Im Rahmen der Dissertation wurden Komplexe Intermetallische Phasen (KIP) in den Systemen Ag-Mg und Ag-Ga-Mg dargestellt und charakterisiert. KIP sind Verbindungen, die sich grundlegend von einfachen Metallen unterscheiden. Große Elementarzellen, ein hierarchisch strukturierter Aufbau und inhärente Fehlordnung sind wesentliche Charakteristika. Empirisch wird zudem eine Häufung von strukturchemisch verwandten KIP (Ähnlichkeitsregel) in der Nähe von definierten Zusammensetzungen beobachtet (Häufungsregel). Obwohl nur wenig über die physikalischen Eigenschaften dieser Verbindungsklasse bekannt ist, zeigen neueste Untersuchungen, dass sie interessante Eigenschaften wie ungewöhnliches plastisches Verhalten und Pseudo-Bandlücken in der elektronischen Zustandsdichte in Höhe der Fermi-Energie aufweisen können. Diese Arbeit zeigt exemplarisch, dass in der Chemie der KIP durchaus einfache Regeln (Häufungs-, Ähnlichkeits-, Valenzelektronenkonzentrationsregel) genutzt werden können, um neue Verbindungen mit vorgegebenen geometrischen Baueinheiten aufzufinden. Vereinfachende Annahmen, wie die Aussage, dass zweikomponentige Mackay-Cluster keine Fehlordnung aufweisen oder dass ein Mackay-Cluster maximal 92 Valenzelektronen enthält, erwiesen sich hingegen als falsch. Die Untersuchungen haben gezeigt, dass eine Kombination verschiedener Synthesemethoden notwendig ist. Insbesondere hat sich das Schmelzspinnverfahren, das zur Darstellung kristalliner magnesiumreicher Legierungen angewandt und modifiziert wurde, bei der phasenreinen Synthese der Verbindungen bewährt. Die Entwicklung von Spritzdüsen aus Tantal ermöglichte die kontaminationsfreie Verarbeitung der Mg-haltigen Legierungen. Die Bestimmung der Kristallstrukturen inklusive der Fehlordnungsphänomene war für das Verständnis der Stabilität der KIP entscheidend. Da häufig zwischen verschiedenen Modellen zur Beschreibung der Fehlordnung entschieden werden musste, waren neben präzisen Beugungsdaten genaue Untersuchungen der Präparate mittels chemischer Analytik, Metallographie und WDX hinsichtlich der Zusammensetzung aller Phasen erforderlich. Der magnesiumreiche Teil des binären Phasendiagramms Ag-Mg wurde neu bestimmt. Dabei wurden zwei bislang unbekannte Phasen dargestellt. Die fünf magnesiumreichen Phasen kristallisieren innerhalb eines schmalen Bereichs von nur 9 At.-% Mg. Die Kristallstrukturen dieser Phasen wurden unter besonderer Berücksichtigung der Fehlordnungsphänomene untersucht. Die Verbindungen sind strukturchemisch verwandt und lassen sich den I3-Cluster-Phasen zuordnen. Ag2Mg5 kristallisiert ohne Fehlordnung im Al5Co2-Typ. Die Kristallstrukturen von Ag7Mg26 und Ag17Mg54 lassen sich als fcc bzw. bcc Anordnungen von Mackay-Clustern beschreiben. Es handelt sich um die ersten bekannten binären Phasen, in denen innerhalb von isolierten Mackay-Clustern Substitutionsfehlordnung auftritt. AgMg4 kristallisiert hexagonal in einem eigenen Strukturtyp. Das I3-Cluster-Netzwerk füllt den gesamten Raum bis auf einen annähernd zylindrischen Bereich um 0, 0, z, in dem eine Atom-Split-Position aus drei Lagen vorliegt. Lokal liegen drei unterschiedliche Koordinationspolyeder vor, deren Stapelabfolge in der Kristallstruktur von AgMg4 zufällig ist, jedoch mit kurzreichweitiger Korrelation. Es konnte gezeigt werden, dass sich AgMg4 in eine Tieftemperaturphase umwandelt, in der die Polyeder vermutlich langreichweitig unter Bildung einer Überstruktur ordnen. Der Phasenbestand des ternären Systems Ag-Ga-Mg wurde untersucht und die Kristallstrukturen von sechs neuen Phasen bestimmt. Des weitern wurde eine Verbindung im System Ga-Mg-Pd charakterisiert. Anhand der Strukturtypen Al3Ir und Cu3P sowie den Verbindungen Ag0,55Ga0,45Mg3, Ga4,62Mg13,38Pd7 und Ag1,31Ga1,89Mg7,80 wurde gezeigt, wie die Variation von Strukturmotiven durch geringe Abweichungen von idealer Symmetrie zu zunehmend komplexeren Kristallstrukturen führt, die sich stets von Packungen des Edshammarpolyeders ableiten lassen. Drei ternäre Phasen vom I3-Cluster-Typ konnten identifiziert werden: Neben ternären Varianten der Phasen Ag7Mg26 und Ag17Mg54 kristallisiert Ag0,59Ga0,41Mg2 metastabil im NiTi2-Typ. In den strukturchemisch verwandten Phasen Ag6Ga12Mg11 und Ag21Ga74Mg44 bilden die Mg Atome Netzwerke mit Clatrath-II- bzw. Clatrath-IV-Topologie, die mit Ikosaedern und Frank-Kasper-Polyedern aus Ag und Ga gefüllt sind. Diese Phasen werden wahrscheinlich durch das e/a-Verhältnis der gesamten Struktur im Sinne einer Hume-Rothery-Regel stabilisiert.

One of the key responsibilities of Getinge's ventilators is to deliver accurate gas volumes to patients. To ensure this precision, specially designed rigid steel tanks are utilized to evaluate the performance and precision of the ventilators in providing exact air volume. The intention of this study is to design and implement a suitable controller for actuating a servo piston pump in order to be used for the tank volume measuring and calibration process. Two controlling strategies were chosen for this purpose: Linear Quadratic Regulator (LQR) and Fractional Order Proportional Integral Derivative (FOPID). This work also aimed to establish a narrative of the two controlling strategies after optimizing them using genetic algorithm optimization (GA) and evaluating their effectiveness in controlling a brushless DC motor (BLDC) actuating a servo piston pump. This involved modeling the system in Matlab and Simulink based on the mathematical representations of the system's dynamics, specifically focusing on its pneumatic behavior. The nonlinear model was linearized and served as a basis for the controllers' optimization through the genetic algorithm. Both controller designs were then compared in both the Simulink environment and the actual physical system. The results show that the FOPID exhibits superior performance in the Simulink environment. Contrariwise, the LQR displays a far greater level of superiority in the physical system, whereas the FOPID performance significantly deteriorated upon implementation in the physical system. Furthermore, the study suggests implementing anti-windup techniques and ensuring the accurate digitization of fractional calculus for further research to enhance the performance of the FOPID controller on the physical system. / En av de centrala uppgifterna för Getinges ventilatorer är att leverera exakta gasvolymer till patienter. För att säkerställa denna precision används speciellt designade ståltankar för att bedöma ventilatorernas funktion och precision att leverera exakt luftvolym. Syftet med denna studie är att utforma och implementera en lämplig Styrenhet för att aktivera en servokolvspump som ska användas för tankvolymens mätning och kalibreringsprocess. Två styrstrategier valdes för detta ändamål: Linear Quadratic Regulator (LQR) och Fractional Order Proportional Integral Derivative (FOPID). Arbetet kommer också att syfta till att etablera ett narrativ för de två styrstrategierna efter att ha optimerat dem med genetisk algoritmoptimering (GA) och utvärderat deras effektivitet vid styrning av en borstlös DC-motor som aktiverar en servokolvspump. Detta innefattade modellering av systemet i Matlab och Simulink baserat på de matematiska representationerna av systemdynamiken, med speciellt fokus på dess pneumatiska beteende. Den icke-linjära modellen linjäriserades och fungerade som grund för regulatorernas optimering genom den genetiska algoritmen (GA). Båda regulatorernas utformningar jämfördes sedan både i Simulink-miljön och det fysiska systemet. Resultaten visar att FOPID uppvisar överlägsen prestanda i Simulink-miljön. Å andra sidan visar sig LQR vara överlägsen i det fysiska systemet, medan FOPID-prestandan försämras avsevärt vid implementering i det fysiska systemet. Dessutom föreslår studien att implementera anti-windup-tekniker och säkerställa korrekt digitalisering av fraktionell kalkyl för vidare forskning för att förbättra prestanda för FOPID-regulatorn på det fysiska systemet.

This research report focuses on the origin and development of the Medingen Mission Station, near Ga-Kgapane in the Limpopo Province, and the provision of education at this station since its establishment in 1881. After an account of missionary endeavours in South Africa during the second half of the nineteenth century (with the emphasis on the activities of the Berlin Missionary Society), an explanation is provided of how missionaries became involved in the weal and woes of the Balobedu tribe. This is followed by an indication of how Reverend Fritz Reuter took the initiative to provide basic education to the inhabitants of Ga-Kgapane and how education provision developed at Medingen since then. Reasons are advanced for the prominence Medingen Primary School currently enjoys and the study concludes with the assertion that Medingen Mission Station can be regarded as an important, though not exclusive source of the Balobedu’s present-day identity. / Educational Foundations / M.Ed. (History of Education)

This thesis aims to review and analyze the scheduling problem in general and Job Shop Scheduling Problem (JSSP) in particular and the solution techniques applied to these problems. The JSSP is the most general and popular hard combinational optimization problem in manufacturing systems. For the past sixty years, an enormous amount of research has been carried out to solve these problems. The literature review showed the inherent shortcomings of solutions to scheduling problems. This has directed researchers to develop hybrid approaches, as no single technique for scheduling has yet been successful in providing optimal solutions to these difficult problems, with much potential for improvements in the existing techniques. The hybrid approach complements and compensates for the limitations of each individual solution technique for better performance and improves results in solving both static and dynamic production scheduling environments. Over the past years, hybrid approaches have generally outperformed simple Genetic Algorithms (GAs). Therefore, two novel priority heuristic rules are developed: Index Based Heuristic and Hybrid Heuristic. These rules are applied to benchmark JSSP and compared with popular traditional rules. The results show that these new heuristic rules have outperformed the traditional heuristic rules over a wide range of benchmark JSSPs. Furthermore, a hybrid GA is developed as an alternate scheduling approach. The hybrid GA uses the novel heuristic rules in its key steps. The hybrid GA is applied to benchmark JSSPs. The hybrid GA is also tested on benchmark flow shop scheduling problems and industrial case studies. The hybrid GA successfully found solutions to JSSPs and is not problem dependent. The hybrid GA performance across the case studies has proved that the developed scheduling model can be applied to any real-world scheduling problem for achieving optimal or near-optimal solutions. This shows the effectiveness of the hybrid GA in real-world scheduling problems. In conclusion, all the research objectives are achieved. Finaly, the future work for the developed heuristic rules and the hybrid GA are discussed and recommendations are made on the basis of the results.

This research is focused on the integration problem of process planning and scheduling in steel heat treatment operations environment using artificial intelligent techniques that are capable of dealing with such problems. This work addresses the issues involved in developing a suitable methodology for scheduling heat treatment operations of steel. Several intelligent algorithms have been developed for these propose namely, Genetic Algorithm (GA), Sexual Genetic Algorithm (SGA), Genetic Algorithm with Chromosome differentiation (GACD), Age Genetic Algorithm (AGA), and Mimetic Genetic Algorithm (MGA). These algorithms have been employed to develop an efficient intelligent algorithm using Algorithm Portfolio methodology. After that all the algorithms have been tested on two types of scheduling benchmarks. To apply these algorithms on heat treatment scheduling, a furnace model is developed for optimisation proposes. Furthermore, a system that is capable of selecting the optimal heat treatment regime is developed so the required metal properties can be achieved with the least energy consumption and the shortest time using Neuro-Fuzzy (NF) and Particle Swarm Optimisation (PSO) methodologies. Based on this system, PSO is used to optimise the heat treatment process by selecting different heat treatment conditions. The selected conditions are evaluated so the best selection can be identified. This work addresses the issues involved in developing a suitable methodology for developing an NF system and PSO for mechanical properties of the steel. Using the optimisers, furnace model and heat treatment system model, the intelligent system model is developed and implemented successfully. The results of this system were exciting and the optimisers were working correctly.

This thesis investigates stylistic diversity in European 1:50 000 state topographic maps and explores the extent to which national conditions, such as socio-economic, cultural, and demographic characteristics, are intrinsically expressed in their symbolization of the national landscape. The separation of the topographic map from its assumed objectivity and the poststructuralist handling of maps as ‘texts’ provide the point of departure for the theoretical framework, which includes a discussion of the role of aesthetic judgment and the nature of style in cartography, and subsequently develops a new language paradigm for understanding national differences in cartographic expression. The methodology involves the construction of a typology for the classification of the legend symbologies of 1:50 000 paper topographic maps from 20 different European national mapping organizations. In addition to providing a quantitative assessment of the symbols devoted to each type of feature, this incorporates a qualitative classification of their appearance according to the criteria of colour, visual hierarchy, ‘white’ space, and lettering in the search for supranational styles. Although it was possible to group countries using a cluster analysis based on the proportion of symbols within each class, the findings reveal much stylistic diversity in European 1:50 000 state topographical mapping, which is demonstrated further in the graphical appearance of each symbology. Tests of association between the symbol classification data and various national statistics suggest a very general reflection of national conditions and do not support some more plausible links, but nevertheless imply the influence of specifically national circumstances. In order to understand the possible influences of wider geopolitical factors on the design and production of state topographic maps, recent initiatives in Latvia and Slovenia were examined and interviews were conducted with those involved. The findings suggest that even with fundamental changes such as the achievement of political independence, the legacy of former styles of topographic cartography persist, especially concerning how the landscape is classified. The development of national styles in state topographic maps appears to be a process in which only broader, more permanent supranational characteristics, such as functional dependencies within core-periphery systems, may be reflected more accurately.

Subsidence in river deltas is a complex process that has both natural and human causes (Boesch et al., 1994). The Yellow River delta is used for farming, contains an important nature reserve for wild animals especially for waterfowl, has a population of 1.64 million, and is the location of significant oil fields (Chen et al., 2012). Increasing human activities like farming and petroleum extraction are affecting the Yellow River delta, and one consequence is subsidence. This subsidence may have social, economic and environmental impacts (Syvitski et al., 2009). The purpose of this thesis is to measure the surface displacement in Yellow River delta and to investigate the causes of measured displacement. The use of Interferometric Synthetic Aperture Radar (InSAR) for Earth surface displacement mapping has increased since the 1990s when a lot of radar images become available. InSAR time series techniques identify displacement of an area between different image acquisition times. In this study, StaMPS package was employed to process Envisat ASAR images collected between 2007 and 2010. StaMPS selects only the stable pixels from interferograms to maintain the coherence signals over a long time interval. Consistent results between two descending tracks show subsidence with a mean velocity of up to 30 mm/yr in the radar line of sight direction in Gudao Town (oilfield), Gudong oilfield and Xianhe Town of the delta, and also show that subsidence is not uniform across the delta. Field investigation shows an association between areas of subsidence and of petroleum extraction. In a 9 km2 area of the Gu-Dao Oilfield in the delta, InSAR derived surface deformation is used to model the geometry, volume or pressure change of the deformation source, namely the extraction of fluids, using three different models: the spherical source Mogi type model, the finite prolate spheroid model and the poroelastic disk reservoir model. In general, good fits between InSAR observations and modelled displacements are seen. The source depths estimated in the three models agree well with the published oilfield depth. The subsidence observed in the vicinity of the oilfield is thus suggested to be caused by fluid extraction. For Mogi type model, a uniform subsidence rate of about 7 mm/yr is co-estimated. InSAR observations in Xianhe Town in the delta, which is not affected by oil extraction, also shows 8~12 mm/yr uniform subsidence. It is suggested this uniform subsidence is caused by other sources e.g. loading and sediment compaction. Since InSAR only measures relative displacement, accurate determination of small uniform rate need the reference phase provided by other observations e.g. GPS and levelling. Mogi model provides the volume change in Gudao oilfield. The ellipsoidal source and the disk reservoir model the pressure changes. Additional reservoir information e.g. material parameter will help better confine the model parameters. Although no production data is available for comparison, the volume and pressure changes obtained from the models, together with InSAR observed displacement might be of interest for oil industry, to predict future subsidence in Gudao oilfield.

This thesis studies the effectiveness of bio-inspired optimization algorithms in controlling adaptive antenna arrays. Smart antennas are able to automatically extract the desired signal from interferer signals and external noise. The angular pattern depends on the number of antenna elements, their geometrical arrangement, and their relative amplitude and phases. In the present work different antenna geometries are tested and compared when their array weights are optimized by different techniques. First, the Genetic Algorithm and Particle Swarm Optimization algorithms are used to find the best set of phases between antenna elements to obtain a desired antenna pattern. This pattern must meet several restraints, for example: Maximizing the power of the main lobe at a desired direction while keeping nulls towards interferers. A series of experiments show that the PSO achieves better and more consistent radiation patterns than the GA in terms of the total area of the antenna pattern. A second set of experiments use the Signal-to-Interference-plus-Noise-Ratio as the fitness function of optimization algorithms to find the array weights that configure a rectangular array. The results suggest an advantage in performance by reducing the number of iterations taken by the PSO, thus lowering the computational cost. During the development of this thesis, it was found that the initial states and particular parameters of the optimization algorithms affected their overall outcome. The third part of this work deals with the meta-optimization of these parameters to achieve the best results independently from particular initial parameters. Four algorithms were studied: Genetic Algorithm, Particle Swarm Optimization, Simulated Annealing and Hill Climb. It was found that the meta-optimization algorithms Local Unimodal Sampling and Pattern Search performed better to set the initial parameters and obtain the best performance of the bio-inspired methods studied.

Groundwater contamination is a very serious problem as it leads to the depletion of water resources. Seawater intrusion is a special category of groundwater contamination that threatens the health and possibly lives of many people living in coastal areas. The focus of this work is to develop a numerical model to study seawater intrusion and its effects on groundwater quality and develop a control method to effectively control seawater intrusion. Two major approaches are used in this study: the first approach is the development of a finite element model to simulate seawater intrusion; the second is the development of a simulation-optimization model to study the control of seawater intrusion in coastal aquifers using different management scenarios. The simulation-optimization model is based on the integration of a genetic algorithm optimization technique with the transient density-dependent finite element model developed in this research. The finite element model considers the coupled flow of air and water and solute transport in saturated and unsaturated soils. The governing differential equations include two mass balance equations of water and air phases and the energy balance equation for heat transfer, together with a balance equation for miscible solute transport. The nonlinear governing differential equations are solved using the finite element method in the space domain and a finite difference scheme in the time domain. A two dimensional finite element model is developed to solve the governing equations and provide values of solute concentration, pore water pressure, pore air pressure and temperature at different points within the region at different times. The mathematical formulation and numerical implementation of the model are presented. The numerical model is validated by application to standard examples from literature followed by application to a number of case studies involving seawater intrusion problems. The results show good agreement with previous results reported in the literature. The model is then used to predict seawater intrusion for a number of real world case studies. The developed model is capable of predicting, with a good accuracy, the intrusion of seawater in coastal aquifers. In the second approach, a simulation-optimization model is developed to study the control of seawater intrusion using three management scenarios: abstraction of brackish water, recharge of fresh water and combination of abstraction and recharge. The objectives of these management scenarios include minimizing the total costs for construction and operation, minimizing salt concentrations in the aquifer and determining the optimal depths, locations and abstraction/recharge rates for the wells. Also, a new methodology is presented to control seawater intrusion in coastal aquifers. In the proposed methodology ADR (abstraction, desalination and recharge), seawater intrusion is controlled by abstracting brackish water, desalinating it using a small scale reverse osmosis plant and recharging to the aquifer. The simulation-optimization model is applied to a number of case studies. The efficiencies of three different scenarios are examined and compared. Results show that all the three scenarios could be effective in controlling seawater intrusion. However, ADR methodology can result in the lowest cost and salt concentration in aquifers and maximum movement of the transition zone towards the sea. The results also show that for the case studies considered in this work, the amount of abstracted and treated water is about three times the amount required for recharge; therefore the remaining treated water can be used directly for different proposes. The application of ADR methodology is shown to be more efficient and more practical, since it is a cost-effective method to control seawater intrusion in coastal aquifers. This technology can be used for sustainable development of water resources in coastal areas where it provides a new source of treated water. The developed method is regard as an effective tool to control seawater intrusion in coastal aquifers and can be applied in areas where there is a risk of seawater intrusion. Finally, the developed FE model is applied to study the effects of likely climate change and sea level rise on seawater intrusion in coastal aquifers. The results show that the developed model is capable of predicting the movement of the transition zone considering the effects of sea level rise and over-abstraction. The results also indicate that the change of water level in the sea side has a significant effect on the position of the transition zone especially if the effect of sea level rise is combined with the effect of increasing abstraction from the aquifer.

The study entitled “ The portrayal of female characters in the three dramas by Serudu, entails describing female oppression by males in the three dramas, A mo swina ngwanana thakana, Kelelagobedi, Šaka la pelo ga le tlale. Chapter one depicts the aim of the study, identification of the problem, other researchers who have tried to research about Serudu’s three dramas namely A mo swina ngwanana thakana, Kelelagobedi and Šaka la pelo ga le tlale, the method to be used and delianation of chapters. Chapter two will deals with the definition of concepts namely: - Drama - Characters - Feminism - Womanism Chapter three will give the summary of the three dramas and the application of Feminism and Womanist theories with reference to the three dramas. Chapter four will be the concluding remarks stating the generalisation of all chapters and the recommendation thereof. / Ms. R Mokgathi