How can I give time varying temperature dependent heat source term in COMSOL Multiphysics?

Question

The conditions are as follows: 0<t<0.1 sec, Q= Q_1 W/m^3 0.1<t<2.1 sec, Q= 0 W/m^3 2.1<t<2.2 sec, Q= Q_2 W/m^3 2.2<t<4.2 sec, Q= 0 W/m^3 Where, both Q_1 and Q_2 are a function of temperature, which I have already defined in Global Definitions.