478315.fig.005a
(a)
478315.fig.005b
(b)
Figure 5: (a) The cusp of codimension breaks into a stable focus and a hyperbolic saddle when , . The change of stability of the focus yields an unstable limit cycle. (b) The unstable limit cycle is broken when , , reachs the manifold of the saddle , and leads to a homoclinic loop occur.