This study examined perspectives of the trip to/from school and travel mode choice among parents who differed in socio-economic status (SES), and whose children attended schools located in different areas (i.e., urban vs. inner-suburban) across Toronto. Thirty-seven parents (20 active and 17 non-active travelers) of grade four to six students from four elementary schools (capturing diversity with respect to built environment and SES) participated in qualitative interviews after taking photos of their trip to/from school. Data were analyzed using thematic analysis linking the text and visual data. School travel was a habitual behaviour involving a 2-step parental decision-making process; these decisions were influenced by different factors. While escort decisions were dictated by safety concerns, the behavioural cost and reinforcing value of travel mode alternatives dictated mode choice. Strategies addressing these behavioural cost and reinforcing value factors may be helpful in making walking to/from school the quickest and most convenient choice.

No description available.

Whole-body vibration is an important problem facing operators of off-road vehicles. Research has shown that operators exposed to low-frequency whole-body vibration can experience temporary and even permanent injuries. One solution to this problem is to develop an active seat capable of canceling the vibrations felt by the operator. Several passive, semi-active, active, and fully active seats have been designed and built to address this problem. Furthermore, controllers have been developed to optimize the seat performance. Vibration cancellation seating systems seem to be a promising and practical way to reduce the effects of whole-body vibration. To extend developments in this area, a Hyper-Active seat has been designed and built at the Georgia Institute of Technology. The seat utilizes a 3 Revolute-Prismatic-Revolute (RPR) parallel manipulator design which allows for the independent control of the vertical, horizontal and pitch angle directions. The seat is powered using three hydraulic actuators which are controlled using MATLAB's Simulink, xPC Target, and Real-Time Workshop. Controllers were developed to control the position of the seat, as well as cancel unwanted vibration. To test the performance of the Hyper-Active seat, the system identification of the seat was undertaken using open-loop forcing functions. The seat was evaluated in each degree of freedom to understand the potential of the seat to cancel harmful vibration. In addition to reducing harmful vibrations, the seat can double as a safety seat to reduce injuries during a frontal collision. If the front edge of the seat bottom can be raised very quickly, then the forward motion of the passenger can be reduced during a crash. An optimal method for performing this motion is developed.

A low speed wind tunnel experimental investigation was conducted to determine the effectiveness of the leading edge pulsed blowing and the trailing edge jet blowing/ Gurney flap on the improvement of aerodynamic performance of an unmanned aerial vehicle at low Reynolds numbers. The wind tunnel tests for the leading edge pulsed jet blowing were conducted at 10%, 30% and 50% location of the chord length from the leading edge at a free stream velocity of 20 m/s. The jet momentum coefficient and the non-dimensional pulser frequency had been varied independently to investigate the effectiveness of the leading edge pulsed blowing. The trailing edge jet blowing tests were conducted at free stream velocity of 20 m/s at different jet momentum coefficients. The leading edge pulsed blowing showed a strong dependency of the actuator effectiveness on the jet momentum and the pulser frequency. The leading edge pulsed blowing had delayed the flow separation over the airfoil from an angle of attack of 17° to 22° with a docile stall for jet emanating at 10% location of the chord length for a jet momentum coefficient of 0.0275. The pulsed blowing at 50% chord location generated higher lift compared to the 10% location of the pulser with an abrupt stall at 19°. There was no evidence of the lift augmentation in the pre-stall angle of attack regime. The experimental results showed that the trailing edge jet flap was capable of generating significant roll moment at realistic jet momentum coefficients. The fluidic actuators were then integrated into the wings of a scale Extra 330 model airplane. The wind tunnel results for the leading edge pulsed blowing on the scale model indicated a delay in the stall of the airplane from an angle of attack of 12° to 21° with a 13% increase in the lift at take-off and landing speed of 17 m/s. The trailing edge jet actuators were also able to augment lift and demonstrate the roll control authority at low angle attacks at a cruising speed of 30 m/s.

No description available.

A thermodynamics-based constitutive model is derived which predicts the nonlinear strain and magnetization response that magnetic shape memory alloys (MSMAs) exhibit when subjected to mechanical and magnetic loads. The model development is conducted on the basis of an extended thermo-magneto-mechanical framework. A novel free energy function for MSMAs is proposed, from which the constitutive equations are derived in a thermodynamically-consistent manner. The nonlinear and hysteretic nature of the macroscopic material behavior is captured through the evolution of internal state variables which are motivated by the crystallographic and magnetic microstructures of MSMAs. Model predictions are presented for different relevant loading cases and analyzed in detail. Finally, magnetostatic boundary value problems for MSMAs are considered and numerically solved using the finite element method. For these computations the developed constitutive model provides the nonlinear magnetic properties of the MSMA. The knowledge of the magnetic field distribution in the computational domain as a function of the applied field, which results from this magnetostatic analysis, is useful for the proper interpretation of experimental results as well as the design of experiments and applications.

The design, fabrication, and testing of a quarter-car facility coupled with various control algorithms are presented in this thesis. An experimental linear tubular motor, capable of producing a 52-N force, provides control actuation to the model. Controllers consisting of two designs were implemented: a classical controller employing lead and lag networks and a state-space feedback design. Each design was extensively simulated to screen for receptiveness to actuation force limitations and robustness regarding the inexact tire modeling. The goal of each controller was to minimize the acceleration of the sprung mass in the presence of simulated road disturbances, modeled by both sinusoidal and step input excitation wheels. Different reference velocity inputs were applied to the control scheme. Responses to a zero reference were juxtaposed to those that resulted from tracking a reference built off a model that incorporated inertial-frame damping attached to the sprung mass. The outcome of this comparison was that low-frequency disturbances were attenuated better when tracking a zero reference, but the reference relaxation introduced by the inertialframe damping model allowed for better-attenuated high frequency signals. Employing an inertial-frame damping value of 250 N-s/m, the rejected frequency component of the system response synchronous with the disturbance input excitation of 40 rad/s bettered by 33% and 28% when feeding control force from the classical controller and state-space controller, respectively. The experimental analysis conducted on the classical and state-space controllers produced sinusoidal disturbance rejection of at worst 50% within their respective bandwidths. At 25 rad/s, the classical controller was able to remove 80% of the base component synchronous with the disturbance excitation frequency, while the state-space controller filtered out nearly 60%. Analysis on the system's ability to reject step disturbances was greatly confounded with the destructive lateral loading transferred during the excitation process. As a result, subjection to excitation could only occur up to 25 rad/s. At the 20 rad/s response synchronous to the disturbance excitation, the classical and state-space controllers removed 85% and 70% of the disturbance, respectively. Sharp spikes in timebased amplitude were present due to the binding that ensued during testing.

Euclidean distance transformation is a fundamental technique in image understanding and computer vision. Some important characteristics in image analysis such as skeleton and object boundary are based upon the distance transformation computation. In this thesis, we compare our method of computing Euclidean distance transformations with the method of Chamfer distance transformation. Our method is faster and more accurate than the Chamfer method. The boundary detection is an interesting and challenging task in computer vision. We integrate distance transform, watershed transform and active contour model to achieve boundary detection. Our method can successfully separate the touching objects, so as to facilitate the subsequent image processing for obtaining the geometric, and texture characteristics of objects. These features are useful for further medical images applications.

Thesis (M.S. in environmental engineering)--Washington State University, December 2009. / Title from PDF title page (viewed on Jan. 15, 2010). "Department of Civil and Environmental Engineering." Includes bibliographical references (p. 32-34).

Thesis (MA)--University of Montana, 2009. / Contents viewed on December 11, 2009. Title from author supplied metadata. Includes bibliographical references.