简介:Controlofsupersonicflowfieldswithshockwaveisimportantforsomeindustrialfields.Therearemanystudiesforcontrolofthesupersonicflowfieldsusingactiveorpassivecontrol.Whennon-equilibriumcondensationoccursinasupersonicflowfield,theflowisaffectedbylatentheatreleased.Manystudiesforthecondensationhavebeenconductedandthecharacteristicshavebeenalmostclarified.Further,itwasfoundthatnon-equilibriumcondensationcancontroltheflowfield.Inthesestudies,thecondensationoccursacrossthepassageoftheflowfieldanditcausesthetotalpressurelossintheflowfield.However,localoccurrenceofnon-equilibriumcondensationintheflowfieldmaychangethecharacteristicsoftotalpressurelosscomparedwiththatbythecondensationacrossthepassageofthenozzleandtherearefewforresearchesoflocallyoccurrednon-equilibriumcondensationinsupersonicflowfield.Thepurposeinthepresentstudyistoclarifytheeffectoflocaloccurrenceofnon-equilibriumcondensationonthetransonicflowfieldinanozzlewithacircularbump.Asaresult,localoccurrenceofnon-equilibriumcondensationreducedtheshockstrengthandtotalpressurelossinthetransonicflowfieldbyflowingthemoistairfromtrailingedgeofthecircularbumptothemainstream.
简介:Thechargingcharacteristicsofthevalve-regulatedleadacid(VRLA)batterydrivenbysolarenergywereexperimentallystudiedthroughthepressure-controlmethodinthispaper.Theaimsoftheresearchweretoincreasechargingefficiencytomakethemostofsolarenergyandtoimprovechargingqualitytoprolonglifeofbattery.Thechargingprocessofa12V12A·hVRLAbatteryhasbeentestedunderthemodeofastand-alonephotovoltaic(PV)system.Resultsshowthatthepressure-controlmethodcaneffectivelycontrolPVchargingoftheVRLAbatteryandmakethebestofPVcellsthroughthemaximumpowerpointtracking(MPPT).ThedamageofVRLAbatterybyexcessoxygenaccumulationcanbeavoidedthroughtheinnerpressurecontrolofVRLAbattery.Parameterssuchassolarradiationintensity,chargingpower,innerpressureofthebattery,andchargingcurrentandvoltageduringthechargingprocessweremeasuredandanalyzed.
简介:Atheoreticalmodelingapproachaswellasanunsteadyanalyticalmethodisusedtostudyaerodynamiccharacteristicsofwingflappingwithasymmetricstroke-cyclesinconnectionwithanobliquestrokeplaneduringinsectforwardflight.Itisrevealedthattheaerodynamicasymmetrybetweenthedownstrokeandtheupstrokeduetostroke-asymmetricalflappingisakeytounderstandtheflowphysicsofgenerationandmodulationoftheliftandthethrust.Predictedresultsforexamplesofgivenkinematicsvalidatemorespecificallysomeviewpointsthatthewingliftismoreeasilyproducedwhentheforwardspeedishigherandthethrustisharder,andtheliftandthethrustaregeneratedmainlyduringdownstrokeandupstroke,respectively.Theeffectsofthreecontrollingparameters,i.e.theanglesoftiltedstrokeplane,thedifferentdownstrokedurationratios,andthedifferentanglesofattackinbothdown-andup-stroke,arefurtherdiscussed.Itisfoundthatlargerobliqueanglesofstrokeplanesgeneratelargerthrustbutsmallerlift;largerdownstrokedurationratiosleadtolargerthrust,whilemakinglittlechangeinliftandinputaerodynamicpower;andagain,asmallincreaseoftheangleofattackindownstrokeorupstrokemaycauseremarkablechangesinaerodynamicperformanceintherelevantstroke.
简介:AsoneofthekeyunitsofspaceCCDcamera,thetemperaturerangeandstabilityofCCDcomponentsaffecttheimage’sindexes.Reasonablethermaldesignandrobustthermalcontroldevicesareneeded.Onekindoftemperaturecontrolloopheatpipe(TCLHP)isdesigned,whichhighlymeetsthethermalcontrolrequirementsofCCDcomponents.InordertostudythedynamicbehaviorsofheatandmasstransferofTCLHP,particularlyintheorbitalflightcase,atransientnumericalmodelisdevelopedbyusingthewell-establishedempiricalcorrelationsforflowmodelswithinthreedimensionalthermalmodeling.Thetemperaturecontrolprincipleanddetailsofmathematicalmodelarepresented.Themodelisusedtostudyoperatingstate,flowandheatcharacteristicsbasedupontheanalysesofvariationsoftemperature,pressureandqualityunderdifferentoperatingmodesandexternalheatfluxvariations.TheresultsindicatethatTCLHPcansatisfythethermalcontrolrequirementsofCCDcomponentswell,andalwaysensuregoodtemperaturestabilityanduniformity.Bycomparisonbetweenflightdataandsimulatedresults,itisfoundthatthemodelistobeaccuratetowithin1℃.ThemodelcanbebetterusedforpredictingandunderstandingthetransientperformanceofTCLHP.
简介:Beamhalo-chaosinhigh-currentacceleratorshasbecomeakeyconcernedissuebecauseitcancauseexcessiveradioactivityfromtheacceleratorsthereforesignificantlylimitstheirapplicationsinindustry,medicine,andnationaldefense.Somegeneralengineeringmethodsforchaoscontrolhavebeendevelopedinrecentyears,buttheygenerallyareunsuccessfulforbeamhalo-chaossuppressionduetomanytechnicalconstraints.Beamhalo-chaosisessentiallyaspatiotemporalchaoticmotionwithinahighpowerprotonaccelerator.Inthispaper,someefficientnonlinearcontrolmethods,includingwaveletfunctionfeedbackcontrolasaspecialnonlinearcontrolmethod,areproposedforcontrollingbeamhalo-chaosunderfivekindsoftheinitialprotonbeamdistributions(i.e.,Kapchinsky-Vladimirsky,fullGauss,3-sigmaGauss,water-bag,andparaboladistributions)respectively.Particles-in-cellsimulationsshowthataftercontrolofbeamhalo-chaos,thebeamhalostrengthfactorisreducedtozero,andotherstatisticalphysicalquantitiesofbeamhalo-chaosaredoublyreduced.Themethodswedevelopedisveryeffectiveforsuppressionofprotonbeamhalo-chaosinaperiodicfocusingchannelofaccelerator.Somepotentialapplicationofthebeamhalo-chaoscontrolinexperimentsisfinallypointedout.
简介:BasedontheFloquettheoryonordinarydifferentialequationswithperiodicallyvariablecoefficientsandthebifurcationapproachtononlinearequations,anumericalapproachtodeterminingthestabilityregionofcontrolparametersisestablishedforadynamiccontrolsystemcomposedofamovingbodylevitatedmagneticallyoverflexibleguideways.Thesystemisnonlinearlycoupledamongtheelasticdeformationofguideways,disturbancethelevitationpositionofthebodyandelectromagneticcontrolforces.Thenumericalsimulationisgivenforthesysteminthecaseinwhichthecontrolparametersaretakenwithinandoutofthestabilityregionrespectively.Resultsshowthatthisapproachisreliable.
简介:Magneto-rheologicalvisco-elastomer(MRVE)asanewsmartmaterialdevelopedinrecentyearshasseveralsignificantadvantagesovermagneto-rheologicalliquid.Theadjustabilityofstructuraldynamicstorandomenvironmentalexcitationsisrequiredinvibrationcontrol.MRVEcansupplyconsiderablyadjustabledampingandstiffnessforstructures,andtheadjustmentofdynamicpropertiesisachievedonlybyappliedmagneticfieldswithchangelessstructuredesign.IncreasingresearchesonMRVEdynamicproperties,modeling,andvibrationcontrolapplicationarepresented.RecentadvancesinMRVEdynamicpropertiesandstructuralvibrationcontrolapplicationincludingcompositestructuralvibrationmitigationunderuniformmagneticfields,vibrationresponsecharacteristicsimprovementthroughharmonicparameterdistribution,andoptimalboundedparametriccontroldesignbasedonthedynamicalprogrammingprinciplearereviewed.RelevantmainmethodsandresultsintroducedarebeneficialtounderstandingandresearchesonMRVEapplicationanddevelopment.
简介:TheInternetevolvestoincorporatevery-high-bandwidthopticallinksandmorelarge-delaysatellitelinks.TCPfacesnewchallengesinthisuniqueenvironment.TheoryandexperimentsshowedthatTCPbecomesinefficientandispronetobeunstableastheper-flowproductofbandwidthandlatencyincreases,regardlessofthequeuingscheme.Variable-structurecongestionControlProtocol(VCP)isproposedtoaddresstheseproblems.However,VCPhasproblemintermsofconvergencetime,i.e.,ittakesalongtimeforanewVCPflowtoachievefairbandwidthallocationiftheexistingVCPflowshavelargecon-gestionwindows.ThispaperproposedanExtendedVariable-structurecongestionControlProtocol(EVCP),whichadoptedaconvergencecontroller.Thebasicideaofconvergencecontrolleristhatifaflowhaslargerwindowthanitsfairwindow,itscongestionwindowshouldbedecreasedmoreaggressivelythanusualinMultiplicativeDecrease(MD)phase.SimulationsshowedthatEVCPhasbetterperformanceintermsofconvergencetimewhilekeepingtheadvantagesofVCP.
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简介:我们考虑在基于测量的反馈控制和隧道被考虑的decoherence的二个原型的类下面受到一条噪音隧道的一个开的量系统:阶段抑制并且概括振幅抑制。基于量轨道理论,我们面对反馈控制为减少的系统的动力学获得一个扩大主人方程。为一个qubit系统我们经分解解决这个主人方程并且获得州的向量动力学的解决方案。然后,我们为准备任意的量建议一个有效反馈控制计划纯状态。我们也学习怎么有效地保护二个nonorthogonal状态,并且发现有不偏的基础的射影的测量不为这项任务是最佳的,当有偏导的基础的弱测量能认识到二个nonorthogonal状态的最好的保护时。而且,在反馈过程的无效也被讨论。
简介:Thispaperaddressesamaster-slavesynchronizationstrategyforcomplexdynamicsystemsbasedonfeedbackcontrol.Thisstrategyisappliedto3-DOFplanarmanipulatorsinordertoobtainsynchronizationinsuchcomplicatedaschaoticmotionsofend-effectors.AchaoticcurveisselectedfromDuffingequationasthetrajectoryofmasterend-effectorandapiecewiseapproximationmethodisproposedtoaccuratelyrepresentthischaotictrajectoryofend-effectors.Thedynamicalequationsofmaster-slavemanipulatorswithsynchronizationcontrollerarederived,andtheLyapunovstabilitytheoryisusedtodeterminethestabilityofthiscontrolledsynchronizationsystem.Innumericalexperiments,thesynchronousmotionsofend-effectorsaswellasthreejointanglesandtorquesofmaster-slavemanipulatorsarestudiedunderthecontroloftheproposedsynchronizationstrategy.Itisfoundthatthepositivegainmatrixaffectstheimplementationofsynchronizationcontrolstrategy.Thissynchronizationcontrolstrategyprovesthesynchronization'sfeasibilityandcontrollabilityforcomplicatedmotionsgeneratedbymaster-slavemanipulators.
简介:Theactivecontrolofvibrationforabeamsubjectedtomulti-disturbancesisinvestigatedbasedonwavepropagatingsuppression.Inthiscontrolsystem,therearethesamenumbersofthesensors,thesignalinputtingtothecon-trollerandthedisturbances,butthereisonlyonecontroller.Itisalocalcontrolsystem,thesystemparametersdependonlyonthecharacteristicsofthestructureboundedbythesensorsandthecontroller,andweneednottakeintoaccounttheboundaryconditionsandthepropertiesofstructuresoutsideofthisfield.Thesys-temisefficientwhenastructurevibratesinmiddleandhighfrequencyregions.Somecontroldesignrulesaredevelopedfromthecalculationresults.
简介:Abstract.OnthebasisofclassificationofgeographicalpropertiesarollingdevelopmentgoalprogrammingmodelisformulatedincorrespondencewiththeecopatterngroupinFour-LakeArea.Inthismodel,thecontrolofschistosomiasisandstrengthen-Lugofthedrainage-storagefunctionarebothregardedasecologicalmeasuresduringtheprocessofmulti-year(r0)ecologicaleconomicrollingdevelopmenttomaketheecoagrlculturalsysteminthisareaintoastablyoperating,ordered,andgoodcyclicsystemunderthesupportofsomecontrollablefactors.
简介:Theoptimalarrangementofviscoelasticdampers(VEDs)usedtolinktwoadjacentshear-typestructuresunderseismicexcitationwasinvestigated.Atwo-stepoptimaldesignmethodisproposed.First,optimalparameterexpressionsoftheKelvinmodelareusedtocalculatetheoptimalstiffnessanddampingcoefficientoftheVEDs.Then,usingthetwo-stepoptimaldesignmethod,takingthequadraticperformanceindexastheoptimizationobjective,theoptimalarrangementofthedampersisdetermined.GeneralrulesabouttheoptimalarrangementoftheVEDswereobtained.Theresultsshowthattheplacementofonlyonedamperbetweentwoadjacentshear-typestructuresshouldbeavoided;ifmorethanonedamperisused,theyshouldbedistributedonthetopandlowerfloorsofthestructures.Optimizationofthenumberofdampershadlittleeffectonresponsereduction.Themostimportantfactorwastheoptimizationoftheplacementofthedampers.Throughcomparativestudy,forbuildingsofequalandunequalheights,theoptimalparametersofdampersfromparametricstudieswereshowntomatchthetheoreticalresultsfordifferentnumbersandplacementsofdampers.Thelevelofresponsereductionwasshowntobesensitivetothedampingcoefficientofthedampers.
简介:TheinverseFaradayeffectinducedinmagneticfilmsbyultrashortlaserpulsesallowsexcitationandcontrolofspinsatgigahertzandsub-terahertzfrequencies.Thefrequencyoftheopticallyexcitedmagnetizationprecessioniseasilytunablebytheexternalmagneticfield.Ontheotherhand,theinitialphaseoftheprecessionmarginallydependsonthemagneticfield.Herewedemonstrateanapproachforthecontroloftheprecessionphasebyvariationofthepumpbeamdirection.Inparticular,weconsiderthecasewhenthemagnetizationprecessionisexcitedbyobliquelyincidentpumppulsesinamagneticdielectricfilmplacedinthein-planemagneticfield.Theoreticalconsiderationpredictsthattheinitialphaseshouldappearforanon-zeroin-planecomponentofthepumpwavevectororthogonaltotheexternalmagneticfield.Experimentalstudiesconfirmthisconclusionandrevealthatthephasegrowswithincreaseofthein-planewavevectorcomponent.Variationofphaseby15degisdemonstrated.Potentially,thephasecouldbechangedevenmorepronouncedlybymorethan90deg.Thisworkprovidesasimplewayforadditionalmanipulationwithopticallyexcitedmagnetizationdynamics,whichisofimportancefordifferentspintronicapplications.
简介:传统的被动吸收器在一个狭窄、肯定的频率乐队以内是充分有效的。解决这个问题,推迟时间的加速反馈被介绍把一个被动吸收器变换成活跃的。两固有并且故意的时间延期被包括。前者主要来自信号获得并且处理,计算,并且适用使活动力量,和它的值被修理。后者在控制器被介绍,并且它的价值是活跃地可调节的。第一,机械模型被建立,频率反应方程被获得。稳定性的区域在控制参数的飞机被描出。第二,控制帕拉的设计计划--米被执行帮助选择反馈获得和时间延期的值。第三,试验性的研究被进行。否定、积极的反馈控制的效果被调查。试验性的结果证明控制参数的合适的选择可以拓宽颤动吸收的有效频率乐队。而且,当被动吸收器完全失败时,推迟时间的吸收器极大地压制主要系统的反响的反应。试验性的结果在对理论预言和数字模拟的好同意。
简介:Basedonthediscretetimemethod,aneffectivemovementcontrolmodelisdesignedforagroupofhighspeedtrainsonarailnetwork.Thepurposeofthemodelistoinvestigatethespecifictrafficcharacteristicsofhigh-speedtrainsundertheinterruptionofstochasticirregularevents.Inthemodel,thehigh-speedrailtrafficsystemissupposedtobeequippedwiththemoving-blocksignallingsystemtoguaranteemaximumtraversingcapacityoftherailway.Tokeepthesafetyoftrains’movements,someoperationalstrategiesareproposedtocontrolthemovementsoftrainsinthemodel,includingtractionoperation,brakingoperation,andentering-stationoperation.Thenumericalsimulationsshowthatthedesignedmodelcanwelldescribethemovementsofhigh-speedtrainsontherailnetwork.Theresearchresultscanprovidetheusefulinformationnotonlyforinvestigatingthepropagationfeaturesofrelevantdelaysundertheirregulardisturbancebutalsoforreroutingandreschedulingtrainsontherailnetwork.