On the weakly dissipative Camassa-Holm, Degasperis-Procesi, and Novikov   equations
  We show that the weakly dissipative Camassa-Holm, Degasperis-Procesi, Hunter-Saxton, and Novikov equations can be reduced to their non-dissipative versions by means of an exponentially time-dependent scaling. Hence, up to a simple change of variables, the non-dissipative and dissipative versions of these equations are equivalent. Similar results hold also for the equations in the so-called b-family of equations as well as for the two-component and \mu-versions of the above equations. 
Jonatan Lenells, Marcus Wunsch
math.AP