用黎卡堤变换研究如下二阶非线性脉冲微分方程（ 方程式略）得到了两个判断方程振动的充分条件。

Oscillation of a kind of second order nonlinear differential impulsive equation(The equation is abbreviated), is studied and some sufficient conditions are obtained.

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利用空间坐标变换法，得出弯管状屏蔽体的曲面方程式，用精确解析解取代了常用的数值近似解。

The camber equation has been established by means of space alternate coordinate; the numerical approximate calculation is replaced by accurate calculation.

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