Ryerson University

About: Ryerson University is a education organization based out in Toronto, Ontario, Canada. It is known for research contribution in the topics: Population & Poison control. 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.

Monitoring Gene Expression in Mixed Microbial Communities by Using DNA Microarrays

Abstract: A DNA microarray to monitor the expression of bacterial metabolic genes within mixed microbial communities was designed and tested. Total RNA was extracted from pure and mixed cultures containing the 2,4-dichlorophenoxyacetic acid (2,4-D)-degrading bacterium Ralstonia eutropha JMP134, and the inducing agent 2,4-D. Induction of the 2,4-D catabolic genes present in this organism was readily detected 4, 7, and 24 h after the addition of 2,4-D. This strain was diluted into a constructed mixed microbial community derived from a laboratory scale sequencing batch reactor. Induction of two of five 2,4-D catabolic genes (tfdA and tfdC) from populations of JMP134 as low as 105 cells/ml was clearly detected against a background of 108 cells/ml. Induction of two others (tfdB and tfdE) was detected from populations of 106 cells/ml in the same background; however, the last gene, tfdF, showed no significant induction due to high variability. In another experiment, the induction of resin acid degradative genes was statistically detectable in sludge-fed pulp mill effluent exposed to dehydroabietic acid in batch experiments. We conclude that microarrays will be useful tools for the detection of bacterial gene expression in wastewaters and other complex systems.

Active Damping for PMSG-Based WECS With DC-Link Current Estimation

Abstract: An active-damping strategy is proposed for the suppression of speed and torsional oscillations in permanent-magnet synchronous generator (PMSG)-based wind-energy conversion systems (WECSs). Direct-driven configuration with PMSG is an attractive choice for WECS because of the gearbox elimination and cost reduction due to small pole-pitch design. However, speed and torsional oscillations appear when the generator is directly connected to the wind turbine without any assistant damping device. Based on small-signal analysis, a low-bandwidth design for the power or generator torque controller of PMSG can help to reduce the oscillation amplitude, but the system dynamic performance is thus sacrificed. From the power-flow's point of view, the oscillation is reflected in the dc-link current. With the help of switch function modeling based on the space-vector-modulation scheme, the average dc-link current can be estimated and applied to the compensation strategy, which provides positive damping resulting in stability improvement. The simulation and experiment results verify the theoretical analysis and the validation of the proposed strategy.

Framing sustainability as a property of software quality

Abstract: This framework addresses the environmental dimension of software performance, as applied here by a paper mill and a car-sharing service.

Comparison of Basic Visual Servoing Methods

Abstract: In this paper, comparison of the position-based and image-based robot visual servoing methods is investigated, with an emphasis on the system stability, robustness, sensitivity, and dynamic performance in the Cartesian and image spaces. A common comparison framework using both predefined and taught references is defined in the context of the sensory task space robot control approach. The camera, target, and robot modeling errors in the system are considered in the comparison. Both methods are shown to be locally asymptotically stable and locally robust with respect to modeling errors. While the two methods are shown to be comparable and sensitive to the camera and target modeling errors when using predefined references, they are insensitive to these errors when using taught references. However, the system Cartesian and image trajectories and time-to-converge are affected by the camera, target, and robot modeling errors regardless of the type of references. Finally, other fundamental characteristics of the two methods including sensory task space singularity and local minima, motion coupling, and implementation issues are also compared. The comparison results are verified in simulations.