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Swine production represents approximately 40% of the world's meat production, and its wastes contain high concentrations of organic carbon, nitrogen (N), and phosphorus (P). Anaerobic digestion is an increasingly popular technology for treating animal wastes while simultaneously generating energy. Its propagation and ability to solubilize organic N and P make adding a struvite recovery process attractive. Recovering struvite (MgNH4PO4) from anaerobically digested swine waste can address global P shortages, meet P discharge guidelines, and produce slow-release fertilizer, which can be sold for revenue. Anaerobic digesters were operated with at organic loading rates of 3.4-3.9 g volatile solids per liter per day to provide consistent effluent for struvite precipitation studies. Three research questions about struvite precipitation were addressed in this study, specifically what is the (1) required Mg:PO4 ratio, (2) effect of organic matter, and (3) effect of storage time and conditions on struvite precipitation from effluent of anaerobically digested swine manure? Mg:PO4 ratios between 1.3-1.8 were determined to be the economic optimum and precipitated 81-90% of P from synthetic wastewater with calcium phosphate minerals dominating. Under P-limited conditions, a chemical equilibrium model (Visual MINTEQ v.3.0) predicted over 99% P removal with a precipitate mixture of struvite, calcium phosphates, and magnesite. Synthetic wastewater experiments without organic matter removed approximately 85% P with a precipitate mixture of struvite, dolomite, calcite, brucite, and calcium phosphates. Real swine effluent removed more than 95% of P and had a similar mixture of precipitates as synthetic wastewater, but in different concentrations. Organic acids were suspected to prevent struvite formation. Stored anaerobically digested swine wastewater under varying conditions all suggest calcium phosphates form naturally over time. Precipitation of struvite is best carried out as soon as possible to increase the purity of struvite. Although struvite recovery was possible, the conditions for struvite precipitation must be controlled carefully to obtain highly pure struvite.

Coaxial jet flows have a considerable practical application area as water jet pumps. Efficiency of such systems is affected by complex turbulence mechanisms and large-scale vortex structures formed in the mixing regions. An experimental setup is constructed to estimate the momentum exchange rates and mixing of the two jet flows from the coaxial pipes. Pressure distributions along the mixing pipe wall are measured for different flow ratios of the jets. In addition to present experiments, numerical data of two experimental studies from the literature are considered as test cases. Numerical solutions for the test cases are obtained using FLUENT. Experimental and numerical results are compared and adequacy of FLUENT solution is illustrated.

The confined impinging jet reactor gives efficient mixing performance as required for fast reactions. In this work the mixing performance of CIJR is characterized through three measures: estimates of the energy dissipation, micromixing efficiency based on the yield of a homogeneous (iodide-iodate) reaction and particle size resulting from a heterogeneous (iron oxide) precipitation reaction. Whereas product yield and energy dissipation are used to test operational robustness of CIJR, iron oxide model system is used to study the effect of feed flow rate (mixing) and reactant concentration on precipitate agglomerate size. Mixing and concentration effects on nucleation, particle growth and particle agglomeration are tracked to understand the agglomeration process. Various types of stabilizers and additive concentrations to limit particle agglomeration are also tested. Effects of in situ and post-reaction sonication on agglomerate size are also investigated. Efforts are made to determine variations in mixing efficiency the operational robustness of the scale-up (2X and 4X) geometries. Also efforts are made to identify scaling parameters and the limit on geometric scale-up for good mixing performance. Energy dissipation is found to vary between 20 W/kg and 6800 W/kg in CIJR and decreases on scale-up at constant Reynolds number. The operation of the CIJR and the scale-up geometries is robust to changes in flow rate, exhibiting stable performance up to 30% difference in inlet flow rates. Reliable mixing performance is obtained until 2X scale-up, while at low flow rates, the jets fail to impinge in 4X scale-up, and sometimes failing to fill the reactor volume. Iron oxide primary and agglomerate particles are seen to vary with flow rate and reactant concentrations. Largest primary particles (and smallest agglomerates) are obtained at high flow rates and high reactant concentrations, which indicate to size dependent agglomerative tendency of the primary particles. Stabilizers added in situ see limited success. Post-reaction sonication is helpful in dispersing soft agglomerates, but in situ sonication shows no significant reduction in agglomerate size with or without stabilizer. Primary particles are understood to agglomerate due to collisions induced by Brownian motion, simple shear and velocity fluctuations in turbulent flows. These collision mechanisms operate at different length scales in the fluid mass. / Chemical Engineering

Made available in DSpace on 2014-06-11T19:23:30Z (GMT). No. of bitstreams: 0 Previous issue date: 2008-12-19Bitstream added on 2014-06-13T18:09:39Z : No. of bitstreams: 1 canova_alf_me_bauru.pdf: 536650 bytes, checksum: a9187371a18d33b935507b73518a7aa2 (MD5) / Esse trabalho tem por objetivo estudar moléculas confinadas via método de Hartree-Fock, de modo a determinar a energia de ligação e do raio de ligação. Estudamos as moléculas de H- 'H POT. +' e HE- 'H POT. +' incluindo os efeitos de blindagem através da modificação da energia de repulsão nuclear. Essa modificação ocorreu pela introdução do fator de blindagem que, ao ser sucessivamente modificado, permitiu um estudo comparativo do comportamento da energia de ligação e do raio de ligação. A relevância desse trabalho para a área de Ciências e Tecnologia de Materiais deve-se ao fato de que a compreensão e o desenvolvimento de materiais e técnicas dependem não somente das espécies químicas, mas também das ligações químicas, pois ambas determinam as características e as propriedades do material. / The main objective of this work was to study the chemical and physical properties, as the bond distance and energy, of confined atoms via Hartree-Fock method. We studied the H- 'H POT. +' e HE- 'H POT. +' molecules introducing the screening effects via modification of the nuclear repulsion energy between atoms allowing thus to understanding the effects in the bond length and energy. The relevance of this work is of prime importance in material science due to many technological applications as molecules confined to surfaces, in liquid helium, neutral plasma and catalysis. All this applications has a common background of knowledge: the influence of the material physical and chemical properties with the distance and energy between the atoms in the chemical composition of the material.

Esta pesquisa trata de uma análise do trabalho de dez eletricistas que atuam em espaços confinados de redes subterrâneas de distribuição de energia, na Companhia Estadual de Energia Elétrica, Porto Alegre, RS. Foi identificada a demanda ergonômica dos eletricistas, com base em um método participativo (Análise Macroergonômica do Trabalho) de levantamento e avaliação dos dados, que gerou insumos para a melhoria das condições de trabalho e segurança e, conseqüente, promoção de prevenção de acidentes. A pesquisa revelou que os eletricistas consideram como aspectos mais positivos do trabalho os relacionamentos entre chefia, supervisores e colegas. Em contrapartida, apontam problemas críticos de diversas naturezas: biomecânico/posto, organização do trabalho, ambiental e relacionados à empresa. Também foram identificados níveis elevados de demandas físicas e mentais do trabalho, concluindo-se que o medo, evidenciado no discurso dos eletricistas, é referente ao trabalho com eletricidade e não ao trabalho em espaços confinados. Além disso, a pesquisa apontou cinco procedimentos, considerados como padrões mínimos, para a realização de trabalhos seguros em espaços confinados: reconhecimento, monitoramento da atmosfera, ventilação, treinamento e resgate.Apesar dos eletricistas não terem ciência da existência destes procedimentos, os mesmos foram citados, direta ou indiretamente nas entrevistas, como aspectos relevantes ao trabalho, sendo atribuído a maioria deles um baixo nível de satisfação. Com isso, conclui-se que a implantação de um programa de permissão de entrada em espaços confinados, além de promover a segurança neste ambientes tem relação direta com a satisfação dos trabalhadores. / The focus of this dissertation is the work analysis of ten electricians who act in confined space at underground power lines at the Estate Electricity Company in Porto Alegre, RS. It was identified the electricians’ ergonomic demand items. The research was carried out according to the participatory methods of survey and assessment of data, to improvement of safety and work conditions and, therefore, to prevent accidents. The research disclosed that the electricians have the relationship with their superiors, supervisors, and workmates as the most positive aspect of the job. On the other hand, they point out critical problems from different causes: biomechanical, task organization, environmental, and the ones related to the company. Overload regarding physical and mental work demand has been identified, proving that the fear, evident in the professionals’ speech is about the electricity, and not related to confined underground spaces. Besides, the research also displayed five procedures regarded as minimal standards to execute safe work in confined spaces: recognition, testing and monitoring atmosphere, ventilation, training and rescue. Despite the little knowledge electricians have on this criteria, some points of it were reported, some in an indirect way, during the interviews as relevant aspects to the work, being attributed to most of them a low level of satisfaction. Therefore, it comes to the conclusion that the implantation of a Permit-Requires Space Program, besides promoting accidents prevention in these spaces, has a direct relationship with the workers’ satisfaction.

Ce travail de recherche s'intéresse à la dynamique de bulles en ascension à grand nombre de Reynolds dans un liquide fortement confiné entre deux plaques (cellule de Hele-Shaw). Dans le régime étudié, les trajectoires des bulles et leurs déformations sont contenues dans le plan de la cellule. La dynamique essentiellement bidimensionnelle favorise en particulier l'observation d'interactions entre bulles. Cette étude expérimentale comprend donc deux volets : l'analyse de la dynamique d'une bulle isolée et de son sillage et celle des interactions hydrodynamiques entre deux bulles. La cinématique des bulles (forme, trajectoire et vitesse) est mesurée à partir de visualisations par ombroscopie sur une large gamme de tailles caractérisées par un diamètre équivalent dans le plan, noté d. La dynamique des sillages est quant à elle étudiée par Vélocimétrie par Image de Particules (PIV) à Haute Fréquence. Concernant l'étude de la bulle isolée, nous avons exploré la situation où les bulles montent dans un liquide au repos et celle où elles sont soumises à un écoulement descendant à contre-courant. En liquide au repos, pour des bulles de taille suffisante qui ne sont pas mobiles dans l'interstice d'épaisseur e nous avons montré que la vitesse moyenne d'ascension Vb est proportionnelle à (e/d)⅙ √gd, et que le nombre de Reynolds défini par Re=Vbd/v fixe la déformation des bulles. De plus des lois d'échelle simples sont obtenues dans la gamme 1200≤Re≤3000 et e/d ≤ 0,4 pour les grandeurs décrivant les oscillations de trajectoire dans le repère de la bulle. Par ailleurs, des mesures de vitesse nous ont permis de caractériser la structure du sillage associé aux oscillations de trajectoire de la bulle. Nous avons tout d'abord étudié en détail les caractéristiques du détachement tourbillonnaire. Ces mesures de vitesse dans les sillages ont également mis en évidence l'existence de deux dynamiques distinctes sur deux échelles de temps nettement séparées : la période d'oscillation de la bulle et le temps visqueux défini à partir de e. En écoulement à contre-courant, un résultat intéressant consiste en la disparition de la phase intermédiaire d'appariement tourbillonnaire dans l'allée de von Karman de bulles oscillantes pour la plus importante des vitesses du contre-écoulement. La caractérisation de la cinématique des bulles isolées et des perturbations de vitesse qu'elles induisent dans le liquide a permis d'aboutir à des lois d'échelle suffisamment robustes pour pouvoir prédire leur comportement instationnaire simplement à partir de leur taille. Cette connaissance s'avère cruciale dans l'analyse des interactions entre deux bulles pour explorer les écarts de leur comportement cinématique par rapport au cas isolé. Les expériences d'interaction entre deux bulles consistent à injecter deux bulles successives et à observer leur mouvement ainsi que celui qu'elles induisent dans la phase liquide. Le suivi des bulles par ombroscopie permet de distinguer plusieurs modes d'interaction entre les bulles : attraction horizontale, entrainement vertical, éjection du sillage ou rebond, contournement, positionnement préférentiel et coalescence. Certains mécanismes d'interaction ont été plus spécifiquement étudiés à l'aide de mesures par vélocimétrie. Nous avons ainsi pu quantifier l'effet du sillage de la première bulle sur la deuxième, et notamment caractériser l'interaction bulle - tourbillon. / We study the dynamics of bubbles rising in a liquid confined in a thin-gap cell (Hele-Shaw cell of thickness e). In the regime investigated corresponding to high Reynolds numbers, bubble paths and deformations occur in the plane of the cell. This two-dimensional dynamics facilitates the observation of bubbles interaction. The aim of the investigation is twofold: the analysis of the coupling between the motion of an isolated oscillating bubble and its wake, and the analysis of the hydrodynamical interactions between two bubbles. Bubble motions (shape, trajectory and velocity) are measured from visualizations using shadowgraphy for a large range of bubble sizes characterized by their in-plane equivalent diameter d. The behaviour of the wake is explored using High Frequency Particle Image Velocimetry (HF PIV). We investigated the kinematics of an isolated bubble when its size d increases. We showed that the mean vertical velocity of the bubble Vb is proportional to (e/d)⅙ √gd, and that the Reynolds number Re=Vbd/v determines its mean deformation. Simple scaling laws were then obtained in the range 1200≤Re≤3000 and e/d ≤ 0,4 for all the quantities describing the path oscillations of the bubble in its reference frame. Moreover, measurements of the liquid velocity allowed us to characterize the structure of the wake associated to the oscillating bubbles. We first investigated in detail the characteristics of vortex shedding. We then showed that the time evolution of the bubble wake depends on two contrasted time scales. The first corresponds to short times on the order of the period of oscillation and the second to the effect of wall friction becoming predominant for times comparable to the viscous time scale based on the gap thickness e. In the presence of a sufficiently strong counterflow, we observed the disappearance of the intermediate phase of vortex pairing in the wake of an isolated oscillating bubble. The characterization of the bubble kinematics and of the bubble-induced velocity perturbation in the liquid phase for the isolated bubble provided scaling laws robust enough to predict their periodic motion. This knowledge is fundamental for the discussion of hydrodynamical interactions, allowing us to discuss the kinematics of interacting bubbles as compared to their kinematics as isolated bubbles. Experiments consisted in the injection of two successive bubbles in the cell, the observation of their motions and the measurement of the perturbations induced in the liquid phase. Visualizations of the bubbles motions allowed us to observe several types of interactions: horizontal attraction, vertical entrainment, ejection or bouncing, preferential positioning, and coalescence. Some mechanisms occurring during interaction have been more precisely studied using HF PIV, in particular the effect of the wake of the leading bubble on the trailing bubble, and the associated bubble-vortex interaction.

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / In order to assess the use of high grain diets, corn or sorghum offered as the entire form or ground, the termination in male animals in confinement, crossbred dairy origin, an essay was conducted at the Escola de Medicina Veterinária e Zootecnia (EMVZ) the Universidade Federal do Tocantins (UFT), in the municipality of Araguaína, in the North region of Brazil, between October 2013 and January 2014, lasting 109 days. It was used 28 crossbred steers whole, from crosses of European breeds with zebu breeds, with an average age of 30 months and average weight of 238 ± 6,1 kg. Four treatments were tested: MGI) whole corn; MGM) Grounded Corn; SGI) Whole Sorghum; and SGM) Grounded sorghum. These diets were formulated targeting an average daily weight gain of 1,5 kg/day/animal, with 100 % concentrate, on a dry matter basis. After a period of 109 days, the animals were slaughtered and subsequently to this period, were made evaluations of temperature, pH, carcass conformation, based on muscular expression and physiological maturity, based on ossification of the vertebrae and ribs. The marbling assessments, color and texture of meat were held. Chemical composition of the meat was performed on sample taken from caudal face of the Longissimus dorsi. The steaks were undergone by evaluators trained in sensory analysis panel. It was evaluated the levels of dry matter, crude protein, ether extract, neutral detergent fiber, acid detergent fiber, non-fiber carbohydrate, total carbohydrates and total digestible nutrients, and their respective apparent digestibility. It was also evaluated the total weight gain, average daily gain, feed efficiency and feed conversion. The experiment was conducted as a completely randomized design with the treatments distributed in a factorial arrangement 2 x 2, being used seven replications (animals) per treatment. According to analyzes carried out by this study, it is concluded that the best performances of average daily intake, feed conversion and body condition score were obtained in diets that used kernel of corn in the ground form, while the meat and carcass performance, treatment with sorghum grain in the entire form, obtained better results. / Com o objetivo de avaliar o uso de dietas de alto grão, milho ou sorgo, fornecidos nas formas inteira ou moída, na terminação em confinamento de animais machos, mestiços de origem leiteira, foi realizado um experimento na Escola de Medicina Veterinária e Zootecnia (EMVZ) da Universidade Federal do Tocantins (UFT), localizada no município de Araguaína, situada na região Norte do Brasil, entre outubro de 2013 e janeiro de 2014, com duração de 109 dias. Utilizou-se 28 novilhos mestiços inteiros, provenientes de cruzamentos de raças taurinas com raças zebuínas, com idade média de 30 meses e peso médio inicial de 238 ± 6,1 Kg. Foram testados quatro tratamentos, MGI) Milho inteiro; MGM) Milho Moído; SGI) Sorgo inteiro; e SGM) Sorgo Moído, essas dietas foram formuladas visando um ganho de peso médio diário de 1,5 kg/dia/animal, apresentando 100% de concentrado, com base na matéria seca. Depois do período de 109 dias os animais foram abatidos, e posteriormente a este período foram feitas avaliações de temperatura, pH, conformação, baseada na expressão muscular e maturidade fisiológica, baseada na ossificação das vértebras e costelas. Foram realizadas as avaliações de marmoreio, coloração e textura da carne. A composição química da carne foi realizada em amostra retirada da face caudal do Longíssimus dorsi. Os bifes foram submetidos a avaliações através de avaliadores treinados no painel de análise sensorial. Avaliou-se os níveis de matéria seca, proteína bruta, extrato etéreo, fibra em detergente neutro, fibra em detergente ácido, carboidratos não fibrosos, carboidratos totais e nutrientes digestíveis totais, além de suas respectivas digestibilidades aparentes. Também foram avaliados o ganho de peso total, ganho médio diário, eficiência alimentar e conversão alimentar. O experimento foi realizado com delineamento inteiramente casualizado, sendo os tratamentos distribuídos em arranjo fatorial 2 x 2, sendo utilizado sete repetições (animais) por tratamento. De acordo com análises realizadas através desse estudo, conclui-se que os melhores desempenhos de consumo médio diário, conversão alimentar e escore de condição corporal foram obtidos nas dietas que utilizaram grão de milho na forma moída, enquanto que no desempenho de carne e carcaça, o tratamento com grão de sorgo na forma inteira, obteve melhores resultados.

Esta pesquisa trata de uma análise do trabalho de dez eletricistas que atuam em espaços confinados de redes subterrâneas de distribuição de energia, na Companhia Estadual de Energia Elétrica, Porto Alegre, RS. Foi identificada a demanda ergonômica dos eletricistas, com base em um método participativo (Análise Macroergonômica do Trabalho) de levantamento e avaliação dos dados, que gerou insumos para a melhoria das condições de trabalho e segurança e, conseqüente, promoção de prevenção de acidentes. A pesquisa revelou que os eletricistas consideram como aspectos mais positivos do trabalho os relacionamentos entre chefia, supervisores e colegas. Em contrapartida, apontam problemas críticos de diversas naturezas: biomecânico/posto, organização do trabalho, ambiental e relacionados à empresa. Também foram identificados níveis elevados de demandas físicas e mentais do trabalho, concluindo-se que o medo, evidenciado no discurso dos eletricistas, é referente ao trabalho com eletricidade e não ao trabalho em espaços confinados. Além disso, a pesquisa apontou cinco procedimentos, considerados como padrões mínimos, para a realização de trabalhos seguros em espaços confinados: reconhecimento, monitoramento da atmosfera, ventilação, treinamento e resgate.Apesar dos eletricistas não terem ciência da existência destes procedimentos, os mesmos foram citados, direta ou indiretamente nas entrevistas, como aspectos relevantes ao trabalho, sendo atribuído a maioria deles um baixo nível de satisfação. Com isso, conclui-se que a implantação de um programa de permissão de entrada em espaços confinados, além de promover a segurança neste ambientes tem relação direta com a satisfação dos trabalhadores. / The focus of this dissertation is the work analysis of ten electricians who act in confined space at underground power lines at the Estate Electricity Company in Porto Alegre, RS. It was identified the electricians’ ergonomic demand items. The research was carried out according to the participatory methods of survey and assessment of data, to improvement of safety and work conditions and, therefore, to prevent accidents. The research disclosed that the electricians have the relationship with their superiors, supervisors, and workmates as the most positive aspect of the job. On the other hand, they point out critical problems from different causes: biomechanical, task organization, environmental, and the ones related to the company. Overload regarding physical and mental work demand has been identified, proving that the fear, evident in the professionals’ speech is about the electricity, and not related to confined underground spaces. Besides, the research also displayed five procedures regarded as minimal standards to execute safe work in confined spaces: recognition, testing and monitoring atmosphere, ventilation, training and rescue. Despite the little knowledge electricians have on this criteria, some points of it were reported, some in an indirect way, during the interviews as relevant aspects to the work, being attributed to most of them a low level of satisfaction. Therefore, it comes to the conclusion that the implantation of a Permit-Requires Space Program, besides promoting accidents prevention in these spaces, has a direct relationship with the workers’ satisfaction.

O propósito deste trabalho é aumentar o conhecimento existente sobre as interações dielétricas da água confinada em materiais hidrofílicos, no regime de baixas temperaturas. Os materiais hidrofílicos (sílica gel, gesso, colágeno e álcool polivinílico - PVA) foram analisados com os recursos disponíveis na técnica de Espectroscopia de Impedância - permissividade dielétrica e impedância elétrica. Como objetivo especifico procurou-se estabelecer experimentalmente o papel das ligações hidrogênio nos processos de condução observados na água confinada e verificar a existência da transição dinâmica da água super-resfriada em T = -45ºC (228K). As substâncias examinadas possuem redes ou cadeias moleculares, com grupos polares superficiais capazes de se ligarem às moléculas de água por meio de ligações hidrogênio. Em espaços restritos de natureza hidrofílica, a água pode ser super-resfriada além do ponto de nucleação homogênea, permanecendo líquida para temperaturas inferiores a 0ºC. O entendimento de sistemas envolvendo materiais hidrofílicos - tais como sólidos, géis e macromoléculas - e a água, contribui para o desenvolvimento de novos materiais e para o entendimento dos sistemas vivos. De acordo com os resultados obtidos a condução dos íons na água confinada se dá por meio da rede formada, via ligações hidrogênio, entre as moléculas de água e a cadeia dos materiais. O espectro elétrico dos materiais estudados exibe dois processos de condução, comuns a todas as substâncias. O primeiro, é influenciado pelo nível de hidratação das amostras e está relacionado as moléculas de água distantes das superfícies. O segundo, é próprio da água confinada e possui tempos de relaxação elétricos com transições observadas em -60ºC (210K) na sílica gel, e -45ºC nos outros materiais. Também constatou-se que o tamanho da cadeia polimérica do PVA altera a dinâmica do confinamento de água: cadeias de menor peso molecular não são capazes de gerar sítios que propiciem o confinamento da água. / This work aims to increase the existing knowledge on the dielectric interactions of water confined in hydrophilic materials at low temperatures. The hydrophilic materials (silica gel, gypsum, collagen and polyvinyl alcohol - PVA) were studied with the available functions of Impedance Spectroscopy - dielectric permittivity and electrical impedance. The specific goal of this thesis is to establish the role of hydrogen bonds in the conduction processes observed in confined water and to verify the existence of the supercooled water dynamic crossover at T = -45 ºC (228K). The chosen substances have molecular chains or networks with polar surface groups connected to water molecules through hydrogen bonds. When confined in small geometries, water does not crystallize and can be supercooled bellow its homogeneous nucleation temperature. This allows the indirect investigation of supercooled confined water. The studies of systems involving hydrophilic materials - such as solids, gels and macromolecules - and water, contributes to the development of new materials and to the understanding of living systems. This study demonstrated that the conduction in the confined water occurs through the network formed by hydrogen bonds between water molecules and the chain materials. The impedance spectra of all material exhibits two conduction processes common to all the analyzed samples. While the level of hydration of the samples can influence the process of higher frequencies, the one found in lower frequencies is independent of the amount of water in the samples. The first was associated to bulk water molecules and the second is related to confined water and show the expected dynamic crossover. In addition, the size of the PVA polymeric chain alters the dynamics of water: lower molecular weight polymers are not capable of displaying the supercooled dynamic crossover.