The mathematical description of entrainment of van der Pol oscillations, though not simple, is at present reasonably well understood. In contrast to this, the physical mechanisms responsible for the phenomenon have remained completely elusive. This paper will show that there are in fact three physically different processes which can cause synchronism, or entrainment. They will be designated as pha...

Results of analog computer experiments are presented which indicate that the phenomenon known traditionally as asynchronous quenching is actually synchronization at large values of the detuning parameter, as had been proposed earlier by Pengilley and Milner. The relationship of these results to earlier analyses of van der Pol and Kobzarev is discussed and certain shortcomings of the Minorsky strob...