具有環(huán)保意識的供應(yīng)鏈網(wǎng)絡(luò)長期設(shè)計規(guī)劃

精選優(yōu)質(zhì)文檔-----傾情為你奉上精選優(yōu)質(zhì)文檔-----傾情為你奉上專心---專注---專業(yè)專心---專注---專業(yè)精選優(yōu)質(zhì)文檔-----傾情為你奉上專心---專注---專業(yè)Environmentallyconsciouslong-rangeplanninganddesignofsupplychainnetworks具有環(huán)保意識的供應(yīng)鏈網(wǎng)絡(luò)長期設(shè)計規(guī)劃AbstractInthispaper,amathematicalprogramming-basedmethodologyispresentedfortheexplicitinclusionoflifecycleassessment(LCA)criteriaaspartofthestrategicinvestmentdecisionsrelatedtothedesignandplanningofsupplychainnetworks.Byconsideringthemultipleenvironmentalconcernstogetherwiththetraditionaleconomiccriteria,theplanningtaskisformulatedasamulti-objectiveoptimizationproblem.Overalong-rangeplanninghorizon,themethodologyutilizesmixedintegermodelingtechniquestoaddressstrategicdecisionsinvolvingtheselection,allocationandcapacityexpansionofprocessingtechnologiesandassignmentoftransportationlinksrequiredtosatisfythedemandsatthemarkets.Attheoperationallevel,optimalproductionprofilesandflowsofmaterialbetweenvariouscomponentswithinthesupplychainaredetermined.Assuch,theformulationpresentedherecombinestheelementsoftheclassicalplantlocationandcapacityexpansionproblemswiththeprinciplesofLCAtodevelopaquantitativedecision-supporttoolforenvironmentallyconsciousstrategicinvestmentplanning.本文提出一種數(shù)學(xué)規(guī)劃方法，明確納入生命周期評估準(zhǔn)則作為與設(shè)計規(guī)劃供應(yīng)鏈網(wǎng)絡(luò)有關(guān)的戰(zhàn)略投資決策的一部分。通過將多環(huán)境問題和傳統(tǒng)經(jīng)濟(jì)標(biāo)準(zhǔn)一起考慮，規(guī)劃任務(wù)是一個多目標(biāo)優(yōu)化問題。在長期規(guī)劃中，利用混合整數(shù)建模技術(shù)解決戰(zhàn)略決策問題，其包括選擇，分配和擴(kuò)容加工技術(shù)，及滿足市場需求的運(yùn)輸。在操作層面上，決定供應(yīng)鏈內(nèi)部各個組成部分的最優(yōu)生產(chǎn)概況和物質(zhì)流。因此，這里提出的公式結(jié)合工廠定位和LCA原則的能力擴(kuò)展問題來發(fā)展一個定量決策工具以支持具有環(huán)保意識的戰(zhàn)略投資規(guī)劃。1.IntroductionIncreasinglytherehasbeenanawarenessoftheimpactthatextendedchemicalproductionsystemshaveontheenvironment,resultinginenterprise-widemanagementstrategiessuchasproductstewardship,lifecycleassessment(LCA)andindustrialecology.However,despitetheconsensusabouttherelevanceandbenefitsofadoptingmoresustainablebusinesspracticesacrossentirechemicalproductvaluechains,thegreatestchallengestillliesinthepracticalapplicationoftheenvironmentalmanagementstrategiesinpursuitoftechnologicalinnovations.Overtheyears,theprocessengineeringcommunityhasrecognizedthischallengewiththeresultbeingavarietyofapproachesaimedattheplant-levelforenvironmentallyconsciouschemicalprocessdesign.Intheirextensivereviewofover180citationsrelatedtotheareaofenvironmentallyconsciouschemicalprocessdesign,Cano-RuizandMcRae[1]analyzevariousmethodologiesthatconsideravoidingenvironmentaldamageaspartoftheprocessdesignobjectives.Undoubtedly,themostimportantconclusionfromtheirreviewisthatbyadoptingastrategythatconsiderstheenvironmentasadesignobjectiveandnotmerelyasaconstraintonoperationscanleadtothediscoveryofnovelprocessingalternativesthatachievebothimprovedeconomicandenvironmentalperformance.擴(kuò)大化學(xué)生產(chǎn)系統(tǒng)對環(huán)境產(chǎn)生影響的意識已經(jīng)被越來越多的人注意到，導(dǎo)致了企業(yè)范圍的管理策略如產(chǎn)品管理，生命周期評估（LCA）和工業(yè)生態(tài)學(xué)。然而，盡管在整個化學(xué)產(chǎn)品價值鏈中實(shí)施更多的可持續(xù)商業(yè)慣例的相關(guān)性和效益型已經(jīng)達(dá)成了共識，最大的挑戰(zhàn)始終是在追求技術(shù)革新時，環(huán)境管理策略的實(shí)際應(yīng)用。多年來，過程工程社區(qū)已經(jīng)認(rèn)識到這項(xiàng)挑戰(zhàn)，這種挑戰(zhàn)帶有成為許多方法的結(jié)果，這種方法目的在與環(huán)保意識化工過程設(shè)計的工廠水平。在他們的對180多個有關(guān)環(huán)保意識的化學(xué)工藝設(shè)計領(lǐng)域引文的廣泛回顧后，Cano-RuizandMcRae[1]分析了各種研究方法，考慮將避免環(huán)境破壞作為工藝設(shè)計目標(biāo)的一部分。毫無疑問，最重要的結(jié)論是通過采取將環(huán)境作為設(shè)計目標(biāo)之一而不僅僅是操作限制的策略可以導(dǎo)致新加工方案的發(fā)現(xiàn)，這種方案可以同時提高經(jīng)濟(jì)業(yè)績和減小環(huán)境影響。However,formulatingtheprocessdesignproblemsuchthatenvironmentalconcernsaretreatedasdecision-makingobjectivesinsteadofconstraintsrequires(a)quantifyingsuitableenvironmentalperformancemeasures,and(b)balancingtheenvironmentalcriteriaagainstthetraditionalcostincentives.Especially,theselectionofappropriateperformanceindicatorshasproventoposeasignificantobstacleindevelopingadesignstrategydrivenbyanenvironmentalobjective.Effortshave,therefore,focussedondevelopingindicesthatcanbeusedwithinaquantitativeprocessdecisionmakingframework[2,3].Inthisrespect,LCA[4]hasalsoproventofacilitatetheenvironmentalimpactassessmentofachemicalprocessdesign[5].然而，規(guī)劃工藝設(shè)計問題如環(huán)境問題時，將其作為決策目標(biāo)而不是作為適當(dāng)?shù)沫h(huán)境績效指標(biāo)量化的限制規(guī)定，并且在環(huán)境標(biāo)準(zhǔn)和傳統(tǒng)的成本激勵中尋求平衡。特別是，合適的績效指標(biāo)的選擇證明在環(huán)境目標(biāo)驅(qū)動下制定設(shè)計策略有重大障礙。因此，重點(diǎn)提出定量過程的決策框架使用的指標(biāo)。在這方面，LCA使化學(xué)工藝設(shè)計的環(huán)境影響評估變得方便。Onceasuitableimpactassessmenttechniquehasbeenapplied,theresultingenvironmentalperformancemeasurescanbetraded-offagainsttheeconomicobjectiveseaswellasagainsteachother-togenerateandevaluatealternatives.Anumberofdesignmethodologiesaimedattheplant-levelhaveincorporatedmultiplecriteriadecision-making(MCDM)techniquesaspartoftheprocessdesigntask[3,6-11].Multi-objectiveoptimization,beingoneparticularMCDMapproach,triestoidentifythesetofnon-inferioralternativesolutionsbeforetheyareexplicitlyevaluated[12].Assuch,thefeasiblealternativesarenotexplicitlyknowninadvanceanditisacknowledgedthataninfinitenumberofsolutionspotentiallyexist.Inasimilarspirit,theMethodologyforEnvironmentalImpactMinimizationwasdevelopedwiththeaimofcapturingdiverseenvironmentalconcernsasobjectiveswithinaformalquantitativeprocessdesignandoptimizationframework[13,14].一旦一個合適的影響評估技術(shù)被應(yīng)用，由此產(chǎn)生的環(huán)境性能措施可以在經(jīng)濟(jì)目標(biāo)之間權(quán)衡，也可以在產(chǎn)生和評估方案中權(quán)衡。許多設(shè)計方法目的是工廠納入多準(zhǔn)則決策目標(biāo)（MCDM）技術(shù)作為工藝設(shè)計任務(wù)的一部分[3,6-11]。作為一個特定的MCDM方法的多目標(biāo)優(yōu)化，試圖在被明確的評估之前找出非劣勢解決方案的解集[12]。因此，不會明確地事先知道可行的替代方案，而且一個無窮的解決方案是可能存在的。類似的，設(shè)計環(huán)境影響最小化的方法，其目的是在定量工藝設(shè)計和優(yōu)化框架中將不同的環(huán)境問題作為目標(biāo)[13,14]。Whilethesepreviousapplicationshavesuccessfullyincludedenvironmentalconsiderationswithinaprocessdesigncontext,limitedworktodatehasbeenconductedontheextensionofthesametrade-offanalysismethodologytoassistthestrategicplanninganddesignofextendedsupplychainnetworks.Theopportunitynaturallyexiststoexpandtheprocesssystemsboundarytoallowthestructureofthesupplychainnetworktobeadesigndecisionwithintheoverallprocessoptimizationframework.雖然這些以前的應(yīng)用在工藝設(shè)計中成功包含環(huán)境因素，迄今為止有限的工作是進(jìn)行權(quán)衡分析方法的擴(kuò)展，以協(xié)助戰(zhàn)略規(guī)劃和供應(yīng)鏈網(wǎng)絡(luò)的設(shè)計。機(jī)會自然存在以擴(kuò)大流程系統(tǒng)的邊界，使供應(yīng)鏈網(wǎng)絡(luò)結(jié)構(gòu)在整個流程優(yōu)化框架中成為一個設(shè)計決策。Incontrasttotheprocessdesigntask,supplychainmanagementisconcernedwithactivitiesrelatedtoabroaderrangeofbusinesspractices,suchasprocurement,processing,marketing,distributionandretail.Itadoptsafundamentalsystems-basedapproachwherebyextendedenterprisesareseenasanintegratednetworkofcooperatingcompaniesinsteadofisolatedhierarchialones.Decisionsgenerallycorrespondtofouractivities-scheduling,operational,tacticalandstrategic[15].Traditionally,thegoalofresearchintosupplychainactivitieshasbeentoachievegreatercorporatecompetitivenessthroughenterpriseefficiencybydeliveringanincreasingnumberofproducts,ingreaterquantities,atthetimeofproductdemand.Inordertoachievethesegoals,quantitativeanalysis,modelling,optimizationanddesignofthesupplychainshavebeenrecognizedasinvaluabletoolsforsupportingthedecision-makingprocess[16].Despitethesignificantadvancesinthedevelopmentofsupplychaindecision-supporttools,limitedattentionhasbeengiventoincorporatingquantitativeenvironmentalperformancemodelling[17].Thisissurprising,especiallyifoneconsidersthemanysimilaritiesbetweenemergingenvironmentalmanagementstrategiesandtraditionalsupplychainresearchactivities[18].Forexample,totalqualitymanagement,aimingatreducingoverallcostacrosstheenterprise,requiresjustaslifecycleassessmentandproductstewardshipknowledgeoftheentireintegratedvaluechain.Furthermore,manypressuresresultingfromsupplychaindynamicsbetweenbuyersandsupplierscanofteninitiateenvironmentalchange[19].與流程設(shè)計任務(wù)相比，供應(yīng)鏈管理與更廣泛的商業(yè)行為有關(guān)，比如采購、加工、市場配送和零售。它采用了基本系統(tǒng)基礎(chǔ)方法，將企業(yè)擴(kuò)大看做合作公司的綜合網(wǎng)絡(luò)而不是孤立的。決策一般與計劃、運(yùn)營、戰(zhàn)術(shù)和戰(zhàn)略四個活動相對應(yīng)[15]。傳統(tǒng)上，供應(yīng)鏈的研究目標(biāo)是，通過在有需求時提供越來越多的產(chǎn)品使企業(yè)具有更大的競爭力。為了達(dá)到這個目標(biāo)，供應(yīng)鏈的定量分析、建模、優(yōu)化和設(shè)計已經(jīng)被確認(rèn)為寶貴的工具，以支持決策過程[16]。盡管供應(yīng)鏈決策支持工具的開發(fā)有了很大的進(jìn)展，納入定量環(huán)境績效模型的的研究很有限[17]。這是令人驚訝的，尤其如果考慮到新興的環(huán)境管理策略和傳統(tǒng)的供應(yīng)鏈研究活動間的許多共同點(diǎn)[18]。例如，以減少整個企業(yè)的成本為目標(biāo)的全面質(zhì)量管理，需要整個價值鏈集成的生命周期評估和產(chǎn)品管理知識。此外，由買方和供應(yīng)商在之間的動態(tài)供應(yīng)鏈導(dǎo)致的壓力常來自環(huán)境的變化[19]。AnindustrialapplicationofenvironmentallyconscioussupplychainmanagementcanbefoundinUnilever,whereanecometricapproachtoassessandquantifytheoveralleffectthatabusinesshasontheenvironmenthasbeendeveloped[20].Applicationofthisecometricapproachhasbeenusedtoillustratetherelationshipbetweenaddedvalueandenvironmentalimpactalongthesupplychainofmobiletelephones[21].Recently,theindustrialecologyconceptwasextendedbymodellingmacrolevelwasteexchangenetworksusingGeographicInformationSystems(GIS)data[22].OperationsResearch(OR)hasalsosuccessfullyaddressedavarietyofenvironmentalproblemsoutsidethetraditionalsupplychainmanagementarea,suchaswaterresourcemanagement,solidwastedisposaloperationsandairqualitymanagement[23].一種具環(huán)保意識的供應(yīng)鏈管理的工業(yè)應(yīng)用可以在聯(lián)合利華中找到，一種評估和量化企業(yè)在環(huán)境方面整體效果的生態(tài)測量方法已經(jīng)開發(fā)[20]。這種生態(tài)測量方法的應(yīng)用已經(jīng)被用于證明移動電話供應(yīng)鏈的附加價值和環(huán)境影響之間的關(guān)系[21]。近來，工業(yè)生態(tài)學(xué)的概念已經(jīng)被宏觀的廢物交換網(wǎng)絡(luò)建模擴(kuò)展，其利用了地理信息系統(tǒng)數(shù)據(jù)（GIS）。運(yùn)籌學(xué)（OR）已經(jīng)成功解決了傳統(tǒng)供應(yīng)鏈管理區(qū)域以外許多的環(huán)境問題，比如水資源管理、固體廢物處理和空氣質(zhì)量管理[23]Multi-objectiveoptimizationmodelswhereenvironmentalconcernsareincludedhavealsobeenproposedtodeterminetheoptimalstructureofthepetrochemicalindustry[24].Trade-offanalysistechniqueswereusedtoestablishtherelationshipbetweentoxicityandcostofmanufacturingchemicalsinthestrategicdesignoftheoptimumindustrialstructure.Similarly,themethodofsumofweightedobjectivefunctionswasusedtogeneratetheefficientsetofpossibleconfigurationsfor297manufacturingprocesses[25].Theinherentassumptioninboththeseexamplesisthatthetoxicityofthemainproductmanufacturedrepresentsthepotentialenvironmentaldamageofthemanufacturingprocess.Amorerigorousanalysiswouldalsoincludetheenvironmentalimpactsresultingfromthedischargeofthebyproducts,wastesandemissionsofboththemainmanufacturingprocessaswellasitsoff-siteutilityandmaterialsuppliers.環(huán)境問題的多目標(biāo)優(yōu)化模型已經(jīng)被提出，來確定石化工業(yè)的優(yōu)化結(jié)構(gòu)[24]。在優(yōu)化工業(yè)結(jié)構(gòu)的戰(zhàn)略性設(shè)計中，權(quán)衡分析技術(shù)用來確定制造化學(xué)的的毒性和成本之間的關(guān)系。同樣的，加權(quán)目標(biāo)函數(shù)方法被用于297個制造流程的可能配置的有效集合的生成[25]。這兩個例子固有的假設(shè)是，主要產(chǎn)品的毒性代表制造流程的潛在環(huán)境破壞。一個更加嚴(yán)格的分析也將包括副產(chǎn)品排出的環(huán)境影響，主要制造流程的廢物和排放及場外工具和材料供應(yīng)商。Inthispaper,wefocusonextendingourpreviouslydevelopedMethodologyforEnvironmentalImpactMinimizationbypresentingagenericmathematicalprogrammingmodelforassistingthestrategiclong-rangeplanninganddesignofchemicalsupplychainnetworks.Firstly,theproblemthatthemodelwilladdressisformallystated.Next,thefeaturesandcapabilitiesofthemodelaresummarized.Thedetailedmathematicalformulationthenfollows,highlightingtheuseofmixedintegermodellingtechniquestocapturethevariousstrategicplanningdecisions.ParticularemphasisisplacedontheuseofarecentlydevelopedimpactassessmentmethodwithinthequantitativeLCAframework.Anotherimportantfeatureofthemodelistheexplicitmodellingoftheeconomiesofscalethatdictatecapitalinvestmentdecisionsassociatedwithoptimalselecting,installingandexpandingprocessingtechnologies.Themodelformulationconcludeswiththemultiobjectiveoptimizationframeworkanditssolutionalgorithm.Finally,anillustrativeexampleispresentedinvolvingthedesignandlong-rangecapacityplanningofabulkchemicalssupplychain.本文中，我們通過提出通用的數(shù)學(xué)規(guī)劃模型來擴(kuò)展我們以前提出環(huán)境影響最小化的方法，以協(xié)助長期戰(zhàn)略決策和化學(xué)供應(yīng)鏈網(wǎng)絡(luò)設(shè)計。首先，正式聲明模型解決的問題。其次，總結(jié)模型的特點(diǎn)和功能。然后是詳細(xì)的數(shù)學(xué)公式，強(qiáng)調(diào)使用混合整數(shù)模型技術(shù)獲得各種戰(zhàn)略決策。特別強(qiáng)調(diào)的是在定量LCA框架中使用最近成熟的影響評估方法。模型另一個重要的特點(diǎn)是規(guī)模經(jīng)濟(jì)的詳細(xì)建模，它規(guī)定了與最優(yōu)化選擇、安裝和擴(kuò)展加工技術(shù)有關(guān)的資金投資決策。該模型的結(jié)論是多目標(biāo)優(yōu)化框架和其算法。最后，給出一個涉及大宗化學(xué)品供應(yīng)鏈的設(shè)計和長遠(yuǎn)規(guī)劃能力的案例。2.ProblemformulationTheenvironmentallyconsciousprocessselectionproblemforthelong-rangeplanninganddesignofchemicalsupplychainnetworkscanbestatedasfollows.具有環(huán)保意識的化學(xué)品供應(yīng)鏈長遠(yuǎn)設(shè)計和規(guī)劃的問題選擇，可歸納如下：Given：●asetofmarkets(distributorsorcustomers)andtheirdemandsforasetofchemicalsoveragivenfuturelong-termperiod(planninghorizon),在一個給定的未來長期期間內(nèi)的（規(guī)劃期）的化學(xué)品的市場（分銷商和顧客）及需求?！馻setofcandidateplantsusingknowntechnologiestoproducethedesiredproducts,使用已知技術(shù)制造所需產(chǎn)品的候選工廠?！馻setofpotentialgeographicalsitesforlocatingtheplants,and建廠的潛在地理區(qū)域●theavailabilitiesoftherawmaterialandutilitysuppliersovertheplanninghorizon,規(guī)劃期內(nèi)原材料和設(shè)備供應(yīng)商的有效性，thetaskisto任務(wù)是●designthesupplychainnetworkoftheintegratedproductionfacilitiesthatwouldsatisfythedemandovertheentireplanninghorizon,設(shè)計綜合生產(chǎn)設(shè)施供應(yīng)鏈網(wǎng)絡(luò)，能滿足整個規(guī)劃期的需求suchthatboththe而使(1)netpresentvalueofthecapitalinvestmentevaluatedattheendoftheplanninghorizon,ismaximizedandthe在規(guī)劃期末評估資金投資的凈現(xiàn)值，使其最大化(2)impactthattheentirenetworkhasontheenvironmentisminimized整個網(wǎng)絡(luò)的環(huán)境影響最小化。Whilethisproblemstatementcontainselementsofaclassicaldynamicplantlocationproblemforsitingproductionfacilitieswithinasupplychaincontext[26],italsoresemblesmodelsdevelopedforthechemicalprocessingindustrytoassisttechnologyselection[27-29]andlong-rangecapacityplanning[30-32].Featuresofmulti-sitesupplychainnetworkmodelswherebothoperationandstrategicdecisionsareaddressedarealsocapturedwithinthisproblemformulation[33,34].雖然問題的陳述包括供應(yīng)鏈中傳統(tǒng)的動態(tài)工廠選址問題[26]，它類似于化學(xué)加工工業(yè)模型，以協(xié)助技術(shù)選擇[27-29]和長遠(yuǎn)規(guī)劃[30-32]。解決操作和戰(zhàn)略決策問題的多站點(diǎn)供應(yīng)鏈網(wǎng)絡(luò)模型的的特點(diǎn)在問題規(guī)劃中獲得[33,34]。AsillustratedinFig.1,themodelproposedheretosolvetheaforementionedproblemisbaseduponasupplychainnetworksuperstructureconsistingofasetofNMexistingmarkets-representinganaggregationofdistributioncentresandfinalcustomers-demandingasetofNIchemicalproducts(notationforthemodelvariablesispresentedinTable1).AlsogivenisinformationregardingthelocationandavailabilityofasetofNRchemicalfeedstocksuppliers.AtthecenterofthesuperstructureisasetofNJcandidatechemicalprocessingtechnologies(plants)thatcanperformtheconversionoftherawmaterialsintofinalproducts.Asimplifyingassumptionismadethatrawmaterialsaresuppliedonlyfromsinglesources.如圖一所示，這里提出的解決上述問題的模型是基于供應(yīng)鏈網(wǎng)絡(luò)上層建筑的，其包括HM存在市場，即配送中心和最終客戶的集合；化學(xué)產(chǎn)品需求（模型的變量在表1中提供）。同時，關(guān)于選址和橡膠原材料供應(yīng)量信息也是提供的。在上層建筑的中心是新澤西州候選化學(xué)加工技術(shù)（工廠），可以完成從原材料到最終產(chǎn)品的轉(zhuǎn)換。簡單的假設(shè)原材料只有唯一的來源。

Strategicdecisionsincludedaretheselectionoftheoptimumcombinationofplantsfromthesetofcandidates,aswellastheallocationoftheseselectedplantstoasetofNSpotentialgeographicalsites.Inaddition,theoptimalnetworkoftransportationlinksbetweentheselectedsitesandexistingmarketsneedstobedesigned.AllthesedecisionsareperformedintermsofafinitenumberofNTtimeperiods(typicallyinunitsofyears)constitutingthelong-rangeplanninghorizonduringwhichprices,demandsandavailabilitiesofthechemicals,andfixedinvestmentandoperatingcostsoftheplantscanvary.Attheoperationallevel,optimalplantexpansioncapacities,productionprofilesandtheflowsofmaterialsbetweenthevariouscomponentswithinthesupplychainaredeterminedovertheentireplanninghorizon.戰(zhàn)略決策包括候選工廠中選擇最優(yōu)化組合，將所選的工廠分配到潛在的地理位置中去。此外，需要設(shè)計所選的地點(diǎn)和已存在的市場之間的交通聯(lián)系優(yōu)化網(wǎng)絡(luò)。所有的決策在期間（通常以年為單位）內(nèi)按照限定的數(shù)目完成，決策包括長期規(guī)劃期內(nèi)的價格、需求和化學(xué)品的供應(yīng)量、固定資產(chǎn)投資和可變運(yùn)營成本。在運(yùn)營層面上，優(yōu)化工廠擴(kuò)大能力，生產(chǎn)概況和供應(yīng)鏈不同組成部分間的物質(zhì)流也將在這個計劃期內(nèi)決定下來。Unlikemosttraditionalapproacheswhereonlyaneconomiccriterionisconsidered,themodeldevelopedherealsoaimsatfindingthenetworkconfigurationandcapacityplanningstrategythatminimizetheenvironmentalimpactoftheentiresupplychain.Consequently,theformulationresultsinamulti-objectivemixedintegerlinearprogramming(moMILP)problem,allowingtheinherenttrade-offsbetweentheconflictingeconomicandenvironmentalobjectivestobeexplored.不像大部分只考慮經(jīng)濟(jì)標(biāo)準(zhǔn)的傳統(tǒng)方法，這里提出的模型目的在于減小整個供應(yīng)鏈環(huán)境影響的網(wǎng)絡(luò)配置和能力規(guī)劃策略。結(jié)果，應(yīng)用多目標(biāo)混合整數(shù)線性規(guī)劃問題，探討經(jīng)濟(jì)和環(huán)境之間的內(nèi)在權(quán)衡。Asameasureoftheprofitabilityofthenetwork,theexpectednetpresentvalue(NPV)oftheinvestmentrequiredtoinstall,expandandoperatetheplantsisusedastheeconomicobjectivefunction.Incontrast,theecologicalobjectivefunctionisbasedupontheenvironmentalimpactresultingfromtheoperationoftheentirenetworkovertheentireplanninghorizon.ThisisachievedbyadoptingtheprinciplesofLCA,expandingthenetworkboundariestoincorporateasetofNPlifecyclestagesandusingtheEco-Indicator99method[35]toassesstheenvironmentalimpactofthenetwork.ThisrequiresthecharacterizationofasetofNBenvironmentalburdensintoasetofNEimpactcategories/indicatorsovertheentirehorizon.安裝所需的投資的預(yù)計凈現(xiàn)值（NPV）作為網(wǎng)絡(luò)盈利能力的衡量方法，擴(kuò)展和經(jīng)營工廠作為經(jīng)濟(jì)目標(biāo)函數(shù)。相反的，生態(tài)目標(biāo)函數(shù)是根據(jù)整個規(guī)劃期內(nèi)網(wǎng)絡(luò)的運(yùn)營導(dǎo)致的環(huán)境影響來確定的。這是通過采用生命周期評價的原則和使用環(huán)保指標(biāo)99方法來實(shí)現(xiàn)的。LCA原則是擴(kuò)大網(wǎng)絡(luò)界限納入NP生命周期階段，而環(huán)保指標(biāo)99方法是用來評價網(wǎng)絡(luò)的環(huán)境影響。這需要將整個期間內(nèi)的環(huán)境負(fù)擔(dān)設(shè)置成一系列影響類別/指標(biāo)。3.Mathematicalmodel3.1.Plantlocation,capacityexpansionandmaterialbalances工廠選址，能力擴(kuò)展和物料平衡TheproblemisformulatedsuchthatthevariableFjstrepresentsthetotalcapacityduringtimeintervaltofplantjbeingsituatedatsites.ExistingplantcapacitiesareenteredintothemodelbyspecifyingFjstattimet=0.TheexpansionofplantcapacitiesduringtimeintervaltisrepresentedbythevariableFEjst.Foraplantthathasnotbeeninstalledduringprevioustimeintervals(i.e.whichhaszerocapacityattimet=0),thefirstnon-zerovalueofFEjstduringtheplanninghorizoncorrespondstotheinstallationcapacityoftheplant.Assuch,nodistinctionisnecessarybetweencapacitylocationandexpansion.FEjstcapturesbothscenariosand,therefore,reflectsanyformofcapacityincreaseofaparticularplant.Throughoutthesubsequentmodeldescriptionthetermscapacityexpansionsandlocationwillbeinterchangedunlessadistinctionisexplicitlymade.Fjst代表位于s的工廠j時間段t總能力。模型已有的工廠能力是指定時間t=0時具體Fjst的值。T階段工廠擴(kuò)展能力用變量FEjst表示。先前時間階段內(nèi)沒有安裝的工廠（如在t=0時能力為0），規(guī)劃期內(nèi)FEjst第一個非零值與工廠安裝容量有關(guān)。同樣的，沒必要區(qū)分工廠的位置和能力擴(kuò)展。兩種方案的FEjst捕獲反應(yīng)特定工廠的能力增加。在整個后續(xù)模型的能力擴(kuò)展和位置描述可以互換，除非明確提出有區(qū)別。ControloverthechangesinthecapacitiesovertheplanninghorizonisachievedthroughthebinaryvariableYjst,indicatingwhetherthecapacityofplantjatsitesisincreasedduringtimeintervalt.Theconstraintsinvolvingthesevariablesare:用0,1變量Yjst來控制規(guī)劃期間內(nèi)的能力變化，表明t階段內(nèi)位置s的工廠j的能力增加。變量限制條件為：Inthecasewhenanexpansionisnotperformedduringtimeperiodt,YjsttakesonavalueofzeroandEq.(1)forcestheamountbywhichthecapacityisincreasedduringthatperiod,FEjst,tozero.Alternatively,whenthecapacityisincreased(Yjst=1),Eq.(1)ensuresthatitoccurswithinphysicallymeaningfullimits.Assuch,themodelisoftheCapacitatedPlantLocationProblemtype.Eq.(2)merelyensuresthatthetotalcapacityisupdatedbytheincreasedamountduringtimeintervalt.Thenumberofinstallations/expansionscanalsobecontrolleddependingonthespecificrequirementsofthestudybyincluding:擴(kuò)張沒有在時間t內(nèi)發(fā)生，Yjst值為0，公式（1）使那個時間段內(nèi)能力增加量為0。或者，當(dāng)能力增加的時候（Yjst=1），公式（1）確保其在物理意義范圍內(nèi)發(fā)生。因此，該模型是約束的選址問題類型。公式（2）僅僅確保在時間段t內(nèi)，總?cè)萘扛?。通過研究的具體要求，控制安裝/擴(kuò)張量：Eq.(3)limitsthenumberofexpansionsofaparticulartechnologyataspecificsiteovertheentireplanninghorizon.Inthemostrelaxedcasewherenolimitsareplacedonthenumberofexpansions,thelowerboundissettozerowiththeupperboundbeingJUjs=NT.公式（3）限制整個規(guī)劃期內(nèi)具體地點(diǎn)的特定技術(shù)的擴(kuò)張數(shù)量。最不嚴(yán)格的的情況是擴(kuò)張數(shù)量沒有約束限制，下限為0，上限為JUjs=NT。Demandnodemcanonlybesuppliedbysitesduringintervaltifatleastoneplanthaspreviouslybeeninstalledonthesite.ThisisachievedusingthebinaryvariableXsmt,dictatingwhetheratransportationconnectionisestablishedbetweensitesandmarketm,asfollows:在時間t內(nèi)，需求節(jié)點(diǎn)m只由地點(diǎn)s供應(yīng)，如果在該位置至少已經(jīng)設(shè)置一個工廠。這個可以通過0,1變量Xsmt達(dá)到，規(guī)定在地點(diǎn)s和市場m間是否建立一個交通站點(diǎn)，內(nèi)容如下：Marketsrequiringsinglesourcing,i.e.onlyonesiteisallowedtoserveit,canalsobeaccommodated:市場需要單一的來源，如只允許唯一的地點(diǎn)服務(wù)于它，提供如下：whereMSSisthesubsetofmarketsrequiringsinglesourcing.MSS是需要單一來源的市場的子集。Alternatively,ifthenumberofsitesservingaparticulardemandnodehastobemoreorlessthanaspecifiedamountthenthefollowingconstraintscanbeused:或者，如果供應(yīng)特定需求的節(jié)點(diǎn)的地點(diǎn)數(shù)比指定數(shù)量多或者少，可以使用以下的約束Finally,thetransportationofproductifromsitestomarketmcanonlyexistifaconnectionhasbeenestablishedduringaparticulartimeinterval:最終，如果在特定時間段站點(diǎn)已經(jīng)建立，則從地點(diǎn)s到市場m的產(chǎn)品i的運(yùn)輸存在。Thedemandofaparticularproductatnodemneedstobesatisfiedwithinboundswhilerawmaterialscanonlybepurchasedaccordingtotheiravailabilities:節(jié)點(diǎn)m的一個特定產(chǎn)品的需求需要在界限內(nèi)被滿足，而原材料只能根據(jù)自己的需要購買：Attheoutgoingdistributionnodeofeachsite-asshownonFig.1-thefollowingmaterialbalancecanbeappliedlinkingtheproductionratesofthevariousplantstothedistributionfromsitestomarkets:在每個地點(diǎn)的的向外配送節(jié)點(diǎn)-在圖1中所示-以下物料平衡可用于將各個工廠的生產(chǎn)率連接到地點(diǎn)到市場的配送。Similarlyamaterialbalancecanbewrittenatthereceivingnodeofeachsiterelatingtheusageofrawmaterialsbyeachplantwithinasitetotheamountdeliveredtotheentiresite:同樣的，物料平衡可以寫在與每個工廠的原材料使用有關(guān)的每個地點(diǎn)的接受節(jié)點(diǎn)，然后傳送到整個網(wǎng)絡(luò)中去：Foreachplant,theproductionrateofallproductscannotexceedtheinstalledcapacitywhileitalsohastobeensuredthataminimumdesiredpercentage,,oftheavailableinstalledcapacityisutilized:每個工廠，所有產(chǎn)品的生產(chǎn)率不能超過裝機(jī)容量，但是要同時確?，F(xiàn)有裝機(jī)容量使用率的最低所需的百分比Limitscanalsobeplacedontheproductionrateofeachplantdependingonthephysicalconstraintsofthetechnologyitemploys:限制條件也設(shè)置在每個工廠的生產(chǎn)率上，這個依賴所用技術(shù)的物理約束。Throughtheuseofutilizationfactorsforeachtypeoftechnologyj,balancesfortheconversionofrawmaterialsintoproductscanbewritten.Foranumberofwidelyusedpetrochemicalprocessingtechnologies,estimatesofmaterialbalancesfortheproductionofaunitofmainproductaredocumented[36].Thisallowsderivationofaparameter,,thatrepresentstheamountofrawmaterialrrequiredfortheunitproductionofproductiusingtechnologyj.Assumingthatsuchlinearrelationshipsholdovertherangeofproductionrates,theindividualplantmassbalancesare:通過每個技術(shù)類型j的利用系數(shù)的使用，從原料到產(chǎn)品的轉(zhuǎn)換平衡可以記錄下來。對于許多廣泛使用的石油化工加工技術(shù)，單位主要產(chǎn)品的物料平衡生產(chǎn)預(yù)算都有記錄[36]。這允許推導(dǎo)出一個參數(shù)，表示利用技術(shù)j生產(chǎn)單位產(chǎn)品的原材料r使用量。假設(shè)這個線性關(guān)系在整生產(chǎn)率范圍內(nèi)都保持，則每個工廠質(zhì)量平衡如下：3.2.EnvironmentalimpactassessmentThefirststepintheLCAprocedureistheGoalandScopeDefinitionwherebythefunctionalunitandsystemboundaryofthestudyaredefined.Forthemodeldevelopedhere,theboundaryaroundthenetworksuperstructuredepictedinFig.1isexpandedtoincludethefollowingsetoflifecyclestages:LCA過程中的第一步是定義目的和范圍，界定各功能單元和系統(tǒng)研究邊界。這里提出的，圖1中描述的網(wǎng)絡(luò)上層建筑的界限擴(kuò)大到包括以下生命周期階段：wherePRijistheforegroundproductionprocessofproductiusingtechnologyj,TRisthetransportationofrawmaterialsfromsupplierstosites,TPisthetransportationofproductsfromsitestomarkets,UTisthegenerationandsupplyofutilitiesdemandedbytheplants,andRMristheproductionofrawmaterialr.Thefunctionalunitfortheoverallsystemisdefinedasthedeliveryofthefinalchemicalproductstothemarketsovertheentireplanninghorizon.Theassessment/r/