Thesis (M.S.)--University of Wisconsin--Madison, 1967. / eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references.

Thesis (M.S.)--University of Wisconsin--Madison, 1967. / eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references.

Thesis (Ph. D.)--University of Wisconsin, 1966. / Typescript. Vita. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references.

Thesis (MSc)--Stellenbosch University, 2002. / ENGLISH ABSTRACT: We use Hanbury-Brown Twiss interferometry to determine Bose-Einstein correlations in the transverse and longitudinal directions. By using these two directions, we are able to determine the shape of the pion emitting source. The analysis is done with the UA1 (1985) data for pp collisions at Vs = 630 GeV. Two frames of reference, namely the laboratory frame and the Longitudinal Center-of-Mass System (LCMS) are used. A fit to a two-dimensional Gaussian parametrization yields good results. In the laboratory frame, an oblate form of the source is observed, with the value of the transverse radius (rt) larger than the longitudinal (rL) one. The LCMS analysis finds a prolate form of the source (rt < rL). A few reasons are discussed for the difference in the shape between the different reference frames. Our results are also compared with other hadron-hadron and e+ e: experiments. / AFRIKAANSE OPSOMMING: Hanbury-Brown Twiss interferometrie was gebruik om Bose-Einstein korrelasies in die transversale en longitudinale rigtings te bepaal. Deur hierdie twee rigtings te gebruik, kan die vorm van die pion-bron bepaal word. Die UA1 (1985) datastel van die pp botsings by Vs = 630 GeV is gebruik om die analise uit te voer. Twee verwysingstelsels, naamlik die laboratorium stelsel en die Longitudinale Massamiddelpunt-stelsel is aangewend. 'n Passing met 'n twee-dimensionele Gaussiese parametrisering het goeie resultate opgelewer. In die laboratorium stelsel, is 'n ovaalvormige vorm vir die bron waargeneem, met die transversale radius (rt) groter as die longitudinale radius (rl)' Die Longitudinale Massamiddelpunt stelsel het 'n prolate vorm vir die bron voorspel, met rt < ri, 'n Paar redes vir die verskil in die vorm van die pion-bron vir die verskillende verwysingstelsels word bespreek. Ons resultate word ook met ander hadron-hadron en e+e- eksperimente vergelyk.

This research studies the electrical power reduction and control analysis of various motion tasks of a humanoid robot. These motions include standing up and sitting down. Each motion’s tasks have their stable and unstable phases throughout the complete motion cycle. Unstable phases can be caused by gravity forces and improper handling of the upper body of the humanoid robot leaning too forward or backward. Even though most of the dynamic motions seem to be accomplished very simply by humans; standing up and sitting down could create challenges for humanoid robots. Some of the critical challenges researches face are: dynamic nature of motions, humanoid robot joint coordination, whole body balance, stability of the model, limited energy source, energy saving techniques and modeling. Dynamic motions of humanoid robots can be modeled and analyzed to reduce electrical power use. In order to accomplish such energy savings, a researcher needs to study the kinematics, dynamics of a humanoid, and motion tasks with given constraints. The robot in this research is modeled as a planar humanoid robot. All motion tasks of a humanoid robot are characterized in terms of motion variables. These motion variables include joint angular positions, joint angular velocity, joint angular acceleration, humanoid robot center of mass (CoM) position, velocity and acceleration change and center of pressure (CoP) position change. All mathematical models are completed so that electrical power analysis of each task produce comparable results. Humanoid robot joint cost functions related to energy consumption are used to define joint input electrical power used, joint mechanical power used, joint mechanical power dispersion and joint power loss due to torque required. In this research, a 4-link 3-joint humanoid is modeled for standing up and sitting down tasks. For each task, kinematics and dynamics models are created, motion constraints are found, energy and power usage analysis for whole robot and for individual joint motors are accomplished. By finding the best energy usage per motion variable, humanoid robot used less input electrical power to accomplish the motion task.

No description available.

No description available.

Hopping is considered a mass-spring model movement in which the leg supports the center of mass. There is a preferred hopping frequency and hopping outside of that frequency is more difficult and requires more energy. Leg stiffness has been shown to be an important factor when hopping at different frequencies in young adult populations. The purpose of this study was to observe how a still-developing preadolescent population would modify leg stiffness while hopping at different frequencies and if they have similar motor control strategies compared to young adults. The subjects hopped on their dominant leg to the beat of a metronome at one of four frequency conditions based on their calculated preferred frequency, MP (preferred frequency), MM (20% increase), MF (40% increase), and MS (20% decrease). It was found that this population could change their hopping frequency and they achieved this by manipulating their leg stiffness. At the higher frequency conditions there was less movement of the toe and the center of mass in both the vertical and horizontal directions, including decreased hopping height, decreased COM displacement and COM range of motion. Preadolescents demonstrated an adult-like ability to increase leg stiffness and modulate movement of the toe and the COM while adapting to a range of hopping frequencies. This ability could translate into other mass-spring model movements such as running and jumping.

Orientador: Tamotsu Hirata / Resumo: A natação competitiva tem evoluído a cada ano que passa em vários países do mundo. Exemplos como os Estados Unidos e Austrália estão sendo seguidos em outras partes do planeta. Para chegar no nível elevado de performance é preciso que o esporte tenha como apoio pesquisas elaboradas para o aproveitamento direto entre os treinadores. No Brasil este conceito tem crescido, mas a natação ainda é carente em alguns aspectos, como por exemplo, as pesquisas para avaliação na área biomecânica. Sabe-se que a pesquisa nesta área requer um custo elevado de equipamentos e mão de obra especializada, porém os dados fornecidos são de grande valia para os treinadores e atletas que podem através disso aperfeiçoar sua técnica. Um bom exemplo são as pesquisas feitas com finalidade de corrigir a performance de saída dos nadadores. Neste trabalho é proposto um sistema de análise cinemática e dinâmica da performance de saída com base na cinemetria em que o centro de massa é calculado a cada momento no gesto de saída. Através desse método foram verificados os dados de Tempo de Bloco, Tempo de Vôo, Tempo Submerso, Tempo Complementar, Tempo Total de saída (15m), Ângulo de Abandono do bloco, Ângulo de Entrada na água, Velocidade Vertical e Horizontal de abandono do bloco, Velocidade Vertical e Horizontal de entrada na água, o Pico de Força de Inércia Horizontal e a Força de Inércia Horizontal no abandono. Os resultados foram considerados válidos neste trabalho e coerentes com os pesquisados na literatura, tornando o sistema de medição proposto adequado para futuras pesquisas. / Abstract: The competitive swimming has developed every year around the world. Samples with the United State and Australia were being following in others parts of planet. For to reach in high level of performance is need that the sports has with aid research developed to the direct progress between coachs. In Brazil this concept has growed, but the swimming still is deficient in some aspects with the researchs for biomechanics avaliation.The research in this area need expensive equipments and especialist professional, however the statistcs datas are the most important to coachs and athletics to improve your thecnique. The good example are research with the objective to improve the performance of swimmer's starts. In this work is propose the analysis kinematics and dynamics of start in swimming based in cinemetry that the center of mass is calculated every moment in start movement. Through this method was verified the block time data, flight time, underwater time, complementar time, total time of start (15m), block leave angle, entry angle, vertical and horizontal speed of block leave, vertical and horizontal speed of entry, top horizontal inertia force and the horizontal inertial force in leave. The results were considered valid in this work and coherent with researched, becoming the propose meter system adequate to future researchs. / Mestre

Stair climbing is a common activity encountered in daily living. Stair ascent is a demanding task that requires a large range of motion of the joints, strong muscle strength, good cardiovascular fitness, and fine balance control. Given this, the activity can be difficult for different populations that lack muscle strength and coordination. To train and assist people in this activity, several robotic platforms have been proposed, but these limit the natural motion of the individual. For example, these devices fix the placement of the feet and reduce the natural swing of the lower limbs. This makes it difficult to manipulate the center of mass, which is crucial to stair ascent. In this dissertation, we present a novel parallel cable-driven platform in which the end effector is the user’s pelvis; the stairmill tethered pelvic assist device. This architecture allows the user to retain their natural movement and relation between the feet and the center of mass, all while applying three dimensional forces on the pelvis during continuous stair ascent on a revolving stairmill. In this work, we show the design, fabrication, and validation of this robotic system. Various force strategies were explored during stairmill ascent using this robotic platform. A characterization experiment was conducted to investigate gait performance and muscle coordination. Two simple interventions were tested to show the potential for long-term training program. This work sheds light on the different strategies of stair climbing and how we can use cable driven platforms to train and assist individuals during this challenging task. The knowledge gained by this work allows for the expansion of designing training paradigms for stair climbing with natural motion. These can assist individuals in improving their quality of life.