What does this equation mean? Include the variables meaning. $\frac{kLa{d}^2}{D_L}=0\mathrm{.}060(\frac{d^2{N}_p}{}{)}^{1\mathrm{.}5}(\frac{d{N}^2}{g}{)}^{0\mathrm{.}19}*(\frac{}{D_L}{)}^{0\mathrm{.}5}(\frac{V_s}{}{)}^{0\mathrm{.}6}(\frac{Nd}{V_s}{)}^{0\mathrm{.}32}$