there has been extensive work on the existence of periodic solutions for nonlinear second order autonomous differantial equations, but little work regarding the third order problems. the popular poincare-bendixon theorem applies well to the former but not the latter (see [2] and [3]). we give a necessary condition for the existence of periodic solutions for the third order autonomous systems, t...

generally ordering policies are done by two methods, including fix order quantity (foq) and fix order period (fop). these methods are static and either the quantity of ordering or the procedure of ordering is fixing in throughout time horizon. in real environments, demand is varying in any period and may be considered as uncertainty. when demand is variable in any period, the traditional and st...

Inventory control can be done by reducing the cost of inventory and number ordering frequencies economically. PT Tanjung Globalindo Utama or Toko TODA is an oil accessory retail store that provides various needs. Some problems are late delivery goods from suppliers, so for several days company cannot operate optimally. On other hand, has also experienced excess merchandise, wastes due to mercha...