The main goal of this work is to assess ground water contamination at the Přerov airport as a consequence to oil products leakage. For this purpose a flow and transport model was created. Another goal is to create and assess several variations of unfavorable scenarios in terms of water quality. The final goal is to create a set of recommendations for the entire area.

This thesis deals with the assessment of the current state of flood protection in Brno, Pisárky and the Staré Brno district on the Svratka river at km 37.053 to 41.116 and the subsequent design and assessment of flood protection measures. Hydraulic calculations were carried out using the coupled 1D / 2D numerical model of water flow to pass peak flows Q1, Q5, Q20, Q100 a Q100 unaffected. The results are processed in the form of inundation maps and drawing documentation.

Dès le début du 20ème siècle, les eaux souterraines de l’aquifère transfrontalier Milk River (MRA) ont constitué une importante ressource dans le sud de l’Alberta (Canada) et le nord du Montana (USA). L’utilisation intensive de cette ressource sous un climat semi-aride a provoqué une baisse importante des niveaux d’eau localement, si bien que des inquiétudes concernant la pérennité du MRA sont apparues dès les années 60. Les études précédentes du MRA étaient limitées par les frontières nationales, empêchant ainsi une compréhension complète de la dynamique de l’aquifère. L’objectif de cette thèse était de réaliser une étude transfrontalière du MRA afin de caractériser cette ressource régionale d’eau souterraine selon ses limites naturelles. À cette fin, trois modèles transfrontaliers ont été réalisés: un modèle géologique, un modèle conceptuel hydrogéologique et un modèle numérique d’écoulement souterrain. Des travaux de terrain de part et d’autre de la frontière Canada/USA et une revue de littérature exhaustive des études précédentes ont supporté la réalisation de ces modèles. De plus, une première évaluation des niveaux d’exploitation historiques du MRA a été réalisée en Alberta.Le modèle géologique 3D (50 000 km2) représente le MRA (Membre Virgelle de la Formation Milk River/Eagle) et ses unités confinantes continûment à travers la frontière internationale. Le développement de ce modèle a requis une harmonisation des nombreuses nomenclatures stratigraphiques de la région et la délimitation transfrontalière du MRA.Le modèle conceptuel hydrogéologique du MRA a montré deux flux d’écoulement souterrains transfrontaliers, dirigés du Montana vers l’Alberta. La Milk River intercepte la majeure partie du flux souterrain venant du sud, si bien que l’écoulement au nord de la rivière est très faible. Les analyses isotopiques confirment que les eaux du MRA sont principalement fossiles à l’exception de la zone de recharge située le long de la zone d’affleurement du MRA. Les zones du MRA avec une forte conductivité hydraulique et de faibles concentrations en chlorures correspondent à des voies d’écoulement préférentielles. L’émergence des eaux du MRA a lieu via la drainance à travers les unités confinantes notamment le long des vallées enfouies.Le modèle numérique (26 000 km2) d’écoulement souterrain du MRA en régime permanent est une transposition des modèles géologique et conceptuel. Il montre que le modèle conceptuel précédemment développé est hydrauliquement plausible. Le modèle d’écoulement donne une meilleure compréhension du système aquifère en représentant la dynamique de l’écoulement souterrain dans la situation pré-exploitation. Le traçage de particules indique des temps de résidence advectifs de près de 750 000 ans à la limite nord du MRA, ce qui est inférieur aux âges obtenus par les analyses isotopiques (2 Ma).Les bilans en eau des modèles conceptuels et numériques montrent tous les deux que l'extraction de l'eau souterraine dépasse de loin la recharge au nord de la Milk River.Un modèle d'écoulement transitoire serait requis pour définir le volume d'eau provenant de l'emmagasinement dans le MRA et préciser le rôle des aquitards durant le pompage. Par ailleurs, en tant que ressource internationale partagée, une gestion transfrontalière des eaux du MRA serait justifiée dans la région comprise entre la zone de recharge au Montana et le sud de la Milk River en Alberta. Ainsi, ces trois modèles transfrontaliers du MRA forment une base commune internationale de connaissances scientifiques à l'échelle de l'aquifère et pourraient supporter l'évaluation future du meilleur usage possible de cette ressource partagée et limitée. De futurs travaux peuvent inclure l'effet des champs de gaz localisés aux limites du MRA et les conditions paléo-hydrogéologiques liées à l'évolution géochimiqie de l'au souterraine. / Since the beginning of the 20th century, groundwater from the Milk River Aquifer (MRA) has been an important water resource in southern Alberta (Canada) and northern Montana (USA). The intensive use of this resource under a semi-arid climate has locally led to important drops in waters levels, thus raising concerns on the MRA sustainability since the 1960’s. Previous MRA studies were limited by the national boundaries, thus preventing a full understanding of the aquifer dynamics. The objective of this thesis was to carry out a transboundary study of the MRA to define this regional groundwater resource within its natural boundaries. For this purpose, three cross-border models were developed: a geological model, a conceptual hydrogeological model and a numerical groundwater flow model. These developments were supported by focused field work on both sides of the Canada/USA border and a comprehensive review of previous studies. Furthermore, a first assessment of the historical exploitation levels of the MRA was done for southern Alberta.The 3D geological model (50,000 km2) continuously represents the MRA (Virgelle Member of the Milk River/Eagle Formation) and confining units through the international border. Development of this model required harmonization of various stratigraphic nomenclatures in the study area and the transboundary delineation of the MRA extent.The hydrogeological conceptual model of the MRA indicated two transboundary groundwater fluxes from Montana to Alberta. The Milk River intercepts most of the groundwater flux incoming from the south, thus leading to limited groundwater flow north of the Milk River. Isotopic analyses confirm that the MRA contains mostly fossil groundwater, with the exception of the recharge area located along the outcrop area of the aquifer. Areas within the MRA with a high hydraulic conductivity and low chloride concentrations correspond to preferential groundwater flowpaths. Discharge from the aquifer occurs as vertical leakage through the overlying confining units, especially along bedrock valleys.The numerical steady-state groundwater flow model of the aquifer system (26,000 km2) is a transposition of the geological and conceptual models, and it shows that the previously developed conceptual model is hydraulically plausible. The groundwater flow model provides a better understanding of the aquifer system by representing the dynamics of groundwater flow under pre-development conditions. Particle tracking indicates advective residence times of up to 750,000 years in the northern limit of the aquifer, which is lower than ages obtained from isotopic analyses (2 Ma).The area south of the Milk River benefits from all of the transboundary groundwater flux from Montana whereas north of the Milk River, only a portion of the recharge flux coming from the south is transmitted due to the interception of the Milk River.Groundwater budgets from both the conceptual and numerical models show that groundwater extraction far exceeds recharge north of the Milk River. A transient model would be required to determine how much water is derived from storage in the MRA and to assess the role of the confining units during pumping. Furthermore, as an internationally shared resource, a transboundary management of the MRA would be appropriate, especially in the area comprised between the recharge area in Montana and the Canadian reach of the Milk River.Together, these transboundary models of the MRA constitute a common international basis of scientific knowledge at the aquifer scale and could support further assessments of the best possible exploitation of the shared but limited resource.Future works could include the study of the effects of the gas fields located at the limits of the MRA as well as paleo-hydrogeological conditions relative to the geochemical evolution of groundwater.

Generating an adverse pressure gradient (APG), using a rotating cylinder in the proximity of a plane wall under a laminar freestream flow, is studied numerically in this work. The magnitude of the generated APG is a function of the gap, G, between the cylinder and the wall, and the rotational speed of the cylinder, Ω. The flow in such a configuration is characterized by periodic transient vortex shedding at high Reynolds number. A numerical model for the computation of the transient flow for this configuration is developed using the ANSYS CFD simulation tool. The model is validated against published experimental and numerical data for similar flow configurations and excellent agreement is observed. A parametric study is carried out for different combinations of G and Ω for two different Reynolds numbers of 200 and 1000 to examine the development of the resulting separation bubble due to the generated APG. The mechanism of the boundary layer separation over the plane wall and the corresponding wake dynamics is investigated. Results are presented in terms of the distribution of the pressure coefficient as well as skin friction coefficient along the wall and flow patterns around and downstream of the cylinder in the proximity of the wall. The results of these computations confirm that using a rotating cylinder over a plane wall in a freestream flow is an effective technique to generate a controlled range of adverse pressure gradients.

A finite element (FE) model for the generation of single fiber action potentials (SFAPs) in a muscle undergoing various degrees of fiber shortening has been developed. The muscle is assumed to be fusiform with muscle fibers following a curvilinear path described by a Gaussian function. Different degrees of fiber shortening are simulated by changing the parameters of the fiber path and maintaining the volume of the muscle constant. The conductivity tensor is adapted to the muscle fiber orientation. At each point of the volume conductor, the conductivity of the muscle tissue in the direction of the fiber is larger than that in the transversal direction. Thus, the conductivity tensor changes point-by-point with fiber shortening, adapting to the fiber paths. An analytical derivation of the conductivity tensor is provided. The volume conductor is then studied with an FE approach using the analytically derived conductivity tensor (Mesin, Joubert, Hanekom, Merletti&Farina 2006). Representative simulations of SFAPs with the muscle at different degrees of shortening are presented. It is shown that the geometrical changes in the muscle, which imply changes in the conductivity tensor, determine important variations in action potential shape, thus affecting its amplitude and frequency content. The model is expanded to include the simulation of motor unit action potentials (MUAPs). Expanding the model was done by assigning each single fiber (SF) in the motor unit (MU) a random starting position chosen from a normal distribution. For the model 300 SFs are included in an MU, with an innervation zone spread of 12 mm. Only spatial distribution was implemented. Conduction velocity (CV) was the same for all fibers of the MU. Representative simulations for the MUAPs with the muscle at different degrees of shortening are presented. The influence of interelectrode distance and angular displacement are also investigated as well as the influence of the inclusion of the conductivity tensor. It has been found that the interpretation of surface electromyography during movement or joint angle change is complicated owing to geometrical artefacts i.e. the shift of the electrodes relative to the muscle fibers and also because of the changes in the conductive properties of the tissue separating the electrode from the muscle fibers. Detection systems and electrode placement should be chosen with care. The model provides a new tool for interpreting surface electromyography (sEMG) signal features with changes in muscle geometry, as happens during dynamic contractions. / Dissertation (MEng (Bio-Engineering))--University of Pretoria, 2008. / Electrical, Electronic and Computer Engineering / MEng (Bio-Engineering) / unrestricted

No description available.

京都大学 / 新制・課程博士 / 博士(工学) / 甲第23862号 / 工博第4949号 / 新制||工||1773(附属図書館) / 京都大学大学院工学研究科都市社会工学専攻 / (主査)教授 角 哲也, 准教授 竹門 康弘, 准教授 Kantoush Sameh / 学位規則第4条第1項該当 / Doctor of Philosophy (Engineering) / Kyoto University / DFAM

The last two decades have seen new insights, data and analytical methods to establish the behaviour of structures in fire. These methods have slowly migrated into practice and now form the basis for modern quantitative structural fire engineering. This study presents a novel methodology for determining the imposed heat fluxes on structural members. To properly characterise the temperature rise of the structural elements, a post-processing model for computational fluid dynamics tools was developed to establish the heat fluxes imposed on all surfaces by a fire. This model acts as a tool for any computational fluid dynamics model and works on the basis of well resolved local gas conditions. Analysis of the smoke layer and products of combustion allow for heat fluxes to be defined based on smoke absorption coefficients and temperatures. These heat fluxes are defined at all points on the structure by considering full spatial and temporal distributions. Furthermore, heat fluxes are defined by considering directionality and both characteristic length and time scales in fires. Length scales are evaluated for different structural member geometries, while time scales are evaluated for different structural materials including applied fire protection. It is the output given by this model that provides the input for the thermal analysis of the structural members that is a necessary step prior to the structural analysis to be undertaken. The model is validated against the experimental results of the previously mentioned large scale fire tests, showing good agreement. In addition, comparisons are made to current methods to highlight their potential inadequacies.

Ce travail de thèse s’est inscrit dans le contexte d’utilisation d’un cycle de conversion de l’énergie de type Brayton au CO2 supercritique, pour les réacteurs à neutrons rapides refroidis au sodium (RNRNa). Dans le cas d’une fuite accidentelle dans l’échangeur de chaleur Na − CO2 d’un RNRNa, le CO2, avec une pression opérative d’environ 200 bars, serait injecté dans le sodium liquide qui se trouve à basse pression,provoquant un jet sous-détendu et réactif deCO2 dans le sodium. L’objectif principal de ce travail de thèse était le développement d’un modèle numérique du jet réactif diphasique de CO2 dans du sodium.Un modèle numérique d’un jet sous-détendu non-réactif de gaz dans du liquide, utilisant une approche3D non-stationnaire de type multi-fluide CFD, a été développé. Les résultats numériques ont été validés à travers la comparaison avec résultats expérimentaux obtenus avec mesures optiques. Un modèle décrivant la réaction chimique entre le sodium et le CO2 a été ensuite développé et intégré dans le modèle 3D multi-fluide. Le modèle résultant permet de calculer les profils de température obtenus au sein du jet et sur les parois des tubes de l’échangeur de chaleur. / This PhD work was motivated by the investigations in the frame of supercritical CO2 Brayton cycles as possible energy conversion cycles for the Sodium-cooled Fast nuclear Reactors (SFRs). Following an accidental leakage inside the sodium-CO2 heat exchanger of a SFR, the CO2, having an operating pressure of about 200 bars, would be injected into the low-operatingpressure liquid sodium, creating an underexpanded reactive CO2-into-sodium jet. The goal of this PhD work is the development of a numerical model of the two-phase reactive CO2-into-sodium jet.A numerical model of an underexpanded non-reactive gas-into-liquid jet was developed, adopting a 3D unsteady multi-fluid CFD approach. The numerical results have been validated through the experimental results obtained with a facility employing optical probe technique. A numerical model for the chemical reaction between sodium and CO2 was then developed and integrated into the 3D two-fluid model. The resulting model allows to determine the temperature profiles inside the reactive jet and on the heat exchanger tubes.

Apresenta-se um trabalho numérico e experimental, com o objetivo de estudar o comportamento dos pavimentos de concreto estruturalmente armados, quando submetidos a forças verticais estáticas e repetidas. Avalia-se a contribuição da armadura de flexão, na resistência de placas de concreto apoiadas sobre meio elástico. Verifica-se experimentalmente o modo de ruína de placas submetidas a carregamento monotônico e a carregamento repetido, com e sem armadura, e acompanha-se o desenvolvimento das fissuras no concreto e das deformações no aço. Comparam-se os resultados obtidos, com as recomendações da NBR 6118:2003, para o dimensionamento de estruturas submetidas à fadiga. É desenvolvido modelo numérico capaz de representar a interface do solo com a placa do pavimento, a fissuração do concreto, a contribuição da armadura e o comportamento pós-fissuração. Com auxílio do modelo numérico, validado a partir dos resultados experimentais, estuda-se a influência de alguns parâmetros importantes para o dimensionamento dos pavimentos, tais como: capacidade de suporte da fundação, espessura das placas, área de aço, dimensões das placas em planta, posição de aplicação da força e presença de juntas de transferência de deslocamento. Os resultados experimentais mostram uma significativa contribuição da armadura positiva na resistência de placas isoladas sob forças verticais centradas. Verificou-se que as forças repetidas provocam fadiga do aço e que o número de ciclos depende da deformação provocada na armadura. A partir dos resultados são traçadas diretrizes para o dimensionamento, no qual devem ser considerados os momentos positivos e os negativos, e deve ser feita a verificação da fadiga do concreto e da armadura / A numerical and experimental study on the behavior of structurally reinforced concrete pavement under vertical static and repeated load is presented. The contribution of bending reinforcement to the strength of concrete slab is assessed. It is experimentally verified the fracture of reinforced and plain concrete slabs under monotonic loads and under cyclic loads. The concrete cracking and the strain on steel are monitored. The results are compared to the brazilian code recommendations to the design of structures under fatigue. A numerical model that represents the soil-slab interface, the concrete cracking, the reinforcement contribution and the tension stiffening behavior is developed. Some important parameters to the pavement design are analyzed using this finite element model, whose reliability was verified to experimental results. These parameters are: the soil capacity; the slab thickness; reinforcement ratio; slab dimensions; load positions; and joints conditions. The tests data show an important contribution of the positive reinforcement on the strength of an isolated slab with centered load. It has been verified the fatigue of the steel. The number of cycles depends on the reinforcement strain. The results are used to propose some directions to the design. The positive and negative bending moments have to be considered and the fatigue on the concrete and on the reinforcement has to be verified