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The purpose of this work was to understand the influence of materials and construction on football performance. Two main areas identified as needing further work were post-impact rebound deviation and acoustic response. To further investigate these areas, football materials were tested in a lab with different loading scenarios and the resulting data was used in various characterisation methods to help define finite element models. The finite element models were used to efficiently explore a variety of material and construction variations. Acoustic data for a range of balls was collected in an anechoic chamber and advanced coupled Eulerian-Lagrangian simulations were developed to visualise the mode shapes of internal resonances.

In der Reaktorsicherheitsforschung sind auftriebsgetriebene Strömungen von Relevanz für Störfall-szenarien mit Verdünnung der Borkonzentration und für thermische Schockbelastungen des Reak-tordruckbehälters. In der numerischen Simulation der Strömungen werden neben der Berücksichtigung der Auftriebskräfte Quell- und Korrekturterme in die Bilanzgleichungen für die turbulente Energie und die turbulente Dissipation eingeführt. Es wurden erweiterte Modelle entwickelt, in die zusätzliche Gleichungen für die Turbulenzgrößen turbulenter Massenstrom und Dichtevarianz eingehen. Die Modelle wurden in den CFD-Code ANSYS-CFX implementiert. Die Validierung der Modelle erfolgte an einem speziellen Versuchsaufbau (VeMix-Versuchsanlage), mit Einspeisung von Fluid höherer Dichte in eine Vorlage. Als Kriterien für die Validierung wurde der Umschlag zwischen impulsdominiertem Strömungsregime mit vertikalem Jet oder ein vertikales Absinken bei Dominanz von Dichteeffekten herangezogen sowie lokale Konzentrationsmessungen mit Hilfe eines speziell entwickelten Leitfähigkeits-Gittersensors. Eine Verbesserung der Simulation dichtedominierter Vermischungsprozesse mit den erweiterten Turbulenzmodellen konnte allerdings nicht nachgewiesen werden, da die Unterschiede zwischen den Rechnungen mit verschiedenen Turbulenzmodellen zu gering sind. Andererseits konnte jedoch die Simulation der Stratifikation von Fluiden unterschiedlicher Dichte im kalten Strang einer Reaktoranlage deutlich verbessert werden. Anhand der Nachrechnung von Ver-suchen am geometrisch ähnlichen Reaktor-Strömungsmodell ROCOM wurde gezeigt, dass diese Stratifikation von bedeutendem Einfluss auf die Vermischung und somit letztendlich auch auf die Temperatur- bzw. Borkonzentrationsverteilung innerhalb des Reaktordruckbehälters ist. Sie lässt sich nur korrekt simulieren, wenn ausreichend große Abschnitte des kalten Stranges mit modelliert werden. Somit konnte doch eine bessere Vorhersagegenauigkeit der Simulation der Vermischung erreicht werden. In reactor safety research, buoyancy driven flows are of relevance for boron dilution accidents or pressurised thermal shock scenarios. Concerning the numerical simulation of these flows, besides of the consideration of buoyancy forces, source and correction terms are introduced into the balance equations for the turbulent energy and its dissipation rate. Within the project, extended turbulence models have been developed by introducing additional balance equations for the turbulent quantities turbulent mass flow and density variance. The models have been implemented into the computati-onal fluid dynamics code ANSYS-CFX. The validation of the models was performed against tests at a special experimental set-up, the VeMix facility, were fluid of higher density was injected into a vertical test section filled with lighter fluid. As validation criteria the switching-over between a momentum controlled mixing pattern with a horizontal jet and buoyancy driven mixing with vertical sinking down of the heavier fluid was used. Additionally, measurement data gained from an especially developed conductivity wire mesh sensor were used. However, an improvement of the modelling of buoyancy driven mixing by use of the extended models could not be shown, because the differences between calculations with the different models were not relevant. On the other hand, the modelling of the stratification of fluids with different density in the cold leg of a reactor primary circuit could be significantly improved. It has been shown on calculations of experi-ments at the ROCOM mixing test facility, a scaled model of a real reactor plant, that this stratification is relevant as a boundary condition for the mixing process inside the reactor pressure vessel. It can be correctly simulated only if sufficient large parts of the cold legs are included in the modelling. On this way, an improvement of the accuracy of the prediction of mixing processes was achieved.

By September 2009 the International Atomic Energy Agency reported that the number of commercially operated nuclear reactors in 30 countries across the world is 436, around 50 reactors are currently being constructed, 137 reactors have been ordered or is already planned, and there are around 295 proposed reactors. Pressurised water reactors (PWRs) make up the majority of these numbers. The growing number of carbon emissions and the ongoing fight against fossil fuel power stations might see the number of planned nuclear reactors increase even more to be able to satisfy the world’s need for cleaner energy. To ensure that technology keeps pace with this growing demand, ongoing research is essential. Not only is the research of new reactor technologies (i.e. High Temperature Reactors) important, but improving the current technologies (i.e. PWRs) is critical. With the increased contribution of nuclear generated electricity to our grids, it is becoming more common for nuclear reactors to be operated as load following units, and not base load units as they are more commonly being operated. Therefore a need exists to study and develop new strategies and technologies to improve the automatic load following capabilities of reactors. PWR power plants are multivariable systems. In this study a multivariable, more specifically, a model predictive controller (MPC) is developed for controlling the load following of a nuclear power plant, more specifically a PWR plant. In developing this controller system identification is employed to develop a model of the PWR plant. For the identification of the model, measured data from a computer based PWR simulator is used as the input. The identified plant model is used to develop the MPC controller. The controller is developed and tested on the plant model. The MPC controller is also evaluated against another set of measured data from the simulator. To compare the performance of the MPC controller to that of the conventional controller the ITAE performance index is employed. During the process Matlab ® , the System Identification Toolbox™, the MPC Toolbox™ and Simulink ® are used. The results reveal that MPC is practicable to be used in the control of non-linear systems such as PWR plants. The MPC controller showed good results for controlling the system and also outperformed the conventional controllers. A further result from the dissertation is that system identification can successfully be used to develop models for use in model based controllers like MPC controllers. The results of the research show that a need exists for future research to improve the methods to eventually have a controller that can be applied on a commercial plant. / Thesis (M.Ing. (Nuclear Engineering))--North-West University, Potchefstroom Campus, 2010.

By September 2009 the International Atomic Energy Agency reported that the number of commercially operated nuclear reactors in 30 countries across the world is 436, around 50 reactors are currently being constructed, 137 reactors have been ordered or is already planned, and there are around 295 proposed reactors. Pressurised water reactors (PWRs) make up the majority of these numbers. The growing number of carbon emissions and the ongoing fight against fossil fuel power stations might see the number of planned nuclear reactors increase even more to be able to satisfy the world’s need for cleaner energy. To ensure that technology keeps pace with this growing demand, ongoing research is essential. Not only is the research of new reactor technologies (i.e. High Temperature Reactors) important, but improving the current technologies (i.e. PWRs) is critical. With the increased contribution of nuclear generated electricity to our grids, it is becoming more common for nuclear reactors to be operated as load following units, and not base load units as they are more commonly being operated. Therefore a need exists to study and develop new strategies and technologies to improve the automatic load following capabilities of reactors. PWR power plants are multivariable systems. In this study a multivariable, more specifically, a model predictive controller (MPC) is developed for controlling the load following of a nuclear power plant, more specifically a PWR plant. In developing this controller system identification is employed to develop a model of the PWR plant. For the identification of the model, measured data from a computer based PWR simulator is used as the input. The identified plant model is used to develop the MPC controller. The controller is developed and tested on the plant model. The MPC controller is also evaluated against another set of measured data from the simulator. To compare the performance of the MPC controller to that of the conventional controller the ITAE performance index is employed. During the process Matlab ® , the System Identification Toolbox™, the MPC Toolbox™ and Simulink ® are used. The results reveal that MPC is practicable to be used in the control of non-linear systems such as PWR plants. The MPC controller showed good results for controlling the system and also outperformed the conventional controllers. A further result from the dissertation is that system identification can successfully be used to develop models for use in model based controllers like MPC controllers. The results of the research show that a need exists for future research to improve the methods to eventually have a controller that can be applied on a commercial plant. / Thesis (M.Ing. (Nuclear Engineering))--North-West University, Potchefstroom Campus, 2010.

Active Pharmaceutical Ingredients (APIs) are frequently prepared for delivery to the lung for local topical treatment of diseases such as Chronic Obstructive Pulmonary Disease (COPD) and asthma, or for systemic delivery. One of the most commonly used devices for this purpose is the pressurised metered dose inhaler (pMDI) whereby drugs are formulated in a volatile propellant held under pressure. The compound is aerosolised to a respirably sized dose on actuation, subsequently breathed in by the user. The use of hydrofluoroalkanes (HFAs) in pMDIs since the Montreal Protocol initiated a move away from chlorofluorocarbon (CFC) based devices has resulted in better performing products, with increased lung deposition and a concomitant reduction in oropharyngeal deposition. The physical properties of HFA propellants are however poorly understood and their capacity for solubilising inhaled pharmaceutical products (IPPs) and excipients used historically in CFCs differ significantly. There is therefore a drive to establish methodologies to study these systems in-situ and post actuation to adequately direct formulation strategies for the production of stable and efficacious suspension and solution based products. Characterisation methods have been applied to pMDI dosage systems to gain insight into solubility in HFAs and to determine forms of solid deposits after actuation. A novel quantitative nuclear magnetic resonance method to investigate the physical chemistry of IPPs in these preparations has formed the centrepiece to these studies, accessing solubility data in-situ and at pressure for the first time in HFA propellants. Variable temperature NMR has provided thermodynamic data through van’t Hoff approaches. The methods have been developed and validated using budesonide to provide limits of determination as low as 1 μg/mL and extended to 11 IPPs chosen to represent currently prescribed inhaled corticosteroids (ICS), β2-adrenoagonists and antimuscarinic bronchodilators, and have highlighted solubility variations between the classes of compounds with lipophilic ICSs showing the highest, and hydrophilic β2- agonist/antimuscarinics showing the lowest solubilities from the compounds under study. To determine solid forms on deposition, a series of methods are also described using modified impaction methods in combination with analytical approaches including spectroscopy (μ-Raman), X-ray diffraction, SEM, chromatography and thermal analysis. Their application has ascertained (i) physical form/morphology data on commercial pMDI formulations of the ICS beclomethasone dipropionate (QVAR®/Sanasthmax®, Chiesi) and (ii) distribution assessment in-vitro of ICS/β2-agonist compounds from combination pMDIs confirming co-deposition (Seretide®/Symbicort®, GlaxoSmithKline/AstraZeneca). In combination, these methods provide a platform for development of new formulations based on HFA propellants. The methods have been applied to a number of ‘real’ systems incorporating derivatised cyclodextrins and the co-solvent ethanol, and provide a basis for a comprehensive study of solubilisation of the ICS budesonide in HFA134a using two approaches: mixed solvents and complexation. These new systems provide a novel approach to deliver to the lung, with reduced aerodynamic particle size distribution (APSD) potentially accessing areas suitable for delivery to peripheral areas of the lung (ICS) or to promote systemic delivery.