系统工程作业Word文档下载推荐.docx
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系统工程作业Word文档下载推荐.docx
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1Introductiontothebasictheory
1.1Dynamicprogramming
Seekingtheshortestpathisanimportantbranchofoperationsresearchandhasbeenwidelyusedinpractice.Sucheffectivewayshasbeenofferedinoperationsresearchabouthowtofindtheshortestpathinthenetworkasdynamicprogramming,networkdiagramsandsoon.Inthepaper,wemainlyuseAHPandthedynamicprogrammingmethodfortheshortestpathinthesupplychain.Tobeginwith,thebasicprinciplesofdynamicprogrammingareintroducedasfollows:
Thetwobasicequationsrepresenttherecurrencerelationinthedynamicprogramming,inwhichkisdescribedasstagevariable,
asthereachablestateset,
asthedecisionvariablesinkstage,
asthesetofpossibledecisions,
asthedistancefrom
to
astheshortestdistancefrom
inkstagetotheend.Optcanbetakenasminormaxaccordingtothepracticalmeaningofdifferentproblemsandtheindexfunctionalsobetakenasdistance,time,profits,costs,productionorresourceconsumptionindifferentcases.
1.2Analytichierarchyprocess
ThefamousoperationsresearchexpertinAmericanT.L.SaatyputforwardthedecisionmethodAHPinthe1970sbasedonMultipletargetsandmultiplecriteria,whichdividedacomplexproblemintoseveralcomponentsorfactorswhichcomposeahierarchicalstructureaccordingtothegovernrelationsamongthem.Then,multiplecomparisonresultsindicatetherelativeimportanceofcomponents.Afterthat,referringtorelatedexperts’determination,therelativeimportanceorderofvarioussubstituteschemeswouldbeobtained.Inthewholeprocess,thismethodreflectsthethinkingcharacteristics“analysis-determination–synthesis”.AHPmethodcanberoughlydividedintothefollowingfivesteps.
1.2.1Tomakethefactorsofthissystemandtheirrelationshipclearandcreateahierarchicalstructureofthesystem
Toclassifythebasicfactorsastheircharacteristicsinthissystemandanalyzetherelationshipofthesefactors,thenconstructthesystemhierarchicalstructure,asshowninthefigure1.
Fig.1Thesystemhierarchicalstructure
1.2.2Toconstructthemultiplecomparisonmatrix
Aftercomparingwiththetwofactorsonthesamelevelabouttheimportancetooneuppercriterion,establishthejudgmentmatrixforeachlevel.Intheadjacentlevels,theupperistarget,andthelowerisfactors.Meanwhile,thejudgmentresultcanbequantifiedby“1-9”scalemethodwhichhasbeenshownintable1.
1.2.3Tocalculaterelativeimportance
TocalculatetherelativeimportancevectorWi,andtheunifiedrelativeimportancevectorWi0,totheuppercriterionforeachfactor,inthisstep,thearithmeticmethodisalwaysadoptedtocalculateWiandWi0.Theresultisshownasfollowingequalities.
Tab.1Meaningsofscale
Ratioscale
meanings
1
Comparingthetwoelements,theyhavethesameimportance
3
Comparingthetwoelements,theformeroneisweaklymoreimportantthantheother
5
Comparingthetwoelements,theformeroneisintensivelymoreimportantthantheother
7
Comparingthetwoelements,theformeroneisobviouslymoreimportantthantheother
9
Comparingthetwoelements,theformeroneisextremelymoreimportantthantheother
2,4,6,8
Indicatetheabovementionedadjacentjudgments’middlevalue
1.2.4Todoconsistencytest
Inordertotesttheconsistencyofmatrix,wedefinetheConsistencyIndexofthematrixasC.I.:
Whentheyareexactlyconsistent,thevalueofC.I.is0.WiththeC.I.greater,theconsistencyofthematrixisgoingtobeworse.Inordertoovercometheshortcoming,weintroduceAverageRandomConsistencyIndex(R.I.)toreviseC.I..Forthematrixof1to9,theR.I.isshownintable2:
Tab.2TheAverageRandomConsistencyIndexR.I.
order
1
2
3
4
5
6
7
8
R.I.
0
0.58
0.90
1.12
1.24
1.32
1.41
1.46
TheC.R.iscalledtherandomconsistencyratioofthematrix;
andwhenC.R.<
0.10,ornearto0.1,thematrixhasbeenconsideredasthesatisfiedconsistency;
otherwisereadjustmentneedstobedone.
1.2.5Tocalculatesyntheticweightandsortthesubstituteschemes
Tocalculatetheoverallimportanceofeachschemeandsortthefinalresult.
1.3Networkoptimization
Networkoptimizationistofindtheshortestpathofthenetworkintheinitialprogrammingandthenaccordingtotheprincipleofoptimalitytotakefullaccountoffactorssuchastime,resources,costssothattheselectedoptimalpathcanachievebestpossibleoptimizationssynthetically.
(1)Time-costoptimization,awaytoseekthelowesttotalcostsfortheshortesttimeconsideringtherelationshipbetweenthelogisticsprocessandfees,whichcanbeusedtomakelogisticsplansinthesupplychain.
(2)Time-resourceoptimization,awaytoseekminimumresourcesandminimumtimeconsideringtherelationshipbetweenthetimeandtheresourcesused,whichcanbeusedtomakeprocurementplansinthesupplychain.
(3)Syntheticoptimizationoftime,resources,costs,whichgivesfullconsiderationtotheoverallbalanceoftime,resourcesandcostinordertoachievetheultimategoalusingtheleastresourcesandtheminimumfeeintheshortestpossibletime.Thiswayhasbeenwidelyusedinsupplychainmanagement.
1.4Thesimilaritiesanddifferencesofthetheoryofgeneralnetworkoptimizationandsupplychainnetworkoptimization
Generalnetworkoptimizationreferstooptimizetheshortestpathinthenetworkwithcertainmethods,makingtheknownshortestpathtoachieveoptimal.
Supplychainnetworkoptimizationincludestwoideas:
(1)firstinlinewiththeprincipleofgeneralnetworkoptimization;
(2)usingtheshortestpathinindustrysupplynetworkasabenchmarktooptimizeothersupplychains.
2Overviewofthesupplychainnetwork
2.1Industrysupplynetworkandenterprisesupplychain
Industrysupplynetworkisalargeandcomplexnetworksystem,acombinationofalltherelevantenterprisesproducingthesameorsimilarproductsoralternativeproductsandusers.Inthesystem,therearemanydifferentsinglesupplychains,crossingeachothertoprovideservicesforthefinalconsumerssoastoachievetheultimateconsumerutilitymaximization,andthereexistsacompetitiverelationshipamongthesesinglesupplychains.
Enterprisesupplychainmeanssinglesupplychaingenerallyreferredto,akindofchainstructureornetworkstructurecomposedofrawmaterialsuppliers,manufacturers,distributors,retailersandcustomersbyconnectingwiththeupstreamanddownstreammembers.Soenterprisesupplychainisapartoftheindustrysupplychain.
2.2Optimalindustrysupplychain
Theso-calledindustryoptimalsupplychainistoseekthesupplychainwhichisoptimalintheindustrysupplychainnetworkorthebestinpracticeunderoneorseveralstandardsasoptimizationbenchmarkofothersupplychains.
2.3Enterprisesupplychainoptimization
Enterprisesupplychainoptimizationistolocatethedifferencesofenterprisesupplychainfromthebenchmark,theindustryoptimalsupplychain,thentoreducethembyoptimizingenterprisesupplychain,eventuallyreachingthestandardofthereferredsupplychaintoimproveeffectivenessandmarketcompetitivenessofthechain.Intheoptimizationprocess,themethodofpartiallycoordinated,overallintegratedandthereconstructionmethodcanbothbeusedtoarriveatthedestination.
3ApplicationofdynamicprogrammingandAHPinthesupplychainselectionandreconstruction
3.1Basicassumptions
Thesupplychainisalargeandcomplexsystem.inordertosimplifythestudy,weneedtodosomeassumptionsaboutthesupplychaintosimplifythesystemsothatthereadersareabletounderstandthenetworkoptimizationmethodmoreclearly.Thebasicassumptionsareasfollows:
(1)Thereareonlyaninitialrawmaterialsupplierandafinalconsumerinthenetwork;
(2)Supplynetworkconsistsofthreetierofsuppliers,atierofmanufacturersandtwotierofdistributors;
(3)Themanufactureristhecoreenterpriseofthesupplychain;
(4)Theindustrysupplynetworkprovidesonlyoneproduct;
(5)Theinternalcostsarealreadytheoptimalineachcompany,whichbecomesjustanodewithoutaccountingforthecosts,resources,timeandsoon.Inaddition,thecostsoffirstrawmaterialsarenottakenintoconsideration.
Fig.2Industrysupplynetwork
3.2Industrysupplynetwork
Aftertheabovebasicassumptions,supplynetworkofcertainindustryisdescribedasshowninfigure2andthisnetworkcanbeadirectedone(arrowsindicatethedirectionoflogistics).Nodesinthegraphstandforeachbusiness,Efortheultimateconsumer,thearrowsfortransactioncostsortimebetweenthetwoconnectedpoints,thenumberinarrowlinesforthevalueofexpensesortime,forinstance
isthetransactioncostsbetweenAand
.Thepointsnotconnectedtoeachotherinthenetworksuchas
meansthatonepointdoesnotmeettherequirementsoftheotherandhavetostrivetobecomeoneoftheenterprises,orthatthestrengthoftheenterpriseissostrongthatitisno
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