Finally, the longitudinal expansion thought of high-order cascade filter design was presented.

最后，本文提出了高阶级联滤波器的纵向扩展设计思路。

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By means of the Taylor expansion technique, the asymptotic expressions of the dispersion curves at the long wavelength region were derived for flexural and longitudinal vibration modes.

利用泰勒展开技术，给出了长波区域弯曲振动模式和伸缩振动模式的弥散曲线渐近表达式；

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