def emf(fbexp, ep_exp):
    """
    Calculate the void fraction at minimum fluidization for the specified bed.

    Parameters
    ----------
    fbexp : float
        Bed expansion factor [-]
    ep_exp : float
        Void fraction in the expanded bed [-]

    Returns
    -------
    e_mf : float
        Void fraction at minimum fluidization [-]
    """

    e_mf = 1 - fbexp * (1 - ep_exp)
    return e_mf