A coupled longitudinal-transverse nonlinear NSGT model for CNTs incorporating internal energy loss Mergen H. Ghayesh, Hamed Farokhi and Ali Farajpour Eur. Phys. J. Plus, 134 4 (2019) 179 Published online: 30 April 2019 DOI: 10.1140/epjp/i2019-12525-2