  Combinations of Gramian-based centrality measures are used for driver node
selection in complex networks in order to simultaneously take into account
conflicting control energy requirements, like minimizing the average energy
needed to steer the state in any direction and the energy needed for the worst
direction. The selection strategies that we propose are based on a
characterization of the network non-normality, a concept we show is related to
the idea of balanced realization.
