MEMS based mechanical switches are seen to be the likely replacements for CMOS based switches due to the several advantages that these mechanical switches have over CMOS switches. Mechanical switches can be used in systems under extreme conditions and also provide more reliability and cause less power loss. A major problem with mechanical switches is bouncing. Bouncing is an undesirable characteristic which increases the switching time and causes damage to the switch structure affecting the overall switch life. This thesis proposes a new switch design that may be used to mitigate bouncing by using two voltage sources using a double electrode configuration. The effect of many switch’s tunable parameters is also discussed and an effective tuning technique is also provided. The results are compared to the current control schemes in literature and show that the double electrode scheme is a viable control option.

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Ce travail de thèse s'articule autour de plusieurs variations sur le thème du rebond d'une goutte d'eau sur une surface non-mouillante. Nous engendrons des rebonds spéciaux que nous caractérisons expérimentalement. Notre analyse de ces rebonds se concentre sur la mise en évidence des paramètres et des phénomènes physiques contrôlant leur extension spatiale et temporelle, deux quantités qu'il est important de comprendre tant d'un point de vue fondamental qu'appliqué. Nous étudions, dans un premier temps, les effets de la géométrie du substrat sur le rebond d'une goutte d'eau. Nous montrons qu'une modification locale, l'ajout d'une macrotexture ponctuelle, crée un mécanisme de rebond nouveau que nous associons à une réduction du temps de contact d'un facteur 2. Nous réalisons également des impacts sur des substrats coniques et sphériques en mettant en avant les différences et les similitudes avec les impacts sur une surface plane. Dans un second temps, nous nous intéressons aux effets créés par un substrat mobile. Nous étudions l'impact de gouttes sur des surfaces déformables et comprenons comment l'échelle de temps du rebond est influencée par une interaction entre celle de la goutte et celle du substrat. Nous discutons aussi l'influence de la déformation du substrat sur le splash. Notre étude de l'influence du mouvement s'est poursuivie en utilisant des surfaces rigides auxquelles nous pouvons imposer un déplacement vertical. En soumettant des gouttes initialement au repos à un mouvement impulsionnel, nous engendrons de surprenantes cavités coniques dont nous modélisons la dynamique. Cette expérience permet de faire un constat étonnant, la faible adhésion des surfaces superhydrophobes est nécessaire à l'obtention des cavités. Nous réalisons des impacts sur une surface dont le déplacement peut-être déclenché au moment du contact entre le liquide et le solide à l’aide du signal provenant d’un capteur de force de type MEMS. Nous atteignons des temps de contact extrêmement réduits, de l’ordre de 20% de celui observé sur le même substrat sans mouvement. Enfin, nous modifions le liquide et non le substrat. Nous montrons que des gouttes jusqu'à 200 fois plus visqueuses que l'eau peuvent rebondir sur des matériaux superhydrophobes. / This thesis revolves around the ability of liquid drops to bounce off superhydrophobic materials. We generate special rebounds and characterize them experimentally.We focus on finding the relevant physical phenomena to describe the temporal and spatial extension of such events, both quantities being of importance from the fundamental and applied point of vue. First, we study the influence of the susbtrate geometry. We modify the surface locally, by introducing a singular macrotexture, and show that it leads to a new bouncing mechanism that shortens the contact time by a factor typically 2. We also modify the substrate at the size of the drop. We perform impacts on non wetting cones and spheres and compare them to what is observed on a flat surface. Then, we study the effect of substrate motion. We make impacts on soft materials that can be deformed by the drop. We show that this situation can lead to fast bouncing and interpret the contact time as the result of an interplay between the timescale of the drop and that of the substrate. We also discuss the influence of substrate deformation on splashing. We go deeper into the effect of substrate motion by using rigid materials which movement we can trigger. We evidence new liquid shapes, conical cavities, by submitting a drop, initially at rest, to a vertical impulse.Surprisingly, the low, but present, adhesion of superhydrophobic materials is the key ingredient needed to observe such shapes. We also work on the effect of motion at the onset of impact, by trigerring the substrate movement using the signal from a MEMS force sensor intregrated in the surface. This setup allow us to reach contact times that represent 20% of the contact time on an immobile substrate. Finally, we change perspective and modify the liquid instead of the solid. We show that viscous drops can bounce as long as their viscosity does not exceed 200 times that of water.

The capability of hand-eye coordination is one of the dexterous skills owned by human beings. In order to reproduce the skillfully operational technique and demonstrate basic hand-eye coordination technique, a robotic wrist system with stereo visual feedback strategy from the viewpoint of table tennis is presented in this thesis. Based on the concept of aerodynamics and collision mechanics, the exerted forces acting on the ball are analyzed. Three stages, including the ball flying in the air, inelastic collision between a racket and the ball, and hitting strategy of humans, will be investigated. At the same time, three-dimensional information for the scene is established using images acquired by dual cameras with a calibration process. Therefore, the flying status of the ball and its position in the space can be calculated. The robotic wrist located underneath will then be controlled to hit the ball to allow it bouncing upwards. The mechanical wrist is operated by three servo motors to simulate actual movement of human wrist. The objective is to successively hit the ball with the racket to achieve intelligent hand-eye coordination control on ball bouncing.

Thesis (M.S.)--Miami University, Dept. of Physical Education, Health, and Sport Studies, 2005. / Title from first page of PDF document. Document formatted into pages; contains [1], v, 188, [6] p. : ill. Includes bibliographical references (p. 162-176).

Contrary to common intuition, free jets of fluid can ``bounce'' off each other on collision in mid-air, through the effect of a lubricating air film that separates the jets. While there has been much work on coalescing jets of fluid and non-coalescence in other systems like drop-drop, drop on a bath, jet on a bath, non-coalescence of fluid jets has been little studied. A simple experimental setup was developed to stably demonstrate and study the non-coalescence of jets upon collision. This thesis presents the results of an experimental investigation of oblique collision between two fluid jets. The transition from bouncing to coalescence of jets is examined for various jet sizes and angles. Results indicate that the transition from bouncing to coalescence can be rationalized in terms of critical value of the dimensionless parameter Normal Weber Number, which represents the ratio between inertial and surface tension forces. A parametric study of the characteristic of bouncing jets, conducted by varying the nozzle diameter, jet velocity, angle of inclination and fluid viscosity reveals the scaling laws for the quantities involved such as contact time. These scaling laws help us in elucidating the role of various physical forces at play such as viscous stresses, capillary force and inertia / Master of Science

Na corrida humana, a demanda metabólica aumenta com o efeito da fadiga. A menor contribuição da energia elástica das unidades músculo-tendíneas, responsáveis pela propulsão, poderia explicar este fenômeno. O presente estudo analisou os efeitos da fadiga sobre parâmetros do bouncing elástico e sobre as assimetrias contato despregue assim como as implicações da mesma sobre o trabalho mecânico total em diferentes velocidades de corrida. Quatorze participantes corredores recreacionais (8 homens e 6 mulheres) correram em uma faixa de velocidades entre 9 e 14 km.h-1 antes e depois de realizar 60 segundos de saltos verticais máximos (protocolo de fadiga). As corridas foram registradas com uma câmera de vídeo e uma plataforma de força. O processamento dos dados foi realizado utilizando um programa elaborado em Labview versão 8.5. Para determinar os efeitos da fadiga e da velocidade foi utilizado teste ANOVA dois fatores. A mecânica da corrida com o efeito da fadiga apresentou diferenças significativas (p<0,05) tais como: menor trabalho mecânico externo e menor potência mecânica durante trabalho positivo. Esta redução pode ser atribuída à maior rigidez vertical presente na corrida com fadiga, o que diminui a deformação do corpo como um todo prejudicando o armazenamento de energia elástica. A redução da contribuição de energia elástica para o trabalho externo foi de 8%. Porém, as estratégias que determinam a escolha da frequência de passo na corrida, tanto para baixas quanto para velocidades intermediárias de corrida, foram preservadas com o efeito da fadiga. A assimetria contato despregue acentuou-se com fadiga devido à diminuição da fase de elevação balística do CM o que também explica o menor tempo aéreo com fadiga. Conclui-se que o mecanismo elástico da corrida foi prejudicado pela fadiga. / The metabolic cost of human running is increased in fatigued situation. The lower contribution of elastic energy from muscle-tendon units responsible for propulsion could be an explanation for this phenomenon. The main purpose of this study was to analyze the effects of fatigue on parameters of the elastic bouncing, landing take-off asymmetries and their implications for total mechanical work at different running speeds. Fourteen recreational runners (8 men and 6 women) ran at speeds ranging from 9 to 14 km.h-1 before and after a jumping test during 60 s (fatigue protocol). The runs were registered with a video camera and a force platform. A custom-built program, designed in Labview 8.5, was created to analyze the model parameters in the two situations. To determine the effects of fatigue a two-way ANOVA was used. The following differences in running mechanics were statistically significant (p<0.05): lower external mechanical work and mechanical power during push time. These reductions can be ascribed to greater vertical stiffness in the fatigued state, which reduces the whole body deformation impairing the elastic energy storage. However, factors that determine the choice of step frequency, both for low and intermediate running speeds were preserved on fatigued running. The landing take-off asymmetries were accentuated with fatigue due to decreased ballistic lift phase in which also explains the lower aereal time. In conclusion, the impairments on elastic mechanism and consequent adjusts on mechanics were caused by fatigued state in human running.

Na corrida humana, a demanda metabólica aumenta com o efeito da fadiga. A menor contribuição da energia elástica das unidades músculo-tendíneas, responsáveis pela propulsão, poderia explicar este fenômeno. O presente estudo analisou os efeitos da fadiga sobre parâmetros do bouncing elástico e sobre as assimetrias contato despregue assim como as implicações da mesma sobre o trabalho mecânico total em diferentes velocidades de corrida. Quatorze participantes corredores recreacionais (8 homens e 6 mulheres) correram em uma faixa de velocidades entre 9 e 14 km.h-1 antes e depois de realizar 60 segundos de saltos verticais máximos (protocolo de fadiga). As corridas foram registradas com uma câmera de vídeo e uma plataforma de força. O processamento dos dados foi realizado utilizando um programa elaborado em Labview versão 8.5. Para determinar os efeitos da fadiga e da velocidade foi utilizado teste ANOVA dois fatores. A mecânica da corrida com o efeito da fadiga apresentou diferenças significativas (p<0,05) tais como: menor trabalho mecânico externo e menor potência mecânica durante trabalho positivo. Esta redução pode ser atribuída à maior rigidez vertical presente na corrida com fadiga, o que diminui a deformação do corpo como um todo prejudicando o armazenamento de energia elástica. A redução da contribuição de energia elástica para o trabalho externo foi de 8%. Porém, as estratégias que determinam a escolha da frequência de passo na corrida, tanto para baixas quanto para velocidades intermediárias de corrida, foram preservadas com o efeito da fadiga. A assimetria contato despregue acentuou-se com fadiga devido à diminuição da fase de elevação balística do CM o que também explica o menor tempo aéreo com fadiga. Conclui-se que o mecanismo elástico da corrida foi prejudicado pela fadiga. / The metabolic cost of human running is increased in fatigued situation. The lower contribution of elastic energy from muscle-tendon units responsible for propulsion could be an explanation for this phenomenon. The main purpose of this study was to analyze the effects of fatigue on parameters of the elastic bouncing, landing take-off asymmetries and their implications for total mechanical work at different running speeds. Fourteen recreational runners (8 men and 6 women) ran at speeds ranging from 9 to 14 km.h-1 before and after a jumping test during 60 s (fatigue protocol). The runs were registered with a video camera and a force platform. A custom-built program, designed in Labview 8.5, was created to analyze the model parameters in the two situations. To determine the effects of fatigue a two-way ANOVA was used. The following differences in running mechanics were statistically significant (p<0.05): lower external mechanical work and mechanical power during push time. These reductions can be ascribed to greater vertical stiffness in the fatigued state, which reduces the whole body deformation impairing the elastic energy storage. However, factors that determine the choice of step frequency, both for low and intermediate running speeds were preserved on fatigued running. The landing take-off asymmetries were accentuated with fatigue due to decreased ballistic lift phase in which also explains the lower aereal time. In conclusion, the impairments on elastic mechanism and consequent adjusts on mechanics were caused by fatigued state in human running.

L'opération de précipitation oxalique du plutonium dans les usines de retraitement du combustible nucléaire est délicate à mettre en œuvre en raison de la nature collante du précipité. Dans l'idée de pallier ce problème gênant vis à vis d'une production industrielle, le Laboratoire de génie chimique et d'instrumentation du CEA Marcoule propose de réaliser cette opération en colonne pulsée à garnissage. Le précipité est alors confiné à l’intérieur des gouttes de l’émulsion et suffisamment loin des surfaces de l'appareil.Cependant si les surfaces en contact son en acier inoxydable, l'appareil s'encrasse invariablement. La thèse s'insère alors dans une démarche de compréhension fine de ces mécanismes d'encrassement. Bien que les travaux réalisés balayent l'ensemble du problème posé, la thèse est essentiellement centrée sur l’analyse du rebond des gouttes de l’émulsion avec les parois de l'appareil. Les résultats acquis permettent d’enrichir la base de données de la littérature dans une configuration peu usitée tout en ciblant les paramètres clés de ce type d'interaction. Les résultats montrent qu'utiliser en première approche, une colonne pulsée non optimisée et conçue intégralement en acier inox ne peut convenir pour réaliser l'opération de précipitation de radionucléides. Cette précipitation peut cependant être menée en s'orientant vers une technologie différente et brevetée à l'issue de cette thèse. Ce dernier point doit cependant être nuancé car l'exploration à des débits industriels de production n'est pas encore acquise. D'un autre coté, cela peut constituer un enjeu intéressant de génie des procédés. / The process dedicated to the oxalic precipitation of plutonium is very sensitive to the high sticking behavior of the produced precipitates. Therefore, the laboratory of génie chimique et instrumentation based in Marcoule in France puts forward the idea of carrying out the process in a pulsed column. In this way, the precipitates is confined inside in the droplets of the emulsion, far from the surfaces of the apparatus. Nevertheless if those surfaces are made of stainless steal the fouling of the column is inevitably observed. The thesis also introduces the concept and tools dedicated to a fine understanding of the fouling issue. Though the work carried out scans the whole issue, the thesis mainly focuses on drop bouncing. the results provide experimental data in a low-studied configuration and target the key parameters driving th bounce. The application of the these results point out that using an unoptimized stainless steal pulsed column for the precipitation of radionucleides does not prevent from the fouling. The process could still be carried out using another technology patented during the PhD. This last poitn needs more investigations. Especially, the CEA has work on the scale-up steps to design an apparatus wich could be able to porcess industrial flow rates. Bsides ths might be an interessing issue in process engineering.

Na corrida humana, a demanda metabólica aumenta com o efeito da fadiga. A menor contribuição da energia elástica das unidades músculo-tendíneas, responsáveis pela propulsão, poderia explicar este fenômeno. O presente estudo analisou os efeitos da fadiga sobre parâmetros do bouncing elástico e sobre as assimetrias contato despregue assim como as implicações da mesma sobre o trabalho mecânico total em diferentes velocidades de corrida. Quatorze participantes corredores recreacionais (8 homens e 6 mulheres) correram em uma faixa de velocidades entre 9 e 14 km.h-1 antes e depois de realizar 60 segundos de saltos verticais máximos (protocolo de fadiga). As corridas foram registradas com uma câmera de vídeo e uma plataforma de força. O processamento dos dados foi realizado utilizando um programa elaborado em Labview versão 8.5. Para determinar os efeitos da fadiga e da velocidade foi utilizado teste ANOVA dois fatores. A mecânica da corrida com o efeito da fadiga apresentou diferenças significativas (p<0,05) tais como: menor trabalho mecânico externo e menor potência mecânica durante trabalho positivo. Esta redução pode ser atribuída à maior rigidez vertical presente na corrida com fadiga, o que diminui a deformação do corpo como um todo prejudicando o armazenamento de energia elástica. A redução da contribuição de energia elástica para o trabalho externo foi de 8%. Porém, as estratégias que determinam a escolha da frequência de passo na corrida, tanto para baixas quanto para velocidades intermediárias de corrida, foram preservadas com o efeito da fadiga. A assimetria contato despregue acentuou-se com fadiga devido à diminuição da fase de elevação balística do CM o que também explica o menor tempo aéreo com fadiga. Conclui-se que o mecanismo elástico da corrida foi prejudicado pela fadiga. / The metabolic cost of human running is increased in fatigued situation. The lower contribution of elastic energy from muscle-tendon units responsible for propulsion could be an explanation for this phenomenon. The main purpose of this study was to analyze the effects of fatigue on parameters of the elastic bouncing, landing take-off asymmetries and their implications for total mechanical work at different running speeds. Fourteen recreational runners (8 men and 6 women) ran at speeds ranging from 9 to 14 km.h-1 before and after a jumping test during 60 s (fatigue protocol). The runs were registered with a video camera and a force platform. A custom-built program, designed in Labview 8.5, was created to analyze the model parameters in the two situations. To determine the effects of fatigue a two-way ANOVA was used. The following differences in running mechanics were statistically significant (p<0.05): lower external mechanical work and mechanical power during push time. These reductions can be ascribed to greater vertical stiffness in the fatigued state, which reduces the whole body deformation impairing the elastic energy storage. However, factors that determine the choice of step frequency, both for low and intermediate running speeds were preserved on fatigued running. The landing take-off asymmetries were accentuated with fatigue due to decreased ballistic lift phase in which also explains the lower aereal time. In conclusion, the impairments on elastic mechanism and consequent adjusts on mechanics were caused by fatigued state in human running.