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时间:2019-08-06
《An algorithm for hoist scheduling》由会员上传分享,免费在线阅读,更多相关内容在学术论文-天天文库。
1、INT.J.PROD.RES.,1994,VOL.32,No.3,501-516AnalgorithmforhoistschedulingproblemsY.YIHThispaperproposesanalgorithmforhoistschedulingproblemsinaflexiblePCBelectroplatinglinewherethereisnobufferamongworkstations.Duetoitschemicalprocessnature,theprocessingtimeshavetobecontrolledwithinaspecifiedrange(i.
2、e.betweenamaximumprocessingtimeandaminimumprocessingtime).Theproductwillbecomedefectiveifthisconstantisviolated.Theobjectiveistomaximizethroughputwithnodefectiveproduct.Theproposedalgorithmschedulesjobsenteringthesystembasedonthespecifiedrangeofprocessingtime.Asimulationstudyshowsthattheproposed
3、algorithmoutperformsthebasicalgorithmthatschedulesjobsbasedontheminimumprocessingtimes.1.IntroductionMaterialhandlinghoistsarecommonlyusedinsmeltingandplatingprocessestotransportmaterialsamongworkstations(e.g.furnaces,chemicaltanks).Thecontrolandscheduleofsuchhoistsisverycrucialtothesystemperfor
4、mance,especiallywheretherearechemicalprocessesinvolved.Inprintedcircuitboard(PCB)manufacturingfacilities,veryoftentheplatingprocessisoneofthemajorbottlenecks.Thehoistschedulingproblemsareusuallyverycomplex.ThehoistschedulingproblemhasbeenproventobeNP-completeareusuallyverycomplex.Thehoistschedul
5、ingproblemhasbeenproventobeNP-completeevenifthereisonlyonehoistandoneproducttypeinthesystem(LeiandWang1989).Thisresearchismotivatedbyasingle-hoistschedulingprobleminaflexibleprintedcircuitboard(PCB)electroplatingsystemasshowninFig.I.Thehoisttransportsmaterialsthroughaseriesofchemicaltanks.Jobs(P
6、CBs)randomlyarriveatthesystemandhavetogothroughtheworkstationssequentiallyfromlefttorightwhileskippingworkstationsisallowed.Inaddition,eachjobhasitsspecifictimewindows(specifiedbyaminimumprocessingtimeandamaximumprocessingtime)forprocessingineachworkstation.Iftheprocessingtimeforajobinaworkstati
7、ondoesnotreachtheminimumprocessingtimeorexceedthemaximumprocessingtime,thejobwillbecomeadefect.Thehoistisinchargeoftransportingjobs,oneatatime,throughtheworkstationscorrespondingwiththoseboundedprocessingtimes.Thetravellings
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