  Transport of a Brownian particle moving in a periodic potential is
investigated in the presence of symmetric unbiased external force. The viscous
medium is alternately in contact with the two heat reservoirs. We present the
analytical expression of the net current at quasi-steady state limit. It is
found that the competition of the asymmetric parameter of potential with the
temperature difference leads to the phenomena like current reversal. The
competition between the two driving factors is a necessary but not a sufficient
condition for current reversals.
