简介：Purpose:Thepurposeofthisstudywastocompare4techniquesforarrivalatabaseaftersprintingmaximallytoreachit:slidinghead-first,slidingfeet-first,runningthroughthebasewithoutslowing,andstoppingonthebase.Asecondarypurposeofthestudywastodetermineanyadvantagetheremaybetodivingintofirstbasetoarrivesoonerthanrunningthroughthebase.Methods:Twohigh-definitionvideocameraswereusedtocapture3-dimensionalkinematicsofslidingtechniquesof9intercollegiatebaseballplayers.Anothervideocamerawasusedtotimerunsfromfirstbasetosecondin4counterbalancedconditions:runningthroughthebase,slidinghead-first,slidingfeet-first,andrunningtoastop.Mathematicalmodelingwasusedtosimulatedivingtofirstbasesuchthattheslidewouldbeginwhenthehandtouchesthebase.Results:Baseduponoverallresults,thequickestwaytothebaseisbyrunningthroughit,followedbyhead-first,feet-first,andrunningtoastop.Conclusion:Therewasanon-significanttrendtowardanadvantagefordivingintofirstbaseoverrunningthroughit,butmoreresearchisneeded,andeveniftheadvantageisreal,therisksofexecutingthistechniqueprobablyoutweightheminisculegain.

简介：Modernizationandmaintenanceofadamoftenrequireemptyingthereservoir,aprocessthatcancausemudbankinstabilitiesandenvironmentaldisturbances.Inordertoaddresstheproblemofmudbankcollapsecharacterization,astudyisconductedinpartnershipwiththeLaboratoireNationald'Hydraulique(LNH),asubsidiaryofElectricitédeFrance(EDF).Thispaperpresentsageotechnicalmodelingofsubmergedandemergentmudbankstabilityandacomparisonofthemodelresultswiththemeasurementscarriedoutthroughoutthewholereservoir.

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简介：Seismicsafetyassessmentofgravitydamshasbecomeamajorconcerninmanyregionsoftheworldwhiletheeffectsofverticalseismicaccelerationsontheresponseofstructuresremainpoorlyunderstood.Thispaperfirstinvestigatestheeffectofincludingverticalaccelerationsintheslidingresponseanalysisofgravitydamssubjectedtoarangeofhistoricalgroundmotionrecordsseparatedintwogroupsaccordingtotheirsource-to-sitedistance.Analysesshowedthattheincidenceofverticalaccelerationsontheslidingresponseofgravitydamsissignificantlyhigherfornear-sourcerecordsthanforfarsourcerecords.Thepseudo-static30%loadcombinationrule,commonlyusedinpracticetoaccountforthenon-simultaneousoccurrenceofthepeakhorizontalandverticalaccelerations,yieldedgoodapproximationsoftheminimumsafetyfactorsagainstslidingcomputedfromtime-historyanalyses.Amethodforempiricallyestimatingtheverticalresponsespectrabasedonhorizontalspectra,accountingforthedifferenceinfrequencycontentandamplitudesbetweenthetwocomponentsisinvestigated.Resultsfromanalysesusingspectrumcompatiblehorizontalandverticalsyntheticrecordsalsoapproximatedwelltheslidingresponseofagravitydamsubjectedtoseriesofsimultaneoushorizontalandverticalhistoricalearthquakerecords.

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简介：Thestudyoffrictionalpropertiesofhumanskinisimportantformedicalresearch,skincareproductsandtextileexploi-tation.Inordertoinvestigatetheinfluenceofnormalloadandslidingspeedonthefrictionalpropertiesofskinanditspossiblemechanism,testswerecarriedoutonamulti-specimenfrictiontester.Whenthenormalloadincreasesfrom0.1Nto0.9N,normaldisplacementandthefrictioncoefficientofskinincrease.Thefrictioncoefficientisdependentontheload,indicatingthatbothadhesionanddeformationcontributetothefrictionbehaviour.Thedeformationfrictionwasinterpretedusingtheploughmodeloffriction.Whenslidingspeedincreasesfrom0.5mm·s?1to4mm·s?1,thefrictioncoefficientincreasesand'stick-slip'phenomenaincrease,indicatingthathystereticfrictioncontributestothefriction.Thehystereticfrictionwasin-terpretedusingschematicofenergytranslationduringtherigidsphericalprobeslidingonthesoftskinsurface,whichprovidesanexplanationfortheinfluenceoftheslidingspeedonthefrictionalcharacteristicsoftheskin.

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简介：这份报纸建议为不明确的系统滑动模式(HOSM)控制器的一份适应不可分的更高的订单。而不是常规控制输入，控制输入的衍生物在建议控制法律被使用。在控制器的不连续的符号函数被做对控制输入的时间衍生物起作用。集成衍生物控制信号获得的实际控制信号光滑、啁啾免费。在建议控制器使用的适应调节法律消除系统无常的上面的界限的优先的知识的需要。建议控制器的稳定性和坚韧性被使用古典Lyapunov标准证明。模拟结果表明建议控制计划的优点。

简介：滑动模式控制的适应backstepping与输入浸透为不明确的非线性的系统的一个班被建议。一个命令过滤了途径被用来阻止输入浸透破坏神经网络(NN)的适应能力。控制法律和NN的适应更新法律在Lyapunov功能的意义被导出，因此稳定性能甚至在输入浸透下面被保证。建议控制法律对骚乱是柔韧的，并且它能也消除输入浸透的影响。模拟结果显示建议控制器有好表演。

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简介：Ithaslongbeenrecognizedthattherotationofsingleparticlesplaysaveryimportantroleinsimulationsofgranularflowusingthediscreteelementmethod(DEM).ManyresearchershavealsopointedoutthattheeffectofrollingresistanceatthecontactpointsshouldbetakenintoaccountinDEMsimulations.However,evenforthesimplestcaseinvolvingtwo-dimensionalcircularparticles,thereisnoagreementonthebestwaytodefinerollingandsliding,anddifferentdefinitionsandcalculationsofrollingandslidinghavebeenproposed.Ithasevenbeensuggestedthatauniquerollingandslidingdefinitionisnotpossible.Inthispaperweassessresultsfrompreviousstudiesonrollingandslidingindiscreteelementmodelsandfindthatsomeresearchershaveoverlookedtheeffectofparticlesofdifferentsizes.Afterconsideringtheparticleradiusinthederivationofrollingvelocity,allresultsreachthesameoutcome:auniquesolution.Wealsopresentaclearandsimplederivationandvalidateourresultusingcasesofrolling.Suchadecompositionofrelativemotionisobjective,orindependentofthereferenceframeinwhichtherelativemotionismeasured.

简介：WeproposeaBPNNbasedadaptiveslidingmodecontrolschemeforspeedtrackingofaDCmotorwithunknownsystemnonlinearities.Theinput-outputlinearizationtechniqueisusedtocancelthenonlinearities,andoutputoftheBPNNisincorporatedintothecontrollerintheproposedscheme.ItisshownthattherotorspeedofaDCmotorcanfollowanyarbitrarilyselectedtrajectoriesundervariableloadtorque.Thentheapplicationoftheapproachistestedviacomesimulations.

简介：Theproblemofrobustifyinglinearquadraticregulators(LQRs)foraclassofuncertainaffinenonlinearsystemsisconsidered.First,theexactlinearizationtechniqueisusedtotransformanuncertainnonlinearsystemintoalinearoneandanoptimalLQRisdesignedforthecorrespondingnominalsystem.Then,basedontheintegralslidingmode,adesignapproachtorobustifyingtheoptimalregulatorisstudied.Asaresult,thesystemexhibitsglobalrobustnesstouncertaintiesandtheidealslidingmodedynamicsisthesameasthatoftheoptimalLQRforthenominalsystem.Aglobalrobustoptimalslidingmodecontrol(GROSMC)isrealized.Finally,anumericalsimulationisdemonstratedtoshowtheeffectivenessandsuperiorityoftheproposedalgorithmcomparedwiththeconventionaloptimalLQR.

简介：Theexperimentalstudyofthechangeofwavevelocityinfaultregionsbeforeinstabilityoffrictionalslidingofrockswasconducted.Experimentsshowthatbeforetheinstabilityoffrictionalslidingofrocks,thechangeofwavevelocitycannotbeobservedalonglinesononesideofthefault,buttheprecursorofthedecreaseofwavevelocitycanbeobservedalonglinesacrossthefault.Therefore,whenwetrytopredicttheearthquakesofthestick-sliptypeinfaultregionsbyusingtheanomalyofwavevelocity,themeasuringlinesacrossthefaultsshouldbeselected.

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简介：AccordingtoaclassofnonlinearSISOdiscretesystems,thefuzzyslidingmodecontrolproblemisconsidered.BasedonTakagi-Sugenofuzzymodelmethod,afuzzymodelisdesignedtodescribethelocaldynamicperformanceofthegivennonlinearsystems.Byusingtheslidingmodecontrolapproach,theglobalcontrollerisconstructedbyintegratingallthelocalstatecontrollersandtheglobalsupervisoryslidingmodecontroller.Thetrackingproblemcanbeeasilydealtwithbytakingadvantageofthecombinedcontroller,andtherobustnessperformanceisimprovedfinally.Asimulationexampleisgiventoshowtheeffectivenessandfeasibilityofthemethodproposed.

简介：Thisletterpresentsananalyticalsolutiontothehydrodynamiclubricationofacircularpointcontactslidingoveraflatsurfacewithcavitation.ThesolutionisfoundbysolvingtheReynoldsequationwithReynoldsboundaryconditionforcavitation.Thecavitationboundaryisshowntobestraightlinesdirected108.4°againsttheslidingdirection.Theresultisexperimentallyverifiedinthelimitoflargevaluesofviscosity,slidingvelocityandradiusofasphericalball.Thesolutionraisesquestionsaboutthecouplingbetweencavitationandfilmruptureandcanbeusedasanindependentcheckonthevalidityofnumericalsolutions.

简介：Anadaptivefuzzyslidingmodecontrol(AFSMC)approachisproposedforaroboticairship.First,themathematicalmodelofanairshipisderivedintheformofanonlinearcontrolsystem.Second,anAFSMCapproachisproposedtodesigntheattitudecontrolsystemofairship,andtheglobalstabilityoftheclosed-loopsystemisprovedbyusingtheLyapunovstabilitytheorem.Finally,simulationresultsverifytheeffectivenessandrobustnessoftheproposedcontrolapproachinthepresenceofmodeluncertaintiesandexternaldisturbances.

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简介：Anoptimalactiveslidingmodecontrollerwithspecifieddecayratedesignisproposedtocontrolthewave-inducedoffshorejacket-typeplatformwithactivemassdamper(AMD).IrregularwaveloadingisapproximatedbyfinitesumsofFourierseries,anditsdynamiccharacteristicsaregovernedbyanexosystemderivedfromthelinearizedMorisonequation.Theoffshoreplatformsystemisfirstdecomposedintotwovirtualsubsystemsbasedonalineartransformation.ByconsideringthevelocityofAMDasavirtualcontrolforceforthefirstsubsystem,theoptimalvirtualcontrollerisderived.Furthermore,anoptimalslidingmodesurfacewithspecifieddecayrateisproposed.Then,theactiveslidingmodecontrollerisdesignedtoensurethatthestatetrajectoriesreachtheslidingsurfaceinfinitetimeandremainonitthereafter.Numericalsimulationisemployedtoverifytheeffectivenessoftheproposedapproach.