简介：Theeffectsoftwogeometricrefinementstrategieswidespreadinnaturalstructures,chiralityandself-similarhierarchy,onthein-planeelasticresponseoftwo-dimensionalhoneycombswerestudiedsystematically.Simpleclosed-formexpressionswerederivedfortheelasticmoduliofseveralchiral,antichiral,andhierarchicalhoneycombswithhexagonandsquarebasednetworks.Finiteelementanalysiswasemployedtovalidatetheanalyticalestimatesoftheelasticmoduli.Theresultswerealsocomparedwiththenumericalandexperimentaldataavailableintheliterature.WefoundthatintroducingahierarchicalrefinementincreasestheYoung'smodulusofhexagonbasedhoneycombswhiledecreasestheirshearmodulus.Forsquarebasedhoneycombs,hierarchyincreasestheshearmoduluswhiledecreasingtheirYoung'smodulus.IntroducingchiralitywasshowntoalwaysdecreasetheYoung'smodulusandPoisson'sratioofthestructure.However,chiralityremainstheonlyroutetoauxeticity.Inparticular,wefoundthatanti-tetra-chiralstructureswerecapableofsimultaneouslyexhibitinganisotropy,auxeticity,andremarkablylowshearmodulusasthemagnitudeofthechiralityoftheunitcellincreases.

简介：NanofluidswerepreparedbydispersingCunanoparticles(~20nm)inn-tetradecanebyatwo-stepmethod.Theeffectivethermalconductivitywasmeasuredforvariousnanoparticlevolumefractions(0.0001-0.02)andtemperatures(306.22-452.66K).TheexperimentaldatacompareswellwiththeJangandChoimodel.Thethermalconductivityenhancementwaslowerabove391.06Kthanforthatbetween306.22and360.77K.Theinterfacialthermalresistanceincreasedwithincreasingtemperature.Theeffectivethermalconductivityenhancementwasgreaterthanthatobtainedwithamoreviscousfluidasthebasemediaat452.66KbecauseofnanoconvectioninducedbynanoparticleBrownianmotionathightemperature.

简介：Thesubsystemsynthesismethodhasbeendevelopedinordertoimprovecomputationalefficiencyforamultibodyvehicledynamicsmodel.Usingthesubsystemsynthesismethod,equationsofmotionofthebasebodyandeachsubsystemcanbesolvedseparately.Inthesubsystemsynthesismethod,variouscoordinatesystemscanbeusedandvariousintegrationmethodscanbeappliedineachsubsystem,aslongastheeffectivemassmatrixandtheeffectiveforcevectorareproperlyproduced.Inthispaper,comparativestudyhasbeencarriedoutforthesubsystemsynthesismethodwithCartesiancoordinatesandwithjointrelativecoordinates.Twodifferentintegrationmethodssuchasanexplicitintegratorandanexplicitimplicitintegratorareemployed.Inordertoseetheaccuracyandcomputationalefficiencyfromthedifferentmodelsbasedonthedifferentcoordinatesystemsanddifferentintegrationmethods,aroughterrainrunsimulationshasbeencarriedoutwitha6×6off-roadmultibodyvehiclemodel.

简介：Theblended-fuelbasededdy-dissipation-conceptcombustionmodelwasnewlydevelopedintheFireFOAMframework,andappliedtosimulate30cm×30cmheptane-ethanolpoolfire.Comparisonwasmadeoffireheight,centerlinetemperatureagainstexperimentalmeasurements,whichshowsthattheymatchverywellwitheachother.However,furtherstudiesareneededtoexaminethevalidationofthismodelinfiresimulationswithvariousscales.

简介：这份报纸成功地为nanobeams在非局部的有弹性的压力地理论处理了三个关键却俯看的问题：增加非局部的效果的存在导致的(i)在许多减少了nanostructural僵硬，然而并非一致地为所有，学习的盒子，即，增加的静态的偏转，减少的自然频率和减少的弄弯的负担，吗尽管根据非局部的弹性地，理论首先由Eringen建立了的物理直觉不那样告诉？(ii)nanoscale完成的吸引人的结论在在学习的许多作为模范的盒子中的答案是失踪的，例如，把有在它的尖端的点负担的伸臂nanobeam的偏转弄弯；并且(iii)另外的高顺序的边界的不存在为一个高顺序的管理调节微分方程。在nanomechanics和一条准确变化主要途径使用非局部的弹性领域理论，我们为nanobeams弯曲导出新平衡条件，管理微分方程的领域和边界条件。这些方程和条件包含在符号关于相反的必要高顺序的微分条款以前在非局部的nano结构的静电干扰和动力学学习。在高顺序的条款的差别关于这份报纸的结论导致nanoscale效果的反向的趋势。有效地，这份报纸报导新平衡条件，管理为nanobeams弯曲的微分方程和边界条件和真基本静态的回答。非局部的nanostructures的广泛地接受的平衡条件事实上不在平衡，这也被结束，但是他们能被使完美非局部的弯曲时刻应该到一有效非局部的弯曲时刻被代替。这些结论被证实，在一般意义，由在象种类坡度理论，修改夫妇压力模型和实验那样的nanostructural模型的另外的途径。关键词弯曲-有效非局部的弯曲时刻-nanobeam-nanomechanics-nanoscale-非局部的有弹性的应力-种类坡度汉语Librarary分类O3432000数学题目分类74A60由郭工程从香港特别行政区的研究资助委员会由资助支持了的我x交流了(没有。CityU117406）

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简介：在现在的工作，一个计算框架为多尺度的建模和稳固的燃料的分析被建立。一个收拾行李的算法，作为范围或磁盘认为铵高氯酸盐(AP)和铝(艾尔)是粒子被开发匹配尺寸分发和稳固的燃料的卷部分。一个homogenization理论被采用计算一个代表性的体积元素(RVE)的吝啬的压力和紧张。用吝啬的结果，RVE的一种合适的尺寸被决定。没有考虑在粒子和矩阵之间的接口，燃料的松驰的几数字模拟被执行。松驰效果和依赖于应用负担的燃料的非线性的机械行为被讨论。新技术说出基于表面的连贯的行为的A被建议描述由二成分组成的粒子dewetting的现象：一个损坏开始标准和一条损坏进化法律。就接触损坏行为而言的几个例子被计算，损坏接口引起的也非线性的行为在这份报纸被讨论。而且，损坏接口上的批评接触压力，起始的接触僵硬和接触失败距离的效果当模特儿被学习了。

简介：Apolymericgelisanaggregateofpolymersandsolventmolecules,whichcanretainitsshapeafteralargedeformation.ThedeformationbehaviorofpolymericgelswasoftendescribedbasedontheFlory-Rehnerfreeenergyfunctionwithoutconsideringtheinfluenceofchainentanglementsonthemechanicalbehaviorofgels.Inthispaper,anewhybridfreeenergyfunctionforgelsisformulatedbycombiningtheEdwards-Vilgisslip-linkmodelandtheFlory-Hugginsmixingmodeltoquantifythetime-dependentconcurrentprocessoflargedeformationandmasstransport.Thefiniteelementmethodisdevelopedtoanalyzeexamplesofswelling-induceddeformation.Simulationresultsarecomparedwithavailableexperimentaldataandshowgoodagreement.Theinfluenceofentanglementsonthetime-dependentdeformationbehaviorofgelsisalsodemonstrated.Thestudyoflargedeformationkineticsofpolymericgelisusefulfordiverseapplications.

简介：Anumericalmethod,theso-calledmultiplemonopole(MMoP)method,basedonthegeneralizedmultipoletechnique(GMT)isproposedtocalculatethebandstructuresofin-planewavesintwo-dimensionalphononiccrystals,whicharecomposedofarbitrarilyshapedcylindersembeddedinasolidhostmedium.Tofindtheeigenvalues(eigenfrequencies)oftheproblem,besidesthesourcesusedtoexpandthewavefields,anextramonopolesourceisintroducedwhichactsastheexternalexcitation.Byvaryingtheexcitationfrequency,theeigenvaluescanbelocalizedastheextremepointsofanappropriatelychosenfunction.BysweepingthefrequencyrangeofinterestandtheboundaryoftheirreduciblefirstBrillouinzone(FBZ),thebandstructurescanbeobtained.Sometypicalnumericalexampleswithdifferentacousticimpedanceratiosandwithinclusionsofvariousshapesarepresentedtovalidatetheproposedmethod.

简介：Althoughthestructuredlightsystemthatusesdigitalfringeprojectionhasbeenwidelyimplementedinthree-dimensionalsurfaceprofilemeasurement,themeasurementsystemissusceptibletonon-linearerror.Inthiswork,weproposeaconvenientlook-up-table-based(LUT-based)methodtocompensateforthenon-linearerrorincapturedfringepatterns.Withoutextracalibration,thisLUT-basedmethodcompletelyutilizesthecapturedfringepatternbyrecordingthefull-fielddifferences.Then,aphasecompensationmapisestablishedtorevisethemeasuredphase.Experimentalresultsdemonstratethatthismethodworkseffectively.

简介：Inthispaper,thenonlinearconjugatemapbasedontheconjugateRackwitz-FiesslerandHasofer-Lind(CHL-RF)methodisusedtoevaluatethereliabilityusingfirstorderreliabilitymethodoftheembeddednanocompositebeam,whichismadefrompolymerreinforcedwithcarbonnanotubs(CNTs).ThestructureissimulatedwithTimoshenkobeammodel.TheMori-Tanakamethodisappliedforobtainingtheeffectivepropertiesofnanocompositebeam.Thesurroundingelasticmediumisconsideredbyspringandshearconstants.UtilisingenergymethodandHamilton'sprincipal,thegoverningequationsareobtained.Usingananalyticalmethod,thebucklingperformancefunctionofstructureisobtained.Theinfluencesofthebasicrandomvariablesincludingthelengthtothicknessratioofbeam(L/h),springconstantandshearconstantoffoundationwithrespecttothevolumefractionofCNTsareinvestigatedonthereliabilityindexofthenanocompositebeamsubjectedtoaxialforceof20GPa.Theresultsindicatedthatthefailureprobabilitiesofthestudiedthenanocompositebeamarethesensitivetothelengthtothicknessofbeam(L/h)andspringconstantoffoundationvariables.

简介：Inthispaper,thenonlinearconjugatemapbasedontheconjugateRackwitz-FiesslerandHasofer-Lind(CHL-RF)methodisusedtoevaluatethereliabilityusingfirstorderreliabilitymethodoftheembeddednanocompositebeam,whichismadefrompolymerreinforcedwithcarbonnanotubs(CNTs).ThestructureissimulatedwithTimoshenkobeammodel.TheMori-Tanakamethodisappliedforobtainingtheeffectivepropertiesofnanocompositebeam.Thesurroundingelasticmediumisconsideredbyspringandshearconstants.UtilisingenergymethodandHamilton'sprincipal,thegoverningequationsareobtained.Usingananalyticalmethod,thebucklingperformancefunctionofstructureisobtained.Theinfluencesofthebasicrandomvariablesincludingthelengthtothicknessratioofbeam(L/h),springconstantandshearconstantoffoundationwithrespecttothevolumefractionofCNTsareinvestigatedonthereliabilityindexofthenanocompositebeamsubjectedtoaxialforceof20GPa.Theresultsindicatedthatthefailureprobabilitiesofthestudiedthenanocompositebeamarethesensitivetothelengthtothicknessofbeam(L/h)andspringconstantoffoundationvariables.

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简介：Uncertaintyisinherentandunavoidableinalmostallengineeringsystems.Itisofessentialsignificancetodealwithuncertaintiesbymeansofreliabilityapproachandtoachieveareasonablebalancebetweenreliabilityagainstuncertaintiesandsystemperformanceinthecontroldesignofuncertainsystems.Nevertheless,reliabilitymethodswhichcanbeuseddirectlyforanalysisandsynthesisofactivecontrolofstructuresinthepresenceofuncertaintiesremaintobedeveloped,especiallyinnon-probabilisticuncertaintysituations.Inthepresentpaper,theissueofvibrationcontrolofuncertainstructuresusinglinearquadraticregulator(LQR)approachisstudiedfromtheviewpointofreliability.Ane?cientnon-probabilisticrobustreliabilitymethodforLQR-basedstaticoutputfeedbackrobustcontrolofuncertainstructuresispresentedbytreatingboundeduncertainparametersasintervalvariables.Theoptimalvibrationcontrollerdesignforuncertainstructuresiscarriedoutbysolvingarobustreliability-basedoptimizationproblemwiththeobjectivetominimizethequadraticperformanceindex.Thecontrollerobtainedmaypossessoptimumperformanceundertheconditionthatthecontrolledstructureisrobustlyreliablewithrespecttoadmissibleuncertainties.Theproposedmethodprovidesanessentialbasisforachievingabalancebetweenrobustnessandperformanceincontrollerdesignofuncertainstructures.Thepresentedformulationsareintheframeworkoflinearmatrixinequalityandcanbecarriedoutconveniently.Twonumericalexamplesareprovidedtoillustratethee?ectivenessandfeasibilityofthepresentmethod.

简介：Concerningthespecificdemandonsolvingthelong-termconjugateheattransfer(CHT)problem,anewalgorithmoftheglobaltightly-coupledtransientheattransferbasedonthequasi-steadyflowfieldisfurtherputforward.Comparedtothetraditionalloosely-coupledalgorithm,thecomputationalefficiencyisfurtherimprovedwiththegreatlyreducedupdatefrequencyoftheflowfield,andmoreovertheupdatestepoftheflowfieldcanbereasonablydeterminedbyusingtheengineeringempiricalformulaoftheNusseltnumberbasedonthechangesoftheinletandoutletboundaryconditions.Takingaductheatedbyinnerforcedairflowheatingprocessasanexample,thecomparingresultstothetightly-coupledtransientcalculationbyFluentsoftwareshowsthatthenewalgorithmcansignificantlyimprovethecomputationalefficiencywithareasonableaccuracyonthetransienttemperaturedistribution,suchasthecomputingtimeisreducedto22.8%and40%whiletheductwalltemperaturedeviationare7%and5%respectivelyusingtwoflowupdatetimestepof100sand50sonthevariableinlet-flowrateconditions.

简介：pearlitic钢与随机的取向由众多的pearlitic殖民地组成，并且每个殖民地由铁酸盐和渗碳体的许多平行薄片组成。这种材料的组成的行为可以包含两固有的anisotropy，塑料变丑导致anisotropy。对为这种双阶段的材料的周期的粘性的描述被一个基于微观结构的组成的模型的使用为一个pearlitic殖民地，和山为椭圆体的包括合并各向异性的Eshelby张肌的前後一致的计划建议。相应数字算法被开发。pearlitic钢BS11和单相的冷抽的铜的回答使遭到了到一相称性地周期的装载被分析。分析结果与试验性的同意很好。与用各向同性的Eshelby张肌的结果相比，各向同性的近似能以一个简单得多的方法提供可接受的全面回答，这被显示出。