物流系统中心选址模型简介.ppt

FacilitylocationmodelsfordistributionsystemdesignThedesignofthedistributionsystemisastrategicissueforalmosteverycompany.Theproblemoflocatingfacilitiesandallocatingcustomerscoversthecoretopicsofdistributionsystemdesign.
Industrialfirmsmustlocatefabrication(制造厂)andassemblyplants(组装厂)aswellaswarehouses(仓库).Storeshavetobelocatedbyretailoutlets(零售网点).Theabilitytomanufactureandmarketitsproductsisdependentinpartonthelocationofthefacilities.

Similarly,governmentagencieshavetodecideaboutthelocationofoffices,schools,hospitals,firestations,etc.

Ineverycase,thequalityoftheservicesdependsonthelocationofthefacilitiesinrelationtootherfacilities.TypesofmodelsFacilitylocationmodelscanbebroadlyclassifiedasfollows:Modelswithoutcapacityconstraintsdonotrestrict(限制)demandallocation.Ifcapacityconstraintsforthepotentialsiteshavetobeobeyeddemandhastobeallocatedcarefully.
Inthelattercasewehavetoexaminewhethersingle-sourcing(单来源)ormultiple-sourcing(多来源)isessential.
Single-stagemodels(单阶段模型)focusondistributionsystemscoveringonlyonestageexplicitly.
Inmulti-stagemodels(多阶段模型)theflowofgoodscomprisingseveralhierarchical(层次)stageshastobeexamined.
Single-productmodels(单产品模型)arecharacterizedbythefactthatdemand,costandcapacityforseveralproductscanbeaggregatedtoasinglehomogeneousproduct.
Ifproductsareinhomogeneoustheireffectonthedesignofthedistributionsystemhastobeanalyzed,viz.multi-productmodels(多产品模型)havetobestudied.

Locationmodelsbaseontheassumptionthatdemandisinelastic(无弹性的),thatis,demandisindependentofspatialdecisions.
Ifdemandiselastic(弹性的)therelationshipbetween,e.g.,distanceanddemandhastobetakenintoaccountexplicitly.Inthelattercasecostminimization(成本最小)hastobereplacedthrough,forexample,revenuemaximization(收益最大).
Staticmodels(静态模型)trytooptimizesystemperformance(性能)foronerepresentative(代表)period.
Bycontrastdynamicmodels(动态模型)reflectdata(cost,demand,capacities,etc.)varyingovertimewithinagivenplanninghorizon.

Inpracticemodel(实践模型)inputisusuallynotknownwithcertainty.Dataarebasedonforecastsand,hen