1994 Unimodal toroidal chaos

\[\left\{ \begin{array}{l} \dot{x} = z (\lambda x - \mu y ) + (2-z) \left[ \alpha x \left( \displaystyle 1-\frac{x^2+y^2}{R^2} \right) -\beta y \right] \\[0.4cm] \dot{y} = z ( \mu x +\lambda y)+ (2-z) \left[ \alpha y \left( \displaystyle 1- \frac{x^2+y^2}{R^2} \right)+\beta x \right] \\[0.4cm] \dot{z}= \frac{1}{\epsilon} \left[z ( (2-z) \left( \displaystyle a (z-2)^2+b \right) - dx) \left(z+m \left( \displaystyle x^2+y^2 \right)-\eta \right)-\epsilon c(z-1) \right] \end{array} \right. \, .\]