[1] Mahidol Univ, Dept Math, Fac Sci, Rama 6 Rd, Bangkok 10400, Thailand
[2] CHE, Ctr Excellence Math, 328 Si Ayutthaya Rd, Bangkok 10400, Thailand
[3] Rutgers State Univ, Dept Ind & Syst Engn, 96 Frelinghuysen Rd, Piscataway, NJ 08854 USA
[4] Tsinghua Univ, Dept Ind Engn, Beijing, Peoples R China
[5] Univ Cambridge, Inst Mfg, Dept Engn, 17 Charles Babbage Rd, Cambridge CB3 0FS, England