• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 1430
  • 660
  • 168
  • 113
  • 41
  • 28
  • 21
  • 17
  • 16
  • 14
  • 14
  • 13
  • 12
  • 12
  • 12
  • Tagged with
  • 3114
  • 774
  • 648
  • 412
  • 392
  • 256
  • 226
  • 220
  • 216
  • 215
  • 210
  • 203
  • 187
  • 173
  • 163
  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.

The mechanical properties of normal and pathological bone

Dickenson, R. P. January 1978 (has links)
No description available.

Sensor-Based Assessment of the Quality of Human Motion During Therapeutic Exercise

Taylor, Portia E. 01 December 2012 (has links)
Advances in technology and research have been employed in recent years to develop efficient mechanisms to deliver home-based exercise therapy to patients suffering from knee osteoarthritis, a degenerative disease associated with aging. Essential to the success of a therapeutic home-exercise program is the quality of the motion performed by the patient. The unsupervised nature of home-based exercise may lead to incorrect exercise performance by patients; however, current home-based exercise programs do not provide mechanisms for monitoring the quality of motion performed or for providing feedback to the patient. This lack of support has been found to be a factor in patient non-compliance to home exercise programs. Our goal is to provide a motion sensor-based system that can evaluate the quality of exercise to support home rehabilitation. We introduce the Quality Assessment Framework (QAF) that uses low-cost motion sensors with data processing and machine learning techniques to assess the quality of human motion performed during therapeutic exercises. Data from fifteen persons with knee osteoarthritis were collected in a laboratory environment, and a classifier was trained using multi-label learning methods to detect descriptive characteristics of the patient's motion. These characteristics represent errors in the exercise performance as well as variables, such as speed, that are regularly monitored by the patient's therapist. Results from multi-label learning are presented and recommendations are made on requirements for an in-home therapeutic exercise system. A classifier, using Ensembles of Classifier Chains with a Support Vector Machine base classifier, provides the best method for assessing human motion quality in the QAF. Leave-one-out and leave-half-out testing provided us with information on the achievable level of generalizability for new patients whose motion is not contained in the training set. We found that a small amount of new patient data is required for good recognition of characteristics in exercise performances. The QAF can be adapted to the home therapy needs of conditions other than knee OA. We present a preliminary design of the InForm Exercise System that utilizes the QAF and has the potential to present feedback to patients completing home exercise programs.

Relative changes of the biomechanical properties of living rabbit brain tested under controlled physiologic conditions with stress-relaxation indentation

Kazina, Colin John 16 January 2014 (has links)
Mechanical testing of living brain with control or measurement of all potential sources of variability is difficult and not often or consistently performed. The primary objective of the current work is to compare mechanical properties of the living rabbit brain across relatively high and low groupings of arterial blood partial pressure of carbon dioxide (pCO2) and mean arterial pressure (MAP), with control or measurement of all deformation, anatomical, and other physiological variables. It is hypothesized that there are significant differences in relative viscoelastic properties of the living rabbit brain under different combinations of pCO2 and blood pressure. Stress-relaxation brain indentations were performed on seven consecutive anesthetized living rabbits, with control or measurement of all possible variables.. Five indentations were performed on each animal, with 15 minute periods of rest between each indentation, with the following relative physiological parameters: Indentation 1. Low MAP and low pCO2. Indentation 2. High MAP and low pCO2. Indentation 3. Low MAP and high pCO2. Indentation 4. High MAP and high pCO2. Indentation 5. Low MAP and low pCO2. The data were fitted to a generalized Maxwell model that incorporated two viscoelastic terms and one equilibrium elastic term. The relative stress-relaxation coefficients and material properties were determined, and compared using statistical analysis. Peak stresses encountered with relative step-loading ranged from approximately 2-4 x 103 Pa, with corresponding “instantaneous” elastic moduli approximating 4-8 x 103 Pa. A short and long Time of Relaxation was determined for each viscoelastic term of the model, and ranged from 0.03 – 1.72 s and 9.92 – 32.55 s respectively. Comparison of stress-relaxation coefficients and material properties reveals statistically significant differences in the stress coefficients and their respective elastic moduli across different combinations of pCO2 and MAP, and between the last indentation group and previous indentations. There were no significant differences found in Time of Relaxation coefficients. In conclusion, mechanical properties of step-loaded living rabbit brain are relatively dependent on pCO2 and MAP, and repetitive deformations. This may be important for further understanding of the brain in different physiological states and accurate mechanical characterization of the brain. It also highlights the need to control for these parameters during the mechanical testing of brain.

A biomechanical comparison of the long snap to punter between high school and university level football players

Chizewski, Michael George 06 November 2009 (has links)
The study compared the kinematics used to perform fast and accurate long snaps in high school (HS) and university level (UNI) athletes. The study also determined the kinematic variables related to greater release velocity and which variables are significant predictors of release velocity or total snap time* (TST) for HS, UNI, and both groups combined*. Ten HS and ten UNI subjects were recruited. The athletes were filmed with eighty-three variables measured using Dartfish TeamPro 4.5.2 software. UNI athletes had significantly greater release velocity (15.15m/s) and left elbow extension velocity (752 deg/sec) than the HS group (13.21m/s and 498 deg/sec). TST had the strongest correlation to release velocity in HS (r=-0.915) and UNI snappers (r=-0.918). HS long snappers may benefit from less elbow flexion and more knee flexion in the set position. UNI long snappers may benefit from increased left elbow extension ROM and decreased shoulder flexion at release.

To investigate the economic impact and to propose an engineering solution for the lack of a hip prosthesis manufacturing industry in Greece

Skittides, Philimon January 1998 (has links)
No description available.

Static asymmetrical whole body exertion in humans

Wilkinson, Alexis Tracey January 1995 (has links)
The asymmetrical postures of subjects were recorded simultaneously with the force applied by one hand on a handle at three heights during exertion in specific directions, including many with a left or right directional component. A biomechanical analysis of the exertions was made in the horizontal plane and in the vertical plane containing the force vector. Analysis in the vertical plane showed that subjects achieved greater forces by both increased muscular effort and more effective deployment of body weight. Analysis in the horizontal plane revealed the existence of a horizontal moment at the foot-base. This moment was found to be small or negligible when a person exerted in the fore-aft plane, but was of considerable magnitude when exertion was carried out in directions with a lateral component. To investigate the generation of this moment, two further experiments were conducted. The first used surface electromyography to explore the roles of the flexors and extensors of the lower limb, while the second utilized a force plate to examine in detail the forces and moments at the foot-base. It was found that for laterally directed exertions, approximately half of the moment was generated by one foot exerting a force on the floor in a direction opposite to the other, and half was produced by each foot exerting a horizontal torque individually. The quadriceps, hamstrings and tibialis anterior were implicated in the first mechanism. The horizontal turning moment at the feet has not previously been recognised and should be incorporated into models of asymmetrical exertion.

Techniques used by elite javelin throwers to achieve high release speeds

Morriss, Calvin James January 2002 (has links)
No description available.

Optimisation of performance in running jumps

Wilson, Cassie January 2003 (has links)
Running jumps such as the high jump and the long jump involve complex movements of the human body. The factors affecting performance include approach conditions, strength of the athlete and the muscle activation timings at each joint. In order to investigate the mechanics of jumping performances and the effect of these factors, an eight-segment, subject specific, torque-driven computer simulation model of running jumps was developed, evaluated and used to optimise performances of jumps for height and distance. Wobbling masses within the shank, thigh and trunk segments, and the ground-foot interface were modelled as non-linear spring-damper systems. The values for the stiffness and damping constants were determined through optimisation. The inertia data were obtained from anthropometric measurements on the subject using the inertia model of Yeadon (1990b). Joint torques predicted by the simulation model were expressed as a function of angular velocity and angle using data collected from an isovelocity dynamometer. The simulation model was evaluated by comparing the actual performances with simulations using kinematic and kinetic data collected. Movement of the wobbling masses was found to be in the region of 40 mm in the shank and thigh and 90 mm in the trunk. This movement resulted in a lower, more realistic initial peak in the ground reaction force. Co-contraction was found to occur at the joints during impact in order to increase the initial level of eccentric activation and also the rise time to maximum eccentric activation. Differences of 2% and 1% in the height and distance achieved were obtained between actual performances and simulations. An optimisation procedure was used to maximise the height reached and distance travelled by the mass centre, in simulations of jumps for height and distance respectively, by varying the torque generator activation time histories at each joint. An increase of 12% in the height reached by the mass centre in the jump for height and 14% in the distance reached by the mass centre in the jump for distance were achieved.

The role of series elasticity and biarticular muscles in lower extremity movements. A study of muscle mechanics using an EMG-to-force model

Barrett, R. Unknown Date (has links)
No description available.

Hydrodynamics of the human body during the freestyle tumble turn /

Lyttle, Andrew. January 1999 (has links)
Thesis (Ph.D.)--University of Western Australia, 2000.

Page generated in 0.0764 seconds