Den här undersökningen belyser hur makt kan manifesteras i bild. Den utgår från maktteorier, främst postmodern maktanalys enligt Michel Foucault och hans uttolkare. Semiotisk bildanalys används för att belysa maktmanifestationer i ett bildmaterial som huvudsakligen utgörs av fotografier tagna av författaren. Resultatet presenteras i en gestaltning där bilderna visas tillsammans med en analys av varje bild. Tekniker såsom perspektivval, bildutsnitt och efterbehandling, för att förändra en bilds konnotation, demonstreras. Olika maktperspektiv och makttekniker urskiljs och särskilt fokus läggs på mindre uppenbara maktyttringar och dolda maktuttryck, t.ex. osynliggörande, obstruktion, belöning och övervakning. Här konstateras att uttryck för makt inte är absoluta och odiskutabla utan att konnotationen är beroende av betraktarens kultursfär, tidigare erfarenheter och kunskap. En diskussion förs om uttolkningen av de maktteoretiska och semiotiska begreppen och hur vida definitionerna kan vara för att analysen ska vara användbar och meningsfull. / This study illustrates how power can be manifested in the image. It is based on theories of power, mainly postmodern power analysis according to Michel Foucault and his interpreters. Semiotic analysis is used to illustrate the manifestations of power in the visual material that mainly consists of photographs taken by the author. The results are presented in a display where the images are shown along with an analysis of each image. Techniques such as perspective, composition and finish, in order to change the connotation of an image, are being demonstrated. Different perspectives of power and power techniques are distinguished and a special focus is put on the less obvious manifestations of power and the hidden expressions of power, for example inattention, obstruction, reward and monitoring. It is found that expressions of power are not absolute and indisputable and that the connotation depends on the viewer's culture sphere, previous experience and knowledge. A discussion is being held about the interpretation of the power theoretical and semiotic concepts and how wide the definitions can be for the analysis to be useful and meaningful.

Breeding programmes that use elite sires with the best estimated breeding values for muscling traits have achieved significant improvement in lamb production in the UK. Further acceleration of the rate of genetic gain for the desirable production traits could be achieved using DNA marker-assisted selection (MAS) breeding strategies. The underlying causal genetic variants associated with improved muscling may be unknown and lying between a cluster of genes known as quantitative trait loci (QTL) or could be single nucleotide polymorphisms (SNP). LoinMAXTM, Texel muscling QTL (TM-QTL) and c.*1232G > A myostatin mutation were genetic variants that reported to be associated with improved muscling characteristics and hence subjected to further analysis in this project. It is essential before incorporating segregating genetic variants in any breeding scheme to comprehensively evaluate their effects on carcass traits. In-vivo scanning (ultrasound scanning (US) and computed tomography scanning (CT)), and carcass video image analyses (VIA) were used in the current studies. Objective VIAprediction weights of the carcass primal cuts could be the backbone of a value-based marketing system that is suggested to replace the current Meat and Livestock Commission (MLC) carcass grades for conformation scores (MLC-C) and fat class (MLC-F). The effect of a single copy of LoinMAXTM QTL (LM-QTL) compared to noncarriers was evaluated in UK crossbred lambs out of Scottish Mule ewes. M. longissimus lumborum (MLL) width, depth and area, as measured by CT scanning, were significantly greater in lambs heterozygous for LM-QTL compared to noncarriers. VIA detected a significant effect of the LM-QTL on the predicted weight of saleable meat yield in the loin primal cut (+2.2%; P < 0.05). The effects of the ovine c.*1232G > A myostatin mutation (MM), found on sheep chromosome 2, on carcass traits in heterozygous crossbred lambs sired by Texel and Poll Dorset rams were studied. Texel crossbred lambs carrying MM had increased loin depth and area. In both crossbred lambs, MM-carriers had significantly higher CT-estimated lean weight and proportion (2 to 4%) and muscle to bone ratios (by ~3%). Poll Dorset heterozygous crossbred animals had higher muscle to fat ratio (28%) and significantly lower fat-related measurements. The c.*1232G > A (MM) mutation as well as TM-QTL effects were evaluated in a different genetic background of Texel x Welsh Mountain crossbreed lambs. Carrying two copies of MM was associated with a significant positive effect on 8 week weight, a negative effect on ultrasound fat depth, a substantial decrease in MLC-fat score, positive impact on VIA-estimated weight of the hind leg, chump and loin primal cuts, as well as the muscularity of the hind leg and loin regions with greater loin muscle width, depth and area. Two copies of MM altered lambs‟ morphological traits with significantly wider carcasses across the shoulders, breast and hind legs and greater areas of the back view of the carcass when measured by VIA. TM-QTL significantly increased US-muscle depth and TM-QTL carriers had significantly greater loin muscle width and area measurements. Comparing TM-QTL genetic groups (homozygote allele carriers (TM/TM), heterozygote carriers of paternal and maternal origin of allele (TM/+ and +/TM, respectively) and homozygote non-carriers (+/+)) and TM-QTL mode of action were then studied. TM/TM carcasses were significantly heavier than non-carriers by 1.6 kg and scored higher conformation values when compared to heterozygote groups only. TM/+ lambs had significantly higher VIA-predicted weight and muscularity in the hind leg and loin, and higher loin dimensions relative to some other genotypic groups. The effect of TM-QTL on some carcass shape measurements was significant. TM-QTL mode of action results on the loin muscling traits supports the earlier reports of polar over dominance. In the light of growing calls to replace the current subjective carcass payment system with the objective VIA system that values the carcass according to the superiority of its cuts, I investigated the ability of US and CT measurements to predict the VIAestimated weights of the carcass primal cuts. Several prediction equations were examined but the best could be achieved when ultrasound measurement, CT linear measurements and live weight were fitted in the model. Since CT scanning information of elite sires is now being used for genetic selection for carcass merit, genetic parameters and genetic relationships between CT scanning measurements and post mortem traits (VIA and MLC-FC) were estimated. However, results were not sufficiently accurate to be of practical use due to lack of data.

Les THTZ (réfractaires électrofondus à Très Haute Teneur en Zircone) sont des matériaux utilisés pour la construction de fours verriers. Ils sont composés d'un squelette dendritique de zircone imprégné de phase vitreuse. Cette étude, qui fait partie du programme national de recherche NOREV (Nouveaux REfractaires Verriers), financé par l'ANR (Agence Nationale pour la Recherche), vise à étudier les influences de la morphologie tridimensionnelle de la microstructure et des propriétés des phases sur le comportement mécanique du THTZ, en particulier pendant la transformation quadratique-monoclinique qui intervient lors du refroidissement post-coulée. Les microstructures 3D de différents matériaux ont été investiguées par tomographie X à l'ESRF (synchrotron de Grenoble). Les images 3D segmentées ont donné lieu à des analyses d'images permettant de caractériser la topologie microstructurale des matériaux, à travers de mesures de covariance, de tortuosité et de percolation. Une relation entre la vitesse d'attaque par l'acide fluorhydrique (HF) et la densité de surface du squelette de zircone a été identifiée. En segmentant le squelette de zircone par la méthode des bassins versants (watershed), nous avons pu comparer le niveau de connectivité du réseau de zircone des différents matériaux. Les résultats sont corrélés avec les calculs numériques de la rigidité microstructurale du squelette des matériaux. Après attaque acide et à haute température, un phénomène de flexibilité a été observé sur des éprouvettes minces et a pu être mis en relation avec la connectivité des matériaux. Les mesures de dilatation lors de cycles thermiques ont mis en évidence les effets induits par l'ajout d'yttrine. La phase vitreuse joue un rôle important pendant la transformation de quadratique à monoclinique, en limitant l'endommagement microstructural des matériaux. Le THTZ dopé par l'ajout de 7% d'yttrine présente des propriétés très différentes des autres matériaux : il est plus rigide et ne subit plus la transformation martensitique. Des calculs par éléments finis tridimensionnels, réalisées à partir de volumes élémentaires de la microstructure réelle, ont permis d'estimer l'influence des propriétés des phases constituantes, de leur morphologie et des conditions aux limites sur la contrainte interne responsable de l'endommagement microstructural. / Zirconia-Rich Fused-Cast Refractories are largely used in industry to build glass furnaces. This kind of refractory is composed of two phases: a dendritic skeleton of zirconia surrounded by a glassy phase which represents about 12% in volume. This work aims to evaluate the influences of the 3D microstructural morphology and of the properties of the constituting phases on the mechanical properties of materials, especially during the transformation from tetragonal to monoclinic which occurs during cooling-down after casting. This work is part of the NOREV (New refractories for glass furnaces) project funded by the French ANR (National Agency for Research). 3D pictures of the microstructures have been obtained owing to X-ray microtomographies performed at ESRF (European Synchrotron Radiation Facility, Grenoble, France). After segmentation, these images allowed the microstructural topology of materials to be investigated, using image analysis and mathematical morphology parameters like covariance, tortuosity and percolation. A relationship between the surface density of the zirconia skeleton and its dissolution kinetics in hydrofluoric acid (HF) solution has been identified. Segmenting the skeleton using the watershed method allowed the connectivities of the different materials to be compared. The results are correlated with the numerical calculations of the microstructure stiffness. A phenomenon of flexibility of the zirconia skeleton has been observed on thin specimens, at high temperature and at room temperature, when the glassy phase has been removed. This phenomenon is related to the connectivity and to the “puzzle-like” structure of the zirconia skeleton. Dilatometric measurements revealed the effects of yttrine addition. The glassy phase exhibits a very important role in the t-m transformation, while limiting microstructural damage of materials. The refractory containing 7% yttrine revealed properties totally different from other materials: its stiffness is higher and it does not experience the t-m transformation. 3D finite element simulations have been carried out on elementary volumes of the actual microstructure of the materials. The influences of the properties of the constituting phases, of the microstructural morphology and of the boundary conditions, which are responsible for the microstructural damage during cooling down, could then be estimated.

La mise en œuvre des préimprégnés unidirectionnels à fibre de carbone et résine époxyde est une étape fondamentale pour la conception de pièces structurales aéronautiques. Elle influe directement sur la qualité de la pièce et notamment sur la quantité de défauts poreux qu’elle renferme. Ainsi, deux phénomènes de création de la porosité ont été identifiés expérimentalement : l’un mécanique, l’autre thermodynamique. Une fois créés, ces défauts peuvent être extraits hors de la pièce si le marouflage et le cycle de polymérisation favorisent cette évacuation gazeuse. Les effets sur la porosité de la température et de la pression imposées pendant la réticulation de la résine sont modélisés en prenant en compte les phénomènes thermo-diffuso-mécaniques entre la résine et la bulle de gaz. Un protocole expérimental reposant sur l’analyse d’image a été développé afin de quantifier le plus précisément possible le taux volumique de porosité, ainsi que leurs tailles et leurs localisations. / Long fiber reinforced epoxy matrix composite laminate manufacturing process is divided into several stages. The most critical one is the polymerization stage. If not optimized, defects in the bulk material such as voids can occur. The aim of this work is to investigate the void formation and evolution processes in order to improve the thermoset laminates quality in minimizing the void ratio. Two phenomena causing void formation have been identified. The first is the mechanical entrapment of gas bubbles between prepreg plies during the lay up. Second is a thermodynamical one. Solvents and humidity absorbed by the prepreg during its manufacturing can be evaporated by increasing the temperature. Then, it has been shown that the vaccum bag lay up permeability in combination with the vaccum pressure could favour the gas washing out. In parallel, thermo-mechanical and diffusion models are coupled to obtain an accurate void size prediction along temperature and pressure applied during the polymerisation. In fact, these two parameters induce variations of the gas bubble radius inside resin. The first experimental results seem to validate qualitatively the calculated void size behaviour. Indeed, hydrostatic pressure imposed during polymerization plays a very important role on gas bubble shrinkage. Finally, a new experimental setup using image analyses has been developed to measure as accurate as possible the volume void ratio. Under specific conditions, stereology allows to extrapolate 2D results to 3D ones. Void ratios obtained with this method are in good agreement with acid digestion results. Complementary morphometric studies on void shapes have given new information about the heterogeneous void distribution in the specimen and also on the statistical void size distribution versus polymerization conditions.

Content: The intrinsic structure significantly influences the mechanical properties of leather. In consequence, knowledge of leather’s hierarchical structure is essential in order to find the most suited leather for specific application. Leather structure based parameters are of major importance for both manufacturing and leather processing industries. In this respect, intensive structure investigations have been subjected in continuous research work. Quantitative image analysis combined with stochastic micro-structure modelling and numerical simulation of macroscopic properties is a promising approach to gain a deeper understanding of complex relations between material’s micro-structure geometry and macroscopic properties. Key ingredient is a reliable geometric description provided by the quantitative analysis of 3D images of the material micro-structures. For leather, both imaging and image analysis are particularly challenging, due to the multi-scale nature of the leather’s micro-structure. Scales in leather are not well separated. Previously, high resolution computed tomography allowed 3D imaging of purely vegetable tanned leather samples at micro- and submicro- scale. Segmentation of leather structure as well as of typical structural elements in resulting image data is however hampered by a strong heterogeneity caused by lower scale structural information. The first method for automatic segmentation of typical structural elements at varying scales combined morphological smoothing with defining and iteratively coarsening regions using the waterfall algorithm on local orientations. It yields a hierarchical segmentation of the leather into coarse and fine structural elements that can be used to analyze and compare the structure of leather samples. Size and shape of the structural elements as well as their sub-structure yield information, e. g. on undulation, branching, thickness, cross-sectional shape, and preferred directions. In order to compare the micro-structure of leather samples from various body parts or even species, the segmentation has to be applicable without extensive pre-processing and parameter tuning. Robustness can be gained by applying smoothing methods that are adapted to the goal of defining image regions by similar local orientation. The challenge is that the space of fiber orientations in 3D is not equipped with an order. Motivated by a recent approach for nevertheless defining erosion and dilation on the sphere, we suggest new definitions for these morphological base transformations on the space of directions in 3D. We present segmentation results for 3D images of leather samples derived by these new morphological smoothing methods. Take-Away: The intrinsic structure significantly influences the mechanical properties of leather. Leather’s hierarchical structure can be analyzed by quantitative 3D image analysis combined with stochastic micro-structure modelling. Segmentation results for 3D images of leather samples derived by new morphological smoothing methods.

During operational conditions of internal combustion turbines of turbojet engines, the impeller are stressed by load cycles which vary in time, temperature and stress. In the course of operation, the blades are exposed to a considerable number of degradation effects, particularly high-temperature corrosion, fatigue processes and creep. The presented work is aimed at the study of the structure cast nickel-base superalloy INCONEL 713 LC, creep tests exposured. The structural changes (degradation) was clasification by the help of image analyses. Operational conditions of heat parts, used in gas turbines and turbo-compressors, were simulated by creep tests of Inconel 713 LC nickel superalloy during a constant load of temperatures ranging from 750 up to 950°C. Changes in the structure dependent upon time, temperature and stress applied were analysed by means of light and electron microscopy methods and image analyses after the fracture of test bars.

During operational conditions of internal combustion turbines of turbojet engines, the impeller blades are stressed by load cycles which vary in time, temperature and stress. In the course of operation, the blades are exposed to a considerable number of degradation effects, particularly high-temperature corrosion, fatigue processes and creep. The presented work is aimed at the study of the structure cast nickel-base superalloy INCONEL 713 LC, creep tests exposured. The structural changes (degradation) was clasifikation by the help of image analyses. Operational conditions of heat parts, used in gas turbines and turbo-compressors, were simulated by creep tests of Inconel 713 LC nickel superalloy during a constant load of temperatures ranging from 750 up to 950C. Changes in the structure dependent upon time, temperature and stress applied were analysed by means of light and electron microscopy methods and image analyses after the fracture of test bars.

A textura e o conteúdo do carbono orgânico (CO) influenciam na resposta espectral dos solos. O estudo desses atributos é de grande importância para a preservação e o manejo adequado da terra na busca de uma agricultura sustentável. O uso de sensores de laboratório e satélites tem se mostrado como uma ferramenta no auxílio para o estudo destes, porém a análise dos atributos do solo com esses sensores tem focado principalmente nas regiões do espectro eletromagnético do visível (Vis), infravermelho próximo (NIR) e infravermelho de ondas curtas (SWIR), com poucos estudos no infravermelho médio (MIR). O objetivo deste trabalho foi identificar o padrão espectral do solo com diferentes granulometrias (areia e argila) e teores de CO utilizando sensores de laboratório e satélite na região do MIR, especificamente na faixa do infravermelho termal (TIR). O estudo teve uma avaliação qualitativa e quantitativa da argila, CO e das frações de areia (fina e grossa). A área de estudo está localizada na região de Piracicaba, São Paulo, Brasil. Foram coletadas 150 amostras de solo a uma profundidade de 0-20 cm. A textura do solo foi determinada pelo método da pipeta e a porcentagem de CO via combustão seca. Dados espectrais em refletância e emissividade (&epsilon;) foram adquiridos com o sensor Fourier Transform Infrared (FT-IR) Alpha (Bruker optics Corporation). Uma imagem \"ASTER_05\" foi adquirida em 15 de julho de 2017 em valores de &epsilon;. As amostras foram separadas por classes texturais e o comportamento espectral no TIR foi descrito. Os dados obtidos pelo sensor de laboratório foram reamostrados para as bandas do sensor de satélite. O comportamento entre os espectros de ambos sensores foi semelhante e teve correlação significativa com os atributos estudados, principalmente para areia. Para os modelos de regressão por mínimos quadrados parciais (PLSR), foram utilizadas seis estratégias (MIR, MIR_ASTER, ASTER, Termal, Termal IDC e MIR IDC) que consistiram no uso de todas as bandas de sensores, ou pela seleção das mesmas que apresentaram as correlações mais significativas com cada um dos atributos. Os modelos apresentaram um bom desempenho na predição de todos os atributos usando o MIR inteiro. No TIR, o modelo para areia total e para as frações fina e grossa foi bom. No caso dos modelos criados com os dados do sensor ASTER, não foram tão promissores quanto os de laboratório. O uso de bandas específicas ajudou a estimar alguns atributos no MIR e no TIR, aumentando o desempenho preditivo melhorando a validação dos modelos. Portanto, a discriminação dos atributos do solo com sensores de satélite pode ser melhorada com a identificação de bandas específicas, como observado nos resultados com sensores de laboratório. / Soil texture and organic carbon (OC) content influence its spectral response. The study of these attributes is relevant for the preservation and proper management of land in pursuit of a sustainable agriculture. Laboratory and satellite sensors have been applied as a useful tool for studying soil attributes, but their analysis with these sensors has mainly focused on the visible (Vis), near infrared (NIR) and shortwave infrared (SWIR) regions of the electromagnetic spectrum, with few studies in the Medium Infrared (MIR). The objective of this study was to identify the spectral pattern of soils with different granulometry (sand and clay) and OC content using laboratory and satellite sensors in the MIR region, specifically in the Thermal Infrared (TIR) range. This study had qualitative and quantitative analyses of clay, OC and sand fractions (fine and coarse). The study area is located in the region of Piracicaba, São Paulo, Brazil. 150 soil samples were collected at a depth of 0-20 cm. Soil texture was determined by the pipette method and the percentage of OC via dry combustion. Reflectance and emissivity (&epsilon;) spectral data were obtained with the Fourier Transform Infrared (FT-IR) Alpha sensor (Bruker Optics Corporation). An image \"ASTER_05\" from July 15, 2017 was acquired with values of &epsilon;. Samples were separated by textural classes and the spectral behavior in the TIR region was described. The data obtained by the laboratory sensor were resampled to the satellite sensor bands. The behavior between spectra of both sensors was similar and had significant correlation with the studied attributes, mainly sand. For the partial least squares regression (PLSR) models, six strategies were used (MIR, MIR_ASTER, ASTER, Thermal, Thermal IDC and MIR IDC), which consisted in the use of all sensors bands, or by the selection of bands that presented the most significant correlations with each one of the attributes. Models presented a good performance in the prediction of all attributes using the whole MIR. In the TIR, models for total sand content and for fine and coarse fractions were good. In the case of models created with ASTER sensor data, they were not as promising as those with laboratory data. The use of specific bands was useful in estimating some attributes in the MIR and TIR, improving the predictive performance and validation of models. Therefore, the discrimination of soil attributes with satellite sensors can be improved with the identification of specific bands, as observed in the results with laboratory sensors.

O desempenho de uma unidade de flotação por ar dissolvido (FAD) em escala piloto, tratando água destinada ao abastecimento contendo 50 uC e 05 uT, foi investigada sob o ponto de vista das partículas presentes (micro-bolhas e flocos) e da hidrodinâmica. A análise centrou-se na zona de reação da unidade de FAD onde foi desenvolvido o modelo matemático proposto por Reali (1991). A determinação das partículas foi realizada por método que emprega a análise de imagem. A condição hidrodinâmica foi avaliada por meio de ensaios de estímulo e resposta, combinada com a análise tridimensional do escoamento feita através de mapeamento utilizando equipamento que emprega ultra-som (sonda micro-ADV). Para a consecução do trabalho foram desenvolvidos dois métodos. Um para aquisição, tratamento e obtenção da distribuição de tamanho de micro-bolhas e flocos utilizando a análise de imagem digital em instalação com escoamento contínuo, sem a extração de amostras. Outro, envolvendo o desenvolvimento de programa (VelDigital3D) para tratamento dos dados da sonda utilizada. Inicialmente, foram realizados os ensaios de validação da utilização da sonda micro-ADV em água contendo micro-bolhas de ar e os ensaios de mapeamento da unidade utilizando a referida sonda conjugada ao programa VelDigital3D. Posteriormente, foram investigados alguns possíveis agentes na aglutinação das micro-bolhas após a despressurização tais como: i) as condições de mistura expressas em termos da taxa de aplicação superficial (TAS) e tempo de detenção na zona de reação (Tdz.r), ii) razão de recirculação (p), iii) a variação de pH e, iv) a dosagem de coagulante (\'AL POT.+3\'). Finalmente, a sensibilidade do modelo matemático proposto por Reali (1991) para a zona de reação de unidades de FAD convencional foi verificada com base nos parâmetros de projeto: tempo de detenção da zona de reação (Tdz.r) e taxa de aplicação superficial na zona de clarificação TASap. (downflow); e com base nos parâmetros operacionais: distribuição de tamanho de partículas (micro-bolhas e flocos) e razão de recirculação (p). As principais conclusões foram: i) a sonda micro-ADV pode ser utilizada para obtenção do perfil de velocidade em águas contendo micro-bolhas de ar, nas vazões investigadas; ii) o escoamento no interior da zona de reação apresentou um padrão bem definido de recirculação ao longo da altura, confirmando os resultados obtidos com os ensaios estímulo e resposta; iii) a variação do diâmetro médio das micro-bolhas foi muito pequena (de 20 a 30 \'mü\'m), embora tenha havido ressalvas e iv) o modelo proposto por Reali (1991) foi sensível aos parâmetros investigados e responde coerentemente com o desempenho da unidade piloto de FAD. / This work investigated the performance of a dissolved air flotation (DAF) pilot plant, used to treat drinking water containing 05 Tu and 50 Cu. The particles (micro-bubbles and flocs) and hydraulic characteristics were taken into account. The focus was given in the reaction zone as hypothesized by Reali\'s mathematic model (REALI, 1991). An image analyses was used to assess particles distribution sizes. The hydraulics of the DAF tank was assessed by using a pulse stimulus-response test combined with the three-dimensional flow analyses carried-out with equipment that applied ultra sound (microADV). Therefore, two methods were developed; one for the acquisition, treatment and also to obtain the micro-bubbles and flocs sizes distribution, without the need of extracting samples and another, involved the development of a software (VelDigital3D) in order to treat the microADV data. Initially, the application of the microADV in the DAF process was evaluated. After, the data collection was made and the result was treated by using the VelDigital3D software. Sequentially, the effects of some agents for micro-bubbles coalescence after the releasing point were investigated: i) mixture conditions in terms of hydraulic loading rate (HLR) and detention time (DT); ii) recirculation rate (p); iii) pH variation and, iv) coagulant dosage (\'AL POT.+3\'). Finally, the mathematic model behavior proposed by Reali (1991) was investigated by varying some parameters in the design, such as: detention time in the reaction zone (DTr.z) and hydraulic loading rate in the clarification zone HLRc.z (dowflow); and by varying some operational parameters, such as: particles sizes distribution (micro-bubbles and flocs) and recirculation rate (p). The main conclusions were: i) the microADV probe can be used to obtain the velocity flow profile in water containing micro-bubbles; ii) the flow within the reaction zone showed a well defined pattern of recirculation throughout the height of the unit, confirming the obtained results by using the stimulus-response tests; iii) the variation of micro-bubbles medium size was low (from 20 to 30 \'mü\'m) but some points regarding this aspect were discussed and, iv) the behavior of the mathematical model proposed by Reali (1991) showed a significant adjustment to the experimental data proving that it can be applied to analyzed design parameters.

O desempenho de uma unidade de flotação por ar dissolvido (FAD) em escala piloto, tratando água destinada ao abastecimento contendo 50 uC e 05 uT, foi investigada sob o ponto de vista das partículas presentes (micro-bolhas e flocos) e da hidrodinâmica. A análise centrou-se na zona de reação da unidade de FAD onde foi desenvolvido o modelo matemático proposto por Reali (1991). A determinação das partículas foi realizada por método que emprega a análise de imagem. A condição hidrodinâmica foi avaliada por meio de ensaios de estímulo e resposta, combinada com a análise tridimensional do escoamento feita através de mapeamento utilizando equipamento que emprega ultra-som (sonda micro-ADV). Para a consecução do trabalho foram desenvolvidos dois métodos. Um para aquisição, tratamento e obtenção da distribuição de tamanho de micro-bolhas e flocos utilizando a análise de imagem digital em instalação com escoamento contínuo, sem a extração de amostras. Outro, envolvendo o desenvolvimento de programa (VelDigital3D) para tratamento dos dados da sonda utilizada. Inicialmente, foram realizados os ensaios de validação da utilização da sonda micro-ADV em água contendo micro-bolhas de ar e os ensaios de mapeamento da unidade utilizando a referida sonda conjugada ao programa VelDigital3D. Posteriormente, foram investigados alguns possíveis agentes na aglutinação das micro-bolhas após a despressurização tais como: i) as condições de mistura expressas em termos da taxa de aplicação superficial (TAS) e tempo de detenção na zona de reação (Tdz.r), ii) razão de recirculação (p), iii) a variação de pH e, iv) a dosagem de coagulante (\'AL POT.+3\'). Finalmente, a sensibilidade do modelo matemático proposto por Reali (1991) para a zona de reação de unidades de FAD convencional foi verificada com base nos parâmetros de projeto: tempo de detenção da zona de reação (Tdz.r) e taxa de aplicação superficial na zona de clarificação TASap. (downflow); e com base nos parâmetros operacionais: distribuição de tamanho de partículas (micro-bolhas e flocos) e razão de recirculação (p). As principais conclusões foram: i) a sonda micro-ADV pode ser utilizada para obtenção do perfil de velocidade em águas contendo micro-bolhas de ar, nas vazões investigadas; ii) o escoamento no interior da zona de reação apresentou um padrão bem definido de recirculação ao longo da altura, confirmando os resultados obtidos com os ensaios estímulo e resposta; iii) a variação do diâmetro médio das micro-bolhas foi muito pequena (de 20 a 30 \'mü\'m), embora tenha havido ressalvas e iv) o modelo proposto por Reali (1991) foi sensível aos parâmetros investigados e responde coerentemente com o desempenho da unidade piloto de FAD. / This work investigated the performance of a dissolved air flotation (DAF) pilot plant, used to treat drinking water containing 05 Tu and 50 Cu. The particles (micro-bubbles and flocs) and hydraulic characteristics were taken into account. The focus was given in the reaction zone as hypothesized by Reali\'s mathematic model (REALI, 1991). An image analyses was used to assess particles distribution sizes. The hydraulics of the DAF tank was assessed by using a pulse stimulus-response test combined with the three-dimensional flow analyses carried-out with equipment that applied ultra sound (microADV). Therefore, two methods were developed; one for the acquisition, treatment and also to obtain the micro-bubbles and flocs sizes distribution, without the need of extracting samples and another, involved the development of a software (VelDigital3D) in order to treat the microADV data. Initially, the application of the microADV in the DAF process was evaluated. After, the data collection was made and the result was treated by using the VelDigital3D software. Sequentially, the effects of some agents for micro-bubbles coalescence after the releasing point were investigated: i) mixture conditions in terms of hydraulic loading rate (HLR) and detention time (DT); ii) recirculation rate (p); iii) pH variation and, iv) coagulant dosage (\'AL POT.+3\'). Finally, the mathematic model behavior proposed by Reali (1991) was investigated by varying some parameters in the design, such as: detention time in the reaction zone (DTr.z) and hydraulic loading rate in the clarification zone HLRc.z (dowflow); and by varying some operational parameters, such as: particles sizes distribution (micro-bubbles and flocs) and recirculation rate (p). The main conclusions were: i) the microADV probe can be used to obtain the velocity flow profile in water containing micro-bubbles; ii) the flow within the reaction zone showed a well defined pattern of recirculation throughout the height of the unit, confirming the obtained results by using the stimulus-response tests; iii) the variation of micro-bubbles medium size was low (from 20 to 30 \'mü\'m) but some points regarding this aspect were discussed and, iv) the behavior of the mathematical model proposed by Reali (1991) showed a significant adjustment to the experimental data proving that it can be applied to analyzed design parameters.