to control, depends on a large number of variables. Numerous levers are therefore studied to act during construction: low-carbon materials, waste reduction, promoting the circular economy, optimized design, intelligent material saving, construction and demolition waste, etc.Therefore, the objective of this PhD is to develop new low carbon materials. Physical, chemical, hygrothermal and mechanical characterization experiments are carried out at different scales. A prototype will be designed and a proof of concept will be created to verify the effectiveness of the eco-materials developed in this research.In this context, we started by studying the behaviour of cementitious mixtures including by-products. We substituted cement by several wastes, i. e. ferronickel slag (FNS) associated with crepidula shells (CR) and fly ash (FA) associated with crepidula shells. Mechanical and thermal properties of the mortar and concrete were studied at the material scale and also on a lab-scale prototype. The mechanical properties of the mortar with the use of FA-CR in substitution of cement were found to be superior to those of ordinary mortar and concrete. The prototype based on this new low carbon material was developed to monitor the hygrothermal behaviour with artificial neural network models. The results of the experiment on the risk of condensation and mold growth reveal that the chosen concrete mix can prevent condensation. Indeed, the high silica, aluminate, and calcium content of the smart Fly ash-Crepidula mixture reacts with water from humid ambient air to generate additional hydrates as a result of pozzolanic reaction, resulting in continual strength enhancement.In this thesis work, we were also interested by the stabilization of earthen construction using a cementitious binder and then by an organic binder. In the first part, we investigated the suitability of gravel washing sludge and seashells as an unfired earth construction material while using fly ash as a binder and cementitious stabilizer. Our results show that this mixture leads to a reduction in porosity, an increase in mechanical performance and a decrease in thermal conductivity with a higher specific heat capacity. In the second part, we used seaweed powder as a stabilizer for the cob construction. We studied the impact of substituting soil with seaweed powder (organic binder). For this new algae-based material, we observed an improvement in heat storage capacity and thermal performance without impacting mechanical properties. The development of the artificial neural network to predict the hygrothermal properties of the earth-algae-fiber prototype showed a good similarity between the experimental results and the model. Finally, the stabilization mechanism of the soil was studied using microstructural analysis techniques (XRD and Raman spectroscopy)

Styles APA, Harvard, Vancouver, ISO, etc.

15

Tran, Van Huong. « Optimisations mécaniques des constructions en matériaux locaux ». Electronic Thesis or Diss., Vaulx-en-Velin, École nationale des travaux publics de l’État, 2014. http://www.theses.fr/2014ENTP0014.

Texte intégral

Résumé :

Les matériaux locaux utilisés en génie civil se définissent comme présents directement sur les sites de construction ou lieux proches. Parmi ces matériaux, nous avons étudié la terre crue, la limousinerie (maçonnerie de pierre associée au mortier de terre de chaux maigre) et le béton de poudingue (un béton maigre à base de granulat de poudingue). L’objectif général de cette thèse est de faciliter l’utilisation des constructions durables en matériaux locaux. Les études à l’échelle du matériau et à l’échelle de la structure ont été effectuées sur ce type de construction. À l’échelle du matériau, le comportement mécanique des matériaux locaux a été étudié. Une procédure d’optimisation de la composition des matériaux en fonction de leur résistance mécanique a été également proposée. À l’échelle de la structure, le comportement des constructions en matériaux locaux a été étudié par les études de cas. Premièrement, le comportement mécanique d’un pont neuf, voûté en limousinerie, a été étudié en effectuant des mesures in situ du champ de déplacements du pont lors du décintrement. Le pont a également été modélisé par un modèle 2D utilisant la MED. La modélisation du phénomène de contacts partiels dans la zone des voussoirs adjacents du voussoir de clé a permis de retrouver le profil particulier du champ de déplacements mesuré, ce qui ne peut pas être effectué par la MEF. Deuxièmement, l’auscultation dynamique d’un bâtiment en limousinerie a été effectuée par des mesures de bruit de fond. Un modèle 3D utilisant la MEF a été fait et validé en le comparant avec les résultats expérimentaux. Une simulation des actions sismiques conformément à l’EC8 a été effectuée afin d’estimer sa vulnérabilité aux séismes. Troisièmement, le comportement d’une maison en béton de poudingue a été étudié. Une procédure d’optimisation de la forme de voûte a été proposée pour ce type de construction. Puis, les principes de justification de la stabilité par la méthode de calcul aux contraintes admissibles ont également été proposés
Local materials used in civil engineering are directly available on construction site or close places. Among these materials, we studied soil, the rubble stone masonry (stone masonry associated with clay mortar or lime mortar), and the pudding concrete. New constructions using local materials are promising to compete with conventional materials, due to their low embodied energy and reduction of waste. However, until now, these constructions remain limited in the world and particularly in France, due to difficulties of implementation: low strength, lack of design rules and implementation guide. Therefore, the general objective of this thesis is to facilitate the use of local material to build the sustainable constructions. So, study in material and structural scales has been done on this type of construction. At the scale of the material, the mechanical behavior of the local materials has been studied by determining their mechanical properties by laboratory tests. An optimization procedure for the composition of the materials according to their strength has also been proposed for earthen materials (compacted earth, mixed earth and concrete of pudding). At the structural scale, mechanical and dynamical behaviors of constructions using local materials have been studied on some structures. Firstly, the mechanical behavior of a new stone masonry bridge was studied by measuring its displacements at the stage of the formwork removal. The singular profile of the displacements field with a singularity for voussoirs very close to the keystone was found. A 2D numerical analysis of the formwork removal using DEM was proposed to provide better insight on mechanisms that took place on site. The reduction of the extent of the contact zone between the voussoirs enabled finding the peculiar displacement field observed on-site. Secondly, the dynamic behavior of an old rubble stone masonry building was studied by determining its dynamic characteristics using in-situ measurements of background noise. Then, a 3D numerical model using FEM was validated by comparing with experimental results. Seismic vulnerability of the building was also estimated by a simulation of the seismic actions in this model according to EC8. Thirdly, an optimization procedure for the arch shape was proposed in the case of concrete of pudding stone house. The principle of justification of the stability using the yield design analysis was also discussed

Styles APA, Harvard, Vancouver, ISO, etc.

16

Vo, Dong Phuong Anh. « Multi-objective optimization for ecodesign of aerospace CFRP waste supply chains ». Phd thesis, Toulouse, INPT, 2017. http://oatao.univ-toulouse.fr/19911/1/VODONG_PhuongAnh.pdf.

Texte intégral

Résumé :

Composites have been increasingly used in different applications in the last decade, especially in aerospace due to their high strength and lightweight characteristics. Indeed, the latest models of Airbus (A350) and Boeing (B787) have employed more than 50 wt% of composites, mainly Carbon Fibre Reinforced Polymers (CFRP). Yet, the increased use of CFRP has raised the environmental concerns about their end-of-life related to waste disposal, consumption of non-renewable resources for manufacturing and the need to recycle CFRP wastes. In this study, a generic model is developed in order to propose an optimal management of aerospace CFRP wastes taking into account economic and environmental objectives. Firstly, a life-cycle systemic approach is used to model the environmental impacts of CFRP recycling processes focusing on Global Warming Potential (GWP) following the guidelines of Life Cycle Assessment (LCA). The whole supply chain for recycling CFRP pathways is then modelled from aircraft dismantling sites to the reuse of recycled fibres in various applications. A multi-objective optimisation strategy based on mathematical programming, -constraint and lexicographic methods with appropriate decisionmaking techniques (M-TOPSIS, PROMETHEE-GAIA) has been developed to determine CFRP waste supply chain configurations. Various scenarios have been studied in order to take account the potential of existing recycling sites in a mono-period visions as well as the deployment of new sites in a multi-period approach considering the case study of France for illustration purpose. The solutions obtained from optimisation process allow developing optimal strategies for the implementation of CFRP recovery with recycled fibres (of acceptable quality) for the targeted substitution use while minimising cost /maximising profit for an economic criterion and minimising an environmental impact based on GWP.

Styles APA, Harvard, Vancouver, ISO, etc.

17

Fusteș-Dămoc, Iolanda. « Matériaux polymères durables synthétisés à base d'oligo- et de polysaccharides ». Electronic Thesis or Diss., Université Côte d'Azur, 2023. http://www.theses.fr/2023COAZ4076.

Texte intégral

Résumé :

La durabilité des matériaux est leur capacité à résister dans le temps à l'influence de divers facteurs tels que la température, l'humidité, la rupture, tout en conservant leurs caractéristiques.Les matériaux polymères durables sont la solution contre la pollution de l'environnement. Dans ce contexte, le développement de matériaux polymères durables basés sur des composés biodégradables, que l'on trouve en abondance dans la nature, même à partir de déchets industriels, et qui ont également un faible prix de revient, est une alternative possible aux matériaux basés sur des composés fossiles, qui sont toxiques. En même temps, l'utilisation d'un minimum de produits chimiques est un atout pour la production à grande échelle par les industries. En outre, l'obtention de propriétés avantageuses dans ces conditions, adaptées à certains types d'applications, ajoute de la valeur, ce qui recommande leur utilisation par rapport aux matériaux toxiques.Les oligo- et polysaccharides constituent une matière première appropriée qui pourrait être exploitée dans la conception de matériaux polymères durables. Leur utilisation a déjà suscité un réel intérêt de la part des chercheurs, mais leur application au niveau industriel se heurte à un certain nombre de difficultés : des procédés technologiques inadaptés et de la consommation élevée de solvants et de produits chimiques au coût élevé de l'obtention, du recyclage et de la réutilisation des matériaux, conformément à une économie circulaire, essentielle dans l'approche de la protection de l'environnement. Cette économie circulaire consiste à prolonger le cycle de vie des matériaux en réduisant les déchets. Elle privilégie la réparation, la réutilisation et le recyclage des matériaux le plus longtemps possible. Cette thèse de doctorat présente les résultats obtenus par la synthèse, la caractérisation et le test de matériaux durables à base d'oligo- et de polysaccharides.L'objectif global de la thèse de doctorat est de développer des matériaux durables qui intègrent et exploitent des composés non toxiques, renouvelables, respectueux de l'environnement, bon marché et abondants dans la nature tels que les oligo- et polysaccharides dans une économie circulaire.Les principaux axes de recherche développés dans la thèse sont:- Valorisation de la β-cyclodextrine, de la catégorie des oligosaccharides, et du chitosane, de la catégorie des polysaccharides, dans des systèmes de matériaux durables;- Développement de tels matériaux durables, en utilisant également un minimum d'étapes et un nombre réduit de composés et de solvants respectueux de l'environnement;- Utilisation, en particulier, du chitosane sous forme solide (poudre) pour optimiser les propriétés mécaniques et thermiques des systèmes;- Obtention de propriétés matérielles améliorées par l'introduction d'oligo- et de polysaccharides, par rapport aux systèmes de référence, pour les systèmes à base de chitosane: amélioration des caractéristiques mécaniques et thermiques, et pour les systèmes à base de β-cyclodextrine: optimisation de l'adsorption de divers polluants tels que les antibiotiques, les colorants organiques, les métaux lourds;- Augmenter le potentiel d'application des matériaux dans divers domaines tels que le biomédical, l'emballage alimentaire, les revêtements époxy, l'aérospatiale, en raison des avantages que possèdent les oligo- et les polysaccharides ;- Vérifier la recyclabilité des nanomatériaux à base de β-cyclodextrine afin d'améliorer la durabilité des matériaux
The durability of materials is their ability to withstand over time the influence of various factors such as temperature, humidity and breakage while maintaining their characteristics.Durable polymer materials are the solution to environmental pollution. In this context, the development of sustainable polymer materials based on biodegradable compounds, which are abundant in nature, even from industrial waste, and which also have a low cost price, is a possible alternative to materials based on fossil compounds, which are toxic. At the same time, the use of minimal chemicals is an advantage for large-scale production by industries. In addition, obtaining advantageous properties under these conditions, tailored to certain types of applications, brings added value, which recommends their use over toxic materials.Oligo- and polysaccharides represent a suitable raw material that could be exploited in the design of durable polymeric materials. Their use has already aroused real interest among researchers, but their industrial application faces a number of difficulties: from inadequate technological processes and high consumption of solvents and chemicals to the high costs of obtaining, recycling and reusing materials, in line with a circular economy, which is essential in addressing environmental protection. This circular economy is about extending the life cycle of materials by reducing waste. by promoting the repair, reuse and recycling of materials for as long as possible. This PhD thesis presents the results obtained from the synthesis, characterisation and testing of sustainable oligo- and polysaccharide-based materials.The overall objective of the PhD thesis is to develop durable materials that incorporate and exploit non-toxic, renewable, environmentally friendly, cheap and naturally abundant compounds such as oligo- and polysaccharides in a circular economy.The main research directions developed in the thesis are:- Valorisation of β-cyclodextrin, from the oligosaccharide category, and chitosan, from the polysaccharide category, in sustainable material systems;- Development of such sustainable materials using a minimum number of steps and a reduced number of compounds and solvents;- The use, in particular, of chitosan in solid (powder) form to optimise the mechanical and thermal properties of the systems;- Achieving improved mechanical and thermal properties of the materials by introducing oligo- and polysaccharides, compared to reference systems, for chitosan-based systems, and for β-cyclodextrin-based systems: optimised adsorption of various pollutants such as antibiotics, organic dyes, heavy metals;- increased application potential of materials in various fields such as biomedical, food packaging, epoxy coatings, aerospace, due to the advantages of oligo- and polysaccharides;- Testing the recyclability of β-cyclodextrin-based nanomaterials to improve material durability

Styles APA, Harvard, Vancouver, ISO, etc.

18

Ouedraogo, Kouka Amed Jérémy. « Stabilisation de matériaux de construction durables et écologiques à base de terre crue par des liants organiques et/ou minéraux à faibles impacts environnementaux ». Thesis, Toulouse 3, 2019. http://www.theses.fr/2019TOU30199.

Texte intégral

Résumé :

Dans un contexte de lutte contre le réchauffement climatique, le développement de la construction en terre crue est une véritable alternative en vue de la réduction de la part d'émission de CO2 du secteur du bâtiment. Toutefois, ce matériau millénaire doit pouvoir justifier de bonnes résistances mécaniques et d'une tenue à l'eau convenable dans des conditions particulièrement sévères qu'imposent les règlementations en vigueur. Pour ce faire, la plupart des applications industrielles et des travaux scientifiques à ce jour ont recours au ciment et la chaux pour la stabilisation de la terre crue. Mais l'empreinte carbone élevée de ces liants minéraux conjuguée à leur taux d'incorporation élevé posent des questions sur le caractère écologique de la terre crue stabilisée d'autant plus que les gains de performances sont faibles. Or, à travers certaines constructions anciennes et pratiques traditionnelles dans diverses régions du globe, l'usage de biopolymères a montré une efficacité. Ces liants organiques issus d'agro-ressources constitueraient donc des stabilisants prometteurs pour des constructions modernes en terre crue. Notre étude a pour objectif de proposer une stabilisation de la terre crue pour des constructions modernes avec un bon compromis entre les performances mécaniques, la tenue à l'eau et l'impact environnemental. Une discussion sur la pertinence de proposer des briques de terre crue stabilisée au ciment ou à la chaux éteinte comme alternative aux blocs en béton creux a permis de limiter le taux de liants incorporés à 4% par rapport à la masse sèche de terre. Des tests préliminaires réalisés sur neuf biopolymères ont permis d'identifier en amont quelques liants organiques prometteurs dont l'ovalbumine (protéine du blanc d'œuf) qui ne nécessite pas de pré-activation. Ainsi, ce liant organique de même qu'un ciment portland et une chaux éteinte ont été utilisés à 2 et 4% pour stabiliser deux sols fins argileux (B et N) issus de la région Occitanie mais de minéralogies différentes. Les résultats sur les résistances à la compression ont montré que la cure est nécessaire pour garantir l'efficacité des liants minéraux. L'augmentation de la densité de fabrication, au moins égale à celle des sols non stabilisés, améliore aussi de façon considérable l'efficacité de la stabilisation. La nature du sol à stabiliser a aussi son importance : l'amélioration des résistances à la compression à l'état sec est plus importante sur le sol B constitué essentiellement de kaolinite que sur le sol N composé de montmorillonite et de chlorite, par contre, pour la tenue à l'eau (résistance à la compression humide) c'est le traitement du sol N qui conduit aux meilleurs résultats. Au final, de toutes les formulations, seules celles avec 4% de ciment ou d'ovalbumine, à densité de fabrication égale à celle du sol seul, permettent de respecter les critères de résistances minimales aux états sec et humide donnés par la norme française sur les BTC (XP P 13-901, 2001, pp. 901-13). Sur le plan des performances hygrothermiques, nous avons observé que l'ajout des liants diminuait les capacités hygroscopiques des sols tout en restant " bonnes " selon le critère du Nordtest même à 4% d'ajout de liant. Il est à noter que l'ovalbumine réduit beaucoup plus que les autres liants l'hygroscopie des sols. La conductivité thermique mesurée sur les mélanges aux densités égales à la densité des sols seuls ne change pas, ce qui confirme les observations faites dans littérature à propos de la corrélation entre la densité des matériaux et leurs conductivités thermiques. Les mécanismes de stabilisations ont été recherchés en utilisant des techniques classiques d'analyse minéralogique (DRX, spectroscopie IR et TGA). Malheureusement, il n'a pas été possible de conclure compte tenu déjà des faibles teneurs en liant employées
In the climate change mitigation context, unfired earth materials are a valuable alternative to cement concrete for reducing the construction sector related CO2 emission. However, this millenary construction material still has to meet current standards on mechanical and water resistance requirements. Hence, most industrial applications and papers on unfired earth stabilization use cement and lime for the stabilization of earth. But (Van Damme et al., 2017) pointed out the fact the high embodied energy of mineral binders and the high amount used for earth stabilization lead to doubt about the environmental friendliness of those solutions given their low improvement of the mechanical strengths. Yet, ancient earthen buildings and vernacular construction techniques in the worldwide showed the stabilization potential of some biopolymers. The so-called organic binders are food industry byproducts, which use for ancient earthen building renovation and vernacular techniques are recently revealed in some studies. Our study aims to propose a stabilization of earth for modern buildings with a good compromise between mechanical and water resistance performance on the one hand, and environmental impact on the other hand. A discussion on the relevance of proposing unfired earth bricks stabilized with cement and hydrated lime as an alternative to hollow concrete blocks led to limit the binder's content to 4% wt. of the dry soil. Preliminary tests on nine biopolymers have identified a few promising organic binders upstream, including ovalbumin (egg white protein), which does not require pre-activation. Thus, this organic binder as well as Portland cement and hydrated lime were used at 0, 2, and 4% to stabilize two soils (B and N) from the Occitanie region with different mineralogical characteristics. The results on compressive strength showed that the curing is necessary to guarantee the effectiveness of the mineral binders. In addition, the increase in manufacturing dry density at least equal to that of unstabilized soils' ones considerably improves the effectiveness of the stabilization. The improvement in dry compressive strength is greater on soil B, which is mainly composed of kaolinite, than on soil N, which is composed of montmorillonite and chlorite. However, on water resistance (wet compressive strength), it is the soil N that is better. Overall the formulations, those with 4% cement and ovalbumin at a manufacturing density equal to that of the soils alone, comply with the minimum resistance criteria both in the dry and wet state given in the French standard (XP P 13-901, 2001) standard. The surprise of this study is that ovalbumin gives much better mechanical performances and better durability (water resistance) than cement and lime for the same contents. In terms of hygrothermal performance, we have observed that the addition of binders reduces the hygroscopic capacities of soils. But they remain good according to the Nordtest criterion up to 4% addition of binder. It's worth mentioning that ovalbumin reduces soil hygroscopy much more than other binders. The thermal conductivity measured on mixtures with densities equal to the density of soils alone does not change. This confirms the observations made in the literature about the correlation between the dry density of materials and their thermal conductivities. Classical mineralogical analysis techniques (XRD, IR spectroscopie, and TGA) were used in order to explain the mechanisms of the stabilizations. But they only highlighted the well-known mechamisms of the stabilization with mineral binders unlike the ones of ovalbumin for which further investigations are still required

Styles APA, Harvard, Vancouver, ISO, etc.

19

Regados, Ygor Amadeo Sartori. « Modelo matemático para previsão da macrossegregação durante a solidificação com zona pastosa ou interface sólido-líquido plana ». Universidade de São Paulo, 2018. http://www.teses.usp.br/teses/disponiveis/3/3133/tde-03052018-090007/.

Texte intégral

Résumé :

A macrossegregação pode causar problemas sérios em processos de fundição, mas pode ser útil em processos de refino metalúrgico como os empregados na produção de silício de alta pureza. Ela é formada por fluxos convectivos presentes tanto na solidificação plana quanto na solidificação com zona pastosa, enquanto o transporte difusivo é efetivo quando a solidificação direcional é controlada, mantendo-se uma interface plana. A modelagem da solidificação de lingotes em escala macroscópica é atualmente dividida em modelos que assumem a presença de uma zona pastosa e modelos que assumem interface plana como hipótese inicial, exigindo conhecimento prévio da morfologia interfacial durante toda a operação. Um modelo matemático para a macrossegregação causada por transportes difusivos e convectivos de soluto durante a solidificação com crescimento plano ou com zona pastosa foi apresentado e implantado. Uma análise numérica apenas do transporte difusivo revelou a transição da interface plana para uma zona pastosa desenvolvida, que ocorreu em coincidência com critérios de estabilidade clássicos, além de revelar uma região inicial refinada formada mesmo após a formação da zona pastosa e confirmar a ineficiência da difusão sozinha na formação de macrossegregação em maiores velocidades. A convecção demonstrou efeito estabilizador para a interface sólido-líquido plana ao reduzir a camada super-resfriada por soluto, assim como acentuou a macrossegregação, com tendência ao caso de Scheil. Ensaios experimentais para silício presentes na literatura foram avaliados com o modelo proposto, confirmando o efeito estabilizador da interface plana observado e também mostrando o papel fundamental da difusão na formação da interface plana. Os resultados do modelo foram comparados com os de ensaios experimentais conduzidos em um forno do tipo Bridgman com liga Al-1% Cu com velocidades de solidificação crescentes e a estabilidade da interface plana e a macrossegregação correspondente examinadas sem ou com convecção forçada. Os resultados experimentais indicaram uma região com interface sólido-líquido plana que, após a segunda mudança de velocidade, indicou a aparente formação de células, verificadas por análise metalográfica. A velocidade de crescimento crítica foi estimada no experimento, mostrando-se significativamente maior que a calculada através do critério do super-resfriamento constitucional.
Macrosegregation is a source of serious problems in castings, but it can be a useful tool in metallurgical refining processes such as those employed in the production of high-purity silicon. It is often a result of convective liquid flow either at planar solidification or when a mushy zone is present, while diffusive solute transport is effective at controlled directional solidification with planar interfaces. Ingot solidification modeling at macroscopic scale is currently divided in models assuming a mushy zone is always present and planar interfaceassuming models, thus requiring prior knowledge of interface morphology. A mathematical model for macrosegregation resulting from diffusion and convection during solidification with planar interface or mushy zone was presented and implemented. Diffusive transport was evaluated numerically, revealing a transition from planar to mushy-zone solidification conforming to classical stability criterions, with an initial refined zone that grew even after a mushy zone developed and the inefficacy of macrodiffusion-induced macrosegregation at higher growth velocities shown. Convection showed stabilizing effect for planar solid-liquid interface by reducing the solute-undercooled layer and increased macrosegregation, with a tendency towards Scheil model. Silicon experiments publicly available were compared with the present model, confirming the experimentally-observed stabilizing effect and proving the key role of diffusion at macrosegregation formation on these systems. The model was evaluated with experiments made in a Bridgman-type furnace with an Al-1% Cu alloy with increasing growth velocities to study interface stability and macrosegregation with or without liquid stirring. Results indicate a planar growth region followed by a cellular interface one after the second velocity change, as identified by metallographical testing. Critical growth velocities for classical criterions were estimated after the experiments and were smaller than the evaluated ones.

Styles APA, Harvard, Vancouver, ISO, etc.

20

Guerreiro, Duarte Nuno Tomé. « Os presos em Évora durante o liberalismo : realidade e representações sociais ». Master's thesis, Universidade de Évora, 2011. http://hdl.handle.net/10174/15223.

Texte intégral

Résumé :

Com este trabalho pretendemos apresentar um pequeníssimo contributo para a História da Prisão e da criminalidade na cidade de Évora, no período compreendido entre 1855 e 1875. O nosso principal objectivo é o de aferir se as novas preocupações filantrópicas e humanitaristas, fruto do ideário Liberal, tiveram efectivas repercussões no interior do espaço prisional eborense. Pretendemos também compreender a dinâmica do crime na mesma cidade, através da análise do percurso criminal de alguns dos presos na cadeia de Évora. Num âmbito mais geral propomo-nos compreender o enquadramento político e ideológico do Liberalismo que alicerçou as bases do novo paradigma penitenciário. Para atingirmos estes propósitos procederemos a uma breve contextualização da realidade socioeconómica e demográfica da região de Évora durante o período supracitado, bem como das condições físicas da Cadeia Civil de Évora, servindo-nos, neste caso, da correspondência e outra documentação produzida pelas autoridades locais e centrais, para além da imprensa regional. A caracterização sócio-demográfica dos detidos e a análise dos crimes que lhes eram imputados são os dois últimos tópicos que desenvolveremos neste estudo. Como conclusão geral, verificamos que a realidade penitenciária, apesar das preocupações das autoridades, não sofreu alterações substanciais, persistindo as más condições do cárcere eborense. No que respeita aos reclusos, na sua maioria eram homens, solteiros, até aos 30 anos de idade e trabalhadores de ocupação, oriundos maioritariamente do distrito de Évora. Neste período, os crimes pelos quais se registaram mais acusações foram os contra a propriedade, seguidos dos contra a ordem pública e dos crimes violentos; ABSTRACT: With this thesis, we intend to present a small contribution to the Prison’s History and to crime in Evora, between 1855 and 1875. Our main goal is to check if the philanthropist and humanitarian concerns, product of the liberal ideology, had effective repercussions in the interior of Evora’s prisonal space. We also seek to understand crime dynamics in this city, through the analysis of the crime course of some of the prisoners in Evora’s jail. In a more general sense, we propose to understand the political and ideological context of Liberalism, which planted the basis of the new penitentiary paradigm. To obtain these purposes we’ll proceed to a brief contextualization of the social economical and demographic reality of the region of Evora, during the above mentioned period of time, as well as of physical conditions of the Civil Prison of the city, using, therefore, letter-writing and other documents produced by local and central authorities, in addition to regional press. Social demographic characterization of the detained and the analysis of the crimes imputed to them are the last two topics that will be developed in this study. As a conclusion, we verified that the penitentiary reality, despite the authorities concerns, hasn’t suffered substantial changes, persisting the poor conditions of the prison. As for the prisoners, they were mostly single, up to 30s, occupational working men, mainly natives from the district. In this period, the most charged crimes were the ones against property, followed by the ones against public order and violent crimes.

Styles APA, Harvard, Vancouver, ISO, etc.

21

Fraiha, Marcos. « Efeitos da temperatura, pressão e taxa de cisalhamento sobre a viabilidade de esporo termodurico durante a extrusão de alimentos para animais ». [s.n.], 2008. http://repositorio.unicamp.br/jspui/handle/REPOSIP/257002.

Texte intégral

Résumé :

Orientadores: João Domingos Biagi, Antonio Carlos de Oliveira Ferraz
Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia Agricola
Made available in DSpace on 2018-08-12T05:33:01Z (GMT). No. of bitstreams: 1 Fraiha_Marcos_D.pdf: 1875565 bytes, checksum: a372a466eacf5e49b82f4cdc2d006270 (MD5) Previous issue date: 2008
Resumo: O objetivo geral deste trabalho foi determinar os efeitos da taxa de cisalhamento, temperatura e pressão gerados no processo de extrusão de alimentos para animais sobre a viabilidade de esporos bacterianos. Baseado na fundamentação teórica de reologia de materiais, foi possível a construção de um reômetro fundamental utilizando materiais e operações simples de tornearia. Para caracterizar o comportamento reológico de alimentos para animais, uma mistura de grãos de milho e soja na proporção 70:30 (massa:massa) foi submetida ao reômetro capilar sob 3 níveis de temperatura e umidade da massa, e 4 taxas de cisalhamento aparente: 80, 120 e 160°C, 26,5±0,08; 30,4±0,31 e 33,4±0,05%; 30,4; 72,9; 304,3 e 728,6 s-1 respectivamente. Diferentes taxas de deformação e dimensões da matriz foram utilizadas para obtenção das taxas de cisalhamento acima. Os efeitos de umidade e temperatura da massa, e taxa de cisalhamento sobre a mistura de milho e soja foram ajustados para uma expressão única (P<0.001, R2 = 0.93): ?=18.769,7 (?) -0,86 e (-9,34U+935T), onde (?) é a taxa de cisalhamento, U é a teor de água na amostra e T é o inverso da temperatura na massa, em escala Kelvin. Como esperado, a mistura moída de milho e soja apresentou comportamento pseudoplástico. Outro experimento objetivou determinar os parâmetros de destruição térmica de esporos de Bacillus sterothermophilus ATCC 7953 e a estimativa de suas dimensões. Os valores de D121,1°C e z para os esporos suspensos em solução salina foram 8,8 min e 12,8 °C, respectivamente. Para aqueles suspensos em mistura milho e soja, D121,1°C e z foram 14,2 min e 23,7 °C , respectivamente. As micrografias indicaram que os esporos apresentam-se como bastonetes, homogêneos em forma e dimensão, cujos comprimento e diâmetro foram estimados em 2 e 1 µm, respectivamente. Outro experimento visou determinar o efeito da taxa de cisalhamento sobre a viabilidade de esporos de B. stearothermophilus sob escoamento viscométrico em reômetro capilar. Os esporos foram inoculados em mistura de milho e soja para contagem e umidade de 106 UFC/5g, e 30,0±0,30%, respectivamente. As amostras foram submetidas às taxas de cisalhamento aparentes variando de 728,6 a 3.643,0 s-1, sob 80°C. As contagens microbiológicas foram menores quando comparadas ao controle (P < 0,001). Baseados nos parâmetros termobacteriológicos dos esporos, a redução de viabilidade observada não pode ser explicada pelo efeito do calor isoladamente, e confirma a hipótese do efeito do fenômeno mecânico sobre a redução celular. Outro trabalho visou determinar o efeito do calor, pressão e taxa de cisalhamento sobre a viabilidade de esporos termodúricos em ração animal submetida ao processo de extrusão. Os esporos foram semeados em mistura de grãos moídos de milho e soja, para contagem final de 106 UFC/5g e umidade de 30%, e submetidos ao processo em extrusora de rosca simples. A pressão estática não influenciou a viabilidade, porém temperatura e tensão cisalhante reduziram a viabilidade dos microorganismos. O percentual da redução da viabilidade dos microorganismos está diretamente relacionado ao volume de material submetido ao gradiente de velocidade de escoamento.
Abstract: The overall objective of this thesis was to determine the effects of mass temperature, pressure and shear rate on the viability of bacterial spores. The first paper describes the design and construction of a capillary rheometer attached to an universal testing machine used to characterize feed ingredients. To characterize the rheological behavior of animal feed under viscometric flow, a 70:30 (mass:mass) mixture of ground corn and soybean grains was submitted to a capillary rheometer at 3 temperatures and moisture levels, and 4 shear rates: 80, 120 and 160 °C, 26.5±0.08; 30.4±0.31 and 33.4±0.05%; 30.4; 72.9; 304.3 and 728.6 s-1 respectively. Based on experimental data, moisture content, mass temperature and shear rate effects on apparent shear viscosity of corn-soy mix were fitted to a single expression (P<0.001, R2 = 0.93): ?=18.769,7 (?) -0,86 e (-9,34U+935T), where (?) is the shear rate, U is the sample moisture and T is the sample reciprocal temperature in Kelvin scale. In order to determine thermobacteriological parameters for B. stearothermophilus spores, they were suspended in saline solution medium (0,85%, pH 6,7) and in ground corn-soy mix to a final count of 106 CFU/mL and 106 CFU/5g, respectively, distributed to TDT tubes and submitted to heat, from 100 to 126 °C, for a period of time varying from 0 to 40 min. D121,1°C and z values for these spores, as determined in the saline solution, were 8.8 min and 12.8 °C, respectively. D121,1°C and z values determined in the corn-soy mix were 14.2 min and 23.7 °C, respectively. The micrographs indicated that the spores are homogeneous in shape and size, which length and diameters are 2 and 1 µm, respectively. Another experiment aimed to determine shear effects on the viability of bacterial spores under viscometric flow. The spores were inoculated in the feed mixture to a final count of 106 CFU/5g, and 30.0±0.30% moisture. Samples were submitted to apparent shear rates varying from 728.6 to 3,643.0 s-1 at 80 °C in a capillary rheometer. Microbial counts were lower after treatments compared to control (P<0.001). A final work determined the heat, pressure and shear rate effects on the viability of the spores sowed into feed, submitted to extrusion. Bacillus stearothermophilus spores were sowed into corn and soy grain mixture to 106 CFU/5g and moisture of 30%, and then submitted to the extrusion process in a single screw extruder. Static pressure had no effect, but heat and shear stress reduced microbial count. The higher shear rate due to rotational speed increase of screw did not affect cell viability. It was concluded that static pressure level did not affect the viability of Bacillus stearothermophilus spores but heat and shear stress did. These conclusions indicated that the volume of feed under a velocity gradient during mass flow through the screw channel remained unchanged in the last case, what resulted in the same percentage of spores submitted to shear stress.
Doutorado
Tecnologia Pós-Colheita
Doutor em Engenharia Agrícola

Styles APA, Harvard, Vancouver, ISO, etc.

22

Basheer, P. A. M. « Durable structures with the application of innovative in situ tests, sensor systems and material technologies ». Thesis, Queen's University Belfast, 2014. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.669548.

Texte intégral

Résumé :

This thesis contains a selection of Author's publications describing developments in testing and monitoring of structural materials and their applications for assessing the durability in different environmental conditions. In compiling this volume the Author has given emphasis to four general research themes, viz. (i) Innovative in situ tests and sensor systems; (ii) Assessment of the durability enhancing materials and technologies; (iii) Investigation ot materials for manufacturing sustainable structures; and (iv) Specifi6ation and design of concretes for durability and expected service life. The work reported in this thesis was carried out during the Author's employment at Queen's University Belfast since his PhD graduation in July 1991 at the same University. The basic philosophy of his research that formed the backbone of publications included in this thesis was conceived and developed during his PhD project, as indicated in the first publication included in the thesis. All other publications deal with research carried out since then by the author either as a sole investigator or as a conjoint investigator, with the support of his research students and/or research assistants. The work was funded (with grant income in excess of £10.7 million) by the UK Engineering and Physical Sciences Research Council (EPSRC), Department of Environment, Technology Strategy Board, Invest Northern Ireland, European Commission, the Carbon Trust, the Australian Research Council and various regional, national and international industries. Although there have been many technology transfer and dissemination activities to facilitate appropriate research impact of all the projects, the Author would highlight that all the four research themes considered in this thesis are still relevant for further research in the field of durable and sustainable structures.

Styles APA, Harvard, Vancouver, ISO, etc.

23

Galvão, Adriana Lages. « Fragilização em aço 300M durante tratamento térmico de revenido ». Instituto Tecnológico de Aeronáutica, 1992. http://www.bd.bibl.ita.br/tde_busca/arquivo.php?codArquivo=1793.

Texte intégral

Résumé :

No presente trabalho utilizou-se o aço 300M, a fim de constatar os processos de fragilização (da martensita revenida e ao revenido), quando o mesmo é exposto a certas faixas de temperatura. Para isto, o material foi submetido a duas condições diferentes de tratamento térmico: temperado e revenido (40 min a 350C) e temperado, revenido (40 min a 600C) e envelhecido (18 h a 430C). Após serem tratados térmicamente foram feitos ensaios Charpy nas temperaturas: -196C, -100C, -50C, -150C, -220C. Estes ensaios tiveram como objetivo o levantamento de curvas de transição dúctil/frágil. Foram observadas as superfícies de fratura das amostras ensaiadas no MEV, a fim de determinar os mecanismos de propagação e iniciação de fratura. Além disso, amostras polidas e atacadas também foram observadas para caracterizar as microestruturas obtidas com maior detalhe. O revenimento em 350C não causou uma FMR (fragilização da martensita revenida) sensível, podendo ser justificada pela transformação dos carbonetos E em cementita ter sido apenas parcial no 300M. O revenimento em 600C e envelhecimento posterior causou fragilização no material, parecendo indicar que foi causada pela presença conjunta de segregação de fósforo e precipitação de carbonetos nos contornos de grão pré-austeníticos.

Styles APA, Harvard, Vancouver, ISO, etc.

24

Gomar, Peiró Salvador. « Emisión de compuestos de flúor durante la cocción de baldosas cerámicas ». Doctoral thesis, Universitat Jaume I, 2016. http://hdl.handle.net/10803/404211.

Texte intégral

Résumé :

El trabajo profundiza en el conocimiento científico relativo a la emisión de contaminantes ácidos de naturaleza gaseosa que tiene lugar durante el tratamiento térmico de baldosas cerámicas. Se ha prestado especial atención a los compuestos de flúor por sus implicaciones ambientales y porque son considerados como los contaminantes característicos de la industria cerámica. Una parte muy importante del trabajo desarrollado se ha llevado a cabo a nivel industrial sobre hornos continuos de cocción rápida, monoestrato, y que utilizan como combustible gas natural.
This study has focussed on the emission of acidic pollutants of a gaseous nature that takes place during the heat treatment of ceramic tiles. Attention has been paid to fluorine compounds because of their environmental implications and because they are considered as the characteristic pollutants of the ceramic industry. A very important part of the work has been carried out at the industrial level on continuous fast-cycle combustion kilns (roller kilns) fuelled by natural gas.

Styles APA, Harvard, Vancouver, ISO, etc.

25

Maia, Newton Alves. « Método ultrassônico para avaliação da viscosidade e do coeficiente de compressibilidade durante o processo de cura de resinas ». Universidade do Estado do Rio de Janeiro, 2010. http://www.bdtd.uerj.br/tde_busca/arquivo.php?codArquivo=1312.

Texte intégral

Résumé :

Durante a cura, ou seja, durante o processo de reticulação, resinas sofrem alterações irreversíveis em suas propriedades químicas e físicas, como, por exemplo, alterações significativas em seu coeficiente de compressibilidade (inverso do módulo de compressão volumétrico) e em sua viscosidade. A variação destas propriedades, ao longo de uma dimensão (direção) no interior de uma resina em processo de cura, pode ser obtida a partir de técnicas ultrassônicas baseadas no princípio pulso-eco, que permite a estimativa da velocidade de propagação e das atenuações das ondas. Antes da cura, as resinas apresentam velocidades de propagação entre 1600 e 1800 m/s, com viscosidade e atenuação pequenas. Durante o processo de cura ocorre um aumento notável da viscosidade, que causa grandes atenuações na onda ultrassônica. Chegando ao final do processo de cura, tanto a atenuação quanto a viscosidade voltam a diminuir. Após a reticulação, a velocidade de propagação pode ser superior a 2500 m/s. Visto que a densidade varia pouco durante a cura, a alteração de velocidade, observada durante a cura, pode ser atribuída às mudanças no módulo de compressão volumétrico da resina. O método pulso-eco descrito nesta dissertação permite monitorar, de forma não invasiva, a variação da viscosidade e a variação do coeficiente de compressibilidade durante o tempo de cura de uma resina epóxi, ao longo da direção de propagação de uma onda ultrassônica.
During the curing process, i.e. crosslinking process, resins suffer significant and irreversible changes on theirs chemical and physical properties, as the alterations in the compressibility coefficient (the inverse of bulk modulus) and in the viscosity. The changes in these properties along a direction inside of a resin, under a curing process, can be estimated with techniques based on pulse-echo ultrasonic waves. With these techniques is possible to obtain the ultrasonic wave speed and the attenuation imposed on the wave by a resin under curing. Before the cure, resins have speeds of wave propagation between 1600 and 1800 m/s, low attenuation and low viscosity. As the curing process evolves, there is a remarkable increase of viscosity, which causes great attenuations. After that, and until the end of the curing process, the viscosity and the attenuation decrease. After the cure and solidification, the wave speed may reach values up to 2500 m/s. Since the density almost does not vary during the cure, the changes in wave speed can be attributed to changes in the resins bulk modulus. The pulse-echo method, described in this dissertation, allows the monitoring, in a no invasive way, of the variation of the bulk modulus and the changes in viscosity along a direction of propagation of an ultrasonic wave, during the curing process of an epoxy resin.

Styles APA, Harvard, Vancouver, ISO, etc.

26

Quandt, Mirian. « Formação de amônia durante o processo de nitretação por plasma ». Florianópolis, SC, 2002. http://repositorio.ufsc.br/xmlui/handle/123456789/83161.

Texte intégral

Résumé :

Dissertação (mestrado) - Universidade Federal de Santa Catarina, Centro Tecnológico. Programa de Pós-Graduação em Ciência e Engenharia dos Materiais.
Made available in DSpace on 2012-10-19T21:28:52Z (GMT). No. of bitstreams: 1 189799.pdf: 2299615 bytes, checksum: 3613a549f36637223f6b44ba31c08489 (MD5)

Styles APA, Harvard, Vancouver, ISO, etc.

27

DESIDERI, AGNESE. « I processi di categorizzazione sociale durante l'infanzia ». Doctoral thesis, Università Cattolica del Sacro Cuore, 2022. http://hdl.handle.net/10280/114596.

Texte intégral

Résumé :

Questa tesi affronta il tema dei processi di categorizzazione sociale durante l’infanzia. Suddetto tema ha suscitato ampio interesse in numerose discipline quali la pedagogia, l’antropologia, la psicologia. Per quanto riguarda la disciplina sociologica, nonostante il tema rappresenti dal punto di vista epistemologico un tema centrale per la disciplina, il campo empirico relativo all’infanzia rimane, soprattutto in Italia, ancora poco sondato. È stato quindi realizzato durante l'anno scolastico 2018-2019 uno studio empirico sperimentale nelle città di Firenze e di Prato. Il campione è costituito da 96 famiglie provenienti da tre istituti scolastici suddivisi in base al livello socio-economico: alto, medio e medio-basso (l’indicatore ESCS - Economic, Social and Cultural Status - è stato fornito dal Ministero dell’istruzione italiano). La metodologia utilizzata corrisponde ai mixed-methods: gli strumenti di intervista e di analisi non standard sono stati intersecati con strumenti di intervista e di analisi standard. Novantasei minori, di età pari a sette anni ed i loro genitori sono stati intervistati tramite intervista con foto-stimolo. É stato anche utilizzato un questionario al fine di ricostruire il profilo socio-demografico e socioeconomico delle famiglie. I foto-stimoli ritraggono individui realmente esistenti e sono stati selezionati sulla base dei seguenti criteri: genere, età, appartenenza socio-professionale, appartenenza etnica ed etno-religiosa (tenendo conto delle principali minoranze etniche, etno-religiose e dei principali gruppi socio-professionali presenti in Italia nel 2019). I risultati raggiunti ruotano attorno alle seguenti macro-tematiche: il ruolo del linguaggio di senso comune nell’uniformare le risposte dei soggetti intervistati; il ruolo giocato dalla cultura materiale nella fase di “giustificazione” delle modalità di impiego delle categorie sociali. Ed infine, il tema della “riproduzione sociale” dell’habitus materno (quindi la coincidenza – elevata - nell'utilizzo delle stesse categorie sociali da parte delle madri e dei rispettivi figli).
This thesis deals with the processes of social categorization during childhood. This topic has aroused wide interest in many disciplines such as pedagogy, anthropology, psychology. As for sociology, although the topic represents a central theme for the discipline from an epistemological point of view, there is still a lack of empirical research on childhood, especially in Italy. Therefore, an empirical, experimental study has been carried out during the academic year 2018-2019 in the cities of Florence and Prato. The sample includes about 96 families from three schools. The schools are divided into three socio-economic levels: upper, middle and lower-middle, according to the ESCS (Economic, Social and Cultural Status indicator has been provided by the Italian Ministry of Education). The study employs a mixed methods approach. Children, aged seven, as well as their parents have been interviewed using photo-elicitation interview. A survey has been also used to question children’s families in order to reconstruct their socio-demographic and socio-economic profile. The images show real people that differ in gender, age, ethnicity, religious background, as well as in socio-economic and socio-professional characteristics (taking into account the main ethnic, ethno-religious minorities and the main socio-professional groups present in Italy in 2019). The results achieved revolve around the following macro-themes: the role played by the common sense language in standardizing the respondents's answers; the role played by the material culture when the respondents try to justify «how they use social categories". And finally, the theme of "social reproduction" of the maternal habitus (therefore the coincidence - high - in the use of the same social categories of mothers and their children).

Styles APA, Harvard, Vancouver, ISO, etc.

28

Cobos, Antonio. « Estudo da descarbonetação durante a sinterização por plasma de aço carbono ». Florianópolis, SC, 2003. http://repositorio.ufsc.br/xmlui/handle/123456789/84835.

Texte intégral

Résumé :

Dissertação (mestrado) - Universidade Federal de Santa Catarina, Centro Tecnológico. Programa de Pós-Graduação em Ciência e Engenharia de Materiais.
Made available in DSpace on 2012-10-20T12:56:36Z (GMT). No. of bitstreams: 1 196652.pdf: 5983693 bytes, checksum: 371f2a8370da53d4d3b1a2f3519d71a0 (MD5)

Styles APA, Harvard, Vancouver, ISO, etc.

29

Gómez, de Soler Bruno. « Procedencia del aprovisionamiento lítico durante el Paleolítico medio en el yacimiento del Abric Romaní (Capellades, Barcelona). Niveles M, Oa y P ». Doctoral thesis, Universitat Rovira i Virgili, 2016. http://hdl.handle.net/10803/461891.

Texte intégral

Résumé :

L'objectiu principal d'aquesta Tesi Doctoral és el coneixement de les matèries primeres d'origen abiòtic utilitzades pels neandertals que varen ocupar l'Abric Romaní durant els nivells M, Oa i P. La intenció és poder establir la procedència geogràfica del material arqueològic i així poder conèixer les àrees d'aprovisionament lític i, conseqüentment, les seves rutes de mobilitat. Com que la matèria primera més utilitzada, amb uns percentatges del 80%, és el sílex, ens centrarem en aquesta litologia per ser la més abundant i representativa del registre arqueològic. Pels tres nivells estudiats, el tipus silici més representatiu en el registre arqueològic és el de Sant Martí de Tous (SMT) que es situa a uns 15 km de distància de l'Abric Romaní. La ruta de mobilitat és unidireccional NW-SE, deixant de banda altres possibles rutes com la E-W, degut a l'absència en el registre arqueològic dels tipus silicis de la conca del Gaià ALE i SAL, o a les poques evidències de freqüentació del eix S-SE per la poca presència dels sílex tipus MUSCH i SER (Serralada prelitoral i Depressió litoral), que ens marcaria una possible direcció cap al mar. En definitiva, establim com model d'aprovisionament pels nivells estudiats de l'Abric Romaní (M, Oa i P), la captació regional en el que el radi de captació diari s'estableix sobre els 15km, on es localitzen les majors concentracions de silicificacions en el territori amb els afloraments de St. Martí de Tous (SMT), arribant en ocasions a la captació en un radi d'uns 25km pel sílex de la Panadella (PAN).
El objetivo principal de esta Tesis Doctoral es el conocimiento de las materias primas de origen abiótico utilizadas por los neandertales que ocuparon el Abric Romaní durante los niveles M, Oa y P. La intención es poder establecer la procedencia geográfica del material arqueológico y así poder conocer las áreas de aprovisionamiento lítico y por consiguiente sus rutas de movilidad. Como la materia prima más utilizada, con unos porcentajes en torno al 80%, es el sílex, nos centramos en esta litología por ser la más abundante y representativa del registro arqueológico. Para los tres niveles estudiados, el tipo silíceo más representado en el registro arqueológico es el de Sant Martí de Tous (SMT) que se sitúa a unos 15 km de distancia del Abric Romaní. La ruta de movilidad es unidireccional NW-SE, dejando de lado otras posibles rutas como la E-W, debido a la ausencia en el registro arqueológico de los tipos silíceos de la cuenca del Gaià ALE y SAL, o a las pocas evidencias de frecuentación del eje S-SW por la poca presencia de los sílex tipo MUSCH y SER (Cordillera prelitoral catalana y Depresión litoral), que nos marcaría una posible dirección hacia el mar. En definitiva, establecemos como modelo de aprovisionamiento para los niveles estudiados del Abric Romaní (M, Oa y P), la captación regional en el que el radio de forrajeo se establece sobre los 15 km, donde se localizan las mayores concentraciones de silicificaciones en el territorio con los afloramientos de St. Martí de Tous (SMT), llegando en ocasiones a aumentar hasta casi los 25 km con la captación del sílex de la Panadella (PAN).
The main objective of this thesis is the knowledge of abiotic raw materials used by the Neanderthals who occupied the Abric Romani in the M, Oa and P levels. Our objective is to establish the geographical origin of the archaeological material and thus to know lithic procurement areas and therefore their mobility routes. As the raw material used, with percentages around 80%, is chert, we focus in this lithology because is the most abundant and representative of the archaeological record. For the three levels studied, the more siliceous type represented in the archaeological record is that of Sant Martí de Tous (SMT) which is situated about 15 km away from the Abric Romani rockshelter. The mobility routes are unidirectional: NW-SE. The other possible routes, like as E-W, are ignored due to the absence in the archaeological record of the siliceous types ALE and SAL from the Gaià basin. In addition, there is little evidence of the axis S -SW by the low presence of MUSCH and SER chert types (littoral and littoral Catalan Cordillera Depression), which would mark us a possible direction towards the sea. Definitely, we establish a provisioning model as a regional catchment of a foraging range about 15 km, where the highest concentrations of silicifications are found in the St. Martí de Tous (SMT) outcrops, sometimes leading to increase to almost 25 km with the catchment in the Panadella (PAN) outcrops.

Styles APA, Harvard, Vancouver, ISO, etc.

30

Bernabé, Giseli Aparecida [UNESP]. « Extração e identificação de material lignocelulósico presente durante o processo de compostagem ». Universidade Estadual Paulista (UNESP), 2008. http://hdl.handle.net/11449/97739.

Texte intégral

Résumé :

Made available in DSpace on 2014-06-11T19:29:06Z (GMT). No. of bitstreams: 0 Previous issue date: 2008-01-23Bitstream added on 2014-06-13T20:59:09Z : No. of bitstreams: 1 bernabe_ga_me_araiq.pdf: 2071550 bytes, checksum: d5676cd432e05da0512c4d6640e26526 (MD5)
Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)
Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)
Neste trabalho foram estudados a extração e identificação de material lignocelulósico presente durante o processo de compostagem de Resíduos Sólidos Domiciliares (R.S.D). Amostras foram recolhidas em diferentes estágios de compostagem: cru (ou 0 dias), 15; 30; 60; 90 e 120 dias e realizadas suas respectivas extrações de lignina e celulose. Anteriormente à extração de lignina do composto, foi necessária a realização de duas extrações: aquosa e lipídica, a fim de que o máximo de substâncias solúveis e ácidos graxos fossem removidos previamente à extração de lignina, sendo que nesta, utilizou-se uma mistura de HCl/dioxano (9:1) para tal fim. Enquanto que para a extração de celulose do composto foi utilizada solução de NaOH ( hidróxido de sódio a 4%). Curvas de Calorimetria Exploratória Diferencial (DSC) foram obtidas paras as diversas amostras de composto; para celulose e lignina extraídas do mesmo, em diferentes períodos de compostagem. A caracterização de lignina do composto foi feita, também por diferentes técnicas: Termogravimetria (TG), Infravermelho (IV) e Ultravioleta (UV). Os resultados obtidos pelas curvas DSC do composto, lignina e celulose mostraram que os dois últimos estavam presentes do início ao final da compostagem. No entanto, seus perfis não eram mais de lignina e celulose, mas sim, de material tipo-lignina e tipo-celulose, já que estes sofreram decomposição, combinação ou transformação em suas estruturas durante todo o processo; o que pode ser evidenciado, principalmente para material tipo-lignina, com as análises de Infravermelho e Ultravioleta.
The extraction and identification of lignincellulosic material during the composting process of domiciliar solid residues (RSD) were studied in this work. Samples were collected in different composting steps: raw (or 0 days), 15, 30, 60, 90, and 120 days, lignins and cellulose extractions were performed. Previously to the compost´s lignin extraction, it was necessary aqueous and lipidic extractions so that the maximum of soluble substances and fatty acids were removed before lignin extraction. In this process was used HCl: dioxane (9:1) mixture, while to the compost´s cellulose extraction was used (4% NaOH solution). DSC curves were obtained to several compost samples; to cellulose and lignin extracted from the same compost in different composting periods. The lignin extracted from the compost was also analysed through several techniques: Thermogravimetry (TG), Infra Red (IR) and Ultraviolet (UV) spectrophotometry. The obtained results through DSC curves of compost, lignin and cellulose showed that the last two ones were presented from the beginning to the end of composting process. However their structures weren´t of lignin and cellulose anymore, but a material like-lignin and likecellulose, because they undergone decomposition, combination and transformation in their structures during all process, which could be evidencied, mainly to like-lignin material, with the IR and UV analyses.

Styles APA, Harvard, Vancouver, ISO, etc.

31

Bernabé, Giseli Aparecida. « Extração e identificação de material lignocelulósico presente durante o processo de compostagem / ». Araraquara : [s. n.], 2008. http://hdl.handle.net/11449/97739.

Texte intégral

Résumé :

Orientador: Clóvis Augusto Ribeiro
Banca: Eder Tadeu Gomes Cavalheiro
Banca: Eny Maria Vieira
Resumo: Neste trabalho foram estudados a extração e identificação de material lignocelulósico presente durante o processo de compostagem de Resíduos Sólidos Domiciliares (R.S.D). Amostras foram recolhidas em diferentes estágios de compostagem: cru (ou 0 dias), 15; 30; 60; 90 e 120 dias e realizadas suas respectivas extrações de lignina e celulose. Anteriormente à extração de lignina do composto, foi necessária a realização de duas extrações: aquosa e lipídica, a fim de que o máximo de substâncias solúveis e ácidos graxos fossem removidos previamente à extração de lignina, sendo que nesta, utilizou-se uma mistura de HCl/dioxano (9:1) para tal fim. Enquanto que para a extração de celulose do composto foi utilizada solução de NaOH ( hidróxido de sódio a 4%). Curvas de Calorimetria Exploratória Diferencial (DSC) foram obtidas paras as diversas amostras de composto; para celulose e lignina extraídas do mesmo, em diferentes períodos de compostagem. A caracterização de lignina do composto foi feita, também por diferentes técnicas: Termogravimetria (TG), Infravermelho (IV) e Ultravioleta (UV). Os resultados obtidos pelas curvas DSC do composto, lignina e celulose mostraram que os dois últimos estavam presentes do início ao final da compostagem. No entanto, seus perfis não eram mais de lignina e celulose, mas sim, de material tipo-lignina e tipo-celulose, já que estes sofreram decomposição, combinação ou transformação em suas estruturas durante todo o processo; o que pode ser evidenciado, principalmente para material tipo-lignina, com as análises de Infravermelho e Ultravioleta.
Abstract: The extraction and identification of lignincellulosic material during the composting process of domiciliar solid residues (RSD) were studied in this work. Samples were collected in different composting steps: raw (or 0 days), 15, 30, 60, 90, and 120 days, lignins and cellulose extractions were performed. Previously to the compost's lignin extraction, it was necessary aqueous and lipidic extractions so that the maximum of soluble substances and fatty acids were removed before lignin extraction. In this process was used HCl: dioxane (9:1) mixture, while to the compost's cellulose extraction was used (4% NaOH solution). DSC curves were obtained to several compost samples; to cellulose and lignin extracted from the same compost in different composting periods. The lignin extracted from the compost was also analysed through several techniques: Thermogravimetry (TG), Infra Red (IR) and Ultraviolet (UV) spectrophotometry. The obtained results through DSC curves of compost, lignin and cellulose showed that the last two ones were presented from the beginning to the end of composting process. However their structures weren't of lignin and cellulose anymore, but a material like-lignin and likecellulose, because they undergone decomposition, combination and transformation in their structures during all process, which could be evidencied, mainly to like-lignin material, with the IR and UV analyses.
Mestre

Styles APA, Harvard, Vancouver, ISO, etc.

32

Biasotto, Daniela Aparecida. « Estudo eletromiografico de musculos do sistema estomatognatico durante a mastigação de diferentes materiais ». [s.n.], 2000. http://repositorio.unicamp.br/jspui/handle/REPOSIP/288812.

Texte intégral

Résumé :

Orientador: Fausto Berzin
Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Odontologia de Piracicaba
Made available in DSpace on 2018-07-26T03:24:01Z (GMT). No. of bitstreams: 1 Biasotto_DanielaAparecida_M.pdf: 2842575 bytes, checksum: feb2616d252c3d3743c0889f8eeb8923 (MD5) Previous issue date: 2000
Resumo: O objetivo deste estudo foi comparar o comportamento de alguns dos principais músculos da mastigação (M. temporal, porção anterior, M. masséter e MM. suprahióideos), com a utilização de duas marcas comerciais de goma de mascar A e B e dois materiais insípidos, Rolinho de Algodão e Parafilm.M.@, através de análise dos sinais eletromiográficos. Participaram deste estudo dez (10) voluntários, do sexo feminino, adulto/jovem, com idade variando 18 a 27 anos, com normo oclusão, e sem história de disfunção craniomandibular. A atividade mastigatória foi realizada com o voluntário sentado com o plano de Frankfurt posicionado paralelo ao solo. Para tanto, foram realizados exames eletromiográficos dos mm. temporais, porção anterior e masséteres, bilaterais e supra-hióideos, bilateralmente; utilizando-se mini eletrodos passivos de superfície. Os voluntários foram orientados a mastigar bilateral e simultaneamente cada um dos produtos, em seqüência aleatória. Para o estudo da atividade mastigatória os traçados eletromiográficos foram tratados através de retificação, envoltório linear e normalização, de forma que o coeficiente de variação resultante do processamento fosse analisada comparativamente. Todos os dados foram tratados pela Análise de Variância Univariada e Multivariada. Os resultados do estudo demostrou que não existiu diferença estatística fortemente significativa entre o material Rolinho de Algodão e Parafilm. Estes produtos revelam que no contexto geral ambos são indicados para execução do exame eletromiográfico, pois apresenta menor variação com relação aos demais produtos
Abstract: The purpose of this study was to investigate and to compare the behavior of the chewing muscles (M.Temporales, anterior portion, M.Masseter and M.Suprahyoid), through the use to two chewing gums commercial A and B and two insipid product, Cotton Sal! and Parafilm.M.@, with the objective of analysis of the electromyographyc trace. A total of 10 young adults subjects, of the female sex, with an age ranger from 18 to 27 years, with normal Angle's class I occlusion assessed by intra-oral examination. No signs or symptoms of stomatognathic dysfunctions or other general disease affecting the neuromuscular system were presented. The chewing activity was accomplished with subjects were confortably seat in straight-backed chairs with head unsupported and positioned so that the Frankfort plane was parallel to the floor. For this EMG took place, using bipolar electrodes surface, positioned on the anterior temporal, masseter, bilateral!y, and suprahyod muscles. The subjectives were guided to chew bilaterally and simultaneously each one of the products, in aleatory sequence. For study for the masticatory activity were the electromyographyc signals were processed by fullwave rectification, linear enveloped and normalisation, so that the coefficient of variation (CV%) of chewing activity. The statistic method used was the data based on by the Analysis of Variation. The results of this research demonstrated that didn't exist statistical significant difference between the Cotton Sal! And Parafilm.M.@
Mestrado
Anatomia
Mestre em Biologia e Patologia Buco-Dental

Styles APA, Harvard, Vancouver, ISO, etc.

33

Melo, Mirian de Lourdes Noronha Motta. « Analise numerica da variação da permeabilidade de canais interdentriticas durante a solidificação de ligas metalicas ». [s.n.], 1991. http://repositorio.unicamp.br/jspui/handle/REPOSIP/265132.

Texte intégral

Résumé :

Orientador: Rezende Gomes dos Santos
Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Mecanica
Made available in DSpace on 2018-07-14T01:23:02Z (GMT). No. of bitstreams: 1 Melo_MiriandeLourdesNoronhaMotta_M.pdf: 2852437 bytes, checksum: 011d1bdb976adbacceeba6b0886afabf (MD5) Previous issue date: 1991
Resumo: Este trabalho apresenta o desenvolvimento de um modelo numérico , baseado em diferenças finitas, determinação dos principais parâmetros térmicos e que permite a estruturais processo de solidificação de ligas metálicas, para casos do de fluxos de esfera). calor unidirecional (placa) e radiais o modelo (cilindro permite e Utilizando tais parâmetros a determinação da tortuosidade e da permeabilidade os canais interdendriticos que são importantes para a análise da formação de microporosidades durante o processo de solidificação O modelo desenvolvido é aplicado para o estudo da solidificação de diferentes ligas em diversas condições do sistema metal/molde
Abstract: In this work a numerical method, using finite difference equations , is proposed to study the solidification of metallic alloys under unidirectional (slabs) and radial (cylinders and spheres) heat flux. The method is able to predict the tortosity and permeability of the dendritic channels , which are important to study pore formation during solidification. The method is aplied to study different alloys and different metal/mold conditions
Mestrado
Mestre em Engenharia Mecânica

Styles APA, Harvard, Vancouver, ISO, etc.

34

Roy, Sunyer Miquel. « Materias primas líticas y su explotación durante la prehistoria en el prepirineo oriental (NE de Iberia) ». Doctoral thesis, Universitat Autònoma de Barcelona, 2016. http://hdl.handle.net/10803/400712.

Texte intégral

Résumé :

Los yacimientos arqueológicos registran claves para reconstruir las formas de vida de nuestros antepasados. En el Prepirineo ilerdense, los vestigios de ocupaciones prehistóricas hallados en los últimos años posibilitan analizar esta cuestión en un registro de referencia en Europa occidental. El estudio desde una perspectiva geológica de los recursos de materias primas líticas de esta región permite analizar la gestión de los recursos líticos por los grupos humanos durante el Pleistoceno superior final. La finalidad de este estudio es identificar la disponibilidad de rocas potencialmente utilizables por sociedades cazadoras-recolectoras en el área del Prepirineo ilerdense; aportación que servirá como base para analizar cuestiones relacionadas con la gestión de materias primas líticas en los yacimientos regionales. Los resultados se aplican al análisis de dos yacimientos: Roca dels Bous y Cova Gran de Santa Linya. El estudio regional se ha focalizado en dos tipos de afloramientos: afloramientos primarios y secundarios, separación que se debe a diferencias metodológicas e interpretativas sustanciales. Este análisis genera indicadores sobre la capacidad de explotar estos recursos por nuestros antepasados, determinándose que la región posee una relativa abundancia de rocas aptas para la talla y de distribución geográfica heterogénea, delimitando áreas de captación relativamente restringidas. Se contabilizan cuatro recursos potenciales: tres en posición primaria (calcedonia garumniense, sílex de la Serra Llarga y sílex de Tartareu) y uno en posición secundaria (terrazas fluviales cuaternarias), que poseen rasgos petrológicos suficientemente diferenciados como para identificarlos en contextos arqueológicos. El análisis en Roca dels Bous y Cova Gran ha sido posible gracias al diseño e implementación de metodologías sistemáticas que aportan innovaciones en el campo tratado. Se han generado indicadores para comprender los sistemas de aprovisionamiento y gestión de las rocas durante el Paleolítico Medio final y Paleolítico Superior antiguo en trece conjuntos arqueológicos. Se ha determinado que estas series se componen mayoritariamente por tres recursos líticos analizados en la primera parte (calcedonia, sílex de la Serra Llarga y depósitos fluviales), observando variaciones significativas de derivan de constricciones medioambientales, técnicas y culturales. Las dominancia de litologías de los depósitos fluviales en Roca dels Bous refleja patrones de selección en busca de cualidades concretas que se interpreta como un indicador del conocimiento del paisaje por los neandertales. La aparición de materiales regionales en este yacimiento sugiere pautas de movilidad estacional entre Prepirineo y Depresión del Ebro, registrándose variaciones entre las cuatro series de esta secuencia que indican la variabilidad de estrategias adaptativas de esos neandertales. En Cova Gran, se observa un uso mayoritario de materias primas locales y regionales, aunque se detectan fluctuaciones significativas entre los dos períodos crono-culturales de la secuencia (Paleolítico Medio - Paleolítico Superior) representadas por la aportación significativa de rocas metamórficas en los niveles de Paleolítico Medio y el uso exclusivo de calcedonia y sílex en los niveles de Paleolítico Superior antiguo. Estos datos ayudan a caracterizar la transición Paleolítico Medio-Paleolítico Superior asociada al reemplazamiento de las poblaciones neandertales por humanos modernos. Las causas de estos cambios parecen estar relacionadas con modificaciones en los métodos de talla laminar introducidos a partir del Paleolítico Superior, que requieren de materias primas específicas. La gestión de recursos líticos centrada en el Prepirineo ilerdense y el norte de la Depresión del Ebro se complementa con el hallazgo testimonial de piezas que parecen tener su procedencia en formaciones alejadas. En concreto se han identificado marcadores que conectan con áreas como el centro de la Depresión del Ebro (área de los Monegros) así como con la vertiente norte de los Pirineos, una noción hasta ahora no planteada en la región del noreste peninsular en cronologías de Paleolítico Medio y Paleolítico Superior antiguo.
Archaeological sites record the evidences to reconstruct the life forms of our prehistoric ancestors. In the eastern Pre-Pyrenees, the remains of human occupations found during the last years allow us to address this subject in an exceptional context within Western Europe. The analysis of lithic raw material sources in this area from a geological perspective allows us to characterize the management of lithic resources by human groups in the Late Upper Pleistocene. The aim of this study is to identify the different raw material sources that were potentially available for hunter-gatherer societies in a region of the Pre-Pyrenees. This approach will provide a geological basis from which to perform detailed lithic raw material studies in archaeological sites in the future. Results of this study are applied to the analysis of two outstanding archaeological sites of this region: Roca dels Bous and Cova Gran de Santa Linya. The regional study has focused in the analysis two types of deposits: primary and secondary deposits (fluvial terraces), a strategy that follows the methodological and interpretative particularities of each kind of outcrop. This analysis generates insights about the capacity of exploiting the different lithic resources by our ancestors, establishing that the region shows a relative high abundance and variability of knappable rocks following a heterogeneous geographical distribution; a configuration that permits to define discrete catchment areas. Four main resources have been distinguished: three in primary position (garumnian chalcedony, Serra Llarga flint and Tartareu flint) and one in secondary position (quaternary fluvial terraces), which present distinctive petrological features that can be identified in archaeological contexts. The analysis of Roca dels Bous and Cova Gran sites has been performed after a systematic methodological design that provides several innovations in this area of study. Insights about procurement systems and lithic resource management during the Late Middle Paleolithic and Early Upper Paleolithic have been generated in thirteen archaeological levels. These series are composed by three main lithic raw materials that were analyzed in the previous regional study (chalcedony, Serra Llarga flint and quartzite), revealing significant variations that are the result of environmental, technical and cultural constrictions. The relevance of rocks from the fluvial deposits in Roca dels Bous shows selection patterns seeking for specific qualities of quartzites, a pattern that is interpreted as an indicator of the profound knowledge of the landscape by Neanderthals. In Cova Gran, a predominance of local and regional raw materials has been observed, although significant fluctuations among the two major chrono-cultural periods (Late Middle Paleolithic – Early Upper Paleolithic) have been detected, represented by the recurrent exploitation of fluvial deposits in the mousterian layers, while in the Upper Paleolithic the only resources exploited were chalcedony and flint. These data contribute in the characterization of the Middle-to-Upper Paleolithic transition linked with the replacement of Neanderthals by Modern Humans in Western Europe. The reasons for these changes seem to be related with modifications in knapping methods introduced since the Upper Paleolithic; methods that require specific raw materials. Altogether, both sites show lithic procurement systems centered around the Pre-Pyrenees and the northern part of the Ebro Depression, although testimonial findings seem to point at the exploitation of more remote areas. Long distance markers have been detected that connect both sites with the central part of Ebro Depression (Monegros area) as well as the northern slopes of the Pyrenees, a fact not identified until now in northeastern Iberia during Middle and Early Upper Paleolithic periods.

Styles APA, Harvard, Vancouver, ISO, etc.

35

Freitas, Lucimara Rodrigues de. « A segurança de produtos para saúde processados durante o transporte e armazenamento em unidades de internação ». Universidade Federal de Goiás, 2013. http://repositorio.bc.ufg.br/tede/handle/tede/3753.

Texte intégral

Résumé :

Submitted by Marlene Santos (marlene.bc.ufg@gmail.com) on 2014-12-04T19:58:46Z No. of bitstreams: 2 Dissertação - Lucimara Rodrigues de Freitas - 2013.pdf: 1562277 bytes, checksum: 978562bdab7096ef50f9cc0ebdf51219 (MD5) license_rdf: 23148 bytes, checksum: 9da0b6dfac957114c6a7714714b86306 (MD5)
Approved for entry into archive by Cláudia Bueno (claudiamoura18@gmail.com) on 2014-12-05T14:19:09Z (GMT) No. of bitstreams: 2 Dissertação - Lucimara Rodrigues de Freitas - 2013.pdf: 1562277 bytes, checksum: 978562bdab7096ef50f9cc0ebdf51219 (MD5) license_rdf: 23148 bytes, checksum: 9da0b6dfac957114c6a7714714b86306 (MD5)
Made available in DSpace on 2014-12-05T14:19:09Z (GMT). No. of bitstreams: 2 Dissertação - Lucimara Rodrigues de Freitas - 2013.pdf: 1562277 bytes, checksum: 978562bdab7096ef50f9cc0ebdf51219 (MD5) license_rdf: 23148 bytes, checksum: 9da0b6dfac957114c6a7714714b86306 (MD5) Previous issue date: 2013-04-29
This exploratory, cross-sectional descriptive and quantitativestudy was performed in 11 inpatient units of a large public teaching hospital in the city of Goiânia, Goias, Brazil. The general objective was to assess the safety of processed patient care equipment during transportand storage in inpatient units, and the specific objective was to identify those responsible for the equipment after processing and distribution to inpatient units, identify structural features and material resources available for transportation and storage of equipment in inpatient units, describe the handling of the equipment by the healthcare team with regard to the transportation of and storage of equipment in inpatient units, and to describe any factors that could contribute to contamination of the processed equipment during transport to and storage in inpatient units. The study was approved by the Research Ethics Committee of the hospital (Protocol 167/2011), and pertanent ethical aspects were observed. Data were collected from July to September 2012 using two instruments, both of which were evaluated and went through pilot testing: a check list completed through direct observation, and an interview of nurses responsible for managing each unit. Those responsible for the care, custody, and transportation of equipment were processed predominantly by practicing nurses (72.7%). No storage system from 11 inpatient units met all of the recommendations regarding the structural and material resources for the storage of processed equipment, ten units (90.9%) kept equipment in non-dedicated areas, and other materials were kept near products that were not sterilized. Access to clean storage was unrestricted in all units, and did not adhere to most of the recommendations for the storage and distribution of processed equipment, only three items had adhere, two with low frequency: inventory of processed equipment kept in the storage area (100.0%); proper identification of equipment on the shelves (27.3%), and maintaining stock rotation (9.1%). The nursing staff was most frequently involved in recorded events, the most frequent across all units being: "handled without proper hand hygiene" (20.0%) and "handled excessively" (18.3%) processed equipment. The event "opening the package and closing it again", considerede serious, was the most frequent in basins, gowns and drapes, which are products frequently packaged in pairs. The packages of compression dressings, gauze, and bandages often "fell down" and were picked up off the floor and used. The material sterilization center offered no carts to transport the processed equipment to inpatient units and the carts brought from the units themselves were open, with irregular and difficult to clean surfaces, like shopping carts, which are considered unsuitable for transport. The study also revealed carelessness on the part of the healthcare team with regard to processed equipment following distribution to inpatient units, which presents a risk to the maintenance of the sterile environment, and consequently, patient safety.
Estudio exploratorio, transversal y descriptivo, con abordaje cuantitativo, realizado en 11 unidades de internación de un hospital de enseñanza, público y de grande porte del municipio de Goiânia/GO. El objetivo general fue analizar la seguridad de productos para la salud procesados durante su transporte y almacenaje, en unidades de internación y los específicos fueron: identificar los responsables por los cuidados con los productos para la salud procesados después de su distribución en las unidades de internación; identificar aspectos estructurales y recursos materiales disponibles para el transporte y almacenaje de productos para la salud, en unidades de internación; describir los cuidados dispensados por el equipo de salud, con el transporte y almacenaje de productos para la salud, en las unidades de internación y describir los eventos relacionados que pueden contribuir para la contaminación de los productos para la salud procesados durante el transporte y almacenaje en las unidades de internación. El estudio fue aprobado por el Comité de Ética en Pesquisa del hospital local del estudio (protocolo nº 167/2011) y fueron observados los aspectos éticos pertinentes. Los datos fueron recolectados de julio a septiembre de 2012, por medio de dos instrumentos evaluados y sometidos a prueba experimental: un check list rellenado por medio de observación directa y una entrevista realizada a los enfermeros responsables por la gerencia de cada unidad. Los responsables por los cuidados con el transporte y guardia de PPS procesados eran predominantemente los técnicos de enfermería (72,7%). Ningún sistema de guardia de las 11 unidades de internación atendía a todas las recomendaciones acerca de los aspectos estructurales y recursos materiales para el almacenaje de PPS procesados, siendo que diez unidades (90,9%) los guardaban en áreas no exclusivas, destinadas a otras funciones y junto a productos no esterilizados. El acceso al área de guardia era irrestricto en todas las unidades y no hubo adhesión a la mayoría de las recomendaciones para la guardia y distribución de PPS procesados, apenas tres ítems tuvieron adhesión, dos con bajas frecuencias: control de la entrada de los PPS procesados en la área de guardia (100,0%); disposición en las platilleras de acuerdo con la identificación (27,3%) y organización según el orden cronológico (9,1%). El equipo de enfermería fue el que más frecuentemente se involucró en los eventos relacionados, que cuando son sumados en todas las unidades los más frecuentes fueron: “manipular sin higienizar las manos” (20,0%) y “manipular en exceso” (18,3%) PPS procesados. El evento “abrir el embalaje y cerrarlo nuevamente”, considerado grave, fue el más frecuente en vasijas, capotes y campos quirúrgicos, correspondiendo a aquellos productos embalados en pares. Los paquetes de compresas, gasas y fajas frecuentemente “se cayeron al piso” y fueron recogidos para uso. El CME no ofrecía los vehículos para transporte de PPS procesados a las unidades de internación y aquellos pertenecientes a las propias unidades eran carritos abiertos, con superficie irregular y de difícil limpieza, como los usados en supermercados, considerados inadecuados para transporte. El estudio reveló el descuido del equipo de salud con los PPS procesados después que ellos son distribuidos a las unidades de internación, lo que coloca en riesgo el mantenimiento de su esterilidad y consecuentemente la seguridad del usuario.
Estudo exploratório, transversal e descritivo, com abordagem quantitativa, realizado em 11 unidades de internação de um hospital de ensino, público e de grande porte do município de Goiânia/GO. O objetivo geral foi analisar a segurança de produtos para saúde processados durante o seu transporte e armazenamento, em unidades de internação e os específicos foram: identificar os responsáveis pelos cuidados com os produtos para saúde processados após sua distribuição nas unidades de internação; identificar aspectos estruturais e recursos materiais disponíveis para o transporte e armazenamento de produtos para saúde, em unidades de internação; descrever os cuidados dispensados pela equipe de saúde, com o transporte e armazenamento de produtos para saúde, nas unidades de internação e descrever os eventos relacionados que podem contribuir para contaminação dos produtos para saúde processados durante o transporte e armazenamento nas unidades de internação. O estudo foi aprovado pelo Comitê de Ética em Pesquisa do hospital local do estudo (protocolo nº 167/2011) e foram observados os aspectos éticos pertinentes. Os dados foram coletados de julho a setembro de 2012, por meio de dois instrumentos avaliados e submetidos a teste piloto: um check list preenchido por meio de observação direta e uma entrevista aplicada aos enfermeiros responsáveis pelo gerenciamento de cada unidade. Os responsáveis pelos cuidados com o transporte e guarda de PPS processados eram predominantemente os técnicos de enfermagem (72,7%). Nenhum sistema de guarda das 11 unidades de internação atendia todas as recomendações acerca dos aspectos estruturais e recursos materiais para o armazenamento de PPS processados, sendo que dez unidades (90,9%) os guardavam em áreas não exclusivas, destinadas a outras funções e junto a produtos não esterilizados. O acesso à área de guarda era irrestrito em todas as unidades e não houve adesão à maioria das recomendações para a guarda e distribuição de PPS processados, apenas três itens tiveram adesão, dois deles com baixas frequências: controle da entrada dos PPS processados na área de guarda (100,0%); disposição nas prateleiras de acordo com a identificação (27,3%) e organização segundo ordem cronológica (9,1%). A equipe de enfermagem foi a que mais frequentemente se envolveu nos eventos relacionados, que quando somados em todas as unidades os mais frequentes foram: “manusear sem higienizar as mãos” (20,0%) e “manusear excessivamente” (18,3%) PPS processados. O evento “abrir a embalagem e fechar novamente”, considerado grave, foi o mais frequente em bacias, capotes e campos cirúrgicos, correspondendo àqueles produtos embalados em pares. Os pacotes de compressas, gazes e ataduras frequentemente “caíram no chão” e foram recolhidos para uso. O CME não oferecia os veículos para transporte de PPS processados às unidades de internação e aqueles pertencentes às próprias unidades eram carrinhos abertos, com superfície irregular e de difícil limpeza, no modelo dos usados em supermercados, considerados inadequados para transporte. O estudo revelou o descuidado da equipe de saúde com os PPS processados depois que eles são distribuídos às unidades de internação, o que coloca em risco a manutenção de sua esterilidade e consequentemente a segurança do usuário.

Styles APA, Harvard, Vancouver, ISO, etc.

36

Simons, Alexis. « Caractérisation et maîtrise de la prolifération microbienne dans des produits biosourcés pour des bâtiments sains et durables ». Thesis, Toulouse 3, 2018. http://www.theses.fr/2018TOU30246/document.

Texte intégral

Résumé :

Les impacts de la construction sur l'environnement et sur la santé des habitants sont aujourd'hui des enjeux prioritaires. Les matériaux en terre crue connaissent un essor important pour de nombreuses raisons (écologique, économique, etc.), mais des questions se posent sur leur sensibilité à la prolifération des moisissures vis-à-vis de la qualité de l'air intérieur. Au cours de ces travaux, les flores bactériennes et fongiques présentes sur des supports en terre crue, biosourcés ou non, au sein d'habitations, ainsi que dans les matières premières, ont été caractérisées selon des méthodes par culture et par métabarcoding. Les champignons détectés sont similaires à ceux présents dans les habitations conventionnelles. L'ajout de fibres végétales ne modifie pas la structure des communautés fongiques mais rend le matériau plus sensible à la prolifération. Celle-ci n'intervient qu'en condition d'accident hydrique. Des approches de lutte biologique à partir de bactéries ont été initiées pour inhiber la prolifération fongique sur ces matériaux
Impacts of building on environment and on health of inhabitants are nowadays priority issues. The interest for earthen materials is increasing for many reasons (ecological, economical, etc.), but some questions are raised about their fungal proliferation sensitivity considering the quality of indoor air. This work consists in characterizing by cultural and metabarcoding methods the fungal and bacterial communities on the surface of earthen building materials, biobased or not, and raw materials. Detected fungi are related to those which are identified in conventional buildings. The addition of vegetal fibers don't modify the fungal communities structure, but make the material more favorable for proliferation. The fungal development appears only under water damage condition. Biocontrol methods with bacteria have been initiated in order to inhibit the fungal proliferation on these materials

Styles APA, Harvard, Vancouver, ISO, etc.

37

Fraga, Ricardo Carvalhaes. « Potencial antimicrobiano de materiais restauradores contendo fluor, durante a reação de presa e apos hidratação ». [s.n.], 1997. http://repositorio.unicamp.br/jspui/handle/REPOSIP/289709.

Texte intégral

Résumé :

Orientador: Luis Roberto Marcondes Martins
Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Odontologia de Piracicaba
Made available in DSpace on 2018-07-23T00:04:28Z (GMT). No. of bitstreams: 1 Fraga_RicardoCarvalhaes_D.pdf: 2772557 bytes, checksum: 0370c405fbc3fe9273a3caad7a507335 (MD5) Previous issue date: 1997
Resumo: Foi realizada uma pesquisa in vitro, utilizando-se como método de avaliação a inibição de crescimento microbiano em caldo de cultura, com o intuito de determinar o potencial antibacteriano de materiais restauradores que contém flúor, além de avaliar a relação dessa capacidade com a alteração do pH do meio aquoso circundante, provocada pelos próprios materiais. Avaliou-se a atividade inibitória dos materiais, durante a reação de presa, contra cinco espécies bacterianas (Streptococcus sobrinus, Streptococcus sanguis, Streptococcus salivarius, Streptococcus mutans e Lactobacillus caseI). Foi testada também a capacidade antibacteriana dos materiais após a hidratação dos mesmos por 72 horas, utilizando-se para essa fase da pesquisa apenas duas espécies (S. mutans e S. sanguis). Na terceira fase do experimento mensurou-se a alteração de pH em água destilada, provocada pelos materiais, após a hidratação por 3 minutos, 4 horas e 72 horas. Constatou-se que, quando testados durante a reação de presa, a resina composta com flúor (Tetric) e a resina modificada por poliácidos (Dyract) atuaram de modo semelhante ao grupo controle, representado por uma resina composta sem flúor (Charisma), não apresentando atividade antibacteriana contra as cinco espécies. Os materiais Vidrion N, Vitremer, Chelon-Silver e Chelon-Fil apresentaram ação variada contra o crescimento microbiano nessa fase. Após a hidratação, quando testados contra S.sanguis e S.mutans, o material híbrido Vitremer foi o que apresentou maior ação inibitória contra o crescimento dos microrganismos, seguido pelo Vidrion N e pelo Dyract, que passou nesta fase a possuir ação antimicrobiana. Os ionoméricos Chelon Silver e Chelon-Fil perderam significativamente o potencial antibacteriano, e a resina composta Tetric mostrou uma ação praticamente nula. O Dyract foi o único que apresentou queda do pH do meio, quando realizada a hidratação pelo período de 4 horas, indicando que a acidificação superficial desse material acontece tardiamente pela absorção de água, podendo, inclusive, estar relacionada com a sua capacidade antibacteriana
Abstract: The aim of this in vitro study was to determine the antibacterial potential of restorative materiais with fluoride-containing. In addition, it was evaluated the relation between antibacterial activity and pH changes on the surrounding aqueous medium of the these materiais. It was evaluated the inhibitory activity of the materiais, during setting reaction, against five bacterial species ( Streptococcus sObrinus, Streptococcus sanguis, Streptococcus salivarius, Streptococcus mutans and Lactobacillus casei). On .the second phase of the experiment, the materiais were tested on their antibacterial activity afier their hydration for 72 hours, using only two species in this phase (S. mutans and S. sanguis). On the third phase, it was measured the pH alterations in distilled water, caused by the materiais afier hydration for 3 minutes, 4 hours and 72 hours. The composite resin with fluoride-containing (Tetric) and the resin modified by polyacids (Dyract) acted the same effect as the control group represented by a fluoride-free composite resin (Charisma), when tested during setting reaction, not showing any antibacterial effect against the five species. The materiais Vidrion N, Vitremer, Chelon-Silver and Chelon-Fil showed varying action against bacterial growth in this phase. Afier hydration, when tested against S. sanguis and S. mutans, the hybrid material Vitremer showed the highest inhibition action against bacterial growth, followed by Vidrion. N and Dyract, which started showing antimicrobial potential in this phase. The glass ionomers cements Chelon Fil and Chelon-Silver had a relevant loss of antibacterial effects, showing a similar action of the composite resins. Dyract was the only one to present a pH fali of the environment medium, when hydration happened in a four-hour period, indicating a late superficial acidification of this material by water absorption, which may as well be related to its antibacterial activity
Doutorado
Dentística
Doutor em Clínica Odontológica

Styles APA, Harvard, Vancouver, ISO, etc.

38

Zanetti, Glauco Rangel. « Influencia do material de inclusão e apoio da grade metalica na estabilidade de proteses parciais removiveis de extremidade livre durante o processamento das bases polimerizadas por energia de microondas ». [s.n.], 2000. http://repositorio.unicamp.br/jspui/handle/REPOSIP/290537.

Texte intégral

Résumé :

Orientador: Celia Marisa Rizzatti Barbosa
Tese (doutorado) - Universidade Estadual de Campinas. Faculdade de Odontologia de Piracicaba
Made available in DSpace on 2018-07-28T03:15:46Z (GMT). No. of bitstreams: 1 Zanetti_GlaucoRangel_D.pdf: 4522575 bytes, checksum: 4717fe0797e79a21a39c9cbeebb8ac1d (MD5) Previous issue date: 2000
Resumo: Este estudo avaliou a influência do material de inclusão (gesso tipo 11 Herodent@ "G", silicone por condensação laboratorial Zetalabor@ "Z"), e da configuração da porção distal da grade metálica (com apoio "C" e sem apoio "s" sobre o modelo), nas alterações horizontais (esquerda "HE" e direita "HD") e verticais (esquerda "VE" e direita "VD") , entre as porções distais de estruturas metálicas de prõteses parciais removíveis (PPR's) e seus respectivos modelos durante o processamento das bases em resina acrílica. Foram utilizados modelos simulando uma arcada inferior parcialmente desdentada classe I de Kennedy. Quarenta amostras padronizadas foram divididas em quatro grupos. As bases foram processadas com uma resina polimerizada por energia de microondas (Onda-Cryl@). Os dados foram submetidos à análise de variância e as médias, ao teste de Tukey (pAbstract: This study evaluated the effect of two types of investment material ("G", type 11 dental stone, Herodent@; "Z", condensation silicone, Zetalabor@) and two types of design of the distal portion of the metallic framework ("S", with support in the model; "N", without support in the model) in the horizontal ("H L", left; "HR", right) and vertical ('VL", left; 'VR", right) distance changes between the distal portion of the metallic framework and their respective models during processing of the acrylic bases. A lower Kennedy Class I model was used. Forty standardized RPD's were prepared and equally divided into 4 groups. The RPD's bases were processed using a microwave-cured acrylic resin (OndaCryl@). Data was submitted to a "Tukey's Studentized" test (pDoutorado
Protese Dental
Doutor em Clínica Odontológica

Styles APA, Harvard, Vancouver, ISO, etc.

39

David, Grégoire. « Eco-conversion de résidus lignocellulosiques de l'agriculture en matériaux composites durables à matrice biopolyester ». Thesis, Montpellier, 2019. http://www.theses.fr/2019MONTG030.

Texte intégral

Résumé :

Cette thèse consiste à développer et étudier de nouveaux matériaux composites biosourcés et biodégradables à partir de constituants dérivés des déchets de l'agriculture dans le cadre du projet européen NoAW (https://noaw2020.eu). Tous les composants sont dérivés de sous-produits agricoles : des polyhydroxyalcanoates (PHA, biopolyester bactérien et biodégradable en conditions naturelles) produits par digestion anaérobie d’effluents agricoles sont utilisés comme matrices et des fibres de sarments de vigne comme charges de renfort. Les composites sont préparés par extrusion. L'objectif de cette thèse est d'apporter de nouvelles connaissances sur les relations entre le procédé de mise en œuvre des biocomposites, leur structure et leurs propriétés fonctionnelles. Les biocomposites sont développés en considérant une balance performance-coût environnemental. Pour cela, la thèse se focalise sur 2 questions scientifiques majeures : (i) étude de l’impact de l’interface charge/matrice sur les propriétés fonctionnelles des matériaux biocomposites via pré-traitements de surface des particules lignocellulosiques ; (ii) étude de la durabilité de tels matériaux par évaluation dès la conception des impacts environnementaux. Ainsi, une attention particulière est accordée à l’interface charge/matrice, identifiée comme un facteur clé influençant les propriétés finales du composite. Un prétraitement de surface des fibres sans solvant (chromatogénie) est adapté afin de moduler l’interface charge/matrice. Cette nouvelle méthode d’estérification en voie gazeuse est tout d’abord étudiée sur des particules micrométriques de cellulose. Une fois la preuve de concept établie, elle est appliquée aux fibres lignocellulosiques, plus complexes. Les sarments de vigne, déchets agricole abondant en région Occitanie, sont étudiés comme ressource potentielle pour la production de charges de renfort. Une fois collectés et séchés, ils sont broyés en voie sèche afin d’obtenir des particules micrométriques. La variabilité de la matière première étant un des verrous concernant l’utilisation de la biomasse par les industriels, différents cépages sur plusieurs années ont été étudiés. Dans une logique de bioraffinerie, l’extraction préalable de molécules d’intérêt tels que les polyphénols est envisagée avant d’utiliser le résidu, à savoir les sarments épuisés, comme charge de renfort. L’impact environnemental des matériaux développés est évalué afin de guider les choix stratégiques et obtenir le matériau alliant à la fois performance et faible empreinte écologique. Une analyse de cycle de vie dans le cadre d’une application de barquette rigide alimentaire est réalisée en réunissant des données des acteurs de la filière. De plus, une étude de la biodégradabilité des matériaux finaux est menée. Cette thèse englobe plusieurs composantes pluridisciplinaires afin d’avoir une vision d’ensemble et décloisonnée des matériaux composites mis au point
This thesis aims at developing new fully biosourced and biodegradable composite materials from agricultural residues in the frame of the European project NoAW (https://noaw2020.eu). All the components are derived from agro-wastes: polyhydroxyalkanoates (PHA, bacterial biopolyester and biodegradable in natural conditions) produced by anaerobic digestion of agricultural effluents are used as matrix and vine shoot fibers as fillers. Biocomposites are prepared by melt extrusion. The objective of this thesis is to bring new knowledge on the relationships between the processes used to produce the fillers and the biocomposites, the resulting structure of biocomposites and their functional properties. Biocomposites are developed considering a balance between performance and environmental cost. For this purpose, the thesis focuses on 2 major scientific questions: (i) study of the impact of the filler/matrix interface on the functional properties of biocomposite materials via surface pre-treatments of lignocellulosic particles; (ii) study of the durability of such materials by assessment from the design of the environmental impacts. Thus, special attention is given to the filler/matrix interface, identified as a key factor for the final properties of the composite. A solvent-free surface pretreatment of fibers (chromatogeny) is adapted to modulate the filler/matrix interface. This new method of gas-phase esterification is first studied on micrometric particles of cellulose. Once the proof of concept is established, it is applied to lignocellulosic fibers that are more complex. The vine shoots, agricultural waste abundant in Occitania region, are studied as a potential resource for the production of fillers for composites. Once collected and dried, they are milled using dry fractionation to obtain micrometric sized particles. The variability of the raw material being one of the bottlenecks concerning the use of lignocellusoic biomass by manufacturers, different grape species over several years are studied. In a biorefinery approach, the extraction of molecules of interest, e.g. polyphenols, is considered before using the residue, namely exhausted shoots, as a reinforcing fillers. The environmental impact of the produced biocomposites is evaluated to guide strategic choices and obtain materials displaying a good balance between performance and environmental footprint. A life cycle assessment in the context of a food rigid tray application is carried out, collecting data from sector’s players. In addition, a study of the biodegradability of the final materials is conducted. This thesis encompasses multidisciplinary fields in order to have a decompartmentalized overview of the developed composite materials

Styles APA, Harvard, Vancouver, ISO, etc.

40

Tiscar, Cervera Juan Miguel. « Estudio y modelización del comportamiento reológico de materiales cerámicas pulverulentos durante el llenado de moldes ». Doctoral thesis, Universitat Jaume I, 2018. http://hdl.handle.net/10803/663159.

Texte intégral

Résumé :

Las baldosas cerámicas son placas de escaso grosor fabricadas con arcillas,sílice, fundentes, colorantes y otros materiales, generalmente utilizadas comorevestimientos. Durante su fabricación pueden aparecer problemas de heterogeneidad, debido a una distribución deficiente del polvo en los alvéolos del molde en el que se conforman. Como respuesta a esta problemática, en este trabajo se ha desarrollado un programa informático que permite simular, estudiar y comprender el llenado de moldes del proceso de fabricación de baldosas. El método utilizado para realizar la simulación se denomina Método de los Elementos Discretos (en inglés “Discrete Elements Method”, abreviado como DEM). Asimismo, se ha propuesto una metodología novedosa para la calibración del modelo, el cual ha sido validado utilizando un sistema de alimentación de polvo piloto. Este equipo también se ha utilizado para investigar el llenado de moldes. Finalmente se realizaron una serie de simulaciones orientadas a mostrar las capacidades del programa desarrollado.
Ceramic tiles are thin plates made from clays, silica, fluxes, colorants and other materials, generally used as wall or floor coverings. During its manufacturing process, some heterogeneity problems may appear, due to a poor distribution of the powder in the mold which they are formed in. As a response to this problem, a computer program that allows for simulation, study and understanding of the mold filling of the tile manufacturing process has been developed. The method used to perform the simulation is called the Discrete Elements Method (abbreviated as DEM). Likewise, a novel methodology has been proposed for the calibration of the model, which has been validated using a prototype of a powder feeding system. This equipment has also been used to study the mold filling. Finally, a series of simulations were carried out in order to show the capabilities of the program developed.

Styles APA, Harvard, Vancouver, ISO, etc.

41

Schmitz, Gabriela Cenci. « Avaliação da alteração térmica da câmara pulpar durante a colagem de bráquetes ortodônticos ». Pontifícia Universidade Católica do Rio Grande do Sul, 2015. http://hdl.handle.net/10923/7282.

Texte intégral

Résumé :

Made available in DSpace on 2015-05-22T12:38:45Z (GMT). No. of bitstreams: 1 000469172-Texto+Completo-0.pdf: 823400 bytes, checksum: 095e93ad0abe67b38883346b9108692f (MD5) Previous issue date: 2015
Introduction: the objective of this study was to evaluate the temperature variation of the pulp chamber during brackets bonding in different teeth types, with and without primer and in healthy or filled teeth.Materials and Methods: ninety human permanent teeth were used, 30 mandibular incisors, 30 maxillary bicuspid and 30 mandibular third molars, which were divided into 9 groups according to bonding technique (with or without light-curing primer), tooth type, filled or healthy tooth and thickness. A K-type thermocouple connected in a digital thermometer was introduced into the pulp chamber. Periapical radiographs were taken to check the thermocouple positioning and the brackets were bonded using a LED. The initial and maximum temperature reached during light curing were used to calculate the temperature variation.Results: the ANCOVA analysis showed that the bonding technique and tooth type (p≤0. 05) influenced the temperature variation. There was a greater increase in temperature using primer. Regarding the tooth type, the incisors experienced a major temperature increase, followed by molars and bicuspids. There was no statistically significant difference for healthy or filled teeth groups and thickness factor.Conclusion: a molar showed the lowest temperature variation with 0. 2°C and a lower incisor with the greatest variation of 4. 3°C. The bonding technique using primer and adhesive caused a greater temperature range compared to the bonding with adhesive only. The mandibular incisor obtained a greater temperature range, then the molar and bicuspid. Therefore, the brackets bonding didn`t exceed the 5,5ºC recommended for the pulp health maintenance. Key words: light curing of dental adhesives, thermometers, braces, hot temperature, orthodontics.
Introdução: o objetivo desse estudo foi avaliar a variação de temperatura da câmara pulpar durante a colagem de bráquetes em diferentes tipos de dentes, com e sem utilização de primer e em dentes hígidos e restaurados.Materiais e Métodos: foram utilizados 90 dentes permanentes humanos, sendo 30 incisivos inferiores, 30 primeiros pré-molares superiores e 30 terceiros molares inferiores, divididos em 9 grupos de acordo com a técnica de colagem, com ou sem primer, tipo de dente e se o dente era hígido ou restaurado. Um termopar tipo K foi introduzido na câmara pulpar e conectado à um termômetro digital. Radiografias periapicais foram realizadas para conferir o posicionamento do termopar no interior da câmara pulpar e os bráquetes foram colados utilizando um LED. As temperaturas inicial e máxima atingida durante a fotopolimerização foram utilizadas para calcular a variação da temperatura.Resultados: a análise de ANCOVA mostrou que a variação de temperatura foi influenciada pela técnica de colagem e pelo tipo de dente (p≤0,05). Utilizando primer houve um maior aumento de temperatura em relação ao grupo sem primer. Quanto ao tipo de dente, os incisivos sofreram um maior aumento de temperatura, seguido dos molares e pré-molares. Não houve diferença estatisticamente significativa para os grupos de dentes hígidos ou restaurados e para o fator espessura.Conclusão: o dente que obteve menor variação de temperatura foi um molar com 0,2°C e, um incisivo inferior, com a maior variação, de 4,3°C. A técnica de colagem utilizando primer e adesivo causou uma variação de temperatura maior se comparado à colagem apenas do adesivo. O incisivo inferior obteve uma maior variação de temperatura, seguida do molar e pré-molar. Portanto, a colagem de bráquetes não excedeu os 5,5ºC preconizados para manutenção da saúde pulpar.

Styles APA, Harvard, Vancouver, ISO, etc.

42

Lima, Paulo DemÃtrios da Silva. « Medida Padronizada da TendÃncia Ã Fissura de Corpos de Prova CerÃmicos Durante o Processo de Secagem ». Universidade Federal do CearÃ, 2002. http://www.teses.ufc.br/tde_busca/arquivo.php?codArquivo=7295.

Texte intégral

Résumé :

FundaÃÃo de Amparo Ã Pesquisa do Estado do CearÃ
Essa dissertaÃÃo apresenta um mÃtodo de medir a tendÃncia de formaÃÃo de fissuras em corpos-de-prova circulares de 35 mm de diÃmetro em argila durante a secagem. Esses corpos-de-prova foram expostos a uma corrente de ar sob condiÃÃes de temperatura e umidade controladas. Dependendo das condiÃÃes de secagem uma fissura Ã produzida e sua extensÃo avaliada numa escala numÃrica. Cinco tipos de argila foram testadas no aparato de secagem montado no LaboratÃrio de CerÃmica do curso de Engenharia QuÃmica da UFC. TambÃm foram levantadas curvas de secagerm dessas amostras sob vÃrias condiÃÃes de temperatura e umidade e correlacionadas com dados de projeto de secadores industriais. As amostras Caulim e Sobral apresentaram similaridades na tendÃncia a fissura e as amostras Celene e Filito nÃo apresentaram nenhuma fissura sob as condiÃÃes de temperatura e umidade expostas. A amostra TaguÃ apresentou comportamento anÃmalo. O secador pode ser usado para testar a tendÃncia âa fissura em qualquer tipo de argila. O teste mostrou possuir reprodutibilidade apesar do comportamento anÃmalo de uma das amostras.

Styles APA, Harvard, Vancouver, ISO, etc.

43

Campos, José Alexandre de. « Avaliação experimental do desgaste de canto durante o processo de eletroerosão do AISI H13 ». Universidade Tecnológica Federal do Paraná, 2014. http://repositorio.utfpr.edu.br/jspui/handle/1/1165.

Texte intégral

Résumé :

A fabricação de moldes e matrizes são ricas em detalhes e geometrias complexas, exigindo tecnologias mais inovadoras e precisas. Um dos processos que se destaca na fabricação de moldes e matrizes, é o de eletroerosão por penetração (Electrical Discharge Machining - EDM). A usinagem por descargas elétricas é classificada como um processo de fabricação de geometria não definida, onde a remoção de material é realizada por repetidas descargas elétricas entre dois eletrodos eletricamente condutores. O desgaste da ferramenta é um dos principais parâmetros de medida no desempenho da usinagem por EDM. O maior problema ocasionado pelo desgaste de canto do eletrodo é a mudança de geometria da ferramenta no decorrer da usinagem, alterando a tolerância geométrica e o dimensional da cavidade. O presente trabalho propõe avaliação dimensional do desgaste de canto do eletrodo, no decorrer da usinagem do processo de EDM, variando o ângulo de superfície frontal do eletrodo. Outro propósito é a criação de um índice, chamado de taxa de arredondamento, que leva em consideração as áreas de desgaste de canto do eletrodo em função da área removida de material da peça. Os resultados mostraram que os eletrodos de cobre, cobre tungstênio e grafite, tem um grande crescimento de raio de canto no inicio da usinagem, estabilizando esses valores com tempo maiores de processo. O ângulo de superfície frontal do eletrodo influência diretamente no desgaste de canto do eletrodo. Os eletrodos de grafite não apresentaram comportamento de arredondamento de desgaste de canto durante os ensaios. Para o índice de taxa de arredondamento os eletrodos de cobre tungstênio tiveram o menor valor apresentado na usinagem do AISI H13.
The manufacture of molds and dies are rich in detail and complex geometries, requiring more innovative and precise technologes. One of the processes that stands out in the manufacture of molds and dies, is to EDM by penetration (Electrical Discharge Machining - EDM). The cutting by electrical discharge is classified as a non-defined geometry manufacturing process where material removal is carried out by repeated electrical discharge between two electrodes electrically conductive. The tool wear is a major measurement parameters in machining performance by EDM. The biggest problem caused by the electrode corner wear is the tool geometry change during the machining by changing the geometric tolerance and dimensional cavity. This paper proposes dimensional evaluation of the electrode corner wear, during the machining of the EDM process, varying the front surface of the electrode angle. Another purpose is to create an index, called rounding rate, which takes into account the areas of electrode corner wear due to the removed area of the workpiece material. The results showed that the copper electrode, copper tungsten and graphite, has a large corner radius growth at the beginning of machining, stabilizing these values with higher process time. The front surface of the electrode angle influence directly on the electrode corner wear. Graphite electrodes showed no corner wear rounding behavior during the tests. For rounding rate index tungsten copper electrodes had the lowest value presented in the machining of AISI H13.

Styles APA, Harvard, Vancouver, ISO, etc.

44

Lima, Paulo Demétrios da Silva. « Medida padronizada da tendência à fissura de corpos-de-prova cerâmicos durante o processo de secagem ». reponame:Repositório Institucional da UFC, 2002. http://www.repositorio.ufc.br/handle/riufc/2502.

Texte intégral

Résumé :

LIMA, P. D. S. Medida padronizada da tendência à fissura de corpos-de-prova cerâmicos durante o processo de secagem. 2002. 80 f. Dissertação (Mestrado em Engenharia e Ciência de Materiais) - Centro de Tecnologia, Universidade Federal do Ceará, Fortaleza, 2002.
Submitted by Marlene Sousa (mmarlene@ufc.br) on 2012-04-19T17:37:17Z No. of bitstreams: 1 2002_dis_pdslima.pdf: 2691467 bytes, checksum: 0325089d3b2f0146e286b9e645a12587 (MD5)
Approved for entry into archive by Marlene Sousa(mmarlene@ufc.br) on 2012-04-19T17:38:26Z (GMT) No. of bitstreams: 1 2002_dis_pdslima.pdf: 2691467 bytes, checksum: 0325089d3b2f0146e286b9e645a12587 (MD5)
Made available in DSpace on 2012-04-19T17:38:26Z (GMT). No. of bitstreams: 1 2002_dis_pdslima.pdf: 2691467 bytes, checksum: 0325089d3b2f0146e286b9e645a12587 (MD5) Previous issue date: 2002
This thesis presents a method to measure a tendency to cracking of 35-mm-diameter circular samples of clay during drying. These samples were exposed to a current of air under controlled temperature and humidity. Depending on the drying conditions a crack is produced and its length is compared to a numerical scale. Five different clays were tested in a drying apparatus built in the Ceramics Laboratory of the Chemical Engineering Course at the Federal University of Ceará. Drying curves were plotted under several temperature and humidity conditions for the five clays and correlated with industrial drying project data. The samples Caulim and Sobral showed similarity in cracking tendency and the samples Celene and Filito did not showed any crack in every diferent conditions of temperature and humidity exposed. The last sample Tagua showed an anomalous behaviour. The dryer can be used to test a cracking tendency in every kind of clay. The test showed capable of being reproduced in despite of the anomalous behaviour of one of the samples.
Essa dissertação apresenta um método de medir a tendência de formação de fissuras em corpos-de-prova circulares de 35 mm de diâmetro de argilas durante a secagem. Esses corpos-de-prova foram expostos a uma corrente de ar sob condições de temperatura e umidade controladas. Dependendo das condições de secagem uma fissura é produzida e sua extensão avaliada numa escala numérica. Cinco tipos de argila foram testadas no aparato de secagem montado no Laboratório de Cerâmica do curso de Engenharia Química da UFC. Também foram levantadas curvas de secagem dessas amostras sob várias condições de temperatura e umidade e correlacionadas com dados de projeto de secadores industriais. As amostras Caulim e Sobral apresentaram similaridades na tendência a fissura e as amostras Celene e Filito não apresentaram nenhuma fissura sob todas as condições de temperatura e umidade expostas. A amostra Taguá apresentou um comportamento anômalo. O secador pode ser usado para testar a tendência à fissura em qualquer tipo de argila. O teste mostrou possuir reprodutibilidade apesar do comportamento anômalo de uma das amostras.

Styles APA, Harvard, Vancouver, ISO, etc.

45

Oliveira, Daniel Pinto de. « Avaliação "in vitro" da remoção de material obturador empregando diferentes tecnicas durante o retratamento endodontico ». [s.n.], 2002. http://repositorio.unicamp.br/jspui/handle/REPOSIP/290889.

Texte intégral

Résumé :

Orientador : Fabricio Batista Teixeira
Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Odontologia de Piracicaba
Made available in DSpace on 2018-08-01T21:19:32Z (GMT). No. of bitstreams: 1 Oliveira_DanielPintode_M.pdf: 2108033 bytes, checksum: ba94b8ab1f280447cfa9f633362c9f6f (MD5) Previous issue date: 2002
Resumo: O presente estudo avaliou a eficiência entre diferentes técnicas de remoção de material obturador quanto à limpeza das paredes dos canais radiculares e extrusão apical de debris. Foram utilizados 120 pré-molares inferiores humanos, armazenados em solução de formol a 10% e divididos aleatoriamente em 6 grupos. Os dentes foram instrumentados e obturados, sendo em seguida, armazenados em estufa a 370C e umidade durante 60 dias. O retratamento foi realizado de acordo com as seguintes técnicas: limas Flexofile com Xilol; limas Flexofile e Hedstrom com Xilol; Profile GT com Xilol; Flexofile com clorexidina gel; limas Flexofile e Hedstrom com clorexidina gel; Profile GT com clorexidina gel. A extrusão apical de debris foi mensurada no decorrer dos procedimentos e a capacidade de limpeza das paredes por três procedimentos distintos: radiograficamente, através da lupa estereoscópica e do microscópio eletrônico de varredura (M.EV.). Os dentes foram radiografados no sentido orto e mesio-radial, sendo as radiografias analisadas quanto à presença de remanescentes de material obturador por dois examinadores simultaneamente. Em seguida foram fraturados longitudinalmente e as imagens capturadas através da lupa estereoscópica e transferidas ao computador. A quantidade de material obturador residual, foi mensurada utilizando o programa "Imagelab 98" e os resultados analisados estatisticamente. Cinco elementos de cada grupo foram analisados em M.E.V. nos 5 mm apicais. Os resultados indicaram que os grupos que utilizaram a clorexidina gel, com instrumentação manual ou rotatória, apresentaram menor extrusão de debris, sendo similar ao grupo com xilol e instrumentação rotatória, não diferindo estatisticamente entre si. Analisando-se a limpeza das paredes dos canais radiculares, os grupos que utilizaram clorexidina gel, independente da instrumentação empregada, apresentaram melhores resultados
Abstract: The present study evaluated the efficiency among different techniques of endodontic retreatment analyzing the cleaning of the root canal walls and apical extrusion of debris. The cleaning ability was analyzed by three different methods: radiografically, using the stereoscopic loupe and the scanning electronic microscope (SEM). Hundred twenty human lower pre-molars recently extracted stored in formol solution to 10% were used these teeth were divided randomly in six groups. They were instrumented, filled and stored at 37°C for 60 days. The canais were retreated in agreement with each group: Flexofile + xylene; Flexofile/ Hedstrom + xylene; Profile GT + xylene; Flexofile + chlorhexidine gel; Flexofile/ Hedstrom + chlorhexidine gel; Profite GT + chlorhexidine gel. After the accomplishment of ali procedures, including the collecting of the debris apically extruded, the teeth were radiographed in two different angles. They were fractured longitudinally and the images were captured using the stereomicroscope and transferred to the personal computer. The residual obturation material total area, was calculated by the program " Imagelab 98 " and the results statistically analyzed. Five elements of each group were observed in the SEM to compare the cleaning of the root canal walls, including the- apical thirds. The groups that used the chlorhexidine gel, with manual or rotary instrumentation, showed smaller debris extrusion, as well as the group with xylene and rotary instrumentation, not differing statistically to each other. Considering the cleaning of the root canal walls, the groups that used chlorhexidine gel showed better results independently the instrumentation used.
Mestrado
Endodontia
Mestre em Clínica Odontológica

Styles APA, Harvard, Vancouver, ISO, etc.

46

Nogueira, Helen Cristina. « Exposição biomecânica durante o manuseio de caixas em ambiente real e simulado com trabalhadores industriais ». Universidade Federal de São Carlos, 2016. https://repositorio.ufscar.br/handle/ufscar/8674.

Texte intégral

Résumé :

Submitted by Aelson Maciera (aelsoncm@terra.com.br) on 2017-04-24T17:31:20Z No. of bitstreams: 1 TeseHCN.pdf: 982841 bytes, checksum: bcab3da38d92906a3e65c80c31f92e51 (MD5)
Approved for entry into archive by Ronildo Prado (ronisp@ufscar.br) on 2017-04-25T14:19:24Z (GMT) No. of bitstreams: 1 TeseHCN.pdf: 982841 bytes, checksum: bcab3da38d92906a3e65c80c31f92e51 (MD5)
Approved for entry into archive by Ronildo Prado (ronisp@ufscar.br) on 2017-04-25T14:19:34Z (GMT) No. of bitstreams: 1 TeseHCN.pdf: 982841 bytes, checksum: bcab3da38d92906a3e65c80c31f92e51 (MD5)
Made available in DSpace on 2017-04-25T14:28:40Z (GMT). No. of bitstreams: 1 TeseHCN.pdf: 982841 bytes, checksum: bcab3da38d92906a3e65c80c31f92e51 (MD5) Previous issue date: 2016-11-18
Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)
Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
Bundesministerium für Bildung und Forschung (BMBF)
Musculoskeletal risks involving manual box handling can be minimized with the adoption of preventive approaches such as the inclusion of handles in boxes. However, the literature indicates the acquisition of motor skills over working time, can also be a protective factor in development of musculoskeletal disorders. Thus, the study 1 aimed to evaluate the physical load of the upper arms and upper back between 37 novice and 21 experienced subject during handling a new box design compared to commercial ones. The order of surfaces to handle (places to boxes depositions – floor and shoulder levels) and the type of box was randomized. In addition to direct measures (electrogoniometry, inclinometry and electromyography) subjective scales were used to assess the comfort and perceived effort. In general, both experienced and inexperienced subjects had lower biomechanics load handling non-commercial boxes compared to commercial ones. However, the inexperienced subjects demonstrated greater reductions in physical overload during the handling of non-commercial boxes, being more advantageous the recommendation of these boxes for this user profile. In the real work setting, handling boxes is highly rotating mainly in developing countries. Thus, interventions focus on boxes could help the workers, who may have different levels of experience with the job. However, the real work environment involves other tasks besides handling box, and tasks distribution over time could minimize the handling risks. In this way, the study 2 has been proposed to assess the physical exposure in real environment, where in addition to handling box workers perform other activities, aiming to identify the representative handling task in the total work exposure. The biomechanical exposure was assessed from muscular electrical activity of trapezius and upper limb movement recordings during a period of 4 hours to the work routine. The results showed that handling box task required the greater activation of the trapezius in relation to other activities, particularly in peak loads (percentiles 90 and 99 APDF - Amplitude Probability Distribution Function). Effect size calculations have identified the magnitude of the difference between the tasks is large, particularly in peak loads. In relation to the total job, handling box differed by greater amplitudes of upper back forward flexion and left arm elevation postures. Thus, the handling task requires interventions to decrease the physical load in a real work environment in order to promote occupational health, as identified in simulated environment by other studies. The conclusions of this thesis are related to the importance of considering the profile of workers' experience and the need to assessment work exposure involving all tasks performed, emphasizing the importance of studies involving workers in the real working environment.
Os riscos musculoesqueléticos do manuseio de caixas podem ser minimizados a partir da adoção de medidas preventivas, como a inserção de alças em caixas. No entanto, a literatura aponta que a aquisição de habilidades motoras, ao longo do tempo de trabalho, também pode ser um fator protetor no desencadeamento de lesões musculoesqueléticas. Dessa forma, o Estudo 1 teve como objetivo avaliar a carga física dos membros superiores e do tronco superior imposta à 37 sujeitos inexperientes e 21 experientes durante o manuseio de um novo design de caixa, comparado às caixas comerciais. A ordem do ajuste das superfícies onde as caixas foram depositadas (chão e ombro) e da utilização das caixas foi randomizada. Além de medidas diretas (eletrogoniometria, inclinometria e eletromiografia) foram utilizadas escalas para avaliação da agradabilidade e do esforço percebido. Em linhas gerais, tanto os sujeitos experientes como os não experientes apresentaram menor carga biomecânica durante o manuseio das caixas não comerciais comparadas às comerciais. No entanto, os inexperientes demonstraram maiores reduções da sobrecarga física durante o manuseio das caixas não comerciais, sendo mais vantajosa a recomendação dessas caixas para esse perfil de usuário. O contexto real de trabalho, o manuseio de caixas nos países em desenvolvimento é altamente rotativo. Dessa forma, intervenções na caixa poderiam favorecer os trabalhadores, que podem ter diferentes níveis de experiência com o trabalho. No entanto, o ambiente real de trabalho envolve outras tarefas além do manuseio de caixas, e a forma como as tarefas são distribuídas ao longo do tempo poderiam minimizar os riscos do manuseio. Dessa forma, o estudo 2 foi proposto para avaliar a exposição física em ambiente real, onde além do manuseio de caixas os trabalhadores realizam outras atividades, a fim de identificar a representatividade do manuseio na exposição total do trabalho. A exposição foi avaliada a partir do registro da atividade elétrica muscular do trapézio e dos movimentos do membro superior durante um período de 4h da jornada de trabalho. Os resultados demonstraram que o manuseio de caixas exigiu a maior ativação do trapézio em relação às demais atividades realizadas, particularmente nas cargas de pico (percentis 90 e 99 da APDF – Amplitude Probability Distribution Function). Cálculos do tamanho do efeito identificaram que a magnitude da diferença entre as tarefas é grande, principalmente nas cargas de pico. Já em relação ao trabalho total, o manuseio de caixas se diferiu pelas maiores amplitudes da postura de flexão anterior da coluna superior e de elevação do membro superior esquerdo. Dessa forma, o manuseio de caixas requer intervenções para diminuição da sobrecarga física em ambiente real de trabalho, a fim de promover saúde ocupacional, como identificado em ambiente simulado por outros estudos. As conclusões desta tese são referentes à importância de se considerar o perfil de tempo de experiência dos trabalhadores, bem como a necessidade de avaliações da exposição do trabalho envolvendo todas as tarefas realizadas, enfatizando a importância de estudos realizados com trabalhadores e no ambiente real de trabalho.
FAPESP: 2013/04839-5
FAPESP: 2015/12493-7
CNPq: 162324/2012-0

Styles APA, Harvard, Vancouver, ISO, etc.

47

Alhaik, Ghaith. « Influence de l'amidon sur les propriétés rhéologiques, mécaniques et multiphysiques de formulations terre-paille ». Thesis, Artois, 2017. http://www.theses.fr/2017ARTO0205/document.

Texte intégral

Résumé :

Les techniques de l'éco-construction répondent au besoin de réduire l'empreinte environnementale du secteur de la construction grâce à l'utilisation de ressources de proximité (filières courtes), sans transformation énergivore et grâce à la capacité de régulation thermo-hydrique des parois. La terre crue seule ou associée à de la paille fait office de symbole. Mais ses caractéristiques variables selon son origine, le long temps de séchage, et de faibles résistances mécaniques sont des freins à son utilisation. L'association de la terre avec des adjuvants biosourcés, tel que l'amidon déjà utilisé dans la fabrication de plaque de plâtre, représente une voie intéressante d'amélioration des performances. La thèse a pour objectif d'étudier l'influence de l'amidon sur le comportement physico-mécanique de la terre seule ou mélangée à de la paille. L'application envisagée des formules est la préfabrication de produits de construction non-porteurs. Les formulations incluent des fines argilo-calcaires (FAC), de la chènevotte ou des anas de lin, et différents amidons. La première partie de la thèse porte sur les mélanges terre-amidon. Des essais au viscosimètre ont défini le comportement rhéologique des mélanges de type Bingham modifié et ont montré une augmentation de la thixotropie. A l'état durci, les résistances mécaniques ont été meilleures avec l'amidon. La deuxième partie porte sur des mélanges terre-paille-amidon. L'amidon améliore l'ouvrabilité et les résistances mécaniques mesurées selon différentes conditions de stockage. A l'échelle d'un carreau, les performances mécaniques, thermiques, et acoustiques de certaines formules sont comparables à celles de carreaux de plâtre
The eco-construction responds to the need to reduce the environmental footprint in the sector of construction through the use of proximity resources (e.g. earth, straw, etc.), without energy-intensive transformation and through the thermohydric regulation capacity of walls. Raw earth alone or in association with straw is a symbol. But variable characteristics according to its origin, a long drying time and low mechanical strengths are brakes to its use. Earth material in association with biosourced admixtures such as starch, already used in the manufacturing of plasterboard, represents an interesting way to improve its performances.The thesis aims to study the influence of starch on the physico-mechanical behavior of the earth alone or with straw. The intended application of the study is the prefabrication of non-load-bearing construction products. The designed mixes include quarry fines (QF), hemp or flax straw and various starches.The first part of this work deals with earth-starch mixes. Viscometer tests were defined modified Bingham as the rheological behavior of mixes and showed an increase in thixotropy. In hardened state, the mechanical strengths are better with starch.The second part deals with earth-straw-starch mixes. Starch improves the workability and the mechanical strengths measured under different storage conditions. At the scale of a block, the mechanical, thermal and acoustic performances of some mixes are comparable to those of plaster blocks

Styles APA, Harvard, Vancouver, ISO, etc.

48

Lavatura, Giulia. « Valutazione delle pressioni sulle pareti di un silos a fondo piatto contenente materiale granulare durante sisma ». Master's thesis, Alma Mater Studiorum - Università di Bologna, 2011. http://amslaurea.unibo.it/2886/.

Texte intégral

Styles APA, Harvard, Vancouver, ISO, etc.

49

Marchiori, Roberto. « Resistência à corrosão de ferro puro enriquecido superficialmente com cromo, níquel ou titânio, depositados durante a sinterização por plasma ». Florianópolis, SC, 2003. http://repositorio.ufsc.br/xmlui/handle/123456789/85200.

Texte intégral

Résumé :

Dissertação (mestrado) - Universidade Federal de Santa Catarina, Centro Tecnológico. Programa de Pós-Graduação em Ciência e Engenharia de Materiais.
Made available in DSpace on 2012-10-20T16:17:37Z (GMT). No. of bitstreams: 1 195418.pdf: 3250160 bytes, checksum: bd0720428544799c4da15675b5a1ab07 (MD5)
A não satisfatória resistência à corrosão dos materiais obtidos a partir da metalurgia do pó ferrosa, devido à presença de poros residuais, representa uma grande limitação na aplicação desta tecnologia. O tratamento térmico via plasma vem sendo utilizado cada vez mais graças à possibilidade de se trabalhar com gases puros à baixa pressão, o que garante uma atmosfera de alta qualidade, e também pela redução do tempo de processamento através da ativação dos mecanismos de difusão superficial. Esta tecnologia é aplicada também na busca de uma melhoria na resistência à corrosão dos materiais processados, objetivo que pode ser obtido por meio de dois processos distintos: a deposição, concomitante à sinterização, de um elemento mais nobre na superfície do material, e a redução da porosidade superficial pelo bombardeamento de partículas de alta energia, que ativam a difusão atômica na superfície. Neste trabalho estudou-se ambos os processos, efetuando a sinterização em varias configurações. Foram depositados os elementos de liga Ni, Cr e Ti, amplamente usados na diminuição da corrosão. A deposição foi realizada usando atmosfera de 80%Ar-20%H2 a 11500C por 30 e 60 minutos. A redução da porosidade superficial foi obtida utilizando a configuração cátodo, onde a amostra foi colocada a um potencial negativo, sofrendo colisões altamente energéticas pelos íons e as espécies ativas do plasma, fortemente aceleradas na bainha catódica. Foram obtidas as curvas de corrosão das amostras, evidenciando-se a diferença na taxa de corrosão dependendo do tipo de pó utilizado, do elemento depositado e da porosidade superficial. Foi verificada a eficiência na redução da corrosão do Fe devido ao enriquecimento da superfície com um elemento de liga e pela redução da porosidade superficial. Foi aprofundado o estudo da resistência à corrosão das amostras enriquecidas superficialmente com Ni, cujo processo de deposição mostrou-se mais eficiente, e que revelou também os melhores resultados em termo de redução à corrosão.

Styles APA, Harvard, Vancouver, ISO, etc.

50

Soares, Kinglston. « Dispositivo óptico para medida em tempo real da birrefringência de polímeros durante a extrusão ». Universidade Federal de São Carlos, 2010. https://repositorio.ufscar.br/handle/ufscar/685.

Texte intégral

Résumé :

Made available in DSpace on 2016-06-02T19:10:06Z (GMT). No. of bitstreams: 1 3109.pdf: 2004775 bytes, checksum: f5de02186ac0479a6c0ee5621c20735f (MD5) Previous issue date: 2010-03-05
Universidade Federal de Sao Carlos
The main objectives of this project were the development and application of an optical device to measure in real time the flow induced birefringence during the polymer extrusion. The linearly polarized light intensity transmitted through the molten polymer flowing in the slit-die is converted into birefringence via its relation with the optical path difference (OPD). The optical device was calibrated on the bench with the use of polycarbonate sheets with known OPD values. In addition, a methodology was developed to deduct the contribution of the strain birefringence of the transparent glass windows of the Rheophotometer. As flow polymers three polystyrene grades were showsen because of their high flow birefringence. The polymer flow temperature and the slit-die inlet pressure were assessed analyzing their effect in the polymer flow birefringence during extrusion. The results show a good relation with the rheological behavior of the polymer. Increasing the melt temperature there is a reduction in the inlet pressure of the slit-die lowering the birefringence flow values due to the increase of the random molecular motions. Both reduce the intensity of secondary forces that could contribute to the orientation. The greater the feeding rate the higher the chain orientation raising the birefringence values. As polymers are pseudoplastic increases in the shear stress leads to chain orientation in the flow direction. At a constant inlet pressure in the slit-die the higher the molecular weight of the polymer the higher the chain orientation producing higher flow birefringence values. These results do show the good quantitative performance of the optical device developed.
Este projeto teve como principais objetivos o desenvolvimento e aplicação de um dispositivo óptico para medida em tempo real da birrefringência induzida por fluxo durante a extrusão de polímeros. O princípio consiste em medir a intensidade de luz linearmente polarizada transmitida através do polímero sob fluxo e converter este sinal em birrefringência por meio da relação com a diferença de caminho óptico (OPD). O dispositivo óptico foi aferido em bancada com o uso de placas de policarbonato confeccionadas com valores conhecidos de OPD. Além disso, uma metodologia foi desenvolvida para descontar a birrefringência por deformação das janelas transparentes utilizadas no Reofotômetro. Como polímeros de fluxo foram utilizados três tipos de poliestireno, escolhido por ser um polímero que apresenta elevada birrefringência de fluxo. Foram verificadas as influências da temperatura e pressão de entrada do polímero na matriz tipo fenda, local em que as medidas de birrefringência foram realizadas. Os resultados obtidos com o dispositivo óptico proposto mostraram-se coerentes com os fenômenos reológicos ocorridos com o polímero. Desta forma, para o mesmo polímero um aumento da temperatura causou uma diminuição da pressão de entrada na fenda tendo como conseqüência uma queda na birrefringência de fluxo, devido ao aumento dos movimentos aleatórios das moléculas diminuindo a intensidade de interações secundárias que poderiam contribuir para a orientação. Quanto maior a taxa de alimentação maior foi a orientação das cadeias elevando o valor da birrefringência. Como o polímero se comporta como um fluído pseudoplástico, à medida que a tensão de cisalhamento aumenta tem-se um maior alinhamento das cadeias na direção de fluxo, dentro da região de pressão estabelecida. Para polímeros com diferentes massas molares médias foi verificado que para uma mesma pressão de entrada na matriz o polímero de maior massa molar média apresentou maior capacidade de orientação, apresentando um maior valor de birrefringência. Estes resultados comprovam o bom desempenho quantitativo do dispositivo óptico desenvolvido.

Styles APA, Harvard, Vancouver, ISO, etc.

Thèses sur le sujet « Durable materials »

Créez une référence correcte selon les styles APA, MLA, Chicago, Harvard et plusieurs autres