“…By following the model reduction process presented in Section 3 for each control input, we obtain two reduced-order models as shown in (37), and their mathematical descriptions would depend on where the control inputs are applied. For comparisons, we consider only four pairs of mass locations: (8,9), (7,10), (3,15), and (5,13). Table II shows the comparisons of the total system energy for the four pairs of input locations while subjected to similar levels of control input energy.…”