Submitted by Renata Lopes (renatasil82@gmail.com) on 2017-06-22T19:45:32Z No. of bitstreams: 1 gustavomirandateixeira.pdf: 21289543 bytes, checksum: 065f79ef58fa71e8e9917d39cf048fe1 (MD5) / Approved for entry into archive by Adriana Oliveira (adriana.oliveira@ufjf.edu.br) on 2017-08-07T19:26:17Z (GMT) No. of bitstreams: 1 gustavomirandateixeira.pdf: 21289543 bytes, checksum: 065f79ef58fa71e8e9917d39cf048fe1 (MD5) / Made available in DSpace on 2017-08-07T19:26:17Z (GMT). No. of bitstreams: 1 gustavomirandateixeira.pdf: 21289543 bytes, checksum: 065f79ef58fa71e8e9917d39cf048fe1 (MD5) Previous issue date: 2011-07-29 / CAPES - Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / A Simulação de Reservatórios é uma importante área da engenharia de reservatórios. Simuladores são baseados em modelos matemáticos que modelam o escoamento dos fluidos através do meio porosos. Modelos água-óleo incompressíveis são representados por sistemas de equações diferenciais parciais em duas variáveis: pressão e saturação dos fluidos. O problema consiste de um sistema de equações de difícil resolução e que exige o uso de métodos iterativos para aproximar a solução. Neste trabalho foi feita uma comparação entre métodos numéricos que aproximam a solução deste problema através uma abordagem acoplada, utilizando um método implícito e um esquema desacoplado. O sistema desacoplado utiliza um método implícito para obter a solução da equação da pressão, enquanto a solução da saturação é aproximada através dos métodos de Euler Explícito e BDF (Backward Differentiation Formulas). Para resolver as equações no espaço, os métodos de Kurganov-Tadmor e o Esquema Upwind foram utilizados. O Esquema Upwind é um método de primeira ordem, enquanto o Kurganov-Tadmor (KT) é um método central de segunda ordem. Testes foram realizados utilizando diferentes tipos de reservatórios e propriedades da rocha e do óleo. Os resultados foram comparados com soluções precisas para medir o erro numérico introduzido por cada método. Através dos resultados obtidos nesse trabalho foi possível comparar os métodos e observar que a solução através de um esquema desacoplado é mais vantajosa, principalmente ao utilizar o método BDF para resolver a equação da saturação no tempo. Comparando o esquema Upwind com o KT, verificamos que, como esperado, o KT é um método menos difusivo. Nosso trabalho sugere que o uso do método KT em associação com o BDF resulta em um método mais preciso. Por outro lado, o KT é computacionalmente mais custoso do que o Esquema Upwind. Contudo, para produzir resultados com erros numéricos semelhantes aos do KT, o método Upwind chega a ser mais de seis vezes mais lento. / Reservoir simulation is part of an important area of reservoir engineering. Reservoir simulators are based on mathematical models capable of predicting the fluid flow through porous medium. Water-oil incompressible models are represented by a system of differential partial equations in two variables: pressure and the fluid saturation. The system of equations of the problem is not simple to solve and it demands the use of iterative methods to get the approximate solution. In this work we compared a coupled implicit approach and a decoupled scheme. The decoupled system evolves in time using an implicit method to solve the pressure equation solution whereas the solution for the saturation equation is obtained using Explicit Euler and BDF (Backward Differentiation Formulas) methods. The solutions in space discretization use the Kurganov-Tadmor method and the Upwind Scheme. Upwind Scheme is a first-order finite volume based method whereas Kurganov-Tadmor (KT) is a second-order central scheme. Different kinds of reservoir types and different rock and oil properties were used to compare the results with more precise solutions in order to estimate the amount of numerical errors introduced by each method. These results allowed us to quantify the difference between the analyzed methods and to observe that the solution obtained from the decoupled method yields the best results, in particular when the BDF method is used to solve the saturation equation in time. The solution from the BDF method in association with the Upwind Scheme compared with the KT shows that, as expected, the KT method is less diffusive than the Upwind. Our work suggests that the use of the KT method in association with the BDF results in a more accurate method. On the other hand, the KT method is computationally more expensive compared to Upwind Scheme. Nevertheless, to produce numerical results with similar errors to KT, the Upwind Scheme can be more than five times slower.

We present new results on absolute stability for BDF-ADI (Backward differentiation formula Alternating Direction Implicit) methods applied to a linear advection and diffusion equations. Unconditional absolute stability of the BDF2-ADI method is proven for advection and diffusion separately, as well as to the BDF3-ADI method for the purely-diffusive case. Conditional absolute stability of the BDF4-ADI is also proven for the purely-diffusive case, and stability regions for BDF3-ADI and BDF4- ADI are given in terms of the PDE coefficients and numerical parameters. Lastly, numerical experiments are presented to support the theoretical results and conjectures. These experiments also suggest future work.

Des schémas numériques précis et robustes sont proposés pour modéliser les écoulements souterrains et leur couplage avec le ruissellement surfacique. Les écoulements souterrains sont d´écrits par l'équation de Richards (instationnaire) qui est discrétisée par une méthode BDF en temps et une méthode de Galerkine discontinue à pénalisation intérieure symétrique en espace. Des cas tests sur des colonnes d'infiltration confirment la robustesse des schémas choisis. Dans un premier temps, nous considérons des conditions de Signorini pour l'équation de Richards afin de modéliser la présence de drains en fond d'aquifère ou l'affleurement de la nappe en négligeant le ruissellement, c'est-à-dire en supposant que l'eau exfiltrée est immédiatement évacuée du système. Dans un second temps, nous prenons en compte le ruissellement par le biais de conditions de couplage qui imposent l'égalité des flux d'eau échangés et la continuité de la pression à l'interface. Les écoulements superficiels sont d´écrits par l'équation de l'onde cinématique qui constitue une approximation des équations de Saint-Venant. L'équation de l'onde cinématique est discrétisée par une méthode de Godunov. Les deux schémas, pour l'écoulement souterrain et pour l'écoulement superficiel, sont conservatifs et peuvent être utilisés dans des algorithmes de couplage faisant intervenir un ou plusieurs pas de temps. Pour assurer la conservation de la masse d'eau totale du système couplé, les flux à l'interface doivent être convenablement choisis. Nous donnons en particulier la construction de ces flux pour les schémas BDF1 et BDF2. La précision et la robustesse de nos schémas sont évaluées sur plusieurs cas tests dont le drainage d'une lame d'eau, deux cas d'exfiltration de nappe (l'un provoqué par la pluie et l'autre par une injection en fond d'aquifère) et un ruissellement hortonien. Enfin, nous présentons une application concrète portant sur le fonctionnement hydrologique d'un petit bassin versant drainé.

Auf der Grundlage mehrjähriger Datenerhebungen auf Bodendauerbeobachtungsflächen (BDF) wurden Bilanzsalden für Kohlen- und Stickstoff erstellt. Diese dienen als wichtige Indikatoren für die Bodenfruchtbarkeit eines Standortes und für Stoffausträge aus dem Boden in die Umwelt. Der flächendeckend vorhandene BDF-Datenpool ermöglicht gute Bilanzierungsmöglichkeiten der Eintrags- (Düngung, Deposition) und Austragspfade (Sickerwasser, Ernteentzug). Anhand der Wechselwirkungen zwischen den Kompartimenten Boden, Klima und Wasser sowie durch den Einfluss der Bewirtschaftung konnten die Dynamik und Tendenzen der Stoffkreisläufe auf den sächsischen BDF abgeleitet und bewertet werden. Redaktionsschluss: 24.09.2019

Military staff are repeatedly exposed to stressful and unpleasant traumatic life events. These can cause psychological injury, leading to mental and emotional stress. The stigma of mental health problems in military settings runs deeper than in civil society. Being admitted with mental health problems while serving can be a career stopper, but at times can also be associated with cowardice or malingering. It is the primary responsibility of the military to maintain and promote high military/combat readiness among staff. The change in focus of modern military forces, such as the Botswana Defence Force (BDF), with units being deployed more often, places greater demands on troops. Such operations call for increased training exercises, planning sessions and equipment inspections. Training emphasizes discipline and integrity as the core values of the BDF. These form a foundation for healthy and successful coping strategies. The morale of employees is the starting point for measuring their wellness. Morale in the military is embedded in the fitness programs. These are biased towards military training, creating physical fitness, mental alertness and the qualities of military preparedness. The programs are normally involuntary, mandated through the commander, and form part of a soldier‘s military duties. Military recreation, morale and welfare programs were introduced as a way to provide soldiers with the opportunity to relax and rejuvenate. Recreation serves as a powerful tool for achieving an optimal experience, motivating people to change and improve their health and wellness. The problem identified for this study was that members of the BDF were exposed to situations in a military context, as well as in their personal lives, which caused stress. It was postulated that BDF members had little knowledge or the resources to utilize appropriate recreation-related coping strategies. The study aimed primarily to explore the use of sport and recreation activities in military settings as means to reduce and manage stress. To achieve this goal, it was necessary first to determine the current sport and recreation participation of BDF staff members, then to assess their existing stress levels, their overall psychological well-being, and any dysfunctional behaviours resulting from stress. On the basis of these findings, a Therapeutic Recreation Stress Management Intervention Model was proposed, designed to reduce stress and promote the psychological well-being of BDF members. A survey was carried out using a questionnaire. Descriptive statistics were used to summarize the collected data, offering a basic description of the data through frequency distributions, measures of central tendency, variances and relationships. Inferential statistics were used to draw conclusions from the data collected, giving the various factors. The results revealed that the BDF was a male-dominated institution, recruiting soldiers between the ages of 18 and 44, most of whom had some level of education. Most of the staff members came from the lower ranks and had experienced one or more deployments since being recruited into the military. The results further indicated that BDF staff members participated in sport and recreation activities, reflecting an active and healthy lifestyle, with satisfactory levels of involvement. Analysis of stress responses revealed that members experienced stress and that this was related not just to operational or non-operational military stressors but also to personal stressors resulting from their social, financial or emotional conditions. Members of the BDF did not receive the necessary social support from family members and friends to cope with these stressors. The findings on stress in relation to sport and recreation participation revealed that BDF members were intrinsically motivated to embrace healthy lifestyles which could contribute to lower levels of stress. This could even lead to a decrease in stress, supporting the literature which indicates that engaging in physical activities, as part of living a healthy lifestyle, might lead to a reduction in stress levels. The results on the stress-coping measures used by BDF members revealed that recreation activities were deliberately used to cope with stress. Although physical exercise was used as a way of coping with stress, sedentary recreation activities were more prevalent among BDF members. Positive stress-coping measures were adopted by respondents, contrary to the findings of previous studies which indicated that military staff adopted dysfunctional behaviour as a coping measure (e.g. excessive drinking) that formed part of the military culture. The stress-coping abilities of BDF members differed in terms of personal and military demographics from those of previous studies, posting a new contribution to military literature. The results further revealed that BDF members were not sufficiently skilled in coping with stress during military training. This study concluded that the Botswana Defence Force is no different from other military forces, experiencing operational and non-operational stress, as well as personal stress, which need to be addressed. Recommendations were made for further research on stress in military contexts and further guidelines were suggested to the BDF on the use of sport and recreation, together with more specific therapeutic recreation, as ways to reduce stress. A Therapeutic Recreation Stress Management Intervention Model was recommended for further testing in the BDF, as well as in other military forces. / Thesis (DPhil)--University of Pretoria, 2013. / gm2014 / Biokinetics, Sport and Leisure Sciences / unrestricted

Text in English / The study aims to investigate criminal jurisdiction of the visiting SADC armed forces during peace time focusing only on the Republic of Botswana and the Republic of South Africa. Since the adoption of the Declaration and Treaty of SADC, the armed forces of both Botswana and South Africa at times find themselves on each other’s territory. Once in each other’s territory the question of criminal jurisdiction becomes imperative. The two countries seem not to agree on the content of status of force agreements while cooperating in terms of the SADC Treaty. The contentious point is that the death sentence is still a competent sentence for certain offences under certain circumstances in terms of Botswana laws, whereas in South Africa the death sentence was declared unconstitutional. In the absence of any agreement, South African armed forces may face a death sentence while in Botswana and Botswana authorities might not be able to carry out a death sentence over their members for offences committed while in South Africa. In trying to answer the question of criminal jurisdiction while on each other’s territory during peace time, a study of the evolution of jurisdiction is undertaken. The laws of both countries are considered, especially the application and protection afforded by their respective constitutions. The approach followed by the UN in sending a peace-keeping force to conflict areas is analysed. A micro-comparison of agreements concluded by selected countries, more especially the NATO agreement, is undertaken. Treaties as a source of international law are analysed to show that rights can be extended and be limited by agreement. The study concludes by recommending that concurrent criminal jurisdiction with certain qualification seems to be the accepted norm and compromise amongst the international community, and that the two countries may consider this approach as the basis for such agreement. / Public, Constitutional, & International Law / LL.M

Text in English / The study aims to investigate criminal jurisdiction of the visiting SADC armed forces during peace time focusing only on the Republic of Botswana and the Republic of South Africa. Since the adoption of the Declaration and Treaty of SADC, the armed forces of both Botswana and South Africa at times find themselves on each other’s territory. Once in each other’s territory the question of criminal jurisdiction becomes imperative. The two countries seem not to agree on the content of status of force agreements while cooperating in terms of the SADC Treaty. The contentious point is that the death sentence is still a competent sentence for certain offences under certain circumstances in terms of Botswana laws, whereas in South Africa the death sentence was declared unconstitutional. In the absence of any agreement, South African armed forces may face a death sentence while in Botswana and Botswana authorities might not be able to carry out a death sentence over their members for offences committed while in South Africa. In trying to answer the question of criminal jurisdiction while on each other’s territory during peace time, a study of the evolution of jurisdiction is undertaken. The laws of both countries are considered, especially the application and protection afforded by their respective constitutions. The approach followed by the UN in sending a peace-keeping force to conflict areas is analysed. A micro-comparison of agreements concluded by selected countries, more especially the NATO agreement, is undertaken. Treaties as a source of international law are analysed to show that rights can be extended and be limited by agreement. The study concludes by recommending that concurrent criminal jurisdiction with certain qualification seems to be the accepted norm and compromise amongst the international community, and that the two countries may consider this approach as the basis for such agreement. / Public, Constitutional, and International Law / LL.M