運(yùn)籌學(xué)與供應(yīng)鏈管理-第4講-文庫吧資料
2024-10-25 02:48本頁面
【正文】 y approximate the demand history using a continuous distribution. By far, the most popular distribution for inventory applications is the normal. A normal distribution is determined by two parameters: the mean and the variance ?2? 全國領(lǐng)先的工作效率提升平臺(tái) Inventory Control with Uncertain Demand These can be estimated from a history of demand by the sample mean and the sample variance . D 2s???niiDnD11? ??????nii DDns12211 全國領(lǐng)先的工作效率提升平臺(tái) Inventory Control with Uncertain Demand The normal density function is given by the formula We substitute as the estimator for and as the estimator for . ? ? ???????????????????? ??? xxxf f or 21e xp21 2????D ? s? 全國領(lǐng)先的工作效率提升平臺(tái) Inventory Control with Uncertain Demand 00 2 4 6 8 10 12 14 16 18 20 2224 24 26 全國領(lǐng)先的工作效率提升平臺(tái) Optimization Criterion In general, optimization in production problems means finding a control rule that achieves minimum cost. However, when demand is random, the cost incurred is itself random, and it is no longer obvious what the optimization criterion should be. Virtually all of the stochastic optimization techniques applied to inventory control assume that the goal is to minimize expected costs. 全國領(lǐng)先的工作效率提升平臺(tái) The Newsboy Model (Continuous Demands) The demand is approximately normally distributed with mean and standard deviation . Each copy is purchased for 25 cents and sold for 75 cents, and he is paid 10 cents for each unsold copy by his supplier. One obvious solution is approximately 12 copies. Suppose Mac purchases a copy that he doesn39。Wv? ?WRR vvv ??39。39。39。39。39。39。39。 RWWR vnvnAAnF ??????? ?? 全國領(lǐng)先的工作效率提升平臺(tái) Two Stage Echelon Inventory A convenient way is to first set which gives This solves for ? ? 0??? nFn? ? 039。* ??????? ??? ? ? ?39。*????????? 全國領(lǐng)先的工作效率提升平臺(tái) Two Stage Echelon Inventory Substitute the result into the cost equation We recognize that the n that minimizes the simpler expression ? ? ? ? rvnvDnAAn RWWR 2T R C 39。2 ????????? ???? ? RWWRRRvnvrnAAQDQ? ? ? ?rvnvDnAAnQRWWRR 239。2,T R C RWRWRRR vnvrQnAAQDQn ???????? ??? ? 02T R C 39。222T R CRWRWRRRRRRWRRWRWvnvrQnAAQDrvDArvQnnQDA,?????????????? 全國領(lǐng)先的工作效率提升平臺(tái) Two Stage Echelon Inventory Select (an integer) and in order to minimize Partial derivation of TRC n RQ? ? ? ?39。39。RI 全國領(lǐng)先的工作效率提升平臺(tái) Two Stage Echelon Inventory Twostage process: Substituting from equation () and noting that the echelon stocks follow sawtooth patterns, ? ?? ?39。T R C ????39。39。 全國領(lǐng)先的工作效率提升平臺(tái) Two Stage Echelon Inventory Twostage process: The total relevant (setup plus carrying) costs per unit time are given by = average value of the warehouse echelon inventory, in units = average value of the retailer echelon inventory, in units ? ? rvIQ DArvIQ DA, RRRRWWWWRW 39。 全國領(lǐng)先的工作效率提升平臺(tái) 第４講 庫存管理（ II） 全國領(lǐng)先的工作效率提升平臺(tái) MultiEchelon Inventory in Supply Chain Outsi de suppl ier (s)C e ntra l wa re houseB ra nc h wa re houseR e tail out letsC ust omer sB ra nc h wa re house 全國領(lǐng)先的工作效率提升平臺(tái) Two Stage Echelon Inventory Sequential stocking points with level demand Twostage process Q WWarehouse inventory levelTim eTim eQ RRetailerinventory levelAc tual phy si c a l i nve ntory l
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