Renato Natal Jorge is Associate Professor at the Department of Mechanical Engineering at the University of Porto, Portugal.José Carlos Reis Campos is Associate Professor at the Department of Mining Engineering at the University of Porto, Portugal.Mário Augusto Pires Vaz is Associate Professor at the Department of Mechanical Engineering at the University of Porto, Portugal.Sonia Santos works at Med Support - Engenharia & Apoio à Decisão, Ltd., Maia, Porto, Portugal.João Manuel Tavares is Associate Professor at the Department of Mechanical Engineering at the University of Porto, Portugal.