The transport of an underdamped Brownian particle moving in a one-dimension
al ratchet driven by a modulated Gaussian white noise is considered. The sy
stem experiences periodically higher temperature T-1 during a time tau(1) a
nd lower temperature T-2 during a time tau(2). Both the average current and
the thermal efficiency are calculated numerically. The results show that t
he efficiency of energy transformation can be optimized for a ratio of tau(
1)/tau(2) less than 1 at a critical damping. (C) 2000 Published by Elsevier
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