A van der Pol damped SD oscillator, which was proposed by Ruilan Tian, Qingjie Cao and Shaopu Yang (2010, Nonlinear Dynamics, 59, 19-27), is studied. By improving the criterion function of determining the lowest upper bound of the number of zeros of Abelian Integrals, we show that the number of zeros of Abelian integrals of this SD oscillator is two which is sharp.

中文翻译：

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SD振荡器的Poincaré分叉

田瑞兰，曹庆杰，杨少普（2010，非线性动力学，59，19-27）提出了Van der Pol阻尼SD振荡器。通过改进确定Abelian积分零个数的最低上限的判据函数，我们表明该SD振荡器的Abelian积分零个数非常明显。