Pablo Adasme

Bio: Pablo Adasme is an academic researcher from University of Santiago, Chile. The author has contributed to research in topics: Variable neighborhood search & Visible light communication. The author has an hindex of 8, co-authored 73 publications receiving 198 citations. Previous affiliations of Pablo Adasme include University of Paris-Sud.

Potential and challenges of VLC based IPS in underground mines

Abstract: Chile is the largest copper producer in the world In the world, almost 40% of copper is produced underground and it is expected that the activity will reach the 60% of the total mining activity Because of this, there will be new challenges in terms of safety and productivity Visible Light Communications (VLC) is a new technology capable to provide illumination and communication at the same time This technology has shown high accuracy in localization and tacking for indoor scenarios Nevertheless, most of the applications that can be found in literature assumes square rooms, no tilt receivers, and Line of Sight (LOS) link In this paper we will address the problem of enabling Visible Light Communications (VLC) based Indoor Positioning System (IPS) in underground mines Feasible link configurations and positioning topologies are studied throughout this paper In addition to this, different localization methods are classified in two groups, ie, range based and range free methods Their performance in terms of accuracy and robustness as well as the constraints of each method will be analyzed for its usage in underground mines

Stochastic maximum weight forest problem

Abstract: In this article, we investigate the stochastic maximum weight forest problem. We present two mathematical formulations for the problem: a polynomial sized one based on the characterization of forests in graphs and a formulation with an exponential number of constraints. We give a proof of the correctness of the new formulation and present a polynomial reduction from the set cover problem to give some insight about the complexity of this problem. We introduce an L-shaped decomposition approach for the polynomial formulation, thus allowing the optimal solution of large scale instances with up to 90 nodes. Finally, we propose a Kruskal based variable neighborhood search VNS metaheuristic to compute near optimal solutions with significantly less computational effort. Our numerical results show that the VNS approach provides tight near optimal solutions with a gap less than 1% for most of the instances. © 2015 Wiley Periodicals, Inc. NETWORKS, Vol. 654, 289-305 2015

Improved solution strategies for dominating trees

Abstract: Intelligent systems in Wireless Sensor Networks (WSN) allow to eliminate duplicated sensed data and to efficiently route them to a central processing unit. Thus, augmenting WSN lifetime while keeping sensors connectivity and routing the sensed information through an optimized network structure. This work discusses a set of improved exact solution strategies that were effective to the design of a minimum energy consumption structure for the sensors data communication. We present an extended version of a primal-dual model for the minimum cost dominating tree (DT) problem, as well as valid inequalities to improve its linear relaxation. We discuss structural properties of dominating sets and trees used to conceive efficient cutting plane strategies. We adapt accordingly reduction techniques from dominating sets to the DT problem. The new solution techniques allow to handle to optimality challenging benchmark and new randomly generated DT instances with up to 100 nodes, which was not possible to achieve with state-of-the-art models for the problem.

I and i

Abstract: There is, I think, something ethereal about i —the square root of minus one. I remember first hearing about it at school. It seemed an odd beast at that time—an intruder hovering on the edge of reality. Usually familiarity dulls this sense of the bizarre, but in the case of i it was the reverse: over the years the sense of its surreal nature intensified. It seemed that it was impossible to write mathematics that described the real world in …

A User’s Guide

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Algorithm engineering in robust optimization

Abstract: Robust optimization is a young and emerging field of research having received a considerable increase of interest over the last decade. In this paper, we argue that the algorithm engineering methodology fits very well to the field of robust optimization and yields a rewarding new perspective on both the current state of research and open research directions.

OFDM for Optical Communications

Abstract: Orthogonal frequency division multiplexing (OFDM) is a modulation technique which is now used in most new and emerging broadband wired and wireless communication systems because it is an effective solution to intersymbol interference caused by a dispersive channel. Very recently a number of researchers have shown that OFDM is also a promising technology for optical communications. This paper gives a tutorial overview of OFDM highlighting the aspects that are likely to be important in optical applications. To achieve good performance in optical systems OFDM must be adapted in various ways. The constraints imposed by single mode optical fiber, multimode optical fiber and optical wireless are discussed and the new forms of optical OFDM which have been developed are outlined. The main drawbacks of OFDM are its high peak to average power ratio and its sensitivity to phase noise and frequency offset. The impairments that these cause are described and their implications for optical systems discussed.