  A two-fluid model is proposed to describe the transport properties of
granular superconductors. Using the resistively shunted junction model and some
aspects of the two-level system theory, a statistical model is developed which
takes into account the ratio between the number of normal and superconducting
electrons carrying the applied current. The theoretical model reveals excellent
agreement when compared to transport properties of four high-Tc
superconductors. The results suggest that the two-fluid model is independent of
the sample composition, critical temperature and whether the superconducting
compound is electron or hole-doped.
