  We study numerically the cascading failure problem by using artificially
created scale-free networks and the real network structure of the power grid.
The capacity for a vertex is assigned as a monotonically increasing function of
the load (or the betweenness centrality). Through the use of a simple
functional form with two free parameters, revealed is that it is indeed
possible to make networks more robust while spending less cost. We suggest that
our method to prevent cascade by protecting less vertices is particularly
important for the design of more robust real-world networks to cascading
failures.
