Electronic Journal of Differential Equations,
Vol. 2019 (2019), No. 107, pp. 1-23.

Title: Limit cycles in piecewise smooth perturbations of a quartic isochronous center

Authors: Haifeng Song (Beihang Univ., Beijing, China)
         Linping Peng (Beihang Univ., Beijing, China)
         Yong Cui     (Beihang Univ., Beijing, China)

Abstract:
 This article concerns the bifurcation of limit cycles from a quartic integrable
 and non-Hamiltonian system. By using the first order averaging method
 and some mathematical technique on estimating the number of the
 zeros, we show that under a class of piecewise smooth quartic
 perturbations, seven is a lower and twelve an upper  bound for
 the maximum number of limit cycles bifurcating from the
 unperturbed quartic isochronous center.

Submitted April 9, 2019. Published September 18, 2019.
Math Subject Classifications: 37G15, 37D45, 34C07.
Key Words: Averaging method; piecewise smooth perturbation; limit cycle;
           quartic isochronous center, ECT-system.