Although the Portuguese diminutive has been analyzed for centuries, there is a lack of descriptive experimental data regarding how native speakers form the diminutive including participants from each state in Brazil. For this study, 1,053 native speakers from each of the 26 states and the federal district of Brazil filled out an online survey, providing information about their age, gender, birth state, and current state of residence in Brazil. Participants selected the form(s) of the diminutive which they would use for 60 test words. Results indicate that the most influential factors in the formation of the diminutive are the age and state of origin of the participant, in addition to the final phone and stress of the word being diminutized. An apparent time shift in diminutive formation is seen in the diminutive endings of -inho and -zinho.

Because of coeliac disease, some individuals cannot tolerate the protein gliadin present in the gluten fraction of wheat flour. From a commercial perspective, there is a need for the development of gluten-free bread with texture and flavour properties similar to the conventional wheat flour loaf. In the context of bread, the gluten component of wheat has a crucial role in stabilising the gas-cell structure and maintaining the rheological properties of the bread. The absence of gluten results in liquid batter rather than pre-baking dough, yielding baked bread with a crumbling texture, poor colour and other post-baking quality defects. The liquid batter cannot be processed on the existing production line of baking industry. The aim is to develop a gluten-free white loaf with similar quality characteristics to that of standard white bread on the existing processing lines at Quality Bakers New Zealand. Within this constraint, dough has to be produced with handling and moulding properties similar to those of conventional wheat flour loaves. This research focused on finding and implementing the gluten substitutes for the development of gluten-free high quality commercial bread. In this research, the independent variables were conventional wheat flour (the most basic control), other gluten-free flours from a variety of sources, starches, supplementary proteins, hydrocolloids such as hydroxypropylmethylcellulose (HPMC), hydrophilic psyllium husk, and enzymes such as microbial transglutaminase, glucose oxidase, lipase and fungal α-amylase. These ingredients were trialled in different combination and composition to produce a dough having ability to trap the carbon dioxide gas during proofing and baking to get high specific volume bread suitable for the Quality Bakers’ product range. After an essentially ‘shotgun’ approach to formulations, the research narrowed to a systematic and progressive variation of ingredients and their composition to develop workable commercial models. Ingredients and their compositions were manipulated according to the outcomes of the trials and their contribution in the formulations. The dependent variables included standard bakery rheological properties based on dough stickiness, dough extensibility, oven spring, bread specific volume, bread slice ability, and bread staling. A gelation system of the lower-temperature-stable hydrocolloid psyllium husk, the heat-stable hydrocolloid hydroxypropylmethylcellulose, maize starch, and potato starch was created to form industrial process able dough having ability to entrap carbon dioxide gas produced during proofing and initial phase of baking. Microbial transglutaminase was used to increase the cross linking of protein present in flours and supplemented for enhancing the dough-like structure and its gas entrapping abilities. A formulation has been discovered by this research for the development of high quality gluten-free commercial bread. The formulated bread has similar quality characteristics to that of standard white bread and can be produced on existing processing lines at Quality Bakers. Industrial process able gluten-free bread with similar quality characteristics to that of standard white bread can be formulated by using a specific combination of soy flour, maize starch, potato starch, yoghurt powder, milk protein, HPMC (K4M), psyllium husk, microbial transglutaminase, lipase, and fungal α-amylase. The significance of this research is mainly commercial and the insights gained may extend to other bakery items that could be used by coeliacs.

Because of coeliac disease, some individuals cannot tolerate the protein gliadin present in the gluten fraction of wheat flour. From a commercial perspective, there is a need for the development of gluten-free bread with texture and flavour properties similar to the conventional wheat flour loaf. In the context of bread, the gluten component of wheat has a crucial role in stabilising the gas-cell structure and maintaining the rheological properties of the bread. The absence of gluten results in liquid batter rather than pre-baking dough, yielding baked bread with a crumbling texture, poor colour and other post-baking quality defects. The liquid batter cannot be processed on the existing production line of baking industry. The aim is to develop a gluten-free white loaf with similar quality characteristics to that of standard white bread on the existing processing lines at Quality Bakers New Zealand. Within this constraint, dough has to be produced with handling and moulding properties similar to those of conventional wheat flour loaves. This research focused on finding and implementing the gluten substitutes for the development of gluten-free high quality commercial bread. In this research, the independent variables were conventional wheat flour (the most basic control), other gluten-free flours from a variety of sources, starches, supplementary proteins, hydrocolloids such as hydroxypropylmethylcellulose (HPMC), hydrophilic psyllium husk, and enzymes such as microbial transglutaminase, glucose oxidase, lipase and fungal α-amylase. These ingredients were trialled in different combination and composition to produce a dough having ability to trap the carbon dioxide gas during proofing and baking to get high specific volume bread suitable for the Quality Bakers’ product range. After an essentially ‘shotgun’ approach to formulations, the research narrowed to a systematic and progressive variation of ingredients and their composition to develop workable commercial models. Ingredients and their compositions were manipulated according to the outcomes of the trials and their contribution in the formulations. The dependent variables included standard bakery rheological properties based on dough stickiness, dough extensibility, oven spring, bread specific volume, bread slice ability, and bread staling. A gelation system of the lower-temperature-stable hydrocolloid psyllium husk, the heat-stable hydrocolloid hydroxypropylmethylcellulose, maize starch, and potato starch was created to form industrial process able dough having ability to entrap carbon dioxide gas produced during proofing and initial phase of baking. Microbial transglutaminase was used to increase the cross linking of protein present in flours and supplemented for enhancing the dough-like structure and its gas entrapping abilities. A formulation has been discovered by this research for the development of high quality gluten-free commercial bread. The formulated bread has similar quality characteristics to that of standard white bread and can be produced on existing processing lines at Quality Bakers. Industrial process able gluten-free bread with similar quality characteristics to that of standard white bread can be formulated by using a specific combination of soy flour, maize starch, potato starch, yoghurt powder, milk protein, HPMC (K4M), psyllium husk, microbial transglutaminase, lipase, and fungal α-amylase. The significance of this research is mainly commercial and the insights gained may extend to other bakery items that could be used by coeliacs.

Weirs are commonly used as spillways to release flows from a reservoir. The free-falling jet on the downstream side of the weir is called the nappe. Under certain hydraulic conditions, determined mainly by the size, design, and construction of the weir, nappe oscillation, otherwise known as nappe vibration, can occur. Characteristics of this dynamic behavior include excessive acoustic energy manifested as sound pressure waves and lowfrequency noise accompanied by horizontal waves or banding on the nappe. Mitigation of this process may be required, especially if the weir operates in close proximity to occupied structures. Instability of water jets moving through air has been a topic of study for over a century, although studies specific to curvilinear weir nappe flow are less common. The objective of this research is to further the understanding related to the mechanisms that cause nappe vibration, document the occurrence conditions, and investigate mitigation techniques. Research was conducted at the Utah Water Research Laboratory (UWRL) using three physical models: A 6 ft wide x 3.5 ft tall weir with a quarter round crest (model #1) A 15.4 ft wide x 11 ft tall weir with a broad crest (model #2) A 16 ft wide x 12 ft tall weir with a quarter round crest (model #3) Testing included confined and unconfined nappe conditions (open air cavity behind the nappe vs. closed air cavity) for model #1 and model #3. Vibration frequencies were recorded and analyzed using an accelerometer and microphone. Comparisons were made between the three models of different scale. Testing included modifications to the weir crest and the weir apron to study the effect on the behavior of the nappe. The results of this study are presented, including a review of previous literature and theories. The mechanisms that sustain and amplify the nappe vibration phenomenon varied at the different size-scales, while evidence exists that the root cause of initial instability leading to self-induced vibration can be traced to the same source. The results of this study should be of practical use to engineers, researchers, and those concerned with dam safety.

Using a multi-scale experimental approach, the research undertaken in this thesis investigated the role of the flood pulse in ephemeral floodplain wetlands of the River Murray, in order to better understand the impact of river regulation (and permanent inundation) on these wetlands. An ecosystem-based experiment was conducted on the River Murray floodplain, to compare changes in nutrient availability and phytoplankton productivity in three ephemeral wetlands (over a drying/reflooding cycle) with three permanently inundated wetlands. In the ephemeral wetlands, both drying and re-flooding phases were associated with significant increases in nutrient availability and, in some cases, phytoplankton productivity. It was demonstrated that the ?flood pulse?, as described by the Flood Pulse Concept (FPC), can occur in ephemeral wetlands in dryland river-floodplain systems, although considerable variation in the nature of the pulse existed amongst these wetlands. Results of this experiment suggest that factors such as the degree of drying and length of isolation during the dry phase, the rate of re-filling, timing of re-flooding and the number of drying/re-flooding cycles may be potentially important in producing the variation observed. Permanent inundation of ephemeral wetlands effectively removed these periods of peak nutrient availability and phytoplankton productivity, resulting in continuously low levels (of nutrient availability and phytoplankton productivity). It was concluded that alteration of the natural hydrological cycle in this way can significantly reduce nutrient availability, primary production and secondary production, essentially changing the structure and function, the ecology, of these wetlands. Equally, the results of this experiment indicate that some of the changes resulting from river regulation and permanent inundation can be somewhat reversed, within a relatively short period of time, given re-instatement of a more natural hydrological regime. A mesocosm experiment was used to examine the influence of the dry phase, specifically the effect of the degree of wetland drying, on patterns of nutrient availability and primary productivity comprising the flood pulse. Compared to permanent inundation, re-flooding of completely desiccated sediments increased carbon (C) and nitrogen (N) availability while partial drying generally decreased, or had little effect on, C and N availability after re-flooding. However, degree of drying had little effect on phosphorus availability or rates of primary production measured after re-flooding, and it is possible that these two factors are related. Partial drying reduced rates of community respiration after reflooding, possibly a reflection of the reduced carbon concentrations measured in these mesocosms in this phase of the experiment. Degree of drying also influenced the macrophyte community (measured after three months of flooding), with plant biomass generally decreasing and species diversity increasing as the degree of drying increased (with the exception of complete sediment desiccation which had lasting negative effects on both macrophyte biomass and species diversity). The results of the ecosystem and mesocosm experiments were utilised, in addition to results collected from the same experiment conducted at two smaller scales (minicosms and microcosms), to assess whether the effects of hydrological regime on nutrient availability at the ?wetland? scale could be replicated in smaller-scale experiments. None of the smaller-scaled experiments included in this investigation were able to replicate the specific response to hydrological regime recorded at the ecosystem scale, however the mesocosm experiment did produce results that were more similar to those at the ecosystem scale than those produced by the mini and microcosm experiments. The results of this study indicated that extrapolation of results from small-scale experiments should be undertaken with caution, and confirmed that a multi-scale approach to ecological research is wise, where large-scale field experimentation and/or monitoring provides a check on the accuracy, and hence relevance, of conclusions reached via mesocosm experiments.

L’objectif de cette thèse était d’étudier suivant deux approches la dégradation des polydiméthylsiloxanes. L’approche expérimentale a permis d’étudier les mécanismes de rupture de chaîne et les phénomènes de réticulation du polymère lorsque ce dernier est soumis à des conditions de thermo-oxydation ou de photo-oxydation comparables à celles du vieillissement naturel. La seconde partie propose de modéliser les résultats expérimentaux par un modèle cinétique issu des calculs ab initio. L’exploitation in vitro de la dégradation du polymère a permis de mettre en évidence la formation de monoxyde de carbone et de dioxyde de carbone, ceux-ci jouant le rôle de révélateurs de rupture de liaison Si-CH3. Toutefois le comportement des PDMS sur des temps de dégradation plus importants montre clairement la formation d’oligomères cycliques par dépolymérisation de la chaîne macromoléculaire. Parallèlement la photo-oxydation de ces polymères entraîne la formation de réseaux multidimensionnels qui traduisent des phénomènes de réticulation avec formation d’acide formique. Cette étude a permis de montrer que la dégradation des PDMS, dans des conditions de vieillissement naturel, procède de deux mécanismes antagonistes, l’un favorisant la réticulation du polymère et le second sa dépolymérisation. La seconde partie de ce travail s’intéresse aux mécanismes de formation des oligomères cycliques observés expérimentalement lors de la dégradation des PDMS. Des réponses précises ont pu être amenées grâce à une analyse théorique détaillée de la constante de cyclisation de ces polymères. Cette étude nous a permis de montrer le rôle essentiel du couplage des rotateurs internes dans le calcul de la constante de cyclisation en fonction de la taille des cycles obtenus. Nos résultats théoriques reproduisent avec exactitude l’évolution de la courbe de la constante de cyclisation observée expérimentalement pour des cycles de taille inférieure à 20 motifs, à savoir un maximum global pour des cycles constitués de quatre motifs et un minimum local pour des cycles à dix motifs. Nous avons démontré que l’origine de l’évolution oscillatoire de la constante de cyclisation traduisait le changement de caractère de certains degrés de liberté entre des vibrations pures (petits cycles) et des rotations empêchées (cycles de plus grande taille). / This work aimed at investigating the degradation pathways of polydimethylsiloxanes through two perspectives. The experimental approach studied bond scission and cross-linking degradation mechanisms when the polymer is exposed to thermo- or photo-oxidation conditions that are similar to that of the natural ageing. In the second part, the experimental results are modeled with a theoretical kinetic model, based on ab initio calculations.The in-vitro study of the polymer degradation showed that formation of carbon monoxide and carbon dioxide were by-products of Si-CH3 bond scissions. However, the degradation of PDMS for longer time periods showed clearly the formation of cyclic oligomers obtained through depolymerization of the macromolecule. In parallel, the photo-oxidation conditions yielded the formation of multidimensional cross-linked networks and formation of formic acid. This study showed that in the natural conditions, the degradation of PDMS proceeded through two opposite mechanisms, one that produced cross-linked networks while in the other, depolymerization was favored. In the second part, we investigated the mechanisms of the formation of cyclic oligomers that were observed experimentally during the degradation of the polymer. A detailed theoretical model was built in order to reproduce the dependence of the experimental cyclization constant with cycle size. This study showed the key role of the coupling in the treatment of hindered rotors. Our theoretical results reproduced accurately the oscillatory behavior of the cyclization constant for cycle sizes less than 20-mers, namely the global maximum for the 4-unit cyclic oligomers, and the local minimum for cycle sizes of 10 units. We have also shown that the origin of the oscillatory behavior of the cyclization constant revealed that some degrees of freedom underwent specific character transformation between a pure vibration for small cycles and hindered rotation for larger ring sizes.

Scientific stratospheric balloons offer a valuable service to scientists wishing to test or demonstrate developing technological instruments, or to run fully operational instruments with short preparation times and for a cheap price compared to other similar services. The ballooning industry is therefore a vital part of the scientific community as it enables less funded and experienced scientific organisations to actively engage in the development of their technologies. In the context of scientific stratospheric balloons, the speed of permeation affects among other things the flight time and the flight planning, as these are determined by the rate of loss of the buoyancy force keeping the balloon afloat. Most balloons today use helium as lifting gas, but the ballooning industry is today facing increased pressure to switch to hydrogen gas. Before making this switch, understanding how hydrogen gas behaves differently, in terms of permeation or otherwise, is important to prevent unexpected flight paths among other things. In this thesis, two experiments were conducted in order to attempt to determine the ratio of permeation speed between hydrogen gas and helium through balloon membranes. One experiment used a manometric method, where the pressure of permeant in a diffusion chamber was measured over time. The other experiment measured the buoyancy force of permeant-filled balloons over time. The resulting ratio of permeation speed may give more confidence in predicting how much faster or slower a stratospheric balloon filled with hydrogen will lose buoyancy force.

La recherche que nous avons menée s'inscrit dans les projets de l'équipe de recherche Maths à Modeler. En particulier dans celui portant sur les situations de recherche en classe (Grenier et Payan, 2002 ; Ouvrier-Buffet, 2003 ; Godot, 2005 ; Cartier, 2008). Cette étude est centrée sur la démarche de recherche en mathématiques et plus particulièrement sur le rôle de l'expérimental. Un des postulats fondateur de notre recherche est que savoir faire des mathématiques, c'est savoir résoudre partiellement des problèmes de recherche, la résolution de tels problèmes nécessitant de passer par des phases expérimentales. Notre problématique porte donc sur la transmission aux élèves du savoir-faire « démarche expérimentale en mathématiques » et sur le rôle que celui-ci joue dans la résolution de problèmes de recherche. Considérant que ce savoir-faire ne peut s'apprendre qu'à travers sa pratique en situation de résolution de problèmes, l'objectif de notre recherche a été la détermination de conditions épistémologiques et didactiques favorisant la mise en pratique de la « démarche expérimentale ». En plus de la construction d'un modèle de situation pour la « démarche expérimentale », nous avons construit, analysé et expérimenté des situations se référant à ce modèle. Pour mener à bien notre étude, nous avons utilisé le modèle de situation de recherche pour la classe (Grenier et Payan, 2002 ; Godot, 2005), ainsi que des éléments de la théorie des situtions didactiques de Brousseau (1998), en particulier validation a-didactique, contrat didactique et milieu. Nous avons aussi défini un modèle de « démarche expérimentale en mathématiques » qui a servi de référant à notre recherche. Après avoir observé que la « démarche expérimentale en mathématiques », telle que nous l'entendons, n'est pas proposée par l'institution scolaire, les expérimentations et les analyses, que nous avons menées, ont montré que, dans une certaine mesure, il est possible de la faire pratiquer à des élèves. De plus, cette pratique a permis aux élèves de progresser dans la résolution grâce à un enrichissement des conceptions qu'ils portaient sur le problème à résoudre. Ces expérimentations nous ont aussi permis d'affiner les situations que nous avons construites. / This research fits into the projects of the Maths à Modeler research team, especially in the one about Research Situation for the Classroom (Grenier and Payan, 2002 ; Ouvrier-Buffet, 2003 ; Godot, 2005 ; Cartier, 2008). One of our founding postulate is that knowing how to do mathematics is knowing how to solve partially reserch problems, the solving of such problems requiring experimental phases. Our problematic is about the teaching of the knowledge "experimental approach in mathematics" and the role that this knowledge plays in solving research problems. As we consider that this knowledge can only be learned by its practise, the aim of our research is the identification of epistemological and didactical conditions favouring the practise of the experimental approach in mathematics. Along with the building of a model of "situations" for the experimental approach, we built, analysed and experimented situations which refer to the model. We used the model of Research Situation for the Classroom (Grenier and Payan, 2002 ; Godot, 2005) and elements of the theory of didactical situation (Brousseau, 1998), especially a-didactical validation, didactical contract and "milieu". We have also defined a model of "experimental approach in mathematics" which was used as a "guide" of our research. After observing that "the experimental approach in mathematics", as we defined it, is not proposed by schools, experimentations and analyses showed that, in a certain way, students can do experimental approach in mathematics. Moreover, this practise let students progress in finding solutions thanks to the improvement of their conceptions about the problem. These experimentations also let us refined the situations that we have built.

Pour les structures en bois comme pour les autres techniques de construction, les planchers jouent un rôle important dans le comportement global d’un bâtiment soumis à une sollicitation sismique. En plus de la reprise des efforts verticaux, ces planchers assurent le transfert des efforts horizontaux vers les murs de contreventement (fonction diaphragme). Pour cette fonction, le plancher peut être assimilé à une poutre courte disposée horizontalement et supportée par plusieurs appuis semi-rigides (murs de contreventement). En conséquence, la distribution des efforts sur les murs de contreventement est directement liée au rapport entre leurs raideurs et celle du plancher dans son plan.Les planchers en bois traditionnels sont généralement composés par une poutraison (des solives, des entretoises et des poutres de chaînage) et une surface plane composée d’une juxtaposition de panneaux. La connexion panneaux-poutraison est généralement réalisée par des clous. Le dimensionnement de ces planchers est souvent piloté par les charges verticales et les caractéristiques mécaniques dans le plan sont rarement contrôlées.Le comportement mécanique des planchers diaphragmes en bois est peu étudié dans la littérature. La présente thèse aborde ce comportement en s’appuyant sur trois approches : analytique, numérique (M.E.F.) et expérimentale. L’approche analytique s’inspire de celle utilisée par les codes de calcul sismique nord-américains. La modélisation numérique prend en compte la configuration géométrique réelle des diaphragmes ainsi que les effets non-linéaires matériels et géométriques. Deux types de modèles numériques sont proposés : « détaillé » et « simplifié ». Le modèle détaillé, utilisant des éléments de poutres et de coques, permet d’étudier la distribution des contraintes internes au sein du plancher. Le modèle simplifié, moins coûteux, s’appuie sur des éléments poutres et barres. Il permet de réaliser des analyses de sensibilité et il peut être utilisé dans des analyses de structures avec géométries complexes.Une campagne expérimentale est conduite sur des planchers en bois. Deux planchers (2,4x7,2m2), avec et sans entretoises, sont testés en flexion dans leur plan. Une instrumentation riche composée de capteurs de déplacement, d’inclinomètres et d’un système de mesure sans contact, sont utilisés pour suivre le comportement de ces planchers aux niveaux global et local. Les observations expérimentales montrent un comportement fortement non-linéaire avec une influence importante des entretoises sur la raideur et la résistance. La rupture des panneaux est due à la flexion à mi portée ou à la compression près des angles en contact. La comparaison avec les résultats expérimentaux a permis de valider les modèles numériques développés. Ces modèles révèlent une forte participation de la connexion panneaux-poutraison aux comportements mécaniques des planchers aux niveaux global et local.Le modèle numérique simplifié est utilisé pour mener une étude de sensibilité des planchers avec trémies. Ainsi, treize configurations de planchers sont analysées en vue d’identifier les positionnements les plus défavorables des trémies. Par ailleurs, l’application du modèle analytique montre qu’il représente correctement la phase linéaire du comportement des planchers qui est un paramètre utilisable dans les analyses à l’état limite de service. Les résultats numériques et expérimentaux obtenus constituent une bonne base pour étendre le domaine d’application du modèle analytique. / In timber structures as other, floors play an important role in the overall behaviour of a building subjected to seismic loading. In addition to the vertical forces, these floors transfer horizontal forces to the shear walls (diaphragm function). For this function, the floor can be considered as a short beam placed horizontally and supported by semi-rigid supports (shear walls). Therefore, the force distribution on the shear walls is directly related to the in-plane stiffness ratio between floors and shear walls.Traditional wooden floors are usually composed by joists framing (joist, struts, chords beams) and a surface made by juxtaposed panels. The panel-joist framing connection is usually made by nails. Size of the floors elements is often driven by the vertical loads, thus mechanical properties in the plane are rarely checked.The in-plane behaviour of timber floor is poorly studied in the literature. This thesis studies this behaviour using three approaches: analytical, numerical (FEM) and experimental. The analytical approach is based on that used in North American codes of seismic design. Numerical models take into account the actual geometry of the timber diaphragms and nonlinear effects (material and geometric). Two types of numerical models are proposed: "detailed" and "simplified". The detailed model, based on beams and shell elements, allows studying the distribution of internal stresses in the floor. The simplified model uses beams and bar elements. It allows carrying out sensitivity analysis and can be used to study complex geometries of floors.An experimental campaign is conducted on timber floors. Two floors (2,4 x7,2m2), in blocked or unblocked configuration, are tested in bending in their plane. Displacement transducers, inclinometers and a camera measuring system are used for monitoring the behaviour of floors at global and local levels. The experimental observations show a highly nonlinear behaviour with a significant influence of struts on the stiffness and strength. Panels failure due to bending and compression in the corners were observed. The comparison between experimental and numerical results allows validating the numerical models. These models show a significant participation of the panels-joist framing connection on the global and local mechanical behaviour of floors.The simplified model is used to conduct a sensitivity analysis of floors with hoppers. Thirteen floors configurations are analyzed to identify the most unfavourable configurations of hoppers position. Furthermore, the analytical model represents well the linear phase of floors behaviour. The numerical and experimental results obtained provide a good basis to expand the scope of the analytical model. / Tanto en las estructuras de madera como en otras técnicas de construcción, las losas juegan un importante rol en el comportamiento global de un edificio sometido a una solicitación sísmica. Además de las cargas verticales, las losas deben transmitir las cargas horizontales hacia los muros de corte (función diafragma). En esta función, la losa puede ser tratada como una viga corta puesta horizontalmente y apoyada sobre soportes semi-rígidos (muros de corte). En consecuencia, la distribución de fuerzas entre los distintos muros de corte es determinada por la relación de rigidez entre estos muros y la losa.Las losas tradicionales de madera son generalmente compuestas por un envigado (vigas transversales, canes o separadores, vigas periféricas) y una superficie construida con paneles yuxtapuestos. La conexión entre los paneles y el envigado es generalmente realizada con clavos. El dimensionamiento de estos elementos es habitualmente determinado por las cargas verticales, de esta manera las propiedades mecánicas en el plano de estas losas, son raramente controladas.El comportamiento mecánico de los diafragmas de madera ha sido poco estudiado en la literatura. Esta tesis aborda este comportamiento a partir de tres enfoques: analítico, numérico (Elementos Finitos) y experimental. El método analítico considerado se basa en las ecuaciones propuestas por los códigos de diseño sísmico norteamericanos. La modelización numérica tiene en cuenta la configuración geométrica real de las losas y los efectos no-lineares de origen material y geométrico. Dos tipos de modelos numéricos son propuestos: "detallado" y "simplificado". El modelo detallado, es construido a partir de elementos finitos de tipo vigas y planos. Este modelo es utilizado principalmente para estudiar la distribución de esfuerzos internos en las losas. El modelo simplificado, construido a partir de elementos de vigas y barras, es utilizado para conducir análisis de sensibilidad.Un estudio experimental sobre losas de madera es presentado. Dos losas (2,4 x7, 2m2) con y sin separadores son testeadas en flexión en su plano. Un sistema de instrumentación compuesto por transductores de desplazamiento, inclinómetros y videocámaras, fueron utilizados para monitorear el comportamiento global y local de las losas. Las observaciones experimentales muestran un comportamiento altamente no-lineal con una fuerte influencia de los separadores sobre la rigidez y resistencia de la estructura. Los modos de ruptura observados corresponden a la ruptura de paneles en flexión y a la compresión local debido a transmisión de esfuerzos por contacto. La comparación de resultados experimentales y numéricos permite validar los modelos propuestos. Estos modelos muestran una fuerte participación de la conexión paneles-envigado sobre el comportamiento mecánico global y local de las losas.El modelo numérico simplificado es utilizado para llevar a cabo un análisis de sensibilidad de losas con aberturas de escalera. Trece configuraciones de losas son analizadas para identificar la posición de abertura más desfavorable. Por otra parte, el modelo analítico representa correctamente el comportamiento de las losas en fase lineal. Los resultados numéricos y experimentales obtenidos proporcionan una buena base para ampliar el dominio de aplicación de este modelo analítico.

Submitted by Renata Lopes (renatasil82@gmail.com) on 2018-11-19T14:40:48Z No. of bitstreams: 1 wagnerdiasrocha.pdf: 3693391 bytes, checksum: ff882b197689decbd93b1281b5bf0dd5 (MD5) / Approved for entry into archive by Adriana Oliveira (adriana.oliveira@ufjf.edu.br) on 2018-11-23T13:04:01Z (GMT) No. of bitstreams: 1 wagnerdiasrocha.pdf: 3693391 bytes, checksum: ff882b197689decbd93b1281b5bf0dd5 (MD5) / Made available in DSpace on 2018-11-23T13:04:01Z (GMT). No. of bitstreams: 1 wagnerdiasrocha.pdf: 3693391 bytes, checksum: ff882b197689decbd93b1281b5bf0dd5 (MD5) Previous issue date: 2018-08-21 / Este trabalho apresenta uma proposta de abordagem experimental para o Efeito Fotoelétrico baseada em um kit didático capaz de demonstrar a ocorrência (ou não) do fenômeno em função da variação de intensidade e de frequência da luz incidente sobre um material receptor. O principal objetivo é fornecer uma alternativa diferenciada para a construção do conhecimento sobre o assunto. O kit, elaborado com LEDs e outros componentes de baixo custo presentes no cotidiano, é de fácil reprodução e operação, além de compacto o suficiente para viabilizar a execução de atividades práticas em qualquer sala de aula, sendo assim muito útil principalmente para alunos e professores do Ensino Médio, os quais muitas vezes não dispõem de laboratórios e equipamentos, seja pela restrição de acesso ou até mesmo pela inexistência destes. Com três aplicações em sala de aula, desenvolveu-se uma metodologia onde duas hipóteses excludentes entre si e que se apresentam como explicação para o fenômeno são confrontadas experimentalmente. A validade de somente uma dessas hipóteses é comprovada pelas respostas dadas a dois questionamentos pós-atividade. Os resultados obtidos demonstram que os alunos conseguiram compreender o funcionamento do kit, utilizá-lo para realizar a atividade proposta e construir eles próprios o seu conhecimento sobre o assunto. Além disso, as críticas e sugestões coletadas ao final do processo demonstram que houve uma aceitação considerável da proposta pelos mesmos. A fim de torná-la acessível aos professores de Física interessados na sua utilização, são fornecidos adicionalmente dois roteiros, sendo que um descreve passo a passo a montagem do kit e o outro dá suporte à execução da atividade experimental proposta. / This work presents a proposal for an experimental approach to the Photoelectric Effect based on a didactic kit capable of demonstrating the occurrence (or not) of the phenomenon as a function of the variation of intensity and frequency of light incident on a receiving material. The main objective is to provide a differentiated alternative for building knowledge about the subject. The kit, made with LEDs and other low-cost components present in everyday life, is easy to reproduce and operate, and compact enough to enable the execution of practical activities in any classroom, and is therefore very useful mainly for students and teachers of secondary education, which often do not have laboratories and equipment, either by the restriction of access or even by the lack of them. With three applications in the classroom, a methodology was developed where two mutually exclusive hypotheses that present themselves as an explanation for the phenomenon are confronted experimentally. The validity of only one of these hypotheses is proven by the responses given to two post-activity questions. The obtained results demonstrate that the students were able to understand the operation of the kit, use it to carry out the proposed activity and build their own knowledge about the subject. In addition, the criticisms and suggestions collected at the end of the process demonstrate that there has been considerable acceptance of the proposal by the parties. In order to make it accessible to physics teachers interested in its use, two scripts are additionally provided, one describing step by step the assembly of the kit and the other supporting the execution of the proposed experimental activity.