Concordia University

About: Concordia University is a education organization based out in Montreal, Quebec, Canada. It is known for research contribution in the topics: Context (language use) & Control theory. The organization has 13565 authors who have published 31084 publications receiving 783525 citations. The organization is also known as: Sir George Williams University & Loyola College, Montreal.

Publishing set-valued data via differential privacy

Abstract: Set-valued data provides enormous opportunities for various data mining tasks. In this paper, we study the problem of publishing set-valued data for data mining tasks under the rigorous differential privacy model. All existing data publishing methods for set-valued data are based on partition-based privacy models, for example k-anonymity, which are vulnerable to privacy attacks based on background knowledge. In contrast, differential privacy provides strong privacy guarantees independent of an adversary's background knowledge and computational power. Existing data publishing approaches for differential privacy, however, are not adequate in terms of both utility and scalability in the context of set-valued data due to its high dimensionality.We demonstrate that set-valued data could be efficiently released under differential privacy with guaranteed utility with the help of context-free taxonomy trees. We propose a probabilistic top-down partitioning algorithm to generate a differentially private release, which scales linearly with the input data size. We also discuss the applicability of our idea to the context of relational data. We prove that our result is (∈, δ)-useful for the class of counting queries, the foundation of many data mining tasks. We show that our approach maintains high utility for counting queries and frequent itemset mining and scales to large datasets through extensive experiments on real-life set-valued datasets.

n-Gram Statistics for Natural Language Understanding and Text Processing

Abstract: n-gram (n = 1 to 5) statistics and other properties of the English language were derived for applications in natural language understanding and text processing. They were computed from a well-known corpus composed of 1 million word samples. Similar properties were also derived from the most frequent 1000 words of three other corpuses. The positional distributions of n-grams obtained in the present study are discussed. Statistical studies on word length and trends of n-gram frequencies versus vocabulary are presented. In addition to a survey of n-gram statistics found in the literature, a collection of n-gram statistics obtained by other researchers is reviewed and compared.

Analysis and design considerations of a load and line independent zero voltage switching full bridge DC/DC converter topology

Abstract: The analysis and design of a zero voltage switching (ZVS) full bridge DC/DC power converter topology is presented in this paper. The converter topology presented here employs an asymmetrical auxiliary circuit consisting of a few passive components. With this auxiliary circuit, the full bridge converter can achieve ZVS independent of line and load conditions. The operating principle of the circuit is demonstrated, and the steady state analysis is performed. Based on the analysis, a criterion for optimal design is given. Experiment and simulation on a 350-400 V to 55 V, 500 W prototype converter operated at 100 kHz verify the design and show an overall efficiency of greater than 97% at full load.

Fiber-wireless (FiWi) access networks: A survey

Abstract: This article provides an up-to-date survey of hybrid fiber-wireless (FiWi) access networks that leverage on the respective strengths of optical and wireless technologies and converge them seamlessly. FiWi networks become rapidly mature and give rise to new powerful access network solutions and paradigms. The survey first overviews the state of the art, enabling technologies and future developments of wireless and optical access networks, respectively, paying particular attention to wireless mesh networks and fiber to the home networks. After briefly reviewing some generic integration approaches of EPON and WiMAX networks, several recently proposed FiWi architectures based on different optical network topologies and WiFi technology are described. Finally, technological challenges toward the realization and commercial adoption of future FiWi access networks are identified.

Smart Microgrids: Optimal Joint Scheduling for Electric Vehicles and Home Appliances

Abstract: The integration of renewable energy sources and electrical vehicles (EVs) into microgrids is becoming a popular green approach. To reduce greenhouse gas emissions, several incentives are given to use renewable energy sources and EVs. By using EVs as electricity storage and renewable energy sources as distributed generators (DGs), microgrids become more reliable, stable, and cost-effective. In this paper, we propose an optimal centralized scheduling method to jointly control the electricity consumption of home appliances and plug-in EVs as well as to discharge the latter ones when they have excess energy, thereby increasing the reliability and stability of microgrids and giving lower electricity prices to customers. We mathematically formulate the scheduling method as a mixed integer linear programming (MILP) problem and solve it to optimality. We compare the optimal solution to that obtained from a scheduling framework, where EVs do not have discharge capabilities, decentralized charge control using game theory and to a solution obtained from a naive scheduling framework.