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.

A Multi-Purpose Balanced Transformer for Railway Traction Applications

Abstract: A multi-purpose balanced (MPB) transformer is proposed in this paper for electric railway applications. The MPB transformer is developed from impedance-matching (IM) transformers widely used in China's railway systems. The proposed MPB transformer has three main functions: (1) it provides a symmetrical two-phase voltage of 27.5 kV for railway overhead lines to power electric trains; (2) it supplies a three-phase balanced voltage of 10.5 kV for railway substations; and (3) it can accommodate a three-phase harmonic filter with improved power factor and reduced manufacturing cost. In this paper, the operating principles of the MPB transformer are elaborated, the design of the harmonic filters is discussed, and the results of computer simulations are provided. A 16-MVA MPB transformer was designed and commissioned, and real-time field measurements are provided.

Evolution of cooperation on temporal networks.

Abstract: Population structure is a key determinant in fostering cooperation among naturally self-interested individuals in microbial populations, social insect groups, and human societies. Traditional research has focused on static structures, and yet most real interactions are finite in duration and changing in time, forming a temporal network. This raises the question of whether cooperation can emerge and persist despite an intrinsically fragmented population structure. Here we develop a framework to study the evolution of cooperation on temporal networks. Surprisingly, we find that network temporality actually enhances the evolution of cooperation relative to comparable static networks, despite the fact that bursty interaction patterns generally impede cooperation. We resolve this tension by proposing a measure to quantify the amount of temporality in a network, revealing an intermediate level that maximally boosts cooperation. Our results open a new avenue for investigating the evolution of cooperation and other emergent behaviours in more realistic structured populations. Population structure enables emergence of cooperation among individuals, but the impact of the dynamic nature of real interaction networks is not understood. Here, the authors study the evolution of cooperation on temporal networks and find that temporality enhances the evolution of cooperation.

Investigations Into the Control and Protection of an Existing Distribution Network to Operate as a Microgrid: A Case Study

Abstract: With the increasing attention to the concept of microgrids, it has become important to identify the requirements that enable an electric distribution network to operate as a microgrid. This paper studies a realistic distribution network to accomplish the following: 1) determine the conditions under which the network can operate as a microgrid and 2) present the control scenarios that allow the islanded operation of the network. In particular, the employment of electronically coupled distributed energy resources with the fault-ride-through and synchronization capabilities is investigated. Another objective of this paper is to propose practical protection strategies that are effective in both operational modes of a microgrid (i.e., the grid-connected mode and the islanded mode), considering the system constraints; the protection strategies provide the microgrid with acceptable reliability against different fault scenarios. The effectiveness of the control and protection strategies is demonstrated and discussed through a comprehensive set of simulation studies conducted in the PSCAD/EMTDC software environment.