For these two cases the improved describing function is used in analysis to obtain the sufficient conditions for asymptotic stability and for sustained oscillation .

对以上两种情况分别用 计及 高次谐波的描述函数法进行分析，从而得到了 系统渐近稳定和 产生 自 振的充分条件。

In the experiment it is found that at a certain external flow velocity and cavity size a strongly self sustained flow oscillation in the cavity would appear .

实验发现，在一定的气流速度和空腔几何尺寸下，空腔内流动会出现强烈的 自持 振荡。

The result of simulation and the debug of actual digital servo system shows that the controller can effectively get rid of the sustained oscillation of the system caused by the backlash characteristics and can improve the system accuracy .

实际数字交流伺服系统调试结果表明该控制算法能有效减小 间隙特性对系统的影响。