Thesis (MScAgric)--Stellenbosch University, 2011. / ENGLISH ABSTRACT: Shiraz/110R grapevines, growing in a fine sandy loam soil in the Breede River Valley, were subjected to ten different drip irrigation strategies during the 2006/07, 2007/08 and 2008/09 seasons. Grapevines of the control treatment (T1) were irrigated at 30% to 40% plant available water (PAW) depletion throughout the growing season. Grapevines of three treatments were irrigated at 70% to 80% PAW depletion from bud break until véraison (i.e. when ca. 95% of grape berries have changed colour), followed by either irrigation at 30% to 40% PAW depletion (T2) or a continuous deficit irrigation (CDI) strategy (T3) or irrigation at 70% to 80% PAW depletion (T4) during ripening. The CDI strategy was obtained by applying ca. half the volume of water that was applied to the control. This allowed the soil to dry out gradually between physiological stages (i.e. bud break and véraison or véraison and harvest). Grapevines of three further treatments were irrigated at ca. 90% PAW depletion from bud break until véraison, followed by irrigation at 30% to 40% PAW depletion (T5) or a CDI strategy (T6) or irrigation at ca. 90% PAW depletion (T7) during ripening. Grapevines of two treatments were irrigated by means of a CDI strategy from bud break until véraison. For both treatments, the soil water content (SWC) was allowed to dry out gradually until ca. 90% PAW depletion was reached. After véraison, the SWC of the one treatment was maintained at ca. 90% PAW depletion by applying only four small irrigations of three hours each during ripening (T8). The soil of the other treatment, received an irrigation at véraison to refill the SWC to field capacity (T9) followed by the CDI strategy during ripening. Grapevines of the tenth treatment were irrigated at ca. 90% PAW depletion between bud break and véraison followed by a partial profile refill (PPR) strategy during ripening (T10). In order to obtain the PPR strategy, SWC was only maintained between 40% and 60% PAW depletion. Evapotranspiration varied between 3.5 mm/day and 0.1 mm/day for driest and wettest treatments, respectively, during the period between December and February. This was substantially less than the volumes required for full surface irrigation. For irrigations applied at 30% to 40% PAW depletion (T1), 70% to 80% PAW depletion (T4) and ca. 90% PAW depletion (T7) levels throughout the season, crop coefficients for the Penman-Monteith reference evapotranspiration (ETo) were 0.4, 0.2 and 0.1, respectively. Under the given conditions, the different irrigation strategies did not have any effect on root distribution and density. Shoot growth of grapevines exposed to high to severe water deficits in the pre-véraison period stopped before mid December. Shoots of grapevines that were exposed to high or severe water deficits before véraison followed by more frequent irrigation during ripening showed active re-growth. These trends occurred during all the seasons. The level of PAW depletion reflected strongly in the plant water potential in the grapevines. Leaf water potential was influenced by the prevailing atmospheric conditions, whereas stem water potential was less sensitive to atmospheric conditions, but responded more directly to soil water availability. Due to the good relationships between pre-dawn leaf, mid-day leaf, mid-day stem and total diurnal water potential, it was possible to re-classify the water status in terms of previous classifications for these water potentials based on pre-dawn measurements. Water constraints in T1, T2 and T5 grapevines were classed as experiencing no stress, whereas the T7 and T8 ones experienced strong to severe water constraints before harvest. High frequency irrigation strategies during ripening delayed sugar accumulation due to dilution of sugar in the larger berries. Except for the wettest strategy, and where grapevines were subjected to the CDI strategy throughout the season, berry mass increased during ripening, i.e. from véraison to harvest. Water deficits had a negative effect on berry mass, bunch size and yield. Where higher soil water depletion levels were allowed, irrigation strategies had a positive effect on the irrigation water productivity of grapevines compared to the frequently irrigated or CDI strategies. Higher water constraints in grapevines, particularly during ripening, improved sensorial wine colour and enhanced some of the more prominent wine aromas, e.g. spicy and berry. Grapevines that were irrigated at a high frequency during ripening produced wines with diluted character flavours and aromas and inferior overall quality. Under the given conditions, sensorial wine colour and spicy character were the dominant factors in determining overall sensorial wine quality. / AFRIKAANSE OPSOMMING: Shiraz/110R wingerdstokke in ‘n fyn sandleem grond in die Breede Rivier vallei is gedurende die 2006/07, 2007/08 en 2008/09 seisoene met tien verskillende drupbesproeiingstrategieë besproei. Wingerdstokke van die kontrole (B1) is deur die seisoen by 30% to 40% plant beskikbare water (PBW) onttrekking besproei. Drie behandelings is tussen bot en deurslaan (wanneer ca. 95% van die korrels verkleur het) by 70% tot 80% PBW onttrekking besproei, gevolg deur besproeiing by 30% tot 40% PBW onttrekking (B2), ‘n deurlopende tekort besproeiing (DTB) strategie (B3) of besproeiing by 70% tot 80% PBW onttrekking (B4) gedurende rypwording. In die geval van die DTB strategie is ongeveer die helfte van die volume water toegedien wat by die kontrole toegedien is. Laasgenoemde strategie het die grond toegelaat om geleidelik tussen fisiologiese fases (i.e. tussen bot en deurslaan of tussen deurslaan en oes) uit te droog. Drie ander behandelings is by ca. 90% PBW onttrekking tussen bot en deurslaan besproei, gevolg deur besproeiing by 30% tot 40% PBW onttrekking (B5) of ‘n DTB strategie (B6) of besproeiing by ca. 90% PBW onttrekking (B7) gedurende rypwording. Wingerdstokke van twee ander behandelings is d.m.v. ‘n DTB strategie vanaf bot tot deurslaan besproei. Beide behandelings se grondwaterinhoud (GWI) was toegelaat om geleidelik uit te droog tot ca. 90% PBW onttrekking bereik was. Na deurslaan was die GWI van die een behandeling naby ca. 90% PBW onttrekking gehandhaaf deur slegs vier klein besproeiings van drie uur elk gedurende rypwording toe te pas (B8). Die grond van die ander behandeling het tydens deurslaan ‘n besproeiing ontvang om die GWI tot by veldkapasiteit te hervul (B9) en is tydens rypwording weer d.m.v. ‘n DTB strategie besproei. Stokke van die tiende behandeling is tussen bot en deurslaan by ca. 90% PBW onttrekking besproei, gevolg deur besproeiing d.m.v. ‘n gedeeltelike profiel hervul (GPH) strategie tydens rypwording (B10). Om ‘n GPH strategie toe te kon pas, is tussen 40% en 60% PBW ontrekking gehandhaaf. Evapotranspirasie het tussen 3.5 mm/dag en 0.1 mm/dag vir onderskeidelik die natste en droogste behandelings tussen Desember en Februarie gevarieer. Dit was aansienlik laer as volumes wat vir voloppervlak besproeide wingerde benodig word. In die geval van besproeiing by 30% tot 40% PBW onttrekking (B1), 70% tot 80% PBW onttrekking (B4) en ca. 90% PBW onttrekking (B7) deur die loop van die seisoen was die gewasfaktore vir die verwysingverdamping (ETo) 0.4, 0.2 en 0.1 onderskeidelik. Onder die gegewe toestande het die verskillende besproeiingstrategië geen effek op die worteldigtheid en –verspreiding gehad nie. Lootgroei van wingerdstokke wat aan hoë tot baie hoë watertekorte blootgestel was voor deurslaan, het voor middel Desember gestop. Lote van wingerdstokke wat aan hoë tot baie hoë watertekorte voor deurslaan blootgestel is, gevolg deur besproeiing teen ’n hoë frekwensie tydens rypwording, het aktiewe hergroei getoon. Die PBW ontrekkingspeil het sterk in die plantwaterpotensiale van wingerdstokke weerspieël. Blaarwaterpotensiaal is deur heersende klimaatstoestande beïnvloed, terwyl stamwaterpotensiaal minder sensitief teenoor die klimaat was, maar meer direk deur die beskikbaarheid van grondwater beïnvloed is. Vanweë die goeie verband tussen voordagbreek blaar-, mid-dag blaar-, mid-dag stam- en totale daaglikse waterpotensiaal, was dit moontlik om water status van die stokke te her-klassifiseer in terme van vorige vir waterpotensiaalklassifikasies wat op voordagbreek waardes gebasseer is. Waterspanning in B1, B2 en B5 stokke is as geen spanning geklassifiseer, terwyl dié van B7 en B8 voor oes in die hoë tot baie hoë klasse geval het. Hoë frekwensie besproeiing strategieë gedurende rypwording kan suikertoename a.g.v. die groter korrels vertraag. Met die uitsondering van die natste strategie, asook waar stokke volgens die DTB strategie deur die seisoen besproei is, het korrelmassa gedurende rypwording toegeneem. Watertekorte het ’n negatiewe effek op korrelmassa, trosgrootte en produksie gehad. Besproeiingstrategieë waar ’n hoë mate van grondwateronttrekking voor besproeiings toegelaat is, het ’n positiewe effek op die besproeiingwaterproduktiwiteit van wingerd in vergelyking met gereelde besproeiings of ‘n DTB strategie gehad. Watertekorte, veral gedurende rypwording, het ’n verbetering in sensoriese wynkleur en meer prominente wyn aromas, tot gevolg gehad. Besproeiing teen hoë frekwensies gedurende rypwording, het wyne met ’n afgewaterde smaak en aroma karakters asook ’n swak algehele gehalte produseer. Sensoriese wynkleur en spesery karakter die dominante faktore in die bepaling van algehele kwaliteit.

No description available.

La mobilisation des REE et de l’Hf par un fluide aqueux durant les processus métamorphiques HP-BT peut entraîner des perturbations dans la signature des protolithes et/ou dans les datations obtenues par les systèmes isotopiques Sm-Nd et Lu-Hf. L’étude couplée de la transition éclogite - amphibolite de la localité de Vårdalsneset (WGR, Norvège) et des coefficients de partage des REE et de l’Hf entre un fluide aqueux à NaCl ou à CO2 et le grenat pyrope (P = 3 GPa, T = 800°C) déterminés expérimentalement conduit à deux résultats majeurs. Tout d’abord, une différence d’échelle de mobilité entre les REE (mobiles à l’échelle décimétrique) et l’Hf (mobile à l’échelle du grain) est démontrée. Les signatures des protolithes restent cependant identifiables et les âges modèles Sm-Nd et Lu-Hf des métabasites ne sont pas perturbés, arguant d’une mobilité restreinte des REE. Ensuite; cette étude montre l’influence du CO2 dissous dans le fluide aqueux sur le partage fluide-roche des HREE. L'étude expérimentale indique que les HREE sont incompatibles dans le pyrope en présence d'un fluide à CO2. Ces résultats permettent d’expliquer l’appauvrissement en HREE sous l'effet de fluides à H2O-CO2 ou à CO2 des métabasites de Vårdalsneset. / REE and Hf mobility in aqueous fluids during HP-BT metamorphism can disturb magmatic signatures of protoliths and Sm-Nd and Lu-Hf dating. This study performed on both natural samples from Vårdalsneset (WGR, Norway) and experimental estimates of REE and Hf partition coefficients between aqueous fluid with NaCl or CO2 and pyrope (P = 3 GPa, T = 800°C) highlights two main results. Firstly, REE can be mobilized at the sample scale (tens of centimetres) whereas Hf is only mobilized at the grain scale. Magmatic signatures of protoliths are nevertheless recognizable and Nd and Hf model ages are not disturbed, that suggests slight mobility of REE. Secondly, an aqueous fluid with CO2 induces an incompatible behaviour of HREE in pyrope, which can explain the depletion in HREE of the metabasites of Vårdalsneset in presence of a H2O-CO2 or CO2 fluid.

Title: Models of integer-valued time series with random coefficients Author: Petra Burdejová Department: Department of Probability and Mathematical Statistics Supervisor: Doc. RNDr. Zuzana Prášková, CSc. Abstract: In the presented thesis, a generalized integer-valued autoregres- sive process of the order p (GINAR(p)) is considered first. The main aim is taken to introduction of random coefficient integer-valued autoregressive process (RCINAR(p)). We use a thinning operator in order to define the processes. The main characteristics of GINAR(p) and RCINAR(p) are obtained. Condi- tions for stationarity and ergodicity are stated. Three methods of estimation (Yule-Walker, Conditional least squares, Generalized method of moments) are given and compared in simulation with respect to the mean squared error (MSE). At the end, RCINAR(3) model is applied to a real dataset representing a number of earthquakes per year. Keywords: thinning operator, random coefficients, integer-valued time se- ries, GINAR, RCINAR

Le radical nitrate NO₃ est un intermédiaire clé dans la chimie atmosphérique nocturne. Il peut réagir avec un certain nombre de composés organiques volatils (COV) initiant leur dégradation pendant la nuit. Dans cette thèse, la cinétique de NO₃ avec plusieurs de ces composés a été étudiée à température ambiante (298 ± 2K) et à pression atmosphérique (1000 ± 5 hpa) dans une chambre de simulation atmosphérique en Téflon(ICARE-7300L) couplée à des outils analytiques tels que : FTIR, PTR-ToF-MS and CRDS etc. Nous avons déterminé les constantes de vitesse pour les réactions du radical NO3 avec sept esters de méthacrylate à température ambiante: méthacrylate de méthyle, méthacrylate d'éthyle, méthacrylate de propyle,méthacrylate d'isopropyle, méthacrylate de butyle, méthacrylate d'isobutyle, méthacrylate de méthyle deutéré. Les résultats obtenus, suggèrent que la réaction de NO₃ avec les esters de méthacrylate procède par addition sur la double liaison du groupe méthacrylate. Ensuite, une méthode absolue a été utilisée pour déterminer les constantes de vitesse de réaction de NO₃ avec une série d'alcanes et de gaz inorganiques importants dans les processus atmosphériques : le méthane, l'éthane, le pentane, le n-butane, l’isobutane, le2, 3-diméthylbutane, le cyclopentane, le cyclohexane, l'oxyde nitreux, le monoxyde de carbone et le dioxyde de soufre. Avec l’ensemble des données cinétiques obtenues, les durées de vie atmosphériques de ces composés vis à vis des radicaux NO₃ ont été calculées et comparées à celles déterminées pour d’autres oxydants de l’atmosphère. Ces résultats améliorent également les connaissances de base sur les réactions impliquant le radical NO₃. / NO₃ is a key intermediate in the chemistry of the night-time atmosphere. NO₃ radical can react with anumber of VOCs initiating their night-time degradation. In this thesis, the kinetics of NO₃ with different kinds of compounds was studied at room temperature (298 ± 2 K) and atmospheric pressure (1000 ± 5 hpa) in a Teflon simulation atmospheric chamber (ICARE-7300L) coupled to analytical tools including Fourier Transform Infrared Spectroscopy, Proton Transfer Reaction-Time of Flight-Mass Spectrometer and CavityRing Down Spectrometer etc. The rate coefficients for the reactions of NO₃ radical with seven methacrylate esters are firstly reported: methyl methacrylate; ethyl methacrylate; propyl methacrylate; isopropylmethacrylate, butyl methacrylate, isobutyl methacrylate, and deuterated methyl methacrylate. The trends in the measured rate coefficient with the length and nature of the alkyl group strongly suggest that the reaction proceeds via addition to the double bond on the methacrylate group. Then, an absolute method was used to determine the upper limits or rate coefficients for the reactions of NO₃ radicals with a series of alkanes and some important inorganic gases: methane, ethane, pentane, n-butane, iso-butane, 2,3-dimethybutane,cyclopentane, cyclohexane, nitrous oxide, carbon monoxide and and sulfur dioxide. With the obtained kinetics data, the atmospheric lifetimes of these compounds toward NO₃ radicals were calculated and compared with those due to loss via reactions with the other major atmospheric oxidants. The kinetics results also enhance the available database on NO₃ reactions.

Un fondu de polymères est un liquide complexe constitué de chaînes macromoléculaires. Ces chaînes présentent la particularité d'offrir une distribution de temps caractéristiques extrêmement importante. L'ensemble de ces différentes échelles représente donc un défi pour la simulation numérique de polymères longs et sont bien au-delà des capacités des ordinateurs actuels. Un thème actuel de recherche porte donc sur le développement de modèles mésoscopiques (modèle gros grains). La construction d'un tel modèle consiste à éliminer les degrés de liberté rapide en regroupant un certain nombre d'atomes en un monomère. Ce monomère est représenté par une sphère molle évoluant dans un bain thermique créé par les degrés de liberté rapides éliminés au cours du processus de nivellement. La dynamique des particules créées est donc stochastique. La dynamique particulaire dissipative qui intègre ces idées est une combinaison de dynamique moléculaire, de Lattice Gas Automata ainsi que de dynamique Brownienne. Le champ de force DPD est constitué d'une interaction molle et d'un thermostat (force dissipative et bruit) et les paramètres de ce champ de force sont généralement calibrés sur des données expérimentales (compressibilité et diffusion). Cette approche est difficilement applicable aux mélanges de polymères. Pour surmonter cette difficulté, l'intégralité du champ de force DPD est construit à partir d'une dynamique moléculaire pour des corps purs ainsi que pour des mélanges. Nous montrons également que pour calculer correctement la force dissipative, la dynamique moléculaire doit être altérée en contraignant la position des monomères. Les coefficients de transport sont calculés par DPD et comparés à ceux obtenus par dynamique moléculaire. Ce travail s'achève par une étude de la transferabilité du champ de force du monomère vers toute une chaîne de polymères. / A molten polymer is a complex liquid consisting of macromolecular chains. These chains have many different time scales. All these scales present a real challenge to numerical simulations and exceed the computational capabilities of today's computers. A current topic of research therefore focuses on the development of mesoscopic models. The main idea behind coarse-graining is to eliminate fast degrees of freedom grouping atoms or molecules into clusters (or monomers). This monomer is represented by a soft sphere operating in a thermal bath generated by the fast degrees of freedom eliminated during the coarse-graining. Particle dynamics is therfore stochastic. Dissipative particle dyna-mics, which includes these ideas, is a combination of molecular dynamics, Lattice Gas Automata and Brownian dynamics. DPD force field consist of a soft interaction and a thermostat (dissipative and random force) and parameters of DPD interaction are generally optimized to match some macroscopic properties like compressibility or self-diffusion coefficient. This approach is difficult to apply to polymer melt. To overcome this problem, we apply an operational procedure available in the literature to the cons-truction of conservative and dissipative forces of DPD force field for pure substances and mixtures. We also show that in order to calculate the dissipative forces, the underlying molecular dynamics must be altered by constraining the position of the mo-nomers. Transport coefficients are calculated by DPD and compared with those obtained by molecular dynamics. This work concludes with a study of the transferability of the force field of the monomer to a chain of polymers.

A dose glandular média é a grandeza utilizada para dosimetria em mamografia. Esta grandeza apresenta grande dependência com propriedades específicas referentes ao tipo de mama a ser avaliada, tais como sua glandularidade e espessura comprimida. Depende também das propriedades do espectro de raios X, tais como a combinação anodo/filtro e a tensão aplicada ao tubo, que modificam a camada semirredutora do feixe. A caracterização do feixe de raios X através da medição direta do seu espectro é um procedimento de alta complexidade e de difícil execução em sistemas de mamografia, devido à arquitetura dos equipamentos e da alta taxa de fluência de fótons característica dos feixes. Estes espectros representam a fonte de informações quantitativas e qualitativas mais completa do feixe. O objetivo geral desse trabalho é estimar distribuições de dose glandular em diferentes profundidades de materiais simuladores de tecido mamário por meio de espectros de raios X medidos em mamógrafos. Para isso, foram utilizadas técnicas radiográficas comumente empregadas na mamografia para o rastreamento do câncer de mama. Foi avaliado o comportamento da dose glandular média normalizada pelo kerma no ar incidente (DgNp) com parâmetros relacionados à mama (glandularidade e espessura) e aos espectros (camada semirredutora, tensão, combinação alvo/filtro). Primeiramente, foi desenvolvida uma metodologia experimental para medição dos espectros de raios X nos mamógrafos. Em seguida, foram propostos os seguintes métodos de cálculo da DgNp utilizando esses espectros: Método I, que calcula a DgNp com espectros incidentes; Método II, que utiliza espectros incidentes e transmitidos para este cálculo e Método III, que usa espectros incidentes e transmitidos para estimar a distribuição de dose em profundidade. Por fim, para efeito de comparação, a distribuição da DgNp também foi estimada utilizando dosímetros termoluminescentes (TLDs). A metodologia desenvolvida para medição de espectros mostrou-se eficaz para posicionamento e alinhamento adequados do detector no feixe e consequentemente a medição dos espectros diretos. Os espectros incidentes experimentais mostraram boa concordância com espectros simulados. Os resultados mostraram uma distribuição bem-comportada desses coeficientes (DgNp), com tendência linear ou exponencial, com relação aos parâmetros analisados. Para um dado espectro, os valores de DgNp apresentaram decrescimento exponencial com a espessura do material simulador ao tecido mamário e dependencia linear com a glandularidade. Além disso, esses coeficientes crescem linearmente com o aumento da camada semirredutora e, consequentemente, com a energia efetiva. A partir das distribuições de DgNp (obtidas pelo Método III) foi possível estimar a dose no volume completo da mama com diferença máxima de 5,2% dos valores obtidos com o Método II. A variação da DgNp com a profundidade obtidas com TLDs mostrou-se bastante coerente com os resultados observados com a utilização do Método III. Conclui-se que é possível avaliar a dose glandular em mamografia utilizando espectros de raios X e que a metodologia proposta tem potencial para ser aplicada como procedimentos alternativos para dosimetria em mamografia. / The mean glandular dose is the quantity used for dosimetry in mammography. This quantity has a strong dependence with some properties of the evaluated breast, such as its glandularity and compressed thickness. It also depends on the X-ray spectrum used for the mammographic image production, such as the target/filter combination and the tube voltage, which are related to the half value layer (HVL) of the beam. The X-ray beam characterization by means of the direct measurement of its spectrum is a complex procedure, and it is difficult to be implemented in clinical systems due to the architecture of the mammography equipment and the high photon fluence rates. These spectra provide a complete qualitative and quantitative information of the X-ray beam. The general objective of this work is to estimate mean glandular dose distributions in different depths of breast tissue-equivalent materials (bTEM) considering the X-ray spectra measured in clinical mammography devices. Radiographic techniques commonly applied for breast cancer screening were used. The behavior of the mean glandular dose normalized to the incident air kerma (DgNp), with parameters related to the breast (glandularity and compressed thickness) and to the mammographic spectra (HVL, tube voltage, target/filter combination), was evaluated. First, an experimental methodology was developed to measure X-ray spectra in clinical mammography devices. Then, the following methods for calculating the DgNp using these spectra were considered: Method I, which calculates the DgNp using the incident spectra; Method II, which uses incident and transmitted spectra by the bTEMs, and Method III, which uses incident and transmitted spectra to estimate the dose distributions in depth of the breast equivalent materials. Finally, thermoluminescent dosimeters (TLDs) were used as a comparative method to evaluate DgNp distributions. The methodology developed for measuring spectra proved to be efficient for the proper positioning and alignment of the detector and, consequently, for the measurement of direct X-ray spectra. The experimental incident spectra showed good agreement with spectra simulated in similar conditions. The results showed well-defined trends (either linear or exponential) of the distributions of these coefficients (DgNp) regarding the analyzed parameters. The DgNp values presented an exponential decay with the bTEM thickness and linear decrease with the glandularity. In addition, these coefficients increase linearly with the increase of the HVL and, consequently, with the increase of the effective energy. From the distributions of DgNp (obtained by Method III) it was possible to estimate the DgNp in the whole breast with a maximum difference of 5.2% from the values obtained using the Method II. The variation of the DgNp with the depth, obtained with TLDs, showed to be consistent with the results observed using the Method III. In conclusion, it is possible to evaluate the glandular dose in mammography examinations using X-ray spectra and the suggested methodology, with some adaptations, can be applied as an alternative procedure for dosimetry in mammography.

O uso do cloro como desinfetante em sistemas de água para abastecimento é prática comum nas estações de tratamento de água. Introduzido durante o processo de tratamento, o cloro participa de diversas reações com compostos de naturezas orgânicos e inorgânicos no interior das tubulações. Tais reações ocorrem na massa líquida e junto às paredes das tubulações e são responsáveis pelo decaimento do cloro ao longo das redes. Visualizando a modelagem como uma ferramenta eficiente para gerenciar o cloro residual em sistemas de distribuição de água, muitos estudos foram realizados e reportados pela literatura, assumindo que os efeitos de decaimento de cloro podem ser bem representados pelos coeficientes kb e kw. Entretanto, a determinação de valores para parâmetros em questão não é uma tarefa fácil, devido à complexidade dos sistemas enfocados em termos da diversidade de materiais das tubulações e mananciais (superficiais e subterrâneos). No Brasil, apesar de legislação recente estabelecer limites restritivos para o cloro na água potável (após desinfecção, a concentração de cloro deve observar a concentração mínima de 0,5 mg/L, sendo o mínimo nível aceito em sistemas de distribuição de 0,2 mg/L e o máximo de 2,0 mg/L), poucos estudos enfocam a avaliação dos parâmetros de decaimento. Esta pesquisa apresenta a aplicação de um modelo inverso elaborado para determinar a ordem para o modelo de decaimento do cloro e os valores globais e/ou locais para o kb e o kw. Sendo programado com o suporte do simulador de EPANET 2 (toolkit) e os algoritmos genéticos como ferramenta de otimização, implementado através da biblioteca de GAlib C++. Os estudos foram realizados em dois sistemas reais da distribuição da água em que foram considerados parâmetros globais e parâmetros específicos da qualidade. Para a investigação da determinação de parâmetros de decaimento de cloro em sistemas de distribuição com vazamento em função da pressão, foi adotada uma rede hipotética com três fontes de cloro. Esse sistema permitiu a calibração e a validação do modelo, assim como a avaliação da influência hidráulica na determinação dos resultados de qualidade de água. / The use of chlorine as disinfectant in water supply systems has been a common practice adopted by the water industry. Introduced during the treatment process, chlorine participates in several reactions with compounds of organic and inorganic nature inside the pipes. Such reactions that occur in the bulk and the wall of the pipes are responsible for chlorine decay along the networks. Visualizing the modeling as an efficient tool to manage the chlorine residual in water distribution systems, many studies have been conducted and reported by the literature, assuming that the chlorine decay effects can be well represented by the decay coefficients kb and kw. However, the determination of values for theses parameters is not an easy task, due to the complexity of the focused systems in terms of pipe materials and water supply sources diversity (surface water and groundwater). In Brazil, instead of recent legislation stating more strict limits for chlorine in drinking water (after disinfection, chlorine concentration has to observe the minimum concentration of 0.5 mg/L, being the minimum accepted level in the distribution system of 0.2 mg/L and the maximum of 2.0 mg/L), few studies focus on the evaluation of the decay parameters. This research reports the application of an inverse model built to determine the order for chlorine decay model and the global and/or local values for kb and kw. It is codified with the support of EPANET 2 (Toolkit) simulator and technology of genetic algorithms as optimization tool, which is implemented by using the GAlib C++ library. The studies were conducted on two real water distribution systems considering both global and specific quality parameters. A hypothetical network with three sources of chlorine was studied too, admitting leakage as pressure function. This system permitted both calibration and validation of the model as well as the evaluation of hydraulic calibration influence on the water quality results.

In this thesis we use the holographic gauge/gravity duality to study two different aspects of strongly coupled non-Abelian plasmas. In the first topic we study the effects of strong (Abelian) magnetic fields on the transport coefficients of a strongly coupled non-Abelian plasma. Due to the spatial anisotropy created by the magnetic field, the most general viscosity tensor of a magnetized plasma has 5 shear viscosity coefficients and 2 bulk viscosities. We use the holographic correspondence for a strongly coupled N=4 Supersymmetric Yang-Mills (SYM) plasma to evaluate the shear viscosity perpendicular to the magnetic field and the shear viscosity parallel to the field. In the presence of a magnetic field, the shear viscosity perpendicular to the field saturates the Kovtun-Son-Starinets viscosity bound while in the direction parallel to the field the bound is violated. The second topic investigated in this thesis is motivated by the study of the near equilibrium behavior of strongly interacting non-Abelian plasmas that display a critical point in their phase diagram. We focus on the spectra of non-hydrodynamic quasinormal modes of a strongly coupled N=4 SYM plasma in the presence of a chemical potential, which displays a critical point in equilibrium. Except close to the critical point, we observe that by increasing the chemical potential one generally increases the damping rate of the quasinormal modes, which leads to a reduction of the characteristic equilibration times in the dual strongly coupled plasma. However, as one approaches the critical point the typical equilibration time increases though its derivative with respect to the chemical potential diverges with an exponent equal to -1/2. We also find a purely imaginary non-hydrodynamical mode in the vector diffusion channel at nonzero chemical potential which dictates the equilibration time in this channel near the critical point. / Nessa tese usamos a dualidade holográfica calibre/gravidade para estudar dois aspectos diferentes de plasmas não-Abelianos fortemente acoplados. No primeiro tópico estudamos os efeitos de campos magnéticos (Abelianos) intensos sobre o coeficientes de transporte de um plasma não-Abeliano fortemente acoplado. Devido à anisotropia espacial criada pelo campo magnético, o tensor de viscosidade mais geral de um plasma magnetizado deve possuir 5 coeficientes de viscosidade de cisalhamento e 2 de viscosidade volumétrica. Usamos a correspondência holográfica para um plasma N=4 Supersimétrico de Yang-Mills (SYM) fortemente acoplado para calcular a viscosidade de cisalhamento perpendicular ao campo magnético e a viscosidade de cisalhamento paralela ao campo. Na presença do campo magnético, a viscosidade de cisalhamento perpendicular ao campo satura o limite viscoso de Kovtun-Son-Starinets enquanto que na direção paralela ao campo o limite é violado. O segundo tópico investigado nessa tese é motivado pelo estudo do comportamento próximo ao equilíbrio de plasmas não-Abelianos fortemente interagentes que exibem um ponto crítico em seus diagramas de fase. Focamos no espectro dos modos quasinormais não-hidrodinâmicos de um plasma N=4 SYM fortemente acoplado na presença de um potencial químico, que exibe um ponto crítico no equilíbrio. Exceto próximo ao ponto crítico, observamos que ao aumentar o potencial químico geralmente se intensifica a taxa de amortecimento dos modos quasinormais, que levam à redução dos tempos de equilibração característicos do plasma dual fortemente acoplado. Entretanto, aproximando-se do ponto crítico o tempo de equilibração típico aumenta embora sua derivada em relação ao potencial químico diverge com um expoente igual à -1/2. Encontramos também um modo não-hidrodinâmico puramente imaginário no canal de difusão vetorial com potencial químico não-nulo que dita o tempo de equilibração neste canal próximo do ponto crítico.

Desenvolvemos urna teoria cinética para urna mistura de gases ionizados em presença de campos elétricos e magnéticos. As leis de Ohm, Fourier e Navier-Stokes são obtidas por dois métodos distintos que se baseiam na equação de Boltzmann. Verificamos que o emprego de teoremas de representação torna o método de Chapman-Enskog mais direto. Entretanto o método combinado mostrou-se extremamente simples, onde os coeficientes de transporte são determinados através da inversão de tensores de segunda e quarta ordens. Calculamos também a integral de colisão para as possíveis interações em gases ionizados tais como, entre partículas carregadas, partícula carregada e partícula neutra e entre partículas neutras. Como uma aplicação do método combinado, determinamos os coeficientes de condutividade elétrica, condutividade térmica, coeficiente termo-elétrico e o coeficiente de viscosidade cisalhante para um gás totalmente ionizado. Obtemos seus respectivos gráficos, considerando então um gás ionizado formado a partir do gás de hélio. / We develop a kinetic theory for ionized gases mixtures under the presence of electric and magnetic fields. The laws of Ohm, Fourier and Navier-Stokes are obtained by two different methods based on the Boltzmann equation. We verify that the use of representation theorems makes the Chapman-Enskog method more direct. However the combined method shows up as extremely simple where the transport coefficients are determined through inversion of second-order and fourth order tensors. We calculate also the collision integrals for possible interactions in ionized gases like: between charged particles, between charged particles and neutral particles and between neutral particles. As an application of the combined method, we determine the electrical and thermal conductivity coefficients, thermo-electric and shear viscosity coefficients for a completely ionized gas. We obtain their respective graphics considering an ionized gas of helium.