Le trail running, course nature de distances, dénivelés et technicités variables, est une discipline récente à la popularité croissante. La performance en trail dépend de nombreux facteurs génétiques, énergétiques, techniques, stratégiques et motivationnels. Parmi ces facteurs, le coût énergétique de la locomotion fait débat. Les études de cette Thèse s'attachent aux corrélations plat/montée de cette variable, au calcul d'un coût en pente à partir d'un coût à plat, à l'influence de la modification forcée de la fréquence de foulée sur l'énergie consommée, et à l'impact de la fatigue générée par un ultra trail sur le coût à plat et en montée. La prise en compte des contraintes musculaires et biomécaniques en trail d'une part, des facteurs influençant l'économie de course d'autre part, ainsi que des résultats de notre principale étude de terrain, nous laissent émettre l'hypothèse que le coût énergétique et ses variations pre/post course à plat/montée, ne sont pas des indicateurs de performance de l'activité. La force, l'endurance de force et le pacing, en plus de la puissance aérobie et de l'endurance, sont les variables testées les mieux corrélées à la performance en ultra trail / Trail running is a discipline with increasing popularity over the last 2 decades. Trail performance depends on many genetic, energetic, technical, strategic and motivational factors. Among these factors, the energy cost of locomotion is debated. The studies in this Thesis focus on the level/graded correlations of this variable, on the calculation of an uphill cost from a level cost, on the influence of a forced modification of stride frequency on running economy, and on the impact of fatigue generated by an ultra trail on level and uphill costs. Taking account of the muscular and biomechanical constraints on the one hand, and the factors influencing the running economy on the other hand, as well as the results of our main field study, we hypothesize that energy cost and its pre/post fatigue variations, are not performance indicators of the activity. Force, endurance of force and pacing, in addition to aerobic power and endurance, are the tested variables best correlated to ultra trail performance

O desempenho de um veículo de passeio em manobras de arrancada em aclives elevados é um fator muito importante a ser considerado no desenvolvimento de um novo projeto ou modificação de um projeto já existente. Este desempenho é influenciado por várias características do veículo, tais como: perfil e forma da curva de torque do motor, massa do veículo, relações de transmissão, tamanho do pneu entre outros. Este trabalho propõe uma metodologia de simulação para prever o desempenho de um veículo com tração dianteira em aclives elevados, através da utilização de um modelo de simulação desenvolvido na plataforma Matlab Simulink. Essa metodologia consiste na validação de um modelo de simulação capaz de representar todo o procedimento que envolve a saída de um veículo em um aclive elevado, levando em consideração a variação da rotação do motor, do pedal do acelerador, acoplamento da embreagem e o acionamento do freio de estacionamento. Uma medição real em veículo foi feita onde se registrou este comportamento e estes dados foram utilizados como valores de entrada no modelo de simulação. Para a correlação do modelo de simulação, foram utilizados os gráficos que representam a variação do espaço percorrido, velocidade e aceleração longitudinal, onde os resultados práticos e teóricos mostraram-se próximos mostrando que o modelo de simulação desenvolvido em MatLab/Simulink é uma opção a ser utilizada, principalmente nas fases inicias de projeto e para otimização de projetos já existentes. / The performance of a passenger vehicle maneuvering uphill sprint high is a very important factor to be considered in developing a new project or modifying an existing project. This performance is influenced by various characteristics of the vehicle, such as profile and shape of engine torque curve, vehicle weight, gear ratios, tire size and others. This paper proposes an analysis methodology to simulate the performance of a vehicle with front wheel drive in high slopes, through the use of a simulation model developed on the Matlab Simulink. This methodology consists in validating a simulation model capable of representing the entire procedure involving the removal of a vehicle in a high slope, taking into account the variation of engine speed, accelerator pedal, the clutch engaging and brake actuation parking. An actual measurement of vehicle was registered where this behavior and these data were used as input values in the simulation model. For the simulation model correlation, It was used the graphs represent the change in the space covered, vehicle speed and vehicle longitudinal acceleration, where the practical and theoretical results proved to be the next showing that the simulation model developed in Matlab/Simulink is an option be used, especially in the early stages of design and optimization of existing designs.

The flow pattern in the uphill teeming process has been found to be closely related to the quality of ingots and further to affect the yield of ingot production, which is crucial for the steel making process. The formation of non-metallic inclusion and entrapment of mold flux has been considered to be affected by the flow pattern in the gating system and molds by many previous researchers. The aim of this study is to investigate the flow pattern of steel in the gating system and molds during the initial filling stage. In addition, to study the utilization of swirl blade implemented at the bottom of the vertical runner on the improvement of initial filling condition in the mold. A three dimensional model of two molds gating system for 6.2 ton ingots from Scana Steel was adopted in the present work. A reduced geometry model including one mold and a runner, based on the method from previous researchers, was also used for comparison with the current more extensive model. Moreover, a reduced geometry model including one swirl blade and a runner was simulated to find effects of an increased-length vertical runner on the flow pattern improvement at the vertical runner outlet. Flow pattern, hump height and wall shear stress were respectively studied. A reduced geometry with homogenous inlet conditions fails to describe the fluctuating conditions present as the steel enters the mold. However, the trends are very similar when comparing the (hump height-surface height) evolution over time. The implementation of swirl blades gives a chaotic initial filling condition with a considerable amount of droplets being created when steel enters the molds during the first couple of seconds. However, a more calm filling condition with less fluctuation is achieved at the molds after a short while. Moreover, the orientation of the swirl blades affects he flow pattern of the steel. A proper placement of a swirl blade improves the initial filling conditions. The utilization of swirl blades might initially result in larger hump height. However, it gives fewer fluctuations as the casting proceeds. In the model without swirl blades, the maximum wall shear stress fluctuates with a descending trend as the filling proceeds. An implementation of swirl blades can decrease and stabilize the wall shear stress in the gating system. A special attention should be made in choosing refractory at the center stone, the horizontal runner near center stone and the vertical runner at the elbow. This is where the wall shear stress values are highest or where the exposure times are long. / QC 20120203

This thesis has been carried out as a development project at Scana Steel Björneborg with the purpose to study the influential parameters in argon shrouded ingot casting during the manufacturing of low-alloy steels. In the first stage, a literature study was conducted in order to investigate the theoretical background of the procedure and the importance of protecting the melt during ingot casting. Next, a computer model of the shield was designed using COMSOL Multiphysics® with regard to the process conditions at Scana Steel Björneborg. The effect of various parameters on the process was examined through simulations of the argon gas flow pattern, heat transfer between the gas and the melt stream, and the chemical species transport in the gas around the melt stream. Based on the simulation results, two different shapes of shield were proposed for the argon shrouding operation. A set of implementation tests was executed in order to check the installation and usage conditions of the two new shields. After deciding the proper shape of the shield, a full-scale ingot-casting test was performed with the selected shield to investigate the protection behavior. Moreover, the impact of the new casting-protection shield on the nitrogen and oxygen contents of steel was examined through sampling and analyzing the steel before and after casting. It was found that the use of the new shield during the uphill ingot casting is an effective way to reduce the final nitrogen and oxygen contents of the casted ingot. Therefore, the new design of the shield can be used as a developed substitute for the protection of the melt stream in the ingot casting operation.