简介:Apotentialreductionalgorithmisproposedforoptimizationofaconvexfunctionsubjecttolinearconstraints.Ateachstepofthealgorithm,asystemoflinearequationsissolvedtogetasearchdirectionandtheArmijo'sruleisusedtodetermineastepsize.Itisprovedthatthealgorithmisgloballyconvergent.Computationalresultsarereported.
简介:ItisprovedthatalinearlyrecursivesequenceofnindiceaoverfieldF(n≥1)isautorntaticallyaproductofnlioearlyrecurplvesequenceaof1-lndexoverFbythetheoryofHopfalgebras.Bytheway,thecorrespondencebetweenthesetoflinearlyrecursivesequenoesof1-indexandF[X]^0isgeneralisedtothecaseofn-index.
简介:Inthispaper,wepresentanextensivestudyofthelinearlyforcedisotropicturbulence.Byusinganalyticalmethod,weidentifytwoparametricchoices,ofwhichtheyseemtobenewasfarasourknowledgegoes.WeprovethattheunderlyingnonlineardynamicalsystemforlinearlyforcedisotropicturbulenceisthegeneralcaseofacubicLienardequationwithlineardamping.WealsodiscussaFokker–Planckapproachtothisnewdynamicalsystem,whichisbistableandexhibitstwoasymmetricandasymptoticallystablestationaryprobabilitydensities.
简介:Thispaperinvestigatesthemaximumentropyrestorationofblurredbinaryimage.Inconcerningwiththebinarypropertyofimage,anewmaximumentropyrestorationmethodwithbinaryconstraintisproposed.Thepropertiesofexistenceanduniquenessofsolutionarediscussed.Theproblemofmaximumofentropywithtwoconstraintsissolvedandthecorre-spondingalgorithmisgiven.Inthispaper,themaximumboundedentropyprincipleisemployedconcerningthepriorknowledgeofbinaryimage,andthemaximumboundedentropyrestora-tionmethodwithbinaryconstraintisputforward.Theproposesmethods,Wienerfilter(WF)restorationmethodandmaximumentropyrestorationmethodarecompared.Theexperimen-talresultsshowthatthemaximumentropyrestorationmethodandmaximumboundedentropyrestorationmethodwithbinaryconstraintcanimprovethequalityofrestoredimage.
简介:Bymeansofreasonableassumptionandmathematicalderivation,atheoreticexpressionofflowrateforasinglefracturewithlinearlyvaryingwidthwasobtained.Themathematicalderivationwasbasedonthecubiclawandthenewtheoreticexpressionwasanextentionoftraditionalparallelplatemodel.Thisstudymayhelptoanalyzeseepageinfracturedrockmass.
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简介:Nonlinearstochasticoptimalcontrolproblemsarefundamentalincontroltheory.Ageneralclassofsuchproblemscanbereducedtocomputingtheprincipaleigenfunctionofalinearoperator.Here,wedescribeanewmethodforfindingthiseigenfunctionusingamovingleast-squaresfunctionapproximation.Weuseefficientiterativesolversthatdonotrequirematrixfactorization,therebyallowingustohandlelargenumbersofbasisfunctions.Thebasesareevaluatedatcollocationstatesthatchangeoveriterati...
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简介:Inthispaper,weproposeandexperimentallyinvestigatealinearlypolarizednarrow-linewidthrandomfiberlaser(RFL)operatingat1080nmandboosttheoutputpowertokilowattlevelwithnear-diffraction-limitedbeamqualityusingamasteroscillationpoweramplifier.TheRFLbasedonahalf-openedcavity,whichiscomposedofalinearlypolarizednarrow-linewidthfiberBragggratinganda500mpieceofpolarization-maintainedGe-dopedfiber,generatesa0.71Wseedlaserwithan88pmfullwidthathalf-maximum(FWHM)linewidthanda22.5dBpolarizationextinctionratio(PER)forpowerscaling.Atwo-stagefiberamplifierenhancestheseedlasertothemaximal1.01kWwithaPERvalueof17dBandabeamqualityofM_x~2=1.15andM_y~2=1.13.NostimulatedBrillouinscatteringeffectisobservedattheultimatepowerlevel,andtheFWHMlinewidthoftheamplifiedrandomlaserbroadenslinearlyasafunctionoftheoutputpowerwithacoefficientofabout0.1237pm∕W.Tothebestofourknowledge,thisisthefirstdemonstrationofalinearlypolarizednarrow-linewidthRFLwithevenkilowatt-levelnear-diffraction-limitedoutput,andfurtherperformancescalingisongoing.
简介:Wereportonthehigh-poweramplificationofa1064nmlinearlypolarizedlaserinanall-fiberpolarizationmaintainedmasteroscillatorpoweramplifier,whichcanoperateatanoutputpowerlevelof1.3kW.Thebeamquality(M~2)wasmeasuredtobe<1.2atfullpoweroperation.Thepolarizationextinctionrateofthefiberamplifierwasmeasuredtobeabove94%beforemodeinstabilities(MIs)setin,whichreducedtoabout90%aftertheonsetofMI.ThepowerscalingcapabilityofstrategiesforsuppressingMIisanalyzedbasedonasemianalyticalmodel,thetheoreticalresultsofwhichagreewiththeexperimentalresults.ItshowsthatmitigatingMIbycoilingthegainfiberisaneffectiveandpracticalmethodinstandarddouble-claddinglargemodeareafiber,and,bytightcoilingofthegainfibertotheradiusof5.5cm,theMIthresholdcanbeincreasedtothreetimeshigherthanthatwithoutcoilingorloosecoiling.Experimentalstudieshavebeencarriedouttoverifytheidea,whichhasprovedthatMIwassuppressedsuccessfullyintheamplifierbypropercoiling.
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