Propagating solitons in damped ac-driven chains.

It is demonstrated that an external ac field may support stable propagation of solitons and cnoidal waves in a chain of interacting particles in the presence of friction, provided that the drive amplitude exceeds a certain threshold value. The effect is analyzed in the general form, and is then considered in detail both for the Toda lattice with weak friction and for a string of hard beads with arbitrary friction. The effects disappears in the continuum limit.