简介：Animprovedconstrained(IC)steeringlawforsinglegimbalcontrolmomentgyros(SGCMGs)withdeformedpyramidconfiguration(DPC)isproposed.Firstofall,theoriginalsystemwithfivepyramidconfiguration(FPC)whosetwoadjacentgyrosareinfailurestateisreconfiguredasadegradedsystemwithDPC.Then,thesingularangularmomentumhypersurfacesoftheoriginalandthedegradedsystemsareplottedviathesingularangularmomentumequationofSGCMGs.Basedonsingularsurfaces,thedifferencesbetweenFPCandDPCinsingularityandmomentumenvelopeareobtaineddirectly,whichprovideanimportantreferenceforsteeringlawdesignofDPC.Finally,anICsteeringlawisdesignedandappliedtoDPC.ThesimulationresultsdemonstratethattheICsteeringlawhasadvantagesinsimplicityofcalculation,avoidanceofsingularityandexactnessofoutputtorque,whichendowthedegradedsystemwithfinecontrollabilityinarestrictedworkspace.

简介：Animprovedpreciseintegrationmethod(IPIM)forsolvingthedifferentialRiccatiequation(DRE)ispresented.ThesolutiontotheDREisconnectedwiththeexponentialofaHamiltonianmatrix,andthepreciseintegrationmethod(PIM)forsolvingtheDREisconnectedwiththescalingandsquaringmethodforcomputingtheexponentialofamatrix.TheerroranalysisofthescalingandsquaringmethodfortheexponentialofamatrixisappliedtothePIMoftheDRE.Basedontheerroranalysis,thecriterionforchoosingtwoparametersofthePIMisgiven.ThreekindsofIPIMsforsolvingtheDREareproposed.ThenumericalexamplesshowthattheIPIMisstableandgivesthemachineaccuracysolutions.

简介：Anorganicsilaneacrylateresin（PMBK）wassynthesizedbyfree-radicalsolutionpolymerizationusingmethylmethacrylate,butylacrylateand（3-methacryloxypropyl）trimethoxysilaneasmonomers.Aluminum（Al）particleswerethenencapsulatedininorganic-organichybridfilmsthatwerepreparedbyhydrolysisandcondensationofPMBKandtetraethylorthosilicate（TEOS）onthesurfaceofAlpigments.CharacterizationresultsshowedthatPMBKandTEOScouldsimultaneouslyhydrolyzeandcondensewithhydroxylgroupsonthesurfaceoftheAlparticlestoformcompositeAlparticlescoatedwithinorganic-organichybridfilms.ComparedwithrawAlparticles,thecorrosionresistanceandadhesivepropertiesofpaintfilmscontainingthecompositeAlparticleswereimprovedgreatly,whiletheglossinessofthepaintfilmsdecreasedslightly,from48.6°to47.0°.Inalkalinemedia（pH11）,thevolumeofevolvedH2ofcompositeAlparticleswasonly3.5mL,whereasthatofrawAlwas83.5mL.TheglossinessofpaintfilmscontainingcompositeAlparticlesdecreasedby1.66%afterimmersioninalkalinemediafor24h,whereasthatofrawAldecreasedby14.82%.Peel-offtestsofthepaintfilmsshowedthatthecompositeparticlesmovedslightlyawayfromthepaintfilms.Incontrast,therawAlparticleswereseriouslydesquamated,suggestingencapsulationofhybridfilmscangreatlyimprovetheadhesivepropertiesofAlparticlesinpaintfilms.

简介：Monoclinicparacetamol(PA)isnotoriousasapoorlycompactiblemodeldrug.Polyvinylpyrrolidone(PVP)isapolymerthatcanactasaneffectivebindertoimprovethemechanicalpropertiesofPA.ItissurprisinghoweverthattheroleofmixingconditionsonthephysicochemicalandmechanicalpropertiesofPA-PVPmixtureshasnotbeenreportedpreviously.TheresultsofthisworkshowedthatPA-PVPmixturescontaining5%(w/w)PVPpreparedusinghighenergymixingconditionshadconsiderablysmallerparticlesizedistributionsandhighercohesivitiesthanmixturespreparedusinglowenergymixingconditions.Solid-stateanalysisdidnotdetectanychangeinthemonocliniccrystallineformofPAaftermixingwithPVP.ThefollowingrankorderoftabletabilityforPA-PVPmixtureswasobtainedaccordingtothemixingcondition:lowshear-mediumshear

简介：纸论述改进没有元素的Galerkin(IEFG)为三维的波浪繁殖的方法。改进移动最少平方(IMLS)近似被采用构造形状函数，它与一个重量函数把一个直角的函数系统用作基础函数。与常规移动相比最少平方(MLS)近似，在IMLS的代数学的方程系统近似不是性恶的，并且没有导出反的矩阵，能直接被解决。因为比在MLS近似在IMLS有更少系数，更少节点比在没有元素的Galerkin方法在IEFG方法被选择。因此，IEFG方法有更高的计算速度。在IEFG方法，Galerkin弱形式被采用获得一个discretized系统方程，并且惩罚方法被使用强加必要边界条件。为二点的边界价值问题的传统的差别方法为时间discretization被选择。当波浪方程和边界起始的条件取决于时间，可伸缩的参数，节点的数字和时间，步长度为集中学习被考虑。

简介：Animprovedsmoke-wireflowvisualizationtechniqueusingalargecapacitorasthepowersourcewasproposed.Electriccurrentdischargedfromcapacitorswasusedtoheatafinemetalwiresuspendedintheflowfield.Theoildropletsattachedtothewirewerevaporizedandsmokefilamentsfollowedtheflowmotions.Adigitalcamerawasusedtorecordtheimagesofthesmokefilaments.Theactionsofdischargingandcamerashutterweretriggeredbysignalsfromamicrocontrollertoensuretheaccuratetiming.Clearimagesofthestreaklineswerecapturedatafreestreamvelocityupto12.9m/s,muchhigherthanthelimitsoftheexistingtechniques.

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简介：LatticeBoltzmannmethodisoneofthewidelyusedinmultiphasefluidflow.However,thetwomaindisadvantagesofthismethodaretheinstabilityofnumericalcalculationsduetothelargedensityratiooftwophasesandimpossibilityofthetemperaturedistributiontobefedbackintothevelocitydistributionfunctionwhenthetemperatureissimulated.BasedonthecombinationprescribedbyInamuro,thelargedensityratiotwo-phaseflowmodelandthermalmodelmakesthedensityratioofthemodelsimulationtobeincreasedto2778:1byoptimizingtheinterfacedistributionfunctionoftwo-phasewhichimprovestheaccuracyofdifferentialformat.Thephasetransitiontermisaddedassourcetermintothedistributionfunctioncontrollingtwophaseorderparameterstodescribethetemperatureeffectonthegas-liquidphasetransition.Thelatentheatgeneratedfromthephasechangeisalsoaddedasasourcetermintothetemperaturedistributionfunctionwhichsimulatesthemovementoftheflowunderthecommoncouplingofdensity,velocity,pressureandtemperature.Thedensityandthetemperaturedistributionofsinglebubblearesimulated.Comparisonofthesimulationresultswithexperimentalresultsindicatesagoodagreementpointingouttheeffectivenessoftheimprovedmodel.

简介：Inthispaper,thespectralelementmethod(SEM)isimprovedtosolvethemovingloadproblem.Inthismethod,astructurewithuniformgeometryandmaterialpropertiesisconsideredasaspectralelement,whichmeansthattheelementnumberandthedegreeoffreedomcanbereducedsignificantly.BasedonthevariationalmethodandtheLaplacetransformtheory,thespectralstiffnessmatrixandtheequivalentnodalforceofthebeam-columnelementareestablished.ThestaticGreenfunctionisemployedtodeducetheimprovedfunction.Theproposedmethodisappliedtotwotypicalengineeringpractices—theone-spanbridgeandthehorizontaljibofthetowercrane.Theresultshaverevealedthefollowing.First,thenewmethodcanyieldextremelyhigh-precisionresultsofthedynamicdeflection,thebendingmomentandtheshearforceinthemovingloadproblem.Inmostcases,therelativeerrorsaresmallerthan1%.Second,bycomparingwiththefiniteelementmethod,onecanobtainthehighlyaccurateresultsusingtheimprovedSEMwithsmallerelementnumbers.Moreover,themethodcanbewidelyusedforstaticallydeterminateaswellasstaticallyindeterminatestructures.Third,thedynamicdeflectionofthetwin-liftjibdecreaseswiththeincreaseinthemovingloadspeed,whereasthecurvatureofthedeflectionincreases.Finally,thedynamicdeflection,thebendingmomentandtheshearforceofthejibwillallincreaseasthemagnitudeofthemovingloadincreases.

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简介：Thelargedesignfreedomofvariable-stiffness(VS)compositematerialpresupposesitspotentialforwideengineeringapplication.PreviousresearchindicatesthatthedesignofVScylindricalstructureshelpstoincreasethebucklingloadascomparedtoquasi-isotropic(QI)cylindricalstructures.Thispaperfocusesontheanti-bucklingperformanceofVScylindricalstructuresundercombinedloadsandtheefficientoptimizationdesignmethod.Twokindsofconditions,bendingmomentandinternalpressure,andbendingmomentandtorqueareconsidered.Influencesofthegeometricaldefects,ovality,onthecylinder'sperformancesarealsoinvestigated.Toincreasethecomputationalefficiency,anadaptiveKrigingmeta-modelisproposedtoapproximatethestructuralresponseofthecylinders.InthisimprovedKrigingmodel,amixedupdatingruleisusedinconstructingthemeta-model.Ageneticalgorithm(GA)isimplementedintheoptimizationdesign.TheoptimalresultsshowthatthebucklingloadofVScylindersinallcasesisgreatlyincreasedascomparedwithaQIcylinder.

简介：Dynamicfluid-solidinteractionsarewidelyfoundinchemicalengineering,suchasinparticle-ladenflows,whichusuallycontaincomplexmovingboundaries.Theimmersedboundarymethod(IBM)isaconvenientapproachtohandlefluid-solidinteractionswithcomplexgeometries.Inthiswork,Uhlmann’sdirect-forcingIBMisimprovedandimplementedonasupercomputerwithCPU-GPUhybridarchitecture.Thedirect-forcingIBMismodifiedasfollows:thePoisson’sequationforpressureissolvedbeforeevaluationofthebodyforce,andtheforceisonlydistributedtotheCartesiangridsinsidetheimmersedboundary.Amultidirectforcingschemeisusedtoevaluatethebodyforce.Thesemodificationsresultinadivergence-freeflowfieldinthefluiddomainandtheno-slipboundaryconditionattheimmersedboundarysimultaneously.Thismethodisimplementedinanexplicitfinite-differencefractional-stepscheme,andvalidatedby2Dsimulationsoflid-drivencavityflow,Couetteflowbetweentwoconcentriccylindersandflowoveracircularcylinder.Finally,themethodisusedtosimulatethesedimentationoftwocircularparticlesinachannel.Theresultsagreeverywellwithpreviousexperimentalandnumericaldata,andaremoreaccuratethantheconventionaldirect-forcingmethod,especiallyinthevicinityofamovingboundary.

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简介：Fastsolvinglarge-scalelinearequationsinthefiniteelementanalysisisaclassicalsubjectincomputationalmechanics.Itisakeytechniqueincomputeraidedengineering(CAE)andcomputeraidedmanufacturing(CAM).Thispaperpresentsahigh-efciencyimprovedsymmetricsuccessiveover-relaxation(ISSOR)preconditionedconjugategradient(PCG)method,whichmaintainstheconvergenceandinherentparallelismconsistentwiththeoriginalform.Ideally,thecomputationcanbereducednearlyby50%ascomparedwiththeoriginalalgorithm.Itissuitableforhigh-performancecomputingwithitsinherentbasichigh-efciencyoperations.Bycomparingwiththenumericalresults,itisshownthattheproposedmethodhasthebestperformance.