Thesis (Ph. D.)--University of Wisconsin--Madison, 1981. / Typescript. Vita. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves 166-172).

Thesis (Ph. D.)--University of Wisconsin--Madison, 1983. / Typescript. Vita. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves 153-160).

Thesis (M.S.)--University of Wisconsin--Madison, 1968. / eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references.

Thesis (M. S.)--University of North Carolina at Greensboro, 2006. / Title from PDF title page screen. Advisor: Randy Schmitz ; submitted to the School of Health and Human Performance. Includes bibliographical references (p. 96-100)

M.Tech.

The functional loss of knee stabilitv that results from soft tissue and ligamentous injury is a serious problem for the conpetitive athlete. Non-surgical attempts to restore femoro-tibial stability and function have been centered on the external application of supportive tape and athletic knee braces. Several athletic braces are available on the market today. The more substantial ones, however, have proven ajrtibersane and uncomfortable in their attempts to provide support for the unstable knee. Prototype I of tlie rotational, convex, poly-axial, mechanical knee brace (Taylor Brace) was subjected to testing to deteririine its effect on knee stability and dynamic range of motion. Electrogoniometric recordings of knee function in three mutually perpendicular movement parameters were obtained from each subject at varying speeds of ambulation. Testing was conducted in the laboratory for unbraced and braced conditions using a 2 x 2 collapsible parallelogram chain electrogoniometer. Instant center of rotation pathways and joint surface velocity angles were determined from roentgenogram analysis of the unstable knee for unbraced and braced conditions. Seven medial roentgenograms were taken of the knee with the femur fixed and the tibia moved from ninety degrees of flexion to zero degrees of flexion in increments of fifteen to twenty degrees. Stress analysis was carried out on the unstable knee using a mechanical stress machine. Regulated forces were anplied to the knee joint and radiographic changes in the range of medial and anterior laxity recorded for the unbraced and braced knee. Subjective evaluation was also conducted in which subjects evaluated the Taylor Brace verbally, after each session of activity, and in an overall written assessement at the end of the study. Various aspects of brace construction and function were discussed under pre-determined criteria. Electrogoniometric results showed that the Taylor Brace had a general restraining effect on unwanted internal-external rotation and varus-valgus movement of the knee. Reductions in the flexion-extens range were also recorded but were considered unimportant as a hindrance to total knee function. There was also an indication that the contra-lateral, unbraced knee pattern changed following bracing. There were no consistent trends in the pattern or disoersion of the instant center of rotation pathways following bracing. A consistent shifting posteriorly and superiorly of the individual centers and a change in abnormal joint surface velocity angles, however, was noted following application of the Taylor Brace. Subjective evaluation suggested several minor aspects of brace construction for improvement in future prototypes. Triigh cuff rigidity, tibial abraison and brace slippage were cited as areas for improvement. Knee joint range and articulation was considered excellent as well as ease of application, overall brace comfort, lightness and cosmetics of design. / Education, Faculty of / Curriculum and Pedagogy (EDCP), Department of / Graduate

Les cellules solaires à base de CuIn1-xGaxSe2 sont des dispositifs en couches minces permettant d’atteindre des hauts rendements de conversion photovoltaïque. Le CuIn1-xGaxSe2 est un absorbeur permettant d’adapter l’énergie de la bande interdite de la cellule solaire en changeant la teneur en Ga. Le rendement record de conversion photovoltaïque actuel a été obtenu pour x~0.3, alors que la théorie indique qu’il devrait être obtenu pour un x~0.7. L’origine de cette limite pour x élevé reste en débat. Dans cette thèse, on étudie deux origines liées aux interfaces internes de CuIn1-xGaxSe2 à savoir i) le changement d’élément ségrégé aux joints de grains pour des fortes et faibles teneurs en Ga et ii) la ségrégation défavorable du séléniure du cuivre au volume ou à la surface. Dans une première partie, une étude par premiers principes (DFT) montre que la ségrégation substitutionnelle de l’In par Ga (ou de Ga par In) n’est pas favorisée dans un joint de macle. Dans le cas plus général d’une surface notre étude sur les forces motrices de ségrégation montre qu’il est plus facile de faire ségréger une impureté d’In qui se trouve dans une matrice de CuGaSe2 que l’inverse. Dans la seconde partie, les résultats expérimentaux du CuIn1-xGaxSe2 indiquent qu’en augmentant le taux de Ga la couche devient plus inhomogène. Cela est dû aux inhomogénéités locales de concentration en Cu dans la couche. L’origine de ce phénomène est liée à la cinétique de la formation de CuGaSe2 qui est lente et à la faible diffusion du Cu et du Ga. Nous proposons une étape de relaxation supplémentaire pendant la co-évaporation de CuIn1-xGaxSe2 qui permet de faciliter la croissance des grains, d’améliorer l’homogénéité de la couche et d’atteindre l’équilibre attendu. / Amongst the different semiconductor materials used as absorber layers, polycrystalline CuIn1-xGaxSe2 is one of the most promising materials in the thin-film photovoltaic technology. Due to the high efficiency, stability and band gap tunability with x, thin-film solar cells based on CuIn1-xGaxSe2 absorber layer are already industrially implemented. Moreover, in the multi-junction solar cell technology the aim of reaching higher efficiencies while keeping the fabrication costs low, makes the wide band gap indium-free CuGaSe2 absorber layer an interesting candidate as a top cell in a hybrid tandem solar cell based on c-Si bottom cell. However, the actual energy conversion efficiency strongly decreases for x larger than 0.3 and it does not follow the theoretical predictions indicating better performances for x around 0.7. The difficulty to obtain a high device performance for large x has been a worldwide question for several years and many theories have been proposed to explain the limited conversion efficiency. A possible cause of the limited CuIn1-xGaxSe2 performance for large x involves the local inhomogeneities at the inter- or intra-grain regions, since the nature of the accumulated species or compound at the interfaces can be detrimental or beneficial for the solar cell efficiency. In this thesis we investigate two possible phenomena that are likely to occur at the CIGSe interfaces i) a preferential elemental segregation at the grain boundaries and ii) the detrimental copper selenide surface segregation or bulk precipitation. In this work, the elemental segregation is investigated at equilibrium by coupling ab initio calculations and thermodynamic modeling. Our results indicate that substitutional (InGa or GaIn antisite) cannot be expected in the most frequently present interfaces such as the twin grain boundaries. A complementary and simple analysis of the main segregation driving forces was also studied in order to understand the segregation in the more general cases, such as the surface segregation. Our calculations show that In is slightly more favorable to segregate at the surface rather than Ga. The experimental analysis on CuIn1-xGaxSe2 films at intermediate and large x reveals that increasing x the Cu content in the CuIn1-xGaxSe2 film can locally differ, creating detrimental Cu-enriched domains within the bulk of the film. This phenomenon is due to the slow kinetics at large x and the reduced Cu and Ga interdiffusion. In this work, we propose a strategy to avoid these local inhomogeneities by applying a relaxation stage during the CuIn1-xGaxSe2 deposition process. This stage improves the photovoltaic performance, since it leads to a long-range equilibration, grain growth, annihilation of voids and a close to stoichiometry bulk which was expected

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Thesis (Ph. D.)--Ohio State University, 2003. / Title from first page of PDF file. Document formatted into pages; contains xvi, 255 p.; also includes graphics (some col.). Includes abstract and vita. Advisor: Glenn S. Daehn, Dept. of Materials Science and Engineering. Includes bibliographical references (p. 201-202).

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