Influence of infall timescale τ and outflow efficiency b_out on the model results. Different line types correspond to various parameter groups: solid lines (τ,b_out) = (0.1 Gyr,0), dotted lines (τ,b_out) = (15 Gyr,0), and dashed lines (τ,b_out) = (15 Gyr,1). On the left side, the radial profiles of Hi and SFR surface density are shown in the top and bottom panels; on the right side, the radial profiles of H2 and oxygen abundance are shown in the top and bottom panels, respectively. Hi data from Westmeier et al. (2011) are shown with filled squares. SFR data taken from Williams et al. (2013) are denoted with filled triangles and those taken from Gogarten et al. (2010) are shown with filled diamonds. SFR data from Gogarten et al. (2010) are recent SFRs as a function of radius. The observed oxygen abundance from Pilyugin et al. (2014) are shown as open circles, while those from Bresolin et al. (2009) are plotted with filled circles.