Impulse response of a generalized fractional second order filter
  The impulse response of a generalized fractional second order filter of the form ${{({{s}^{2\alpha}}+a{{s}^{\alpha}}+b)}^{-\gamma}}$ is derived, where $0<\alpha \le 1$, $0<\gamma <2$. The asymptotic properties of the impulse responses are obtained for two cases, and the two cases show the similar properties for the changing of $\gamma$ values. It is shown that only when ${{({{s}^{2\alpha}}+a{{s}^{\alpha}}+b)}^{-1}}$ has the critical stability, the generalized fractional second order filter ${{({{s}^{2\alpha}}+a{{s}^{\alpha}}+b)}^{-\gamma}}$ has different properties as we change the value of $\gamma$. Finally, numerical examples to illustrate the impulse response are provided to verify the proposed concepts. 
Zhuang Jiao and YangQuan Chen
cs.SY math.OC