简介：Weconsidertheclassicalpolicyiterationmethodofdynamicprogramming(DP),whereapproximationsandsimulationareusedtodealwiththecurseofdimensionality.Wesurveyanumberofissues:convergenceandrateofconvergenceofapproximatepolicyevaluationmethods,singularityandsusceptibilitytosimulationnoiseofpolicyevaluation,explorationissues,constrainedandenhancedpolicyiteration,policyoscillationandchattering,andoptimisticanddistributedpolicyiteration.Ourdiscussionofpolicyeva...

简介：ThispaperproposesandevaluatestwoimprovedPetrinet(PN)-basedhybridsearchstrategiesandtheirapplicationstoflexiblemanufacturingsystem(FMS)scheduling.Thealgorithmsproposedinsomepreviouspapers,whichcombinePNsimulationcapabilitieswithA*heuristicsearchwithinthePNreachabilitygraph,maynotfindanoptimumsolutionevenwithanadmissibleheuristicfunction.Toremedythedefectsanimprovedheuristicsearchstrategyisproposed,whichadoptsadifferentmethodforselectingthepromisingmarkingsandreservestheadmissibilityofthealgorithm.Tospeedupthesearchprocess,anotheralgorithmisalsoproposedwhichinvokesfasterterminationconditionsandstillguaranteesthatthesolutionfoundisoptimum.TheschedulingresultsarecomparedthroughasimpleFMSbetweenouralgorithmsandthepreviousmethods.Theyarealsoappliedandevaluatedinasetofrandomly-generatedFMSswithsuchcharacteristicsasmultipleresourcesandalternativeroutes.

简介：Thispaperdealswiththevectorcontrol,includingboththedirectvectorcontrol(DVC)andtheindirectvectorcontrol(IdVC),ofinductionmotors.ItiswellknownthattheestimationofrotorfluxplaysafundamentalroleintheDVCandtheestimationofrotorresistanceisvitalintheslipcompensationoftheIdVC.Intheseestimations,theprecisionissignificantlyaffectedbythemotorresistances.Therefore,onlineestimationofmotorresistancesisindispensableinpractice.Forafastestimationofmotorresistances,itisnecessarytoslowdowntheconvergencerateofthecurrentestimate.Ontheotherhand,forafastestimationoftherotorflux,itisnecessarytospeedupitsconvergencerate.Itisverydifficulttorealizesuchatrade-offinconvergenceratesinafullorderobserver.Inthispaper,weproposetodecouplethecurrentobserverfromthefluxobserversoastorealizeindependentconvergencerates.Then,theresistanceestimationalgorithmisappliedtobothDVCandIdVC.Inparticular,intheapplicationtoIdVCthefluxobserverneedsnotbeused,whichleadstoasimplerstructure.Meanwhile,independentconvergenceratesofcurrentobserverandfluxobserveryieldanimprovedperformance.Asuperiorperformanceinthetorqueandfluxresponsesinbothcasesisverifiedbynumeroussimulations.