53Production/Distribution/Routing Planning for Supply Chain Networks
similar to those in Equations 3.1 through 3.7 are included and a material
transform factor Γ is used to dene the rate of raw materials consumption:
mt mt mi mit
i
,, ,, ,−
∀
+−
1
Γ , ∀m, t. The solution of the proposed GA algo-
rithm is compared with that obtained by CPLEX. Among randomly gener-
ated test problems, the solution time of GA is quite stable, averaging from 334
to 546 seconds, while that required by the CPLEX solver exhibits exponential
growth with respect to problem size, from 32 to 67,854 seconds to obtain the
optimal solutions. The proposed GA also demonstrates strong performance,
with an average error gap of 0.2%. Gen and Syarif (2005) propose a GA-base ...