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2018-10-26

2018-10-26

作者: carpediemmlf | 来源:发表于2018-12-10 06:09 被阅读0次
    • resonance frequency for acceleration response (R(\omega){\omega}^2)

    \omega_{acc} = \omega_0 ( {1 - \frac{1}{2Q^2}} ) ^ {-\frac{1}{2}}

    • for completeness, listing the resonance frequency for the three quantities in question

    \omega_{A} = \omega_0 ( {1 - \frac{1}{2Q^2}} ) ^ {\frac{1}{2}}

    \omega_{velo} = \omega_0

    \omega_{acc} = \omega_0 ( {1 - \frac{1}{2Q^2}} ) ^ {-\frac{1}{2}}

    • notice \omega_a \cdot \omega_{acc} = {\omega_0}^2 by comparing with the resonance frequency for displacement as discussed last time

    Mean power: \frac{1}{2} |F_0||v_0|\cos ({\phi_F}-{\phi_v})

    • \mathcal{Re}\{\bf A\} \mathcal{Re}\{\bf B\} = \frac{1}{2} \mathcal{Re}\{ {\bf A} {\bf B^{\dagger}} \} is true when \bf A and \bf B have the same time dependence (e.g., both propagating forward/backward in time) in their complex power representation
    • \langle P_{dissipated} \rangle = \frac{1}{2} b{|v_0|}^2, where b=\gamma m

    Power resonance and bandwidth

    • Consider the half power points, whose difference gives the bandwidth
      \Delta \omega = \omega_{+} - \omega_{-} = \gamma

    Q = \frac{\omega_0}{\gamma} = \frac{\omega_0}{\Delta \omega}

    • this provides a second definition of the quality factor

    Canonical form of the LCR circuit equation

    \omega_0 = \frac{1}{\sqrt{LC}}

    \gamma = \frac{R}{L}

    Q = \frac{\omega_0}{\gamma} = \frac{1}{R}\sqrt \frac{L}{C}

    \ddot q + \gamma \dot q + {\omega_0}^2 q = \frac {V} {L}

    Impedance: Force divided by the velocity

    Z = \frac{F}{v}

    • encapsulating both magnitude and phase shift information

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