【正文】 )(39。預測值乘以一個代表盤點周期、補貨提前期，以及包含需求預測和提前期不確定性的時間增量的因子，就得到目標值。 =??=?= AA szXMAX72 Joint Ordering Example (Cont’d) which has an average inventory of units )()2/30( Avg.)()2/(Inventory Avg.A39。 )i i i dM T L T z s= + +總相關(guān)成本 =訂購成本 +經(jīng)營性庫存持有成本 +安全庫存持有成本 +缺貨成本 ( z )1( 39。 ?=MAX s′ Z(s′) 65 Periodic Review (Cont’d) where *470)(50)(39。**61 CR (2023) Prentice Hall, Inc. Periodic review control with demand uncertainty 按預先確定的周期（ T)核查某種產(chǎn)品的庫存。由此 s39。S2DQ (z) dRevise P ()11,107(12) 0)()12,872( =?=Now, = and E()= 55 CR (2023) Prentice Hall, Inc. Reorder Point Control (Cont’d) Revise Q units 13,() )()](3,79512)[102(11,107)( =?=QContinue to revise Q and P until no further change occurs. P=78% and Q=13,395 units. Note Although the instock probability during the lead time is 78%, the actual service level is SL=96% 56 Reorder point control with demand and lead time uncertainties )()( 22239。= = 49 CR (2023) Prentice Hall, Inc. With known stockout costs k 如果缺貨成本已知，就沒必要規(guī)定客戶服務水平了，可以將服務和成本的最佳平衡點計算出來。d) ? 在前例中， ? 平均庫存 =322/2+*=201(個） 47 Reorder Point Control (Cont’d) Total relevant cost The total relevant cost equation is now extended to include the costs of safety stock as well as outofstock. The outofstock cost (k) is $2/unit. The price term is dropped. Hence, $))((322600,22)40)(5)((2322)5)((322)10(600,22 )(39。( dszLT ??= d41 CR (2023) Prentice Hall, Inc. Given: d = 50 units/week C = $5/unit sd = 10 units/week LT = 3 weeks I = 10%/year P = 99% during lead time S = $10/order Find Q* and ROP From the EOQ formula units (5) 0)2(50x52)(1 ==*QGood method for products: 1. Of high value 2. That are purchased from one vendor or plant 3. Having few economies of scale in production, purchasing, or transportation 924 42 CR (2023) Prentice Hall, Inc. Reorder Point Control for a Single Item ROP Quantity on hand 0 Q Q Receive order Place order Stockout LT Time LT DDLT P 925 43 CR (2023) Prentice Hall, Inc. ROP Q 0 Inventory level LT LT Time Safety stock Reorder Point Control for a Single Item Actual on hand Quantity on hand +on order ?backorders Quantity for control 926 44 Weekly demand is normally distributed with a mean of d = 100 and a standard deviation of sd = 10 Lead time is 3 weeks Reorder Point Control (Cont’d) Finding the reorder point requires an understanding of the demandduringleadtime distribution sd=10 d =100 sd=10 d =100 sd=10 d =100 + + = Week 3 Week 2 Week 1 z P DDLT X = 300 ROP 300100( 3)=====?=LTssLTdXd39。 z d = = = = = = = = = = = = = = = = = = = = = 27 ? 產(chǎn)或采購期間的需求量 ? ? ? ? ? ，將超過總凈需求的部分分配到各存儲點 ? 每個存儲點的貨物總量 28 ? （ 1）需求是一次性的、高季度性的或持續(xù)性的情況 ? （ 2）訂貨程序在某一庫存水平上啟動或由庫存盤點程序啟動 ? （ 3）需求和補貨提前期存在不同程度不確定性的情況 29 CR (2023) Prentice Hall, Inc. Single Order Purchasing Make a onetime purchase of an item. How much to order? Procedure: 平衡利潤增加額與損失增加額 利潤 =單位價格 單位成本 損失 = 單位成本 單位殘值 如果考慮一定量產(chǎn)品被售出的概率 CPn，預期收益和預期損失在以下點得到平衡 CPn x 損失 = (1 CPn) x 利潤 or CPn = 利潤 /(利潤 + 損失 ) CPn代表至多售出 n個單位產(chǎn)品的累積概率 Daily stocking of newspapers in vending machines is a good example 918 30 CR (2023) Prentice Hall, Inc. Single Order Purchasing Make a onetime purchase of an item. How much to order? Procedure: Balance incremental profit against incremental loss. Profit = Price per unit ? Cost per unit Loss = Cost per unit ? Salvage value per unit If CPn is probability of n units being sold, then CPn x Loss = (1 ? CPn) x Profit or CPn = Profit/(Profit + Loss) Now, increase order quantity until CPn just matches cumulative probability of selling additional units. Daily stocking of newspapers in vending machines is a good example 918 31 CR (2023) Prentice Hall, Inc. Single Order Purchasing (Cont’d) Example A clothing item is purchased for a seasonal sale. It costs $35, but it has a sale price of $50. After the season is over, it is marked down by 50% to clear the merchandise. The estimated quantities to be sold are: Number of items, n Probability of selling exactly n items Cumulative probability 10 15 20 25 30 35 919 32 CR (2023) Prentice Hall, Inc. Single Order Purchasing (Cont’d) Solution Profit = $5035 = $15 Loss = $35 ()(50) = $10 CPn = 15/(15 + 10) = CPn is between 15 and 20 items, round up and order 20 items. 33 2ICDS TC?=?= 庫存持有成本采購成本 TC—每年總的相關(guān)成本（美元） Q—補充存貨的訂單批量（件） D—對庫存產(chǎn)品的年需求量（件） S—采購成本（美元 /訂單） C—庫存產(chǎn)品的價值（美元 /件） I—庫存持有成本占產(chǎn)品價值的比例（ %/年） Develop a simple control system by finding the replenishment quantity (Q) and the reorder point (ROP). The relevant total cost is:總成本 =采購成本和庫存成本 注 :需求和提前期確定—周期性的庫存管理 921 34 2ICDS TC?=?= 庫存持有成本采購成本 TC—每年總的相關(guān)成本（美元） Q—補充存貨的訂單批量（件） D—對庫存產(chǎn)品的年需求量（件） S—采購成本（美元 /訂單） C—庫存產(chǎn)品的價值（美元 /件） I—庫存持有成本占產(chǎn)品價值的比例（ %/年） Develop a simple control system by finding the replenishment quantity (Q) and the reorder point (ROP). The relevant total cost is:總成本 =采購成本和庫存成本 Note: No uncertainty in demand or lead time—manage regular (cycle) stock only 921 35 CR (2023) Prentice Hall, Inc. 0 Time Lead time Lead time Order Placed Order Placed Order Received Order Received Inventory Level Reorder point, R Q Reorder Point Method Under Certainty for a Single Item Quantity onhand plus onorder 922 36 Given: d = 50 units/week I = 10%/year S = $10/order C