Thesis (M.S.)--University of Wisconsin--Madison. / Typescript. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves 103-109).

Material from J.K. Davis' Thesis (Ph. D.)--University of Michigan, 1941. / Reprinted from the Journal of physical chemistry, vol. 45, no. 8, Nobvember, 1941.

Thesis (doctoral)--Lund University, 1982. / Includes bibliography.

Thesis (Ph. D.)--Columbia University, 1917. / Vita.

Thesis (Ph. D.)--University of Chicago, 1934. / Lithoprinted. "Private edition, distributed by the University of Chicago libraries, Chicago, Illinois."

Thesis (Ph. D.)--University of Wisconsin--Madison, 1980. / Typescript. Vita. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves 102-106).

Si les effets délétères de la fatigue neuromusculaire au cours de mouvements simples ne sont plus à démontrer, les effets d’une telle modalité de fatigue au cours de tâches complexes, i.e., poly-articulaires, restent à investiguer. Par ailleurs, il a été démontré que la fatigue mentale pouvait également impacter négativement la performance sportive au cours d’exercices mono-articulaires ou énergétiques. L’objectif de ce travail de thèse visait donc à évaluer l’impact de ces deux modalités de fatigue (mentale et neuromusculaire) sur des paramètres physiologiques (temps de réaction) et techniques (vitesse et précision des balles) associés au tennis de table, ceci afin de mieux comprendre la nature et l’ampleur des altérations pour, in fine, proposer des situations concrètes pour les entraîneurs et/ou préparateurs physiques. Au cours des six études qui composent ce travail de thèse, nous avons évalué la demande de l’activité du joueur en tennis de table au niveau des membres inférieurs (étude préliminaire et étude 1). Par la suite, les études 2 et 3 se sont intéressées aux effets de la fatigue (neuromusculaire et mentale) sur les caractéristiques de la balle. Des altérations différentes ont été mises en évidence selon la nature de la fatigue considérée. Enfin, les études 5 et 6 ont mesuré les effets de ces mêmes modalités de fatigue sur les différentes composantes du temps de réaction. Ces études ont montré que des participants soumis à une tâche mentalement ou physiquement fatigante étaient capables de maintenir un temps de réaction stable. Cependant, les mécanismes permettant ce maintien du niveau de performance étaient différents selon la nature de la fatigue considérée. / The deleterious effects of neuromuscular fatigue during simple movements are well documented. However, the effects of neuromuscular fatigue during complex tasks, i.e., polyarticular movements, are still a matter of debate. Otherwise, it has been demonstrated that mental fatigue could also have a negative impact on sport performance during monoarticular or energetic exercises. This thesis aimed to investigate the effects of both mental and neuromuscular fatigue on physiological (reaction time) and technical (speed and accuracy of the ball) parameters associated to table tennis, in order to propose practical applications for trainers and physical coaches to optimize the performance. This thesis was composed of six studies. In the first two studies, the characterisation of the effort involving the lower limbs during table tennis was performed (preliminary study and study 1). Thereafter, studies 2 and 3 focused on the effects of both mental and neuromuscular fatigue on ball characteristics. The results of these studies showed that mental and neuromuscular fatigue induced alterations of ball characteristics, but these alterations could differ between both fatigue conditions. Lastly, studies 4 and 5 measured the effects of these two types of fatigue on reaction time components. These studies highlighted that when they are mentally or physically fatigued, participants were able to maintain their level of performance. However, the mechanisms to maintain the performance level were different depending on the type of fatigue considered.

The Rayleigh-Taylor instability of a water-air interface was investigated using electrical and photographic methods. An apparatus is described which accelerates a rectangular tank of water downwards and produces reproducible instabilities from a pure sinusoidal standing surface water wave of known phase and amplitude. The electrical measurements revealed that in addition to the bulk motion, films of water are produced on the walls of the water tank. The existence of these and other features of the instability are substantiated by photographs of the various instabilities that were produced. The electrical measurements led to a new scaling law for the phenomenon of climbing fluid films at accelerations greater than gravity. Several linear devices were also developed for measuring the amplitudes of surface water waves. / Science, Faculty of / Physics and Astronomy, Department of / Graduate

The first part of this thesis is concerned with theoretical and experimental investigations of step discontinuities on a planar surface waveguide. An approximate theoretical solution to the unbounded discontinuity problem is obtained by bounding the open structure with perfect conductors, since there is a direct relationship between the mode spectra of the two configurations. Mode-matching is used to solve the bounded case. The method is "tested" on four discontinuity configurations considered by other workers. Good agreement with the previous results is obtained in all cases except one for which the original results are shown to be inaccurate. The experimental investigation is carried out on a dielectric coated conductor surface waveguide, supporting the first TM mode, at a frequency of 30 GHz. Standing wave measurements are obtained using a X/2 dipole oriented along the longitudinal component of electric field. The parameters of interest are the magnitude and the phase of the reflection coefficient. The experimental results confirm those obtained theoretically. The theoretical and experimental techniques are later applied in an investigation of a cascaded step discontinuity configuration. The theoretical approach involves the use of wave transmission matrices. Experimental results for the magnitude of the reflection coefficient are found to be in reasonable agreement with theory. The second part of this work describes a theoretical and experimental study of dielectric waveguides, of circular cross-sections, perturbed by axial slots. In particular, the normalized propagation coefficient of the dominant modes with each polarization is determined analytically using a standard perturbation technique and experimentally using an open resonant cavity. The perturbation results give quite a good indication of the trends observed experimentally. It is found that there is an optimum size of the perturbation which gives the maximum separation between the normalized propagation coefficients of the two polarizations. / Applied Science, Faculty of / Electrical and Computer Engineering, Department of / Graduate

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