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Publications

Publications by LIAAD

2013

A multi-population hybrid biased random key genetic algorithm for hop-constrained trees in nonlinear cost flow networks

Authors
Fontes, DBMM; Goncalves, JF;

Publication
OPTIMIZATION LETTERS

Abstract
Genetic algorithms and other evolutionary algorithms have been successfully applied to solve constrained minimum spanning tree problems in a variety of communication network design problems. In this paper, we enlarge the application of these types of algorithms by presenting a multi-population hybrid genetic algorithm to another communication design problem. This new problem is modeled through a hop-constrained minimum spanning tree also exhibiting the characteristic of flows. All nodes, except for the root node, have a nonnegative flow requirement. In addition to the fixed charge costs, nonlinear flow dependent costs are also considered. This problem is an extension of the well know NP-hard hop-constrained Minimum Spanning Tree problem and we have termed it hop-constrained minimum cost flow spanning tree problem. The efficiency and effectiveness of the proposed method can be seen from the computational results reported.

2013

ANOSOV DIFFEOMORPHISMS

Authors
Almeida, JP; Fisher, AM; Pinto, AA; Rand, DA;

Publication
DISCRETE AND CONTINUOUS DYNAMICAL SYSTEMS

Abstract
We use Adler, Tresser and Worfolk decomposition of Anosov automorphisms to give an explicit construction of the stable and unstable C1+ self-renormalizable sequences.

2013

R&D DYNAMICS

Authors
Becker, J; Ferreira, M; Oliveira, BMPM; Pinto, AA;

Publication
DISCRETE AND CONTINUOUS DYNAMICAL SYSTEMS

Abstract
We study a Cournot duopoly model using Ferreira-Oliveira-Pinto's R&D investment function. We find the multiple perfect Nash equilibria and we analyse the economical relevant quantities like output levels, prices, consumer surplus, profits and welfare.

2013

A projected gradient dynamical system modelling the dynamics of bargaining

Authors
Pinheiro, D; Pinto, AA; Xanthopoulos, SZ; Yannacopoulos, AN;

Publication
JOURNAL OF DIFFERENCE EQUATIONS AND APPLICATIONS

Abstract
We propose a projected gradient dynamical system as a model for a bargaining scheme for an asset for which the two interested agents have personal valuations that do not initially coincide. The personal valuations are formed using subjective beliefs concerning the future states of the world, and the reservation prices are calculated using expected utility theory. The agents are not rigid concerning their subjective probabilities and are willing to update them under the pressure to reach finally an agreement concerning the asset. The proposed projected dynamical system, on the space of probability measures, provides a model for the evolution of the agents, beliefs during the bargaining period and is constructed so that an agreement is reached under the minimum possible deviation of both agents from their initial beliefs. The convergence results are shown using techniques from convex dynamics and Lyapunov function theory.

2013

HEALTH-RELATED QUALITY OF LIFE AND FOOD VARIETY OF EUROPEAN ELDERLY

Authors
Morais, C; Afonso, C; Oliveira, B; Lumbers, M; Raats, M; Almeida, MDV;

Publication
ANNALS OF NUTRITION AND METABOLISM

Abstract

2013

Waist-to-height ratio references for 10 to 18 year-olds in autonomous region of madeira, Portugal

Authors
Sousa, B; Mendes De Oliveira, BM; De Almeida, MDV;

Publication
EUROPEAN JOURNAL OF HEART FAILURE

Abstract

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