简介:Thispaperstudiesastochasticallyforcedchemostatmodelwithfeedbackcontrolinwhichtwoorganismscompeteforasinglegrowth-limitingsubstrate.Inthedeterministiccounterpart,previousresearchesshowthatthecoexistenceoftwocompetingorganismsmaybeachievedasastablepositiveequilibriumorastablepositiveperiodicsolutionbydierentfeedbackschedules.Inthestochasticcase,basedonthestochasticsensitivityfunctiontechnique,weconstructtheconfidencedomainsfordierentfeedbackscheduleswhichallowustofindtheconfigurationalarrangementsofthestochasticattractorsandanalyzethedispersionoftherandomstatesofthestochasticmodel.
简介:ThispapergivesatutorialonhowtoproveLyapunovtypecriteriabyoptimalcontrolmethods.Firstly,weconsiderstabilitycriteriaonHill'sequationswithnonnegativepotential.Byoptimalcontrolmethodsdevelopedin1990s,weobtainseveralstabilitycriteriaincludingLyapunov'scriterion,Ne..gauzandLidski'scriterion.Secondly,wepresentstabilitycriteriaonHill'sequationswithsign-changingpotentialinwhichBrog'scriterionandKrein'scriterionareincluded.
简介:Inthethree-phasetrafficflowstudies,thetrafficflowcharacteristicatthebottlenecksectionisahotspotintheacademicfield.Thecontroversyaboutthecharacteristicsofthesynchronizedflowatbottleneckisalsothemaincontradictionbetweenthethree-phasetrafficflowtheoryandthetraditionaltrafficflowtheory.Undertheframeworkofthree-phasetrafficflowtheory,thispapertakestheon-rampasanexampletodiscussthetrafficflowcharacteristicsatthebottlenecksection.Inparticular,thispapermainlyconductsthemicro-analysistotheeffectoflanechangeunderthetwolaneconditions,aswellastheeffectoftheon-ramponthemainlinetrafficflow.Itisfoundthatwhenthemainroadflowislow,thegreatertheon-rampinflowrate,thehighertheaveragespeedofthewholeroadsection.Astheprobabilityofvehiclesenteringfromtheon-rampincreases,theflowandtheaveragespeedofthemainroadaregraduallystabilized,andthentheon-rampinflowvehiclesnolongerhaveasignificantimpactonthetrafficflow.Inaddition,thispaperfocusesonthevelocitydisturbancegeneratedattheon-ramp,andproposesthecorrespondingon-rampcontrolstrategybasedonit,andthesimulationverifiedthatthecontrolstrategycanreasonablycontrolthetrafficflowbytheon-ramp,whichcanmeetthecontrolstrategyrequirementstosomeextent.
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简介:Inthispaper,weproposeaLotka-Volterraprey-predatorsystemwithdiscretedelaysandfeedbackcontrol.Firstly,weshowthatsolutionofthesystemisbounded.Secondly,weobtainsufficientconditionfortheglobalstabilityoftheuniquepositiveequilibriumtothesystem.
简介:Thispaperproposesanultra-modifiedSSA(symmetricsequencealgorithm)ofspacevectormodulationofMC(matrixconverter).Theultra-modifiedtechniqueimprovesthedrawbacksofthemodifiedonewhereitprovidesareductionofthetotalharmonicdistortionforbothoutputvoltageandcurrent.AlsothispaperproposesamodifiedfeedforwardcontrolleroftheMCwithindirectspacevectormodulation.Themodifiedfeedforwardprovidesasolutionforthechangeintheoutputvoltageduetochangeinwindspeed,whereitprovidesaconstantoutputvoltagewithconstantfrequencyevenifthewindspeedchanged.SomeoftheadvantagesofMCareintroducedinthispaper.TheseadvantagesrepresentedintheoutputfrequencyofMCwhichmaybegreaterthantheinputfrequency,controllingrmsvalueoftheoutputvoltageandtheabilitytocontroltheIDF(inputdisplacementfactor).Attheendofthispapersimulationandexperimentalresultsareintroducedwhichgiveapreciseprooftotheproposedalgorithms.
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简介:TheinverseFaradayeffectinducedinmagneticfilmsbyultrashortlaserpulsesallowsexcitationandcontrolofspinsatgigahertzandsub-terahertzfrequencies.Thefrequencyoftheopticallyexcitedmagnetizationprecessioniseasilytunablebytheexternalmagneticfield.Ontheotherhand,theinitialphaseoftheprecessionmarginallydependsonthemagneticfield.Herewedemonstrateanapproachforthecontroloftheprecessionphasebyvariationofthepumpbeamdirection.Inparticular,weconsiderthecasewhenthemagnetizationprecessionisexcitedbyobliquelyincidentpumppulsesinamagneticdielectricfilmplacedinthein-planemagneticfield.Theoreticalconsiderationpredictsthattheinitialphaseshouldappearforanon-zeroin-planecomponentofthepumpwavevectororthogonaltotheexternalmagneticfield.Experimentalstudiesconfirmthisconclusionandrevealthatthephasegrowswithincreaseofthein-planewavevectorcomponent.Variationofphaseby15degisdemonstrated.Potentially,thephasecouldbechangedevenmorepronouncedlybymorethan90deg.Thisworkprovidesasimplewayforadditionalmanipulationwithopticallyexcitedmagnetizationdynamics,whichisofimportancefordifferentspintronicapplications.
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简介:Anall-opticallight–control–lightfunctionalitywiththestructureofamicrofiberknotresonator(MKR)coatedwithtindisulfide(SnS2)nanosheetsisexperimentallydemonstrated.TheevanescentlightintheMKR[witharesonanceQof~59,000andanextinctionratio(ER)of~26dB]isexploitedtoenhancelight–matterinteractionbycoatingatwo-dimensionalmaterialSnS2nanosheetontoit.Thankstotheenhancedlight–matterinteractionandthestrongabsorptionpropertyofSnS2,thetransmittedopticalpowercanbetunedquasi-linearlywithanexternalvioletpumplightpower,whereatransmittedopticalpowervariationrateΔTwithrespecttothevioletlightpowerof~0.22dB∕mWisobtained.Inaddition,theMKRstructurepossessingmultipleresonancesenablesadirectexperimentaldemonstrationoftherelationshipbetweenresonanceproperties(suchasQandER),andtheobtainedΔTvariationratewithrespecttothevioletlightpower.ItverifiesexperimentallythatahigherresonanceQandalargerERcanleadtoahigherΔTvariationrate.Intermsoftheoperatingspeed,thisdevicerunsasfastas~3.2ms.Thiskindofall-opticallight–control–lightfunctionalstructuremayfindapplicationsinfutureall-opticalcircuitry,handheldfibersensors,etc.