Dynamical systems in theoretical perspective łódź poland december 11 14 2017 jan awrejcewicz - The f

Page 1


Visit to download the full and correct content document: https://textbookfull.com/product/dynamical-systems-in-theoretical-perspective-lodz-pol and-december-11-14-2017-jan-awrejcewicz/

More products digital (pdf, epub, mobi) instant download maybe you interests ...

Multi Agent Systems and Agreement Technologies 15th

European Conference EUMAS 2017 and 5th International Conference AT 2017 Evry France December 14 15 2017 Revised Selected Papers Francesco Belardinelli

https://textbookfull.com/product/multi-agent-systems-andagreement-technologies-15th-european-conferenceeumas-2017-and-5th-international-conference-at-2017-evry-francedecember-14-15-2017-revised-selected-papers-francesco-belardinel/

Theoretical Computer Science 35th National Conference

NCTCS 2017 Wuhan China October 14 15 2017 Proceedings 1st Edition Dingzhu Du

https://textbookfull.com/product/theoretical-computerscience-35th-national-conference-nctcs-2017-wuhan-chinaoctober-14-15-2017-proceedings-1st-edition-dingzhu-du/

Advances in Computer Entertainment Technology 14th

International Conference ACE 2017 London UK December 14 16 2017 Proceedings 1st Edition Adrian David Cheok

https://textbookfull.com/product/advances-in-computerentertainment-technology-14th-international-conferenceace-2017-london-uk-december-14-16-2017-proceedings-1st-editionadrian-david-cheok/

Dynamical Systems in Population Biology Xiao-Qiang Zhao

https://textbookfull.com/product/dynamical-systems-in-populationbiology-xiao-qiang-zhao/

Dynamical systems in population biology Second Edition

Zhao

https://textbookfull.com/product/dynamical-systems-in-populationbiology-second-edition-zhao/

Differential Equations and Dynamical Systems 2 USUZCAMP

Urgench Uzbekistan August 8 12 2017 Abdulla Azamov

https://textbookfull.com/product/differential-equations-anddynamical-systems-2-usuzcamp-urgench-uzbekistanaugust-8-12-2017-abdulla-azamov/

Intelligent Human Computer Interaction 9th

International Conference IHCI 2017 Evry France December 11 13 2017 Proceedings 1st Edition Patrick Horain

https://textbookfull.com/product/intelligent-human-computerinteraction-9th-international-conference-ihci-2017-evry-francedecember-11-13-2017-proceedings-1st-edition-patrick-horain/

Collaborative Computing Networking Applications and Worksharing 13th International Conference CollaborateCom 2017 Edinburgh UK December 11 13 2017

Proceedings Imed Romdhani

https://textbookfull.com/product/collaborative-computingnetworking-applications-and-worksharing-13th-internationalconference-collaboratecom-2017-edinburgh-ukdecember-11-13-2017-proceedings-imed-romdhani/

Computational Intelligence Cyber Security and Computational Models Models and Techniques for Intelligent Systems and Automation Third International Conference ICC3 2017 Coimbatore India December 14 16

2017 Proceedings Geetha Ganapathi https://textbookfull.com/product/computational-intelligencecyber-security-and-computational-models-models-and-techniquesfor-intelligent-systems-and-automation-third-internationalconference-icc3-2017-coimbatore-india-december-14-16/

Dynamical Systems in Theoretical Perspective

Łódź, Poland December 11–14, 2017

SpringerProceedingsinMathematics&Statistics

Thisbookseriesfeaturesvolumescomposedofselectedcontributionsfrom workshopsandconferencesinallareasofcurrentresearchinmathematicsand statistics,includingoperationresearchandoptimization.Inadditiontoanoverall evaluationoftheinterest,scientificquality,andtimelinessofeachproposalatthe handsofthepublisher,individualcontributionsareallrefereedtothehighquality standardsofleadingjournalsinthe field.Thus,thisseriesprovidestheresearch communitywithwell-edited,authoritativereportsondevelopmentsinthemost excitingareasofmathematicalandstatisticalresearchtoday.

Moreinformationaboutthisseriesathttp://www.springer.com/series/10533

DynamicalSystems

inTheoreticalPerspective

Łódź,PolandDecember11–14,2017

DepartmentofAutomation, BiomechanicsandMechatronics

Łódź UniversityofTechnology

Łódź,Poland

ISSN2194-1009ISSN2194-1017(electronic)

SpringerProceedingsinMathematics&Statistics

ISBN978-3-319-96597-0ISBN978-3-319-96598-7(eBook) https://doi.org/10.1007/978-3-319-96598-7

LibraryofCongressControlNumber:2018948717

MathematicsSubjectClassification(2010):28D-XX,34Ccc,37-XX,46L-xx,65-XX,70-XX,74-XX, 76-XX

© SpringerInternationalPublishingAG,partofSpringerNature2018 Thisworkissubjecttocopyright.AllrightsarereservedbythePublisher,whetherthewholeorpart ofthematerialisconcerned,specificallytherightsoftranslation,reprinting,reuseofillustrations, recitation,broadcasting,reproductiononmicrofilmsorinanyotherphysicalway,andtransmission orinformationstorageandretrieval,electronicadaptation,computersoftware,orbysimilarordissimilar methodologynowknownorhereafterdeveloped.

Theuseofgeneraldescriptivenames,registerednames,trademarks,servicemarks,etc.inthis publicationdoesnotimply,evenintheabsenceofaspecificstatement,thatsuchnamesareexemptfrom therelevantprotectivelawsandregulationsandthereforefreeforgeneraluse.

Thepublisher,theauthorsandtheeditorsaresafetoassumethattheadviceandinformationinthis bookarebelievedtobetrueandaccurateatthedateofpublication.Neitherthepublishernorthe authorsortheeditorsgiveawarranty,expressorimplied,withrespecttothematerialcontainedhereinor foranyerrorsoromissionsthatmayhavebeenmade.Thepublisherremainsneutralwithregardto jurisdictionalclaimsinpublishedmapsandinstitutionalaffiliations.

ThisSpringerimprintispublishedbytheregisteredcompanySpringerNatureSwitzerlandAG Theregisteredcompanyaddressis:Gewerbestrasse11,6330Cham,Switzerland

Preface

Thepresentvolumeisdevotedtothe14theditionofacyclicscientificevent theInternationalConference “DynamicalSystems:TheoryandApplications” (DSTA) organisedbytheDepartmentofAutomation,Biomechanicsand MechatronicsoftheLodzUniversityofTechnologyeverytwoyears.DSTAbelongto importanteventsgatheringagreatnumberofresearchersandengineersfromdifferent fieldsofsciencewheremodellingandanalysisofdynamicalsystemsplayanimportant role.Thevolumeisaresultofaselectionoftherepresentative,theory-oriented chapterswrittenbytheparticipantsofthe14theditionoftheDSTAConference.

Thebooknotonlyprovidesthereaderswithanoverviewoftherecentdevelopmentsinthe fieldofdynamicalsystemsbutalsohelps findinganswerstoreaders ’ ownproblemsandaimstoinspirefurtherresearch.

Argáezetal.(Chapter “ComputationalApproachforCompleteLyapunov Functions”)presentedresultsoftheresearchaimedtoimprovethecomplete algorithmforLyapunovfunctioncomputationthatresultedinbetterapproximation tothechain-recurrentsetinthesystem.

InChapter “Non-conservativeInstabilityofCantileveredNanotubeViaCell DiscretizationMethod”,Aucielloetal.employedthecelldiscretizationmethodto analysethedynamicinstabilityofthecantileveredsingle-walledcarbonnanotube withconcentratedmassandsubjectedtoafollowerforceattheend.Application ofthediscretesystemmodelobtainedbyreductionofthenanotubetoasetofrigid barslinkedbyelasticconstraintsallowedtheauthorstotakeintoaccountnon-local effects,addedmassandthedirectionofthefollowerforce.

Bełdowskietal.(Chapter “FractionalCalculusEvaluationofHyaluronicAcid CrosslinkinginaNanoscopicPartofArticularCartilageModelSystem”)studied mechanicsofphysicalcrosslinkingofhyaluronicacidinthepresenceofcommon phospholipidsinthesynovialjointorgansystems.Applyingfractionalcalculus, theyobtainedresultssuggestingsub-diffusioncharacteristicsintheinvestigated system.

Biś andNamieci ńska(Chapter “TopologicalandMeasure-TheoreticalEntropies ofaSolenoid”)appliedthetopologicalandmeasure-theoreticalapproachto dynamicalpropertiesofasolenoidanddiscussedhomogeneousmeasures.

BjörnssonandHafstein(Chapter “LyapunovFunctionsforAlmostSure ExponentialStability”)focusedonprovingMao’stheoremsontheLyapunov functionsforawiderclassoffunctionsaimingtomakethemmuchmoreapplicable.

InChapter “NumericalAnalysisofDynamicStabilityofanIsotropicPlateby ApplyingToolsUsedinDynamics”,Borkowskipresentedtheresultsofananalysis ofanisotropicplateintermsofitsdynamicstability(orinstability).Forthis purpose,heappliedtoolsthatareusuallyusedinthevibrationstheoryofdynamical systems.

ByrtusandDyk(Chapter “RigidJeffcottRotorBifurcationBehaviourUsing DifferentModelsofHydrodynamicBearings”)focusedondynamicsofamodified versionoftheJeffcottrotor.Theyapplieddifferentmodelsofhydrodynamicbearings. Theresearchallowedthemtodetectnon-linearphenomenasuchasbifurcations.

InChapter “TheBurdenoftheCoinfectionofHIVandTBinthePresenceof Multi-drugResistantStrains”,CarvalhoandPintointroducedfractional-order modellingofinfectionwithHIVandmulti-drugresistanttuberculosisstrains.It yieldedbiologicallyreliableresultsforanalysisoftheburdenofthecoinfectionand treatmentforbothdiseases.

InChapter “ValueDistributionandGrowthofSolutionsofCertainPainlevé Equations”,CiechanowiczandFilipukestimatednewresultsforfourchosen Painlevé equationsforvaluedistributionandthegrowththeory,withsuchvaluesas defect,deviationormultiplicityindex.

Basedonthesingularperturbationmethod,Daniketal.(Chapter “NumericalAnalyticalAlgorithmsforNonlinearOptimalControlProblemsonaLargeTime Interval”)obtainedalgorithmsthatcanbeappliedfornumerical-analyticalinvestigationsofthenon-linearcontinuousanddiscreteoptimalcontrolonalarge fi nite timeinterval.

InChapter “TheDynamicBehavioroftheVehicleWheelsUnderImpact Loads FEMandExperimentalResearches”,Demiyanushkoetal.appliedexperimentaland finiteelementmethodsforstudiesofthedynamicbehaviourofthe vehiclewheelssubjectedtotheimpactload.

GoncalvesLuzJunioretal.(Chapter “OptimalControlforRobotManipulators withThree-Degrees-of-Freedom”)focusedonthemodellingandsimulationofoptimal controlofrobotmanipulatorsforaplanarrobotwiththree-degrees-of-freedom.

InChapter “OptimalControlofAutomotiveMultivariableDynamicalSystems” , Jackiewiczdiscussedadaptivesystemsforautomotiveapplicationsbasedonthe directorself-tuningoptimalcontrollerstrategies fixedbymeansofmemetic algorithms.

Jackowska-ZduniakandForyś (Chapter “MathematicalModelofTwoTypesof AtrioventricularNodalReentrantTachycardia:Slow/FastandSlow/Slow”)proposedapplicationofamodelconsistingoftwocoupledvanderPolequationsto describeheart’spathologicalbehaviourinheart’sconductingsystemsuchas slow/fastandslow/slowtypeofatrioventricularnodalreentranttachycardia.

Motionofasmall-scaleDarrieuscounter-rotatingverticalaxiswindturbinewas thesubjectofthestudydescribedbyKliminaetal.inChapter “Two-Frequency AveragingintheProblemofMotionofaCounter-RotatingVerticalAxisWind

Turbine”.Theauthorsfocusedontwo-frequencyaveragingovertwoangular coordinatesofthedesigneddynamicalmodel.

Knapetal.(Chapter “Process-OrientedApproachtotheDesignofCyberPhysicalSystems”)describedasimplewayofprojectingthecyber-physicalsystemsprojects,whichiscomprehensibleforengineersworkingindifferent fields. Theproposedtask-orientedapproachtodesigningCPSdrawsattentiontoidentificationoftheconnectionbetweenresourcesandallowsforidenti ficationofthreats tothecomponents,connectionsbetweenthemortotheworkingsystem.

Adynamicmodelofahypotheticalmissile-artillerysystemmountedona movingobjectwaspresentedbyKorubaetal.inChapter “AnInverseDynamics AnalysisoftheRemoteControlledArtillery-MissileSystemUndertheInfluenceof Disturbances”,takingintoaccountdrivingtorquesfortheazimuth,theelevation angleandtheangularandlineardisplacementsofthesetbaserelativetothegiven stationarycoordinatesystem.

InChapter “ApproximateIdenti ficationofDynamicalSystems”,Kozáneketal. dealtwithanapproximateidenti ficationoflineardynamicalsystemsbytime responseonunknowninitialdisplacement(orvelocity)withthehelpoftheFourier transform.

Makowski(Chapter “AlgorithmforDampingControlinVehicleSuspension EquippedwithMagneto-RheologicalDampers ”)devotedhisstudytothecontrol algorithmsofsemi-activesystemsforsuspensionofavehicleequippedwithcontrolledmagneto-rheologicaldampers.

InChapter “Shadowing,EntropyandMinimalSets”,Oprochadescribedconsequencesoftheshadowingpropertyforglobalandlocalaspectsofdynamics, takingintoaccount,forinstance,approximationofinvariantmeasuresbyergodic measures.

Ozga(Chapter “AnalysisofVibrationsofanOscillatorUsingStatisticalSeries”) appliedthestatisticalseriesmethodtosolveproblemsofdeterminationofan approximatedistributionofthestrengthofstochasticimpulsesforcingvibrationsof anoscillatorwithdampinginsystemssubjectedtorandomseriesofimpulses.

PawlakandKorczak-Kubiak(Chapter “OnLocalAspectsofEntropy”)introducedthenotionofafullentropypointandanunbalancedpoint.Also,theyused graphicalapproximationbyfunctionshavingeitherthefullentropypointorthe unbalancedpoint.

InChapter “OptimalControlofHybridSystemswithSlidingModes”,Pytlak etal.focusedonthenumericalprocedureforsolvinghybridoptimalcontrol problemswithslidingmodes.Theproposedapproachwascopedwithdifferential–algebraicequationsandguaranteedaccuratetrackingoftheslidingmotionsurface.

Rysaketal.(Chapter “StudyoftheHigh-AmplitudeSolutionsintheSystemof MagneticSlidingOscillatorwithManyDegreesofFreedom ”)investigatedphenomenaofthehigh-amplitudesolutionsinthesystemofmagneticslidingoscillator withmanydegreesoffreedom.

InChapter “TheoreticalInvestigationsontheBehaviorofArti ficialSensorsfor SurfaceTextureDetection”,Scharffetal.analysedtheinfluenceofdifferent magnitudesofvelocitiesandfrictioncoefficientsontheproposedquasi-staticmodel oftheartificialtactilesensor.

Sumietal.(Chapter “DynamicAnalysisofaCompliantTensegrityStructurefor theUseinaGripperApplication”)focusedoninvestigationsofthedynamic behaviourofaplanartensegritystructurewithmultiplestaticequilibriumconfigurationswithrespecttoitsfurtheruseinatwo- finger-gripperapplication.

Astudyofasynchronisationphenomenonasobservedinarotatingstructure consistingofthreecompositebeamsandahubwasdescribedbySzmitetal.in Chapter “SynchronisationAnalysisofaDe-tunedThree-BladedRotor” .

SzulimandRadkowski(Chapter “TheAnalyticalApproachforIdentificationof MagneticallyInducedVibrationsofWorkinginFaultyStateBLDCMotor”)presentedacomparisonofnumericalandexperimentalresultsforidenti ficationof magneticallyinducedvibrationsofaBLDCmotorworkinginafaultystate.

InChapter “Micro-DynamicsofThinTolerance-PeriodicCylindricalShells” , TomczykandSzczerbafocusedonthinlinearlyelasticKirchhoff–Love-typeopen circularcylindricalshellsofafunctionallygradedmacrostructureandonthe tolerance-periodicmicrostructureincircumferentialdirection.

BielskiandWojnar(Chapter “StokesFlowThroughaTubewithWavyWall”) investigatedthepropagationoflonggravitywavespastanincompressible fluidina channelandinatankwithanunevenbottombymeansofanasymptotic homogenisationtheory.

InChapter “ImplementationoftheAdaptiveControlAlgorithmfortheKUKA LWR4+Robot”,WolińskiinvestigatedadynamicalmodeloftheadaptivecontrollerfortheKUKAlightweightredundantroboticmanipulatorrobot.

InChapter “VibrationsofaMulti-spanBeamSubjectedtoaMovingStochastic Load”,Zakęś and Śniadypresentedastudyofthedynamicbehaviourofa multi-spanuniformcontinuousbeamexcitedbyamovingstochasticload.

IgreatlyappreciatethehelpoftheSpringerEditor,ElizabethLeow,inpublishingthechaptersrecommendedbytheScienti ficCommitteeoftheDSTA2017 Conferenceafterastandardpeerreviewprocedure.Also,Iwouldliketoexpressmy gratitudetoreviewersfortheirvoluntaryhelpandsupport.

Łódź,PolandJanAwrejcewicz June2018

ComputationalApproachforCompleteLyapunovFunctions 1 CarlosArgáez,PeterGieslandSigurdurFreyrHafstein

Non-conservativeInstabilityofCantileveredNanotubeViaCell DiscretizationMethod 13

NicolaMariaAuciello,MariaAnnaDeRosa,MariaLippiello andStefaniaTomasiello

FractionalCalculusEvaluationofHyaluronicAcidCrosslinking inaNanoscopicPartofArticularCartilageModelSystem ........... 25 PiotrBełdowski,PiotrWeber,TristanDeLeon,WayneK.AugeII andAdamGadomski

TopologicalandMeasure-TheoreticalEntropiesofaSolenoid ........ 37 AndrzejBiś andAgnieszkaNamieci ńska LyapunovFunctionsforAlmostSureExponentialStability 51 HjorturBjörnssonandSigurdurFreyrHafstein

NumericalAnalysisofDynamicStabilityofanIsotropicPlate byApplyingToolsUsedinDynamics 63 LukaszBorkowski

RigidJeffcottRotorBifurcationBehaviourUsingDifferentModels ofHydrodynamicBearings .................................... 75 MiroslavByrtusand ŠtěpánDyk

TheBurdenoftheCoinfectionofHIVandTBinthePresence ofMulti-drugResistantStrains ................................ 87

AnaCarvalhoandCarlaM.A.Pinto

ValueDistributionandGrowthofSolutionsofCertainPainlevé Equations 99

EwaCiechanowiczandGalinaFilipuk

Numerical-AnalyticalAlgorithmsforNonlinearOptimalControl ProblemsonaLargeTimeInterval 113

YuliaDanik,MikhailDmitriev,DmitryMakarovandTatianaZarodnyuk

TheDynamicBehavioroftheVehicleWheelsUnderImpact Loads FEMandExperimentalResearches ...................... 125 IrinaDemiyanushko,AleksandrVakhromeev,EvgenyLoginov andViolettaMironova

OptimalControlforRobotManipulatorswith Three-Degress-of-Freedom .................................... 135

JoseAdenilsonGonalvesLuzJunior,AngeloMarceloTusset, FredericConradJanzen,RodrigoTumolinRocha,JoseManoelBalthazar andAirtonNabarrete

OptimalControlofAutomotiveMultivariableDynamicalSystems 151 JacekJackiewicz

MathematicalModelofTwoTypesofAtrioventricularNodal ReentrantTachycardia:Slow/FastandSlow/Slow 169 BeataJackowska-ZduniakandUrszulaForyś

Two-FrequencyAveragingintheProblemofMotion ofaCounter-RotatingVerticalAxisWindTurbine ................ 183 LiubovKlimina,EkaterinaShalimova,MaratDosaev,BorisLokshin andVitalySamsonov

Process-OrientedApproachtotheDesignofCyber-Physical Systems ...................................................

LechKnap,JędrzejMączakandMichał Trojgo

AnInverseDynamicsAnalysisoftheRemoteControlled Artillery-MissileSystemUndertheInfluenceofDisturbances 205 ZbigniewKoruba,DanielGapińskiandPiotrSzmidt

ApproximateIdenti ficationofDynamicalSystems 217 JanKozánek, ŠtěpánChládek,JaroslavZapomělandLucie Švamberová

AlgorithmforDampingControlinVehicleSuspensionEquipped withMagneto-RheologicalDampers 235 MichalMakowski

Shadowing,EntropyandMinimalSets .......................... 249 PiotrOprocha

AnalysisofVibrationsofanOscillatorUsingStatisticalSeries ........

OzgaAgnieszka

OnLocalAspectsofEntropy ..................................

RyszardJ.PawlakandEwaKorczak-Kubiak

OptimalControlofHybridSystemswithSlidingModes 283 RadosławPytlak,DamianSuskiandTomaszTarnawski

StudyoftheHigh-AmplitudeSolutionsintheSystemofMagnetic SlidingOscillatorwithManyDegreesofFreedom

295 AndrzejRysak,MagdalenaGregorczyk,KonradChwełatiuk andDanielGaska

TheoreticalInvestigationsontheBehaviorofArtifi cialSensors forSurfaceTextureDetection ..................................

MoritzScharff,MaximilianDarnieder,JoachimSteigenberger, JorgeH.AlencastreandCarstenBehn

DynamicAnalysisofaCompliantTensegrityStructurefortheUse inaGripperApplication 323 SusanneSumi,PhilippSchorr,ValterBöhmandKlausZimmermann

SynchronisationAnalysisofaDe-TunedThree-BladedRotor

Zofi aSzmit,JerzyWarmińskiandJarosławLatalski

TheAnalyticalApproachforIdenti ficationofMagneticallyInduced VibrationsofWorkinginFaultyStateBLDCMotor

PrzemysławSzulimandStanisławRadkowski

Micro-dynamicsofThinTolerance-PeriodicCylindricalShells .......

BarbaraTomczykandPaweł Szczerba

WłodzimierzBielskiandRyszardWojnar

ImplementationoftheAdaptiveControlAlgorithmfortheKUKA LWR4+Robot

ŁukaszWoliński

VibrationsofaMulti-spanBeamSubjectedtoaMovingStochastic Load

FilipZakęś andPawełŚniady

ComputationalApproachforComplete LyapunovFunctions

Abstract Ordinarydifferentialequationsariseinavarietyofapplications,includingclimatemodeling,electronics,predator-preymodeling,etc.,andtheycanexhibit highlycomplicateddynamicalbehaviour.CompleteLyapunovfunctionscapturethis behaviourbydividingthephasespaceintotwodisjointsets:thechain-recurrentpart andthetransientpart.IfacompleteLyapunovfunctionisknownforadynamical systemthequalitativebehaviourofthesystem’ssolutionsistransparenttoalarge degree.ThecomputationofacompleteLyapunovfunctionforagivensystemis,however,averyhardtask.Wepresentsignificantimprovementsofanalgorithmrecently suggestedbytheauthorstocomputecompleteLyapunovfunctions.Previouslythis methodologywasincapabletofullydetectchain-recurrentsetsindynamicalsystems withhighdifferencesinspeed.Inthenewapproachwereplacethesystemunderconsiderationwithanotheronehavingthesamesolutiontrajectoriesbutsuchthatthey aretraversedatamoreuniformspeed.Thequalitativepropertiesofthenewsystem suchasattractorsandrepellersarethesameasfortheoriginalone.Thisapproach givesabetterapproximationtothechain-recurrentsetofthesystemunderstudy.

Keywords CompleteLyapunovFunction · DynamicalSystems Lyapunovtheory · Meshlesscollocation · RadialBasisFunctions

C.Argáez(B) S.F.Hafstein ScienceInstitute,UniversityofIceland,Dunhagi5,107, Reykjavík,Iceland e-mail:carlos@hi.is

S.F.Hafstein e-mail:shafstein@hi.is

P.Giesl

DepartmentofMathematics,UniversityofSussex, FalmerBN19QH,UK

e-mail:P.A.Giesl@sussex.ac.uk

©SpringerInternationalPublishingAG,partofSpringerNature2018 J.Awrejcewicz(ed.), DynamicalSystemsinTheoreticalPerspective, SpringerProceedingsinMathematics&Statistics248, https://doi.org/10.1007/978-3-319-96598-7_1

1Introduction

Letusconsiderageneralautonomousordinarydifferentialequation(ODE) ˙ x = f (x ), where x ∈ Rn .A(classical)Lyapunovfunction[1]isascalar-valuedfunctiondefined inaneighborhoodofaninvariantset.Itisbuilttoshowthestabilityofsuchasetand canbeusedtoanalyseitsbasinofattraction.Hence,itislinkedtooneattractor,e.g. anequilibriumoraperiodicorbit.Inparticular,a(strict)Lyapunovfunctionattains itsminimumontheattractorandisstrictlydecreasingalongsolutionsoftheODE. ThisideaisgeneralizedtoacompleteLyapunovfunction[2–5],whichcompletely characterizesthebehaviourofthedynamicalsysteminthewholephasespace.

AcompleteLyapunovfunctionisascalar-valuedfunction V : Rn → R which isdefinednotonlyonaneighbourhoodofoneattractorbutinthewholephase spaceundertheconditionofbeingnon-increasingalongsolutionsoftheODE.

ThephasespacecanbedividedintotheareawherethecompleteLyapunovfunctionstrictlydecreasesalongsolutiontrajectoriesandtheareawhereitisconstant alongsolutiontrajectories.IfthecompleteLyapunovfunctionissufficientlysmooth, thesepropertiescanbeexpressedbytheorbitalderivative V (x ) =∇ V (x ) f (x ),i.e. thederivativealongsolutionsoftheODE.Thefirstarea,where V (x )< 0,characterizestheregionwheresolutionspassthroughandthelargerthisareais,themore informationisobtainedfromthecompleteLyapunovfunction.Thesecondarea, where V (x ) = 0,includesthechain-recurrentset;thecompleteLyapunovfunction isconstantoneachtransitivecomponentofthechain-recurrentset.Inshort,the firstonedetermineswheresolutionspassthroughwhilethesecondaccountsfor determiningthelong-timebehaviour.

Dynamicalsystemsmodelreal-worldsystemsanddescribetheiroftencomplicatedbehaviour,e.g.thedouble[6]andtriplependulumwithperiodicforcing[7]and dryfriction[8],leadingtotime-periodicandnon-smoothsystems,orthedynamics ofthewobblestone[9].Therearemanymethodstoanalysethequalitativebehaviour ofagivendynamicalsystems:oneofthemdirectlysimulatessolutionswithmany differentinitialconditions.Thisbecomesveryexpensiveandunabletoprovidegeneralinformationonthebehaviourofagivensystem,unlessestimatesareavailable, e.g.whenshadowingsolutions.Moresophisticatedmethodsincludeinvariantmanifoldsandtheircomputation,whichformboundariesofbasinsofattractionforthe attractors[10].Thecellmappingapproach[11]orsetorientedmethods[12]divide thephasespaceintocellsandcomputethedynamicsbetweenthem,seee.g.[13]. TheseideashavebeenusedforacomputationalapproachtoconstructcompleteLyapunovfunctions[14],wheretheauthorsconsiderthediscretesystemgivenbythe time-T map,dividethephasespaceintocellsandcomputethedynamicsbetween themthroughaninducedmultivaluedmap.ThisisdonewiththecomputerpackageGAIO[15].Then,usinggraphsalgorithms,anapproximatecompleteLyapunov functioniscomputed[16].However,evenforlowdimensions,ahighnumberof

cellsisrequiredtocomputetheLyapunovfunctionunderthisapproach.Wewilluse adifferentmethodology,significantlyimprovingthemethoddescribedin[17].

OurnewapproachfollowsfromamethodtocomputeclassicalLyapunovfunctions foragivenequilibriumbyapproximatingthesolutionto V (x ) =−1,i.e.theorbital derivative.Weapproximatethesolutionofthispartialdifferentialequation(PDE) bymeansofmesh-freecollocationwithRadialBasisFunctions:overafinitesetof collocationpoints X ,wecomputeanapproximation v to V thatsolvesthePDEin allcollocationpoints.

Atpointsofthechain-recurrentset,suchasanequilibriumorperiodicorbit, thePDEdoesnothaveasolution;thenumericalmethod,however,alwayshasone. Theideaistousethearea F ,wheretheapproximationispoor,toapproximatethe chain-recurrentset.FollowingthefactthatacompleteLyapunovfunctionshouldbe constantinthechain-recurrentset,inthenextstep,wesolvethePDE V (x ) = 0for x ∈ F and V (x ) =−1elsewhere.

Forthenumericalmethodwethussplitthecollocationpoints X intoaset X 0 = X ∩ F ,wheretheapproximationispoor,and X = X \ X 0 ,whereitworkscorrectly. ThenwesolvethePDE V (x ) = 0forall x ∈ X 0 and V (x ) =−1forall x ∈ X .

Asaresult,theapproximatedfunction v givesusinformationaboutthesolutionto theODEunderconsideration.Ontheonehand,theset X 0 where v (x ) ≈ 0approximatesthechain-recurrentset,includingequilibria,periodicorbitsandhomoclinic orbits,andontheotherhand,theset X inwhich v (x ) ≈−1approximatesthepart wheretheflowisgradient-like.Informationaboutthestabilityandattractionpropertiesisobtainedthroughthelevelsetsofthefunction v :minimaof v correspondto attractorswhilemaximarepresentrepellers.Formoredetailsofthemethodsee[17].

Inthispaperwesignificantlyimprovethemethodfrom[17],describedabove. Firstly,themethodin[17]wasnotabletoaccuratelyidentifythechain-recurrentset inmorecomplicatedexamples,inparticularexampleswherethespeed f (x ) with whichsolutionsoftheODEarepassedthroughvariesconsiderably.Hence,inthis paperwereplacetheoriginalsystem x = f (x ) withthesystem

withparameter δ> 0.

Thenewsystemhasthesamesolutiontrajectoriesastheoriginalsystem,but thesearetraversedatamoreuniformspeed,namely

Thesmaller δ is,thecloserthespeedisto1.

Thismodificationimprovestheabilityofthemethodtofindthechain-recurrent setsignificantly,aswewillshowinthepaper.

Secondly,thefunction V satisfying V (x ) = 0for x ∈ F and V (x ) =−1elsewhereisnotsmoothduetothejumpintheorbitalderivative,whiletheerrorestimates

inmesh-freecollocationrequirethesolutionofthePDEtobesmooth.Toovercome thisproblem,weproposetoreplacethediscontinuousright-handsidefunctionbya smoothfunction.

Letusgiveanoverviewofthepaper:InSect. 2 wepresentthemethodwiththe modifiedsystem(1)andshowtheimprovementsoverthepreviousmethodfrom [17]inthreeexamples.Section 3 studiesthedependenceontheparameter δ .Section 4 discussesreplacingthediscontinuousright-handsidebyasmoothfunction andappliestheimprovedmethodtothesamethreeexamplesbeforeendingwith conclusionsinSect. 5

2NormalizedSpeed

Asdiscussedabove,wefixaparameter δ> 0andconsiderthemodifiedsystem(1) withnormalizedspeed.Wefixafinitesetofcollocationpoints X ,noneofwhich isanequilibriumpointforthesystem.Forourexamplesweusedasubsetofthe hexagonalgrid

3 : k , l ∈ Z

withparameter αHexa-basis > 0.WeapproximatethesolutionofthePDE V (x ) = ∇ V (x ) ˆ f (x ) =−1usingmesh-freecollocationwiththekernel (x ) := ψl ,k (c x ) givenbytheWendlandfunction ψl ,k andparameter c > 0,fordetailssee[17, 18]. Wedenotetheapproximationby v .

Toidentifythecollocationpointswheretheapproximationispoor,indicatingthe chain-recurrentset,weevaluate v (x ) neareachcollocationpoint–notethatinthe collocationpointtheorbitalderivativeis 1byconstruction.Inparticular,in R2 ,for agivencollocationpoint xj ,webuildasetofpoints Yxj placedintwosphereswith center xj ,namely:

Yxj ={xj + r αHexa-basis (cos(θ), sin (θ)) : θ

∪{xj + r 2 αHexa-basis (cos(θ), sin (θ)) : θ

0, 2π/32, 4π/32, 6π/32,..., 2π }} (2)

, 2π/32, 4π/32, 6π/32,..., 2π }} (3)

where r > 0isaparameterand αHexa-basis istheparameterusedtobuildthehexagonal griddefinedabove.Wedefineatoleranceparameter γ> 1andmarkacollocation point xj asbeinginthechain-recurrentset(xj ∈ X 0 )ifthereisatleastonepoint y ∈ Yxj suchthat v (y)>γ . Wewillnowpresentthemethodappliedtothreesystemswithdifferentproperties; thesearethesamesystemsasin[17]sothatwecancomparethetwomethods.

2.1AttractiveandRepellingPeriodicOrbits

Thedynamicalsystemgivenby

hastwoperiodicorbitsandanequilibrium.Theequilibriumattheoriginisasymptoticallystable,andsoistheperiodicorbitwithradius1,whiletheperiodicorbit withradius1/2isunstable.

Weusedahexagonalgridwith αHexa-basis = 0 02intheset [−1 5, 1 5]2 ⊂ R2 whichgivesatotalof29,440collocationpoints,theWendlandfunctionwithparameters (l , k , c ) = (5, 3, 1),thecriticalvalue γ =−0 5,and δ 2 = 10 8 .Furthermore, fortheevaluationgridweset r = 0.5.Wehavecomparedthenewmethod(normalized,right-handside)withthenon-normalizedmethodof[17](left-handside),see Fig. 1.

InthelowerrightfigureinFig. 1,wecanseethattheequilibriumattheoriginis foundwithlesserrorthaninthelowerleftfigurewheretherearemorepointsaround (0, 0).Thechain-recurrentsetactuallylooksverywell-definedinbothcasesbecause oftherelativelysimpledynamics.

Fig.1 Lyapunovfunctionsforsystem(4)underbothnon-normalized(upperleft)andforthe normalizedapproach(upperright).Chain-recurrentsetforbothsystemsnon-normalized(lower left)andnormalized(lowerright)

2.2VanderPolOscillator

System(5)isthetwo-dimensionalformoftheVanderPoloscillator.Thesystemhas anasymptoticallystableperiodicorbitandanunstableequilibriumattheorigin.

Wehaveahexagonalgridwith αHexa-basis = 0.1intheset [−4.0, 4.0]2 ⊂ R2 which givesatotalof7708collocationpoints,theWendlandfunctionwithparameters (l , k , c ) = (4, 2, 1),thecriticalvalue γ =−0.5,and δ 2 = 10 8 .Asbeforeweset r = 0.5intheevaluationgrid.Wehavecomparedthenewmethod(normalized)with thenon-normalizedmethodof[17],seeFig. 2.

Theimprovementoftheproposedmethodcanbeseenclearlyinthelowerfigures inFig. 2:thechain-recurrentsetismuchbetterdetectedinthenormalizedsystem.

Fig.2 Lyapunovfunctionsforsystem(5)underbothnon-normalized(upperleft)andforthe normalizedapproach(upperright).Chain-recurrentsetforbothsystemsnon-normalized(lower left)andnormalized(lowerright)

2.3HomoclinicOrbit

Thesystem(6)hasanasymptoticallystablehomoclinicorbitandanunstableequilibriumattheorigin.

Weusedahexagonalgridwith αHexa-basis = 0.02intheset [−1.5, 1.5]2 ⊂ R2 which givesatotalof29,440collocationpoints,theWendlandfunctionwithparameters (l , k , c ) = (4, 2, 1),thecriticalvalue γ =−0.75,and δ 2 = 10 8 .Againweused r = 0.5intheevaluationgrid.Thenewmethod(normalized)iscomparedwiththe non-normalizedmethodof[17]inFig. 3.

Inthiscase,wecanseeaclearenhancementonthedetectionofthechain-recurrent set.InFig. 3 (lowerleft)thefailingsetover-estimatesthechain-recurrentset,while inFig. 3 (lowerright)thenormalizedmethoddetectsthechain-recurrentsetmuch better.

Summarizing,thenewmethodisabletobetterdetectchain-recurrentsets.

Fig.3 Lyapunovfunctionsforsystem(6)underbothnon-normalized(upperleft)andforthe normalizedapproach(upperright).Chain-recurrentsetforbothsystemsnon-normalized(lower left)andnormalized(lowerright)

3BehaviouroftheLyapunovFunctionsDepending ontheValuesof δ

UsingthesystemdefinedinSect. 2.1 byEq.(4),weshowthedependenceofthe behaviouroftheLyapunovfunctionforanormalizedsystemwithdifferentparameters δ .Wehavechosentoshowexamplesfor δ 2 = 10 10 and δ 2 = 1.Figure 4 shows howtheLyapunovfunctionchangeswithdifferentvaluesof δ 2 :forsmall δ 2 (black) thefunctionhasaderivativecloseto0aroundtheequilibriumpoint,whileforlarge δ 2 (red)thefunctionhasasteepslope.SinceEq.(1)leadstothePDE

∇ V (x ) f (x ) =− δ 2 + f (x ) 2 ,

neartheequilibriumtheright-handsideis ≈−δ .Hence,thegradientof V must becomelargebecause f (x ) issmallclosetotheequilibrium.

Fig.4 Lyapunovfunctionforsystem(4)aroundtheequilibriumpoint.With δ 2 = 1thegradient of V ismuchlargerclosetotheequilibriumatzerothanwith δ 2 = 10 10

4SmoothFunction

OursecondmainobjectiveisinthenextsteptofindaPDEwhichhasasmooth solutionand,subsequently,approximateitssolutionnumerically.

Themethodfrom[17]startswiththePDE V (x ) =−1,whichdoesnothavea solutiononchain-recurrentsets;foranequilibrium x0 ,e.g.weclearlyhave V (x0 ) = 0.Byusingmesh-freecollocationtoapproximateasolutionof V (x ) =−1weobtain anapproximation v whichsatisfies v (x ) ≈−1inareaswhicharenotchain-recurrent andresultsinapoorapproximationinthechain-recurrentset.Letusdenotethearea wheretheapproximationispoorby F

Inthemethoddescribedin[17]wethenstudythePDE

Astheright-handsideisdiscontinuous,thesolution V willnotbeasmoothfunction. Weassumethat F isacompactsetandimprovethemethodbyconsideringthe followingPDEwithsmoothright-handside

where d(x ) = min y∈F x y isthedistancebetweenthepoint x andtheset F and ξ> 0isaparameter.

Toimplementthemethodnumerically,weconstructtheapproximationtothe completeLyapunovfunctionwithournewapproach.Wefirstnormalizeoursystem x = f (x ) byreplacingitwiththesystem(1).Notethatweonlyneedtoevaluatethe right-handside r (x ) atthecollocationpoints.Recallthatweidentifyacollocation point xj tobeinanareaofpoorapproximation F ,asdescribedabove,ifthereexists atleastone y ∈ Yxj with v (y)>γ .Thenwesplitthesetofcollocationpoints X into thesubset X 0 consistingofpointsinanareaofpoorapproximationandtheremaining points X = X \ X 0 .

Forallcollocationpoints xj ∈ X wethenapproximatethedistanceof x totheset F ,representedby X 0 ,by d(xj ) ≈ min y∈X 0 xj y ;

notethat d(xj ) = 0forall xj ∈ X 0 .

Now,theright-handside r (x ) oftheEq.(7)atacollocationpoint xj ∈ X issetto be r (xj ) = 0if xj ∈ X 0 ,and r (xj ) = exp 1 ξ d2 (xj ) if xj ∈ X .

Forourtestsystems(4),(5)and(6)wehavealreadyshownthenormalizedLyapunovfunctionsinFigs. 1, 2 and 3,respectively,sonowweshowthesolutionof

Fig.5 Firstrow:valuesof d asafunctionofthecollocationpointsforsystems(4)incolumn1, (5)incolumn2and(6)incolumn3,respectively.Secondandthirdrow:Lyapunovfunctions(third row)andtheirderivatives(secondrow)forsystems(4)incolumn1,(5)incolumn2and(6)in column3respectively,withthemodified,smoothright-handside

(7)asdescribedaboveinFig. 5.Inthiscase,forallcomputationsinFig. 5,the normalizationfactorusedis δ = 10 8 with ξ = 300.Thesecondrowshowsthatthe orbitalderivativesoftheapproximatedfunctionsaresmoothfunctions.

5Conclusions

InthispaperwehavesignificantlyimprovedamethodtoconstructcompleteLyapunovfunctionsanddeterminethechain-recurrentset.Thetwomainimprovements werefirstlytoconsiderasystemwithnormalizedspeed,whichenabledustodetect thechain-recurrentsetmoreaccurately.Secondly,wehavereplacedthediscontinuousright-handsideofthePDEunderconsiderationbyasmoothfunctionsothatthe PDEhasasmoothsolution,whichiswellapproximatedbytheproposedmethod.

Acknowledgements ThefirstauthorinthispaperissupportedbytheIcelandicResearchFund (Rannís)grantnumber163074-052,CompleteLyapunovfunctions:Efficientnumericalcomputation.SpecialthankstoDr.Jean-ClaudeBerthetforallhisgoodcommentsandadviceonC++.

References

1.Lyapunov,A.M.:Thegeneralproblemofthestabilityofmotion.Int.J.Control 3(55),521–790 (1992)

2.Conley,C.:IsolatedInvariantSetsandtheMorseIndex.In:AmericanMathematicalSociety, CBMSRegionalConferenceSeries,vol.38(1978)

3.Conley,C.:ThegradientstructureofaflowI.ErgodicTheoryDynam.Syst. 8,11–26(1988)

4.Hurley,M.:Chainrecurrence,semiflows,andgradients.J.Dyn.Diff.Equat. 3(7),437–456 (1995)

5.Hurley,M.:Lyapunovfunctionsandattractorsinarbitrarymetricspaces.Proc.Amer.Math. Soc. 126,245–256(1998)

6.Awrejcewicza,J.,Wasilewskia,G.,Kudra,G.,Reshminb,S.:Anexperimentwithswingingup adoublependulumusingfeedbackcontrol.J.Comput.Syst.Sci.Int. 51(2),176–182(2012)

7.Awrejcewicz,J.,Kudra,G.,Wasilewski,G.:Experimentalandnumericalinvestigationof chaoticregionsinthetriplephysicalpendulum.NonlinearDyn 50,755–766(2007)

8.Awrejcewicz,J.,Kudra,G.,Wasilewski,G.:Chaoticzonesintriplependulumdynamicsobservedexperimentallyandnumerically.Appl.Mech.Mater. 9,1–17(2008)

9.Awrejcewicz,J.,Kudra,G.:Mathematicalmodellingandsimulationofthebifurcationalwobblestonedynamics.Discontinuity,Nonlinearity,Complexity 3(2),123–132(2014)

10.Krauskopf,B.,Osinga,H.,Doedel,E.J.,Henderson,M.,Guckenheimer,J.,Vladimirsky,A., Dellnitz,M.,Junge,O.:Asurveyofmethodsforcomputing(un)stablemanifoldsofvector fields.Internat.J.Bifur.ChaosAppl.Sci.Engrg., 3(15),763–791

11.Hsu,C.S.:Cell-to-cellmapping.In:AppliedMathematicalSciences.vol.64.Springer-Verlag, NewYork(1987). https://doi.org/10.1007/978-1-4757-3892-6

12.Dellnitz,M.,Junge,O.:Setorientednumericalmethodsfordynamicalsystems.In:Handbook ofDynamicalSystems,vol.2,pp.221–264.North-Holland,Amsterdam(2002). https://doi. org/10.1016/S1874-575X(02)80026-1

13.Osipenko,G.:Dynamicalsystems,graphs,andalgorithms.In:LectureNotesinMathematics. vol.1889.Springer-Verlag,Berlin(2007)

14.Kalies,W.,Mischaikow,K.,VanderVorst,R.:Analgorithmicapproachtochainrecurrence. Found.Comput.Math. 4,409–449(2005)

15.Dellnitz,M.,Froyland,G.,Junge,O.:ThealgorithmsbehindGAIO-setorientednumericalmethodsfordynamicalsystems.ErgodicTheory.Analysis,andEfficientSimulationof DynamicalSystems,pp.145–174.Springer,Berlin(2001)

16.Ban,H.,Kalies,W.:AcomputationalapproachtoConley’sdecompositiontheorem.J.Comput. NonlinearDynam. 1(4),312–319(2006)

17.Argáez,C.,Giesl,P.,Hafstein,S.:Analysingdynamicalsystems–towardscomputingcomplete lyapunovfunctions.In:Proceedingsofthe7thInternationalConferenceonSimulationand ModelingMethodologies,TechnologiesandApplications–Volume1:SIMULTECH,pp.134–144(2017)

18.Giesl,P.:ConstructionofGlobalLyapunovFunctionsUsingRadialBasisFunctions.In:Lecture NotesinMath.,vol.1904.Springer(2007)

Non-conservativeInstability ofCantileveredNanotubeViaCell DiscretizationMethod

Abstract Basedonthenonloocalelasticitytheory,thispaperdealswiththedynamic instabilityanalysisofcantileveredsingle-walledcarbonnanotubewithconcentrated mass,locatedatagenericposition,andsubjecttoafollowerforceatthefreeend. Accountingforthesmallscaleeffect,thegoverningequationsofmotionarederived usinganalternativeHamilton’svariationalprincipleandthegoverningequations aresolvednumericallyemployingtheCell-DiscretizationMethod(CDM)inwhich thenanotubeisreducedtoasetofrigidbarslinkedtogetherbymeansofelasticconstraints.Theresultingdiscretesystemtakesintoaccountnonlocaleffects, addedmass,andpositionofaddedmass,andfollowerforcedirection.Acomparativeanalysisisperformedinordertoverifytheaccuracyandvalidityoftheproposed numericalmethod.Theeffectsofthenonlocalparameteranddimensionlessmasson thedynamicinstabilityofsingle-walledcarbonnanotubeareshownanddiscussed indetails.Theeffectofasub-tangentialfollowerforceonthestabilityofcantilever single-walledcarbonnanotubeisstudied.Finally,thevalidityoftheproposedanalysisisconfirmedbycomparingthepresentresultswiththoseobtainedfromthe litertaureandlistedinbibliography. Keywords

N.M.Auciello M.A.DeRosa(B)

SchoolofEngineering,UniversityofBasilicata, Vialedell’AteneoLucano10,85100Potenza,Italy

e-mail:maria.derosa@unibas.it

N.M.Auciello

e-mail:nicola.auciello@unibas.it

M.Lippiello

UniversityofNaplesFedericoII,DiSt,ViaFornoVecchio36,80134Naples,Italy e-mail:maria.lippiello@unina.it

S.Tomasiello

UniversityofSalerno,CORISA,84084Fisciano(SA),Italy e-mail:stomasiello@unisa.it

©SpringerInternationalPublishingAG,partofSpringerNature2018 J.Awrejcewicz(ed.), DynamicalSystemsinTheoreticalPerspective, SpringerProceedingsinMathematics&Statistics248, https://doi.org/10.1007/978-3-319-96598-7_2

1Introduction

Outstandingmechanical,physicalandelectronicpropertiesofcarbonnanotubes (CNTs)havestimulatedintensivestudiesinavarietyoffieldsofscienceandengineeringsincetheirfirstdiscoveryin1991thankstoIijima’spaper[1].

TheliteratureregardingthematerialpropertiesandmechanicalbehaviourofCNTs isveryrichandtwomaintheoreticalapproaches,basedonthemoleculardynamics andcontinuummechanics,havebeendeveloped.Althoughtheclassicalcontinuum theoriesareabletopredictthemechanicalbehaviorofnanostructures,itturnedup tobeunsuitable,becausethesmallsizeeffectsareneglected.Thusadoptingthe nonlocalelasticitytheory,asdevelopedbyEringenin[2, 3],isusual.Applyingthe Erigen’stheory,manypapersinvestigatingthemechanicalpropertiesofCNTshave beenappearing.Inparticular,elasticmodelsofbeamshavebeenimplementedto studystaticanddynamicproblems,suchasbending,bucklingandfreevibrationof carbonnanotubes,usingEuler-Bernoulli[4, 5]andTimoshenko[6–8]beammodels.

Inrecentyears,duetotheremarkablepropertiesofCNTs,agrowinginterest,in theanalysisofthevibrationsofnanotubesunderanonconservativefield,suchas afollowerforces,andtheirinfluenceonfree-vibrationofCNTs,hasattractedthe attentionofmanyreseachers,althoughfewpapersregardingthestructuralstability oftheCNTscanbefoundinliterature(see[9–11]).

Thepresentpaperdealswiththenonlocaldynamicinstabilityofacantilevered single-walledcarbonnanotubewithanattachedconcentratedmass,locatedata genericposition,anditspositionofaddedmassandsubjecttoafollowerforce,at thefree-end.Thegoverningequationsofmotionarederivedusinganalternative Hamilton’svariationalprincipleandaresolvednumericallyemployingtheCellDiscretizationMethod(CDM),whichreducesthenanotubetoasetofrigidbars linkedtogetherbymeansofelasticconstraints.Theresultingdiscretesystemtakes intoaccountnonlocaleffects,addedmass,anditsposition,andfollowerforcedirection.Acomparativeanalysisisperformedinordertoverifyaccuracyandvalidityof theproposednumericalmethod.Theeffectsofnonlocalparameteranddimensionless massonthedynamicinstabilityofSWCNTareshownanddiscussedindetails.The effectofasub-tangentialfollowerforceonthestabilityofcantileversingle-walled carbonnanotubeisstudied.

2.1GoverningEquationsofMotionforDynamicInstability

Considerasingle-walledcarbonnanotube(SWCNT),clampedattheleftendand freeattherightone,oflengthL.Thenanotubeissubjecttoasubtangentialforcep,at thefreeend,andcarryingaconcentratedmassMγ ,locatedatagenericposition,as

Fig.1 Geometryofsingle-walledcarbonnanotube(SWCNT)

showninFig. 1.Thedirectionoftheforcepisspecifiedby ψ ,where ψ denotes theanglebetweenthe z -axisandthedirectionofthecompressivesubtangentialforce.

AccordingtotheHamilton’sPrinciple,themotionequationsofthesystemare derivedasfollows:

where δ denotesthevariation, t istime,TandEarethekineticandtotalpotential energyofthenanotube,respectively,whileWnc representsthenonconservativevirtualworkoftheappliedload.

Thekineticenergyofthenanostructureunderconsiderationcanbeexpressedas:

where v (z ) isthetransversedisplacementofthenanotube,with z beingthespatial coordinatealongthenanotube,Aisthecross-sectionalarea, ρ themassdensityof SWCNT,Mγ denotestheconcentratedmass,attheabscissa z = γ L,andJm isrotary inertiaoftheaddedmass.

ThetotalpotentialenergyEt assumesthefollowingform:

i.e.Et issumofthreedifferentcontributions:thestrainenergyLe ofthenanotube,the potentialenergyPoftheinertialforce ρ A ∂ 2 v (z ,t ) ∂ t 2 duetoadditionaldisplacement

(e0 a )2 ∂ 2 v (z ,t ) ∂ z 2 andfinallythepotentialenergyVofaxialcomponentofthefollower

16N.M.Aucielloetal.

forcep.InEq.(3),EisYoung’smodulus,Ithesecondmomentofthecross-sectional areaA, e0 isanonlocalscalingparameter,whichhastobeexperimentallydetermined foreachmaterial,and a isaninternalcharacteristiclength.

Takingintoaccounttheexpressionsofkineticandpotentialenergy,onegets:

Finally,thenonconservativevirtualworkofthesetransversecomponentscanbe expressedas:

Theparameter completelydefinesthedynamicbehaviourofthesystem:for =0 theclassicalconservativeEulercaseisrecovered,whereasfor =1thenanobeam issubjecttopurelytangentialforces(Beckproblem).As variesintherange[0,1] criticalloadsarereachedbymeansofdivergenceorflutterinstability.

SinceobtaininganexactanalyticalsolutiontoEq.(1)isnotthateasy,thepresent studyreliesontheapproximationsolution.Forlinearfreevibrationofananotube, thevibrationmodesareharmonicintime.Hence,thetemporalandspatialtermsfor transversedeformationcanbeseparetedas:

wherev(z ) representsthevibrationamplitudeshapefunction,i= √ 1and ω isthe naturalfrequency.TofindthesolutionoftheEq.(1),theCell-DiscretizationMethod (CDM)isappliedtosolvetheeigenvalueproblem.

2.2MethodofSolution:Cell-DiscretizationMethod(CDM)

TheCellDiscretizationMethod(CDM)isanefficientnumericalmethodforthe solutionoflinearpartialdifferentialequations.Themethodhasalreadybeenusedby theauthors[12, 13]andbyRaithelandFranciosi[14]fordifferentstructuralproblems.Recently,DeRosaandLippiello[15]haveemployedtheCDMtoinvestigate thefreevibrationfrequenciesproblemofcoaxialdouble-walledcarbonnanotubes (DWCNTs)andin[16]foranalyzingthefreevibrationanalysisofsingle-walled

Fig.2 Structuralsystem discretizationCDmethod

carbonnanotube(SWCNT)boundedattheends,withtranslationalandelasticconstraints,andattachedmass.InthepresentpapertheCDmethodhasbeenproperly modifiedfortheconsideredproblem.Thenanotubeisreducedtoasetof t rigidbars, linkedtogetherby t + 1elasticcells,wheremassesandstiffnessesaresupposedto beconcentrated,(seeFig. 2).Inthisway,thestructureisreducedtoasystemwith finitenumberofdegreesoffreedom(MDOF).TheLagragianparameterscanbe assumedtobethe ϕi rotationsoftherigidbars,i.e.thegeneralizedcoordinatesofthe rigid-elasticsystem.Allthepossibleconfigurationsarefunctionsofthefollowing vector:

andtheverticalcomponentsofthenodaldisplacementsandtherelativerotations betweenthetwofacesoftheelasticcellsaregivenbythefollowingexpressions:

Inmatrixform,beingA A AthedisplacementsmatrixandB B Btherotationsmatrix,itis possibletowrite:

, , ,ψ

TherectangularmatricesA A AandB B Bhavet+1rowsandtcolumns,andeachentrycan becalculatedaccordingtoFig. 2.TheformofmatrixA A Ais:

with A1j =0,forj=1,…,t;whilethematrixB B Bhas Bii =1and B(i +1)i =−1,for i = 1,..., t 1.Accordingtothepresentdiscretization,theaxialcomponentsof thenodaldisplacementsassumethefollowingform:

Inthematrixform,theaxialdisplacementsofcellt+1becomes:

whereDlDlDl isdiagonalmatrixoftheterms L t .

SubstitutingtheEqs.(8–9)and(12–13)intoEq.(4),thekineticenergyshouldbe expressedasfunctionsoftheLagrangiancoordinatesasfollows:

or,indiscretizedform:

Themassisconcentratedattheelasticcellsanditisrepresentedbythefollowing termsofthediagonalmatrix:

andtheEq.(15)becomes:

Another random document with no related content on Scribd:

“The best thing in the world for you, mamma,” said Dick, “and jolly for us, once in a way, to have you all to ourselves.”

What could mortal woman, being the boys’ mother, say more? I am afraid she would have considered favourably the idea of going to Nova Zembla, wherever that may be, under such conditions. And Winks, though he yawned as he listened, thought well of it too; he liked driving, on the whole, though too much of it bored him, and he had not at all approved when his mistress “put down” her carriage. They set off next morning in the brightness of noon, through the country which had not yet lost any of its beauty, though here and there the trees had yellow patches on them, and the parks were all burnt brown with the heat of summer. They were a very merry party, notwithstanding that the final examination was hanging over Dick’s head, and the parting which must follow. Winks, for his part, after two or three hours of it, got bored with the levity of the conversation, and rustled about so, that he was put out of the carriage to run for the good of his health. He went along for a mile or two, pleased enough, gathering dust in clouds about him. But when he intimated a desire to be taken in, the boys, hard-hearted beings, laughed in the face of Winks.

“A run will do you good, old fellow,” said Dick, with cruel satisfaction. A short time afterwards, I am sorry to say, a dreadful accident, nature unknown, happened to Winks. He uttered a heart-rending shriek, and appeared immediately after making his way towards the carriage, holding up one feathery paw in demonstrative suffering. The anxious party stopped immediately, and Winks made his way to them, laboriously limping and uttering plaintive cries. But when, all a-dust as he was, this hypocrite was lifted into the carriage, holding up the injured member—and was softly laid upon the softest cushion to have it examined, words fail me to express the sardonic grin with which he showed his milk-white teeth. There was no more the matter with the little villain’s paw, my gentle reader, than with yours or mine.

Never was there a pleasanter two days’ journey than this which Mrs. Eastwood made with her boys through the sunshiny autumn country, along the road, where gold-coloured leaves dropped in her lap as they drove her along, now one on the box, now another, in their turn; till the High Lodge at last appeared in sight all covered with white downy clusters of clematis done flowering, with late roses, and matted network of interlacing leaves.

Innocent rushed to the door, slim and pale in her black dress, her eyes shining with sudden delight, her soft face inspired.

“You have come to take me home. I am Nelly now!” she cried, throwing her arms about the common mother. Jenny, whom she had not noticed, leant back upon the carriage, looking at her with eyes that glowed under his dark brows. He had always stood by Innocent since the day when he had read Greek to her in the Lady’s Walk; he had always been sure that “something would come of her.” “We don’t know half what Innocent will come to!” he repeated now to himself.

GILBERT AND RIVINGTON, PRINTERS, ST. JOHN’S SQUARE, LONDON.

END OF THE PROJECT GUTENBERG EBOOK INNOCENT

***

Updated editions will replace the previous one—the old editions will be renamed.

Creating the works from print editions not protected by U.S. copyright law means that no one owns a United States copyright in these works, so the Foundation (and you!) can copy and distribute it in the United States without permission and without paying copyright royalties. Special rules, set forth in the General Terms of Use part of this license, apply to copying and distributing Project Gutenberg™ electronic works to protect the PROJECT GUTENBERG™ concept and trademark. Project Gutenberg is a registered trademark, and may not be used if you charge for an eBook, except by following the terms of the trademark license, including paying royalties for use of the Project Gutenberg trademark. If you do not charge anything for copies of this eBook, complying with the trademark license is very easy. You may use this eBook for nearly any purpose such as creation of derivative works, reports, performances and research. Project Gutenberg eBooks may be modified and printed and given away—you may do practically ANYTHING in the United States with eBooks not protected by U.S. copyright law. Redistribution is subject to the trademark license, especially commercial redistribution.

START: FULL LICENSE

THE FULL PROJECT GUTENBERG LICENSE

PLEASE READ THIS BEFORE YOU DISTRIBUTE OR USE THIS WORK

To protect the Project Gutenberg™ mission of promoting the free distribution of electronic works, by using or distributing this work (or any other work associated in any way with the phrase “Project Gutenberg”), you agree to comply with all the terms of the Full Project Gutenberg™ License available with this file or online at www.gutenberg.org/license.

Section 1. General Terms of Use and Redistributing Project Gutenberg™ electronic works

1.A. By reading or using any part of this Project Gutenberg™ electronic work, you indicate that you have read, understand, agree to and accept all the terms of this license and intellectual property (trademark/copyright) agreement. If you do not agree to abide by all the terms of this agreement, you must cease using and return or destroy all copies of Project Gutenberg™ electronic works in your possession. If you paid a fee for obtaining a copy of or access to a Project Gutenberg™ electronic work and you do not agree to be bound by the terms of this agreement, you may obtain a refund from the person or entity to whom you paid the fee as set forth in paragraph 1.E.8.

1.B. “Project Gutenberg” is a registered trademark. It may only be used on or associated in any way with an electronic work by people who agree to be bound by the terms of this agreement. There are a few things that you can do with most Project Gutenberg™ electronic works even without complying with the full terms of this agreement. See paragraph 1.C below. There are a lot of things you can do with Project Gutenberg™ electronic works if you follow the terms of this agreement and help preserve free future access to Project Gutenberg™ electronic works. See paragraph 1.E below.

1.C. The Project Gutenberg Literary Archive Foundation (“the Foundation” or PGLAF), owns a compilation copyright in the collection of Project Gutenberg™ electronic works. Nearly all the individual works in the collection are in the public domain in the United States. If an individual work is unprotected by copyright law in the United States and you are located in the United States, we do not claim a right to prevent you from copying, distributing, performing, displaying or creating derivative works based on the work as long as all references to Project Gutenberg are removed. Of course, we hope that you will support the Project Gutenberg™ mission of promoting free access to electronic works by freely sharing Project Gutenberg™ works in compliance with the terms of this agreement for keeping the Project Gutenberg™ name associated with the work. You can easily comply with the terms of this agreement by keeping this work in the same format with its attached full Project Gutenberg™ License when you share it without charge with others.

1.D. The copyright laws of the place where you are located also govern what you can do with this work. Copyright laws in most countries are in a constant state of change. If you are outside the United States, check the laws of your country in addition to the terms of this agreement before downloading, copying, displaying, performing, distributing or creating derivative works based on this work or any other Project Gutenberg™ work. The Foundation makes no representations concerning the copyright status of any work in any country other than the United States.

1.E. Unless you have removed all references to Project Gutenberg:

1.E.1. The following sentence, with active links to, or other immediate access to, the full Project Gutenberg™ License must appear prominently whenever any copy of a Project Gutenberg™ work (any work on which the phrase “Project Gutenberg” appears, or with which the phrase “Project Gutenberg” is associated) is accessed, displayed, performed, viewed, copied or distributed:

This eBook is for the use of anyone anywhere in the United States and most other parts of the world at no cost and with almost no restrictions whatsoever. You may copy it, give it away or re-use it under the terms of the Project Gutenberg License included with this eBook or online at www.gutenberg.org. If you are not located in the United States, you will have to check the laws of the country where you are located before using this eBook.

1.E.2. If an individual Project Gutenberg™ electronic work is derived from texts not protected by U.S. copyright law (does not contain a notice indicating that it is posted with permission of the copyright holder), the work can be copied and distributed to anyone in the United States without paying any fees or charges. If you are redistributing or providing access to a work with the phrase “Project Gutenberg” associated with or appearing on the work, you must comply either with the requirements of paragraphs 1.E.1 through 1.E.7 or obtain permission for the use of the work and the Project Gutenberg™ trademark as set forth in paragraphs 1.E.8 or 1.E.9.

1.E.3. If an individual Project Gutenberg™ electronic work is posted with the permission of the copyright holder, your use and distribution must comply with both paragraphs 1.E.1 through 1.E.7 and any additional terms imposed by the copyright holder. Additional terms will be linked to the Project Gutenberg™ License for all works posted with the permission of the copyright holder found at the beginning of this work.

1.E.4. Do not unlink or detach or remove the full Project Gutenberg™ License terms from this work, or any files containing a part of this work or any other work associated with Project Gutenberg™.

1.E.5. Do not copy, display, perform, distribute or redistribute this electronic work, or any part of this electronic work, without prominently displaying the sentence set forth in paragraph 1.E.1 with active links or immediate access to the full terms of the Project Gutenberg™ License.

1.E.6. You may convert to and distribute this work in any binary, compressed, marked up, nonproprietary or proprietary form, including any word processing or hypertext form. However, if you provide access to or distribute copies of a Project Gutenberg™ work in a format other than “Plain Vanilla ASCII” or other format used in the official version posted on the official Project Gutenberg™ website (www.gutenberg.org), you must, at no additional cost, fee or expense to the user, provide a copy, a means of exporting a copy, or a means of obtaining a copy upon request, of the work in its original “Plain Vanilla ASCII” or other form. Any alternate format must include the full Project Gutenberg™ License as specified in paragraph 1.E.1.

1.E.7. Do not charge a fee for access to, viewing, displaying, performing, copying or distributing any Project Gutenberg™ works unless you comply with paragraph 1.E.8 or 1.E.9.

1.E.8. You may charge a reasonable fee for copies of or providing access to or distributing Project Gutenberg™ electronic works provided that:

• You pay a royalty fee of 20% of the gross profits you derive from the use of Project Gutenberg™ works calculated using the method you already use to calculate your applicable taxes. The fee is owed to the owner of the Project Gutenberg™ trademark, but he has agreed to donate royalties under this paragraph to the Project Gutenberg Literary Archive Foundation. Royalty payments must be paid within 60 days following each date on which you prepare (or are legally required to prepare) your periodic tax returns. Royalty payments should be clearly marked as such and sent to the Project Gutenberg Literary Archive Foundation at the address specified in Section 4, “Information about donations to the Project Gutenberg Literary Archive Foundation.”

• You provide a full refund of any money paid by a user who notifies you in writing (or by e-mail) within 30 days of receipt that s/he does not agree to the terms of the full Project Gutenberg™ License. You must require such a user to return or destroy all

copies of the works possessed in a physical medium and discontinue all use of and all access to other copies of Project Gutenberg™ works.

• You provide, in accordance with paragraph 1.F.3, a full refund of any money paid for a work or a replacement copy, if a defect in the electronic work is discovered and reported to you within 90 days of receipt of the work.

• You comply with all other terms of this agreement for free distribution of Project Gutenberg™ works.

1.E.9. If you wish to charge a fee or distribute a Project Gutenberg™ electronic work or group of works on different terms than are set forth in this agreement, you must obtain permission in writing from the Project Gutenberg Literary Archive Foundation, the manager of the Project Gutenberg™ trademark. Contact the Foundation as set forth in Section 3 below.

1.F.

1.F.1. Project Gutenberg volunteers and employees expend considerable effort to identify, do copyright research on, transcribe and proofread works not protected by U.S. copyright law in creating the Project Gutenberg™ collection. Despite these efforts, Project Gutenberg™ electronic works, and the medium on which they may be stored, may contain “Defects,” such as, but not limited to, incomplete, inaccurate or corrupt data, transcription errors, a copyright or other intellectual property infringement, a defective or damaged disk or other medium, a computer virus, or computer codes that damage or cannot be read by your equipment.

1.F.2. LIMITED WARRANTY, DISCLAIMER OF DAMAGES - Except for the “Right of Replacement or Refund” described in paragraph 1.F.3, the Project Gutenberg Literary Archive Foundation, the owner of the Project Gutenberg™ trademark, and any other party distributing a Project Gutenberg™ electronic work under this agreement, disclaim all liability to you for damages, costs and

expenses, including legal fees. YOU AGREE THAT YOU HAVE NO REMEDIES FOR NEGLIGENCE, STRICT LIABILITY, BREACH OF WARRANTY OR BREACH OF CONTRACT EXCEPT THOSE PROVIDED IN PARAGRAPH 1.F.3. YOU AGREE THAT THE FOUNDATION, THE TRADEMARK OWNER, AND ANY DISTRIBUTOR UNDER THIS AGREEMENT WILL NOT BE LIABLE TO YOU FOR ACTUAL, DIRECT, INDIRECT, CONSEQUENTIAL, PUNITIVE OR INCIDENTAL DAMAGES EVEN IF YOU GIVE NOTICE OF THE POSSIBILITY OF SUCH DAMAGE.

1.F.3. LIMITED RIGHT OF REPLACEMENT OR REFUND - If you discover a defect in this electronic work within 90 days of receiving it, you can receive a refund of the money (if any) you paid for it by sending a written explanation to the person you received the work from. If you received the work on a physical medium, you must return the medium with your written explanation. The person or entity that provided you with the defective work may elect to provide a replacement copy in lieu of a refund. If you received the work electronically, the person or entity providing it to you may choose to give you a second opportunity to receive the work electronically in lieu of a refund. If the second copy is also defective, you may demand a refund in writing without further opportunities to fix the problem.

1.F.4. Except for the limited right of replacement or refund set forth in paragraph 1.F.3, this work is provided to you ‘AS-IS’, WITH NO OTHER WARRANTIES OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO WARRANTIES OF MERCHANTABILITY OR FITNESS FOR ANY PURPOSE.

1.F.5. Some states do not allow disclaimers of certain implied warranties or the exclusion or limitation of certain types of damages. If any disclaimer or limitation set forth in this agreement violates the law of the state applicable to this agreement, the agreement shall be interpreted to make the maximum disclaimer or limitation permitted by the applicable state law. The invalidity or unenforceability of any provision of this agreement shall not void the remaining provisions.

1.F.6. INDEMNITY - You agree to indemnify and hold the Foundation, the trademark owner, any agent or employee of the Foundation, anyone providing copies of Project Gutenberg™ electronic works in accordance with this agreement, and any volunteers associated with the production, promotion and distribution of Project Gutenberg™ electronic works, harmless from all liability, costs and expenses, including legal fees, that arise directly or indirectly from any of the following which you do or cause to occur: (a) distribution of this or any Project Gutenberg™ work, (b) alteration, modification, or additions or deletions to any Project Gutenberg™ work, and (c) any Defect you cause.

Section 2. Information about the Mission of Project Gutenberg™

Project Gutenberg™ is synonymous with the free distribution of electronic works in formats readable by the widest variety of computers including obsolete, old, middle-aged and new computers. It exists because of the efforts of hundreds of volunteers and donations from people in all walks of life.

Volunteers and financial support to provide volunteers with the assistance they need are critical to reaching Project Gutenberg™’s goals and ensuring that the Project Gutenberg™ collection will remain freely available for generations to come. In 2001, the Project Gutenberg Literary Archive Foundation was created to provide a secure and permanent future for Project Gutenberg™ and future generations. To learn more about the Project Gutenberg Literary Archive Foundation and how your efforts and donations can help, see Sections 3 and 4 and the Foundation information page at www.gutenberg.org.

Section 3. Information about the Project Gutenberg Literary Archive Foundation

The Project Gutenberg Literary Archive Foundation is a non-profit 501(c)(3) educational corporation organized under the laws of the state of Mississippi and granted tax exempt status by the Internal Revenue Service. The Foundation’s EIN or federal tax identification number is 64-6221541. Contributions to the Project Gutenberg Literary Archive Foundation are tax deductible to the full extent permitted by U.S. federal laws and your state’s laws.

The Foundation’s business office is located at 809 North 1500 West, Salt Lake City, UT 84116, (801) 596-1887. Email contact links and up to date contact information can be found at the Foundation’s website and official page at www.gutenberg.org/contact

Section 4. Information about Donations to the Project Gutenberg Literary Archive Foundation

Project Gutenberg™ depends upon and cannot survive without widespread public support and donations to carry out its mission of increasing the number of public domain and licensed works that can be freely distributed in machine-readable form accessible by the widest array of equipment including outdated equipment. Many small donations ($1 to $5,000) are particularly important to maintaining tax exempt status with the IRS.

The Foundation is committed to complying with the laws regulating charities and charitable donations in all 50 states of the United States. Compliance requirements are not uniform and it takes a considerable effort, much paperwork and many fees to meet and keep up with these requirements. We do not solicit donations in locations where we have not received written confirmation of compliance. To SEND DONATIONS or determine the status of compliance for any particular state visit www.gutenberg.org/donate.

While we cannot and do not solicit contributions from states where we have not met the solicitation requirements, we know of no

prohibition against accepting unsolicited donations from donors in such states who approach us with offers to donate.

International donations are gratefully accepted, but we cannot make any statements concerning tax treatment of donations received from outside the United States. U.S. laws alone swamp our small staff.

Please check the Project Gutenberg web pages for current donation methods and addresses. Donations are accepted in a number of other ways including checks, online payments and credit card donations. To donate, please visit: www.gutenberg.org/donate.

Section 5. General Information About Project Gutenberg™ electronic works

Professor Michael S. Hart was the originator of the Project Gutenberg™ concept of a library of electronic works that could be freely shared with anyone. For forty years, he produced and distributed Project Gutenberg™ eBooks with only a loose network of volunteer support.

Project Gutenberg™ eBooks are often created from several printed editions, all of which are confirmed as not protected by copyright in the U.S. unless a copyright notice is included. Thus, we do not necessarily keep eBooks in compliance with any particular paper edition.

Most people start at our website which has the main PG search facility: www.gutenberg.org.

This website includes information about Project Gutenberg™, including how to make donations to the Project Gutenberg Literary Archive Foundation, how to help produce our new eBooks, and how to subscribe to our email newsletter to hear about new eBooks.

Turn static files into dynamic content formats.

Create a flipbook
Issuu converts static files into: digital portfolios, online yearbooks, online catalogs, digital photo albums and more. Sign up and create your flipbook.