Thesis (Ph. D.)--Worcester Polytechnic Institute. / Keywords: parachute shedding characteristics; near wake evolution; parachute inflation; canopy breathing; velocity field measurements. Includes bibliographical references (p. 126-131).

Thesis (M. Phil.)--University of Hong Kong, 2001. / Includes bibliographical references (leaves 223-235).

Up to 85% of cyclists experience repetitive strain injuries (RSI's). During long bouts of repetitive tasks, muscle fatigue may cause mal-alignments in kinematics, having cumulative effects, leading to an RSI. Purpose: The study's purpose was to examine how changes in localized muscle fatigue relate to changes in movement kinematics in highly trained cyclists throughout a full fatigue protocol. Methods: Seven highly trained cyclists participated in a 2 session experiment. Session 1 included a VO2 max test and familiarization trial and Session 2 was the fatigue protocol. Kinematic angles measured were trunk lean, hip, knee, ankle, and knee splay angle. Mean angle (MA) and range of motion (ROM) was calculated for each revolution thought the trial. Muscles monitored were the quadriceps, hamstring, gastrocnemius, and tibialis anterior. EMG median frequency (MDF) for each muscle was calculated for each revolution by averaging MDF for the two halves of each revolution. Cross-correlation analysis was done on MDF and MA data and MDF and ROM data. Results: All subjects exhibited increases in trunk lean and decreases in ankle angle. Non-monotonic changes were observed in trunk lean, ankle, knee splay angle, and among ROM results for all 5 angles. A 1-tailed T-tests for all subjects, revealed that HAM (p = 0.020) and GAS (p = 0.018) exhibited significant muscle fatigue. One-tailed T-tests yielded significantly negative cross-correlation time lags [Greek small letter tau] for trunk lean MA, ROM, and hip MA. Conclusions: Non-monotonic changes are present in kinematics and MDF. Therefore pre vs. post experimental designs cannot quantify fatigue processes. Shifts in trunk lean MA, ROM and hip MA are significantly correlated with preceding decreasing shifts of MDF (indicative of onset of fatigue). / text

Orbit-based modeling is a powerful way to construct dynamical models of galaxies. It has been used to measure the masses of supermassive black holes (SMBHs), constrain dark matter halos, and to recover information about the orbit structure of galaxies. This type of modeling usually goes hand in hand with the study of elliptical galaxies, however its applicability extends much further than this. In this thesis, I apply the well-studied technique of orbit-based modeling to two different types of galaxies—NGC 4594 (Sa) and Fornax (dSph). In NGC 4594, I use orbit-based models to update the mass of the central SMBH, place new constraints on its dark matter halo, and analyze the internal moments of its distribution function. For Fornax, the focus is to determine the shape of the dark matter density profile as well as to learn what we can from the internal moments. / text

The purpose of this thesis was to create a computational wrist model that predicts carpal bone motion in order to investigate the complex kinematics of the human wrist. The tuning of this model was primarily based on in vitro, kinematic measurements of the carpal bones obtained from the same cadaver arm as the geometry for the model was generated. A rigid body spring model of the wrist was built using the kinematic simulation software RecurDynTM 6.1. Surface models of the eight carpal bones, the bases of the five metacarpal bones, and the distal parts of the ulna and radius, all obtained from computed tomography (CT) scans of a cadaver upper limb, were utilized as the geometry for this model. Elastic contact conditions between the rigid bodies modeled the influence of the cartilage layers, and ligamentous structures were constructed using nonlinear, tension-only spring elements. Motion of the wrist was simulated by applying forces to the tendons of the five main wrist muscles modeled. Three wrist motions were simulated: extension, ulnar deviation and radial deviation. The model was mainly tuned by comparing the simulated displacement and orientation of the carpal bones with previously obtained CT-scans of the same cadaver arm in deviated (45 deg ulnar and 15 deg radial), and extended (57 deg) wrist positions. Simulation results for the scaphoid, lunate, capitate, hamate and triquetrum are presented here and provide credible prediction of carpal bone movement. The impact of certain model parameters on simulation results has been investigated by performing sensitivity analyses, and their severity has been documented. The results of the first simulations indicate that this model may assist in future wrist kinematics investigations. However, further optimization and validation are required to define and guarantee the reliability of this model. It is suggested that this rigid body spring model may be part of an interacting framework between in vitro and in vivo investigations, as well as other computational models, in order to improve and complement each biomechanical investigation method. / Thesis (Master, Mechanical and Materials Engineering) -- Queen's University, 2007-08-30 16:30:32.543

Objective As part of this work, two preliminary studies were conducted that identified three possible swings used at the elite level of volleyball and the resulting ball velocities created using these swings. Therefore, the purpose of this work was to explore the kinematic aspects of the different spike attack arm swings (straight ahead (SA), cross body (CB) and outside (OS)) where each different swing was broken down into its constituent parts. Methods Six elite-level varsity players participated in this study. A motion tracking system was used to collect motion data which was used to calculate the kinematics of the upper arm during each of the swing types. A number of minimums and maximums were then calculated including maximum hand speed. To compare means between swings one-way ANOVA’s were used. Results Few differences were found between the swing types. The only difference seen between the SA CB swings was a more pronounced wrist flexion during the CB swing. It is possible that this helped propel the ball across the body during the CB. The OS swings differed from the CB and SA swings in that the OS was less horizontally adducted and there was a more pronounced external rotation during CB than during OS. These differences are likely to be responsible for the ball being hit away from the midline of the body during the OS swing. Typically, the hand speed results agreed with those of the study done previously concerning resulting ball speeds when these swings were employed. Conclusions Between the SA, CB and OS swing types, only the OS was consistantly different throughout the three studies. It is recommended that future studies attempt to examine the whole body during these types of swings. Also, it appears that elite-level players may be quite different kinematically, and each one should be treated as a separate case in a training situation. The findings of these studies may help coaches, trainers and athletes develop better training, injury prevention and rehabilitation programs in the sport. / Thesis (Master, Kinesiology & Health Studies) -- Queen's University, 2008-07-16 12:10:06.42

A new special case computer simulation to model the non-linear, three dimensional dynamic equations of motion of a five degree of freedom point contact joint has been developed and the functionality has been validated with data collected from a physical model. A system physically realistic to model was designed with sphere in sphere contact. A small outboard body articulates within a larger inboard spherical cut out body and springs help provide stability to the system by attaching the outboard body to the ground. The outboard body can move relative to the inboard body in both a rolling and sliding manner. The dynamic equations of motion were determined using Kane’s formulation and a numerical solution was attained through the implementation of a fourth-fifth order, variable time step, Runge-Kutta integrator. The positions of four markers, located on the outboard body of the system, were predicted in ground fixed coordinates by the solution routine. A physical model of the system was constructed and position locations of four markers located on the outboard body were captured by an Optotrak 3020 motion tracking system. Both static and dynamic experimental trials were performed and compared to the simulation. For one test case, the experimental data frequency of oscillation was found to be ωe = 2.33 Hz and the simulation frequency was found to be ωs = 2.37 Hz. Several sources for the discrepancies include viscous damping, a possible additional forcing function caused by lead wire sway, and neglecting the mass of the system’s springs. Coulomb damping was included in the simulation. / Thesis (Master, Mechanical and Materials Engineering) -- Queen's University, 2007-10-30 16:12:57.843

Stair negotiation has been identified by older adults as one of the most challenging locomotor tasks, one that is associated with a high risk for falls and serious injury. Currently lacking is a comprehensive understanding of the lower limb during stair negotiation in an older adult population. It has been identified that more research is needed to determine key determinants of difficulty and safety on stairs. The objective of this thesis was to investigate lower limb kinematics and kinetics during stair negotiation and evaluate the impact of handrail use on stair ambulation in young adults, older adults, and older adults with a fear of falling (FOF). The four studies that make up this dissertation provide a detailed picture of the lower limb joint kinematics and kinetics during stair ambulation, as well as provide insight into the role of handrail use and FOF in performance of stair negotiation. Specifically, in the first study principal component analysis (PCA) was used, of the scores generated from the PCA models four principal component (PC) scores were identified that could be used to correctly classify 95% of young and older adults. The second study provided a comprehensive data set of lower limb joint kinematics and kinetics during stair negotiation. The third study identified comparable centre of pressure velocities (VCOP) between young adults and older adults during stair negotiation with and without a handrail. Whereas older adults with FOF demonstrated reduced VCOP during stair negotiation without a handrail and further reduced VCOP when using the handrail. Furthermore, no significant difference in lower limb moments during stair negotiation with and without a handrail were found in older adults, as was similar for older adults with FOF. However, a gait assessment revealed that older adults with FOF demonstrated differences from ‘normal’ gait patterns during stair negotiation with and without a handrail. These studies provide a comprehensive normative dataset of the lower limb joint kinematics and kinetics during stair negotiation, as well as provide insight into the role of handrail use and fear of falling in performance of stair ambulation. It is important to appreciate the nature and extent of normal age-related adaption and compensatory strategies to identify unique patterns of movement due to the superimposition of pathology. / Thesis (Ph.D, Kinesiology & Health Studies) -- Queen's University, 2010-09-24 14:50:22.242

We examine the globular cluster system (GCS) of the isolated elliptical NGC 720 using the Gemini Multi-Object Spectrograph (GMOS) and have obtained spectra for 241 candidate globular clusters (GCs) extending to a galactocentric radius of 40 kpc. Of the 241 candidates, 120 are confirmed GCs, where 46 are members of the metal-poor, blue, population and 74 are members of the metal-rich, red, population. A (g-i)=0.50 colour split is used to identify the blue and red populations. We measure the full GCS to have a rotational velocity (Vrot) of 50 +/- 7 km/s with a position angle (PA) of 170 +/- 69 degrees. The red population has a Vrot = 97 +/- 14 km/s with PA = 147 +\- 18 degrees and the blue population has a Vrot = 79 +/- 7 km/s with PA = 89 +/- 18 degrees. The full GCS has an average velocity dispersion of 168 +/- 22 km/s, for the red population is 156 +/- 30 km/s and for the blue population is 181 +/- 33 km/s. The velocity dispersion pro file for all populations is constant with increasing radius, suggesting the presence of a dark matter halo. Using a tracer mass estimator, we have measured the mass out to 40 kpc as 1.8(+0.6/-0.1)x10^12 Msun for a potential which traces the dark matter pro file. We also estimate the M/L_V = 30 - 70. This study extends our survey of GCSs to isolated environments. / Thesis (Master, Physics, Engineering Physics and Astronomy) -- Queen's University, 2011-01-31 11:30:54.389

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