O processo de flotação por ar dissolvido antecedendo a filtração, constitui hoje técnica já consolidada para clarificação de água para abastecimento. Apesar de apresentar elevada eficiência de remoção de partículas em suspensão e das diversas vantagens associadas a sua utilização, ainda existem particularidades deste processo pouco conhecidas. Visando compreender melhor a flotação por ar dissolvido e contribuir para a otimização das unidades existentes e também nos projetos de novas unidades, foram utilizadas técnicas de fluidodinâmica computacional para estudar as condições de escoamento entre água e ar observadas numa unidade piloto de flotação. A flotação foi investigada através de simulações em ambiente de CFD, acoplado a experimentos laboratoriais em instalação piloto de flotação por ar dissolvido. Estes últimos compreenderam a execução de ensaios com traçador para obtenção das curvas de distribuição de tempo de residência na unidade em questão e também por testes com sonda do tipo Micro ADV para levantamento do perfil de velocidades de escoamento no interior da unidade piloto. Os resultados das análises experimentais com sonda Micro ADV indicaram a presença de escoamento estratificado na região superior da zona de separação da unidade piloto. As curvas de distribuição do tempo de residência apontaram para escoamento do tipo pistonado. O tempo de detenção observado nos ensaios foi de 19,29 e 18,66 minutos respectivamente para escoamento somente de água e sem recirculação e escoamento entre água e ar. As simulações em CFD confirmaram a presença de escoamento estratificado na zona de separação e também a presença de uma manta de microbolhas de ar na mesma. Os resultados foram sensíveis ao diâmetro de microbolhas testado, com maior concentração de ar na zona de separação quando testados diâmetros de microbolhas menores que 60 µm. As curvas de distribuição de tempo de residência obtidas nas simulações em CFD foram capazes de representar o escoamento entre água e ar. O tempo de detenção hidráulico simulado foi de 14,24 e 18,90 minutos respectivamente para as mesmas condições experimentais testadas. De uma maneira geral, as simulações em CFD foram capazes de reproduzir as condições de escoamento entre ar e água observadas na unidade piloto de flotação, os resultados computacionais são condizentes com aqueles obtidos nos ensaios experimentais. / The dissolved air flotation process preceding filtration, consist in established technique for clarification of water supply. Despite presenting high suspended particle removal efficiency and the various advantages associated with their use, there are still a few particularities of this process slightly unknown. To better understand the dissolved air flotation and contribute to the optimization of the existing units and also in projects of new units, computational fluid dynamics techniques were used to study the flow conditions between water and air observed in a flotation pilot plant. The flotation process was investigated in CFD environment, coupled to laboratory experiments in dissolved air flotation scale pilot plant. The latter comprised running tests with tracer to obtain the residence time distribution curves in the pilot plant, tests with micro ADV probe were also conducted for raising the flow velocity profile within the unit. The results of micro ADV experimental analyzes indicated the presence of stratified flow in the upper region of the separation zone of the pilot plant. The residence time distribution curves pointed to plug flow. The retention time observed in the experiments were 19,29 and 18,66 minutes, respectively for the flow of water only and without recirculation and flow of water and air. The CFD simulations confirmed the presence of stratified flow in the separation zone and also the presence of a microbubble air blanket therein. The results were sensitive to the diameter of microbubbles tested, with bigger air concentration in the separation zone when tested with microbubbles diameters smaller than 60 micrometers. The residence time distribution curves obtained in CFD simulations were able to represent the water and air flow. The simulated hydraulic retention times obtained were 14,24 and 18,90 minutes, respectively, for the same experimental conditions. In general, the CFD simulations were able to reproduce the flow conditions observed between air and water in the flotation pilot plant, the computational results were consistent to those obtained in the experiments.

The basic understanding of mixing in the process of polymer melt extrusion by twin screw extruder is limited by their geometrical complexity and the interactions of the process parameters. Mixing and flow in a 100mm diameter, trapezoidal channeled, intermeshing co-rotating twin-screw extruder have been characterised by determination of residence time distribution (RTD) and of the paths taken by tracers added to the melt. The axial mixing and the effects of varius parameters on it were established by studying RTD using tracer techniques. As the tail of the distribution is of paramount importance, the reproducibility of the RTD curve was extensively studied. Radioactive NnO2 was used as a tracer and detected by gamma ray spectroscopy giving more reproducible results than added barytes estimated gravimetrically after ashing. Shock cooling of the extruder and sectioning of the solidified compound in the screw channels was used to-study the flow mechanism. The maximum throughput achieved, polymer melting mechanism, filled volume and axial mixing Are interrelated, and are dependent on the configuration and position of segmented mixing discs present in the screw profile. In the upstream position these act as melting discs and their efficiency is increased in a closed configuration. Initial melting is achieved over a remarkably short distance along the screw profile. The screw speed affects the axial mixing which is shown to be related to the net relative pressure change at the screw tips. A flow model is proposed such that the overall material flow taking place in an anticlockwise direction along the screw channel comprises two separate flow regimes. The upper regime rotates anti-clockwise and is made up of main and small tetrahedron flow and calender flow. The lower flow regime rotates clockwise and is made up of main and small side leakage flows and a portion of the main tetrahedron flows together with a central flow. The flow studies show conclusively that the melt from a particular site ahead of the intermeshing zone occupies a predestined site after passing through the intermeshing zone.

The point of departure of this dissertation is that notwithstanding the controversy about the right to development (RTD), the African human rights system expressly recognises it as a human right of a collective nature. The content of this right is a bundle of rights (civil and political as well as economic, social and cultural) which should be understood in their interdependency and interconnectedness. In addition, the RTD is a claim for a global justice characterized by a fair and equitable redistribution of the world’s resources. The purpose of this dissertation is to critically investigate the extent to which the RTD can be realised under the New Partnership for Africa’s Development (NEPAD). NEPAD is the economic and development arm of the African Union which is compelled by its human rights mandate to ‘promote and protect human and peoples’ rights in accordance with the African Charter on Human and Peoples’ Rights including the RTD. The dissertation looks at how NEPAD could be used to realise the RTD in Africa. After clarifying the theoretical and contextual links between NEPAD and the RTD, explaining the concepts pertaining to RTD, its nature and after locating its existence in the African human rights system, the dissertation examines the prospects for the realisation of this right through NEPAD. In doing so, it analyses NEPAD from a human rights perspective. It then goes on to look at the extent to which NEPAD’s programmes on vulnerable groups and participation, are integrated into national development policies in Africa through case studies of Cameroon and South Africa. The dissertation also examines whether the new global partnership as prescribed by NEPAD is conducive to the realisation of the RTD. The basic conclusion is that although NEPAD’s plan to foster the provision of goods and services is not defined in terms of legal entitlements, with legal mechanisms to claim such entitlements, NEPAD’s objectives and purposes are to improve human welfare, which is also the objective of the RTD. However, to enhance the prospects for the achievement of the RTD in Africa, NEPAD should establish and strengthen mechanisms for a full domestication and ownership of its plans and standards in African states. It should also strengthen the African Peer Review Mechanism (APRM) institutions at both continental and national levels. Further, it should involve the African Commission on Human and Peoples’ Rights, which has expertise in human rights, in its APRM. At the global level, among others, NEPAD should not only strive to be economically self-reliant, but its member states should speak with ‘one voice’ and present the African Union/NEPAD’s position at international fora and consistently ensure that Africa’s development contracts and agreements are informed by international human rights standards. / Thesis (LLD)--University of Pretoria, 2012. / Centre for Human Rights / unrestricted

Cette étude concerne l'optimisation, la conception et la caractérisation de microréacteurs, de type multicanaux, appliqués à l'électrosynthèse organique de composés fluorés à intérêt médical tels que le 2-Fluoro- 2-Deoxy-D-Glucose (18FDG). Les microsystèmes ont connu un développement important ces dernières années dans le domaine de la chimie fine où la volonté est de développer des outils toujours plus compétitifs. Les microréacteurs appliqués à la synthèse offrent l’avantage d’un rapport surface sur volume de la zone réactionnelle élevé (> 100 cm-1), ce qui améliore nettement les transferts de masse et d’énergie et permet de traiter de très faibles quantités dans des conditions plus sûres et plus respectueuses de l’environnement. L’élément de base du microréacteur est souvent constitué d’un simple microcanal qu’il est nécessaire de dupliquer pour fournir le débit de production adapté à une application donnée. Ainsi, un microréacteur sera souvent composé d’une série de microcanaux disposés en parallèle et connectant un canal distributeur et un canal collecteur. Cette configuration peut entraîner une faible uniformité de la distribution de l’écoulement dans les différents microcanaux de réaction et il est particulièrement important d’optimiser la géométrie du microréacteur complet pour tendre vers une distribution uniforme des temps de séjour (DTS). Dans le cas de la synthèse électrochimique, les microcanaux sont directement gravés dans deux électrodes placées en vis-à-vis et séparées par une membrane échangeuse d’ions. Une optimisation préliminaire de la DTS au sein d’une électrode composée de microcanaux parallèles de section rectangulaire est réalisée. L’arrivée et la sortie du fluide s’effectue par l’intermédiaire de deux canaux distributeur et collecteur de section également rectangulaire, mais non constante. L’optimisation vise à déterminer une évolution linéaire optimale de la largeur de ces canaux distributeur et collecteur. Un modèle analytique basé sur des hypothèses simplificatrices permet de calculer les différentes pertes de charge ainsi que les débits dans chaque microcanal, dans le cas d’un écoulement laminaire de liquide. Les résultats obtenus sont ensuite confirmés par des simulations numériques 3-D, plus précises. Un modèle hybride combinant les simulations numériques pour les canaux distributeur et collecteur et le modèle analytique pour les microcanaux parallèles est également développé. Il permet d’augmenter la finesse du maillage dans les zones sensibles de l’écoulement, sans nécessité d’accroître les ressources informatiques (mémoire et temps de simulation). Les résultats obtenus montrent un très bon accord entre les simulations numériques 3-D, le modèle hybride et le modèle analytique. Sur un exemple de 10 microcanaux parallèles, il est montré que dans le cas de la géométrie initiale, pour laquelle les canaux collecteur et distributeur sont de section constante, des écarts de l’ordre de 50 % existent entre les débits traversant les microcanaux latéraux et centraux. Après optimisation, cet écart est réduit à moins de 0,1 %. Le modèle analytique est ensuite étendu au cas d’écoulements gazeux en prenant en compte les effets non linéaires et antagonistes de la raréfaction et de la compressibilité de l’écoulement. La raréfaction est ici caractérisée par un nombre de Knudsen compris entre 0 et 0,1 et se traduit pas des sauts de vitesse à la paroi ; les écoulements dans ce régime modérément raréfié sont alors correctement modélisés par les équations compressibles de Navier Stokes associées à des conditions de glissement du second ordre en Knudsen, en prenant en compte la géométrie tridimensionnelle des microcanaux de réaction et des canaux collecteur et distributeur. / This study focuses on the optimisation, design and characterization of microreactors, of multichannel type, applied to the organic electrosyntheses of fluorinated compounds of medical interest such as the 2-Fluoro-2-Deoxy-D-Glucose (18FDG). Microsystems have known an important development these last years in the field of fine chemicals where the aim is to develop increasingly competitive tools. The microreactors applied to synthesis offer a reaction zone with high surface to volume ratio (> 100 cm-1), which significantly improves mass and energy transfers and allows treating small quantities in safer conditions and a better respect of environment. The basic element of the microreactor is often composed of a single microchannel, which is necessary to duplicate in order to provide the suitable production rate for a given application. Thus, a microreactor is often composed of a series of microchannels arranged in parallel and connecting a distributing channel to a collecting one. This configuration can result in poor uniformity of flow distribution among the reaction microchannels and it is particularly important to optimize the geometry of the microreactor in order to obtain a uniform residence time distribution (RTD). In the case of electrochemical synthesis, microchannels are directly etched into two electrodes facing each other and separated by an ion exchange membrane. A preliminary optimisation of the RTD in an electrode composed of parallel microchannels with rectangular cross-section is performed. The fluid inlet and outlet are connected to a distributing and a collecting channel with non constant rectangular cross-section. The aim of the optimisation is to determine an optimal linear evolution of the width of the distributing and collecting channels. An analytical model based on simplifying assumptions allows calculating the various pressure drops and the flowrate in each microchannel, in the case of a laminar liquid flow. The obtained results are then confirmed by more accurate 3-D numerical simulations. A hybrid model combining numerical simulations for the distributing and collecting channels and the analytical model for the parallel microchannels is also developed. This model allows a more refined mesh in the sensitive areas of the flow, without requiring additional numerical effort (memory and simulation time). The results show a good agreement between the 3-D numerical simulations, the hybrid model and the analytical model. On an example of 10 parallel microchannels, it is shown that in the case of the initial geometry (with a constant cross-section of collecting and distributing channels), the flowrate difference through the lateral and the central microchannels is in the order of 50%. After optimization, this difference is reduced to less than 0.1%. The analytical model is then extended to the case of gas flows, taking into account nonlinear and antagonist effects of rarefaction and compressibility. Rarefaction is characterized by the value of the Knudsen number which remains lower than 0.1; the flow in this moderately rarefied regime is accurately modelled by the compressible Navier-Stokes equations associated with second-order slip boundary conditions, taking into account the three-dimensional geometry of the reaction microchannels and of the collecting and distributing channels.

This work deals with hardware and software solution for the temperature converter of the standard rezistance temperature Ni sensors with the output through the Ethernet, driven by the Rabbit microcontroller. First part of this thesis deals with the theory of the temperature measurement. There are introduced basic principles of the temperature sensors. In the next part of the work are introduced communication standard and application protocol Modbus. The rest of the work deals with the hardware concept of the converter, the control program of the converter and the program developed for the PC.

Discusses the human rights obligations of International Financial Institutions and suggests different human rights accountability mechanisms through the Right to Development paradigm / Thesis (LLM (Human Rights and Democratisation in Africa)) -- University of Pretoria, 2008. / A Dissertation submitted to the Faculty of Law University of Pretoria, in partial fulfilment of the requirements for the degree Masters of Law (LLM in Human Rights and Democratisation in Africa). Prepared under the supervision of Prof. Jaap de Visser, Faculty of Law, University of Western Cape, South Africa / http://www.chr.up.ac.za/ / Centre for Human Rights / LLM

Arbetet har genomförts på uppdrag av Katastrofmedicinskt Centrum. Syftet var att utforska vilka möjligheter det finns med digitala simuleringsverktyg för stötta kollaborativt lärande och testande av hälso- och sjukvårdsorganisationers katastrofmedicinska sjukvårdsledningsförmåga. Utgångspunkten har varit dagens analoga simuleringsverktyg. Katastrofmedicinska händelser förekommer sällan vilket skapar behovet att kunna återskapa och öva på dessa, tidigare studier har visat på brister sjukvårdsledning i vårdkedjan som minskat patientsäkerheten. Forskningsansatsen var forskning-genom-design (Research through Design, RtD). Designutforskningen resulterade i fyra olika designkoncept, assisterande faciliteringsverktyg, ökade kontrollmöjligheter, enkel interaktion, och ökade träningsmöjligheter. Designkoncepten stärker samarbetet mellan deltagarna och ökar tiden spenderad på att utföra aktiviteter på sjukvårdsledningsnivå samt hjälper facilitatorer att planera och genomföra nya typer av övningar. Designprocessen visade också att digitala simuleringsverktyg bör ses som kompletterande istället för ersättare av analoga verktyg då det analoga materialet har andra styrkor. På så sätt kan styrkorna med digitala verktyg användas till fullo.

On the way to develop a complete full-band quantum transport simulation using the Pauli Master Equation, we show our present results on 1D n-i-n resistors, 1D double barrier resonant tunneling diodes (DBRTD), and 2D double-gate field effect transistors (DGFETs) using a simplified parabolic, spherical effective-mass band-structure model accounting for nonpolar scattering with acoustic (elastic) and optical (inelastic) silicon-like phonons. We also consider the effect of point-like dopants on the access resistance of thin-body double gate devices.

Anaerobic digestion is one of the most promising management options for dairy manure treatment. Manure wastewater from dairy farms has been used for methane production for decades. However, performance failure due to inadequate mixing is routine. In general, the mixng of anaerobic digester is achived throguh mechnical stirring, liquid circulation, and gas circulation, among which the gas circulation proves to be the most effcient way. In this work, we studied the liquid flow pattern of two differetn type of gas-circualtion based anaerobic digesters, with the aim to understand the effects of hydrodynamic behavior of the digesting liquid on the anaerobic digestion performance, so a better mixing strategy can be provided. We used two 20-L gas circulation based anaerobic digesters with confined (gas-lift) and unconfined (bubble column) design. The anaerobic digestion performance and mixing behaviors were studied at different gas recirculation rate. It was found that the biogas production from the bubble column was constantly higher than that from gas-lift digester. However, the overall flow of the two digesters, which is indicated by residence time distribution (RTD), showed a similar pattern. Furhter investigation of local liquid flow behavior using Computational Fluid Dynamic (CFD) indicate that the bubble column accumulated higher portion of sludge in the bottom of the digester, which has a higher TS and VS, COD, and biomethane production potential than those from the gas-lift digester. This is the reason that the biogas production from the bubble column is higher than the gas-lift digester. Through this study, a thorough characterization of the flow behavior of the anaerobic digester were developed, and provided a deep insight of its influence on the anaerobic digestion performance. / Master of Science

Toward the objective to create or to replace impaired tissues, it is essential to establish a culture process allowing tissue growth in vitro . The Petri dish culture or the traditional 2D culture has only a limited potential, mainly caused by a poor oxygen mass transfer to feed larger tissue constructs. In this project, an autonomous and complete bioprocess has been built to fullfill these needs. The developed reactor is versatile because many cell culture chamber designs can be connected to it. Two proportional-integral algorithms (PI) can control the dissolved oxygen concentration and the pH. The pressure, the temperature and mass flow rate are recorded in real time. An actuator allows mimicking the cardiac output flow. In this mémoire , it will be demonstrated how the reactor has been optimized to reduce the risk of bioburden. Also, the procedures to develop the control tools of the PI algorithm will be detailed. To characterize the reactor, a RTD study will be presented. To characterize the cell culture chamber, a permeability analysis using fluorescent microscopy and magnetic resonance imaging (MRI) will be exposed. Finally, two cell culture chamber designs to orient microvessel formation have been tested and these results will be presented.