Unfortunately, the original version of this article [1] contained an error. The authors noted an error only in the HTML version of their article. The equation (8) has a typo in it. It is shown as:

$$ \mathrm{D}\left(\mathrm{V},\backslash,\ \mathrm{W}\ \mathrm{H}\right) $$

However it should be shown as the following:

$$ \mathrm{D}\left(\mathrm{V},\ \mathrm{W}\ \mathrm{H}\right) $$