Before revision: In this paper, we extend the 3/2-model for VIX studied by Goard and Mazur (2013) and introduce  generalized 3/2 and 1/2 classes for volatility .
After revision: In this paper, we extend the 3/2-model for VIX studied by Goard and Mazur (2013) and introduce generalized 3/2 and 1/2 classes of volatility processes .