O Método dos Elementos Finitos é a forma mais difundida de análise estrutural numérica, com aplicações nas mais diversas teorias estruturais. Contudo, no estudo das cascas e alguns outros usos, suas deficiências impulsionaram a pesquisa em outros métodos de resolução de Equações Diferenciais Parciais. O presente trabalho utiliza uma dessas alternativas, o Método de Galerkin Livre de Elementos (Element-Free Galerkin) para estudar as cascas. Inicia com a observação da aproximação usada no método, os Moving Least Squares e os Multiple-Fixed Least Squares. A seguir, estabelece uma formulação que combina a teoria de placas moderadamente espessas de Reissner-Mindlin à teoria da Elasticidade Plana e se utiliza da aproximação estudada para analisar placas e chapas deste tipo. Depois, expõe uma teoria geometricamente exata de cascas inicialmente curvas onde as curvaturas iniciais são impostas como deformações livres de tensão a partir de uma configuração de referência plana. Tal teoria exclui a necessidade de coordenadas curvilíneas e consequentemente da utilização de objetos como os símbolos de Cristoffel, já que todas as integrações e imposições são feitas na configuração plana de referência, em um sistema ortonormal de coordenadas. A imposição das condições essenciais de contorno é feita por forma fraca, resultando em um funcional híbrido de deslocamentos que permite a maleabilidade necessária ao uso dos Moving Least Squares. Esse trabalho se propõe a particularizar tal teoria para o caso de pequenos deslocamentos e deformações (linearidade geométrica), mantendo a consistência das definições de tensões e deformações generalizadas enquanto permite uma imposição da forma fraca resultante, depois de discretizada, por um sistema linear de equações. Por fim, exemplos numéricos são usados para discutir sua eficácia e exatidão. / The Finite Element Method is the most spread numerical analysis tool, applied to a wide range of structural theories. However, for the study of shells and other problems, some of its deficiencies have stimulated research in other methods for solving the derived Partial Differential Equations. The present work uses one of those alternatives, the Element Free Galerkin Method, for the study of shells. It begins with the observation of the approximation used in the method, Moving Least Squares and Multiple-Fixed Least Squares. Then, it establishes a formulation that combines the Reissner-Mindlin moderately thick plate theory with plane elasticity, and uses the proponed approximation to analyze such plates and stabs. Afterwards, it demonstrates a geometrically exact shell theory that accounts for initial curvatures as a stress-free deformation from a flat reference configuration. Such theory precludes the use of curvilinear coordinates and, subsequently, the use of objects such as Cristoffel symbols, as all integrations and impositions are done in the flat reference configuration, in an orthogonal frame. The essential boundary conditions are imposed in a eak statement, rendering a hybrid displacement functional that provides the necessary conditions for the use of Moving Least Squares. This works main objective is the particularization of this theory for the small displacement and strains assumption (geometrical linearity), keeping the consistent definition of generalized stresses and strains, while allowing the imposition of the discretized weak form through a system of linear equations. Lastly, numerical simulations are carried out to assess the methods efficiency and accuracy.

Orientador: Isaias Vizotto / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Civil, Arquitetura e Urbanismo / Made available in DSpace on 2018-08-23T04:16:31Z (GMT). No. of bitstreams: 1 ChoquehuancaCondori_MiriamPatricia_M.pdf: 4529351 bytes, checksum: a025230362e01b26a4c17a7775ab9818 (MD5) Previous issue date: 2013 / Resumo: O objetivo deste trabalho é apresentar a teoria atual e estudar o comportamento dinâmico de reservatórios cilíndricos de concreto armado, apoiados no solo, para armazenagem de líquidos e submetido a ações sísmicas, baseado nas normas vigentes nos EUA (ACI 350), Europa (EUROCODE 8), Peru (NTE 030) e Brasil (NBR 15421). São utilizados diferentes tipos de análises a fim de verificar, através da comparação de resultados, se as normas e recomendações disponíveis hoje em dia são equivalentes e adequadas para a realidade brasileira. Entre os modelos para a análise hidrodinâmica temos os modelos de Malhortra, Haroun, Newmark & Rosemblueth e o modelo mecânico de G. W. Housner, sendo este último o procedimento para projetos sísmicos mais comuns para reservatórios rígidos onde a pressão hidrodinâmica do líquido é considerada dividida em duas partes: uma pressão impulsiva (impacto do líquido) e outra parte convectiva (oscilação do líquido). No Brasil não existe uma norma especifica para o projeto de reservatórios de concreto armado. A utilização da NBR 15421 "Estruturas Resistentes a Sismo-Procedimento," poderia ser insuficiente para o projeto, e possivelmente ao complementá-la com as normas sugeridas neste trabalho (ACI 350 e EUROCODE 08) há a possibilidade de encontrar contradições, ou, bem, diferenças significativas nos resultados. É apresentado o procedimento de projeto sísmico por meio de um caso pratico, além dos modelos numéricos tridimensionais com a ajuda do programa SAP2000. Considerando as propriedades elásticas e geométricas do material, a geometria do reservatório de armazenagem e o espectro de resposta da análise modal, são avaliados a força cortante e o momento na base e altura máxima de onda, através da ACI 350.3-06, EUROCODE 08, NTE 030 e NBR 15421. É ainda apresentada a comparação dos procedimentos propostos pelas quatro normas, e a influencia que cada uma delas representa neste tipo de análise. As normas americanas e européias são consideradas por serem duas referências importantes na análise dinâmica de reservatórios de concreto / Abstract: The purpose of this work will be to present the current theory and study the dynamic behavior of a reinforced concrete tank, with cylindrical form, supported in the floor, for the storage of liquid, based on the current codes in the USA (ACI 350), EUROPA (EUROCODE 8), Peru (NTE 030) and Brazil (NBR 15421), using different analysis types in order to verify by comparing results, if the codes and recommendations today are equivalent and appropriate for the Brazil reality. For the hydrodynamic analysis may mention the Malhortra, Haroun, Newmark & Rosemblueth models and the mechanic model proposed by G. W. Housner, the latter being the most common procedure for rigid tank where the hydrodynamic pressure of the liquid is considered into two parts: a impulse pressure (impulse of the liquid) and a convective pressure (oscillation of the liquid). In Brazil there is no specific code for the design of reinforced concrete tanks. The use the code of Brazil: NBR 15421 Estruturas Resistentes a Sismo - Procedimento" could be insufficient for the project, and possibly complementing with the suggested codes in this work (ACI 350 and EUROCODE 08 codes), there are some possibilities to find contradictions, or, significant differences in the results. It presents the seismic design procedure through a practical case, besides presenting three-dimensional numerical models with the help of the SAP2000 program, considering the geometric and elastic properties of the material, the geometry of the storage tank and the spectral modal dynamic analysis. Are evaluated the sheer force, moment at the base and maximum wave height, by ACI 350.3-06, EUROCODE 08, NTE 030 and NBR 15421. It will be presented the comparison of the procedures proposed by codes and the influence of each one of them presents in this analysis type. The American and European code are considered because they are an important reference in the dynamic analysis of concrete tanks / Mestrado / Estruturas / Mestra em Engenharia Civil

Orientador: Isaias Vizotto / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Civil, Arquitetura e Urbanismo / Made available in DSpace on 2018-08-23T06:21:27Z (GMT). No. of bitstreams: 1 CaycedoGarcia_MayaSian_M.pdf: 6369697 bytes, checksum: 0216dc84287a93e820b62482c1b9b7d1 (MD5) Previous issue date: 2013 / Resumo: Através do uso de modelos físicos reduzidos e de simulações computacionais, este trabalho tem como objetivo a avaliação do comportamento mecânico das estruturas em casca de formas livres de base hexagonal. Os modelos reduzidos são submetidos a ensaios no túnel de vento de camada limite atmosférica, e às correspondentes simulações computacionais, extraindo-se dados dos coeficientes de pressão interna e externa, considerando-se os regimes laminar e turbulento. A obtenção dos coeficientes de pressão permite avaliar o comportamento da estrutura dependendo do posicionamento da abertura dominante nos casos mais críticos de sucção e pressão. A análise dos coeficientes de pressão causados pela ação do vento em edificações é um aspecto fundamental no estudo das forças que atuam em estruturas. No caso particular das construções dos tipos de cascas finas, a análise dos coeficientes de pressão permite analisar e projetar estas estruturas corretamente aproveitando suas características geométricas. Os ensaios desta pesquisa foram realizados no túnel de vento LACAF da UNICAMP, utilizando-se os modelos reduzidos construídos com materiais compostos de fibra de vidro e resina, FERREIRA (2013), e produzidos a partir dos modelos computacionais desenvolvidos por VIZOTTO (1993). Durante os ensaios no túnel de vento, foram realizadas medições de pressão em vários pontos dos modelos, tanto na superfície externa como interna da estrutura submetida à ação do vento em regime laminar e turbulento, nas três situações criticas da abertura: estrutura fechada submetida à ação do vento a 0º e 90º; estrutura com uma abertura submetida à ação do vento a barlavento (0º) e sotavento (180º); e, com duas aberturas, submetida à ação do vento a barlavento (0º) e paralelo às aberturas (90º). Os resultados dos ensaios são apresentados em curvas isobáricas e analisados através do uso de gráficos comparativos para os casos dos regimes laminar e turbulento para cada caso ensaiado. Os modelos computacionais para realizar as simulações foram baseados nos resultados dos experimentos com modelos em túnel de vento, considerando as diversas combinações nos regimes laminar e turbulento, foram gerados através da ferramenta da fluidodinâmica computacional utilizando o modelo de turbulência "SST" no software Ansys (CFX) no laboratório de informática da FEC - UNICAM. Dos resultados obtidos experimentalmente dos coeficientes de pressão pode-se observar a máxima sucção na estrutura para o caso de uma abertura com o vento atingindo à estrutura na direção de barlavento no regime turbulento e a maior pressão é observada para o caso de duas aberturas com o vento atingido paralelo às aberturas. Dos dados obtidos numericamente em relação aos dados experimentais certificasse que existe uma grande semelhança, permitindo o uso da fluodinâmica computacional como ferramenta para a análise da ação do vento em estruturas tipo casca. Cabe notar que a indisponibilidade de dados para os coeficientes de pressão para carregamentos devidos ao vento nas estruturas com este tipo de geometria cria a necessidade de proporcionar e divulgar informações, metodologias e ferramentas, como a configuração dos modelos matemáticos, que permitam aos engenheiros obter as forças devidas ao vento utilizadas para a simulação de carregamentos em projetos reais / Abstract: Through the use of reduced physical models and computer simulations, the objective of this project is to assess the mechanical behavior of free form shell type structures with hexagonal base. The reduced models are subject to atmospheric boundary layer wind tunnel tests, while computer simulations are run in parallel, that provide internal and external pressure coefficient data applicable to the structures in question under the influence of both laminar and turbulent flow regimes. The obtained pressure coefficients allow the assessment of the behavior of the structure as a function of the position of the predominant opening in the most critical suction and pressure cases. The analysis of the pressure coefficients caused by wind loads in construction is a critical area of the structural force analysis in buildings and structures. In the particular case of thin walled shell type constructions, pressure coefficient analysis is the main driver for the correct design and planning of these structures, taking advantage of their geometrical features The tests were conducted in the wind tunnel at LACAF at the UNICAMP using scale models built out of fiberglass and resin, Ferreira (2013), and produced as result of the use of computer models developed by Vizotto (1993). The wind tunnel tests provided pressure measurements at various points of the structures subjected in the three following critical scenarios of predominant aperture: completely closed structure subjected to wind loads at 0 and 90 degrees, structure with one open subjected to wind loads at leeward (180°) and windward (0°) and structure with two opens subjected to wind loads at leeward (180°) and parallel to the apertures (90°). The test results are presented in isobaric graphs and are then analyzed in comparative graphics for each tested scenario. The computer models used to run the simulations are based on the empirical results obtained in wind tunnel tests using reduced size models, considering the various possible combinations, and were generated using the turbulence model "Shear Stress Transport Model" of the dynamic fluid analysis software tool Ansys (CFX) at the IT laboratory of the FEC - UNICAMP. The comparison of the numerical data with the experimental data certifies that there are a lot of similarities. Therefore, computer models can be used in order to project free form shell type structures and evaluate their behavior under wind loads. Finally, it is of significant relevance the fact that pressure coefficient data applicable to structures with this type of geometry subject to wind loads is not readily available. Therefore, it is necessary to provide and divulge information, methodologies and tools, such as the configuration of mathematical models, which will enable engineers to obtain more accurate data of wind-load forces used for the simulation of loads on free form shell type structures / Mestrado / Estruturas / Mestra em Engenharia Civil

Orientador: Isaias Vizotto / Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia Civil, Arquitetura e Urbanismo / Made available in DSpace on 2018-08-24T02:40:36Z (GMT). No. of bitstreams: 1 Ferreira_AntonioMario_D.pdf: 9010854 bytes, checksum: 0b548385f37faa810cae541ae265ec42 (MD5) Previous issue date: 2013 / Resumo: Este trabalho realiza uma análise numérica e experimental do comportamento de estruturas em cascas de formas livres sob a ação do vento. Inicialmente foram gerados modelos computacionais de formas otimizadas, sendo uma casca de planta pentagonal e outra hexagonal. Na sequência foram construídos modelos físicos reduzidos em laboratório e submetidos a uma série de ensaios em túnel de vento. E, finalmente foram realizadas simulações numéricas dessas estruturas submetidas à ação do vento utilizando o programa computacional ANSYS-CFX do Laboratório de Informática da FEC-UNICAMP. Os modelos físicos reduzidos analisados foram gerados utilizando o software ANSYS e o programa computacional desenvolvido por Vizotto (1993), e construídos no Laboratório de Automação e Prototipagem para Arquitetura e Construção (LaPAC) da FEC-UNICAMP, utilizando inicialmente isopor de alta densidade, que foi posteriormente empregado para execução de fôrmas de concreto armado para moldar os modelos finais em material composto por fibra de vidro e resina, para serem ensaiados no túnel de vento do Laboratório de Conforto Ambiental e Física Aplicada (LaCAF) da FEC-UNICAMP. Os testes no túnel de vento do LaCAF foram realizados em dezesseis fases, sendo compostas por análises para obtenção dos coeficientes de pressão externa e interna, com ventos em regime laminar e turbulento, a 0º e 36º para a casca com forma de planta pentagonal, e a 0º e 30º para a casca com forma de planta hexagonal. Para análises por meio de simulação fluidodinâmica computacional pelo ANSYS-CFX, foi realizada inicialmente uma análise comparativa para os resultados dos coeficientes de pressões externas de um modelo de cúpula sobre o terreno da NBR 6123:1988. O software ANSYS-CFX demonstrou ótima eficiência na configuração realizada, apresentando resultados muito próximos aos da norma brasileira, e essa configuração também foi utilizada na validação física entre os ensaios no túnel de vento e as simulações pelo ANSYS-CFX. É sugerida a utilização dos dados finais na elaboração de normas específicas e uma configuração adequada e segura dentro das características consideradas para a utilização do software ANSYS-CFX como ferramenta para obtenção de coeficientes de pressões / Abstract: This work performs a numerical and experimental analysis of behavior of structures in free form shells about wind action. At first, computational models were generated in optimized forms, being one shell of pentagonal shape and another one hexagonal. After this, reduced physical models were built in laboratory and subjected to several tests in the tunnel of wind. Finally, numerical analyzes of these structures subjected to wind action were achieved using ANSYS computational program from FEC-UNICAMP computer laboratory. Two reduced physical models were analyzed, using the software ANSYS and the computational program that was developed by VIZOTTO I. (1993), and built at the Laboratory of Automation and Prototyping for Architecture and Construction site (LaPAC) from FECUNICAMP. The techniques: one hexagonal and another pentagonal, both made, at first, with Styrofoam in large dense, that was applied to execution of forms of concrete to be sculptured and finalized as a material composed of glass fiber and resin for future test in the wind tunnel at (LaCAF) from FEC-UNICAMP Environmental Comfort and Applied Physics Laboratory. The tests at the wind tunnel from LaCAF were made into sixteen phases, composed by analysis to obtain the coefficients of outside and inside pressure with wind in turbulent and laminar state, at 0º and 30º for hexagonal shape and turbulent and laminar, at 0º and 36º for pentagonal shape. To analyze by simulation computational fluid dynamics by ANSYS-CFX, at first were achieved a comparative analysis to the results of coefficients of outside pressure from a model of dome on the land from NBR 6123:1980. The software ANSYS-CFX showed an excellent efficiency on the made configuration, showing results very closed to the Brazilian rule, and this configuration also was used in the physical validation between the tests at wind tunnel and the simulations by ANSYS-CFX. It is suggested the usage of final data on specific standard preparation and safe configuration for ANSYS software application as a tool to achieve pressure coefficients / Doutorado / Estruturas / Doutor em Engenharia Civil

Orientador: Renato Pavanello / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Mecanica / Made available in DSpace on 2018-08-04T03:07:11Z (GMT). No. of bitstreams: 1 Pinheiro_RodrigoPostal_M.pdf: 5880905 bytes, checksum: 96b1e181ab7c3d3364510f7d9a656684 (MD5) Previous issue date: 2004 / Resumo: Neste trabalho é apresentada uma implementação de uma família de elementos finitos de casca para problemas dinâmicos transientes com integração explícita. Para isto, são usados um algoritmo de integração do tempo baseado no método das diferenças centrais e duas formulações de elementos finitos de casca com integração reduzida uniforme e controle de modos espúrios de deformação por perturbação. Usa-se um referencial co-rotacional como auxílio à representação cinemática das cascas. São considerados problemas com não linearidades geométrica e de material. A implementação é feita de forma modular, num paradigma de programação estruturada, porém incorporando conceitos de orientação à objetos, de modo a proporcionar uma fácil adaptação a outras aplicações bem como facilidades de expansão e adição de novas funcionalidades / Abstract: Within this work, an implementation of a shell finite element family for transient dynamics with explicit integration is presented. A computational implementation is created using a time integration algorithm based on the central difference method and two shell finite element formulations with uniform reduced integration and a perturbation based hourglass control. This implementation is made in a modular approach, under a structured programming paradigm, but using object oriented concepts, providing a core that can be adapted for other applications and expanded with new features / Mestrado / Mecanica dos Sólidos e Projeto Mecanico / Mestre em Engenharia Mecânica

Au cours de la Néolithisation au Proche-Orient, les bouleversements majeurs survenus au niveau de l’organisation socio-économique des communautés humaines (sédentarisation, agriculture et élevage) se sont accompagnés de changements dans le domaine techno-symbolique. Le présent travail a permis de caractériser l’une des principales manifestations matérielles dans ce domaine, les ornements personnels, à travers l’étude des éléments de parure de six sites syriens couvrant la période entre le 12e et le 6e millénaire avant J.-C. Dans une démarche méthodologique visant à traiter la grande diversité des objets archéologiques, du coquillage à la turquoise en passant par l’os et l’argile, plusieurs protocoles d’identification des matériaux, de classification morpho-typologique et d’analyse tracéologique ont été élaborés. L’analyse des objets de parure selon cette approche intégrative a permis de mettre en évidence l’évolution des formes recherchées et des matériaux utilisés depuis le Natoufien final jusqu’au PPNB récent, mais aussi des développements et des innovations techniques concernant notamment le traitement des roches dures comme la cornaline. Grâce à l’étude des contextes archéologiques et à la reconstitution de certaines parures, les fonctions de ces objets chez les premières sociétés néolithiques ont pu être en partie identifiées. Ainsi, durant le PPNA, les parures pouvaient marquer une appartenance identitaire, parallèlement à des parures « rituelles » qui pourraient être liées à la sphère symbolique propre à cette période. A partir du PPNB moyen les parures sont aussi associées à la mort et à des pratiques funéraires particulières. Les hypothèses proposées par cette thèse ouvrent des perspectives de recherche qui pourront être explorées en élargissant le corpus aux régions adjacentes (Anatolie, Jordanie, etc.) et à des périodes plus récentes. / During the neolithization process in the Near East, alongside the major shifts occurring in the socio-economic organization of the human communities (sedentism, agriculture and husbandry) changes also impacted the techno-symbolic world. The present work aims to characterize and understand one the main material expression in this domain, the personal adornments, by the study of bead assemblages from six Syrian sites dating from the 12th to the 6th millennium cal BC. In order to deal with the great diversity of the archaeological items, e.g. from shell to turquoise beads through bone pendants and clay objects, several methodological protocols of identification, morpho-typological classification and use-wear analysis have been elaborated. The analysis of the beads using this combination of approaches has brought to light the evolution in the conception and use of different shapes, types and materials for this purpose from the final Natufian period to the Late PPNB, as well as the technological development and improvements regarding particularly the transformation of hard stones such as the carnelian. Through the study of the archaeological contexts and the reconstitution of some ornaments, the functions of these objects have been partly addressed. Thus, during the PPNA, the ornaments expressed a social and cultural group affiliation, while from the Middle PPNB onwards they were also associated to the death and to particular funeral rituals. The hypothesis proposed by this work offers promising research perspectives which can be explored by extending the corpus to the adjacent areas (Anatolia, Jordan, etc.) and later periods.

This research evaluates two different Biological Nitrogen Removal (BNR) systems for enhanced nitrogen removal in decentralized wastewater treatment. The first study evaluated the performance of Hybrid Adsorption and Biological Treatment Systems (HABiTS) at the pilot scale with and without stage 1 effluent recirculation. HABiTS is a system developed at the bench scale in our laboratory and was designed for enhanced BNR under transient loading conditions. It consists of two stages; an ion exchange (IX) onto clinoptilolite media coupled with biological nitrification in the aerobic nitrification stage 1 and a Tire-Sulfur Adsorption Denitrification (T-SHAD) system in the anoxic denitrification stage 2. The T-SHAD process incorporates NO3- adsorption onto tire chips and Sulfur Oxidizing Denitrification (SOD) using elemental sulfur as the electron donor for NO3- reduction. Previous bench scale studies evaluated HABiTS performance under transient loadings and found significantly higher removal of nitrogen with the incorporation of adsorptive media in stage 1 and 2 compared with controls (80% compared to 73%) under transient loading conditions. In this study, we hypothesize that a HABiTS system with effluent recirculation in nitrification stage 1 may enhance nitrogen removal performance compared to that without recirculation. The following were the expected advantages of Stage 1 effluent recirculation for enhanced nitrogen removal: 1) Pre-denitrification driven by the mixture of nitrified effluent from stage 1 with high concentrations of biochemical oxygen demand (BOD) septic tank effluent. 2) Moisture maintenance in stage 1 for enhanced biofilm growth. 3) Increased mass transfer of substrates to the biofilm in stage 1. 4) Decreased ratio of BOD to Total Kjeldahl Nitrogen (TKN) in the influent of stage 1. Two side-by-side systems were run with the same media composition and fed by the same septic tank. One had a nitrification stage 1 effluent recirculation component (R-system), which operated at a 7:1 stage 1 effluent recirculation ratio for the first 49 days of the study and at 3:1 beginning on day 50 and one was operated under forward flow only conditions (FF-system). The R system removed a higher percentage of TIN (35.4%) in nitrification stage 1 compared to FF (28.8%) and had an overall TIN removal efficiency of 88.8% compared to 54.6% in FF system. As complete denitrification was observed in stage 2 throughout the study, overall removal was dependent on nitrification efficiency, and R-1 had a significantly higher NH4+ removal (87%) compared to FF-1 (70%). Alkalinity concentrations remained constant from stage 1 to stage 2, indicating that some heterotrophic denitrification was occurring along with SOD, as high amounts of sCOD leached from the tire chips in the beginning of the study, reaching sCOD concentrations of 120-160 mg L-1 then decreasing after day 10 of operation of stage 2. Sulfate concentrations from stage 2 for each side were low until the last 10 days of the study, with an average of 16.43 ± 11.36 mg L-1 SO42--S from R-2 and an average of 16.80 ± 7.98 SO42--S for FF-2 for the duration of the study, however at the end of the study when forward flow rates increased, SO42--S concentrations increased to 32 mg L-1 for R-2 and 40 mg L-1 for FF-2. Similar performance was observed in the FF system as the bench scale reactor tests. The second part of the research focused on the findings from a study of a Particulate Pyrite Autotrophic Denitrification (PPAD) process that uses pyrite as the electron donor and nitrate as the terminal electron acceptor in upflow packed bed bioreactors. The advantages of using pyrite as an electron donor for denitrification include less sulfate production and lower alkalinity requirements compared with SOD. The low alkalinity consumption of the PPAD process led to comparison of PPAD performance with and without oyster shell addition. Two columns were operated side-by-side, one packed with pyrite and sand only (P+S), while another one was packed with pyrite, sand and oyster shell (P+S+OS). Sand was used as a nonreactive biofilm carrier in the columns. My contribution to this research was to carry out Scanning Electron Microscopy-Energy-Dispersive X-Ray Spectroscopy (SEM-EDS) analysis to support the hypothesis that oyster shell contributes to nitrogen removal because it has a high capacity for biofilm attachment. SEM analysis showed that oyster shell has a rough surface, supported by its high specific surface area, and that there was more biofilm attached to oyster shell than pyrite or sand in the influent to the column. EDS results showed a decrease in atomic percentages for pyrite sulfur in the effluent of both columns (59.91% ± 0.10% to 53.94% ± 0.37% in P+S+OS column and to 57.61% ± 4.21% in P+S column). This finding indicated that sulfur was oxidized more than iron and/or the accumulation of iron species on the pyrite surface and supports the coupling of NO3- reduction with pyrite oxidation.

This thesis deals with the topology optimization of plate and shell structures. The shell structures are modeled as plate-like at facets. Firstly, the formulation of the topology optimization problem is presented in an introductory chapter, which introduces two frequently used topology optimization algorithms (being the optimality criterion and the method of moving asymptotes). Examples of applications are shown, and filtering schemes are introduced. Secondly, the derivation of the finite element formulation and interpolation of plates is presented. Both a shear rigid Kirchoff plate element and a shear flexible Mindlin element are considered. The latter element uses substitute shear strains to overcome locking; hence reduced integration is not necessary, as is normally required when shear flexible plate elements are used in topology optimization. The effect of both element formulations on optimal topology is then illustrated. The results reveal the notable effect of through thickness shear on optimal topolog. Thirdly, a at shell element is constructed by combining the plate elements with a membrane element with drilling degrees of freedom. (The membrane is not discussed in any detail.) To illustrate the topology optimization of shell structures, the so-called Scordelis-Lo roof is then selected as an example problem. The analysis includes an assessment of the effect of eccentric stiffeners or ribs on optimum topology. / Dissertation (Master of Engineering)--University of Pretoria, 2007. / Mechanical and Aeronautical Engineering / unrestricted

A modified oil-in-water emulsion process was developed to produce novel microporous hemi-spherical polycaprolactone (PCL) microparticles called “hemi-shells”. Through the addition of a porogen such as sodium bicarbonate into the PCL-dichloromethane oil phase and emulsification in an acidic polyvinyl alcohol aqueous phase, microporous hemi-shells formed as dichloromethane evaporated. Carbon dioxide gas evolution from the porogen reaction with the acidic aqueous phase created particles with an externally microporous shell and a large internal cavity. The hemi-shells were characterized by various methods, including scanning electron microscopy and optical microscopy which were specifically used to quantify the hemi-shell yield. The final number-average particle yield of the optimised manufacturing method for particle manufacture in the 50-200 micron size range was 84%. The number-average hemi-shell yield in the same size range was 41%. These novel microparticles have potential applications in tissue engineering and drug delivery / Dissertation (MEng)--University of Pretoria, 2011. / Chemical Engineering / unrestricted

Orientador : Enrique Ortega Rodriguez / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia de Alimentos / Made available in DSpace on 2018-08-03T14:53:32Z (GMT). No. of bitstreams: 1 CcopaRivera_ElmerAlberto_M.pdf: 3016534 bytes, checksum: be45f6b4596e6a80a50bf600c5d86310 (MD5) Previous issue date: 2003 / Resumo: O estudo da qualidade da água em reservatórios naturais ou artificiais constituise de suma importância para impedir a eutrofização cultural e desenvolver projetos para usos múltiplos. Segundo Kent e Odum (2000) a compreensão da eutrofização cultural é um problema importante no desenvolvimento da interface entre civilização e meio ambiente. Através do conhecimento dos diagramas de fluxo de funcionamento do reservatório e da hierarquia dos fatores que atuam no mesmo, pode-se propor sistemas de manejo com o objetivo de manter a qualidade da água. A energia é o fator limitante mais relevante para um ecossistema, e o conceito de fluxo de energia proporciona não somente meios para comparar diversos ecossistemas, mas também possibilita uma avaliação relativa de cada componente do sistema. Assim, no presente trabalho, utilizando a linguagem de fluxos de energia desenvolvida por Odum (1983), propõe-se representar um reservatório como um sistema. Este sistema fornece uma visão geral da sua estrutura e suas funções, além de organizar dados e conceitos para a compreensão da eutrofização. Dois modelos foram avaliados e simulados no tempo para considerar questões relacionadas ao processo continuo de entrada de fósforo no sistema a longo prazo e o metabolismo diário do reservatório. Os modelos foram testados com base nos dados observados no Reservatório do Lobo. Verificase a partir do trabalho, que utilizando a linguagem de fluxos de energia como ferramenta da ecologia de sistemas, é viável a construção de modelos para representar estruturas e funções importantes do comportamento sistêmico do reservatório facilitando a compreensão dos sistemas reais. Os modelos sistêmicos são ótimos instrumentos de integração de informações e dados de um determinado ambiente e serve também para testar algumas hipóteses que são difíceis de realizar no campo, transformando resultados numéricos em mensagens significativas, melhorando a precisão das discussões teóricas / Abstract: The study of the water quality in natural or artificial reservoirs is constituted of utmost importance to hinder cultural eutrophication and develop projects for multiple uses. According to Kent et al. (2000) the understanding of cultural eutrophication is an important problem in developing interfaces between civilization and environment. Through the knowledge of reservoir functioning flow diagram and the hierarchy of the factors that act on this it can be proposed management systems with the objective of maintain the quality of water. The energy is the more relevant limit factor for an ecosystem, and the flow energy concept provides not only ways to compare diverse ecosystems, but also enables a relative evaluation of each component of the system. Thus in this present study utilizing the energy fluxes language developed by Odum (1983) it proposes to represent a reservoir as a system. This system provides a general view of reservoir structure and its functions beyond organizing dates and concepts for the eutrophication understanding. Two models had been evaluated and simulated in the time to consider questions related to the process. This process consists to keep inflow of phosphorus in the system in the long term and thereservoir daily metabolic. The models were tested on the basis of the data observed in the Lobo Reservoir. It is verified from the work, that the use of energy flows language, as a tool of the ecology of systems, makes possible the construction of models to represent structures and important functions of the water reservoir system. In this manner the understanding of the real system is facilitated. The systems models are excellent instruments of integration of information and society and can serve to test hypotheses that are difficult to carry out in the field, transforming numerical results into significant messages to theoretical research and for regional planning / Mestrado / Mestre em Engenharia de Alimentos