Lunedi' 27 Aprile 9.30 - 11.00 aula N11, piano terra Mario A. Nascimento (University of Alberta) Titolo: "Optimizing Query Processing in Cache-Aware Wireless Sensor Networks" Abstract This talk will be divided in three parts. In the first part I will give a short introduction to wireless sensor networks (WSNs), their applications and its data management aspect. Next, I will briefly present different problems (and solutions) related to data management within wireless sensor networks that I have work on in the past. Finally, in the third (and longer) part of the talk I will present in more details the work referred to in the title, which is described as follows. Most models for WSNs assume the existence of a base station where query results could in principle be cached, however, the opportunity for re-using such cached data for minimizing data traffic in the WSN has not been well explored thus far. Aiming at filling this gap, we propose an approach that first clips the original query into a polygon after selectively choosing a good subset of the cached queries for reuse. Next, this polygon is partitioned into sub-queries that are then submitted to the WSN. These two problems are interconnected and lead to a combinatorial problem that justifies the use of efficient and effective heuristics. This paper presents algorithms for each of these problems, which are then used within a cost-driven optimization search in order to find a set of sub-queries that minimizes the energy cost of in-network query processing. Experimental results show that our heuristic solution is orders of magnitude faster than an exhaustive search, and yields no more than 10% loss compared to the optimal query processing. Bio Mario A. Nascimento is a Full Professor at (and since July/2014 serves as Chair of) the University of Alberta's Department of Computing Science. He earned his PhD in 1996, and before joining the University of Alberta in 1999, he was a researcher with the Brazilian Agency for Agricultural Research and also an adjunct faculty member with the Institute of Computing of the University of Campinas. In addition, Mario has been a visiting professor at the National University of Singapore's School of Computing (Fall/2005), Aalborg University's Department of Computer Science (Winter/2006), LMU Munich (Fall/2013-Winter/2014) and also had an appointment as Visiting Professor at the Federal University of Ceara in Brazil (2013 and 2014). According to Google Scholar (as of April/2014) his publications have been cited 2,600+ times, earning him an H-index of 26. His main research interests lie in the areas of Spatio-Temporal Data Management and Data Management for Wireless Sensor Networks. Besides often serving as a program committee member for the main database conferences, and as (co) chair of several workshops and symposia, Mario has also served as ACM SIGMOD's Information Director (2002-2005) and ACM SIGMOD Record's Editor-In-Chief (2005-2007). He is currently a member of the VLDB Journal's Editorial Board, the SSTD Endowment's Board of Directors, and has been a senior member of the ACM since 2007. Finally, he finds it amusing to write about himself in the 3rd person.