Ahmad Moradi

AmirKabir University Of Technology, Mathematics & Computer Science, Graduate Student

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Papers by Ahmad Moradi

On the difficulty of virtual private network instances

by Andrea Lodi and Ahmad Moradi

Networks, 2014

ABSTRACT The virtual private network design problem has attracted an impressive number of theoret... more ABSTRACT The virtual private network design problem has attracted an impressive number of theoretical contributions but, surprisingly, very little computational attempts. This might be due to the fact that the compact formulation proposed in [Altın et al. Networks 49 (2007), 100–115] turned out to be very tight, that is, showing very little or no integrality gap in the computational experiments. In this short note, we first confirm the observations in [Altın et al. Networks 49 (2007), 100–115] by analyzing in detail the behavior of the compact formulation on a larger but similar testbed, and then we provide a set of difficult instances exposing large integrality gaps. This new insight is likely to reinvigorate efforts to develop effective exact computational approaches. © 2014 Wiley Periodicals, Inc. NETWORKS, 2014

On the difficulty of virtual private network instances

by Ahmad Moradi and Andrea Lodi

An effective hybrid PSO-based algorithm for planning UMTS terrestrial access networks

Engineering Optimization, 2010

In this article, an effective hybrid algorithm based on Particle Swarm Optimization (PSO) is prop... more In this article, an effective hybrid algorithm based on Particle Swarm Optimization (PSO) is proposed for planning UMTS (Universal Mobile Telecommunication System) access networks. First, a new encoding scheme based on heuristics is developed, which converts the continuous position values of particles in PSO to multi-constrained and capacitated subnetwork trees with previously dedicated root nodes. Secondly, a local search strategy