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This thesis investigates the WCSPH model by considering fluid entry and exit, and integrates the WCSPH method into a new, novel, particle-based Bluff Morphology Model (BMM). Using the BMM, this thesis investigates the stability, collapse and equilibrium position of soft coastal bluffs (cliffs). Fluid and floating object interaction using a novel adaptation of the WCSPH method is investigated by incorporating a floating object model. In particular, this thesis examines the water impact, hydrodynamic forces, fluid motions, and movement of objects in the conventional case studies of object entry and exit from still water. A two-dimensional wedge drop analysis was examined, and the hydrodynamic forces show acceptable agreement with published experimental and numerical results. Simulations for water entry and exit of a buoyant and neutral density cylinder compares well with the previous experimental, numerical and empirical studies. These results provide a good foundation to evaluate the accuracy and stability of WCSPH for modelling complex flows, and therefore offers a platform for the use of WCSPH in a Bluff Morphology Model. The BMM combines a multiple wedge displacement method with an adapted Weakly Compressible Smoothed Particle Hydrodynamics (WCSPH) method. At first the wedge method is applied to compute the stability of the bluff. Once the critical failure mechanism of the bluff slope has been identified, if the Factor of Safety for the mechanism is less than 1, the adapted WCSPH method is used to predict the failure movement and residual shape of the slope. The model is validated against benchmark test cases of bluff stability for purely frictional, purely cohesive, and mixed strength bluff materials including 2D static water tables. The model predictions give a good correlation with the expected values, with medium resolution models producing errors of typically less than 2.0%. In addition, the prediction of lateral movement of a surveyed cliff and the dynamic collapse of a vertical bluff are computed, and compare well with published literature. This model is further extended to then investigate the effect of two dimensional seepage on the stability and collapse of soil slopes and levees. To incorporate the seepage in the model, Darcy’s Law is applied to the interactions among neighbouring soil particles and ghost particles are introduced along the enclosed soil boundary to ensure that no fluid crosses the boundary. The contribution of partially saturated soils and matric suction, as well as the change in hydraulic conductivity due to seepage, are predicted well by this model. The predicted time evolution of slope stability and seepage induced collapse are in reasonable agreement with the experimental results for homogeneous frictional sand and multiple layered cohesive soils. Rapid drawdown over a sand soil is also investigated, and the location and time of the levee collapse occurrence are captured well. A toe erosion model is incorporated within the numerical model, and the location and quantity of erosion caused by lateral seepage is well predicted. The interplay of erosion, seepage and slope instability is examined.

Approved for public release, distribution is unlimited / This thesis presents the possible scenarios for the final political status of Kosovo, undecided since 1999, and the implications of these scenarios for the stability of the Balkans. In the beginning, basic elements of theory about the reconstruction of war-torn societies are presented in terms of such aspects as security, governance, economy, and justice. The goal is an understanding of the current situation in Kosovo, the challenges that the international administration had to handle when it arrived in Kosovo in June 1999, and its achievements and weaknesses till now. Finally, the possible scenarios for Kosovo's final status are examined and the one best for regional stability is suggested. / Commander, Hellenic Navy

In this paper we stress test the banking sectors of the PIIGS countries. We focus in particular on modeling the credit risk and estimating the impact of changes in macroeconomic variables on the level of capital adequacy. We develop two scenarios - a baseline stress testing scenario and an adverse scenario. The results indicate that under both scenarios, the analyzed banking systems have some capital adequacy issues. We find that the Portuguese banking sector is facing biggest capitalization problems. Number of undercapitalized banks under the adverse scenario is bigger than in baseline scenario for all the countries. Another finding which is common for all the countries is that large-sized privately owned banks are better capitalized than small and medium-sized ones. Last finding concerns ownership structure where we have found that all the state-owned banks are undercapitalized in both scenarios. JEL Classification F12, F21, C53, E37, G21, G28 Keywords bank, credit risk, macro stress testing, PIIGS Author's e-mail igor.vukic@gmail.com Supervisor's e-mail adibabin@gmail.com

This thesis describes the design of multivariable excitation controllers for synchronous generators, and their practical implementation on a laboratory machine system. The main objectives of the investigation were aimed at extending the steady-state stability limit of the generator and improving its general controllability. The present work is principally concerned with the implementation and test of the designs. Instrumentation has been developed to measure and combine feedback signals; this instrumentation and the laboratory generator system are described in detail. The performances of the controllers are predicted by computer simulation and evaluated by practical testing; attention is focussed on comparison of predicted and experimental performances. The theoretical basis of the design strategy is described, in which an optimal control algorithm applies the system states as feedback signals to the open-loop system, thereby shifting certain of the system eigenvalues to more desirable, predetermined locations. The state variables are selected as physically measurable quantities which obviates the need for implementing state estimation techniques.

Faculty of Orthodontics School of Health Sciences 81/0315/8 Miltstein@global.co.za / The incidence of relapse following orthodontic treatment has always been of paramount interest to clinicians and research workers. Many investigations have been carried out at various Universities to assess the long-term stability of orthodontic treatment. This study assessed the stability of 31 cases at least ten years out of retention treated by post-graduate students in the Department of Orthodontics at the University of the Witwatersrand, Johannesburg. Associations between certain clinical parameters and postretention relapse were also evaluated. Occlusal changes which had taken place were assessed by evaluating data from models taken prior to treatment and comparing these with similar parameters at the end of treatment and, on average, just less than 13 years following the end of retention. Eleven parameters were recorded and measured according to a scoring system proposed by Sadowsky and Sakols. A total malocclusion score was obtained for each study model by calculating the algebraic sum of all the scores. The total malocclusion scores thus indicated the severity of malocclusion presented by each study model at each period. A further examination of each of the study models was carried out in order to establish the Irregularity Index. The anatomic points at which contact would be made were defined on each surface of the six mandibular anterior teeth. The distance between the contact points of the adjacent teeth were measured using a digital vernier caliper calibrated to the nearest 0,05mm. The sum of these 5 measurements provided the Irregularity Index. Values for mandibular irregularity were then grouped into minimal, moderate and severe categories. v Changes in the intercanine and intermolar widths were correlated with overbite, overjet and anterior mandibular crowding parameters. The study also determined whether the presence or absence of third molar teeth and/or premolar extraction therapy were associated with relapse. At postretention 54.8 percent of the sample displayed some degree of relapse in at least one of the variables studied. However, all of the variables studied showed a greater degree of stability than relapse. Canine relationship showed the most postretention stability, whilst deep bite, overjet and molar relationships showed the least. With a few exceptions, occlusal abnormalities which were considered to be severe at the commencement of treatment demonstrated a high degree of stability following corrective therapy, whereas the relapse of mild to moderate features prior to treatment was not as predictable. The small amount of change noted in intercanine and intermolar widths at all three stages of treatment were not significant predictors of relapse at the 5 percent significance level of the parameters assessed. Furthermore the presence or absence of third molar teeth was not a significant predictor of poor postretention malocclusion score, overjet or overbite. Similarly extraction therapy was not a significant predictor of lower incisor alignment relapse (p=1.0). The mean irregularity index of the whole sample following retention indicated that the lower incisors displayed minimal crowding (2.7 mm). Following at least ten years out of retention, treated cases in the Department of Orthodontics, University of the Witwatersrand, Johannesburg showed a high degree of stability for the parameters assessed.