庫存決策CR(2004)PrenticeHall,Inc.Chapter9每一個(gè)管理上的失誤最后都會(huì)變成庫存?！癊verymanagementmistakeendsupininventory.”MichaelC.BergeracFormerChiefExecutiveRevlon,Inc.1產(chǎn)品計(jì)劃三角形ProductinthePlanningTriangleCR(2004)PrenticeHall,Inc.PLANNINGORGANIZINGCONTROLLINGTransportStrategy?Transportfundamentals?TransportdecisionsCustomerservicegoals?Theproduct?Logisticsservice?Oc.&info.sys.InventoryStrategy?Forecasting?Inventorydecisions?Purchasingandsupplyschedulingdecisions?Storagefundamentals?StoragedecisionsLocationStrategy?Locationdecisions?Thenetworkplanningprocess計(jì)劃組織控制TransportStrategy?Transportfundamentals?TransportdecisionsCustomerservicegoals?Theproduct?Logisticsservice?Oc.&info.sys.InventoryStrategy?Forecasting?Inventorydecisions?Purchasingandsupplyschedulingdecisions?Storagefundamentals?StoragedecisionsLocationStrategy?Locationdecisions?Thenetworkplanningprocess庫存戰(zhàn)略預(yù)測(cè)客戶服務(wù)目標(biāo)采購和供應(yīng)時(shí)間決策存儲(chǔ)基礎(chǔ)知識(shí)存儲(chǔ)決策產(chǎn)品物流服務(wù)訂單管理和信息系統(tǒng)庫存決策運(yùn)輸戰(zhàn)略運(yùn)輸基礎(chǔ)知識(shí)運(yùn)輸決策選址戰(zhàn)略選址決策網(wǎng)絡(luò)規(guī)劃流程2InventoryDecisionsinStrategyCR(2004)PrenticeHall,Inc.PLANNINGORGANIZINGCONTROLLINGTransportStrategy?Transportfundamentals?TransportdecisionsCustomerservicegoals?Theproduct?Logisticsservice?Oc.&info.sys.InventoryStrategy?Forecasting?Inventorydecisions?Purchasingandsupplyschedulingdecisions?Storagefundamentals?StoragedecisionsLocationStrategy?Locationdecisions?ThenetworkplanningprocessPLANNINGORGANIZINGCONTROLLINGTransportStrategy?Transportfundamentals?TransportdecisionsCustomerservicegoals?Theproduct?Logisticsservice?Oc.&info.sys.InventoryStrategy?Forecasting?Inventorydecisions?Purchasingandsupplyschedulingdecisions?Storagefundamentals?StoragedecisionsLocationStrategy?Locationdecisions?Thenetworkplanningprocess3CR(2004)PrenticeHall,Inc.什么是庫存WhatareInventories?庫存就是在企業(yè)生產(chǎn)和物流渠道中各點(diǎn)堆積的原材料、供給品、零部件、半成品和成品。4CR(2004)PrenticeHall,Inc.WhereareInventories?MaterialsourcesInboundtransportationProductionOutboundtransportationFinishedgoodswarehousingCustomersInventorylocationsFinishedgoodsShippingInventoriesin-processReceivingProductionmaterials9-4原料來源生產(chǎn)內(nèi)向運(yùn)輸外向運(yùn)輸成品儲(chǔ)存客戶原材料半成品成品庫存選址5CR(2004)PrenticeHall,Inc.9.1對(duì)庫存的評(píng)述9.1.1庫存原因ReasonsforInventories1.改善客戶服務(wù)2.降低成本首先，保有庫存可以使生產(chǎn)的批量更大、批次更少，運(yùn)作水平更高，因而產(chǎn)生經(jīng)濟(jì)效益其次，保有庫存有助于實(shí)現(xiàn)采購和運(yùn)輸中的成本節(jié)約第三，先期購買可以在當(dāng)前交易的低價(jià)位購買額外數(shù)量的產(chǎn)品。第四，抵銷生產(chǎn)和運(yùn)輸過程中的不確定性第五，應(yīng)付突發(fā)事件。6CR(2004)PrenticeHall,Inc.9.1對(duì)庫存的評(píng)述9.1.1庫存原因ReasonsforInventoriesImprovecustomerserviceProvidesimmediacyinproductavailabilityEncourageproduction,purchase,andtransportation economiesAllowsforlongproductionrunsTakesadvantageofprice-quantitydiscountsAllowsfortransporteconomiesfromlargershipmentsizesActasahedgeagainstpricechangesAllowspurchasingtotakeplaceundermostfavorableprice termsProtectagainstuncertaintiesindemandandleadtimesProvidesameasureofsafetytokeepoperations runningwhendemandlevelsandleadtimescannotbeknown forsureActasahedgeagainstcontingenciesBuffersagainstsucheventsasstrikes,fires,and disruptionsinsupply7CR(2004)PrenticeHall,Inc.9.1.2反對(duì)保有庫存的原因ReasonsAgainstInventories第一，庫存被認(rèn)為是一種浪費(fèi)第二，庫存可能掩蓋質(zhì)量問題第三，保有庫存鼓勵(lì)人們以獨(dú)立的觀點(diǎn)來看待物流渠道整體的管理問題8CR(2004)PrenticeHall,Inc.9.1.2反對(duì)保有庫存的原因ReasonsAgainstInventoriesTheyconsumecapitalresourcesthatmightbeputto betteruseelsewhereinthefirmTheytoooftenmaskqualityproblemsthatwouldmore immediatelybesolvedwithouttheirpresenceTheydivertmanagement’sattentionawayfromcareful planningandcontrolofthesupplyanddistribution channelsbypromotinganinsularattitudeabout channelmanagement9流通渠道Pipeline（Inventoriesintransit）投機(jī)SpeculativeGoodspurchasedinanticipationofpriceincreases定期性或周期性特征Regular/Cyclical/SeasonalInventoriesheldtomeetnormaloperatingneeds安全SafetyExtrastocksheldinanticipationofdemandand leadtimeuncertainties倉耗Obsolete/DeadStockInventoriesthatareoflittleornovalueduetobeing outofdate,spoiled,damaged,etc.9.2庫存類型TypesofInventories10持久性需求求PerpetualdemandContinueswellintotheforeseeablefuture季節(jié)性需求求SeasonaldemandVarieswithregularpeaksandvalleysthroughouttheyear尖峰需求LumpydemandHighlyvariable規(guī)律性需求求RegulardemandNothighlyvariable(3<Mean)終端需求TerminatingdemandDemandgoesto0inforeseeablefuture派生需求DeriveddemandDemandisdeterminedfromthedemandofanotheritemofwhichitisapart9.3庫存存管理類型型的分類9.3.1需求特點(diǎn)點(diǎn)NatureofDemandAccuratelyforecastingdemandissinglythemostimportantfactoringoodinventorymanagement11CR(2004)PrenticeHall,Inc.拉動(dòng)式庫存存管理法Pull基于每個(gè)倉倉庫的特定定需求以一一定的訂貨貨批量補(bǔ)足足庫存每一個(gè)存儲(chǔ)儲(chǔ)點(diǎn)獨(dú)立Eachstockinglocationisconsideredindependent最大化控制制庫存Maximizeslocalcontrolofinventories推動(dòng)式庫存存管理法Push根據(jù)總需求求分配產(chǎn)品品到庫存點(diǎn)點(diǎn)鼓勵(lì)規(guī)模生生產(chǎn)準(zhǔn)時(shí)生產(chǎn)制制Just-in-time同步庫存流流量以滿足足需求Attemptstosynchronizestockflowssoastojustmeetdemandasitoccurs最小化庫存存Minimizestheneedforinventory9.3.2管理思想想InventoryManagementPhilosophies12CR(2004)PrenticeHall,Inc.拉動(dòng)式庫存存管理法PullDrawsinventoryintothestockinglocationEachstockinglocationisconsideredindependentMaximizeslocalcontrolofinventories推動(dòng)式庫存存管理法PushAllocatesproductiontostockinglocationsbasedonoveralldemandEncourageseconomiesofscaleinproduction準(zhǔn)時(shí)生產(chǎn)制制Just-in-timeAttemptstosynchronizestockflowssoastojustmeetdemandasitoccursMinimizestheneedforinventory9.3.2管理思想想InventoryManagementPhilosophies13CR(2004)PrenticeHall,Inc.供給驅(qū)動(dòng)Supply-Driven供應(yīng)量和時(shí)時(shí)間未知Supplyquantitiesandtimingareunknown所有的供應(yīng)應(yīng)必須接受受和處理Allsupplymustbeacceptedandprocessed通過需求控控制庫存Inventoriesarecontrolledthroughdemand聯(lián)合控制AggregateControl項(xiàng)目目分分類類項(xiàng)目目組組根根據(jù)據(jù)基基于于80-20法法則則確確定定的的銷銷售售水水平平為3個(gè)個(gè)或或以以上上的的產(chǎn)產(chǎn)品品組組合合允允許許不不同同的的庫庫存存策策略略9.3.2管管理理思思想想InventoryManagementPhilosophies14PlantWarehouse#1Warehouse#2Warehouse#3A1A2A3A=AllocationquantitytoeachwarehouseQ=Requestedreplenishmentquantity

byeachwarehouseQ1Q2Q3DemandforecastDemandforecastDemandforecastPULL-ReplenishinventorywithordersizesbasedonspecificneedsofeachwarehousePUSH

-Allocatesupplytoeachwarehousebasedontheforecastforeachwarehouse拉動(dòng)動(dòng)式式或或推推動(dòng)動(dòng)式式庫庫存存管管理理思思想想Pullvs.PushInventoryPhilosophiesCR(2004)PrenticeHall,Inc.9-11推動(dòng)動(dòng)式式————基基于于每每個(gè)個(gè)倉倉庫庫的的預(yù)預(yù)測(cè)測(cè)將將供供給給分分配配給給各各個(gè)個(gè)倉倉庫庫拉動(dòng)動(dòng)式式————基基于于每每個(gè)個(gè)倉倉庫庫的的特特定定需需求求以以一一定定訂訂貨貨批批量量補(bǔ)補(bǔ)足足庫庫存存A——將將產(chǎn)產(chǎn)品品分分配配到到各各個(gè)個(gè)倉倉庫庫Q——每每個(gè)個(gè)倉倉庫庫需需要要的的補(bǔ)補(bǔ)貨貨量量159.3.3產(chǎn)產(chǎn)品品匯匯總總程程度度多數(shù)數(shù)庫庫存存管管理理是是針針對(duì)對(duì)每每一一種種產(chǎn)產(chǎn)品品的的庫庫存存進(jìn)進(jìn)行行控控制制。?！宰韵孪露仙戏ǚ硪灰环N種方方法法是是管管理理一一類類產(chǎn)產(chǎn)品品而而不不是是管管理理單單獨(dú)獨(dú)一一種種產(chǎn)產(chǎn)品品————自自上上而而下下法法169.3.4多多層層級(jí)級(jí)庫庫存存供應(yīng)應(yīng)鏈鏈管管理理鼓鼓勵(lì)勵(lì)管管理理者者將將供供應(yīng)應(yīng)渠渠道道中中更更多多的的部部分分包包括括到到計(jì)計(jì)劃劃過過程程中中來來，，供供應(yīng)應(yīng)渠渠道道中中多多個(gè)個(gè)層層級(jí)級(jí)的的庫庫存存也也成成為為核核心心問問題題。。179.3.5虛虛擬擬庫庫存存虛擬擬庫庫存存即即將將自自己己將將來來所所可可能能需需要要而而又又沒沒有有的的東東西西的的所所有有相相關(guān)關(guān)信信息息建建立立檔檔案案，，包包括括品品名名規(guī)規(guī)格格價(jià)價(jià)格格數(shù)數(shù)量量等等，，在在需需要要時(shí)時(shí)能能使使用用上上。。189.4庫庫存存目目標(biāo)標(biāo)InventoryManagementObjectivesGoodinventorymanagementisacarefulbalancingactbetweenstockavailabilityandthecostofholdinginventory.CustomerService,

i.e.,StockAvailabilityInventoryHoldingcostsServiceobjectivesSettingstockinglevelssothatthereisonlyaspecifiedprobabilityofrunningoutofstockCostobjectivesBalancingconflictingcoststofindthemosteconomicalreplenishmentquantitiesandtimingCR(2004)PrenticeHall,Inc.199.4.1產(chǎn)產(chǎn)品品的的現(xiàn)現(xiàn)貨貨供供應(yīng)應(yīng)比比率率服務(wù)務(wù)水水平平=1-每每年年產(chǎn)產(chǎn)品品缺缺貨貨件件數(shù)數(shù)的的期期望望值值/年年需需求求總總量量20CR(2004)PrenticeHall,Inc.采購購成成本本Procurementcosts準(zhǔn)備訂單的成成本Costofpreparingtheorder訂單傳輸成本本Costofordertransmission產(chǎn)品安裝成本本Costofproductionsetupifappropriate接受地物料搬搬運(yùn)或加工成成本Costofmaterialshandlingorprocessingatthe receivingdock商品價(jià)格Priceofthegoods9.4.2庫庫存管理相關(guān)關(guān)成本CostsRelevanttoInventoryManagement21CR(2004)PrenticeHall,Inc.RelevantCosts(Cont’’d)采購成本ProcurementcostsCostofpreparingtheorderCostofordertransmissionCostofproductionsetupifappropriateCostofmaterialshandlingorprocessingatthereceivingdockPriceofthegoods22CR(2004)PrenticeHall,Inc.庫存持有成本本Carryingcosts空間成本。庫庫存成本隨時(shí)時(shí)間推移Costforholdingtheinventoryovertime資金成本。庫存服務(wù)成本本庫存風(fēng)險(xiǎn)成本本23CR(2004)PrenticeHall,Inc.9.4.2庫庫存管理相關(guān)關(guān)成本CostsRelevanttoInventoryManagement庫存持有成本本CarryingcostsCostforholdingtheinventoryovertimeTheprimarycostisthecostofmoneytiedupininventory,butalsoincludesobsolescence（報(bào)廢）,insurance,personalpropertytaxes,andstoragecostsTypically,costsrangefromthecostofshorttermcapitaltoabout40%/year.Theaverageisabout 25%/yearoftheitemvalueininventory.24CR(2004)PrenticeHall,Inc.RelevantCosts(Cont’’d)缺貨成本Out-of-stockcosts銷售損失成本本Lostsalescost利潤(rùn)損失Profitimmediatelyforegone商譽(yù)損失Futureprofitsforegonethroughlossofgoodwill缺貨成本Backordercost額外訂單處理理費(fèi)用Costsofextraorderhandling額外的運(yùn)輸和和處理費(fèi)用Additionaltransportationandhandlingcosts可能的安裝費(fèi)費(fèi)用Possiblyadditionalsetupcosts25Inventory’sConflictingCostPatternsCost補(bǔ)給量Replenishmentquantity缺貨成本Stockoutcost采購成本Procurementcost庫存持有成本本Carryingcost總成本Totalcost最低訂貨成本本MinimumcostreorderquantityCR(2004)PrenticeHall,Inc.9-1626術(shù)語匯編GlossaryofTermssold

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n)('nsLTSLTCzxsrzMAXTROPQPEspksCISdDLT'zd=====================279.5推動(dòng)式式庫存管理1.通過預(yù)測(cè)測(cè)或其他手段段確定從現(xiàn)在在到下一次生生產(chǎn)或采購期期間的需求量量2.找出每個(gè)個(gè)存儲(chǔ)點(diǎn)現(xiàn)有有的庫存量3.設(shè)定每個(gè)個(gè)存儲(chǔ)點(diǎn)庫存存的現(xiàn)貨供應(yīng)應(yīng)水平4.計(jì)算總需需求5.計(jì)算凈需需求6.在平均需需求速率的基基礎(chǔ)上，將超超過總凈需求求的部分分配配到各存儲(chǔ)點(diǎn)點(diǎn)7.在凈需求求加上分配的的超量部分得得到需分配到到每個(gè)存儲(chǔ)點(diǎn)點(diǎn)的貨物總量量289.6基本的的拉動(dòng)式庫存存管理（1）需求是是一次性的、、高季度性的的或持續(xù)性的的情況（2）訂貨程程序在某一庫庫存水平上啟啟動(dòng)或由庫存存盤點(diǎn)程序啟啟動(dòng)（3）需求和和補(bǔ)貨提前期期存在不同程程度不確定性性的情況29CR(2004)PrenticeHall,Inc.9.6.1一一次性訂貨量量SingleOrderPurchasingMakeaone-timepurchaseofanitem.Howmuchtoorder?Procedure:平衡利潤(rùn)增加加額與損失增增加額利潤(rùn)=單位價(jià)格-單單位成本損失=單位成本-單單位殘值如果考慮一定定量產(chǎn)品被售售出的概率CPn，預(yù)期收益和和預(yù)期損失在在以下點(diǎn)得到到平衡CPnx損失=(1-CPn)x利潤(rùn)orCPn=利潤(rùn)/(利潤(rùn)+損失)CPn代表至至多售出n個(gè)個(gè)單位產(chǎn)品的的累積概率Dailystockingofnewspapersinvendingmachinesisagoodexample9-1830CR(2004)PrenticeHall,Inc.9.6.1一一次性訂貨量量SingleOrderPurchasingMakeaone-timepurchaseofanitem.Howmuchtoorder?Procedure:Balanceincrementalprofitagainstincrementalloss.Profit=PriceperunitCostperunitLoss=CostperunitSalvagevalueperunitIfCPnisprobabilityofnunitsbeingsold,thenCPnxLoss=(1CPn)xProfitorCPn=Profit/(Profit+Loss)Now,increaseorderquantityuntilCPnjustmatchescumulativeprobabilityofsellingadditionalunits.Dailystockingofnewspapersinvendingmachinesisagoodexample9-1831CR(2004)PrenticeHall,Inc.SingleOrderPurchasing(Cont’’d)ExampleAclothingitemispurchasedforaseasonalsale.Itcosts$35,butithasasalepriceof$50.Aftertheseasonisover,itismarkeddownby50%toclearthemerchandise.Theestimatedquantitiestobesoldare:Numberofitems,nProbabilityofsellingexactlynitemsCumulativeprobability100.150.15150.200.35200.300.65250.200.85300.100.95350.051.001.009-1932CR(2004)PrenticeHall,Inc.9.6.1一次次性訂訂貨量量SingleOrderPurchasing(Cont’d)SolutionProfit=$50-35=$15Loss=$35-(0.5)(50)=$10CPn=15/(15+10)=0.60CPnisbetween15and20items,roundupandorder20items.339.6.2重復(fù)復(fù)訂貨貨量1.即即刻補(bǔ)補(bǔ)貨TC——每年年總的的相關(guān)關(guān)成本本（美美元））Q—補(bǔ)補(bǔ)充存存貨的的訂單單批量量（件件）D—對(duì)對(duì)庫存存產(chǎn)品品的年年需求求量（（件））S—采采購成成本（（美元元/訂訂單））C—庫庫存產(chǎn)產(chǎn)品的的價(jià)值值（美美元/件））I—庫庫存持持有成成本占占產(chǎn)品品價(jià)值值的比比例（（%/年））Developasimplecontrolsystembyfindingthereplenishmentquantity(Q)andthereorderpoint(ROP).Therelevanttotalcostis:總成本本=采采購成成本和和庫存存成本本注:需求和和提前前期確確定—周期性性的庫庫存管管理9-21349.6.2重復(fù)復(fù)訂貨貨量1.即即刻補(bǔ)補(bǔ)貨TC——每年年總的的相關(guān)關(guān)成本本（美美元））Q—補(bǔ)補(bǔ)充存存貨的的訂單單批量量（件件）D—對(duì)對(duì)庫存存產(chǎn)品品的年年需求求量（（件））S—采采購成成本（（美元元/訂訂單））C—庫庫存產(chǎn)產(chǎn)品的的價(jià)值值（美美元/件））I—庫庫存持持有成成本占占產(chǎn)品品價(jià)值值的比比例（（%/年））Developasimplecontrolsystembyfindingthereplenishmentquantity(Q)andthereorderpoint(ROP).Therelevanttotalcostis:總成本本=采采購成成本和和庫存存成本本Note:Nouncertaintyindemandorleadtime—manageregular(cycle)stockonly9-2135CR(2004)PrenticeHall,Inc.0TimeLeadtimeLeadtimeOrderPlacedOrderPlacedOrderReceivedOrderReceivedInventoryLevelReorderpoint,RQReorderPointMethodUnderCertaintyforaSingleItemQuantityon-handpluson-order9-22369.6.2重重復(fù)復(fù)訂訂貨貨量量Given:d=50units/weekI=10%/yearS=$10/orderC=$5/unitLT=3weeksNote:Nouncertaintyindemandorleadtime——manageregular(cycle)stockonly9-212.有有提提前前期期的的補(bǔ)補(bǔ)貨貨37CR(2004)PrenticeHall,Inc.Usingdifferentialcalculus,theoptimalvalueforQwillbe:Thereorderpointis:ROP=d(LT)=3(50)=150unitsFamousEOQformulaRuleWhentheinventoryleveldropsto150units(ROP)thenreorder322units(Q*).9-23383.對(duì)對(duì)不不準(zhǔn)準(zhǔn)確確數(shù)數(shù)據(jù)據(jù)的的敏敏感感性性盡管管我我們們不不一一定定總總能能知知道道需需求求和和成成本本的的確確切切水水平平，，經(jīng)經(jīng)濟(jì)濟(jì)訂訂貨貨批批量量的的計(jì)計(jì)算算對(duì)對(duì)估估計(jì)計(jì)錯(cuò)錯(cuò)誤誤的的數(shù)數(shù)據(jù)據(jù)并并不不敏敏感感。。394.非非即即刻刻補(bǔ)補(bǔ)貨貨EOQ模模型型中中有有一一個(gè)個(gè)基基本本假假設(shè)設(shè)，，即即任任何何訂訂貨貨批批量量都都可可以以及及時(shí)時(shí)補(bǔ)補(bǔ)進(jìn)進(jìn)。。在在有有些些制制造造和和再再供供應(yīng)應(yīng)環(huán)環(huán)節(jié)節(jié)中中，，生生產(chǎn)產(chǎn)要要持持續(xù)續(xù)一一定定時(shí)時(shí)間間，，并并且且可可能能和和需需求求同同步步進(jìn)進(jìn)行行。。p是是生生產(chǎn)產(chǎn)速速率率，，d是是需需求求速速率率40CR(2004)PrenticeHall,Inc.9.7高高級(jí)級(jí)拉拉動(dòng)動(dòng)式式庫庫存存管管理理9.7.1需需求求不不確確定定下下的的再再訂訂貨貨點(diǎn)點(diǎn)模模型型1.計(jì)計(jì)算算Q*和和ROPGoodmethodforproducts:OfhighvalueThatarepurchasedfromonevendororplantHavingfeweconomiesofscaleinproduction,purchasing,ortransportation9-24FindQ*andROP41CR(2004)PrenticeHall,Inc.9.7高高級(jí)拉動(dòng)動(dòng)式庫存存管理9.7.1需求求不確定定下的再再訂貨點(diǎn)點(diǎn)模型Given:d=50units/weekC=$5/unitsd=10units/weekLT=3weeksI=10%/yearP=99%duringleadtimeS=$10/orderFindQ*andROPFromtheEOQformulaGoodmethodforproducts:OfhighvalueThatarepurchasedfromonevendororplantHavingfeweconomiesofscaleinproduction,purchasing,ortransportation9-2442CR(2004)PrenticeHall,Inc.ReorderPointControlforaSingleItemROPQuantityonhand0QQReceiveorderPlaceorderStockoutLTTimeLTDDLTP9-2543CR(2004)PrenticeHall,Inc.ROPQ0InventorylevelLTLTTimeSafetystockReorderPointControlforaSingleItemActualonhandQuantityonhand+onorderbackordersQuantityforcontrol9-2644Weeklydemandisnormallydistributedwithameanofd=100andastandarddeviationofsd=10Leadtimeis3weeksReorderPointControl(Cont’d)Findingthereorderpointrequiresanunderstandingofthedemand-during-lead-timedistributionsd=10d=100sd=10d=100sd=10d=100++=Week3Week2Week1zPDDLTX=300ROPS’=17.39-2745CR(2004)PrenticeHall,Inc.ReorderPointControl(Cont’d)where2.33isthenormaldeviateataprobabilityof0.01takenfromanormaldistributiontable.462.平均庫庫存成本平均庫存=經(jīng)常性庫庫存+安全全庫存A/L=Q/2+z(s'd)在前例中，，平均庫存=322/2+2.33*17.32=201(個(gè)）47ReorderPointControl(Cont’d)3.總相關(guān)關(guān)成本TotalrelevantcostThetotalrelevantcostequationisnowextendedtoincludethecostsofsafetystockaswellasout-of-stock.Theout-of-stockcost(k)is$2/unit.Thepricetermisdropped.Hence,whereE(z)=0.0034fromaunitnormallosstableatazvalueof2.339-29484.服務(wù)水水平服務(wù)水平=1-每年年產(chǎn)品缺貨貨件數(shù)的期期望值/年年需求總量量49CR(2004)PrenticeHall,Inc.9.7.2缺貨成本本已知情況況下的再訂訂貨成本W(wǎng)ithknownstockoutcostsk如果缺貨成成本已知，，就沒必要要規(guī)定客戶戶服務(wù)水平平了，可以以將服務(wù)和和成本的最最佳平衡點(diǎn)點(diǎn)計(jì)算出來來?？捎梅捶磸?fù)迭代的的方法1利用基本EOQ公式式得出訂貨貨量的近似似值SolveinitiallyforQ2通過下式計(jì)計(jì)算提前期期內(nèi)現(xiàn)貨供供應(yīng)的概率率UsingQ,find如果缺貨允允許Ifbackorderingisallowedor如果銷售出出現(xiàn)損失Ifsalesarelost50CR(2004)PrenticeHall,Inc.ReorderPointControl(Cont’d)3計(jì)算Q的修修正值UsingP,findrevisedQ4重復(fù)2,3步直到P和Q不再再變化Repeatsteps2and3untilnofurtherchange5計(jì)算ROP和其他所所需的統(tǒng)計(jì)計(jì)值ComputeROPandotherstatistics51CR(2004)PrenticeHall,Inc.ReorderPointControl(Cont’d)ExampleGiven:每月需求預(yù)預(yù)測(cè),d11,107units預(yù)測(cè)標(biāo)準(zhǔn)差差,sd3,099units補(bǔ)貨提前期期,LT1.5months產(chǎn)品價(jià)值,C$0.11/unit處理訂單的的成本,S$10/order庫存持有成成本,I20%/year缺貨成本,k$0.01/unitBackorderingisallowed允許缺貨FindoptimalQandP52CR(2004)PrenticeHall,Inc.ReorderPointControl(Cont’d)ExampleGiven:Monthlydemandforecast,d11,107unitsStd.errorofforecast.,sd3,099unitsReplenishmentlead-time,LT1.5months

Itemvalue,C$0.11/unit

Costforprocessingvendororder,S$10/order

Carryingcost,I20%/yearStockoutcost,k$0.01/unitBackorderingisallowedFindoptimalQandP53CR(2004)PrenticeHall,Inc.ReorderPointControl(Cont’d)SolutionEstimateQEstimatePReviseQFindAppA,z@0.82=0.92andfromAppB,E(0.92)=0.0968Forthesedata,s'dwaspreviouslycalculatedas3,795units54CR(2004)PrenticeHall,Inc.ReorderPointControl(Cont’d)RevisePNow,z@0.79=0.81andE(0.81)=0.118155CR(2004)PrenticeHall,Inc.ReorderPointControl(Cont’d)ReviseQContinuetoreviseQandPuntilnofurtherchangeoccurs.P=78%andQ=13,395units.NoteAlthoughthein-stockprobabilityduringtheleadtimeis78%,theactualservicelevelisSL=96%569.7.3需求和提提前期不確確定條件下下的再訂貨貨點(diǎn)法ReorderpointcontrolwithdemandandleadtimeuncertaintiesCaution:Canresultinveryhighsafetystocklevelswhenlead-timevariabilityishigh9-37在需求和提提前期不確確定的情況況下找到正正態(tài)分布的的標(biāo)準(zhǔn)差s'd。這可以通過過將需求波波動(dòng)和提前前期波動(dòng)累累加獲得。。由此s'd得到修正公公式sLT是提前期的的標(biāo)準(zhǔn)差57CR(2004)PrenticeHall,Inc.SupplyChainExample(Cont’d)DistributorOutboundtransportInboundtransportPoolpointSupplierXspp==1012,.Xsii==4102,.Xsoo==20252,.ProcessingtimeTransporttimeTransporttime供應(yīng)商內(nèi)向運(yùn)輸集散地加工時(shí)間供應(yīng)商58CR(2004)PrenticeHall,Inc.PullMethods(Cont’d)SupplychainexampleSupposethatinventoryistobemaintainedonadistributor’sshelfforanitemwhosedemandisforecastedtobed=100unitsperdayandsd=10unitsperday.Areorderpointisthemethodofinventorycontrol.Thesupplychannelisshowninthediagram.Determinetheaverageinventorytobeheldatthedistributorwherewehave:I=10%/yearC=$5/unitS=$10/orderP=0.99duringleadtime59CR(2004)PrenticeHall,Inc.SupplyChainExample(Cont’d)SolutionThereorderpointinventorytheoryapplies.However,determiningthestatisticsofthedemand-during-lead-timedistributionrequirestakingthelead-timefortheentirechannelintoaccount.Recall,60CR(2004)PrenticeHall,Inc.SupplyChainExample(Cont’d)AverageleadtimeNowand61CR(2004)PrenticeHall,Inc.9.7.4需求不確確定條件下下的定期盤盤點(diǎn)模型Periodicreviewcontrolwithdemanduncertainty按預(yù)先確定定的周期（（T)核查查某種產(chǎn)品品的庫存。。盤點(diǎn)后的的訂貨量就就是最大值值（M)與與盤點(diǎn)時(shí)所所持有的庫庫存量之差差。因此可可以通過設(shè)設(shè)定T*和和M*控制制庫存。Given:d=50units/weekC=$5/unitsd=10units/weekLT=3weeksI=10%/yearP=0.99S=$10/orderk=$2/unitGoodmethodforproducts:OflowvalueThatarepurchasedfromthesamevendorHavingeconomiesofscaleinproduction,purchasing,andtransportation9-38629-39Q1StocklevelreviewedTTLTLTOrderreceivedQ2Mq0QuantityonhandTimeM=maximumlevel最高庫存M-q=replenishmentquantity補(bǔ)貨量LT=leadtime提前期T=reviewinterval盤點(diǎn)周期q=quantityonhand持有庫存量Qi=orderquantity訂購量~單一產(chǎn)品定期期盤點(diǎn)PeriodicControlforaSingleItem盤點(diǎn)時(shí)庫存63CR(2004)PrenticeHall,Inc.EstimateQ*fromtheEOQformulaasifunderdemandcertaintyconditions.RecallthatthisisQ*=322units.Now,T*=Q*/d=322/50=6.4weeksConstructthedemand-during-lead-time-plus-order-cycle-timedistribution.TisorderreviewtimePeriodicReview(Cont’d)64CR(2004)PrenticeHall,Inc.PeriodicReview(Cont’d)PDD(T*+LT)X=d(T*+LT)MAXs′Z(s′)65PeriodicReview(Cont’’d)whereFindMAXMAX=d(T*+LT)+z(s’)=50(6.4+3)+2.33(30.66)=470+71.44=541unitsRuleReviewtheinventoryevery6.4weeksandplaceanorderforthedifferencebetweentheMAXlevelof541unitsandthequantityonhand+quantityonorder––backorders.CR(2004)PrenticeHall,Inc.9-4266CR(2004)PrenticeHall,Inc.PeriodicReview(Cont’’d)總相相關(guān)關(guān)成成本本Thetotalrelevantcostforthisdesignis:TC=DS/Q+ICQ/2+ICr+ks’’(D/Q)E(z)=2600(10)/322+(.10)(5)(322/2)+(.10)(5)(71)+2(30.66)(2600/322)(.0034)=$198Note與再再訂訂貨貨的的點(diǎn)點(diǎn)的的方方法法比比（（$182）），，定定期期盤盤點(diǎn)點(diǎn)因因?yàn)闉榘舶踩坛潭榷雀吒撸?，所所以以成成本本相相?duì)對(duì)較較高高（（$198））67PullMethods(Cont’’d)9-4468PullMethods(Cont’’d)聯(lián)合合訂訂貨貨聯(lián)合合訂訂貨貨的的庫庫存存管管理理包包括括確確定定聯(lián)聯(lián)合合訂訂貨貨的的所所有有產(chǎn)產(chǎn)品品的的共共同同盤盤點(diǎn)點(diǎn)時(shí)時(shí)間間，，然然后后根根據(jù)據(jù)其其成成本本和和服服務(wù)務(wù)水水平平求求出出每每種種產(chǎn)產(chǎn)品品的的最最高高庫庫存存水水平平。。whereO=commonprocurementcost,$/order訂購購采采購購的的聯(lián)聯(lián)合合成成本本下標(biāo)標(biāo)i代代表表某某種種特特定定產(chǎn)產(chǎn)品品Note:Q*=T*xdCR(2004)PrenticeHall,Inc.9-4969每種種產(chǎn)產(chǎn)品品的的最最高高庫庫存存水水平平總相相關(guān)關(guān)成成本本=訂訂購購成成本本+經(jīng)經(jīng)營(yíng)營(yíng)性性庫庫存存持持有有成成本本+安安全全庫庫存存持持有有成成本本+缺缺貨貨成成本本70CR(2004)PrenticeHall,Inc.JointOrderingExampleItemABAveragedailydemand(d)3075unitsDemandstd.dev.(sd)810unitsAverageleadtime(LT)1414daysAnnualcarryingcost(I)2525%Procurementcost(S)3020$/orderwithcommoncost(O)80$/orderIn-stockprobability(P)8092%Productvalue(C)170200$/unitOut-of-stockcost(k)2545$/unitSellingdaysperyear365365daysGiven71CR(2004)PrenticeHall,Inc.JointOrderingExample(Cont’d)FindcommonreviewtimeFindtargetquantity(MAX)foritemAthenz@80%=0.8472JointOrderingExample(Cont’d)whichhasanaverageinventoryofFindtargetquantity(MAX)foritemBthenforz@90%=1.41whichhasanaverageinventoryofCR(2004)PrenticeHall,Inc.73CR(2004)PrenticeHall,Inc.9.7.5實(shí)用用拉動(dòng)動(dòng)式庫庫存管管理方方法PullMethods(Cont’d)1.最最低-最高高庫存存管理理法TheMin-Maxvariant當(dāng)庫存存水平平達(dá)到到再訂訂貨點(diǎn)點(diǎn)時(shí)，，要訂訂購的的貨物物數(shù)量量就是是目標(biāo)標(biāo)庫存存量M（最最高點(diǎn)點(diǎn)）與與所持持庫存存量q之差差。74CR(2004)PrenticeHall,Inc.Min-MaxInventoryControl~Q1Q2Q*ROPqLTLTTimeQuantityonhandMAddincrementROPqtoordersize9-5475CR(2004)PrenticeHall,Inc.PullMethods(Cont’d)TheT,R,MvariantThisisacombinationofthemin-maxandtheperiodicreviewsystems.Thestocklevelsarereviewedperiodically,butcontrolthereleaseofthereplenishmentorderbywhetherthereorderpointisreached.Thismethodisusefulwheredemandislow,suchthatsmallquantitiesmightbereleasedunderaperiodicreviewmethod.76CR(2004)PrenticeHall,Inc.PullMethods(Cont’d)T,R,MvariantLTLTTTTimeRqInventorylevelT=reviewtimeR=reorderpointM–Q=replenishmentquantity補(bǔ)給量Q1Q2InventorynotbelowR,sodon’’tplaceanorder9-5677CR(2004)PrenticeHall,Inc.PullMethods(Cont’d)2.按需存存儲(chǔ)Stocktodemand(aperiodicreviewmethod)對(duì)某種產(chǎn)品品的需求速速率進(jìn)行預(yù)預(yù)測(cè)。預(yù)測(cè)測(cè)值乘以一一個(gè)代表盤盤點(diǎn)周期、、補(bǔ)貨提前前期，以及及包含需求求預(yù)測(cè)和提提前期不確確定性的時(shí)時(shí)間增量的的因子，就就得到目標(biāo)標(biāo)值。預(yù)測(cè)測(cè)時(shí)還要記記錄所持庫庫存量，而而訂購量就就等于目標(biāo)標(biāo)值減去所所持庫存量量。按需存存儲(chǔ)庫存控控制法實(shí)際際上是一種種定期盤點(diǎn)點(diǎn)的方法。。78CR(2004)PrenticeHall,Inc.PullMethods(Cont’d)3.多產(chǎn)品品、多地點(diǎn)點(diǎn)的庫存管管理Multipleitem,multiple-locationcontrolThetheorythathasbeendiscussedpreviouslyisusefulwhendesigninginventorycontrolsystemsforthepracticalproblemofcontrollingmanyitemsatmanylocations.Considerhowaspecialtychemicalcompanydesignedsuchapracticalsystem.TASO（訂單積累累時(shí)間）isthetimetoaccumulateastockorder(truckload)forallitemsinwarehouse.79Q1StockorderTASOTASOLTOrderreceivedLTQ2M0QuantityonhandTime

M=maximumlevelTASO=timetoaccumulatestockorder

Qi=orderquantityLT=leadtimeTASO~~Q3Multiple-Item,Multiple-LocationControlCR(2004)PrenticeHall,Inc.9-6080CustomerServiceLevelForindividualitemsTheservicelevel(stockavailability)actuallyachievedbyinventorycontrolmethodsisnotbestrepresentedbytheprobability(P)ofastockoutduringtheleadtime.Itismoreaccuratetocomputeitasfollows.Usingdatafromthereorderpointunderuncertaintyexample,theservicelevelwouldbe:Note:HigherthanPCR(2004)PrenticeHall,Inc.9-6181CR(2004)PrenticeHall,Inc.CustomerServiceLevel(Cont’d)ThisactuallevelishigherthanP=0.99thatwasusedtosettheinventorylevel.Thereasonisthatthereareperiodsoftimewhenthestocklevelisabovethereorderpointandthereisnoriskofbeingoutofstock.Methodsfordefiningstockavailabilityinclude:ProbabilityoffillingallitemdemandProbabilityoffillinganordercompletelyProbabilityoffillingapercentofallitemdemandWeightedaverageofitemsfilledonanorder(fillrate)82CR(2004)PrenticeHall,Inc.CustomerServiceLevel(Cont’d)FormultipleitemsonthesameorderIfallitemsonanorderhavethesameservicelevel,whatistheprobabilityoffillingtheordercomplete?Theservicelevelformultipleitemsisthecombinationoftheindividualitemserv