Material A to Material B, the following equation
    is used to determine the temperature of the interior nodes:

    $$T_m^{p+1} = Fo_A * T_{m-1}^p +Fo_{AB}*T_{m+1}^p + (1-Fo_A - Fo_{AB})*T_m^p$$

    Similarly, in the transition from Material B to Material A, the following
    equation is used:

    $$T_m^{p+1} = Fo_B * T_{m+1}^p +Fo_{BA}*T_{m-1}^p + (1-Fo_B - Fo_{BA})*T_m^p$$

	Temperatures for nodes internal to Material A are determined by:
    $$ T_m^{p+1} = Fo_B *(T_{m+1}^p + T_{m-1}^p) + (1-2*Fo_B)*T