1、sec即secant，读音是：英 [si?k?nt]，美 [si?k?nt]。adj. 割的；切的；交差的，n. 割线；正切。

　　2、A new damping estimation method, the secant line method, was presented, that is based on the distance of neighbor peaks and valley of oscillation.摘要提出利用相邻波峰和波谷之间距离估计阻尼比的割线方法。