def w_in(vel_in=accel_to_vel(), Y=Y_flr_section, Yi=Y_Zmounts()[1], Ys=Y_Zengine()[1], Yb=Y_Zbeam()[1], dB=False):
    """input power from the engine to the vehicle, velocity calculated from the
   accleration spectrum, and going through vib isolation"""
    top = [np.real(Y+Yb1)*((vel_in1)**2) for vel_in1,Yb1 in zip(vel_in, Yb)]
    bottom = [pow(np.abs(Y+Yb1+Yi1+Ys1+Yb1), 2) for Yb1,Yi1,Ys1,Yb1 in zip(Yb,Yi,Ys,Yb)]
    w = [t/b for t,b in zip(top,bottom)]
    if dB == False:
        return w
    if dB == True:
        Lp = [10*np.log10(w1/PWL_ref) for w1 in w]
        return Lp