Fig. 2. Particle-size distributions: (a) with constant _y and varying µ_y (thicker lines for µ_y = 2, thinner line for µ_y = 4); (b) with constant µ_y and varying _y (thicker lines for _y = 0.5, thinner line for µ_y = 0.8). The cumulative mass fraction (cmf) is plotted as dash–dot line. cdf, cumulative distribution function; pdf, probability density function.