物流系统建模课件

第三章物流系统建模

税文兵交通工程学院物流系2013.11第三章物流系统建模税文兵Contents案例1建模的一般理论23物流系统模型Contents案例1建模的一般理论23物流系统模型2案例SheridanTechnologies,Inc.isanindustrialproductscompanyoperatingthreeplantsintheUnitedStates,plantsaretriangles,distributioncentersarecircles,andcustomergroupsaresquares.TheplantsshipfinishedproductsinTruckload(TL)quantitiestofiveDCs,ThecompanyshipsviaLess-Than-Truckload(LTL)commoncarriersoutoftheDCs,typicallyweeklyforeachcustomer.案例SheridanTechnologies,Inc.3Definitionandmainactivitiesof案例

Linksdepictthecurrentassignmentofcustomerstodistributioncenters.Thecurrentsourcingassignmentshavedevelopedhistoricallyoverseveralyears,andhavebeeninfluencedbyvariousfactorsincludingworkloadbalance,companygrowth,politics,andhistoricalpartnerships.Definitionandmainactivities4案例ThenewVicePresidentofLogisticsatSheridanTechnologieshasinitiatedastudyofthecompany’slogisticssupplychainoperations,andformedaprojectteamtoanalyzethefollowing：

顾客是否从正确的DCs获得产品?

公司是否应该考虑改变现有的DCs和顾客分配策略？应该怎样改变？Underthecompany’scurrentsinglesourcingdistributionstrategy,whatistheoptimalnumberandlocationofDCsthatminimizeslogisticscosts?Beforegeneratingandanalyzinganychangestothecurrentsystem,theprojectteamfirstwantstocreateasimplifiedmodelrepresentationandensurethemodelaccuratelyrepresentstheactuallogisticssystem.Asimplifiedmodelisdesirabletobetterunderstandthesignificantelementsandcostsofthesupplychainandtoallowalternativestoberapidlygeneratedandeasilyinterpreted.案例ThenewVicePresidentofLo5案例Oneyear’shistoricalshippinginformationwillbeanalyzedtocaptureanymonthlyorquarterlyseasonalvariationsincustomerorderingpatterns.Thecompany’smainframecomputerholdsover100,000freightbillspaidtotruckingcompanieslastyear,sotheteamdecidestosimplifytheanalysisbycalculatingtheaverageorderquantityandorderfrequencybyeachregion.第一步：Aggregatehistoricalshipmentstoestimatefuturedemand第二步：运输成本的计算和分配对于从DCs到顾客的LTLcost，使用LTLfreightratingtables.（单位数量的物品的运输费率）对于从工厂到DCs的TLcosts，使用theaverageorderquantitybyproductfamily分配每一个顾客在TL成本中所占的比例。.Usingaverageorderquantities,theestimatedannualLTLandTLcostsareabout10.5milliondollarsandabout2.1milliondollars,respectively.案例Oneyear’shistoricalshippi6案例Theratecontoursfor1000-2000poundshipmentsoriginatingfromthecompany’sRichardson,TexasDC.LTL费率一般会随着距离的增加而增大，但也有例外。Forexample,truckingratesaredisproportionatelymoreexpensiveshippingtoFlorida,becauseFloridaisaconsumingstateandtrucksmustoftenleavethestateempty.案例Theratecontoursfor1000-27案例第三步：建立模型获得新的顾客与DCs的分配方案模型的目标：totaltransportationcosts最小ThebestassignmentforeachmarketissimplytheDCdeliveringtheaveragemarketshipmentatminimaltotaltransportationcost.决策内容：

DCs与顾客最优分配关系模型的求解结果：ThetotalannualLTLandTLcostsforthissolutionareroughly10millionand2.1milliondollarsrespectively,asavingsofroughly

500thousanddollarsannually.TheteamnotestheinfluenceoftheLTLratestructureandinboundTLcostsonmarketassignments-obviouslytheDCnearestamarketisnotalwaysthebest.案例第三步：建立模型获得新的顾客与DCs的分配方案模型的目标8案例Optimalsinglesourcingassignmentusingthecurrentsetofdistributioncenters.案例Optimalsinglesourcingassi9案例第四步：研究合并现有配送中心的效果AsthereareonlyfiveDCsitiseasytoenumeratetherespectivesolutionswitheachDCclosed.Totalannualcosts(inmillions)witheachDCclosed,respectively.ClosingColumbusincreasestransportationcostsbytheleastamount.Ifthecosttooperatethisfacilityisgreaterthan$400,000annually,thenclosingthisDCreducestotalcosts.案例第四步：研究合并现有配送中心的效果Astherear10案例OptimalcustomerallocationwiththeColumbusDCclosed.AtlantaandAllentownpickupmostofthereassignedshippingvolume.案例Optimalcustomerallocation11案例第五步：研究重新构建配送中心的效果Byvisualinspectionofcustomergeographicalproximityandaverageordervolumes,theteamselects25DClocationstobeanalyzedascandidatesites.EachDCisestimatedtocost$200,000annuallytooperate,independentoftheactualshipmentvolumehandledbytheDC.Lastly,theteamdevelopsamixed-integermathematicaloptimizationformulationwithopen/closeintegervariablesrepresentingopening/closingcandidateDCs.Thetotaltransportationcostofthissolutionisroughly$10millionannually,asavingsofover$2millionannuallycomparedtoeitherthecurrentsupplychainconfigurationorthebestsinglesourcingsolution.案例第五步：研究重新构建配送中心的效果Byvisuali12案例Optimalnumberandlocationofdistributioncenters,andtheoptimalallocationofcustomerstoDCs.Thisconfigurationofthesupplychainreducesannualcostsbyover2milliondollars.案例Optimalnumberandlocation13系统建模系统模型定义

对一个系统某一方面本质属性的描述，以某种确定的形式（如文字、符号、图表、实物、数学公式等）提供关于该系统的某一方面的知识。

★系统模型是对现实系统的描述、模仿或抽象。★对同一个系统，根据不同的研究目的，可以

建立不同的系统模型。系统建模系统模型定义★系统模型是对现实系统的14系统建模

系统模型来源于实际系统，反映的是实际系统的主要特征，但它又高于实际系统，能反映同类问题的共性，是对所要研究问题的抽象。特征系统建模特征15★是对现实系统的抽象或模仿；

★是由反映系统本质或特征的主要要素构成的；

★集中体现了这些主要要素之间的关系。系统建模系统模型★是对现实系统的抽象或模仿；系统建模系统模型16系统建模系统模型的分类系统的种类繁多，作为系统的描述——系统模型的种类同样也是多种多样。从不同的角度观察，可以得出多种不同的分类方法。

系统建模系统模型的分类系统的种类繁多，作为系统的描述——系统17系统建模按建模材料的不同抽象模型实物模型系统建模按建模材料的不同抽实18系统建模按与实体系统的关系形象模型数学模型相似模型系统建模按与实体系统的关系形数相19系统建模按与时间的依赖关系动态模型静态模型系统建模按与时间的依赖关系动静20系统建模按模型的用途结构模型优化模型评价模型系统建模按模型的用途结优评21系统建模

系统模型的分类与特征对比研究的速度、灵活性、抽象性：依次增加现实性、建模时间、建模费用：依次减少特征对比现实系统实体模型图表模型逻辑模型解析模型比例模型相似模型网络模型物理模型数学模型文字模型系统建模系统模型的分类与特征对比研究的速度、灵活性、抽象性22系统建模实体模型就是现实系统本身，当系统的大小刚好适合研究而且又不存在危险时，可以将系统本身作为研究模型。如产品质量检验中的抽样模型就属于实体模型。。实体模型系统建模实体模型就是现实系统本身，实体模型23系统建模比例模型，是对现实系统的放大或缩小，使之适合于研究。比例模型系统建模比例模型24系统建模相似模型根据相似原理，利用一种系统去代替另一种系统，称相似模型。例如用电路系统代替机械系统、热力学系统进行研究，则电路系统就是后二者的相似模型。系统建模相似模型25系统建模文字模型在物理模型和数学模型都很难建立时，有时不得不用文字符号来描述系统研究的结果，如技术报告、说明书等就属于文字模型。系统建模文字模型26系统建模网络模型用网络图来描述系统的组成要素以及要素之间的相互关系（包括逻辑关系与数学关系）。系统建模网络模型27系统建模图表模型：指用图像和表格形式描述的模型，图像与表格形式二者可以互相转化，这里说的图像是指坐标系中的曲线、曲面或点等几何图形。图表模型系统建模图表模型28系统建模逻辑模型：指用方框图、程序单、模拟机排题图等形式表示系统要素逻辑关系的模型。逻辑模型系统建模逻辑模型29系统建模解析模型：指用数学方程式表示系统某些特性的模型。解析模型系统建模解析模型30系统建模无论是在自然科学、工程技术、还是社会科学领域，没有定量分析，就没有科学的预测与决策，就会造成决策失误数学模型是定量分析的基础★系统工程中经常使用数学模型来分析问题；★数学模型具有良好的可变性和适应性，便于使用计算机，便于快速分析。

所谓系统建模，大多数情况下都是指建立系统的数学模型。系统建模无论是在自然科学、工程技术、还是社会科学领域，没有定31系统建模建立系统模型的基本原则

准确性可靠性

简明性

实用性反馈性系统建模建立系统模型的基本原则准确性可靠性简明性实用性32系统建模统计分析推理分析人工模拟系统建模方法系统建模统计分析推理分析人工模拟系统33系统建模

对于问题明确、内部结构和特性十分清楚的系统，可以利用已知的定律和定理，经过一定的分析和推理，建立系统模型。推理分析系统建模推理分析34系统建模

对于那些内部结构和特性不很清楚，且又不能直接进行实验观察的系统（大多数的物流系统及其他非工程系统就属于此类），可以采用数据收集和统计分析的方法，建立系统模型。统计分析系统建模统计分析35系统建模

当系统结构复杂，性质不太明确，缺乏足够的数据、且无法进行实验观察时，可借助一些人工方法，如模拟仿真法或启发式方法，逐步建立物流系统模型。人工模拟系统建模人工模拟36系统建模弄清问题，掌握真实情况；搜集资料；确定因素之间的关系；构造模型；求解模型；检验模型的正确性。系统建模的步骤系统建模弄清问题，掌握真实情况；系统建模的步骤37物流系统建模物流系统设计和运营中面临的问题：物流系统建模物流系统设计和运营中面临的问题：38物流系统建模将这些问题进行归类，形成了各种规划物流系统建模将这些问题进行归类，形成了各种规划39物流系统建模SupplyChainPlanningincludesthelocation,sizing,andconfigurationofplantsanddistributioncenters,theconfigurationofshippinglanesandsourcingassignments,theaggregateallocationofproductionresources,andcustomerprofitabilityandserviceissues.ShipmentPlanningistheroutingandschedulingofshipmentsthroughthesupplychain,includingfreightconsolidationandtransportationmodeselection.TransportationSystemsPlanningincludesthelocation,sizing,andconfigurationofthetransportationinfrastructure,includingfleetsizingandnetworkalignment.物流系统建模SupplyChainPlanningin40物流系统建模VehicleRouting&Schedulingincludestheroutingandschedulingofdrivers,vehicles,trailers,etc.Otherapplicationsincludedynamicdispatching,customerzonealignment,andfrequencyofdeliveryquestions.Warehousingincludesthelayoutdesignandstorage/pickingoperationsofdistributioncenters.物流系统建模VehicleRouting&Schedu41物流系统建模在用模型来回答这些具体的物流问题之前，必须先确定特定的物流战略或策略。Asanexample,acommondistributionstrategyistoshipallproductstoacustomerfromasingledistributioncenter(DC).AnothercommonstrategyistoshiptoacustomerfrommultipleDCs.ChoosingthebestDC(s)toservethecustomerisaspecificlogisticsdecisionineitherstrategy,buttheallowablechoicesareshapedbytherespectivestrategies.物流系统建模在用模型来回答这些具体的物流问题之前，必须先确定42物流系统建模现代物流战略物流系统建模现代物流战略43现代物流战略Just-in-TimeLogisticsIfweknewpreciselywhere,when,andhowmuchmaterialisneededateachstageofalogisticssupplychain,goodscouldbemovedthroughthesupplychainjust-in-time(JIT)forusebythenextprocess,withoutaneedtobuildupinventories.Thusproductreplenishmentsare“pulled”allthewaythroughthesupplychainfromthepointofsaleHistorically,productshavebeen“pushed”throughasupplychainbasedonforecastsoffuturecustomerdemand.Thisstrategyallowsscaleeconomiesinthepurchasingofrawmaterials,manufacturingbatchruns,andtransportationshipments.However,costlyinventoriesbuilduptoprotecterrorsinforecasts,andthelogisticssystemisslow-movingandinflexibletorapidmarketchanges.现代物流战略Just-in-TimeLogisticsIf44现代物流战略Thedesignofasupplychainisalsoimpactedasthereislessemphasisonproductstorage.Shipmentplanningisfundamentallyaffectedassmallerandmorefrequentshipmentsimpacttransportationmodeselectionandfreightconsolidationopportunities.JIT对物流规划问题的影响现代物流战略Thedesignofasupplyc45现代物流战略FreightConsolidation货物拼箱Individualshipmentscanbecombinedtoshareatransportationassetmakingpickupordeliverystopsatdifferentfacilities.Thistypeofconsolidationiscalledmulti-stopvehiclerouting现代物流战略FreightConsolidation货物拼46现代物流战略Individualshipmentscanbebroughttoacentrallocationorpooled,creatinglargeshipmentssuitableforeconomy-of-scaletransportationmodessuchastruckloadorrailcarload.Scheduling.Sometimesshipmentschedulescanbeadjustedforwardorbackwardintimesotheycanbecombinedwithothershipments.现代物流战略Individualshipmentscan47现代物流战略IntegrationofInboundandDistributionLogisticsHistoricallythepurchasingandschedulingofsupplier-to-plantinboundshipmentshavebeentreatedindependentlyofthedistributionofgoodscomingoutoftheplant.Coordinatinginboundandoutboundshipmentscanincreasetheutilizationofresources.Thisstrategyparticularlyimpactsshipmentplanningandvehicleroutingandscheduling.现代物流战略IntegrationofInbounda48现代物流战略Fixed/MasterRoutes&Variable/DynamicRoutesFixedandmasterroutesareregularvehicleroutesequencesandschedulesdevelopedusingaveragedemandforecasts.Fixedroutesareregularruneachperiodwithoutconsideringactualcustomerdemand,whilemasterroutesareadjustedslightlybasedonactualdemand.Incontrast,variableorirregularroutesaretailoredtoactualcustomerdemandinformation.Theextremecaseofvariableroutesisdynamicroutes,whichareadjusteddynamicallyastheroutesarerun.现代物流战略Fixed/MasterRoutes&Va49现代物流战略DistributionCenterConsolidationvs.DecentralizationCustomerscanbeservedfromsmaller,regionaldistributioncentersorfromlarger,centralizeddistributioncenters.现代物流战略DistributionCenterCons50现代物流战略Notealsothatanincreasednumberofdistributioncentersallowscloserpositioningofinventorytocustomers,reducingdeliverytimetocustomers.现代物流战略Notealsothatanincrea51现代物流战略TransportationModeSelection现代物流战略TransportationModeSele52现代物流战略Transportationmodeimpactsinventorycostsinthreedifferentways:First,slowertransportationmodescreatemorein-transitorpipelineinventory.

Second,largershipmentsizesmaycreateorderquantityinventory,whicharisesifthebatchshipmentsizeismorethantheamountofcurrentdemand.

Third,slowertransportationmodesmayraisesafetystockinventoriesneededtoprotectuncertaintiesinsupplyanddemand.Aslowertransportationmodeincreasestheorderleadtime(thetimebetweenplacinganorderandactuallyreceivingtheshipment),somoresafetystockmaybeneededtoprotectagainstthelackofknowledgeaboutdemandduringtheleadtime.Thussmallershipmentsviafastermodesreducesallthreetypesofinventories,butassociatedtransportationcostsincrease.现代物流战略Transportationmodeimpa53现代物流战略SinglesourcingorsplitsourcingSinglesourcingreferstosatisfyingallproductdemandatalocationfromonesupplier-incontrast,splitsourcingreferstomultiplesupplierssatisfyingthesamedemandlocation.Themostcommonformofsinglesourcingisbetweendistributioncentersandcustomersormarkets,witheachcustomerassignedasingledistributioncenter现代物流战略Singlesourcingorsplit54现代物流战略Singlesourcingsimplifiesthelogisticssupplychainwhichcanreducemanagementandoperationalcosts.Singlesourcingalsocreateslargervolumeshipmentsalonglanes,whichmayreducetransportationcosts.However,singlesourcingrequireseachsuppliertostockallproducts.Splitsourcingallowseachproducttobeshippedviathecheapestshippingroutetoacustomer.Splitsourcingcanalsoreducecostsifthesupplypointsarecapacitated,astheleastcostallocationofsupplymayrequiresplitshipments.现代物流战略Singlesourcingsimplifi55物流建模涉及的数据与供应链节点相关的数据Zonesdefinethegeographicalterritoriesoffacilities,suchassalesregions,customerterritories,ordistributioncenterareas.Zonescanbepre-determined(suchasmarketingterritories)orcanbecreatedautomaticallybyrulesoralgorithms.物流建模涉及的数据与供应链节点相关的数据Zonesdefi56物流建模涉及的数据与运输相关的数据Shippinglanescaneitherbepre-determinedorgeneratedbyrulesoralgorithms物流建模涉及的数据与运输相关的数据Shippinglane57物流建模涉及的数据需求数据物流建模涉及的数据需求数据58物流建模涉及的数据与配送运输相关的数据Pathsandroutesareusedtorepresentthemovementofgoodsandtransportationequipmentamongfacilities.Schedulesdescribetiminginformationassociatedwiththemovements物流建模涉及的数据与配送运输相关的数据Pathsandr59物流建模涉及的数据其它与数据相关问题Somelogisticsmodelsarebasedoncurrentlogisticsinformation.Forexample,vehicledispatchingmodelsneedinformationabouttoday’sorders,vehiclesavailable,driverstatus,etc.Futurecustomerdemand,availableproductioncapacityCurrentinformationForecastsHistoricalinformation.Stillothermodelsuseactualhistoricaldatatocalibratemodelaccuracy-modeloutputscanbecomparedtowhatactuallyhappenedtoensurethemodelisavalidrepresentationofthelogisticssupplychain.SourcesofData物流建模涉及的数据其它与数据相关问题Somelogisti60物流建模涉及的数据Time-relatedData:TheModelingHorizonAkeymodelingissueisdefiningthetimespanorhorizonofalogisticsmodel.Somemodelsaresingleperiodmodels-thereisonlyonetimeperiod,sodatainthesemodelsdoesnotchangeovertime.Incontrast,somemodelsaremulti-periodmodels,withdatapotentiallychangingfromonetimeperiodtothenext.Forexample,thecustomerdemandforsoftdrinkproductsincreasesduringthesummermonths.物流建模涉及的数据Time-relatedData:Th61物流系统模型的作用物流系统模型的作用62物流模型的简化Logisticssupplychainscanbeverylargesystemscomposedofhundredsoffacilitiesmovingtensofthousandsofproductsormore.Theonlypracticalwaytoanalyzeandimprovealogisticssystemistosimplifythelogisticsdecisionsintosmallerinterrelatedandmanageablecomponents.Twomodelsimplificationtechniquesareaggregationandpartitioning.Aggregationiscollectingor“rollingup”relateddatauptoasimplerormoreapproximaterepresentation.（数据聚合）Groupingindividualproductsorstock-keepingunits(SKUs)intoproductfamilies,representinggroupsofsimilarproductitems.Addinguptheindividualproductdemandforcustomerstogetthetotaldemandbycustomerzone.Addingupthemanufacturingcapabilitiesofindividualproductionlinesandassemblystationsintoatotalproductioncapacityforamanufacturingplant.物流模型的简化Logisticssupplychains63物流模型的简化Anotherwaytosimplifyalogisticssystemistodecoupleorpartitionthesupplychainintomoremanageablecomponents.（模型分解）Forexample,wecoulddividethedistributionsystemintoregions,anddevelopvehicleroutingmodelsseparatelywithineachregion.Ofcourse,akeypartofsupplychainmodelingistreatingthelogisticssystemasanintegratedprocess,socaremustbetakentoprovideenough“linkage”betweenthecomponentstocapturetherelevantdecisionsandissues.物流模型的简化Anotherwaytosimplify64物流模型的精确性Intheideallogisticsmodel:Alldataisavailableandcorrect.Thereisnoerrorinforecastsoffuturedata(includingcustomerdemand,availabilityofsupply,availabilityofresources,etc.).Themodelexactlycapturesalloftherelevantissuesinthelogisticssupplychain.Unfortunately,inmostsituationssomedataismissingorincorrect,theforecastsoffuturedataarewrong,andsomesupplychaincharacteristicsaretoofuzzytocapturepreciselyinamodel.Thusmostlogisticsmodelsareatbestapproximaterepresentationsoftheactuallogisticssystem.物流模型的精确性Intheideallogistics65物流模型的精确性ThisistheheartoftheEvaluateAlternativesstep.Thismodelingstep“playsout”agivenlogisticssystemconfiguration,somoredetaileddatacanbeused.TheresultisthatbaselinestatisticscanbecalculatedandusedtogaugetheprecisionofmoresimplifiedmodelsHowdoweknowifanapproximateandsimplifiedmodelisanaccuraterepresentationofthelogisticssupplychain?Simpler,higherlevelmodelsareoftenattractivewhengeneratingandrationalizingalternatives–moreprecisemodelsarepossibleduringevaluationandbenchmarkingsteps.物流模型的精确性Thisistheheartoft66物流模型的精确性Forexample,inaggregatemodelsitiscommontouseaverageorapproximatevaluesforcostsanddemandquantities.Giventhemovementofactualshipments,wecanevaluatethetrueshippingcostsandcomparewiththeapproximatecosts.Wecanthenmodifyandimprovehowweestimatetheapproximatecostsanddemandsbasedonwhatactuallyhappened.Theevaluationstepmeasurestheaccuracyofasimplifiedmodel..Simulationisageneraltermforaclassoftoolsandmodelsthatplayoutagivenlogisticssystem.Whilethesetoolsaredescriptiveonly(anddonotprescribesmartalternatives),simulationtoolscanhandlealargeamountofdetail,andcaneffectivelyrepresenttheprobabilisticelementsofalogisticssystem.Thusthesetoolsareeffectiveforevaluatingtheactualbehaviorofalogisticssystemandcalibratingtheaccuracyofmoreapproximatemodels.物流模型的精确性Forexample,inaggreg67物流建模中的成本Someofthekeycostcomponentsinalogisticssupplychain物流建模中的成本Someofthekeycostc68物流优化模型的构成Amathematicaloptimizationmodelconsistsofthefollowingthreecomponents:

Objective.maximizingprofitability,minimizinglandedcosts,maximizingon-timeshipments,orminimizingthenumberoftrucksneeded.

DecisionVariables.Wheretolocatefacilities,howtoroutefreight,andwhentosendshipments.

Constraints.Storagespaceinawarehouse,availablemanufacturingcapacityataplant,thenumberoftrucksavailable,andtheshipmentdeliverytimerequiredbyacustomer.物流优化模型的构成Amathematicaloptimi69物流优化模型的求解Somemathematicaloptimizationmodelsare“easy”inthesensethattherearealgorithmsavailablethatcanconsistentlyfindtheoptimalsolutioninapredictableamountoftime.Themostusefulmodelsinthisclassarelinearprogramming(LP)modelsSomemathematicaloptimizationmodelsare“hard”inthesensethattherearealgorithmsavailablethatcanconsistentlyfindtheoptimalsolutioninareasonableamountoftime,iftheproblemsizeissufficientlysmall.Thustheseare“limitedsizesolvable”models.Forthesemodelswecanoptimizesmallproblemsbuteithercannotoptimizelargeproblemsorcannotsolvethemwithconsistency.Manyofthemostimportantlogisticsmodelsfallintothe“hard”class.Thisincludesmostmodelsofvehicleroutingandscheduling,facilitylocationandsizing,shipmentroutingandscheduling,freightconsolidation,andtransportationmodeselection.Theseproblemscanberepresentedasmixed-integerprogrammingmodels.物流优化模型的求解Somemathematicalopt70可视化物流建模Visuallogisticsmodelingallowslogisticsanalyststospecifydecisionalternativesviaacombinationofmathematicaloptimizationandgraphicaluserinterfaces可视化物流建模Visuallogisticsmodeli71可视化物流建模可视化物流建模72物流建模的十大原则1.Objectives-mustbequantifiedandmeasurable2.Models-mustfaithfullyrepresentrequiredlogisticsprocesses3.Variability-mustbeexplicitlyconsideredIgnoringvariabilityisgenerallyareceiptforfailure.4.Data-mustbeaccurate,timely,andcomprehensive5.Integration-mustsupportfullyautomateddatatransferManuallyenteringanythingotherthanveryminoramountsofdataisbothtootimeconsumingandtooerrorpronetosupportoptimization.6.Delivery-mustprovideresultsinaformthatfacilitatesexecution,managementandcontrol物流建模的十大原则1.Objectives-must73物流建模的十大原则7.Algorithms-mustintelligentlyexploitindividualproblemstructure8.People-musthavethedomainandtechnologyexpertiserequiredtosupportthemodels,data,andoptimizationengines9.Process-mustsupportoptimizationandhavetheabilitytocontinuouslyimprove10.ROI-mustbeprovableconsideringthetotalcostoftechnology,peopleandoperations物流建模的十大原则7.Algorithms-must74第三章物流系统建模

税文兵交通工程学院物流系2013.11第三章物流系统建模税文兵Contents案例1建模的一般理论23物流系统模型Contents案例1建模的一般理论23物流系统模型76案例SheridanTechnologies,Inc.isanindustrialproductscompanyoperatingthreeplantsintheUnitedStates,plantsaretriangles,distributioncentersarecircles,andcustomergroupsaresquares.TheplantsshipfinishedproductsinTruckload(TL)quantitiestofiveDCs,ThecompanyshipsviaLess-Than-Truckload(LTL)commoncarriersoutoftheDCs,typicallyweeklyforeachcustomer.案例SheridanTechnologies,Inc.77Definitionandmainactivitiesof案例

Linksdepictthecurrentassignmentofcustomerstodistributioncenters.Thecurrentsourcingassignmentshavedevelopedhistoricallyoverseveralyears,andhavebeeninfluencedbyvariousfactorsincludingworkloadbalance,companygrowth,politics,andhistoricalpartnerships.Definitionandmainactivities78案例ThenewVicePresidentofLogisticsatSheridanTechnologieshasinitiatedastudyofthecompany’slogisticssupplychainoperations,andformedaprojectteamtoanalyzethefollowing：

顾客是否从正确的DCs获得产品?

公司是否应该考虑改变现有的DCs和顾客分配策略？应该怎样改变？Underthecompany’scurrentsinglesourcingdistributionstrategy,whatistheoptimalnumberandlocationofDCsthatminimizeslogisticscosts?Beforegeneratingandanalyzinganychangestothecurrentsystem,theprojectteamfirstwantstocreateasimplifiedmodelrepresentationandensurethemodelaccuratelyrepresentstheactuallogisticssystem.Asimplifiedmodelisdesirabletobetterunderstandthesignificantelementsandcostsofthesupplychainandtoallowalternativestoberapidlygeneratedandeasilyinterpreted.案例ThenewVicePresidentofLo79案例Oneyear’shistoricalshippinginformationwillbeanalyzedtocaptureanymonthlyorquarterlyseasonalvariationsincustomerorderingpatterns.Thecompany’smainframecomputerholdsover100,000freightbillspaidtotruckingcompanieslastyear,sotheteamdecidestosimplifytheanalysisbycalculatingtheaverageorderquantityandorderfrequencybyeachregion.第一步：Aggregatehistoricalshipmentstoestimatefuturedemand第二步：运输成本的计算和分配对于从DCs到顾客的LTLcost，使用LTLfreightratingtables.（单位数量的物品的运输费率）对于从工厂到DCs的TLcosts，使用theaverageorderquantitybyproductfamily分配每一个顾客在TL成本中所占的比例。.Usingaverageorderquantities,theestimatedannualLTLandTLcostsareabout10.5milliondollarsandabout2.1milliondollars,respectively.案例Oneyear’shistoricalshippi80案例Theratecontoursfor1000-2000poundshipmentsoriginatingfromthecompany’sRichardson,TexasDC.LTL费率一般会随着距离的增加而增大，但也有例外。Forexample,truckingratesaredisproportionatelymoreexpensiveshippingtoFlorida,becauseFloridaisaconsumingstateandtrucksmustoftenleavethestateempty.案例Theratecontoursfor1000-281案例第三步：建立模型获得新的顾客与DCs的分配方案模型的目标：totaltransportationcosts最小ThebestassignmentforeachmarketissimplytheDCdeliveringtheaveragemarketshipmentatminimaltotaltransportationcost.决策内容：

DCs与顾客最优分配关系模型的求解结果：ThetotalannualLTLandTLcostsforthissolutionareroughly10millionand2.1milliondollarsrespectively,asavingsofroughly

500thousanddollarsannually.TheteamnotestheinfluenceoftheLTLratestructureandinboundTLcostsonmarketassignments-obviouslytheDCnearestamarketisnotalwaysthebest.案例第三步：建立模型获得新的顾客与DCs的分配方案模型的目标82案例Optimalsinglesourcingassignmentusingthecurrentsetofdistributioncenters.案例Optimalsinglesourcingassi83案例第四步：研究合并现有配送中心的效果AsthereareonlyfiveDCsitiseasytoenumeratetherespectivesolutionswitheachDCclosed.Totalannualcosts(inmillions)witheachDCclosed,respectively.ClosingColumbusincreasestransportationcostsbytheleastamount.Ifthecosttooperatethisfacilityisgreaterthan$400,000annually,thenclosingthisDCreducestotalcosts.案例第四步：研究合并现有配送中心的效果Astherear84案例OptimalcustomerallocationwiththeColumbusDCclosed.AtlantaandAllentownpickupmostofthereassignedshippingvolume.案例Optimalcustomerallocation85案例第五步：研究重新构建配送中心的效果Byvisualinspectionofcustomergeographicalproximityandaverageordervolumes,theteamselects25DClocationstobeanalyzedascandidatesites.EachDCisestimatedtocost$200,000annuallytooperate,independentoftheactualshipmentvolumehandledbytheDC.Lastly,theteamdevelopsamixed-integermathematicaloptimizationformulationwithopen/closeintegervariablesrepresentingopening/closingcandidateDCs.Thetotaltransportationcostofthissolutionisroughly$10millionannually,asavingsofover$2millionannuallycomparedtoeither