Estuaries are among the most productive and diverse of aquatic habitats supporting a rich variety of plants and animals. They are nursery areas for many species of fish harvested by recreational and subsistence anglers. The Swartkops River Estuary (SRE) is situated approximately 10 km north-east of Port Elizabeth and the only major well-preserved estuary within a city, thus unique to South Africa. The SRE is surrounded by highly urbanized and industrialized regions in the Eastern Cape. The aim of this study was to determine and interpret the presence, levels, and distribution of selected priority pollutants in the food web of the SRE. Different components within the SRE were analysed for the presence of environmental contaminants. Seven sites were selected, some coinciding with previous studies in the SRE. Three of these sites are major discharge points that discharge directly into the estuary. Sediment, mud prawn, sand gobies, bird eggs, and various fish species were analysed. Samples were collected in the middle and lower reaches of the estuary, the areas known to receive major pollution loads from neighbouring sources. Heavy metals found in the sediments were compared to previous studies. Bottom sediments and organisms surrounding major discharge points showed higher concentrations of pollutants and compared to previous studies, these concentrations seem to be increasing. Due to biomagnification, higher concentrations were generally found in the top predators although certain elements did not show this trend. Some heavy metal concentrations found in the fish exceeded of the food guidelines and may in turn pose a threat for subsistence users of the SRE. There are indications of multiple different pollution sources. Bird eggs had detectable quantities of polychlorinated biphenyls, but its implications need more investigation. / MSc (Zoology), North-West University, Potchefstroom Campus, 2014

Estuaries are among the most productive and diverse of aquatic habitats supporting a rich variety of plants and animals. They are nursery areas for many species of fish harvested by recreational and subsistence anglers. The Swartkops River Estuary (SRE) is situated approximately 10 km north-east of Port Elizabeth and the only major well-preserved estuary within a city, thus unique to South Africa. The SRE is surrounded by highly urbanized and industrialized regions in the Eastern Cape. The aim of this study was to determine and interpret the presence, levels, and distribution of selected priority pollutants in the food web of the SRE. Different components within the SRE were analysed for the presence of environmental contaminants. Seven sites were selected, some coinciding with previous studies in the SRE. Three of these sites are major discharge points that discharge directly into the estuary. Sediment, mud prawn, sand gobies, bird eggs, and various fish species were analysed. Samples were collected in the middle and lower reaches of the estuary, the areas known to receive major pollution loads from neighbouring sources. Heavy metals found in the sediments were compared to previous studies. Bottom sediments and organisms surrounding major discharge points showed higher concentrations of pollutants and compared to previous studies, these concentrations seem to be increasing. Due to biomagnification, higher concentrations were generally found in the top predators although certain elements did not show this trend. Some heavy metal concentrations found in the fish exceeded of the food guidelines and may in turn pose a threat for subsistence users of the SRE. There are indications of multiple different pollution sources. Bird eggs had detectable quantities of polychlorinated biphenyls, but its implications need more investigation. / MSc (Zoology), North-West University, Potchefstroom Campus, 2014

Multiscale (analytical and computational) models have been developed based on a thermodynamic variational principle (TVP) to model sintering and eventual mudcracking in thermal barrier coatings (TBCs) made using the electron beam physical vapour deposition (EB-PVD) process. It is assumed that the sintering occurs by interfacial diffusion at local contacts between columns and driven by changes in interface free energy and elastic stored energy of the coating. The models link diffusional processes at the scale of contacting feathery columns with the macroscopic deformation and sintering response. In service, the columns can come into contact and sinter together. As sintering progresses there is a build up of strain energy in the system which reduces the driving force for sintering and leads to either complete or incomplete sintering of the TBC depending on the magnitude of effective modulus (E) of the coating. By seeding the coating with initial imperfections, different types of behaviour are observed depending on the value of E and the spacing between imperfections. For compliant coatings, the response is insensitive to the presence of imperfections and the coating fully sinters. At higher values of E, strain energy is released by the development of intercolumnar cracks in the coating, which can propagate to the interface with the TGO (thermally grown oxide), deflect into the interface and propagate, leading to spallation of regions of the coating and loss of thermal protection. It is observed that cracks develop at initial imperfections in the structure. The greater the spacing between imperfections the faster the development of cracks at these locations. If a TBC contains a distribution of imperfections there is progressive formation of cracks, with the average spacing decreasing with time, after an initial incubation period. The crack density eventually saturates to a constant value, which depends on the mechanical properties of the TBC. Initially, a crack spacing, CS, in the range 1.5H ≤ CS ≤ 3H has been predicted based on trapezoidal contact models. Here H is the thickness of the coating. Crack spacing predicted using this model is consistent in the lower range of experimentally observed crack spacing. However, axisymmetric contact models predict a crack spacing, CS, in the range 4H ≤ CS ≤ 8H, which is in good agreement with experimentally observed crack spacing range 3H ≤ CS ≤ 10H reported in the literature. Compared to the trapezoidal contact models, axisymmetric contact models more accurately predict the sintering response.

The central objective of the study was to fractionate sedimenting organic materials according to their source (allochthonous or autochthonous) and ultimately to determine the degree of biodegradability of contributions from either source with particular reference to activities at the mud-water interface.

Orientador: Fabiano Tomazini da Conceição / Banca: Maria Lucia Pereira Antunes / Banca: Carlos Alfredo Suárez / Resumo: Este estudo teve como objetivo caracterizar as propriedades da lama vermelha brasileira natural, tratada termicamente a 400ºC e tratada quimicamente por ácido clorídrico (HCI) e nitrato de cálcio (Ca(NO3)2), e avaliar a sua capacidade de adsorção de níquel (Nr2+) e zinco (Zn2+) em soluções aquosas. A influência da variação do pH no processo de adsorção foi analisada, encontrando-se o pH 7, dentre os valores estudados, como o ideal para a adsorção. Também foram realizados testes de adsorção com variação da concentração inicial de Nr2+ e Zn2+, em pH 5-5,5; a partir dos quais foram elaboradas isotermas de adsorção ajustadas pelos modelos de Freundlich e Langmuir. Como resultado, percebeu-se que a lama vermelha é um adsorvente efetivo de Nr2+ e Zn2+, sendo a lama ativada termicamente a que apresentou maior capacidade de adsorção para ambos os metais, tendo sido encontrados os valores de 1,86 mmol/g para o Nr2+ e 1,43 mmol/g para o Zn2+. Além disso, o tempo de equlíbrio de sete horas foi encontrado e a cinética da reação foi estudada por meio dos modelos de pseudo-primeira ordem, pseudo-segunda ordem, Elovich e difusão intrapartículas, em pH 5-5,5. Concluiu-se que a reação de adsorção seguiu o modelo sde pseudo-segunda ordem. Também foram realizados estudos de termodinâmica, em pH 5-5,5, indicando que a reação de adsorção é endotérmica e que os metais possuem afinidade com a lma vermelha. Sendo assim, pode-se concluir que a lama vermelha tem potencial para ser utilizada como um adsorvente de baixo custo de aquisição para o tratamento de efluentes contaminados por metais / Abstract: This study aimed to characterize the properties of natural Brazilian red mud, heat treated red mud at 400ºC and chemically treated red mud by hydrochloric acid (HCI) and calcium nitrate (Ca(NO3)2), and evaluate its adsorption capacity for nickel (Nr2+) and zinc (Zn2+) in aqueous. Influence of pH variation in adsorption process was analyzed, finding pH 7, among studied values, as the ideal for adsorption. Also adsorption tests varying Nr2+ and Zn2+ initial concentrations were performed, at pH 5-5,5, and adsorption isotherms adjusted by Freundlich and Langmuir models were prepared. As a result, red mud was considered an effective Nr2+ and Zn2+ adsorbent. The thermally activated red mud showed the highest adsorption capacity for both metals, presenting maximum adsorption values of 1.86 mmol/g for Nr2+ and 1.43 mmol/g for Zn2+. Furthermore, the equilibration time of seven hours was found and pseudo -first order, pseudo-second order, Elovich and intraparticle diffusion models were used to study the kinetics, at pH 5-5,5. The results showed reaction of adsorption followed the pseudo-second order model. Also thermodynamic studies, at pH 5-5,5, were conducted, which indicated adsorption reaction is endothermic and the metals have affinity to red mud. Thus, it was concluded that red mud has potential to be used as an adsorbent of low acquisition cost for treatment of effluents contaminated by metals / Mestre

Orientador: Maria Lúcia Pereira Antunes / Banca: Marcio Alexandre Marques / Banca: José Lázaro Ferraz / Resumo: A geração de resíduos de mineração, sempre foi considerada um potencial risco ao meio ambiente, sendo de suma importância encontrar soluções alternativas de aproveitamento e valorização dos mesmos, com o objetivo de minimizar a disponibilidade no meio ambiente e atribuir novas funções para este tipo de material. O Brasil é um grande produtor de bauxita, sendo classificado entre os primeiros produtores desse mineral no mundo, porém o seu processamento gera um resíduo bastante alcalino denominado lama vermelha. Neste trabalho, foram determinadas propriedades físicas e químicas da lama vermelha total e de sua fração areia, obtida por peneiramento. Para isso foram feitas análises por Microscopia Eletrônica de Varredura (MEV), Espectroscopia de Dispersão de Energia (EDS), Fluorescência de Raios-X (FRX) e massa específica pela técnica de picnometria. Através desses resultados pode-se concluir que é possível através de uma técnica simples, segregar diferentes composições químicas elementares desse resíduo, como Si, Fe, Na e Ca. Atrelados à separação granulométrica, os resultados de massa específica mostram que a fração areia é mais densa e destaca-se também que cerca de 96% da massa da lama vermelha aqui estudada encontra-se nessa fração granulométrica. Também foi possível verificar a viabilidade de se utilizar esse resíduo e sua fração areia para produzir revestimentos em ligas de alumínio 1200, através de oxidação eletrolítica assistida por plasma (PEO). Dependendo das condições d... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: The generation of mining waste has always been conducted as a potential risk to the environment, and the amount of residual resources is the option of utilization and valorization, with the aim of minimizing the environment and new functions for this type of material. Brazil is a major producer of bauxite, being classified among the first producers of this mineral in the world, but its processing generates a rather alkaline residue called red mud. In this work, the physical and chemical properties of the total red mud and its sand fraction obtained by sieving were determined. For this, analyzes were performed by Scanning Electron Microscopy (SEM), Energy Dispersion Spectroscopy (EDS), X-Ray Fluorescence (FRX) and specific mass by the technique of pycnometry. Through these results it can be concluded that it is possible through a simple technique to segregate different elementary chemical compositions of this residue, such as Si, Fe, Na and Ca. The results show that the sand fraction is denser and that 96% of the mass of the red mud studied here is in this granulometric fraction. In this work, it was also possible to verify the viability of using this residue and its sand fraction to produce coatings in aluminum alloys 1200, through plasma assisted electrolytic oxidation (PEO). Depending on the deposition conditions, such as concentration (5g/ L and 10 g/L) and deposition time (300, 600 and 900 seconds), the coatings provide different physical and chemical characteristics and ... (Complete abstract click electronic access below) / Mestre

[pt] O atual modelo de desenvolvimento das cidades, juntamente com o consumo desenfreado dos recursos não renováveis, mostrou-se inviável do ponto de vista da sustentabilidade, fato este que tem gerado preocupação em diversos setores da sociedade. No cenário mundial, principalmente no setor da construção civil, vem crescendo a demanda pelo uso de novos materiais e técnicas que não sejam agressivos ao meio ambiente. O meio acadêmico, como ambiente de pesquisa é um dos locais para a geração desses novos materiais e técnicas que possam suprir as demandas visando o desenvolvimento sustentável. Nesse contexto, o LILD (Laboratório de Investigação em Living Design) vem estudando nos últimos 20 anos tecnologias limpas de baixo impacto ambiental, atendendo a demandas reais na construção de objetos de design e arquitetura. No momento o LILD trabalha, entre outras atividades, com materiais compósitos de terra crua e fibras naturais. Este trabalho apresenta o resultado do processo de desenvolvimento no LILD de um objeto feito com estes compósitos, denominado CÚPULA CATENÁRIA, com a aplicação da metodologia projetual utilizada no LILD. Os experimentos foram desenvolvidos a partir de modelos processuais que determinaram os parâmetros e apontaram as diretrizes a serem seguidas no projeto, visando sempre a aplicação e construção de um modelo em escala real, que por sua vez incorpora diversos saberes de diferentes áreas de conhecimento. / [en] The current model of cities development, considering the wild consumption of not renewable resources, has shown impracticable due the sustainability point of view. Fact which is really concerned a lot of preoccupation in many sectors of human society. In the world-wide scenery, mainly at civil construction sector, it is growing a big demand for the use of new and alternative materials and techniques that may not harm the world environment. Due this situation, in the academic field that is considered an excellent research environment, it is the right place to new materials and techniques born in order to supply the demands considering the sustainable development. In this context, the LILD (Research Living Design Laboratory) has been studying last 20 years the applications of clean and low environmental impact technologies, answering the demands of building the design and architecture of real objects. This work presents the result of the developing process of an object named CATENARY DOME, applying the project methodology of LILD. The experiments have been developed of processual models that determined the parameters and point directives to be followed in the project, having in mind always the application and construction of an object in real scale, that incorporate many different knowledge areas.

Red mud is a waste product of alumina production and has an adverse effect on environment. About 90 million tonnes of red mud are produced annually throughout the world and little is recycled for useful applications. The world nickel reserves consist of approximately 30% sulphide ores and 70% oxide ores. Despite the relative abundance of oxide ores, 55% of nickel and nickel alloys produced today are derived from sulphide ores. However, with the production of nickel and its alloys from low-grade oxide ores becoming increasingly important, a major concern is high sulphur level in the resultant alloy. For this reason, desulphurization of the ferronickel becomes an important consideration. In the present study, experiments were conducted to determine if red mud could be used as a major ingredient of custom designed fluxes for the desulphurization of ferronickel alloy. Factors investigated included desulphurization rates, contact angle measurements and flux-refractory interactions.

Red mud is a waste product of alumina production and has an adverse effect on environment. About 90 million tonnes of red mud are produced annually throughout the world and little is recycled for useful applications. The world nickel reserves consist of approximately 30% sulphide ores and 70% oxide ores. Despite the relative abundance of oxide ores, 55% of nickel and nickel alloys produced today are derived from sulphide ores. However, with the production of nickel and its alloys from low-grade oxide ores becoming increasingly important, a major concern is high sulphur level in the resultant alloy. For this reason, desulphurization of the ferronickel becomes an important consideration. In the present study, experiments were conducted to determine if red mud could be used as a major ingredient of custom designed fluxes for the desulphurization of ferronickel alloy. Factors investigated included desulphurization rates, contact angle measurements and flux-refractory interactions.

In this thesis, we consider the uplink of a cooperative code division multiple access (CDMA) network, where users cooperate by relaying each other¡¦s messages to the base station. The sources adopt CDMA to share the informations offered by relays. In general, spreading waveforms of sources are not orthogonal to each others due to pratical design issues of CDMA network. Therefore, the source signals will suffer from multiple access interference (MAI) at the relays and destination. The MAI results in the increase of bit error rate increased, and diminishes the cooperative network diveristy gains. In order to mitigate MAI, the decorrelating multiuser detection and zero-forcing precoder have been commonly adopted. But, the decorrelating multiuser detection causes noise enhancement, while the zero-forcing precoder causes power expansion. In this thesis, we adopt relay-assisted decorrelating multiuser detector (RAD-MUD) to mitigate MAI as proposed in [1].In this scheme, the relays perform half of decorrelating operation and the destination performs the other half. In this way, neither noise enhancement nor power expansion will occur. However, in the reference [1], the authers assume the transmission is synchronous between sources and relays. The assumption is unrealistic, because it is difficult to achieve synchronization between all sources and relays due to various propagation delays. In this thesis, we extend the research in [1] and relax restriction of synchronization between all sources and relays. Besides, we also adopt cooperative strategies such as transmit beamforming or selective relaying to enhance system performance. Compared with other¡¦s multiuser detection schemes, we show that the proposed schemes can effectively reduce the bit error rate.