This kind of periodic orbit is only a phase in a comet's life.

这种周期性轨道只是彗星生命中的一个阶段。

But the periodic orbit of the system must be found, before OGY method can work.

利用OGY方法必须预先知道系统要被稳定的周期轨道，并且这种方法控制的实时性较差。

The close return pairs technique is utilized to estimate an approximate desired periodic orbit.

利用闭回路对技术估计欲稳定周期轨的近似位置。

Then it is proved that the difference periodic orbit preserves the convexity of periodic orbit.

然后证明了差分周期解的凸性不变性。

The stabilization of an unstable periodic orbit in a neighborhood of an unstable fixed point is studied.

讨论了不稳定不动点邻域的不稳定轨道的稳定问题。