Critical transitions and their early warning signals in thermoacoustic systems Induja Pavithran, Vishnu R. Unni and R. I. Sujith Eur. Phys. J. Spec. Top., 230 16-17 (2021) 3411-3432 Published online: 23 July 2021 DOI: 10.1140/epjs/s11734-021-00214-w