Institute of Transportation, MOTC

In practice, the unit cost for transporting freight usually decreases as the amount of freight increases. Hence, in actual operations the transportation cost function can usually be formulated as a concave cost function, causing the transshipment problem an NP-hard problem. The harmony search (HS), a global search algorithm, has led to good results in many applications. Since there has not yet been any research applying HS to minimum concave cost network flow problems, we employ HS, coupled with the techniques of PSO, ACS and TA, to develop a global search algorithms for efficiently solving minimum concave cost network flow problems. Finally, to evaluate our algorithms we designed a network generator to create a sufficient number of problem instances. To evaluate our algorithm, we also tested the recently designed TA, GDA, GA, ACS and PSO that solve minimum concave cost network flow problems. The results show that the developed algorithms performed well in the tests.