Ryerson University

About: Ryerson University is a education organization based out in Toronto, Ontario, Canada. It is known for research contribution in the topics: Computer science & Population. The organization has 7671 authors who have published 20164 publications receiving 394976 citations. The organization is also known as: Ryerson Polytechnical Institute & Ryerson Institute of Technology.

Quantifying and recognizing human movement patterns from monocular video Images-part I: a new framework for modeling human motion

Abstract: Research into tracking and recognizing human movement has so far been mostly limited to gait or frontal posing. Part I of this paper presents a continuous human movement recognition (CHMR) framework which forms a basis for the general biometric analysis of continuous human motion as demonstrated through tracking and recognition of hundreds of skills from gait to twisting saltos. Part II of this paper presents CHMR applications to the biometric authentication of gait, anthropometric data, human activities, and movement disorders. In Part I of this paper, a novel three-dimensional color clone-body-model is dynamically sized and texture mapped to each person for more robust tracking of both edges and textured regions. Tracking is further stabilized by estimating the joint angles for the next frame using a forward smoothing particle filter with the search space optimized by utilizing feedback from the CHMR system. A new paradigm defines an alphabet of dynemes, units of full-body movement skills, to enable recognition of diverse skills. Using multiple hidden Markov models, the CHMR system attempts to infer the human movement skill that could have produced the observed sequence of dynemes. The novel clone-body-model and dyneme paradigm presented in this paper enable the CHMR system to track and recognize hundreds of full-body movement skills, thus laying the basis for effective biometric authentication associated with full-body motion and body proportions.

A Low-Cost Rectifier Topology for Variable-Speed High-Power PMSG Wind Turbines

Abstract: A novel rectifier topology consisting of two three-phase diode bridges and three thyristors is proposed in the paper for variable-speed high-power permanent-magnet synchronous generator (PMSG) wind energy conversion systems (WECSs). The proposed rectifier has several prominent features such as low cost, low power loss, and simple control. Its ability to cascade the input voltages allows it to properly regulate generator speed even when the wind velocity drops to half of the rated value. Consequently, maximum power-point-tracking algorithms can be applied to optimize power capture in a wide range of wind velocities. The operating principle of the rectifier is elaborated. Its use and control in the WECS is presented. The converter and control are verified by simulation and experimental results.

Output Power Control for Variable-Speed Variable-Pitch Wind Generation Systems

Abstract: A robust pitch control strategy for the output power control of wind generator systems in wide-wind-speed range is presented in this paper. The corresponding controller is designed, which consists of a nominal inverse-system controller and a robust compensator. The advantages of the proposed strategy include the simple implementation, tolerance of turbine parameter or some nonparametric uncertainties, and robust control of the generator output power with wind-speed variations. Theoretical analyses, simulation, and experimental results show that the proposed controller can work better in a wide-wind-speed range compared with the traditional proportional-integral-derivative controller. It has similar performance with the neural network controller, but less complexity. Additionally, it can be easily adapted to other wind generator systems.

Lap shear strength and fatigue life of friction stir spot welded AZ31 magnesium and 5754 aluminum alloys

Abstract: Lightweighting is today considered as one of the key strategies in reducing fuel consumption and anthropogenic greenhouse gas emissions. The structural applications of lightweight magnesium and aluminum alloys in the transportation industry inevitably involve welding and joining while guaranteeing the safety and reliability of motor vehicles. This study was aimed at evaluating lap shear strength and fatigue properties of friction stir spot welded (FSSWed) AZ31B-H24 Mg and 5754-O Al alloys in three combinations, i.e., similar Mg-to-Mg, Al-to-Al, and dissimilar Al-to-Mg joints. The Mg/Mg similar weld had a nugget-shaped stir zone (SZ) around the keyhole where fine recrytallized equiaxed grains were observed. While the hardness profile of the Mg/Mg similar weld exhibited a W-shaped appearance, the lower hardness values appeared in the TMAZ and HAZ of both Mg/Mg and Al/Al similar welds. In the Al/Mg dissimilar weld, a characteristic interfacial layer consisting of intermetallic compounds (IMC) Al 12 Mg 17 and Al 3 Mg 2 was observed. Both Mg/Mg and Al/Al similar welds had significantly higher lap shear strength, failure energy and fatigue life than the Al/Mg dissimilar weld. While the Al/Al weld displayed a slightly lower lap shear strength than the Mg/Mg weld, the Al/Al weld had higher failure energy and fatigue life. Three types of failure modes were observed. In the Mg/Mg and Al/Al similar welds, at higher cyclic loads nugget pullout failure occurred due to fatigue crack propagation circumferentially around the nugget, while at lower cyclic loads fatigue failure occurred perpendicular to the loading direction caused by the opening of keyhole through crack initiation in the TMAZ and HAZ. In the Al/Mg dissimilar weld nugget debonding failure mode was observed because of the presence of an interfacial IMC layer.