Made available in DSpace on 2014-06-11T19:31:11Z (GMT). No. of bitstreams: 0 Previous issue date: 2010-04-30Bitstream added on 2014-06-13T19:41:08Z : No. of bitstreams: 1 gomide_lmw_dr_jabo.pdf: 1262197 bytes, checksum: 39214ac3ccd56d8d651f7b418a642da7 (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / Este trabalho avaliou, por meio da cinematografia, as alterações biomecânicas induzidas após elevação em seis graus da pinça ou do talão no casco dos membros torácicos em equinos ao trote e se tais alterações eram influenciadas pelo material da ferradura. Para isso, foram utilizados seis equinos adultos PSA sadios, sem evidências clínicas de alterações locomotoras. Os animais foram separados em dois grupos: grupo 1, que utilizou ferraduras confeccionadas em ferro, e grupo 2, que utilizou ferraduras em alumínio. O experimento foi realizado em três semanas. Na semana basal os animais foram ferrados com ferradura plana. Nas semanas seguintes houve elevação em seis graus da pinça ou do talão. Os animais realizaram três sessões de exercícios em esteira rolante por semana, utilizando dois marcadores esféricos reflexivos nas faces dorsal e lateral do casco do membro torácico esquerdo. As variáveis cinemáticas avaliadas na terceira sessão de cada semana foram: duração da passada, tempo de apoio, tempo de suspensão, altura e comprimento da passada, além da avaliação do movimento descrito pelo casco. A análise estatística foi feita por meio do teste t-Student. As alterações decorrentes da elevação da pinça ou do talão foram muito diferentes, algumas vezes opostas, entre os animais para o mesmo tipo de elevação, inclusive dentro do mesmo grupo. Conclui-se que as alterações na angulação do casco induziram mudanças no andamento, mas, com base nos resultados deste trabalho, não é possível determinar uma indicação clínica geral para cada alteração imposta ou material utilizado / This study investigated, using kinematics methods, biomechanical changes due to toe or heel elevation in equine forelimb at trot and if it can be influenced by shoe material. Six adult sound arabian horses were separated in two groups: iron and aluminum group. The study was performed in three weeks with three treadmill exercise sessions each. Reflexive markers were applied on dorsal and lateral surfaces of left forelimb hoof. In first week horses were shod with flat shoes. In the following weeks horses were shod with six degrees toe or heel elevation. Measured kinematic variables were stride duration, stance fase, swing fase, maximal displacement in vertical direction of the hoof, stride length and flight arc. Statistical analisys used t-Student test. Variations caused by toe or heel elevation were extremely different, even opposite, between animals to same elevation type, even in same group. Results showed that response due to investigated elevations were different for each animal. We concluded that different hoof angulations induced changes in movement but the results of this investigation do not provide basis for general clinical applications for each elevation or material used

abstract: When manufacturing large or complex parts, often a rough operation such as casting is used to create the majority of the part geometry. Due to the highly variable nature of the casting process, for mechanical components that require precision surfaces for functionality or assembly with others, some of the important features are machined to specification. Depending on the relative locations of as-cast to-be-machined features and the amount of material at each, the part may be positioned or ‘set up’ on a fixture in a configuration that will ensure that the pre-specified machining operations will successfully clean up the rough surfaces and produce a part that conforms to any assigned tolerances. For a particular part whose features incur excessive deviation in the casting process, it may be that no setup would yield an acceptable final part. The proposed Setup-Map (S-Map) describes the positions and orientations of a part that will allow for it to be successfully machined, and will be able to determine if a particular part cannot be made to specification. The Setup Map is a point space in six dimensions where each of the six orthogonal coordinates corresponds to one of the rigid-body displacements in three dimensional space: three rotations and three translations. Any point within the boundaries of the Setup-Map (S-Map) corresponds to a small displacement of the part that satisfies the condition that each feature will lie within its associated tolerance zone after machining. The process for creating the S-Map involves the representation of constraints imposed by the tolerances in simple coordinate systems for each to-be-machined feature. Constraints are then transformed to a single coordinate system where the intersection reveals the common allowable ‘setup’ points. Should an intersection of the six-dimensional constraints exist, an optimization scheme is used to choose a single setup that gives the best chance for machining to be completed successfully. Should no intersection exist, the particular part cannot be machined to specification or must be re-worked with weld metal added to specific locations. / Dissertation/Thesis / Masters Thesis Engineering 2016

Thesis (PhD (Education))--University of Stellenbosch, 1998. / This dissertation deals with typical, widespread student errors with respect to kinematic graphs as revealed by a literature survey, as well as an own empirical investigation into the nature and extent of these misconceptions. The fact that certain misconceptions turned out to be more widespread than initially believed, has serious consequences for educators' assumptions about students' understanding of graphs in general, as well as their ideas on how to minimise some generally occurring "alternative views on graphs". Students' graphing skills are analysed and described in terms of a number of translations between various representations of physical events involving motion. A special focus is placed on graph transformations, which are translations from one graphical representation to another. It turned out that this provides valuable information about a learner's graphing skills, as well as his understanding of the relevant kinematic quantities and conventions required to make successful transformations.

As robotic manipulators become more prevalent, particularly in hazardous environments or for repetitive tasks, demand continues for increased performance and decreased cost. In some applications, both can be achieved by reducing the weight of the manipulator. However, reduced weight often leads to significant structural flexibility and vibration which, for most tasks, is generally regarded as detrimental to performance. Although there has been a great deal of research in the area of controlling flexible manipulators to follow a desired trajectory, much less work has been directed towards choosing the trajectory itself. The objective of this work is to optimize point-to-point motions in joint space to reduce vibration. This problem is formulated as one of functional optimization and the applicable methods of solution are reviewed. An indirect method is chosen that allows modular software development by preserving the integrity of existing nonlinear dynamics models. Numerical results are compared with trajectories generated by other means and show a significant reduction in vibration possible by optimization, particularly for varying joint paths. Finally, the effectiveness of the trajectory optimization scheme is further evaluated for high-speed, large-angle motions of an experimental nonplanar two-link flexible manipulator. Such results are lacking in the literature, but are very important for assessing the utility of trajectory optimization in the presence of modelling and tracking errors. Again, significant reductions in vibration are demonstrated by using the global optimization approach for trajectory generation. / Graduate

We explore the evolution of the internal gas kinematics of star-forming galaxies from the peak of cosmic star formation at z similar to 2 to today. Measurements of galaxy rotation velocity V-rot, which quantify ordered motions, and gas velocity dispersion sigma(g), which quantify disordered motions, are adopted from the DEEP2 and SIGMA surveys. This sample covers a continuous baseline in redshift over 0.1 < z < 2.5, spanning 10 Gyr. At low redshift, nearly all sufficiently massive star-forming galaxies are rotationally supported (V-rot > sigma(g)). By z = 2, 50% and 70% of galaxies are rotationally supported at low (10(9)-10(10) M-circle dot) and high (10(10)-10(11) M-circle dot) stellar mass, respectively. For V-rot > 3 sigma(g), the percentage drops below 35% for all masses. From z = 2 to now, galaxies exhibit remarkably smooth kinematic evolution on average. All galaxies tend toward rotational support with time, and higher-mass systems reach it earlier. This is largely due to a mass-independent decline in sigma(g) by a factor of 3 since z - 2. Over the same time period, V-rot increases by a factor of 1.5 in low-mass systems but does not evolve at high mass. These trends in V-rot and sigma(g) are at a fixed stellar mass and therefore should not be interpreted as evolutionary tracks for galaxy populations. When populations are linked in time via abundance matching, sigma(g) declines as before and V-rot strongly increases with time for all galaxy populations, enhancing the evolution in V-rot sigma(g). These results indicate that z = 2 is a period of disk assembly, during which strong rotational support is only just beginning to emerge.

Surgery to correct cam femoroacetabular impingement (FAI) is increasingly popular. Despite this, no known study has used motion analysis and ground reaction forces to quantify the outcome of surgery for FAI. The goal of this study was to compare the preoperative and postoperative lower-extremity joint kinematic and kinetic measurements of cam FAI patients during activities of daily living with use of a high-speed motion capture system and force platforms. We hypothesized that the lower-extremity joint mechanics of FAI patients during level walking and maximal squatting would resemble more those of healthy control subjects, after surgery. Ten patients with unilateral symptomatic cam FAI, who underwent corrective surgery using an open or combined technique, performed walking and maximal depth squatting trials preoperatively and postoperatively. Thirteen healthy control subjects, matched for age, sex and body mass index, provided normative data. Results showed that postoperatively, FAI patients had reduced hip ROM in the frontal and sagittal planes, produced smaller peak hip abduction and external rotation moments, and generated less peak hip power compared to the control group during level walking. During maximal squatting, postoperative FAI patients squatted to a greater depth, and had larger knee flexion and ankle dorsiflexion angles, as well as the sum of all joint angles of the affected limb at maximal depth compared to the preoperative values. The lower-extremity joint and pelvic mechanics of FAI patients did not fully return to normal after surgery. Although surgery seemed to reduce hip pain and restore a normal femoral head-neck offset, it further impaired muscle function as a result of muscle incisions. More research is needed to determine the effects of muscle incisions, which could help improve surgical techniques and develop better rehabilitation programs for FAI patients.

The purpose of this study was to examine the effects of body mass and sex on the joint biomechanics of the lower extremity during stair ascent and descent. Nineteen normal weight (8M and11F; BMI: 22.1 ± 1.8 kg/m2), 18 overweight (14M and 4F; BMI: 27.4 ± 1.3 kg/m2) and 8 obese subjects (3M and 5F; BMI: 33.3 ± 2.5 kg/m2) were recruited. Joint mechanical loading presented by joint moment of force and peak joint angles at the hip, knee, and ankle during stair climbing were recorded and analyzed using a motion analysis system with 10 cameras and 4 force plates. The MANOVA and linear regression analysis found a significantly larger knee extensor moment (p=0.026) among the overweight compared to the normal weight participants during descent. Sex differences were found in the peak joint angles, as the females abducted their knees more than the males (p=0.002; r(51) = 0.51) during descent.

Running has been a popular sport because of convenience and health benefits. Fatigue among recreational runners may alter running mechanics, thereby increasing the risk for injury. The purpose of this study was to evaluate changes in lower extremity biomechanics throughout a 3.1 mile (5K) run. Ten male and ten female participants wore reflective markers to capture contralateral pelvic drop, knee adduction, knee abduction, and hip adduction. Participants ran 3.1 miles (5K) on a treadmill at a self-determined pace. A two-way, repeated measures ANOVA was conducted to capture the within-subject data across time and between-subject comparing differences in gender. Females had significantly greater contralateral pelvic drop but it did not change over time. Knee abduction angles significantly declined over the five observations. Gender differences and effects of distance can alter the biomechanics in recreational runners. More research is needed to identify predisposing factors to the development of chronic running injuries. / North Dakota State University. Department of Health, Nutrition, and Exercise Sciences

>Magister Scientiae - MSc / In this study a complete set of exclusive (~p; 2p) polarization transfer observables of closed-shell oxygen isotopes are calculated using both direct and inverse kinematics using the relativistic plane wave impulse approximation. The interaction matrix is written in terms of the SPVAT (scalar, pseudoscalar, vector axial vector, tensor) covariants where each amplitude is obtained directly from experimental phase shifts. A relativistic mean eld theory approximation is used to compute boundstate wave functions of the nucleons. We study the evolution of polarization transfer observables within oxygen isotopes and identify observables which may discriminate between these isotopes. The same kinematical conditions are considered for both direct and inverse kinematics: the incident energy is set at 504 MeV and coplanar angles are xed at (22:12 ;􀀀40:30 ). The results indicate that only three spin observables, namely, Ay, P and Dnn distinguish di erent oxygen isotopes at these kinematical conditions in the inverse kinematics.

No description available.