Limit cycles in two plane non-Hamiltonian perturbed integrable systems

According to the detection functions and qualitative analysis, we investigated the limit cycle bifurcations in two plane non-Hamiltonian perturbed integrable systems. The research shows that each of the two systems has 3 limit cycles. And by numerical simulations, the distributed orderliness of these limit cycles is observed, their exact places are determined. The investigation also indicates that each of these limit cycles passes the corresponding exact point.