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.

Predictive Control of a Three-Level Boost Converter and an NPC Inverter for High-Power PMSG-Based Medium Voltage Wind Energy Conversion Systems

Abstract: In this paper, a new medium voltage power converter topology using a diode rectifier, three-level boost (TLB) converter, and neutral-point-clamped (NPC) inverter is proposed for a high-power permanent magnet synchronous generator-based wind energy conversion system. The generator-side TLB converter performs the maximum power point tracking and balancing of dc-link capacitor voltages, while the grid-side NPC inverter regulates the net dc-bus voltage and reactive power to the grid. A significant improvement in the grid power quality is accomplished as the NPC inverter no longer controls the dc-link neutral point voltage. A model predictive strategy is proposed to control the complete system where the discrete-time models of the proposed power electronic converters are used to predict the future behavior of control variables. These predictions are evaluated using two independent cost functions, and the switching states which minimize these cost functions are selected and applied to the generator- and grid-side converters directly. In order to comply with the high-power application, the switching frequencies of the TLB converter and NPC inverter are minimized and maintained below 1.5 and 1 kHz, respectively. The proposed topology and control strategy are verified through MATLAB simulations on a 3-MW/3000-V/577-A system and dSPACE DS1103-based experiments on 3.6-kW/208-V/10-A prototype.

A critical review on inhibition of dark biohydrogen fermentation

Abstract: Dark fermentation of organic wastes for hydrogen gas (H2) production is an attractive strategy of being renewable and carbon neutral However, various toxic or inhibitory compounds can significantly limit sustainable operation and widespread adoption of this biotechnology The metabolism of fermentative microbes in dark fermentation system can be inhibited by excess substrate, micronutrients, macronutrients, metal ions, high temperature, acidic pH, un-dissociated organic acids, competitive microbes, and substrate-derived toxic substances This review paper introduces these potential inhibitory compounds, inhibition mechanisms, and provides engineering perspectives on the control of inhibition

A Probabilistic Method for Image Enhancement With Simultaneous Illumination and Reflectance Estimation

Abstract: In this paper, a new probabilistic method for image enhancement is presented based on a simultaneous estimation of illumination and reflectance in the linear domain We show that the linear domain model can better represent prior information for better estimation of reflectance and illumination than the logarithmic domain A maximum a posteriori (MAP) formulation is employed with priors of both illumination and reflectance To estimate illumination and reflectance effectively, an alternating direction method of multipliers is adopted to solve the MAP problem The experimental results show the satisfactory performance of the proposed method to obtain reflectance and illumination with visually pleasing enhanced results and a promising convergence rate Compared with other testing methods, the proposed method yields comparable or better results on both subjective and objective assessments

Exploration of the Breakdown Phenomenon in Freeway Traffic

Abstract: Of late, there has been a considerable volume of empirical research on freeway operations during periods of high flow. Part of the motivation for this realm of research is the attractive possibility of increasing flow and speed by preventing breakdown in congested operations. This possibility has been fueled by observations of a "capacity drop," wherein the discharge flow from the resulting queue is smaller than those observed before breakdown. The research on which this paper is based was aimed at exploring in more detail the implications of metering traffic flow at levels below that at which a breakdown occurs. From this perspective, the nature of precongestion flows is investigated empirically to determine the potential gains from such a policy. The most important contribution is an examination of the likelihood of success of such metering by establishing the probability of breakdown at various traffic flow levels. It is shown, for example, that 1-min median lane flows that are 20 percent larger than q...

Current-Source Converter and Cycloconverter Topologies for Industrial Medium-Voltage Drives

Abstract: This paper, along with an earlier published paper as Part 1, provides a comprehensive review of the state of the art of high-power converters (above 1 MW) for adjustable-speed ac drives. In this highly active area, different converter topologies have been developed for various drive applications in the industry. Due to its extensive coverage, the subject is divided into two parts: multilevel voltage source and current source converter topologies. This paper is focused on the second part and covers the current source converter technologies, including pulsewidth-modulated current-source inverters (CSIs) and load-commutated inverters. In addition, this paper also addresses the present status of the direct converter, which is also known as cycloconverter (CCV). This paper focuses on the latest CSI and CCV technologies and an overview of the commonly used modulation schemes. It also provides the latest technological advances and future trends in CSI- and CCV-fed large drives. This paper serves as a useful reference for academic researchers and practicing engineers in the field of power converters and adjustable-speed drives.